%0 Journal Article %J Nanomaterials %D 2023 %T Anomalous optical properties of KTN:Li ferroelectric super crystals %A L. Falsi %A S. Macis %A Y. Gelkop %A L. Tartara %A E. P. Di Pietro %A A. Perucchi %A Garcia, Y. %A Perepelitsa, G. %A DelRe, E. %A Agranat, A.J. %A S. Lupi %B Nanomaterials %V 13 %G eng %N 899 %0 Journal Article %J Bioengineering and Biotechnology %D 2022 %T Enhancing DNT detection by a bacterial bioreporter: directed evolution of the transcriptional activator YhaJ %A T. Elad %A B. Shemer %A S. Simanowitz %A Kabessa, Y. %A Y. Mizrachi %A E. Shpigel %A Agranat, A.J. %A S. Belkin %B Bioengineering and Biotechnology %V 10 %G eng %N 821835 %0 Journal Article %J Phys. Rev B %D 2022 %T Key role of polar nanoregions in the cubic-to-tetragonal phase transition of potassium-based perovskites %A Parravicini, J. %A DelRe, E. %A S. Perego %A M. Acciarri %A S. Binetti %A Garcia, Y. %A G. Parapelitsa %A Agranat, A.J. %A G. Parravicini %B Phys. Rev B %V 106 %G eng %N 064107 %0 Journal Article %J Physical Review Letters %D 2022 %T Intense wave formation from multiple soliton fusion and the role of extra dimensions %A F. Xin %A L. Falsi %A D. Pierangeli %A F. Fusella %A Perepelitsa, G. %A Garcia, Y. %A Agranat, A.J. %A DelRe, E. %B Physical Review Letters %V 129 %G eng %N 043901 %0 Journal Article %J Biosensors and Bio-Electronics %D 2021 %T An autonomous bioluminescent bacterial biosensor module for outdoor sensor networks, and its application for the detection of buried explosives %A Agranat, A.J. %A Kabessa, Y. %A Shemer B. %A Shpigel E. %A Schwartsglass, O. %A Atamneh L. %A Uziel Y. %A Mizrachi Y. %A Eizenberg M. %A Garcia, Y. %A Perepelitsa, G. %A Belkin S. %B Biosensors and Bio-Electronics %V 185 %G eng %N 113253 %0 Journal Article %J Optics Letters %D 2021 %T Electro optic active Q switched Tm:YLF laser based on polarization modulation %A Noach S. %A Nahear R. %A Vidal Y. %A Garcia, Y. %A Agranat, A.J. %B Optics Letters %V 46 %P 1971-1974 %G eng %N 8 %0 Journal Article %J Phys. Rev. Letters %D 2021 %T Evidence of chaotic dynamics in three-soliton collisions %A Xin F. %A Di Mei, F. %A Falsi L. %A Pierangeli, D %A Conti, C. %A Agranat, A.J. %A DelRe, E. %B Phys. Rev. Letters %V 127 %G eng %N 133901 %0 Journal Article %J Nature Communications %D 2021 %T Hyperbolic optics and superlensing in room-temperature KTN from self-induced k-space topological transitions %A Gelkop Y. %A Di Mei, F. %A Frishman, S. %A Garcia, Y. %A Falsi L. %A Perepelitsa, G. %A Conti, C. %A DelRe, E. %A Agranat, A.J. %B Nature Communications %V 12 %G eng %N 7241 %0 Journal Article %J Phys. Rev. Lett. %D 2021 %T Direct observation of fractal-dimensional percolation in the 3D cluster dynamics of a ferroelectric super-crystal %A Falsi L. %A Aversa M. %A Di Mei, F. %A Pierangeli, D %A Xin F. %A Agranat, A.J. %A DelRe, E. %B Phys. Rev. Lett. %V 126 %G eng %N 037601 %0 Journal Article %J Results in Physics %D 2021 %T Enhanced electro-optic effect in potassium lithium tantalate niobate at the paraelectric phase near Tc %A Gilad Hirshfeld %A Yehuda Vidal %A Garcia, Yehudit %A Perepelitsa, Galina %A Avi Karsenty %A Kabessa, Yossef %A Agranat, Aharon J. %B Results in Physics %G eng %N 104059 %0 Conference Proceedings %B SOLID STATE LASERS XXIX: TECHNOLOGY AND DEVICES %D 2020 %T Active Q-switching in Tm:YLF laser based on electro-optic KLTN %A Nahear R. %A Vidal Y. %A Noach S. %A Agranat A. J. %B SOLID STATE LASERS XXIX: TECHNOLOGY AND DEVICES %I Proc. of SPIE %V 11259 %G eng %N 1125932 %0 Journal Article %J New Biotechnology %D 2020 %T Genome-wide gene-deletion screening identifies mutations that significantly enhance explosives vapor detection by a microbial sensor %A Shemer B. %A Shpigel E. %A Gluzman A. %A Yagur-Kroll, S. %A Kabessa, Y. %A Agranat, A.J. %A Belkin S. %B New Biotechnology %V 59 %P 65-73 %G eng %0 Conference Proceedings %B OPTICAL COMPONENTS AND MATERIALS XVII‏ %D 2020 %T Integrated electroholographic photorefractive gratings with sustained longevity by LED illumination %A Agranat A. J. %A Frishman S %A Garcia Y. %A Rosenthal D. %B OPTICAL COMPONENTS AND MATERIALS XVII‏ %I Proc. of SPIE %V 11276 %G eng %N 1127603 %0 Conference Proceedings %B FRONTIERS IN BIOLOGICAL DETECTION: FROM NANOSENSORS TO SYSTEMS XII, %D 2020 %T Bioluminescent bacterial biosensor for large-scale field deployment %A Agranat A. J. %A Kabessa Y %A Shpigel E. %A Shemer B. %A Schwartzglass O. %A Atamneh L. %A Mizrachi Y. %A Uziel Y. %A Ejzenberg M. %A Elad T. %A Belkin S. %B FRONTIERS IN BIOLOGICAL DETECTION: FROM NANOSENSORS TO SYSTEMS XII, %I Proc. of SPIE %V 11258 %G eng %N 112580I %0 Journal Article %J Communications Materials %D 2020 %T Constraint-free wavelength conversion supported by giant optical refraction in a 3D perovskite super-crystal %A Falsi L. %A Tartara L. %A Di Mei, F. %A Flammini, M. %A Parravicini, J. %A Pierangeli, D %A Parravicini G. %A Xin F. %A Di Porto, P %A Agranat, A.J. %A DelRe, E. %B Communications Materials %V 1 %G eng %U https://www.nature.com/articles/s43246-020-00077-z %N 76 %0 Journal Article %J Microbial Biotechnology %D 2020 %T Detection of buried explosives with immobilized bacterial bioreporters %A Benjamin, S. %A Shpigel E. %A Hazan, Carina %A Kabessa, Y. %A Agranat, A.J. %A Belkin S. %B Microbial Biotechnology %G eng %U https://sfamjournals.onlinelibrary.wiley.com/doi/10.1111/1751-7915.13683 %0 Conference Proceedings %B THIN FILMS GROWTH AND DOPING %D 2020 %T Electro-optic pulse generation at the 2µm wavelength range in proximity to the ferroelectric phase transition in KLTN crystals %A Vidal Y. %A Noach S %A Agranat A. J. %B THIN FILMS GROWTH AND DOPING %I Proc. of SPIE %V 11281 %G eng %N 1128159 %0 Journal Article %J Applied Physics %D 2020 %T Evidence of double-loop hysteresis in disordered ferroelectric crystal %A Parravicini J. %A Fornasari L. %A DelRe, E. %A Marabelli, A. %A Agranat, A.J. %A Parravicini G. %B Applied Physics %V 127 %G eng %0 Journal Article %J Applied Physics %D 2020 %T Evidence of double-loop hysteresis in disordered ferroelectric crystal %A Parravicini, J. %A Fornasari L. %A DelRe, E. %A Marabelli, A. %A Agranat, A.J. %A Parravicini G. %B Applied Physics %V 127 %G eng %N 184107 %0 Journal Article %J Physical Review B %D 2020 %T Observation of an exotic lattice structure in transparent KTN perovskite and 3D super-crystals %A Lo Presti L. P. %A Parravicini, J. %A Soave R. %A Parravicini G. %A Mauri M., %A Loconte L. %A Di Mei, F. %A Falsi L. %A Tartara L. %A Binetti S. %A Agranat, A.J. %A DelRe, E. %B Physical Review B %V 102 %G eng %N 214110 %0 Journal Article %J Physical Review B %D 2020 %T Observation of an exotic lattice structure in transparent KTN perovskite and 3D super-crystals %A Lo Presti L. P. %A Parravicini J. %A Soave R. %A Parravicini G. %A Mauri M., %A Loconte L. %A Di Mei F. %A Falsi L. %A Tartara L. %A Binetti S. %A Agranat A. J. %A DelRe E. %B Physical Review B %G eng %0 Journal Article %J Nature Photonics %D 2018 %T Giant refraction across the entire visible spectrum in perovskites %A Di Mei, F. %A Falsi L. %A Flammini, M. %A Pierangeli, D %A Di Porto, P %A Agranat, A.J. %A DelRe, E. %B Nature Photonics %V 12 %G eng %N 734 %0 Journal Article %J Nanoscale %D 2017 %T Liquid–solid directional composites and anisotropic dipolar phases of polar nanoregions in disordered perovskites. %A Parravicini, Jacopo %A DelRe, Eugenio %A Agranat, Aharon J. %A Parravicini, Gianbattista %B Nanoscale %V 9 %P 9572 %8 2017/07/21/ %@ 20403364 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=124094224&site=eds-live %N 27 %! NanoscaleNanoscale %0 Journal Article %J Optics Letters %D 2017 %T Observation of polarization-maintaining light propagation in depoled compositionally disordered ferroelectrics %A Ferraro, M. ( 1,2 ) %A Pierangeli, D. ( 1 ) %A Flammini, M. ( 1 ) %A Di Domenico, G. ( 1,3 ) %A Falsi, L. ( 1 ) %A Di Mei, F. ( 1 ) %A DelRe, E. ( 1,5 ) %A Agranat, A.J. ( 4 ) %B Optics Letters %I OSA - The Optical Society %V 42 %P 3856-3859 %8 2017 / 10 / 01 / %@ 1539479401469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-85030166180&site=eds-live %N 19 %! Optics LettersOptics Letters %0 Journal Article %J Physical Review Applied %D 2017 %T Scalable Electro-Optic Control of Localized Bistable Switching in Broad-Area VCSELs Using Reconfigurable Funnel Waveguides %A Martínez-Lorente, R. ( 1,2 ) %A Delre, E. ( 2 ) %A Parravicini, J. ( 3 ) %A Brambilla, M. ( 4 ) %A Columbo, L. ( 5,6 ) %A Prati, F. ( 7 ) %A Rizza, C. ( 8 ) %A Agranat, A.J. ( 9 ) %B Physical Review Applied %I American Physical Society %V 7 %8 2017 / 06 / 06 / %@ 23317019 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-85020710954&site=eds-live %N 6 %! Physical Review AppliedPhysical Review Applied %0 Journal Article %J Nature Photonics %D 2017 %T Control of light by curved space in nanophotonic structures %A Bekenstein, R. ( 1,2,3 ) %A Sharabi, Y. ( 1 ) %A Tal, O. ( 1 ) %A Segev, M. ( 1 ) %A Kabessa, Y. ( 4 ) %A Agranat, A.J. ( 4 ) %A Engheta, N. ( 5 ) %A Eisenstein, G. ( 6 ) %B Nature Photonics %I Nature Publishing Group %V 11 %P 664-670 %8 2017 / 10 / 01 / %@ 1749489317494885 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-85030260940&site=eds-live %N 10 %! Nature PhotonicsNature Photonics %0 Journal Article %J Optics Letters %D 2017 %T Fast electroholographic wavelength selective switching implemented in a slab waveguide %A Frishman, S. %A Razvag, M. %A Agranat, A.J. %B Optics Letters %I OSA - The Optical Society %V 42 %P 3582-3585 %8 2017 / 09 / 15 / %@ 1539479401469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-85029542268&site=eds-live %N 18 %! Optics LettersOptics Letters %0 Journal Article %J Applied Optics %D 2017 %T Miniaturized photogenerated electro-optic axicon lens Gaussian-to-Bessel beam conversion %A Di Domenico, G. %A DelRe, E. %A Antonacci, G. %A Silvestri, S. %A Parravicini, J. %A Agranat, A.J. %B Applied Optics %I OSA - The Optical Society %V 56 %P 2908-2911 %8 2017 / 04 / 01 / %@ 215531651559128X %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-85016612707&site=eds-live %N 10 %! Applied OpticsApplied Optics %0 Journal Article %J Nature Biotechnology %D 2017 %T Remote detection of buried landmines using a bacterial sensor. %A Belkin, Shimshon %A Yagur-Kroll, Sharon %A Kabessa, Yossef %A Korouma, Victor %A Septon, Tali %A Anati, Yonatan %A Zohar-Perez, Cheinat %A Rabinovitz, Zahi %A Nussinovitch, Amos %A Agranat, Aharon J. %B Nature Biotechnology %I Nature America Publishing %C United States %V 35 %P 308 - 310 %8 2017/04/11 %@ 1546-1696 %G eng %U http://www.nature.com/nbt/journal/v35/n4/full/nbt.3791.html %N 4 %! Nature Biotechnology %0 Journal Article %J Physical Review A: Atomic, Molecular & Optical Physics %D 2016 %T Enhancing optical extreme events through input wave disorder. %A Pierangeli, D %A Musarra, G. %A Di Mei, F. %A Di Domenico, G. %A Agranat, A.J. %A Conti, C. %A DelRe, E. %K Agranat, A. J. %K Conti, C. %K DelRe, E. %K Di Domenico, G. %K Di Mei, F. %K Musarra, G. %K Photorefractive effect %K Physical Review (Periodical) %K Pierangeli, D. %K Rogue waves %K Wave analysis %X

We demonstrate how the emergence of extreme events strongly depends on the correlation length of the input field distribution. Observing the behavior of optical waves in turbulent photorefractive propagation with partially incoherent excitations, we find that rogue waves are strongly enhanced for a characteristic input correlation scale. Waveform analysis identifies this scale with a characteristic peak-intensity-independent wave size, suggesting a general role played by saturation in the nonlinear response in rogue phenomena. [ABSTRACT FROM AUTHOR]Copyright of Physical Review A: Atomic, Molecular & Optical Physics is the property of American Physical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

%B Physical Review A: Atomic, Molecular & Optical Physics %V 94 %P 1 - 1 %8 2016/12// %@ 10502947 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=120813802&site=eds-live %N 6 %! Physical Review A: Atomic, Molecular & Optical Physics %0 Journal Article %J Physical Review Letters %D 2016 %T Intrinsic negative mass from nonlinearityIntrinsic negative mass from nonlinearity %A Di Mei, F. %A Caramazza, P. %A Pierangeli, D %A Di Domenico, G. %A Di Porto, P %A DelRe, E. %A Ilan, H. %A Agranat, A.J. %B Physical Review Letters %I American Physical Society %V 116 %8 2016 / 04 / 14 / %@ 1079711400319007 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-84963815267&site=eds-live %N 15 %! Physical Review LettersPhysical Review Letters %0 Journal Article %J Physical Review B: Condensed Matter & Materials Physics %D 2016 %T Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics. %A Parravicini, Jacopo %A DelRe, Eugenio %A Agranat, Aharon J. %A Parravicini, Gianbattista %K AGRANAT, Aharon J. %K BROKEN symmetry (Physics) %K DELRE, Eugenio %K FERROELECTRIC crystals %K Ferroelectric materials %K LATTICE models (Statistical physics) %K PARRAVICINI, Gianbattista %K PARRAVICINI, Jacopo %K PHYSICS periodicals %X Using temperature-resolved dielectric spectroscopy in the range 25-320 K we investigate the macroscopic response, phase symmetry, and order/disorder states in bulk ferroelectric K1-yLiyTa1-xNbx (KLTN). Four long-range symmetry phases are identified with their relative transitions. Directional analysis of the order/disorder states using Fröhlich entropy indicates global symmetry breaking along the growth axis and an anisotropic dipolar effective thermodynamic behavior, which ranges from disordered to ordered at the same temperature for different directions in the sample. Results indicate that the macroscopic polarization, driven by nanosized polar regions, follows a microscopic perovskite eight-sites lattice model. [ABSTRACT FROM AUTHOR]Copyright of Physical Review B: Condensed Matter & Materials Physics is the property of American Physical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Physical Review B: Condensed Matter & Materials Physics %V 93 %P 1 - 1 %8 2016/03// %@ 10980121 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=117488397&site=eds-live %N 9 %! Physical Review B: Condensed Matter & Materials Physics %0 Journal Article %J Biosensors & Bioelectronics %D 2016 %T Standoff Detection of Buried Landmines Using Genetically Engineered Fluorescent Bacterial Sensors %A Kabessa, Y. %A O. Eyal %A O. Bar-On %A Korouma, V. %A S. Yagur-Kroll %A S. Belkin %A Agranat, A.J. %B Biosensors & Bioelectronics %V 79 %P 784- 788 %G eng %0 Journal Article %J Nature Communications %D 2016 %T Super-crystals in composite ferroelectrics %A Pierangeli, D %A Ferraro, M. ( 1 ) %A Di Mei, F. ( 1,2 ) %A Di Domenico, G. ( 1,2 ) %A Del Re, E. ( 1 ) %A De Oliveira, C.E.M. ( 3 ) %A Agranat, A.J. ( 3 ) %B Nature Communications %I Nature Publishing Group %V 7 %8 2016 / 02 / 24 / %@ 20411723 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-84959422733&site=eds-live %! Nature CommunicationsNature Communications %0 Journal Article %J Physical Review Letters %D 2016 %T Turbulent Transitions in Optical Wave Propagation. %A Pierangeli, D %A Di Mei, F. %A Di Domenico, G. %A Agranat, A.J. %A Conti, C. %A DelRe, E. %X

We report the direct observation of the onset of turbulence in propagating one-dimensional optical waves. The transition occurs as the disordered hosting material passes from being linear to one with extreme nonlinearity. As the response grows, increased wave interaction causes a modulational unstable quasihomogeneous flow to be superseded by a chaotic and spatially incoherent one. Statistical analysis of high-resolution wave behavior in the turbulent regime unveils the emergence of concomitant rogue waves. The transition, observed in a photorefractive ferroelectric crystal, introduces a new and rich experimental setting for the study of optical wave turbulence and information transport in conditions dominated by large fluctuations and extreme nonlinearity.;

%B Physical Review Letters %I American Physical Society %C United States %V 117 %P 183902 - 183902 %8 2016/10/28 %@ 1079-7114 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=cmedm&AN=27834998&site=eds-live %N 18 %! Physical Review Letters %0 Journal Article %J App. Phys. A-Mat. Sci. & Process %D 2015 %T Construction of waveguiding structures in potassium lithium tantalate niobate crystals by combined laser ablation and ion implantation %A Yashar, Ayelet Badichi %A Ilan, Harel %A Agranat, Aharon J. %K Computer science %K Jewish schools %K Lithium compounds %K Microfluidics %K Waveguides %X A generic methodology for constructing complex integrated electro-optic circuits in waveguided configurations is presented. The method is based on combining two techniques, 'laser ablation' and 'refractive index engineering by ion implantations.' The constructed circuits are side-cladded by air trenches that were produced using laser ablation and bottom-cladded by a layer with a reduced refractive index which is generated through the implantation of He.sup.+ ions. This fabrication technique enables the construction of circular structures with complex geometry featuring small radii of curvature, and further can be employed to construct microfluidic channels on the same substrate. The research demonstrates waveguides in both linear and circular configurations that were constructed in a potassium lithium tantalate niobate (KLTN) substrate using the aforementioned method, proving that this substrate is a suitable candidate for use in creating laboratories-on-a-chip with multifunctional capabilities. The proposed techniques used in the research are generic and applicable to a wide range of substrates. %B App. Phys. A-Mat. Sci. & Process %I Springer %V 118 %P 403-407 %8 2015/// %@ 0947-8396 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edsgao&AN=edsgcl.398406950&site=eds-live %N 2 %! Applied Physics A: Materials Science & Processing %0 Journal Article %J Phys. Rev. Lett %D 2015 %T Continuous solitons in lattice nonlinearity %A Pierangeli, D %A M. Flammini %A F Di Mei %A Parravicini, J. %A de Oliveira, C.E.M. %A Agranat, A.J. %A E. Del Re %B Phys. Rev. Lett %V 114 %P 203901 %G eng %N 20 %0 Journal Article %J Journal of Optics %D 2015 %T Miniaturized electro-optic infrared beam-manipulator based on 3D photorefractive funnels. %A Parravicini, J. %A F Di Mei %A Pierangeli, D %A Agranat, A.J. %A DelRe, E. %K BIOMIMETIC materials %K ELECTRO-optical modulation %K MINIATURE electronic equipment %K NEAR infrared spectroscopy %K Photorefractive effect %K SURFACE emitting lasers %X

We demonstrate tunable electro-optic guiding, shaping, and switching of beams in the near infrared spectrum ( 980 nm), typical of VCSEL technology, using biomimetic 3D funnel waveguides miniaturized into a sample of potassium–lithium–tantalate–niobate. The switchable waveguides are written using the slow photorefractive build-up of a 3D volume space-charge field caused by a diffracting continuous wave low intensity λ = 532 nm beam, and electro-optic functionality is supported by the quadratic electro-optic effect of the high-symmetry paraelectric phase. [ABSTRACT FROM AUTHOR]Copyright of Journal of Optics is the property of IOP Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

%B Journal of Optics %V 17 %P 1 - 1 %8 2015/05// %@ 20408978 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=102282746&site=eds-live %N 5 %! Journal of Optics %0 Journal Article %J Physical Review A: Atomic, Molecular & Optical Physics %D 2015 %T Observation of diffraction cancellation for nonparaxial beams in the scale-free-optics regime. %A Di Mei, F. %A Pierangeli, D %A Parravicini, J. %A Conti, C. %A Agranat, A.J. %A DelRe, E. %K OBSERVATION (Scientific method) %K OPTICAL diffraction %K Photorefractive effect %K SCALE-free network (Statistical physics) %K WAVELENGTHS %X We report the observation of diffraction cancellation for visible beams with widths from tens of wavelengths down to fractions of the optical wavelength. The phenomenon is observed at the transition from diffraction- to antidiffraction-dominated beam propagation, triggered by a thermal shock in a photorefractive nanodisordered lithium-enriched potassium-tantalate-niobate (KTN:Li) crystal. Here beams propagate without distortion, independently of intensity and size. Confirming the main prediction of the scale-free-optics model, we find a single unified light behavior that spans across the entire hierarchy of standard optical spatial scales, from wide plane-wave-like beams that obey geometrical optics down to ultranarrow beams with widths of the order of a single wavelength. [ABSTRACT FROM AUTHOR]Copyright of Physical Review A: Atomic, Molecular & Optical Physics is the property of American Physical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Physical Review A: Atomic, Molecular & Optical Physics %V 92 %P 1 - 5 %8 2015/07/15/ %@ 10502947 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=108999818&site=eds-live %N 1-B %! Physical Review A: Atomic, Molecular & Optical Physics %0 Conference Paper %B QELS Fundamental Science %D 2015 %T Observing Light Dynamics in Micro-sized Schwarzschild Metric %A R. Bekenstein %A Kabessa, Y. %A O. Tal %A M. A. Bandres %A Agranat, A.J. %A Segev, M. %B QELS Fundamental Science %P FTu4C.2 %G eng %0 Journal Article %J Optics express %D 2015 %T

Electro-Optical Modulation with Immunity to Optical Damage by Bipolar Operation in Potassium Lithium Tantalate Niobate

%A Kabessa, Yossef %A Amir Yativ %A Ilan, Harel %A Agranat, Aharon J. %X A method for suppressing the formation of optical damage in quadratic electrooptic devices operated at short wavelengths is presented. Formation of optical damage is attributed to the generation of a trapped space charge induced by photoionization of impurity ions by the propagating beam. It is shown that in potassium lithium tantalate niobate where the electrooptic effect is quadratic, operating the electrooptic device by a bipolar driving voltage prevents the space charge from accumulating, which inhibits the formation of the optical damage. A 6 hours continuous operation of electrooptic modulator for a 30 W/cm2 at λ = 445 nm input beam is demonstrated. %B Optics express %V 23 %P 4348-4356 %G eng %N 4 %0 Journal Article %J Physical Review Letters %D 2015 %T Spatial Rogue Waves in Photorefractive Ferroelectrics %A Pierangeli, D. ( 1 ) %A Di Mei, F. ( 1,2 ) %A Conti, C. ( 1,3 ) %A Del Re, E. ( 1 ) %A Agranat, A.J. ( 4 ) %X

Rogue waves are observed as light propagates in the extreme nonlinear regime that occurs when a photorefractive ferroelectric crystal is undergoing a structural phase transition. The transmitted spatial light distribution contains bright localized spots of anomalously large intensity that follow a signature long-tail statistics that disappears as the nonlinearity is weakened. The isolated wave events form as out-of-equilibrium response and disorder enhance the Kerr-saturated nonlinearity at the critical point. Self-similarity associable to the individual observed filaments and numerical simulations of the generalized nonlinear Schrodinger equation suggests that dynamics of soliton fusions and scale invariance can microscopically play an important role in the observed rogue intensities and statistics.

%B Physical Review Letters %I American Physical Society %V 115 %8 2015 / 08 / 25 / %@ 1079711400319007 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-84940688543&site=eds-live %N 9 %! Physical Review LettersPhysical Review Letters %0 Journal Article %J Nature Photonics %D 2015 %T Subwavelength anti-diffracting beams propagating over more than 1,000 Rayleigh lengths %A DelRe, E. %A Di Mei, F. %A Parravicini, J. %A Conti, C. %A Parravicini, G. %A Agranat, A.J. %B Nature Photonics %I Nature Publishing Group %V 9 %P 228-232 %8 2015 / 03 / 31 / %@ 1749489317494885 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-84926333767&site=eds-live %N 4 %! Nature PhotonicsNature Photonics %0 Journal Article %J Optics Letters %D 2015 %T Volume integrated phase modulator based on funnel waveguides for reconfigurable miniaturized optical circuits. %A Parravicini, J. %A Martínez Lorente, R %A Di Mei, F. %A Pierangeli, D %A Agranat, A.J. %A DelRe, E. %X

We demonstrate the integration of a miniaturized 30(x)  μm×30(y)  μm×2.7(z)  mm electro-optic phase modulator operating in the near-IR (λ=980  nm) based on the electro-activation of a funnel waveguide inside a paraelectric sample of photorefractive potassium lithium tantalate niobate. The modulator forms a basic tassel in the realization of miniaturized reconfigurable optical circuits embedded in a single solid-state three-dimensional chip.;

%B Optics Letters %I Optical Society of America %C United States %V 40 %P 1386 - 1389 %8 2015/04/01 %@ 1539-4794 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=cmedm&AN=25831339&site=eds-live %N 7 %! Optics Letters %0 Journal Article %J OPTICAL MATERIALS EXPRESS %D 2014 %T Observation of an intrinsic nonlinearity in the electro-optic response of freezing relaxors ferroelectrics %A Pierangeli, D %A Di Mei, F. %A Parravicini, J. %A Parravicini, GB %A Agranat, A.J. %A Conti, C. %A DelRe, E. %K MATERIALS SCIENCE, MULTIDISCIPLINARY %K Optics %X

We demonstrate an electro-optic response that is linear in the amplitude but independent of the sign of the applied electric field. The symmetry-preserving linear electro-optic effect emerges at low applied electric fields in freezing nanodisordered KNTN above the dielectric peak temperature, deep into the nominal paraelectric phase. Strong temperature dependence allows us to attribute the phenomenon to an anomalously reduced thermal agitation in the reorientational response of the underlying polar-nanoregions. (C) 2014 Optical Society of America

%B OPTICAL MATERIALS EXPRESS %V 4 %P 1487 - 1493 %8 AUG 1, 2014 %@ 21593930 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000341647900001&site=eds-live %N 8 %! OPTICAL MATERIALS EXPRESS %0 Journal Article %J Optics Express %D 2014 %T Anti-diffracting beams through the diffusive optical nonlinearity. %A Di Mei, F. %A Parravicini, J. %A Pierangeli, D %A Conti, C. %A Agranat, A.J. %A DelRe, E. %X

Anti-diffraction is a theoretically predicted nonlinear optical phenomenon that occurs when a light beam spontaneously focalizes independently of its intensity. We observe anti-diffracting beams supported by the peak-intensity-independent diffusive nonlinearity that are able to shrink below their diffraction-limited size in photorefractive lithium-enriched potassium-tantalate-niobate (KTN:Li).;

%B Optics Express %I Optical Society of America %C United States %V 22 %P 31434 - 31439 %8 2014/12/15 %@ 1094-4087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=cmedm&AN=25607093&site=eds-live %N 25 %! Optics Express %0 Journal Article %J Physical Review. E, Statistical, Nonlinear, And Soft Matter PhysicsPhys Rev E Stat Nonlin Soft Matter Phys %D 2014 %T Circular polarization induced by the three-dimensional chiral structure of human sweat ducts. %A Hayut, Itai %A Ishai, Paul Ben %A Agranat, Aharon J. %A Feldman, Yuri %K Circular Dichroism* %K Computer Simulation %K Electric Impedance %K Galvanic Skin Response/*physiology %K Humans %K Models, Biological* %K Sweat Glands/*anatomy & histology %K Sweat Glands/*physiology %X The upper part of the human eccrine sweat ducts, embedded within the epidermis layer, have a well-defined helical structure. It was recently suggested that, as electromagnetic entities, the sweat ducts interact with sub-mm waves [Y. Feldman et al., Phys. Rev. Lett. 100, 128102 (2008)]. Although correlation between changes in the reflectance spectrum in this frequency range and physiological activities has been shown, a direct link between the electromagnetic reflection and the helical structure itself has remained to be established. The fact that the sweat ducts manifest natural homochirality is henceforth used to produce this link. We report the detection of circular polarization asymmetry in the electromagnetic reflection from the human skin at sub-THz frequencies in vivo. We compare the results to numerical simulations and to measurements of a fabricated metamaterial. We argue that the observed circular dichroism can be interpreted uniquely as the signature of the helical structure itself. By twisting reflected electromagnetic waves, the human skin exhibits properties which are usually discussed only in the framework of metamaterial science.; %B Physical Review. E, Statistical, Nonlinear, And Soft Matter PhysicsPhys Rev E Stat Nonlin Soft Matter Phys %I Published by the American Physical Society through the American Institute of Physics %C United States %V 89 %P 042715 - 042715 %8 2014/04 %@ 1550-2376 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=cmedm&AN=24827286&site=eds-live %N 4 %! Physical Review. E, Statistical, Nonlinear, And Soft Matter Physics %0 Journal Article %J European Physical Journal B %D 2014 %T Multivariate pressure effects on an electron hopping process in ferroelectric K[Ta.sub.1-x][Nb.sub.x][O.sub.3] %A Lerner, Shimon E. %A Feldman, Yuri %A Mierzwa, Michal %A Paluch, Marian %A Agranat, Aharon J. %A Ishai, Paul Ben %K Activation energy -- Electric properties %K Dielectrics -- Electric properties %K Electrical conductivity -- Electric properties %B European Physical Journal B %I Springer %V 7 %8 2014/// %@ 1434-6028 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edsgao&AN=edsgcl.386613351&site=eds-live %N 158 %! The European Physical Journal B - Condensed Matter and Complex Systems %0 Journal Article %J Optics Express %D 2014 %T Observation of electro-activated localized structures in broad area VCSELs. %A Parravicini, J. %A Brambilla, M %A Columbo, L %A Prati, F %A Rizza, C %A Tissoni, G %A Agranat, A.J. %A DelRe, E. %X

We demonstrate experimentally the electro-activation of a localized optical structure in a coherently driven broad-area vertical-cavity surface-emitting laser (VCSEL) operated below threshold. Control is achieved by electro-optically steering a writing beam through a pre-programmable switch based on a photorefractive funnel waveguide.;

%B Optics Express %I Optical Society of America %C United States %V 22 %P 30225 - 30233 %8 2014/12/01 %@ 1094-4087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=cmedm&AN=25606953&site=eds-live %N 24 %! Optics Express %0 Journal Article %J Applied Physics B - Lasers and Optics %D 2014 %T

A Bragg grating embedded in a slab waveguide fabricated by the implantation of high-energy light ions in KLTN substrate

%A Frishman, Sagi %A Gumennik, Alexander %A Ilan, Harel %A Agranat, Aharon J. %K Architecture -- Electric properties %K Computer science -- Electric properties %K Lithium compounds -- Electric properties %K Waveguides -- Electric properties %X Electro-optically tunable transmission grating was imprinted in potassium lithium tantalate niobate by irreversible spatial patterning of the dielectric constant. While embedded into waveguided architecture, it provides a reliable and versatile building block for opto-electronic circuitry, capable of both active switching and multiplexing. Realization of such a block is critical for the fabrication of integrated photonic circuits in electro-optic substrates by means of Refractive Index Engineering by fast ion implantation. %B Applied Physics B - Lasers and Optics %I Springer %V 115 %P 143-147 %8 2014/// %@ 0946-2171 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edsgao&AN=edsgcl.361133533&site=eds-live %N 1 %! Applied Physics B: Lasers and Optics %0 Generic %D 2014 %T Photorefractive light needles in glassy nanodisordered KNTN %A Pierangeli, D %A Parravicini, J. %A Di Mei, F. %A Parravicini, GB %A Agranat, A.J. %A DelRe, E. %K Optics %X

We study the formation of 2D self-trapped beams in nanodisordered potassium-sodium-tantalate-niobate (KNTN) cooled below the dynamic glass transition. Supercooling is shown to accelerate the photorefractive response and enhance steady-state anisotropy. Effects in the excited state are attributed to the anomalous slim-loop polarization curve typical of relaxors dominated by non-interacting polar-nano-regions. (C) 2014 Optical Society of America

%B Optics Letters %V 39 %P 1657 - 1660 %8 MAR 15, 2014 %@ 01469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000332943800082&site=eds-live %N 6 %! OPTICS LETTERS %0 Journal Article %J Optics Express %D 2013 %T Aging solitons in photorefractive dipolar glasses. %A Parravicini, J. %A Pierangeli, D %A Di Mei, F. %A Conti, C. %A Agranat, A.J. %A DelRe, E. %X

We study experimentally the aging of optical spatial solitons in a dipolar glass hosted by a nanodisordered sample of photorefractive potassium-sodium-tantalate-niobate (KNTN). As the system ages, the waves erratically explore varying strengths of the nonlinear response, causing them to break up and scatter. We show that this process can still lead to solitons, but in a generalized form for which the changing response is compensated by changing the normalized wave size and intensity so as to maintain fixed the optical waveform.;

%B Optics Express %I Optical Society of America %C United States %V 21 %P 30573 - 30579 %8 2013/12/16 %@ 1094-4087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=cmedm&AN=24514634&site=eds-live %N 25 %! Optics Express %0 Journal Article %J Optics Letters %D 2013 %T

Full C-Band Tunable Laser based on Electroholography

%A Noam Sapiens %A Agranat, Aharon J. %X A tunable laser that spans the entire C band is presented. The laser consists of an Er-doped fiber amplifier gain medium, a fiber ring resonator, and an electroholography-based tuning mechanism. The electrohologram used is in the g44 configuration where the Bragg condition can be electrically tuned for a specific wavelength. Two laser architectures are presented, one in which the diffracting beam and one in which the direct beam of the electrohologram is used as the laser output. Switching time between wavelengths is limited by the gain medium relaxation time, since the electrohologram switching time is less than 1 ns. %B Optics Letters %V 38 %P 2131-2133 %G eng %0 Journal Article %J IEEE Transactions on Terahertz Science and Technology %D 2013 %T The helical structure of sweat ducts: Their influence on the electromagnetic reflection spectrum of the skin %A Hayut, I. %A Puzenko, A. %A Ben Ishai, P. %A Polsman, A. %A Agranat, A.J. %A Feldman, Y. %K Electromagnetic (EM) simulations %K skin %K sub-mm wave band %K sweat ducts %B IEEE Transactions on Terahertz Science and Technology %V 3 %P 207-215 %8 2013 / 01 / 01 / %@ 2156342X %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-84874988433&site=eds-live %N 2 %! IEEE Transactions on Terahertz Science and TechnologyIEEE Transactions on Terahertz Science and Technology %0 Journal Article %J Optics Express %D 2013 %T

A sub wavelength localization scheme in optical imaging using conical diffraction

%A Shani Rosen %A Gabriel Y. Sirat %A Ilan, Harel %A Agranat, Aharon J. %X In this paper we present a scheme for the acquisition of high temporal resolution images of single particles with enhanced lateral localization accuracy. The scheme, which is implementable as a part of the illumination system of a standard confocal microscope, is based on the generation of a vector beam that is manipulated by polarimetry techniques to create a set of illumination PSFs with different spatial profiles. The combination of data collected in different illumination states enables the extraction of spatial information obscured by diffraction in the standard imaging system. An implementation of the scheme based on the utilization of the unique phenomenon of conical diffraction is presented, and the basic strategy it provides for enhanced localization in the diffraction limited region is demonstrated. %B Optics Express %V 21 %P 101338 %G eng %N 8 %0 Journal Article %J Biosensors & Bioelectronics %D 2013 %T

Simultaneous quantification of the fluorescent responses of an ensemble of bacterial sensors.

%A Kabessa, Yossef %A Korouma, Victor %A Ilan, Harel %A Yagur-Kroll, Sharon %A Belkin, Shimshon %A Agranat, Aharon J. %K Bacterial whole-cell biosensors %K BIOSENSORS %K Fluorescence %K FLUORIMETRY %K GENETIC toxicology %K GFP reporter gene %K IDENTIFICATION of bacteria %K PHOTODETECTORS %K RECOMBINANT microorganisms %K Simultaneous sampling %X Abstract: Bacterial bioreporters are genetically engineered microbial strains capable of detecting specific chemicals, groups of chemicals or global biological effects such as toxicity or genotoxicity. A scheme for simultaneous selective detection of the fluorescent signals emitted by a bacterial biosensor array, able to detect four different types of toxicants, using a single photodetector (photomultiplier) is presented. The underlying principle of the scheme is to convert the spatially distributed signals from all the elements in the array to temporally distributed frequency multiplexed signals at the output of the photodetector. Experimental proof of this concept is demonstrated in a four-channel system, in which low power (a few tens of picowatts) fluorescent signals produced by the bacterial sensors are measured, while maintaining a wide dynamic range of detection (more than 3 orders of magnitude). Simultaneous monitoring of concentrations down to a few mg/l of different chemicals in a liquid sample is demonstrated. [Copyright &y& Elsevier]Copyright of Biosensors & Bioelectronics is the property of Elsevier Science Publishing Company, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Biosensors & Bioelectronics %V 49 %P 394 - 398 %8 2013/11/15/ %@ 09565663 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=89435767&site=eds-live %! Biosensors & Bioelectronics %0 Journal Article %J Applied Physics Letters %D 2012 %T Equalizing disordered ferroelectrics for diffraction cancellation %A Parravicini, J. %A Conti, C. %A DelRe, E. %A Agranat, A.J. %B Applied Physics Letters %V 101 %8 2012 / 09 / 10 / %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-84866336071&site=eds-live %N 11 %! Applied Physics LettersApplied Physics Letters %0 Generic %D 2012 %T Funnel-based biomimetic volume optics %A DelRe, E. %A Pierangelo, A. %A Parravicini, J. %A Gentilini, S %A Agranat, A.J. %K Optics %X

We demonstrate the use of three-dimensional funnel index of refraction patterns analogous to those of retinal Muller cells as support for tunable and multi-functional volume optical component miniaturization and integration. Our experiments in paraelectric photorefractive crystals show how a single funnel can act both as a waveguide and a tunable focusing/defocusing micro-lens. Pairing multiple funnel patterns, we are also able to demonstrate ultra-compact tunable beam-splitting, with distinct guided output modes in under 1mm of propagation. (C) 2012 Optical Society of America

%B Optics Express %V 20 %P 16631 - 16638 %8 JUL 16, 2012 %@ 10944087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000307055800048&site=eds-live %N 15 %! OPTICS EXPRESS %0 Journal Article %J Applied Physics Letters %D 2012 %T

Electrically controlled absorption in a slab waveguide formed by the implantation of protons in a potassium lithium tantalate niobate substrate.

%A Ilan, Harel %A Agranat, Aharon J. %K LITHIUM tantalate %K POTASSIUM %K PROTONS %K SUBSTRATES (Materials science) %K Waveguides %X Electrically controlled absorption was observed in a slab waveguide, fabricated in a potassium lithium tantalate niobate substrate by proton implantation, at an energy of E=1.15 MeV and a fluence of 6.1×1016ions/cm2. The implantation created an amorphous layer which acted as the cladding with an adjacent proton doped layer at its bottom. It is suggested that a n-i junction is formed at the interface between the proton layer and the substrate, which is the core of the waveguide. The electrically controlled absorption is attributed to changes in the width of the depletion area of the n-i junction induced by the applied field. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Applied Physics Letters %I American Institute of Physics %V 101 %P 261101 %8 2012/12/24/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=84623481&site=eds-live %N 26 %! Applied Physics Letters %0 Journal Article %J Applied Physics Letters %D 2012 %T

Investigation of the conduction in an implanted layer of protons in a potassium lithium tantalate niobate substrate.

%A Ilan, Harel %A Frishman, Sagi %A Agranat, Aharon J. %K ELECTRIC conductivity -- Research %K LITHIUM niobate %K LITHIUM tantalate %K POTASSIUM niobate %K PROTONS %K SUBSTRATES (Materials science) %X The electrical conductivity in the amorphous layer formed by the implantation of protons at 1.15 MeV with fluence of 1.1×1017 ions/cm2 within the depth of potassium lithium tantalate niobate is investigated by four probes and Hall effect measurements. It is shown that the conductivity originates from electrons that are induced by 'Hydrogen donors' that reside in a band structure 0.22 eV below the conduction band. It is claimed that this phenomenon enables the construction of conductive structures with submicron features within the depth of the substrate that can be used as embedded electrodes in electrooptical devices integrated in this substrate. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Applied Physics Letters %I American Institute of Physics %V 101 %P 141111 %8 2012/10//10/1/20 %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=82303241&site=eds-live %N 14 %! Applied Physics Letters %0 Journal Article %J Optics Letters %D 2012 %T Programming scale-free optics in disordered ferroelectrics. %A Parravicini, Jacopo %A Conti, Claudio %A Agranat, Aharon J. %A DelRe, Eugenio %X

Using the history dependence of a dipolar glass hosted in a compositionally disordered lithium-enriched potassium tantalate niobate (KTN:Li) crystal, we demonstrate scale-free optical propagation at tunable temperatures. The operating equilibration temperature is determined by previous crystal spiralling in the temperature/cooling-rate phase space.;

%B Optics Letters %I Optical Society of America %C United States %V 37 %P 2355 - 2357 %8 2012/06/15 %@ 1539-4794 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=cmedm&AN=22739906&site=eds-live %N 12 %! Optics Letters %0 Generic %D 2012 %T Rejuvenation in scale-free optics and enhanced diffraction cancellation life-time %A Parravicini, J. %A Conti, C. %A Agranat, A.J. %A DelRe, E. %K Optics %X

We demonstrate rejuvenation in scale-free optical propagation. The phenomenon is caused by the non-ergodic relaxation of the dipolar glass that mediates the photorefractive nonlinearity in compositionally-disordered lithium-enriched potassium-tantalate-niobate (KTN:Li). We implement rejuvenation to halt aging in the dipolar glass and extend the duration of beam diffraction cancellation. (C) 2012 Optical Society of America

%B Optics Express %V 20 %P 27382 - 27387 %8 NOV 19, 2012 %@ 10944087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000312452800128&site=eds-live %N 24 %! OPTICS EXPRESS %0 Generic %D 2012 %T The remote sensing of mental stress from the electromagnetic reflection coefficient of human skin in the sub-THz range %A Safrai, E %A Ben Ishai, P. %A Caduff, A. %A Puzenko, A. %A Polsman, A. %A Agranat, A.J. %A Feldman, Y. %K Antennas %K BIOLOGY %K Biophysics %K Epidermis %K Human skin %K Mental stress %K Reflection coefficient %K Stroop effect %K sweat ducts %X Recent work has demonstrated that the reflection coefficient of human skin in the frequency range from 95 to 110?GHz (W band) mirrors the temporal relaxation of stress induced by physical exercise. In this work, we extend these findings to show that in the event of a subtle trigger to stress, such as mental activity, a similar picture of response emerges. Furthermore, the findings are extended to cover not only the W band (75-110?GHz), but also the frequency band from 110 to 170?GHz (D band). We demonstrate that mental stress, induced by the Stroop effect and recorded by the galvanic skin response (GSR), can be correlated to the reflection coefficient in the aforementioned frequency bands. Intriguingly, a light physical stress caused by repeated hand gripping clearly showed an elevated stress level in the GSR signal, but was largely unnoted in the reflection coefficient in the D band. The implication of this observation requires further validation. Bioelectromagnetics 33:375382, 2012. (C) 2011 Wiley Periodicals, Inc. %B Bioelectromagnetics %V 33 %P 375 - 382 %8 JUL, 2012 %@ 01978462 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000304750800003&site=eds-live %N 5 %! BIOELECTROMAGNETICS %0 Generic %D 2011 %T Diffraction cancellation over multiple wavelengths in photorefractive dipolar glasses %A Parravicini, J. %A Di Mei, F. %A Conti, C. %A Agranat, A.J. %A DelRe, E. %K Optics %X

We report the simultaneous diffraction cancellation for beams of different wavelengths in out-of-equilibrium dipolar glass. The effect is supported by the photorefractive diffusive nonlinearity and scale-free optics, and can find application in imaging and microscopy. (C) 2011 Optical Society of America

%B Optics Express %V 19 %P 24109 - 24114 %8 NOV 21, 2011 %@ 10944087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000298322000048&site=eds-live %N 24 %! OPTICS EXPRESS %0 Journal Article %J Applied Physics A - Materials Science & Processing %D 2011 %T

Construction of conducting and photoconducting 3D structures with submicron resolution in electrooptical substrates

%A Siman-Tov, Heli %A Gumennik, Alexander %A Ilan, Harel %A Mazursky, Noa %A Agranat, Aharon J. %K Computer science %X It is shown that the implantation of protons in electrooptical substrates enables the construction of 3D structures with submicron features that are both conductive and photoconductive embedded in amorphized regions that possess reduced refractive index. The conductivity and photoconductivity are attributed to the transformation of the material into a degenerate semiconductor due to the formation of high concentration of OH.sup.- complexes that are created by the bonding of the implanted H.sup.+ ions to the O.sup.-2 ions of the lattice. It is argued that these results extend significantly the capabilities of integrated photonic circuits and devices fabricated by Refractive Index Engineering by ion implantations. %B Applied Physics A - Materials Science & Processing %I Springer %V 102 %P 45-48 %8 2011/// %@ 0947-8396 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edsgao&AN=edsgcl.246178061&site=eds-live %N 1 %! Applied Physics A: Materials Science & Processing %0 Journal Article %J Optical Materials Express %D 2011 %T

Electrooptical effects in glass forming liquids of dipolar nano-clusters embedded in a paraelectric environment

%A Gumennik, A. %A Kurzweil-Segev, Y. %A Agranat, A.J. %X Studies of the electrooptic effect in potassium tantalate niobate (KTN) and Li doped KTN in the vicinity of the ferroelectric phase transition are reported. It was observed that in KTN the standard electrooptic behavior is accompanied by electrically induced depolarization of the light traversing through the crystal. This behavior is attributed to the influence of the fluctuating dipolar clusters that are formed in KTN above the ferroelectric phase transition due to the emergence of the Nb ions out of the center of inversion of the unit cell. It was shown in addition that this behavior is inhibited in Li doped KTN, which enables exploiting the large electrooptic effect in these crystals. %B Optical Materials Express %V 1 %P 803-815 %G eng %N 5 %0 Journal Article %J Nature Photonics %D 2011 %T Scale-free optics and diffractionless waves in nanodisordered ferroelectrics. %A DelRe, E. %A Spinozzi, E. %A Agranat, A.J. %A Conti, C. %K FERROELECTRIC crystals %K Microscopy %K OPTICAL diffraction %K Optics %K Solitons %X

Wavelength rigidly fixes the diffraction that distorts waves during propagation, and poses fundamental limits to imaging, microscopy and communication. This distortion can be avoided by using waveguides or nonlinearity to produce solitons. In both cases, however, diffraction is only compensated, so the wavelength still imposes rigid laws on wave shape, size and soliton intensity. Nonlinearity, in turn, can introduce new spatial scales. In principle, if one is able to identify a nonlinearity that introduces an intensity-independent scale that cancels the wavelength, 'scale-free' propagation can occur. In this regime, diffraction ceases, and waveforms will naturally propagate without distortion, forming solitons of any size and intensity, even arbitrarily low. Here we provide the first experimental evidence of scale-free optical propagation in supercooled copper-doped KTN:Li, a recently developed out-of-equilibrium ferroelectric. This demonstrates that diffraction can be cancelled, and not merely compensated, thus leading to a completely new paradigm for ultraresolved imaging and microscopy. [ABSTRACT FROM AUTHOR]Copyright of Nature Photonics is the property of Nature Publishing Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

%B Nature Photonics %V 5 %P 39 %8 2011/01// %@ 17494885 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=56512313&site=eds-live %N 1 %! Nature PhotonicsNature Photonics %0 Journal Article %J Physical Review A: Atomic, Molecular & Optical Physics %D 2011 %T Subwavelength optical spatial solitons and three-dimensional localization in disordered ferroelectrics: Toward metamaterials of nonlinear origin. %A Conti, C. %A Agranat, A.J. %A DelRe, E. %K FERROELECTRIC crystals %K IMAGING systems %K METAMATERIALS %K OPTICAL disk drives %K Solitons %K WAVELENGTHS %X

We predict the existence of a class of multidimensional light localizations in out-of-equilibrium ferroelectric crystals. In two dimensions, the nondiffracting beams form at an arbitrary low-power level and propagate even when their width is well below the optical wavelength. In three dimensions, a subwavelength light bullet is found. The effects emerge when compositionally disordered crystals are brought to their metastable glassy state, and leading to the suppression of evanescent waves, they can have a profound impact on super-resolved imaging and ultradense optical storage, resembling metamaterials in many ways. [ABSTRACT FROM AUTHOR]Copyright of Physical Review A: Atomic, Molecular & Optical Physics is the property of American Physical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

%B Physical Review A: Atomic, Molecular & Optical Physics %V 84 %P 043809-1 - 043809-4 %8 2011/10/15/ %@ 10502947 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=70317274&site=eds-live %N 4-B %! Physical Review A: Atomic, Molecular & Optical Physics %0 Generic %D 2009 %T Electro-activation and electro-morphing of photorefractive funnel waveguides %A Pierangelo, A. %A Ciattoni, A. %A Palange, E. %A Agranat, A.J. %A DelRe, E. %K Optics %X

We demonstrate the electro-activation of funnel waveguides through the quadratic electro-optic effect in paraelectric potassium-lithium-tantalate- niobate. This allows us to achieve electro-optic intensity modulation in a single optical beam, a 1x2 switch, and finally the electrically controlled morphing of a single waveguide into a 1x2 and a 1x4 divider. (C) 2009 Optical Society of America

%B Optics Express %V 17 %P 22659 - 22665 %8 DEC 7, 2009 %@ 10944087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000272761300042&site=eds-live %N 25 %! OPTICS EXPRESS %0 Journal Article %J Physics in Medicine and Biology %D 2009 %T The electromagnetic response of human skin in the millimetre and submillimetre wave range %A Feldman, Y. %A Puzenko, A. %A Ben Ishai, P. %A Caduff, A. %A Davidovich, I. %A Sakran, F. %A Agranat, A.J. %B Physics in Medicine and Biology %V 54 %P 3341-3363 %8 2009 / 01 / 01 / %@ 0031915513616560 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-69249232347&site=eds-live %N 11 %! Physics in Medicine and BiologyPhysics in Medicine and Biology %0 Journal Article %J Optics Letters %D 2009 %T

Fast Electroholographic Switching

%A Sapiens, N. %A Weissbrod, A. %A Agranat, A.J. %X Electroholographic switching with a rise time of 13 ns is henceforth presented. The switching was demonstrated in a potassium lithium tantalate crystal doped with copper and titanium with Tc=10 degrees C. The crystal was operated at 17 degrees C. The switching operation was done in the g11/g12 configuration, in which the Bragg condition remains fulfilled at all levels of the applied field. As electroholography is a wavelength-selective switching method, this opens the way for implementing optical packet switching and fast wavelength addressing schemes in optical fiber networks that apply wavelength division multiplexing. %B Optics Letters %V 34 %P 353-355 %G eng %N 3 %0 Journal Article %J Optics Express %D 2009 %T

A tunable channel waveguide array fabricated by the implantations of Heions in an electrooptical KLTN substrate

%A Gumennik, A. %A Perepelitsa, G. %A Israel, A. %A Agranat, A.J. %X An electrooptical channel waveguide array was constructed in potassium lithium tantalate niobate substrate by the implantation of He+ ions at high energies. The array was fabricated by two successive implantation sessions at 1.6 MeV and 1.2 MeV through a comb-like stopping mask that limited the implanted ions to penetrate the substrate in 1 ?m wide stripes periodically distributed at 3.5 ?m intervals. This generated a grating of amorphized stripes with reduced refractive index. This was followed by a uniform implantation of He+ ions at 1.8 MeV which created a bottom cladding layer below the array. Wave propagation in the array was studied by focusing a light beam at 636 nm into the central channel, and observing the wavefront it created at the output plane of the array. It was found that applying an electric field across the array strongly affects the coupling between adjacent channels and governs the width of the wavefront at the output plane. %B Optics Express %V 17 %P 5919-6251 %G eng %N 8 %0 Journal Article %J Physical Review Letters %D 2008 %T Human skin as arrays of helical antennas in the millimeter and submillimeter wave range %A Feldman, Y. %A Puzenko, A. %A Ben Ishai, P. %A Caduff, A. %A Agranat, A.J. %B Physical Review Letters %V 100 %8 2008 / 03 / 27 / %@ 0031900710797114 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-41549168686&site=eds-live %N 12 %! Physical Review LettersPhysical Review Letters %0 Journal Article %J Journal of Optics A: Pure and Applied Optics %D 2008 %T Linear writing of waveguides in bulk photorefractive crystals through a two-step polarization sequence %A Pierangelo, A. %A DelRe, E. %A Palange, E. %A Ciattoni, A. %A Crosignani, B.) %A Agranat, A.J. %K Optical waveguides %K Photorefraction %K Spatial solitons %B Journal of Optics A: Pure and Applied Optics %V 10 %8 2008 / 06 / 01 / %@ 1464425817413567 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-44449142523&site=eds-live %N 6 %! Journal of Optics A: Pure and Applied OpticsJournal of Optics A: Pure and Applied Optics %0 Journal Article %J Applied Physics Letters %D 2008 %T

Construction of an optical wire imprinted in potassium lithium tantalate niobate by He+ implantation.

%A Ilan, Harel %A Gumennik, Alexander %A Perepelitsa, Galina %A Israel, Abraham %A Agranat, Aharon J. %K ELECTROOPTICS %K INTEGRATED circuits %K Ion implantation %K POTASSIUM compounds %K Waveguides %K WIRE %X A channel waveguide constructed in potassium lithium tantalate niobate (KLTN) substrate by the implantation of He+ ions at 1.65 MeV is presented. The waveguide has a trapezoidal profile with a crystalline KLTN core surrounded by amorphized KLTN created by the implantation. The implantation was done through a 2 μm thick gold stopping mask with a trapezoidal groove. During the implantation, the contour of the groove was replicated beneath the surface of the substrate forming the trapezoidal cladding of the channel waveguide. The channel waveguide is designed as the interconnecting element in electro-optical integrated circuits. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Applied Physics Letters %V 92 %P 192101 %8 2008/05/12/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=33547454&site=eds-live %N 19 %! Applied Physics LettersApplied Physics Letters %0 Generic %D 2008 %T Photorefractive solitons of arbitrary and controllable linear polarization determined by the local bias field %A D'Ercole, A. %A Pierangelo, A. %A Palange, E. %A Ciattoni, A. %A Agranat, A.J. %A DelRe, E. %K Optics %X

We discuss and experimentally demonstrate a scheme to achieve photorefractive solitons of arbitrary linear polarization using the quadratic electro-optic effect and describe the observation of the self-trapping of a set of linear polarized beams in different positions of a paraelectric photorefractive crystal of potassium-lithium-tantalate-niobate (KLTN) biased by the inhomogeneous field produced by two miniaturized top electrodes. The polarization of the single solitons of the set is determined by the local electrostatic configuration and the underlying tunable anisotropy, which is detected through zero-field electro-activation. (C) 2008 Optical Society of America.

%B Optics Express %V 16 %P 12002 - 12007 %8 AUG 4, 2008 %@ 10944087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000258368600037&site=eds-live %N 16 %! OPTICS EXPRESS %0 Journal Article %J Applied Physics Letters %D 2007 %T Beam shaping and effective guiding in the bulk of photorefractive crystals through linear beam dynamics. %A DelRe, E. %A Pierangelo, A. %A Palange, E. %A Ciattoni, A. %A Agranat, A.J. %K BEAM dynamics %K CRYSTALS %K NONLINEAR optics %K PHOTOREFRACTIVE materials %K Waveguides %X The authors demonstrate a technique to optically imprint through linear beam propagation an index pattern in the bulk of a photorefractive crystal capable of beam reshaping and waveguiding. The procedure is based on the separation into two distinct phases of the photosensitive and refractive response, so that light is in all cases undergoing only linear propagation. When saturation in the response becomes dominant, the scheme is able to achieve both one-dimensional and two-dimensional waveguiding. The result allows the straightforward writing of multiwaveguide circuits, where traditional schemes based on spatial solitons are in practice burdened by nonlinearity. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Applied Physics Letters %I American Institute of Physics %V 91 %P 081105 %8 2007/08/20/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=27758753&site=eds-live %N 8 %! Applied Physics Letters %0 Journal Article %J Applied Optics %D 2007 %T

Design methodology of refractive index engineering by implantation of high-energy particles in electro-optic materials

%A Gumennik, Alexander %A Ilan, Har'el %A Fathei, Roei %A Israel, Abraham %A Agranat, Aharon J. %A Shachar, Igal %A Hass, Michael %K Photorefractive materials -- Design and construction %K Refractive index -- Analysis %K United States %X Slab waveguides were constructed in [K.sub.1-x]-[Li.sub.x][Ta.sub.1-y] [Nb.sub.y][O.sub.3] crystals by the implantation of [sup.12][C.sup.+4] ions at 30 MeV and [sup.16][O.sup.+5] ions at 30 and 40 MeV. The waveguides were characterized by a prism coupler setup. A refractive index drop of 10.9% was observed in a layer formed by the implantation of [sup.16][O.sup.+5] ions at 30 MeV. The carbon-implanted waveguides were found to be thermally stable after annealing at 450 [degrees]C. A semiempirical formula for predicting the change in the refractive index given the parameters of the implantation process was developed. It is argued that the combination of the basic implantation process with the semiempirical formula can be developed to become a generic method for constructing complex electro-optic circuits with a wave-guided architecture. OCIS codes: 160.2260, 230.7400, 220.4000, 130.3120, 350.4600. %B Applied Optics %I Optical Society of America %V 46 %P 4132-7 %8 2007/// %@ 1559-128X %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edsgao&AN=edsgcl.165971006&site=eds-live %N 19 %! Applied Optics %0 Journal Article %J J. of Non-Cryst. Solids %D 2007 %T

Dielectric Electrooptic Gratings in Potassium Lithium Tantalate Niobate

%A Agranat, A.J. %A de Oliveira, C.E.M. %A Orr, G. %X Volume phase gratings have been fabricated by controlled generation of periodic striations during the growth of copper doped potassium lithium tantalate niobate crystals. Gratings with periods ranging from below 1 to 5 μm were fabricated. It is shown that the fabricated composition grating induces a refractive index grating which is a superposition of a fixed grating and an electrically controlled (electrooptic) grating. The electrooptic grating is produced due to the generation of a spatial modulation of the Curie temperature which is manifested as a correlated modulation of the static dielectric constant. It was also observed that when operated at the immediate vicinity of the phase transition temperature the diffraction efficiency from these gratings was bi-stable at a specific electric field due to an induced shift of the Curie temperature. %B J. of Non-Cryst. Solids %V 353 %P 4405-4410 %G eng %N 47-51 %0 Generic %D 2007 %T Percolation of polar nanoregions: A dynamic approach to the ferroelectric phase transition %A Lerner, S.E. %A Ben Ishai, P. %A Agranat, A.J. %A Feldman, Y. %K calorimetry %K Dielectric properties %K electric modulus %K ferroelectric %K MATERIALS SCIENCE, CERAMICS %K MATERIALS SCIENCE, MULTIDISCIPLINARY %K percolation %K relaxation %X The percolative nature of the ferroelectric phase transition in a potassium tantalate niobate (KTN) crystal is studied using time domain dielectric spectroscopy. A relaxation process linked to the off-center niobium ions is observed. The dynamic nature of this relaxation shows well defined temperature regimes in which it progresses from independent (Arrhenius) to cooperative (Vogel-Fulcher-Tammann) behavior. A recursive fractal model was applied in order to interpret the data obtained from the dielectric measurements. The structural parameters, nu and mu, derived from the correlation functions, enable the investigation of the onset of the phase transition in terms of the fractal dimensions of the polarization excitation. (c) 2007 Elsevier B.V. All rights reserved. %B J. of Non-Cryst. Solids %V 353 %P 4422 - 4427 %8 DEC 1, 2007 %@ 00223093 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000251476300035&site=eds-live %N 47-51 %! JOURNAL OF NON-CRYSTALLINE SOLIDS %0 Journal Article %J Applied Physics Letters %D 2007 %T

Stable electro-optic striation grating produced by programed periodic modulation of the growth temperature.

%A Agranat, Aharon J. %A Kaner, Roy %A Perepelitsa, Galina %A Garcia, Yehudit %K BRAGG gratings %K crystal growth %K DIELECTRICS %K DOUBLE refraction %K electric fields %K REFRACTIVE index %X Electrically controlled Bragg gratings implemented by periodic striations that were produced during the crystal growth are demonstrated in potassium lithium tantalate niobate crystals. The striations were generated by blowing air with periodic flow at the flux surface. The gratings were investigated by measurements of the diffraction efficiency versus the applied electric field. It was found that the composition grating induced correlated gratings of the refractive index and the low frequency dielectric constant. The latter, under the application of a uniform electric field, produced an electrically controlled birefringence grating through the quadratic electro-optic effect. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Applied Physics Letters %V 90 %P 192902 %8 2007/05/07/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=25128106&site=eds-live %N 19 %! Applied Physics LettersApplied Physics Letters %0 Generic %D 2007 %T Separating polarization components through the electro-optic read-out of photorefractive solitons %A Pierangelo, A. %A DelRe, E. %A Ciattoni, A. %A Biagi, G %A Palange, E. %A Agranat, A %K Optics %X

Analyzing the propagation dynamics of a light beam of arbitrary linear input polarization in an electro-activated photorefractive soliton we are able to experimentally find the conditions that separate its linear polarization components, mapping them into spatially distinct regions at the crystal output. Extending experiments to the switching scheme based on two oppositely biased solitons, we are able to transform this spatial separation into a separation of two distinct guided modes. The result is a miniaturized electro-optic polarization separator. (c) 2007 Optical Society of America.

%B Optics Express %V 15 %P 14283 - 14288 %8 OCT 17, 2007 %@ 10944087 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000251223100089&site=eds-live %N 21 %! OPTICS EXPRESS %0 Journal Article %J Physical Review B - Condensed Matter and Materials Physics %D 2006 %T Confinement kinetics in a KTN:Cu crystal: Experiment and theory %A Ben Ishai, P. %A Agranat, A.J. %A Feldman, Y. %B Physical Review B - Condensed Matter and Materials Physics %V 73 %8 2006 / 01 / 01 / %@ 109801211550235X %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-33644787901&site=eds-live %N 10 %! Physical Review B - Condensed Matter and Materials PhysicsPhysical Review B - Condensed Matter and Materials Physics %0 Journal Article %J Optics Letters %D 2006 %T

Electroholographic Tunable Volume Grating in the g44 Configuration

%A Bitman, A. %A Sapiens, N. %A Bartal, G. %A Secundo, L. %A Segev, M. %A Agranat, A.J. %X The g(44) grating is an electroholographic transmission grating in which the applied field is perpendicular to both the grating vector and the wave vector of the incident beam. It is argued that in this configuration the incident beam traverses through a periodically rotating index ellipsoid. It is shown that in the g(44) configuration the Bragg condition is fulfilled for a specific value of the applied field and for a diffracting beam polarization that is perpendicular to that of the incident beam. Consequently, the g(44) grating can be used as an electrically controlled filter. Tunability of 7 nm is demonstrated in a 2mm thick grating. %B Optics Letters %V 31 %P 2849-2851 %G eng %N 19 %0 Journal Article %J Applied Physics Letters %D 2006 %T Pinning-induced round solitons with symmetric nonlinear response for electroactivated optical circuitry. %A Pierangelo, Angelo %A DelRe, E. %A Palange, E. %A Ciattoni, A. %A Garcia, Y. %A Agranat, A.J. %K ANISOTROPY %K CRYSTALLOGRAPHY %K CRYSTALS %K LITHIUM niobate %K Solitons %X

The authors experimentally and theoretically study the formation of transient two-dimensional photorefractive spatial solitons in a striated paraelectric potassium lithium tantalate niobate crystal. The partial pinning to the built-in slablike index structures activates an interplay between the linear and nonlinear responses that leads to round solitons through a highly symmetric anisotropic nonlinearity, the means to self-write compact undistorted optical circuitry. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

%B Applied Physics Letters %I American Institute of Physics %V 89 %P 121123 %8 2006/09/18/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=23073383&site=eds-live %N 12 %! Applied Physics Letters %0 Journal Article %J Applied Physics Letters %D 2006 %T

Submerged waveguide constructed by implantation of 12C ions in electrooptic crystals

%A Ilan, H. %A Gumennik, A. %A Fathei, R. %A Agranat, A.J. %A I. Shachar %A M. Hass %X Waveguide structures were fabricated in potassium lithium tantalate niobate crystals by the implantation of high energy C12 ions. The implantation forms an amorphous layer with a lowered index of refraction within the depth of the crystal, which serves as the cladding of the waveguides. Two amorphous layers were fabricated at 18.8 and 25.6 μm below the surface of the crystal by implantation at 30 and 40 MeV, respectively. This formed a submerged slab waveguide sandwiched between the two amorphous layers and two slab waveguides that were formed between the surface of the crystal and each of the amorphous layers. Coupling between those waveguides was observed and investigated, and confinement of the light in the sandwiched waveguide was demonstrated. © 2006 American Institute of Physics. %B Applied Physics Letters %V 89 %G eng %N 24 %0 Journal Article %J Applied Physics Letters %D 2005 %T Observation of soliton ridge states for the self-imprinting of fiber-slab couplers. %A DelRe, Eugenio %A D'Ercole, Angelo %A Palange, Elia %A Agranat, Aharon J. %K Crystallization %K CRYSTALS %K RADIO frequency %K SEMICONDUCTOR doping %K SOLIDIFICATION %K Solitons %X

We investigate experimentally the energy exchange patterns and consequent propagation dynamics of an extended hybrid-dimensional interaction between a one-dimensional and a two-dimensional spatial soliton in a biased photorefractive crystal. Results show that conditions can be found in which the coupling manifests propagation invariant features. The mechanism hinges on mutual distortion through spatially nonlocal components of response, as opposed to standard wave overlap, which would lead to a diffusion of the needle into the slab mode. These nonlocal-nonlinearity-driven ridge modes represent the instrument for writing fiber-slab couplers, the key to attaining soliton-based wavelength selectivity with electroactivated features. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

%B Applied Physics Letters %V 86 %P 191110 %8 2005/05/09/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=17164784&site=eds-live %N 19 %! Applied Physics LettersApplied Physics Letters %0 Journal Article %J Applied Physics Letters %D 2005 %T

Thermal stability of a slab waveguide implemented by α particles implantation in potassium lithium tantalate niobate.

%A Gumennik, Alexander %A Agranat, Aharon J. %A Shachar, Igal %A Hass, Michael %K ANNEALING of crystals %K CRYSTALS %K LITHIUM tantalate %K PARTICLES (Nuclear physics) %K PHYSICS %K Waveguides %X A slab waveguide was fabricated in a potassium lithium tantalate niobate crystal by the implantation of He2+ ions at 2.26 MeV. The waveguide profile and loss were evaluated by measuring the dark mode TE spectrum using the prism coupling method at λ=1.3 μm. The implantation generated amorphous cladding layer 5 μm below the surface of the crystal with a refractive index lower by 3.9% then that of the substrate. The propagation loss of the waveguided modes was found to be 0.1–0.2 dB/cm. Thermal stability of the waveguide was obtained by isothermal annealing at 351 and 446 °C. Following the annealing the waveguide index profile remained unchanged when subjected to annealing at 150 °C for one week. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) %B Applied Physics Letters %V 87 %P 251917 %8 2005/12/19/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=19316636&site=eds-live %N 25 %! Applied Physics LettersApplied Physics Letters %0 Generic %D 2005 %T Unusual glass-like systems - relaxation dynamics of Cu+ ions in ferroelectric KTN crystals %A Ben Ishai, P. %A de Oliveira, C.E.M. %A Ryabov, Y. %A Agranat, A.J. %A Feldman, Y. %K MATERIALS SCIENCE, CERAMICS %K MATERIALS SCIENCE, MULTIDISCIPLINARY %X We present a broadband dielectric spectroscopy study of potassium tantalate niobate (KTN) crystals, doped with varying amounts of Cu ions. The dielectric landscape in frequency and temperature is rich, with multiple processes in different temperature phases of the crystals. Of particular interest are the processes resulting from Cu and Nb ions in the paraelectric phase of the crystal and from Cu ions in the ferroelectric phase. The linear dependence of the ferroelectric transition temperature in KTN crystals (KTa0.62Nb0.38O3Cu) on the concentration of Nb, as well as the dielectric behavior of the ferroelectric phase transition in these crystals, are well known. We concentrate of the dielectric relaxation resulting from the Cu ions in the crystal lattice. Cu dopants in very small concentrations have been added in the past to enhance the photoreftractive properties of KTN crystals. However the small ionic radius of such dopants, relative to their lattice site, results in virtual dipoles exhibiting dielectric relaxation. The random nature of their distribution throughout the ordered KTN lattice leads to relaxation behavior reminiscent of glass formers. In particular Vogel Fulcher Tammann relaxation of these ions is evident in the paraelectric phase of the crystal. This cooperativity is broken at a critical temperature (T = 354 K) and the relaxation becomes Arrhenius in nature. An explanation in terms of Adam-Gibbs theory is presented where the cooperative cluster is realized by polarized Nb ions linking the widely space Cu ions. At the phase transition (T-c = 295.6 K) this relaxation is 'frozen' by large internal fields caused by the structural shift of the Nb ion in the unit cell. As the temperature drops the Cu ions undergo a reorganization about the multiwell potential leading to a saddle-like process characteristic of liquids in confined systems. An explanation for this behavior is proposed based on free volume concepts, where the relatively small ionic radius of the Cu ions provides the free volume for the relaxing species. The role of the oxygen octahedra as the relaxing species is discussed. (c) 2005 Published by Elsevier BV. %B J. Non-Cryst. Solids %V 351 %P 2786 - 2792 %8 SEP 15, 2005 %@ 00223093 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000231993300033&site=eds-live %N 33-36 %! JOURNAL OF NON-CRYSTALLINE SOLIDS %0 Journal Article %D 2004 %T Fiber-launched ultratight photorefractive solitons integrating fast soliton-based beam manipulation circuitry %A DelRe, Eugenio %A Palange, Elia %A Agranat, Aharon J. %K Electrooptics -- Research %K Photorefractive materials -- Research %K Solitons -- Research %X

The deterministic and reliable singlemode fiber integration with spatial solitons through ultratight needs in photorefractives have been demonstrated. Efficient electro-optic beam handling was allowed where the fiber carried the information sequence and also delivered the photorefractively active control beam that configured the circuitry.

%I American Institute of Physics, Inc. %8 2004/// %@ 0021-8979 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edsgao&AN=edsgcl.123305906&site=eds-live %N 7 %! Journal of Applied Physics %0 Journal Article %J Physical Review B - Condensed Matter and Materials Physics %D 2004 %T Glass-forming liquid kinetics manifested in a KTN: Cu crystal %A Ben Ishai, P. %A de Oliveira, C.E.M. %A Ryabov, Y. %A Feldman, Yu. %A Agranat, A.J. %B Physical Review B - Condensed Matter and Materials Physics %V 70 %P 132104-1-132104-4 %8 2004 / 10 / 01 / %@ 01631829 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselc&AN=edselc.2-52.0-37649030903&site=eds-live %N 13 %! Physical Review B - Condensed Matter and Materials PhysicsPhysical Review B - Condensed Matter and Materials Physics %0 Journal Article %J Applied Physics Letters %D 2004 %T Miniaturization and embedding of soliton-based electro-optically addressable photonic arrays. %A D’Ercole, A. %A Palange, E. %A DelRe, E. %A Ciattoni, A. %A Crosignani, B. %A Agranat, A.J. %K CRYSTALLINE electric field %K CRYSTALS %K electric fields %K ELECTROOPTICS %K LIGHT -- Scattering %K Optics %K PHOTONICS %K REFRACTION (Optics) %X

We achieved the soliton-based miniaturized integration of electro-optic devices in a photorefractive paraelectric bulk crystal, by driving self-trapping through an external bias field in a top-sided electrode geometry. The ensuing spatially resolved electric field manifests a localized voltage-dependent region in which a quasi-uniform field leads to screening-like self-trapped waves at considerably low voltages without sample miniaturization, along with their electro-optic beam manipulation. By replicating the electrode structure, our achievements constitute the basic building block that paves the way to digitally addressable volume photonic manipulator arrays. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

%B Applied Physics Letters %V 85 %P 2679 %8 2004/10/04/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=14713421&site=eds-live %N 14 %! Applied Physics LettersApplied Physics Letters %0 Generic %D 2004 %T

Controlled composition modulation in potassium lithium tantalate niobate crystals grown by off-centered TSSG method

%A de Oliveira, C.E.M. %A Orr, G. %A Axelrold, N. %A Agranat, A.J. %K A2 top seeded solution growth %K B1KLTN %K B1perovskites %K B2dielectric materials %K CRYSTALLOGRAPHY %X Off-centered top-seeded solution growth (TSSG) method is demonstrated as an effective and simple way to generate controlled composition modulation in potassium lithium tantalate niobate (KLTN) single crystals. The changes in concentration were measured by differential interference contrast (DIC) microscopy. Large length with periodic modulations ranging from 1 to 5 mum in period was grown along a KLTN sample with period dispersion lower than 2%. (C) 2004 Elsevier B.V. All rights reserved. %B J. Cryst. Growth %V 273 %P 203 - 206 %8 DEC 17, 2004 %@ 00220248 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000226021000026&site=eds-live %N 1-2 %! JOURNAL OF CRYSTAL GROWTH %0 Generic %D 2004 %T

Resistance degradation due to interstitial hydrogen in photorefractive potassium lithium tantalate niobate single crystals

%A Ivker, M. %A Agranat, A.J. %K Physics, Applied %X Resistance degradation in potassium lithium tantalate niobate (KLTN) doped with iron and titanium was measured in a single sample containing various concentrations of interstitial hydrogen. In this crystal the degradation arose from the migration of interstitial hydrogen and not oxygen vacancies, as reported in previous research. Interstitial hydrogen and oxygen vacancy defects both arise to compensate the valence shortfall of the substitutional iron impurities and the thermodynamic balance between the two compensation mechanisms can be controlled using reaction chemistry techniques. Through appropriate annealing treatments a single crystal of KLTN was prepared in three states: hydrogen-rich oxidized, hydrogen-poor reduced, and hydrogen-rich reduced. The characteristic degradation times for the three cases were 29, 2710, and 26 min, respectively. The degradation rate is correlated with hydrogen concentration and not oxidation state of the crystal. Infrared absorption from near the two electrodes of the hydrogen-rich reduced crystal after degradation confirmed polarization of the hydrogen concentration. Electrocoloration was also found to correlate with hydrogen-it was observed in both hydrogen-rich states, but was absent from the hydrogen-poor crystal. (C) 2004 American Institute of Physics. %B J. Applied Physics %V 96 %P 6405 - 6408 %8 DEC 1, 2004 %@ 00218979 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000225300800071&site=eds-live %N 11 %! JOURNAL OF APPLIED PHYSICS %0 Generic %D 2003 %T Emergence of linear wave segments and predictable traits in saturated nonlinear media %A DelRe, E. %A D'Ercole, A. %A Agranat, A.J. %K Optics %X

We find the key behind the existence traits of asymptotic saturated nonlinear optical solitons in the emergence of linear wave segments. These traits, produced by the progressive relegation of nonlinear dynamics to wave tails, allow a direct and versatile analytical prediction of self-trapping existence conditions and simple soliton scaling laws, which we confirm experimentally in saturated-Kerr self-trapping observed in photorefractives. This approach provides the means to correctly evaluate beam tails in the saturated regime, which is instrumental in the prediction of soliton interaction forces. (C) 2003 Optical Society of America.

%B Optiocs Letters %V 28 %P 260 - 262 %8 FEB 15, 2003 %@ 01469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000180757400014&site=eds-live %N 4 %! OPTICS LETTERS %0 Generic %D 2002 %T Dielectric nonlinearity in photorefractive spatial soliton formation %A DelRe, E. %A Agranat, A.J. %K Optics %K PHYSICS, ATOMIC, MOLECULAR & CHEMICAL %X

We find that the anomalous behavior of optical spatial screening solitons observed in the high-symmetry paraelectric phase is a consequence of nonlinear dielectric effects. These, coupled to space charge in saturated conditions, change the effective optical nonlinearity even far from the phase-transition regime.

%B Physics Review A %V 65 %8 MAY, 2002 %@ 10502947 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000175744300057&site=eds-live %N 5 %! PHYSICAL REVIEW A %0 Generic %D 2002 %T Electro-optic beam manipulation through photorefractive needles %A DelRe, E. %A Crosignani, B. %A Di Porto, P %A Palange, E. %A Agranat, A.J. %K Optics %X

We demonstrate electro-optic spatial two-dimensional mode switching in a bulk sample of potassium lithium tantalate niobate. Spatial confinement, mode coupling, and electro-optic functionality are mediated by two photorefractive needle solitons of opposite electroholographic charges embedded together in their anisotropic lobular structure. (C) 2002 Optical Society of America.

%B Optics Letters %V 27 %P 2188 - 2190 %8 DEC 15, 2002 %@ 01469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000179795000014&site=eds-live %N 24 %! OPTICS LETTERS %0 Journal Article %J Topics in Applied Physics %D 2002 %T

Optical lambda-switching at telecom wavelengths based on electroholography 

%A Agranat, A.J. %X Electroholography is a wavelength-selective optical switching method based on governing of the reconstruction process of volume holograms by means of an electric field. Electroholography is based on the voltage-controlled photorefractive effect in the paraelectric phase. The basic switching device is an electrically controlled Bragg grating or a volume hologram stored in a volume of a paraelectric crystal by the photorefractive process. The basic electroholographic switching operation is the reconstruction of a volume grating (hologram), which requires that the Bragg condition be satisfied, and therefore is wavelength selective. In addition the applied field governs the efficiency of the reconstruction. Consequently, electroholographic switching includes grouping, multicasting, power management and non-intrusive data as an integral part of the switching operation. In preliminary measurements the performance envelope of the electroholography-based switch, is a cube of 1.8 mm3 was found to be as follows: The minimum net insertion loss is 0.5 dB per switching operation. The minimum loss when a beam propagates through a latent grating is 0.2%. The Polarization-Dependent Loss (PDL) in a device that includes diversity architecture is less than 0.4 dB and the Polarization Mode Dispersion (PMD) is less than 0.07 ps. Bit-error rate (BER) in a switch operating at 40 Gb/s was measured to be 10-13. These features make electroholography ideal for circuit switching applications. Finally, response times of approximately 10 ns were measured, opening the way to burst switching applications. %B Topics in Applied Physics %V 89 %P 129-156 %G eng %0 Journal Article %J Optical Materials %D 2002 %T

Phase transitions, related properties and possible applications of (K,Li)(Ta,Nb)O3 crystals

%A Trepakov, Vladimir A. %A Jastrabik, Lubomir %A Kapphan, Siegmar %A Giulotto, Enrico %A Agranat, Aharon J. %X It is shown that doping the highly polarizable KTaO3 perovskite simultaneously by Li and Nb (K1−xLixTa1−yNbyO3, KLTN) gives rise to new impressive dipole ordering effects, very unusual physical properties and strong responses with respect to doping parameters. Besides, KLTN has outstanding perspectives of application in electrically controlled holographic and compositionally graded pyroelectric devices. %B Optical Materials %I Elsevier B.V. %V 19 %P 13 - 21 %8 2002/1/1/2002/// %@ 0925-3467 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselp&AN=S0925346701001963&site=eds-live %N Photonic Materials for the 21st Century. Proceedings of the 2nd International Symposium on Laser, Scintillator and Nonlinear Opt %! Optical MaterialsOptical Materials %0 Generic %D 2002 %T

Relaxation processes of off-center impurities in KTN : Li crystals

%A Bitton, G. %A Feldman, Y. %A Agranat, A.J. %K MATERIALS SCIENCE, CERAMICS %K MATERIALS SCIENCE, MULTIDISCIPLINARY %X The dielectric and ferroelectric properties of K1-xLixTa1-yNbyO3 (KLTN) crystals as functions of temperature, frequency, and electric field are presented. Measurement of the polarization as a function of temperature indicates the existence of polarized microregions at temperatures well above the phase transition (PT) temperature. In the vicinity of the PT those microregions respond cooperatively and contribute to the observed macroscopic polarization. This cooperative behavior was also evident from dielectric relaxation measurements. Two relaxation processes were observed, one at high frequency and the other at low frequency. In both processes the relaxation time and the relaxation step (DeltaE) were found to increase as the PT temperature was approached. Those processes originate from movement of off-center ions in a multi-well potential. In the vicinity of the PT the correlation length of the host lattice is increased and the movements of the off-center ions become more and more correlated. The increased number of cooperatively relaxing ions increases the relaxation time and the relaxation amplitude. (C) 2002 Published by Elsevier Science B.V. %B J. Non-Cryst. Solids %V 305 %P 362 - 367 %8 JUL 1, 2002 %@ 00223093 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000176261600048&site=eds-live %N 1-3 %! JOURNAL OF NON-CRYSTALLINE SOLIDS %0 Generic %D 2001 %T Anisotropic charge displacement supporting isolated photorefractive optical needles %A DelRe, E. %A Ciattoni, A. %A Agranat, A.J. %K Optics %X

Strong asymmetry in the charge distribution supporting a single noninteracting spatial needle soliton in a paraelectric photorefractive is directly observed by means of electroholographic readout. Whereas in trapping conditions a quasi-circular wave is supported, the underlying double-dipolar structure can be made to support two distinct propagation modes. (C) 2001 Optical Society of America

%B Optics Letters %V 26 %P 908 - 910 %8 JUN 15, 2001 %@ 01469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000169185900016&site=eds-live %N 12 %! OPTICS LETTERS %0 Journal Article %J Optical Materials %D 2001 %T

Wavelength-selective photonic switching in paraelectric potassium lithium tantalate niobate

%A Agranat, Aharon J. %A Secundo, Lavi %A Golshani, Noam %A Razvag, Meir %X A generic wavelength-selective switching method is presented. The method is based on the voltage-controlled photorefractive effect in paraelectric crystals. The switch consists of a crystal at the paraelectric phase in which a space charge grating was stored by a photorefractive process. Diffraction occurs by the application of a uniform electric field that causes the space charge grating to induce an index grating. Results of the diffraction efficiency as a function of the applied field and the time dependence of the diffracted beam are presented. The performance envelop of a switch based on this effect is briefly discussed. %B Optical Materials %I Elsevier B.V. %V 18 %P 195 - 197 %8 2001/1/1/2001/// %@ 0925-3467 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselp&AN=S0925346701001665&site=eds-live %N 1 %! Optical MaterialsOptical Materials %0 Generic %D 2000 %T Collisions and inhomogeneous forces between solitons of different dimensionality %A DelRe, E. %A Trillo, S. %A Agranat, A.J. %K Optics %X

We exploit nonlinear propagation in photorefractive crystals to observe the phenomenology associated with the collision and interaction of solitons of different tranverse dimensions: a self-trapped stripe and a round soliton. Along with evidence of particlelike behavior, our results indicate the emergence of a new phenomenology related to the hybrid-dimensional system. (C) 2000 Optical Society of America. OCIS codes: 190.5530, 190.5330.

%B Optics Letters %V 25 %P 560 - 562 %8 APR 15, 2000 %@ 01469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000086501800016&site=eds-live %N 8 %! OPTICS LETTERS %0 Generic %D 2000 %T

A photo-oxidation mechanism for patterning and hologram formation in conjugated polymer/glass composites

%A Levi, O. %A Perepelitsa, G. %A Davidov, D. %A Shalom, S. %A Benjamin, I. %A Neumann, R. %A Agranat, A.J. %A Avny, Y. %K Physics, Applied %X Improved diffraction efficiency was observed in holograms stored in disordered conjugated polymer/glass composites. The conjugated polymers used were alkoxy substituted poly(phenylenevinylne) analogs and the glass matrices were zirconia-organosilica xerogels. Investigation of the mechanism of hologram formation revealed evidence of a photochromic process consisting of light induced photo-oxidation (bleaching) of the embedded conjugated polymer resulting in the formation of an absorption grating and a phase grating. Investigation of the hologram formation revealed that the process was oxygen dependent. Oxygen removal increases hologram formation time by more than an order of magnitude and halves the total hologram efficiency. The oxygen dependence was also highly correlated with photobleaching of the samples and beam interaction of the writing beams. The chemical transformations upon photobleaching were shown by infrared and Raman spectroscopy to involve chain scission and oxidation of the polymer at the vinylic position of the conjugated polymer. Film preparation of the composites was optimized showing a tenfold improvement in the holographic properties compared to our previous results. The optimized treatment method allows for a high, > 20%, diffraction efficiency, eta, to be obtained for the 2.5-mu m-thick polymer/glass films. Light sensitivity was compared for several polymer/glass composites and was correlated to the absorption curves and holographic diffraction efficiency showing that the new composites and film preparation techniques are promising for holographic materials sensitive in the blue and ultraviolet spectral regions. A method of information fixing by preventing oxygen entry to the composite film resulted in a fourfold increase of the erasure time. These findings suggest that holograms can be fixed for a long term by nonoxygen permeable coating, applied after hologram formation. (C) 2000 American Institute of Physics. [S0021- 8979(00)07114-0]. %B J. of Appl. Physics %V 88 %P 1236 - 1243 %8 AUG 1, 2000 %@ 00218979 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000088166500006&site=eds-live %N 3 %! JOURNAL OF APPLIED PHYSICS %0 Journal Article %J Ferroelectrics %D 2000 %T

Dielectric properties of K 1−x , Li x , Ta l−y , Nby 03 crystals.

%A Bitton, Gabby %A Feldman, Yuri %A Agranat, Aharon J. %B Ferroelectrics %V 239 %P 213-224 %8 2000/02/02/ %@ 00150193 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=75873623&site=eds-live %N 1 %! FerroelectricsFerroelectrics %0 Journal Article %J Atomic Spectroscopy %D 2000 %T

Direct ICP-OES Determination of Cu, Fe, Li, Ti and V in Potassium Lithium Tantalate Niobate Crystals

%A I. Segal %A E. Dorfman %A O. Yoffe %A I. Bezrukavnikov %A Agranat, A.J. %B Atomic Spectroscopy %V 21 %P 46-49 %G eng %N 2 %0 Journal Article %J Applied Optics %D 2000 %T

Free Space Optical Cross-Connect Switch by Use of Electroholography

%A B. Pessach %A Bartal, G. %A Refaeli, E. %A Agranat, A.J. %X An electrically controlled holographic switch is proposed as a building block for a free-space optical interconnection network. The switch is based on the voltage-controlled photorefractive effect in KLTN crystals at the paraelectric phase. It is built of electrically controlled Bragg gratings stored in the volume of the crystal. A compact switch that connects four high-speed fiber-optic communication channels with high efficiency is demonstrated experimentally. The switch performance is investigated and optimized. This switch is extremely attractive for cascaded switching arrays such as those found in multistage interconnect networks. %B Applied Optics %V 39 %P 746-758 %G eng %N 5 %0 Generic %D 2000 %T Soliton electro-optic effects in paraelectrics %A DelRe, E. %A Tamburrini, M. %A Agranat, A.J. %K Optics %X

The combination of charge separation induced by the formation of a single photorefractive screening soliton and an applied external bias field in a paraelectric is shown to lead to a family of useful electro-optic guiding patterns and properties. (C) 2000 Optical Society of America.

%B Optics Letters %V 25 %P 963 - 965 %8 JUL 1, 2000 %@ 01469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000087944400009&site=eds-live %N 13 %! OPTICS LETTERS %0 Generic %D 2000 %T Stable oscillating nonlinear beams in square-wave-biased photorefractives %A Tosi-Beleffi, G.M. %A Presi, M. %A DelRe, E. %A Boschi, D. %A Palma, C. %A Agranat, A.J. %K Optics %X

We demonstrate experimentally that, in a paraelectric, nonstationary boundary conditions can dynamically halt the intrinsic instability of quasi-steady-state photorefractive self-trapping, driving beam evolution into a stable oscillating two-soliton-state configuration. (C) 2000 Optical Society of America OCIS codes: 190.5330, 230.3090.

%B Optics Letters %V 25 %P 1538 - 1540 %8 OCT 15, 2000 %@ 01469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000089834900016&site=eds-live %N 20 %! OPTICS LETTERS %0 Journal Article %J Ferroelectric Letters %D 1999 %T

The Bulk Photovoltaic effect in Photorefractive KLTN Crystals

%A Bitton, G. %A Agranat, A.J. %A Fridkin, V. M. %X Experimental evidence of the bulk photovoltaic effect in photorefractive K1-xLixTa1-xNbyO3 (KLTN) crystals is shown. The dependence of the bulk photovoltaic effect on the pbotorefractive impurities type is presented. The current voltage characteristic is presented for different temperatures. It was found that, in Fe-doped KLTN crystals at low temperature, the bulk photovoltaic effect is the dominant transport mechanism contributing to the photorefractive process. %B Ferroelectric Letters %V 25 %P 1-9 %G eng %N 1-2 %0 Journal Article %J Synthetic Metals %D 1999 %T

Conjugated polymeric composites for holographic storage

%A Levi, O. %A Shalom, S. %A Benjamin, I. %A Perepelitsa, G. %A Agranat, A.J. %A Neumann, R. %A Avny, Y. %A Davidov, D. %X We report here on the fabrication and optimization of composites of conjugated polymer in Sol-Gel and PVA matrices. FTIR spectroscopy as well as other observations show that efficient phase and absorption holograms can be created in the material upon illumination, via the photochromic effect. The main contribution to the absorption change is chain scission and photo-oxidation mechanism. Optimized holographic composites with diffraction efficiencies as high as 26% are shown. Beam interaction between the writing beams is observed for these composites, while the diffraction efficiencies was improved by an order of magnitude. %B Synthetic Metals %V 102 %P 1178-1181 %G eng %0 Generic %D 1999 %T Nonlinear optical diffraction effects and solitons due to anisotropic charge-diffusion-based self-interaction %A Crosignani, B. %A Degasperis, A %A DelRe, E. %A Di Porto, P %A Agranat, A.J. %K PHYSICS, MULTIDISCIPLINARY %X

We report the first observation of self-modified optical diffraction, beam ellipticity recovery and conservation, and intensity independent self-focusing in an anisotropic diffusion-type nonlinearity realized in ferroelectrics heated above the centrosymmetric transition. The interaction, a photorefractive diffusion-driven quadratic nonlinearity, constitutes the first known natural realization of a higher-order logarithmic nonlinearity and allows an analytical description of the observed phenomena and the prediction of a class of noncircular solitons with no characteristic length scale.

%B Physics Review %V 82 %P 1664 - 1667 %8 FEB 22, 1999 %@ 00319007 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000078715100014&site=eds-live %N 8 %! PHYSICAL REVIEW LETTERS %0 Generic %D 1999 %T Spontaneous self-trapping of optical beams in metastable paraelectric crystals %A DelRe, E. %A Tamburrini, M. %A Segev, M. %A Della Pergola, R %A Agranat, A.J. %K PHYSICS, MULTIDISCIPLINARY %X

We report on the observation of a new mechanism for self-trapping of optical beams: self-trapping that stems from spontaneous creation of ferroelectric crystalline clusters, seeded by a weak photorefractive diffusion field. This is an evident observation of the highly nonlinear aspects of propagation in a thermodynamically metastable system, including optically driven crystalline ordering in a medium undergoing a phase transition.

%B Physics Review Letters %V 83 %P 1954 - 1957 %8 SEP 6, 1999 %@ 00319007 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000082392800014&site=eds-live %N 10 %! PHYSICAL REVIEW LETTERS %0 Journal Article %J Phys. Rev. B Rapid Comm. %D 1998 %T

Holographic Storage in Conjugated Polymers Composites

%A Levi, O. %A Perepelitsa, G. %A Davidov, D. %A Agranat, A.J. %A Benjamin, I. %A Shalom, S. %A Neumann, R. %A Avny, Y. %X We report here on the fabrication and optimization of composites of conjugated polymer in Sol-Gel and PVA matrices. FTIR spectroscopy as well as other observations show that efficient phase and absorption holograms can be created in the material upon illumination, via the photochromic effect. The main contribution to the absorption change is chain scission and photo-oxidation mechanism. Optimized holographic composites with diffraction efficiencies as high as 26% are shown. Beam interaction between the writing beams is observed for these composites, while the diffraction efficiencies was improved by an order of magnitude. %B Phys. Rev. B Rapid Comm. %V 57 %P 12647-12650 %G eng %0 Generic %D 1998 %T One-dimensional steady-state photorefractive spatial solitons in centrosymmetric paraelectric potassium lithium tantalate niobate %A DelRe, E. %A Crosignani, B. %A Tamburrini, M. %A Segev, M. %A Mitchell, M. %A Refaeli, E. %A Agranat, A.J. %K Optics %X

We report the first observation of spatial one-dimensional photorefractive screening solitons in centrosymmetric media and compare the experimental results with recent theoretical predictions. We find good qualitative agreement with theory. (C) 1998 Optical Society of America.

%B Optics Letters %V 23 %P 421 - 423 %8 MAR 15, 1998 %@ 01469592 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=000072700700007&site=eds-live %N 6 %! OPTICS LETTERS %0 Journal Article %J Applied Optics %D 1998 %T

Electric field multiplexing of volume hologram in paraelectric crystals

%A Balberg, M. %A Razvag, M. %A Refaeli, E. %A Agranat, A.J. %X Electric-field multiplexing (EFM) results from the tuning of the effective wavelength of the light beam inside a photorefractive crystal. This tuning results from the application of an external electric field to the crystal during holographic recording. We demonstrate the high Bragg selectivity of this multiplexing technique in paraelectric crystals and compare it with the selectivity obtained in the ferroelectric phase. The effects of the two major physical parameters of working in the paraelectric phase, the temperature and the external electric field applied during the writing stage, are investigated. Experimental results of the EFM of three image-bearing holograms recorded in reflection geometry are presented along with a qualitative analysis of the Bragg selectivity in paraelectric crystals. %B Applied Optics %V 37 %P 841-847 %G eng %0 Journal Article %J Phys. Rev. B %D 1998 %T

Formation of Metastable Ferroelectric Clusters in K1-XLiXTa1-YNbYO3:Cu, V at the Paraelectric Phase

%A Bitton, G. %A Razvag, M. %A Agranat, Aharon J. %B Phys. Rev. B %V 58 %P 5282-5286 %G eng %N 9 %0 Journal Article %J Optics Letters %D 1998 %T

Investigation of the holographic storage capacity of paraelectric KLTN

%A B. Pessach %A Refaeli, Eli %A Agranat, Aharon J. %B Optics Letters %V 23 %P 642-644 %G eng %N 4/15 %0 Journal Article %J Applied Physics Letters %D 1998 %T Two-dimensional photorefractive spatial solitons in centrosymmetric paraelectric potassium–lithium–tantalate–niobate. %A DelRe, Eugenio %A Tamburrini, Mario %A Segev, Mordechai %A Refaeli, Eli %A Agranat, Aharon J. %K ION traps %K PHOTOREFRACTIVE materials %K Solitons %X

We report the observation of steady-state two-dimensional photorefractive self-trapping and screening spatial soliton formation in a sample of potassium–lithium–tantalate–niobate in the centrosymmetric paraelectric phase. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]Copyright of Applied Physics Letters is the property of American Institute of Physics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

%B Applied Physics Letters %V 73 %8 1998/07/06/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=4871958&site=eds-live %N 1 %! Applied Physics LettersApplied Physics Letters %0 Journal Article %J Applied Physics Letters %D 1997 %T Copper, hydrogen, and titanium incorporation in potassium lithium tantalate niobate single crystals. %A Xiaolin Tong %A Min Zhang %A Yariv, Amnon %A Agranat, Aharon J. %K CRYSTALS %K DIFFUSION %K HYDROGEN ions %X Analyzes the model proposed for the diffusion of copper, hydrogen and titanium through potassium lithium tantalate niobate crystals. Occupation of potassium/lithium vacant sites by copper and hydrogen ions; Effect of titanium on the ability of hydrogen ions to stay at the sites; Reduction in the hydrogen ion concentration. %B Applied Physics Letters %V 70 %P 1688 %8 1997/03/31/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=4319805&site=eds-live %N 13 %! Applied Physics LettersApplied Physics Letters %0 Journal Article %J Applied Physics Letters %D 1997 %T Ferroelectric domain gratings and Barkhausen spikes in potassium lithium tantalate niobate. %A Xiaolin Tong %A Yariv, Amnon %A Min Zhang %A Agranat, Aharon J. %A Hofmeister, Rudolf %A Leyva, Victor %K BARKHAUSEN effect %K CRYSTALS %K HOLOGRAPHY %K NIOBATES %X Examines the formation of Barkhausen spikes in volume phase holograms of potassium lithium tantalate niobate crystals. Effect of ferroelectric domain reversal induced by photorefractive space charge fields; Measurement of displacement currents; Changes in diffraction efficiency during a single macrodomain switching. %B Applied Physics Letters %V 70 %P 2241 %8 1997/04/28/ %@ 00036951 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edb&AN=4289619&site=eds-live %N 17 %! Applied Physics LettersApplied Physics Letters %0 Generic %D 1997 %T

Dipolar holographic gratings induced by the photorefractive process in potassium lithium tantalate niobate at the paraelectric phase

%A Agranat, A.J. %A Razvag, M. %A Balberg, M. %A Leyva, V %K Optics %X We present experimental evidence indicating the formation of dipolar holographic gratings in potassium lithium tantalate niobate at the paraelectric phase slightly above the phase transition, These gratings are formed in the dark, following the writing of space-charge-based photorefractive gratings, under an external electric field. The dipolar gratings create a spatial modulation of the low-frequency dielectric constant, and the latter induces a spatially correlated modulation of the polarization, which is transformed into birefringence gratings through the quadratic electro-optic effect. (C) 1997 Optical Society of America. %B J. Opt. Soc. Am. B %V 14 %P 2043 - 2048 %8 AUG, 1997 %@ 07403224 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=A1997XP66100016&site=eds-live %N 8 %! JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS %0 Journal Article %J Phys. Rev. B %D 1997 %T

Holographic Gratings by Spacial Modulation of the Curie-Weiss Temperature in Photorefractive K1-XLiXTa1-YNbYO3:Cu,V

%A Agranat, A.J. %A Razvag, M. %A Balberg, M. %A Bitton, G. %B Phys. Rev. B %V 55 %P 12818-12821 %G eng %N 19 %0 Journal Article %J Optics Letters %D 1997 %T

Spatial solitons in centrosymmetric photorefractive media

%A Segev, M. %A Agranat, A.J. %X We predict spatial solitons in photorefractive centrosymmetric media driven by the dc Kerr effect. %B Optics Letters %V 22 %P 1299-1301 %G eng %N 17 %0 Generic %D 1996 %T

The charge controlled analog synapse

%A Agranat, A.J. %A Schwartzglass, O. %A Shappir, J. %K ENGINEERING, ELECTRICAL & ELECTRONIC %K Physics, Applied %K PHYSICS, CONDENSED MATTER %X A generic circuit, the charge controlled analog synapse (CCAS) is presented. The CCAS is designed to be the basic building block in microelectronic realizations of large scale artificial neural networks. It is based on representing the synaptic strength as a charge packet which controls the junction capacitance of a reverse biased diode. The CCAS is a synapse with three main features: (i) a small cell with few components per cell; (ii) a short term dynamic memory, and (iii) a variable accuracy which depends on the cell size. The principle of operation of the CCAS is explained. Details of the design of a first prototype are given. Experimental results which substantiate the theoretical predictions are presented. Finally, the basic properties of the CCAS are discussed. Copyright (C) 1996 Elsevier Science Ltd %B Solid State Electronics %V 39 %P 1435 - 1439 %8 OCT, 1996 %@ 00381101 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edswsc&AN=A1996VJ86600004&site=eds-live %N 10 %! SOLID-STATE ELECTRONICS %0 Journal Article %J Neurocomputing %D 1996 %T

Letter: VLSI implementation of pulsating neural networks

%A Schwartzglass, Offer %A Agranat, Aharon J. %X We describe a generic approach for realizing networks of pulsating neurons based on charge pumping of interface states situated in the channel of MOS transistors. Two basic building blocks will be described: the pulse activated charge pumping (PSCP) synapse, and the charge sensitive oscillator (CSO). The PSCP synapse which operates as either a short or a long term memory device which produces a charge packet proportional to the number of pulses applied to its input, will be described in detail together with experimental results demonstrating its capability. The CSO circuit which is a charge controlled oscillator will be described together with simulations of its output frequency dependence on its input voltage, and the relation between the temporal dependence of output waveform on its input charge. %B Neurocomputing %I Elsevier B.V. %V 10 %P 405 - 413 %8 1996/1/1/1996/// %@ 0925-2312 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselp&AN=0925231296001385&site=eds-live %N Financial Applications %! NeurocomputingNeurocomputing %0 Journal Article %J Optics Letters %D 1996 %T

Electroholographic neurons implemented on potassium lithium tantalate niobate crystals

%A Balberg, M. %A Razvag, M. %A Vidro, S. %A Refaeli, E. %A Agranat, A.J. %X We describe a new approach for constructing large-scale artificial neural networks. The novelty of our approach is based on the concept of electroholography (EH), which permits interconnecting of electronic neurons by minute-volume holograms, using the voltage-controlled photorefractive effect in paraelectric crystals. Crystals of potassium lithium tantalate niobate (KLTN) in the paraelectric phase are shown to be suitable for implementing this concept. A small network composed of two KLTN crystals on which holographic connections are recorded is presented to demonstrate the EH approach. %B Optics Letters %V 21 %P 1435-1439 %G eng %N 19 %0 Journal Article %J Applied Physics Letters %D 1996 %T

Photorefractive hologram fixing by a 4K cooldown to the phase transition in KLTN

%A Agranat, A.J. %A Razvag, M. %A Balberg, M. %B Applied Physics Letters %V 68 %P 2469-2471 %G eng %0 Journal Article %J Physica A: Statistical Mechanics and its Applications %D 1993 %T

Electro-holographic artificial neural networks

%A Agranat, Aharon J. %X A new approach for implementing artificial neural networks (ANNs), based ona novel concept in volume holographic storage-electroholography (EH)-is described. EH is based on the use of paraelectric photorefractive crystals in which the photorefractive mechanism is created in the paraelectric phase. Thus the quadratic electrooptic effect is used to transform the information carrying space charge fields into birefringence gratings, and therefore the diffraction efficiency is governed by an external electric field. This principle enables the construction of a page oriented architecture in which each neuron is implemented as a local electronic circuit, governing the diffraction efficiency of a small volume hologram representing the axon of the neuron. The EH approach is expected to enable the construction of networks with 105−106 neurons, each with 103−104 synapses. %B Physica A: Statistical Mechanics and its Applications %I Elsevier B.V. %V 200 %P 608 - 612 %8 1993/1/1/1993/// %@ 0378-4371 %G eng %U http://search.ebscohost.com/login.aspx?direct=true&db=edselp&AN=037843719390566M&site=eds-live %! Physica A: Statistical Mechanics and its ApplicationsPhysica A: Statistical Mechanics and its Applications %0 Journal Article %J Electronics Letters %D 1993 %T

The Pulse Stimulated Charge Pumping Synapse

%A Schwartzglass, O. %A Shappir, J. %A Agranat, Aharon J. %B Electronics Letters %V 29 %P 1433-1435 %G eng