Marcus, G. & Tsori, Y. Phase Separation Transition in Liquids and Polymers Induced by Electric Field Gradients. Journal of the Physical Society of Japan 78, (2009). Publisher's VersionAbstract
Spatially uniform electric fields have been used to induce instabilities in liquids and polymers, and to orient and deform ordered phases of block-copolymers. Here we discuss the demixing phase transition occurring in liquid mixtures when they are subject to spatially nonuniform fields. Above the critical value of potential, a phase-separation transition occurs, and two coexisting phases appear separated by a sharp interface. Analytical and numerical composition profiles are given, and the interface location as a function of charge or voltage is found. The possible influence of demixing on the stability of suspensions and on inter-colloid interaction is discussed. ©2009 The Physical Society of Japan
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Shwa, D., Eisenmann, S., Marcus, G. & Zigler, A. Using the self-filtering property of a femtosecond filament to improve second harmonic generation. Optics Express 17, 8, 6451 - 6456 (2009). Publisher's VersionAbstract
In this paper we demonstrate the use of NIR femtosecond filament for improving the generation of second harmonic using a type I BBO crystal. Using this method the beam propagation factor (M2) of the second harmonic was improved significantly; which led to enhancement of the attainable SH intensity by up to two orders of magnitude. This method can be beneficial for applications demanding high intensities, small spot size or long interaction lengths.
Marcus, G., Samin, S. & Tsori, Y. Phase-separation transition in liquid mixtures near curved charged objects. Journal of Chemical Physics 129, 6, 061101 - 4 (2008). Publisher's VersionAbstract
We study the thermodynamic behavior of nonpolar liquid mixtures in the vicinity of curved charged objects, such as electrodes or charged colloids. There is a critical value of charge (or potential), above which a phase-separation transition occurs, and the interface between high- and low-dielectric constant components becomes sharp. Analytical and numerical composition profiles are given, and the equilibrium front location as a function of charge or voltage is found. We further employ a simple Cahn–Hilliard type equation to study the dynamics of phase separation in spatially nonuniform electric fields. We find an exponential temporal relaxation of the demixing front location. We give the dependence of the steady-state location and characteristic time on the charge, mixture composition and ambient temperature. [ABSTRACT FROM AUTHOR]
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Marcus, G., Pearl, S. & Pasmanik, G. Stimulated Brillouin scattering pulse compression to 175 ps in a fused quartz at 1064 nm. Journal of Applied Physics 103, 10, 103105 - 4 (2008). Publisher's VersionAbstract
Stimulated Brillouin scattering pulse compression of a 2.5 ns laser into a 175 ps pulse using a fused quartz is demonstrated without optical damage. The synchronization and the time jitter between the initial and the compressed pulses were measured (σ<80 ps) and analyzed numerically. [ABSTRACT FROM AUTHOR]
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Marcus, G., Louzon, E., Henis, Z., Maman, S. & Mandelbaum, P. Analysis of the x-ray spectrum emitted by laser-produced plasma of dysprosium. Journal of the Optical Society of America B 24, 5, 1187 - 1192 (2007). Publisher's Version
Marcus, G., Zigler, A. & Friedland, L. Molecular vibrational ladder climbing using a sub-nanosecond chirped laser pulse. Europhysics Letters 74, 1, 43 - 48 (2006). Publisher's Version Full text.pdf
Goren, C., Tzuk, Y., Marcus, G. & Pearl, S. Amplified Spontaneous Emission in Slab Amplifiers. Quantum Electronics, IEEE Journal of 42, 12, 1239 - 1247 (2006).Abstract
Amplified spontaneous emission (ASE) occurs in media with large gain, and affects both the magnitude and the spatial distribution of the inversion. In this work we theoretically study the effect of ASE in three-dimensional, rectangular slab amplifiers, using Monte Carlo type computer simulations. We found that in one-dimensional amplifiers ASE is always larger at the edges so that the inversion has a maxima at the center of the amplifier. However, in two- and three-dimensional amplifiers, the inversion has a minimum at the center of the amplifier for low gain, and a maximum at the center of the amplifier for high gain. Thus, the inversion profile can be changed by increasing the gain from a minimum at the center, through a plateau, to a maximum at the center. A simple analytical theory was developed and agrees with these results
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Marcus, G., Friedland, L. & Zigler, A. Autoresonant excitation and control of molecular degrees of freedom in three dimensions. Physical Review A 72, 3, (2005). Publisher's VersionAbstract
A classical, three-dimensional analysis of excitation and control of vibrational-rotational degrees of freedom of a polar diatomic molecule by chirped laser field is presented. The control strategy is based on autoresonance (adiabatic nonlinear synchronization) phenomenon, in which the molecule automatically adjusts its state for staying in a persistent resonance with the laser field despite variation of the laser frequency. Thresholds on driving field amplitudes for entering the autoresonant excitation regime by passage through different resonances are calculated. In autoresonance, the molecule can be excited to large energies and approach the dissociation limit by substantially weaker laser fields than with constant-frequency drives.
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Marcus, G., Zigler, A., Eger, D., Bruner, A. & Englander, A. Generation of a high-energy ultrawideband chirped source in periodically poled LiTaO3. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 22, 3, 620 - 622 (2005).Abstract
A method for generation of a chirped, ultrawideband infrared source by use of optical parametric generation in periodically poled crystals and pumped by a chirped Ti:sapphire laser is described. A similar to35% bandwidth in the idler branch was demonstrated in a periodically poled LiTaO3 crystal pumped by a chirped Ti:sapphire laser with 2.1% bandwidth. Optical parametric generation and optical parametric amplification configuration allowed us to generate up to a similar to250-muJ chirped pulse from 2.1 to 3 mum. (C) 2005 Optical Society of America.
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Marcus, G., Friedland, L. & Zigler, A. From quantum ladder climbing to classical autoresonance. Physical Review A 69, 1, (2004). Publisher's VersionAbstract
The autoresonance phenomenon allows excitation of a classical, oscillatory nonlinear system to high energies by using a weak, chirped frequency forcing. Ladder climbing is its counterpart in quantum mechanics. Here, for the first time to our knowledge, conditions for the transition from the quantum to the classical regimes are outlined. The similarities and differences between the two approaches are presented.
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Levin, M., Marcus, G., Pukhov, A., Zigler, A. & Sasorov, P. High-current capillary discharge with prepulse ablative plasma. Journal of Applied Physics 93, 2, (2003). Publisher's VersionAbstract
Generation of axisymmetric stable, long plasma channels with temperatures of 8 eV and electron densities ∼ 10[sup 19] cm[sup -3] by a high-current evaporating-wall capillary discharge with prepulse ablative plasma is reported. Results of spectroscopic measurements of the temperature and electron density of plasma produced in a polyethylene capillary are presented. The discharge provides a convenient source of dense highly ionized plasmas for laser-plasma interaction studies. [ABSTRACT FROM AUTHOR]
Marcus, G., Zigler, A., Englander, A., Katz, M. & Ehrlich, Y. Generation of ultrawide-band chirped sources in the infrared through parametric interactions in periodically poled crystals. Applied Physics Letters 82, 2, 164 - 166 (2003). Publisher's VersionAbstract
A method to generate chirped ultrawide-band sources with a chirp bandwidth of about 50% in the infrared is described and experimentally verified. It is based on optical parametric generation in periodically poled crystals with a chirped Ti:sapphire as a pump source. We have demonstrated a 27% wide bandwidth in the signal branch and 45% bandwidth in the idler branch when a periodically poled KTP crystal was pumped by a chirped Ti:sapphire laser with 12 nm full width at half maximum bandwidth. © 2003 American Institute of Physics.
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Marcus, G., Zigler, A. & Henis, Z. Third-harmonic generation at a atmospheric pressure in methane by use of intense femtosecond pulses in the tight-focusing limit. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 16, 5, 792 - 800 (1999).Abstract
An experimental study of third-harmonic generation in methane with a 100-fs, 820-nm, Ti:sapphire laser in a tight focusing geometry is presented. The harmonic intensity and bandwidth were measured in a range of intensities extending from below to far above the first ionization threshold and at pressures as high as 10 atm (1 atm = 760 Torr). The harmonic signal follows a power-law dependence on laser intensity with an exponent of similar to 7 and saturates at an intensity I-s similar to 4 x 10(14) W/cm(2). The conversion efficiency was found to increase with the pressure for laser intensities smaller than the saturation intensity I-s and to decrease with the pressure at larger intensities. At laser intensities larger than the saturation intensity a substantial modification in the third-harmonic bandwidth and structure was observed. (C) 1999 Optical Society of America [S0740-3224(99)00905-4].
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