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.
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].
I Segal, E Dorfman, O Yoffe, I Bezrukavnikov, and AJ Agranat. 2000. “
Direct ICP-OES Determination of Cu, Fe, Li, Ti and V in Potassium Lithium Tantalate Niobate Crystals.” Atomic Spectroscopy , 21, 2, Pp. 46-49.
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.
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.
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.
