Semiconductor Physics, Quantum Electronics & Optoelectronics. 2006. V. 9, N 1. P. 063-067.
New fast-relaxed liquid crystal materials
for optical communication networks
Institute of Physics, NAS of Ukraine, 46, prospect Nauky, 03028 Kyiv, Ukraine
Phone: 525-78-41; e-mail: klimush@iop.kiev.ua
Abstract. Recording the dynamic holograms with microsecond relaxation times under
action of laser pulses was obtained in composites based on the novel class of liquid
crystals (LC), namely in ionic metal-alkanoates. Holographic parameters of the recording
and relaxation characteristics were studied for doped lyotropic ionic LC and sandwich-
like cells with photo-sensitive impurities for purposes of real-time dynamic holography
applications. The thin cells demonstrate high-velocity dynamic grating recording under
laser pulses both of nanosecond and picosecond durations at the visible wavelengths. The
cells exhibit a fast temperature relaxation time (with the time constant 30 μs for the store
heat density more than 50 kJ/s). Ionic lyotropic smectic LCs possess a high intrinsic
anisotropic conductivity as compared with other LCs – dielectrics. To explain the
relaxation mechanisms in ionic smectic LC matrix, the temperature dependences of the
electro-conductivity have been investigated. The charge currier mobility and activation
energy in cells were estimated. The mechanism of high-velocity resonance nonlinearity
due to the saturation of excited states in photosensitive centers and mechanisms of the
grating erasure connected with charge transport in the ionic LC matrix were discussed.
Keywords: ionic smectic liquid crystals, dynamic holographic recording, liquid crystal
electrolyte, high-velocity process.
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