Transient photoinduced current in dye-doped polymer and polymer-dispersed liquid crystals

Results are reported on the experimental observation and detailed treatment of photoinduced de currents, which arise in both dye-doped polymer and dispersion of liquid-crystalline droplets in the same polymer under cw laser-beam illumination. These currents reveal transient behavior, i.e., a relaxation to zero value after an initial increase. This growth is monotonic by low Values of the laser radiation intensity, but it changes to oscillating behavior by higher values. A preliminary theoretical approach, which is based on experimentally observed features, reveals good qualitative agreement with current temporal-envelope measurements. The observation of these photoinduced currents is another evidence for the photorefractive nature of the light-induced diffraction gratings, which were observed earlier in the same materials.