Rapid Optical Switching by Means of Photoinduced Change in Refractive Index of Azobenzene Liquid Crystals Detected by Reflection-Mode Analysis

Abstract

Optical switching behavior of low-molecular-weight and polymer azobenzene liquid crystals (LCs) was explored by means of reflection-mode analysis. Reflectivity changed on pulse irradiation under various conditions of orientations of LC molecules with respect to incident probe light, either s-polarization or p-polarization. For the low-molecular-weight LCs, we obtained a response time of 100 μs, which was very similar to that observed in the transmission-mode analysis, while we observed a decay time of 1 ms, which was significantly shorter than that observed in the transmission-mode analysis. The fast decay may be due to diffusion and reorientation processes which are characteristic of the reflection-mode analysis. For the polymer LCs, we observed a much slower decay than those for the low-molecular-weight LCs.