Bichromatic optical switch of diffractive light from a BCT photonic crystal based on an azo component-doped HPDLC

This study demonstrates all optical switches between the four diffractive light levels of a body-centered tetragonal photonic crystal. The sample is based on holographic polymer-dispersed liquid crystals that are fabricated using a two-beam interference with multiple exposures. The switching mechanism bases on the effective index modulation of the PC that contains a liquid crystal/azo-dye mixture could be controlled by two pumping laser beams. The switching time between the blue-laser-pumped and the blue-and-green-laser-pumped levels is fast. The study also discusses the switching time of the various levels.