Electrically switchable and thermally erasable biphotonic holographic gratings in dye-doped liquid crystal films

High-resolution laser-induced BGs based on azo-dye-doped liquid crystal (LC) films were developed and studied. The biphotonic gratings (BGs) were created by the irradiation of a red interference field written by two linearly polarized lights and one linearly polarized green light. A separate experiment verified that the BGs are formed by two mechanisms: first, the green-light-induced adsorption effect via trans-cis isomerization, and second, the inhibition effect of dye adsorption induced by the red light through the cis-trans inverse isomerization. In addition, the BGs were found to have two significant properties: electrical switching and thermal erasability.