Polarization-independent holographic gratings based on azo-dye-doped polymer-dispersed liquid-crystal films

Abstract

We demonstrate polarization-independent holographic gratings (PIHGs) based on azo-dye-doped polymer-dispersed liquid crystal films. The PIHGs are recorded by irradiation under an intensity-modulated interference field, generated by two linearly polarized green optical beams, and by simultaneously applying a suitable AC voltage to the sample. The photoexcited azo dyes are adsorbed onto the UV-cured polymer film with their long axes parallel to the normal of the substrate. When the applied voltage is switched off, the PIHGs are generated with periodic modulation of liquid-crystal structures with transparently homeotropic and randomly scattered alignments. Additionally, the generated PIHGs can be completely switched off by an applied voltage.

Preparation, optical properties and 1 × 2 polymeric thermo-optic switch of polyurethane-urea

“…Azo polymeric materials incorporating azobenzene moieties have attracted considerable attention owing to their potential technological applications, such as optical storage [1], holographic image storage [2], optical switches [3], optical computation [4], surface relief refractive and index gratings [5], liquid crystal alignment [6] and optical diffraction devices [7] among many others. In the last few years, a large amount of papers about the designing and synthesizing azopolymers have been reported.…”