Effect of alignment layer on polymer-dispersed liquid crystal random laser

Abstract

The surface orienting effect of rubbed polyimide alignment layer on the random lasing (RL) properties of dye-doped polymer-dispersed liquid crystal (DDPDLC) was studied experimentally. Two groups of experiment were done and nematic liquid crystal E7 was used. In the first group, the samples were 25 μm non-oriented DDPDLC sample (N-DDPDLC) and 25 μm one-side oriented DDPDLC sample (P-DDPDLC). In the second, the samples were 10 μm N-DDPDLC and 10 μm P-DDPDLC sample. The results showed that compared to the N-DDPDLC, P-DDPDLC has a lower threshold, and the 10 μm P-DDPDLC has a lower threshold compared to the 25 μm P-DDPDLC. Apparently, the P-DDPDLC cell has stronger RL spike. The oriented layer changed the phase separation structure of DDPDLC which formed hierarchical structure so as to enhance the scattering intensity of system. It is a good way to reach high efficient random laser emission by tailoring the size and morphology of PDLC through surface orientation and Polymerization-induced phase separation process.