High pump efficiency of a second-order distributed feedback laser based on holographic polymer dispersed liquid crystals with preferred liquid crystal molecular orientation

Abstract

We report on the fabrication and characterization of a surface-emitting distributed feedback (DFB) organic semiconductor laser based on a holographic polymer dispersed liquid crystal (HPDLC) transmission grating. Specifically, by adopting an acrylate-based monomer with low functionality and a narrower grating, the phase separated liquid crystal (LC) molecules were aligned along the direction of the grating groove, which can exhibit better lasing feedback performance in the HPDLC layer. The device shows single-mode laser emission at 630.4 nm with a threshold of 0.18 μJ, and the conversion efficiency is 6.4%. The curing intensity, light loss and diffraction efficiency were also investigated for HPDLC structures to identify the effects of the grating period and monomer functionality.