Switchable random laser from dye-doped polymer dispersed liquid crystal waveguides

A dye-doped polymer-dispersed liquid crystal (PDLC) film has been fabricated for random lasing action. In this PDLC film, the sizes of most liquid crystal (LC) droplets ranged from 200 to 500 nm. When the sample is optically pumped, ultrahigh Q (>10000) lasing modes and a collimated laser beam can be observed. The threshold of the random laser is shown to be 0.23 mj/cm ². Additionally, a 9.2-V/μm external electric field was applied to control the orientations of LC molecules, thereby obtaining a switchable random laser. Consequently, the linewidth, intensity, and polarization of the emitted random laser are controlled.