Gain narrowing and random lasing from dye-doped polymer-dispersed liquid crystals with nanoscale liquid crystal droplets

Abstract

Dye-doped polymer-dispersed liquid crystals have been studied for random lasing. The dye-doped polymer-dispersed liquid crystal film was fabricated by photoinitiated polymerization with a collimated 514.5 nm Ar+ laser beam. Scanning electron microscopy analysis showed that most liquid crystal droplets in polymer matrix ranged from 20 to 80 nm. Gain narrowing and random lasing from dye-doped polymer dispersed liquid crystals were observed under the excitation of a frequency-doubled Nd:YAG (yttrium aluminum garnet) laser operating at a wavelength of 532 nm. The possible mechanism was proposed to explain the random lasing. The threshold of the random lasing was about 25 μJ/pulse. The linewidth of the lasing peaks was about 1 nm. With the film thickness of 6.5 μm, the lasing mode was nearly transverse electric polarized. © 2006 American Institute of Physics.