Highly efficient lasing at difference frequencies in a nematic liquid crystal

Highly efficient lasing at difference frequencies is obtained in a nematic liquid crystal excited by several visible lines from a cw argon laser with a total power of 0.08 — 1.5 W. The maximum conversion efficiency was ~1% and the quadratic susceptibility was ~2 × 10^-6 m V^-1. The field of application of the approximate mechanism of quadratic nonlinearity and frequency conversion considered in the paper requires specification. The nonlinear conversion of radiation in a nematic crystal has specific features compared to lasing at difference frequencies in solid crystals.