Compensation of phase-matching dispersion in generation of nonmonochromatic radiation harmonics. I. Doubling of neodymium-glass radiation frequency under free-oscillation conditions

An efficiency of ~3% was obtained in generation of the second harmonic of nonmonochromatic neodymium laser radiation in an LiIO₃ crystal. The laser was operated under free-oscillation conditions and the dispersion of phase matching was compensated by a diffraction grating. An investigation was made of the angular and spectral characteristics of the harmonic radiation. It was found that compensation of the phase-matching dispersion widened the harmonic spectrum from 0.2–0.3 nm to half the width of the laser spectrum.