CO₂laser frequency doubling in a new nonlinear AgGa_<i>x</i>In_1-<i>x</i>Se₂crystal

Abstract

The optical properties of a new promising nonlinear mixed AgGaxIn1-xSe2 crystal were investigated. Its absorption coefficients and refractive indices were determined at wavelengths 0.8 — 19 μm. For the first time the coefficients of the Sellmeier dispersion equations were determined for different indium contents. The corresponding phase-matching diagrams for second-harmonic generation and an optical parametric oscillator pumped by a Er3+:YAG laser were calculated and plotted. An experiment on the generation of the second harmonic of a TEA CO2 laser and a Q-switched laser was carried out and a frequency doubling efficiency of 10.9% was obtained. AgGaSe2 and ZnGeP2 crystals were also investigated for comparison.