Investigation of linear and nonlinear optical properties of GaSxSe1–x crystals

The refractive index and the birefringence of GaS_xSe_1–x crystals were determined in the range 0.63–20 μ. Generation of the second harmonic of CO₂ laser radiation was used to determine nonlinear optical coefficients. Mixing of radiations from a YAG laser and a tunable F₂^–-center laser generated the difference frequency in a GaSe_0.8S_0.2 crystal and radiation of this frequency was tunable in the wavelength range 7–12.5 μ.