Sellmeier equations for GaS and GaSe and their applications to the nonlinear optics in GaSxSe(1-x).

The Sellmeier equations for GaS and GaSe are constructed from the nonlinear experiments thus far reported in the literature. The model calculations based on these equations were found to reproduce well the phase-matching conditions for second-harmonic generation of the Er:YSGG laser at 2.7960 μm and the CO2 laser lines at 9.5862 and 10.5910 μm achieved in the GaSxSe(1-x) crystals having different S concentrations of 0.004-0.412.