Sellmeier equation and conversion of the radiation of a repetitively pulsed tunable TEA CO2 laser into the second harmonic in a ZnGeP2 crystal

The results are reported of measurements of the spectral dependences of the conversion efficiency and of the phase-matching angles in the conversion of the radiation of a repetitively pulsed TEA CO₂ laser into the second harmonic in ZnGeP₂ crystals. The measured angular phase-matching curves are compared in the range 9.2 — 10.8 μm with curves calculated, on the basis of the spectral dependences of the refractive indices for the ordinary and extraordinary waves, for several Sellmeier coefficients. The Sellmeier coefficients are in agreement with the measured values.