Efficient generation of the second harmonic of tunable CO2 laser radiation in ZnGeP2

The second harmonic of CO₂ laser radiation was generated for the first time in ZnGeP₂ single crystals under phase-matching conditions when the pump (fundamental-frequency) radiation was tuned within the ranges 9.19–9.7 and 10.15–10.8 μ. A study was made of the spectral, angular, and temperature widths of the phase-matching curve, of the dependence of the efficiency of conversion to the second harmonic on the pump wavelength and temperature of a crystal, and of the rate of reduction in the phase-matching angle as a result of heating.