Generator of infrared radiation at the second-harmonic frequency of a TEA CO2 laser

An investigation was made of the possibility of improving the energy characteristics of infrared radiation generators operating at the second harmonic of a TEA CO₂ laser and utilizing nonlinear ZnGeP₂ crystals. Optimization of all the factors governing the efficiency did not, at present, raise the internal second harmonic generation efficiency in ZnGeP₂ above 20%. Homogeneous large ZnGeP₂ crystals (15–20-mm diameter, 10-mm long) of high optical quality were grown. Frequency conversion of wide-aperture beams in these crystals made it possible to generate infrared radiation with an energy per pulse of 0.16 J.