Abstract:A temperature tunable infrared optical parametric oscillator (OPO) based onMgO∶L iNbO3 crystal pumped by an electro optically Q2switched Nd∶YAG laserwith frequency-doubling crystal KTP is discussed. The OPO crystal is non-critically phase matched. When the output mirror with high reflection at the pump wavelength is used, the threshold value is lowed clearly, and the conversion efficiency is imp roved by 2 percent.