CHARACTERIZATION OF 2128 nm LASER WAVELENGTH FROM DEGENERATE OPTICAL PARAMETRIC OSCILLATOR OPO AND ITS APPLICATION

Abstract

An efficient conversion of 1micrometer to 2 micrometer has been demonstrated using High Grey Track Resistant Potassium Titanyl Phosphate HGTR KTP crystal based Optical Parametric Oscillator OPO, pumped by Q-switched Nd YVO4 laser at 10 KHz repetition rate to pump a ZGP crystal to get infrared radiation. The near degenerate wavelengths generated are 2.098 micrometer and 2.161micro- meter. The performance of the OPO was investigated by changing the crystal temperature, cavity length and changing the output coupler reflectivity. Optimum output power from this OPO was obtained at 34 mm cavity length, at 70 degree Celsius crystal temperature and at 80 percent output coupler reflectivity. Maximum output power of 7.5 W was obtained on incidence of 19.6 W pump power corresponding to 38.7 percent conversion efficiency. The peak output power obtained from the OPO was 127 kW. The measured values of the divergence of output beam was 3.7 mrad and 4.1 mrad in X and Y directions, respectively. newline During research work an application of newly available adhesive free bonded Potassium Titanyl Phosphate crystal is also reported. An optical parametric oscillator based on two Adhesive Free Bonded Potassium Titanyl Phosphate AFB KTP crystals in a walk-off compensated configuration has been demonstrated and investigated. Using Nd YVO4 as a pump source, a maximum average power of 3 watt has been achieved at a repetition rate of 10 KHz. The output wavelengths generated 2.127 micrometer and 2.131 micrometer show near degeneracy. The results show highly stable output with a slope efficiency of 26 percent. OPO threshold as low as 32 MW per square centimeter is achieved. Highly stable output power and good beam quality are the significant achievements of this OPO configuration. newline newline newline