Research And Design On 2.1μm Optical Parametric Oscillators

2μm laser has the ability to penetrate atmosphere and fog which made it presented more and more comprehensive prospects for a wide range of applications including laser radar, laser ranging,remote sensor and medicine diagnosis,so that it has received considerable attention from many researchers.Meanwhile,2μm laser is the ideal pump source of 3-5μm OPO.2.1μm OPO pumped by a Q-switched pulsed Nd:YAG laser is theoretically and experimentally studied.Theoretically,on the basis of coupled wave equations,OPO system is studied and some key parameters such as threshold and conversion efficiency are analyzed;the parameter of crystal KTP such as Phase matching methods,effective nonlinear coefficients,cutting angle and walk-off angle are calculated and analyzed,the system of OPO is designed.Experimentally,the investigation of single pass pumped light beam OPO and with return pass pumped light beam OPO are presented respectively,laser of 2.1μm are both achieved.The 2126 nm central wavelength parametric light is achieved by using single pass pumped light beam OPO,and the parametric light pulse is narrower than the pump pulse. The latter experiment is effective lower the OPO's threshold,the length of OPO compact on OPO's threshold and on the output light energy are discussed.Besides,by using crystal KTA instead of crystal KTP as the parametric oscillator crystal,laser at 2.1μm is also achieved.