Theoretical Investigation on the 2.7iM Laser Pumped ZnGeP2 Optical Parametric Oscillator Generating Mid-Infrared Laser

The scheme of ZnGeP2(ZGP) optical parametric oscillator(OPO) generating 4.3μm laser with different phase matching types pumped by 2.1μm and 2.7μm laser respectively were presented in view of the important application value of mid-infrared laser. The phase matching angle, walkoff angle, effective nonlinear coefficient, allowable linewidth and divergence angle of pump laser, linewidth of output laser and absorption coefficient of ZGP to pump laser were calculated and compared. The results show that the optimal scheme to generate 4.3μm laser based on ZGP OPO is to use 2.7μm laser as pump source, which was generated by 1.06μm laser pumped KTP intra-cavity OPO, and with type Ⅱphase matching. The experimental scheme and proper parameters were presented. The effects of parameters on the threshold of ZGP OPO were analyzed. The results of theoretical calculation and preliminary experiment of 2.7μm laser show that it is feasible to generate 4.3μm laser by this method, which lays a foundation for the next step of 4.3μm laser experiment.