Research And Design Of Mid-infrared Optical Parametric Oscillator Based On Optical Superlattice

3um-5um mid-infrared(MIR)laser has more and more demands in gas detection,biological medicine,laser lidar and aerial guidance with the development of laser industry.The optical parametric oscillator(OPO)is employed to more simply obtain the high coherent mid-infrared laser output with wide tuning range,high power and stable operation.After decades of research and development,quasi-phase matching(QPM)has achieved great prograss and maturation in OPO,and in the meanwhile,mid-infrared OPO products based on that enter the application market gradually.This thesis mainly demonstrated two different kinds of OPO based on QPM,including intra-cavity MIR OPO and picosecond MIR OPO.We have successfully obtained the working prototype that can achieve stable tuning output of mid-infrared laser in both experimental and using environment through the optimization of the optical and mechanical parts.The main content is summarized as the following parts:1.The development of laser and nonlinear optics are introduced,and the mode and principle of phase matching used in nonlinear frequency conversion are described.This thesis introduces the important application field and main generation method of middle infrared laser.And it also describes the research background and significance based on the advantanges of obtaining MIR laser with OPO.2.The basic principle,classification and calculation of different characterization parameters of OPO are introduced theoretically,including three-wave coupling equation,gain,threshold,conversion efficiency,line width and influence of thermal effect.The wavelength tuning mode and principle commonly used in OPO are introduced.The method of OPO cavity construction and the matters needing attention in the process are introduced.3.We have studied the continuous wave intra-cavity mid-infrared optical parametric oscillator with the ultra-small structure and high integration density.Through the experimental study of the linear intracavity structure pumped by the laser diode,we obtain a wide tunable and highly stable middle infrared laser output.Through desigh and optimization of the optical and mechanical structures continuously,we have realized a more simple and compact mid-infrared intra-cavity OPO prototype,with the far smaller volume that is 160mm*80mm*76mm than the previous prototype products and the more stable power output.4.We have studied a synchronous pumped picosecond mid-infrared parametric oscillator.Multi-period MgO:PPLN crystal was pumped synchronously by picosecond fiber laser to generate a tuning output of 2.6um to 4.2um in the middle infrared,in which the average power in the range of 2.8um to 3.8um was greater than 1W.Then,we adopted the way of cavity mirror folding to reduce the length and volume of the overall cavity in the desigh of the prototype,and finally successfully built a picosecond mid-infrared OPO that can be controlled by software to tune wavelength and power while that can work stably.