Research On 1.6 μm Resonantly Pumped Single-frequency Laser Technology

1.6 μm belongs to the eye-safe band,and has a wide range of applications in lidar and free space communications.The physical and chemical properties of Er:YAG crystal are stable and have good thermal conductivity.It’s main emission wavelengths are 1.645 μm,1.617 μm and 3 μm.These advantages make it a typical working substance for 1.6 μm lasers.Therefore,how to design a 1.6 μm Er:YAG solid state laser with high conversion efficiency and beam quality is a hot issue for scholars at home and abroad.In this paper,we analyzed the output characteristics of Er:YAG laser by solving the rate equation.and carried out the experimental study of Er:YAG single-frequency laser and Q-switched laser.Based on the analysis of the simulation results,low-temperature resonant cavity and step-doped Er:YAG ceramic are used to improve the output characteristics of laser.Firstly,the research background and significance of this subject were described.The research status of coherent wind measurement radar and 1.6 μm laser were introduced.Then,the structure and thermal characteristics of the Er:YAG crystal were analyzed.Based on the principle of the resonant cavity,the parameters of the cavity structure are designedSecondly,the rate equation of Er:YAG laser was studied.The effects of laser parameters on the laser output characteristics and threshold power are simulated by Matlab,including the length,concentration,and temperature of the gain medium,as well as the pump wavelength and the transmission of the output mirror.Based on the basic principle of Q-switched laser,the pulse energy,pulse width and average power are analyzed in different repetition frequencies.the principle of frequency selection of F-P etalon and the non-planar ring cavity were introduced At the same time,some experimental research of the non-planar ring cavity laser and the Q-switched laser were conducted.Finally,following the principle of the same absorption efficiency o f each segment of gain medium,we designed Er:YAG ceramics.which were doped in 5,6,7,8,and 9segments,and determined the doping concentration of each segment.Next,temperature distribution of ladder doped Er:YAG ceramics were simulated by the heat source function.we designed the liquid nitrogen dewar for cryogenic refrigeration in Solidworks.