Research On Pulsed Solid State Laser

Pulsed solid state lasers are widely used in laser cutting,laser welding,laser remote sensing,satellite communication,biomedical and other fields.In this paper,the distribution of beam mode is studied and the 1.064μm laser output with high beam quality is obtained by starting from Nd.YAG pulsed solid-state lasers.The optical parametric oscillator(OPO)is further studied by using nonlinear crystal effect,the output of 1.57μm band laser is obtained in the end.The specific research contents are the followings:(1)Based on the theory of self reproducing,the self reproducing theoretical model under different cavity conditions is established.The distribution of output beam modes of flat-concave stable resonator,Gauss unstable resonator and Gauss unstable resonator based on hard-edge aperture is simulated theoretically.The effects of cavity length,crystal position and other parameters on the distribution of mode are analyzed.According to the results of theoretical simulation,it is concluded that the Gauss unstable resonator can effectively suppress the generation of higher-order modes compared with the flat-concave stable resonator.The mode distribution of the unstable Gauss resonator can be further improved by choosing the appropriate size and the appropriate position of the aperture in the resonator,and the uniform and smooth distribution of transverse mode can be obtained.(2)The resonator parameters of flat-concave stable resonator,Gauss unstable resonator and internal hard-edge aperture Gauss unstable resonator Nd:YAG pulsed solid-state laser are selected respectively,and the resonator parameters are optimized.Experiments on Nd:YAG pulsed solid-state lasers with stable and unstable resonators are carried out.The characteristics of output parameters of laser under different cavity types are analyzed.It is concluded that the Gauss unstable resonator improved the beam quality obviously compared with the flat-concave stable resonator.The pulse width and the maximum output energy of 1.064μm output laser is respectively 13.1ns and 330mJ under the condiction of 900v pump voltage.(3)The parameters of OPO unstable resonator,such as curvature radius of cavity,cavity length,transmittance of coupling output mirror and the size of crystal,are optimized.The appropriate KTP matching mode is selected and the optimal resonator parameters are designed.The intracavity Nd:YAG/KTP laser pumped by pulsed xenon lamp is experimentally studied.The effects of the curvature radius of the cavity mirror and the transmittance of the output mirror on the output laser energy and pulse width are studied respectively.The 1.57μm laser with a pulse width of 2.4 ns and a maximum output energy of 47 mJ was obtained under the conditions of the convex mirror curvature radius of-8000mm and the output mirror transmittance of 70%.The output power,pulse width and spectrum of LD-pumped intracavity Nd:YAG/KTP laser are measured,when the pump current is 125A,the output of 1.57μm laser with an average power of 4.67W and a pulse width of 4.3ns is obtained.