| In this paper,the direct pumped Nd:YLF solid-state laser is studied.The numerical simulation method of the InnoSlab hybrid cavity,the thermal effect of the Nd:YLF crystal and the high power laser output of the 1047nm wavelength in the quasi continuous and continuous state are also studied.Aiming at the problem of pump optical coupling,a large aperture pump optical coupling system is designed to achieve 1047nm laser output.The main research results of this paper include:1)The development of solid-state laser,the principle and advantages and disadvantages of traditional pumping method and direct pumping method,as well as the research progress and current situation of direct pump technology at home and abroad are introduced.2)The structure of InnoSlab hybrid cavity is realized by Matlab calculation and simulation,and the pump coupling system of large aperture light spot is designed by Zemax software.In the design of the resonator,the structure of the InnoSlab hybrid cavity is adopted.In the horizontal direction,it is a confocal off-axis unstable cavity and a flat concave stable cavity in the vertical direction.In the design of the pump coupling system,a double rectangle lens and a cylindrical lens are used to shape the pump spot into a rectangular spot with a size of 15mm*0.8mm.3)The thermal effect of the slab is analyzed and simulated.First,the temperature distribution on the crystal is analyzed under the direct pumping mode and traditional pumping mode,and the influence of the pump band width and the crystal doping concentration on the temperature distribution is compared.Secondly,the thermal stress distribution on the crystal is analyzed,and the pump power limit of different pumping modes is calculated.Finally,the focal length of thermal lens in the crystal is calculated,and the relationship between the thermal lens focal length of the crystal and the pump power is analyzed.4)The output and beam quality of two cavity shapes in a flat concave cavity and a InnoSlab mixed cavity are studied.In the study of the flat concave stable cavity,the output transmittance was compared with the endoscopy of Tout=20%and Tout=30%respectively.In the case of Tout=20%output transmittance,the 1047nm quasi CW output power of the maximum 34W is measured,the slope efficiency and the optical efficiency are 39.21%and 26.39%respectively.In addition,the experiment also compares the output effect of different output coupling rate and different cavity length.In the experimental study of InnoSlab mixed cavity,two states of 1047nmnm quasi continuous laser output and 1047nm continuous laser output are studied.In the quasi continuous output state,the 1047nm quasi CW output power of the maximum 17W is measured,and the slope efficiency and the optical efficiency are 19.77%and 13.70%respectively.The spectral width of the 1047nm quasi continuous laser is 0.4nm,and the beam quality factor M2 is 3.556.In continuous output state,the highest output power of 44.19W is observed,and the slope efficiency and luminous efficiency are 15.9%and 12.32%,respectively.According to current reports,this is the highest laser output power obtained by direct pumped Nd:YLF solid state laser. |
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