| Solar pump laser is a device that uses sunlight as a pump source and directly converts sunlight into laser.The method has the advantages of less conversion process,simple structure and high conversion efficiency,and has great application value in the fields of space communication and space energy transmission.In space laser communication,using each frequency of multi-frequency laser as the communication frequency of laser communication will increase the capacity of laser communication and increase the space laser communication rate.In this paper,the theoretical analysis of the sun-pumped Nd:YAG microchip multifrequency laser and the related experiments,the main research work are:The laser modes existing in the laser resonator are expounded.The influencing factors of the laser mode and the oscillation modes of the fundamental transverse modes are discussed.The selection of the transverse mode and the longitudinal mode in the laser cavity is analyzed.The laser oscillation theory of direct pumped solid-state laser is analyzed.The characteristics and performance requirements of solar pumping material are analyzed.The absorption coefficients and thermodynamic properties of Nd:YAG,Yb: YAG and Nd:YVO4 are compared.A method to compare the absorption coefficients of different working materials is given,that is,the absorption coefficient of each working substance is determined through the correlation numerical integration of the absorption power spectrum and the solar spectrum.The multi-frequency laser energy transmission model of the sun-pumped Nd:YAG microchip is established and the influencing factors of each energy conversion are analyzed.The selection principle of working substance under solar pumping is analyzed,and Nd:YAG is determined as working substance.The relationship between the length of working material and the number of longitudinal modes is deduced.Trace Pro software is used to simulate the light intensity distribution of sunlight on Nd:YAG microchip with different length.The LASCAD software was used to simulate the temperature distribution,pump energy density and laser output power of Nd:YAG microcrystal with different length.The Matlab software was used to simulate the variation of the spot radius with the radius of the output mirror.When the output mirror radius of curvature increased,the spot of the thermal lens in the laser cavity also increased.Based on the previous theory,this paper designs and sets up a semiconductor laser pump and a sun-pumped Nd:YAG microchip laser device.At 20 ?,One to three frequency outputs were obtained by LD pumped Nd:YAG laser crystals with thickness of 0.8mm,1.1mm and 2.4mm,respectively.a 60.3m W tri-band laser output was obtained at a pump power of 801 m W,with the spacing between adjacent two longitudinal modes being35.4GHz.Three longitudinal modes of the laser is detected by the wavelenghth meter.when the sunlight pumped Nd:YAG microchip. |
PDF Full Text Request