Research On Solar-pumped Solid State Laser And Its Application

Solar energy has become one of the major new type energy sources for humanity in the future due to its abundant resources,clean use and huge reserves.Solar-pumped laser is a kind of equipments which can transform sunlight into laser directly,with the advantages of minimum energy transform process,high energy transform efficiency and long lifetime,which is suitable for application in no-man space.Base on sufficient survey of the domestic and international solar pump technology,the theoretical of solar-pump laser oscillation,laser amplification and multi-frequency laser were analyzed.The influence factors of the energy conversion efficiency and the temperature characteristic of the gain medium were analyzed,respectively.The solar-pumped laser oscillator,laser amplifier and multi-frequency laser were tested.Finally,a free space laser communication system with solar-pumped laser was proposed and the ground demonstration experiment was successfully completed.This thesis mainly covers these aspects:(1)The theoretical model of the laser oscillation technique was studied,and the system structure and basic composition of the solar-pumped laser oscillator were given.The solar pumping model and the laser resonator model was established with the help of the ray tracing software Trace Pro^@and the finite element analysis software LASCAD^@,which provide the theoretical basis for the optimal design of solar pump lasers.In order to further improve the efficiency and beam quality of solar laser,the thermal effects were analyzed and studied.(2)The experimental studies of a solar-pumped laser oscillator based on a Fresnel lens system and a parabolic mirror system were introduced,respectively.The liquid light guide lens,the grooved crystal rods and the Nd:YAG/YAG bonding crystal were designed.The record solar laser collection efficiency of 32.1W/m² was obtained,with the ground solar of980 W/m²,(3)Based on the theory of longitudinal mode selection of laser resonator,the relationship between the number of output longitudinal modes and the length of laser material was calculated.The microchip laser simulation model was established with the software of Tracepro^@and LASCAD^@.The distribution and absorption of sunlight in laser material were analyzed.The thermal effect,threshold power and output characteristics were studied.The LD-pumped and solar-pumped multi-frequency laser system was built and the controllable multi-frequency lasering was obtained.A single-frequency lasering with a linewidth of 16 KHz,a dual-frequency lasering with a frequence difference of about 74.4GHz and a three-frequence lasering with a frequence difference of about 34.3 GHz were obtained,respectively.(4)The theory of solar-pump laser amplification was studied.The threshold power and gain of the solar-pumped amplifier were calculated.The YAG/Nd:YAG/YAG bonding crystal for laser amplifier was designed.The gain of the solar pumped laser amplifier system was calculated and the thermal effects were analyzed.The experimental device of solar-pumped YAG/Nd:YAG/YAG laser amplifier was built,,and then made experimental study.(5)The study on the application of solar-pump laser was carried out and a low-threshold,high-efficiency and high-quality solar-pumped laser oscillator was developed.A free-space optical communication system based on a solar laser was built.During the testing of communication system,real-time transmission of high-definition video signals with a rate of higher than 125 Mbps and a bit error rate of less than 10^-6 was obtained.The feasibility of using solar-pumped laser for high rate communication application in free space was demonstrated for the first time.