Research On The Thermal Effect And Passively Q Switched Characteristics Of The Whole Cabity Water-cooled Radial Slad Solid-state Laser

High-power solid-state lasers, being famous for small size, high reliability, high conversion efficiency, have been widely used in military, medical, industrial processing, and other fields. Compared with rod solid-state lasers, slab solid-state lasers can achieve better beam quality, higher average output power and higher efficiency, and have long been favored by people’s concern.When the solid state laser is working, there will be a considerable part of the pump light transforming into heat and remaining in the laser medium. Generally, the way of cooling laser medium is external cooling, and it will bring about the phenomenon of uneven temperature distribution in the medium. The uneven temperature distribution and thermal stress caused by it will lead to a series of thermal effect problems. Therefore, it is necessary to study the temperature and stress distribution of the medium. This subject adopted radial-8-slabs laser medium around pumped by 8 xenon lamps. This medium can effectively increase the pump area and the heat cooling area. That is to say it can not only effectively improve the conversion efficiency of the laser but can effectively weaken the heat effect. At the same time, in order to obtain higher peak power and expand the application scope of the laser, this paper adopts the technique of passively Q-switch.The main research content of this thesis includes the theoretical analysis of the temperature and stress distribution of the medium and its numerical simulation, the theoretical and experimental research of the Q-switch technique, and the optimization design of the laser cavity. The concrete research content is as following:(1) The background and significance of the topic was stated. The research status both at home and abroad of the solid-state slab lasers, the thermal effect problem of the slab laser medium and some cooling ways were summarized. And the research situation of the passively Q-switched laser was introduced.(2) The description of the temperature field and the thermal stress and strain was introduced simply. The thermal analysis of radial-slab laser medium was researched theoretically. The temperature and thermal stress distribution of the radial-slab laser medium was simulated, and analyzed by using the ANSYS software under different conditions. Finally, the finite element simulation results of the temperature and stress distribution of the laser medium under practical experimental conditions was given.(3) The basic principle of the passively Q-switching was expounded. The basic properties, spectral characteristics, energy level structure and saturable absorption properties of the crystal Cr4+:YAG were introduced. The rate equation and its solution of the passively Q-switching using the crystal Cr4+:YAG were given. And the rate equation was simulated and analyzed(4) The pump cavity of the solid-state radial-slab laser was designed optimally. The normal operation of the solid-state radial-slab laser was achieved. Using the theory of matrix optics and the MATLAB software, flare focusing characteristics is analyzed, and based on this, the concrete position of the crystal Cr4+:YAG was determined and the passively Q-switch experiment of the solid-state radial-slab laser was conducted.