Dpl Heat Capacity Laser Medium Thermal Effects And Laser Characteristics

When the heat capacity laser is lasering, the waste heat is stored in the laser medium. The waste heat is removed in the cooling period. The mode of heat capacity manage is different from the mode of traditional real-time cooling about the temperature, stress characteristics in laser medium and laser output characteristic. For mastering the basic working rule of heat capacity laser, the output characteristic and thermodynamic characteristic of laser medium in course of lasering were studies by theoretical analysis, numerical simulation and experiment research, which will provide references for the experimental study and design of heat capacity laser. There were supports for the development of heat capacity laser.The Nd:YAG and Nd:GGG crystal were simply introduced. The Nd:YAG has many advantage in optical characteristics, thermal property and mechanical characteristics. But it couldn't get bigger size, so it limited the use of the Nd.YAG crystal in heat capacity laser. The Nd:GGG crystal is not as good as the Nd:YAG crystal in thermodynamic characteristic. But the mechanical intensity and thermal conductivity of Nd:GGG crystal is better than that of Nd:glass, and the Nd:GGG crystal could get bigger size. So the Nd:GGG crystal attracted significant attention in heat capacity laser study.The theoretical model of heat capacity laser output characteristic was established. The relation of the output power, the temperature and time was got. The results of numerical simulation shown: when the temperature of the Nd:YAG laser medium with 0.6at% Nd doped increased from 300K to 400K, the threshold power density increased from 2.6W/cm~3 to 33.6W/cm~3 and the output power reduced 7%; when the temperature of the Nd:GGG laser medium with 0.6at% Nd doped increased from 300K to 400K, the threshold power density increased from 2.3W/cm~3 to 29W/cm~3.The thermodynamic model was established for analyzing the distribution and variety of the temperature and the thermal stress in laser medium. The transient heat conduction equation is the base of the model. First, the longitudinal distribution of the heat deposition power density was got, and then it was loaded on the corresponding pumping part. According to the relation of the heat capacity, the thermal conductivity, the thermal expansion coefficient and the elastic modulus of the laser medium, the distribution and the variation of the temperature and the thermal stress in laser medium were got. The numerical simulations about Nd:YAG crystal and Nd:GGG crystal at different pumping conditions have been done. Andthe thermodynamics working conditions of heat capacity laser were confirmed.The 35OW Nd:YAG heat capacity laser and the 1380W Nd:GGG heat capacity laser were introduced respectively. The output powers at different repetition rate were measured and compared with calculation. The higher duty cycle was, the fast the output power reduced. The simulating result accorded well with experimental data at low duty cycle, but have relative bigerror at higher duty cycle.