Study On The Thermal Effects Of Ld Side-pumped Nd:YAG Rod Laser

DPSSL are widely used in medical, optical communications, laser processing industry etc. because of their small size, reliability, efficiency and other excellent properties. With the coaction of pump field and coolant, the temperature gradient is formed within laser working medium, and then the thermal effects such as thermal lensing, thermal stress birefringence and so on are emerged, they all seriously restrict the development of lasers. In order to solve the problems including too much assumptions, simple simulation and unilateral analysis in today’s thermal effects analysis methods, the thermal analysis models were established in this paper. Using the ANSYS finite element method simulate the temperature distribution in Nd:YAG crystal. The the judgment method on uniformly temperature field distribution was set up, and the scheme was designed to compensate the thermal stress birefringence which was verified by the experiment. The main research contents are as follows:(1) The thermal effects mechanics were analysised at first, and then the physical and mathematical thermal analysis models were established based on the theoretical knowledge of thermal effects in LD side-pumped Nd:YAG laser, the Nd:YAG crystal’s optical field distribution was simulated by using MATLAB software.(2) The loading area of heat source function was calculated according to the thermal analysis models have been maded. The mean-variance criterion of temperature field distribution in crystal was put forward. The temperature distribution in laser working medium was simulated by using the ANSYS finite element method. How the parameters inculding Nd:YAG crysta’s characteristics, LDA parameters and cooling conditions affected the temperature field distribution were researched. At last, the analog results were achieved under the related parameters were optimized.(3)A λ/4wave plate was put between the laser head and output mirror to compensate the thermal stress birefringence based on the principle of thermal compensation, and then the experimental provision was established, we measured the power of output laser and recorded the laser spotes, the experiment result proved the thermal compensation method was right.