Research On Thermal Effect In Surface Gradient Doped Ceramic Slab Laser

The LD pumped solid-state laser is one of the main ways to achieve high-power laser output.With many characteristics,it is widely used in equipment manufacturing,high-precision medical,military and other fields.In order to improve the laser output,it is necessary to improve single gain medium output performance.However,the uneven heat distribution within the medium limits the laser output.For this reason,researchers have made many improvements in the gain medium.Such as changing the doped ions from Nd³⁺to Yb³⁺;using slab and thin-disk gain medium.And the emergence of laser ceramics has made more complex configuration designs possible.In this paper,combining the advantages of gradient doping and surface doping slab,a new structure of Yb:YAG ceramic slab is designed to improve the uneven heat distribution inside the slab and improve the output capability of the laser.Theoretically,the absorption of the pumping light by the laser gain medium is first analyzed.Based on this design,the configuration of the surface gradient doping is calculated.According to the solution results,the actual absorption of the pumped light was simulated and the corresponding thermal model was established.By using the finite element method,the temperature,thermal stress and wavefront distortion were calculated.The maximum stress was reduced by 26.2%,and the maximum temperature reduced 16.4°C and improved uniformity by 34.95%.In experiment,a surface doped Yb:YAG slab laser test platform was built to verify the established model.The wavefront detector and thermal imager were used to test the temperature and laser wavefront of the slab.In order to verify the feasibility of surface-doped ceramic slab,the laser output performance of single and double sided surface-doped ceramic slabs were tested respectively.A 7.6J laser output with O-O efficiency of 19.1%and a 3.04J output with O-O efficiency of 30.4%were obtained.The test data is similar to the theoretical simulation data,which validates the model.It shows that the surface gradient doped Yb:YAG laser ceramic is expected to improve the uneven heat distribution inside the medium and improve the laser output.