Numerical Simulation of Thermal Lens Effect in Laser Diode End-Pumped Solid-State “Quasi-Rotating” Lasers

To address thermal effects in end-pumped solid-state lasers, this paper introduces a new motion concept called “quasi-rotating” and proposes a specialized method for evaluating the thermal focal length of dynamic gain medium, which proves valuable for resonator design. Using the finite element numerical analysis method, we analyze the changes of the temperature field distribution within the crystal and demonstrate the effectiveness of the “quasi-rotating” cooling system in thermal management. The results show that the “quasi-rotating” frequency and pump power have a more significant influence on the thermal lens effect than the cooling water temperature. Compared to previous studies, our new method accurately predicts the thermal focal length of the moving crystal and provides direct guidance for resonator design, as shown in this paper. These findings provide a theoretical foundation for the design and enhancement of high-power solid-state lasers. Moreover, the approach offers meaningful insights for the design of other non-traditional lasers with dynamic gain medium.