Thermal management of a CW dual-slab side-pumped high-power laser based on the optical path difference

Abstract

This study investigated the thermal management of a continuous-wave (CW) dual-slab side-pumped high-power Nd:YAG laser, optimizing the cooling channel design to enhance performance. We highlight the critical roles of the cooling channel thickness, coolant flow velocity, and coolant medium type in minimizing the temperature gradient, optical path difference (OPD), and thermal stress within the active medium. We derived an equation to calculate the OPD caused by thermal stress in a side-pumped laser. Our findings indicate that an optimal cooling channel thickness of 0.5 mm effectively balances heat dissipation with mechanical integrity. Furthermore, increasing the coolant flow velocity markedly reduces the OPD and thermal gradient. We established that the relationship between the fluid inlet velocity and OPD is nonlinear, with a reduction in OPD from 13.1 to 6.71 μm as the fluid velocity increases from 0.2 m/s to 0.6 m/s. Comparative analysis revealed that the use of heavy water instead of pure water reduced the thermal gradient, enhanced the beam quality, and reduced the thermal stress. The transition from pure water to heavy water at optimal conditions reduced OPD from 10.2 to 9.47 μm, underscoring the potential of advanced cooling solutions in laser applications.