Temperature Distribution in a Diode End-Pumped Solid State Laser Slab Subject to Two-Phase Spray Cooling

As diode pumped solid-state lasers become more powerful, improved thermal management techniques are required. Minimizing thermal gradients in the laser increases performance and reduces thermal stress, which can cause failure by fracturing. Two-phase sprays provide an isothermal cooling method capable of dissipating high heat fluxes produced by the laser. A three-dimensional model of a spray-cooled, end-pumped solid-state laser has been developed to examine the temperature distribution within the laser slab. The model includes variable multi-nozzle arrangements, spatial distribution of two-phase heat transfer coefficients within each spray pattern, and non-uniform heat generation. A study has been conducted to minimize the range of surface temperatures across the slab by varying nozzle spacing. Two-dimensional temperature profiles at the sprayed surface and at the slab mid-plane have been generated. Results indicate that two-phase spray cooling can remove large heat fluxes and maintain temperature variations within acceptable limits. A new technique for designing and analyzing two-phase thermal management systems for solid-state lasers has been developed.