Analysis and optimization of lifetime thermal loading in continuous-wave Cr4+- doped solid-state lasers

Abstract

A systematic and rigorous method for the analysis and optimization of Cr4+-doped solid-state lasers subject to lifetime thermal loading is described. First, a figure of merit is derived to identify the important parameters that influence the strength of this effect. Next, a theoretical model based on rate-equation analysis is presented for threshold and efficiency calculations. The method is then applied to the analysis of Cr4+:forsterite and Cr4+:YAG lasers. Experimental pump absorption, laser threshold, and laser efficiency data are evaluated to determine the best-fit values of the absorption, emission, and excited-state absorption cross sections for the two laser media. Best-fit cross section values are then used to determine the optimum crystal length, crystal absorption, and resonator reflectivity that maximize the laser output power. Finally, the optimization algorithm is applied to the study of a hypothetical solid-state gain medium to investigate how the optimum crystal and resonator parameters vary as a function of absorption and emission cross sections.