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

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 th at influence the strength of this effect. Next, a theoretical model based o n rate-equation analysis is presented for threshold and efficiency calculat ions. The method is then applied to the analysis of Cr4+:forsterite and Cr4 +:YAG lasers. Experimental pump absorption, laser threshold, and laser effi ciency data are evaluated to determine the best-fit values of the absorptio n, 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 maximi ze the laser output power. Finally, the optimization algorithm is applied t o the study of a hypothetical solid-state gain medium to investigate how th e optimum crystal and resonator parameters vary as a function of absorption and emission cross sections. (C) 2001 Optical Society of America.