Harnessing Fick’s distribution in thermally diffused polycrystals for in-situ optimization of laser efficiency

Here, we report the doping profile engineering for laser ceramics via an empirical revision of Fick's diffusion model for Cr:ZnS, and its application to in-situ laser performance optimization. Using a 30% output coupler, the system achieved a maximum laser output power of 5.8 W and a maximum slope efficiency of 53.5%, reaching 81% of the intrinsic Stokes limit.

The output power is further amplified to nearly 10 W with an optimized trade-off between gain and thermal management, as previously noted, again enabled the ion concentration selection in a single-pass master oscillator power amplifier (MOPA) configuration. This approach is broadly applicable to thermally diffused gain media, paving ways for advancing high-efficiency and high-performance MIR laser sources for both fundamental research and industrial/medical applications.