Thermal effect analysis on cuboid Pr:YLF crystals pumped by blue laser diodes

Using blue laser diodes (LDs) to pump Pr:YLF crystals can directly realize visible-band laser output. Compared with the traditional frequency doubling and LD direct output method, it has the advantages of simple design, compact structure, and high beam quality. For solid-state lasers, pump-induced thermal effects of gain media are the principal limiting factors for the desired high-power output. In this paper, internal temperature space model distribution of a rectangular cross-section Pr:YLF crystal is established. On this basis, the temperature distribution, thermal stress distribution, and thermal focal length variation of single-end pumped and double-end pumped laser crystals are analyzed. The results are verified by COMSOL simulations and experimental measurements. To our knowledge, this analysis is the first to examine the thermal effect of a rectangular cross-section Pr:YLF crystal, analyzing the limit power that the crystal can withstand, which paves the way for better performances of visible lasers with stable and high-power output.