Experimental and theoretical research on laser diode side-pumped Tm,Ho:YAG laser

A compact high-power laser diode (LD) side-pumped Tm,Ho:YAG laser at 2.09 μm was experimentally and theoretically investigated. Using a Tm,Ho:YAG crystal rod with a high dopant concertation ratio (3.0 at.% Tm³⁺ and 0.1 at.% Ho³⁺) and carefully optimizing the laser system design, a maximum continuous-wave (CW) output power of 87.7 W was achieved at a near room temperature (RT) of 12 ℃, corresponding to an optical-to-optical (o–o) efficiency of 13.3% and a slope efficiency of 21.2%. To the best of our knowledge, this represents the highest output power ever reported for a Tm–Ho co-doped solid-state laser. Furthermore, we numerically analyzed the multimode laser operation with a modified co-operative up-conversion rate. The agreement between the simulation results and the experimental data indicated that a high dopant concentration ratio with low up-conversion losses was favorable for achieving high-power output of the Tm,Ho:YAG lasers, thus paving the way for further advancements in Tm–Ho co-doped lasers.