Evaluation of the Performance of an HO:yap Laser Resonantly Pumped by a Thulium Fiber Laser

We investigate the continuous-wave performance of an Ho:YAP laser resonantly pumped by a Tm fiber laser at different output transmittance of 20 %, 30 %, and 50 %. We use a 40 mm long a-cut crystal with 0.5 at.% Ho ion. Our experimental results show that the best power performance is obtained at an output transmittance of 30 %. At an absorbed pump power of 12.1 W, we obtain a maximum output power of 6.1 W at 2118.1 nm with a slope efficiency of 63.4 %. The laser operates at the TEM₀₀ mode with a beam quality factor M ₂ ~ 1.5 measured using a 90/10 knife-edge method.