High-power high-efficiency quasi-CW Sb-based mid-IR lasers using 1.9-μm laser diode pumping

Power efficiency is a critical issue for mid-infrared (mid-IR) semiconductor lasers. Previously, the highest power and efficiency 4-mu m laser was pumped with 0.98-mu m laser diode. This letter used 1.9-mu m diode pumping for better quantum defect ratio and heat flow geometry. A 3.7-mu m InAsSb-AlAsSb laser yielded a pump-power-limited 1,25-W single-ended output in 1-ms-long pulse with 6.5% net optical-to-optical efficiency, in contrast with a 0.67-W thermally limited output and 2.7% efficiency with 0.98-mu m diode pumping, at 70 K. The results are believed to represent the highest quasi-continuous-wave power from a single device, highest efficiency, and, scaled to the emitting aperture, highest power density for any 3-4-mu m semiconductor laser for 1-ms pulse and greater than or equal to 70 K.