Mid infrared, optically pumped, unstable resonator lasers

摘要

The authors describe high-brightness, broad area midinfrared semiconductor lasers. These devices were fabricated in the authors' laboratory using a commercial solid-source molecular beam epitaxial system. The laser structures incorporated 14 type-Ⅱ quantum wells embedded in thick waveguide/ absorber regions composed of In_(0.2)Ga_(0.8)As_(0.18)Sb_(0.82). The optically pumped devices achieved higher brightness operation as unstable resonators. Each unstable resonator was realized by polishing a diverging cylindrical mirror at one of the facets. For an unstable resonator semiconductor laser operating at ～4.6 μm, near 84 K, and at a peak power of 6.7 W, the device was observed to be nearly diffraction limited at 25 times threshold. In comparison, a standard Fabry-Perot laser was observed to be many times diffraction limited when operated under similar conditions.