| High power (10 W) and high brightness semiconductor lasers at a wavelength of 975 nm are desirable for pumping of fiber lasers and solid state lasers. Current technology uses edge emitting diodes which have poor beam quality and are limited in power output due to catastrophic optical damage at the edge facets. Dr. Alan Paxton proposed a novel shaped unstable resonator design incorporated in a grating surface emitting laser in his previous work [1] and patent [2] as a possible structure to achieve high optical output power. This research is a continuation of Dr. Paxton's previous work. This thesis addresses the design, process development, epitaxial growth, and fabrication failures and successes of developing such a high power surface emitting laser.; The design of the quantum well laser structure that would support lasing at a wavelength of 975 nm was performed using custom software WAVEGUIDE and GAIN. For high power operation, issues to address included filamentation and spatial hole burning. Initial design efforts included a lens-like structure which would reduce these high power effects. Challenges in this work involved process development to fabricate the lens-like structure, fabricating second order gratings for outcoupling of the light, and developing a regrowth over gratings process that would result in a quality crystal that could support high power.; The program goal was to achieve 10 W of optical output power that was single mode and single frequency. Due to the scalable architecture of our structure, we planned to fabricate lower power devices in the 1 W range and scale the device length to increase the output power. After many iterations, 1.5 mm long devices demonstrated a single lobed far-field (0.54° x 4.6°) with single frequency (< 0.1 nm) operation (∼979 nm) and 500 mW of light output with a drive current of 5 A. This is exceptional performance considering that an equivalent commercial broad area laser has a bandwidth range of 2--4 nm and a beam divergence of 8° x 30°. |
