High-efficiency, continuous-wave, epitaxial surface-emitting laser with pseudomorphic InGaAs quantum wells

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Abstract
We report the first continuous-wave (cw) photopumped operation of surface-emitting lasers comprising pseudomorphic InGaAs quantum wells. The lasers were grown by molecular beam epitaxy and incorporate epitaxial quarter-wave AlAs/GaAs mirrors surrounding an active region. In the active region, 50 Å InGaAs quantum wells are distributed with half-wave periodicity to center on cavity standing wave maxima. Lasing is observed from 78 to 250 K in the spectral range 920–950 nm, where the GaAs substrate is transparent. Thresholds were as low as 1.5×104 W/cm2, and overall (differential) output power efficiency was as high as 35% (85%) with up to 60 mW in a low divergence beam. Both periodic gain and biaxial compressive layer strain contribute to the reduced lasing threshold. The laser gain length is only 550 Å (11 quantum wells). The possibility of surface-emitting lasing in single quantum wells is discussed.