PLANAR NATIVE-OXIDE ALXGA1-XAS-GAAS QUANTUM-WELL HETEROSTRUCTURE RING LASER-DIODES

Native-oxide planar AlxGa1-xAs-GaAs quantum well heterostructure ring laser diodes (25-mu-m- wide annulus, 250-mu-m inside diameter, 300-mu-m outside diameter) are demonstrated. The curved cavities (full-ring, half-ring, and quater-ring) are defined by native oxidation (H2O vapor + N2 carrier gas, 450-degrees-C) of the entire upper confining layer inside and outside of the annulus. The native oxide provides current confinement and a sufficiently large lateral index step, and thus photon confinement, to support laser oscillation along the ring. Half-ring laser diodes fabricated in a self-aligned geometry exhibit continuous wave (cw) 300-K thresholds as low as approximately 105 mA (approximately 500-mu-m circular cavity length), high total external differential quantum efficiencies (approximately 49%), and cw output powers of > 40 nW.