THIN UPPER-CONFINING LAYER ALXGA1-XAS-GAAS QUANTUM-WELL HETEROSTRUCTURE LASER-DIODES

AlxGa1-xAs-GaAs quantum well heterostructure (QWH) laser diodes with much thinner upper confining layers (0. 6, 0.45, 0.3, and 0. 2 mum) than usual ( 1 -2 mum) are demonstrated. The diodes exhibit well behaved transverse far-field patterns, low broad-area pulsed threshold current densities, and high differential quantum efficiencies. The diodes with thinnest upper confining layers, approximately 0.2 mum, have broad-area pulsed threshold current densities as low as J(th) approximately 169 A/cm2 and a total external differential quantum efficiency eta(T) approximately 53% 500 mum long cavities). Stripe-geometry (40 mum wide) laser diodes made from the crystals with 0.2 mum upper confining layers exhibit room-temperature continuous (cw) threshold currents of 60 mA, output powers of approximately 200 mW/facet (uncoated), and transverse far-field patterns with a full angle half power (FAHP) of 48-degrees. Nonoptimized narrow-stripe (approximately 4 mum) native-oxide index-guided laser diodes fabricated on the same 0.2 mum confining layer QWH crystal operate at pulsed thresholds as low as 9 mA and continuous thresholds of 16 mA, with total external differential quantum efficiencies of 39% pulsed and 30% cw.