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Proceedings Paper

Low-threshold InGaAs/GaAs strained-layer quantum-well lasers (lambda=0.98 micron) with GaInP cladding layers grown by chemical beam epitaxy
Author(s): R. M. Kapre; Won-Tien Tsang; Ming C. Wu; Young-Kai Chen
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Paper Abstract

Strained InGaAs/AlGaAs quantum well (QW) lasers operating at 0.98 micrometers are currently of great interest due to their suitability for pumping erbium-doped fiber amplifiers. They are reported to yield a lower noise figure and higher gain coefficient than the 1.48 micrometers InGaAs/InP pump lasers as well as 0.8 micrometers AlGaAs/GaAs pump lasers. In addition, the InGaAs/AlGaAs strained QW lasers have lower threshold current, higher slope efficiency, and less temperature dependance. All these factors contribute to lowering the power dissipation of the pump design. Recently Ga0.51In0.49P, lattice-matched to GaAs has been introduced as a substitute for the AlGaAs cladding layers due to reports suggesting its resistance to rapid degradation by dark line defect propagation and to catastrophic mirror damage. The aluminum-free system also lends itself more readily to device fabrication by selective etching and epitaxial regrowth or mass transport. We report on the first InGaAs/GaAs strained-layer QW lasers using GaInP cladding layers grown by chemical beam epitaxy. The laser structure is a separate confinement heterostructure (SCH) with the active region consisting of 70 angstroms thick In0.2Ga0.8As quantum well and 220 angstroms thick GaAs barriers. The active and the SCH region are cladded by Ga0.51In0.49P layers of 1.35 micrometers thickness. A very low broad-area threshold current density of 70 A/cm2 was obtained for 1500 micrometers long single QW lasers which is among the lowest reported for InGaAs/GaAs/GaInP lasers. The Jth for two and three QW lasers were 135 A/cm2 and 170 A/cm2 respectively. Ridge waveguide lasers with 4 micrometers width have very low cw threshold currents: 7.8 mA for 500 micrometers -long cavity and 10 mA for 750 micrometers -long cavity. External differential quantum efficiency as high as 0.9 mW/mA was obtained for 250 micrometers -long lasers. From the slope of inverse quantum efficiency versus cavity length, a very low internal waveguide loss of 2.5 cm-1 and an internal quantum efficiency of 0.95 are inferred.

Paper Details

Date Published: 16 February 1993
PDF: 8 pages
Proc. SPIE 1788, Sources and Detectors for Fiber Communications, (16 February 1993); doi: 10.1117/12.141113
Show Author Affiliations
R. M. Kapre, AT&T Bell Labs. (United States)
Won-Tien Tsang, AT&T Bell Labs. (United States)
Ming C. Wu, AT&T Bell Labs. (United States)
Young-Kai Chen, AT&T Bell Labs. (United States)

Published in SPIE Proceedings Vol. 1788:
Sources and Detectors for Fiber Communications
Stephen D. Hersee, Editor(s)

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