High-Performance Planar Native-Oxide Buried-Mesa Index-Guided AlGaAs-GaAs QuantumWell Heterostructure Lasers

摘要

High-performance planar buried-mesa index-guided AlGaAs-GaAs quantum wellheterostructure (QWH) lasers have been fabricated by oxidation (H2O vapor + N2 carrier gas, 425-525 deg C) of a significant thickness of the high composition A1xGa1 -As upper confining layer (outside the active stripe). The oxide provides excellent current confinement for low-threshold laser operation and a low refractive index (n-1.6) for transverse optical confinement and index guiding. Laser diodes with -4,um-wide active regions exhibit 300 K continuous (cw) laser thresholds of 8 mA, with single longitudinal mode operation to 23 mW/facet, and maximum output powers of 45 mW/facet (uncoated). Devices fabricated on a lower confinement AlxGal-xAs-GaAs QWH crystal (x<-O.6 instead of x>-O.8) with -4 /im-wide active stripes exhibit 300 K cw thresholds of 9 mA and total external differential quantum efficiencies of 66%. Peak output powers > 80 mW/facet (uncoated) with linear L-I characteristics over the entire operating range are observed. In limited lifetest these laser diodes have been operated > 500 h without significant degradation.