Abstract

The buried heterostructure (BH) laser¹ is one of the most attractive index guided stripe geometry semiconductor lasers because of the combination of strong lateral index guiding and absolute current confinement provided by a heterostructure discontinuity in the lateral direction. This structure is difficult to fabricate, however, because of the need for processing high quality narrow stripe etched mesas with a high quality regrowth interface at the edges of the active region. The regrowth is especially difficult² for AlGaAs-GaAs BH lasers having higher aluminum composition confining layers. Various^1,3-8 AlGaAs-GaAs BH laser structures have been reported. In this work, we report the characteristics of long wavelength (λ> 1 μm) strained layer InGaAs-GaAs-AlGaAs quantum well buried heterostructure lasers^9-11 formed by wet chemical etching and a two-step MOCVD growth process. The relatively low aluminum composition of the confining layers allows for high quality regrowth interfaces and effective use^2,12 of a silicon dioxide mask for selective epitaxy limited to the etched regions. The structures reported here have active region stripe widths of ~3.5 μm, an emission wavelength of λ ~ 1.074 μm, and threshold currents of less than 7 mA (cavity length 405 μm). Output powers in excess of 130 mW per uncoated facet with total differential quantum efficiencies of greater than 60% have been observed. Near-field patterns indicate that the lasers are operating on a fundamental lateral mode and are stable to more than thirty times laser threshold.

© 1989 Optical Society of America