Low-threshold 1.5 mu m compressive-strained multiple- and single-quantum-well lasers

Abstract

Design considerations for low-threshold 1.5- mu m lasers using compressive-strained quantum wells are discussed. Parameters include transparency current density, maximum modal gain, bandgap wavelength, and carrier confinement. The optical confinement for a thin quantum well in the separate-confinement heterostructure (SCH) and the step graded-index separate-confinement heterostructure (GRINSCH) are analyzed and compared. 1.5- mu m compressive-strained multiple- and single-quantum-well lasers have been fabricated and characterized. As a result of the compressive strain, the threshold current density is loss limited instead of transparency limited. By the use of the step graded-index separate-confinement heterostructure to reduce the waveguide loss, a low threshold current density of 319 A/cm/sup 2/ was measured on compressive-strained single-quantum-well broad-area lasers with a 27 mu oxide stripe width. >