1.55-mu m InP-lattice-matched VCSELs with AlGaAsSb-AlAsSb DBRs

In this paper, we review the design, fabrication, and characterization of 1 .55-mum lattice-matched vertical-cavity surface-emitting lasers, operating continuous wave up to 88 degreesC. For one embodiment, the threshold curren t is 800 muA, the differential quantum efficiency is 23%, and the maximum o utput power is more than 1 mW at 20 degreesC and 110 muW at 80 degreesC. Th e basic structure consists of AtAsSb-AlGaAsSb mirrors, which provide both h igh reflectivity and an InP-lattice-matched structure. The quaternary mirro rs have poor electrical and thermal conductivities, which can raise the dev ice temperature. However, a double-intracavity-contacted structure along wi th thick n-type InP cladding layers circumvents these drawbacks and finally leads to an excellent performance. The measured voltage and thermal impeda nces are much lower for the intracavity-contacted device than an air-post s tructure in which current is injected through the Sb-based quaternary mirro r. The structure utilizes an undercut aperture for current and optical conf inement. The aperture reduces scattering loss at the etched mirror and cont ributes to high differential efficiency and low threshold current density.