Selectively etched undercut apertures in AlAsSb-based VCSELs

Apertures were formed in single-growth, AsSb-based, long-wavelength (1.55 μm) vertical-cavity surface-emitting lasers by laterally etching the active region. The materials contrast between the AlAsSb-based mirrors and the AlInGaAs-based active region leads to a high selectivity for the etch, allowing long apertures to be formed with minimal etching of the mirrors. Lasers showing reduced threshold currents and increased efficiencies were demonstrated using these apertures.