Optimisation of /spl lambda/=850 nm hybrid-mirror vertical-cavity surface-emitting laser with 37 /spl mu/A threshold current

摘要

A vertical-cavity surface-emitting laser (VCSEL) structure is optimised for low threshold current. The cavity comprises a GaAlAs bottom DBR with a dielectric SiO/sub 2/-Si/sub 3/N/sub 4/ output mirror on top. The asymmetrical active region consists of GaAs-QWs, emitting at 850 nm. Selective lateral oxidation is applied to the p-side AlAs layer for current confinement. With the realised structure, a record low threshold current for selectively oxidised, hybrid Ga(Al)As lasers of I/sub th/=37 /spl mu/A at an oxide-aperture diameter of O/sub ap/=4.9 /spl mu/m is achieved. The observed multimode emission spectrum is analysed using a simplified theoretical model for the transverse-mode guiding, and first experimental results of a redesigned VCSEL structure with single-mode operation at similar aperture diameters are presented.