GaN-based vertical-cavity surface emitting lasers with sub-milliamp threshold and small divergence angle

Abstract

A GaN-based vertical-cavity surface emitting laser (VCSEL) structure featuring a silicon-diffusion-defined current blocking layer for lateral confinement is described. Sub-milliamp threshold currents were achieved for both 3- and 5-mu m-aperture VCSELs under continuous-wave operation at room temperature. The vertical cavity was defined by a top dielectric distributed Bragg reflector (DBR) and a bottom epitaxial DBR. The emission spectrum exhibited a single peak at 411.2 nm with a line-width of 0.4nm and a side mode suppression ratio of more than 10 dB before device packaging. The full-width-at-half-maximum divergence angle of the 3-mu m-aperture VCSEL was as small as approximately 5 degrees which is the lowest number reported. These results implied the 3-mu m-aperture VCSEL was in near single-mode operation. Published by AIP Publishing.