Small efficient vertical cavity lasers with taperedoxide apertures

The authors demonstrate vertical cavity lasers utilising tapered apertures to close the active region, permitting good current confinement combined with low optical scattering losses. Because the slope efficiency remains high at small sizes, devices as small as 2 µm in diameter have wall-plug efficiencies of > 20%. By better scaling, wall-plug efficiencies of 17–25% are achieved at low output powers of 100–500 µW.