Current-injection spiral-shaped microcavity disk laser diodes with unidirectional emission

Abstract

A spiral-shaped microcavity heterojunction laser diode fabricated with InGaN multiple quantum wells is demonstrated to operate under current injection conditions and emit unidirectionally. Room-temperature laser operation was achieved for microcavity disk radii ranging from 50 to 350 μm and threshold current densities as low as 4.6 kA/cm2. Unidirectional laser emission is clearly revealed in the far-field pattern with the lateral divergence angle ranging from 60° to 75°. Output power of more than 25 mW was obtained for emission wavelengths near 400 nm.