Electrically pumped single-mode microlasers with omnidirectional radiation for optical broadcasting communication

Semiconductor whispering gallery mode (WGM)-visible microlasers are promising compact, on-chip light sources for high-speed visible-light communication due to their small footprints, high Q factors, and in-plane emission. However, achieving fabrication robustness, precise mode selection, narrow linewidths, and low thresholds for WGM-visible microlasers remains challenging. Here, we report a scalable strategy to fabricate continuous-wave, electrically pumped WGM blue microlasers based on III-nitride semiconductors with low threshold current densities and high slope efficiencies across diverse diameters from 10 to 160 micrometers. This high performance was achieved through effective vertical optical confinement by the waveguide structures and minimal sidewall scattering from atomically smooth surfaces. We further converted the laser cavity from a microdisk to a microring, which suppresses high-order WGMs and allows for single-mode operation with a high Q factor of 17,066. The omnidirectional in-plane radiation of WGM microlasers demonstrates angle-independent, high-modulation bandwidths, enabling synchronous broadcasting communication with high data transmission rates.