Enhanced radiation-loss-based radial-waveguide-coupled electrically pumped microresonator lasers with single-directional output

A novel enhanced radiation-loss (ERL)-based radial waveguide coupling mechanism for microresonator lasers is experimentally demonstrated for the first time, to the best of our knowledge, resulting in single-directional output from the lasers. A 20 μm diameter InGaAsP/InP electrically pumped microresonator laser in the form of a microcylinder resonator integrated with a transparent ERL radial output coupler is designed and fabricated. Measurement shows a low 1.5 mA lasing threshold and a relatively high output power of >0.4 mW.