Epitaxially-grown mode-tunable InP micro-ring lasers

In the near future, technological advances driven by the Fourth Industrial Revolution will boost the demand for integrated, power-efficient miniature lasers, which are important for optical data communications and advanced sensing applications. Although top-down fabricated III-V semiconductor micro-disk and micro-ring lasers have been shown to be efficient light sources, challenges such as etching-induced sidewall roughness and poor fabrication scalability have been limiting the potential for high-density on-chip integration. Here, we demonstrate InP micro-ring lasers fabricated with a highly-scalable epitaxial growth technique. With an optimized cavity design, the optically-pumped micro-ring lasers show efficient room-temperature lasing with lasing threshold of around 50 μJ cm-2 per pulse. Remarkably, through comprehensive modelling of the micro-ring laser, we demonstrate experimentally lasing mode engineering by tuning the vertical ring height. Our work is a major step toward realizing high-density monolithic integration of III-V miniature lasers on submicron-scale optoelectronic devices.