Heterostructure and Q-factor engineering for low-threshold and persistent nanowire lasing

Semiconductor nanowire lasers are a crucial component for on-chip integrated optoelectronics. However, silicon-integrated, room-temperature, continuously-operating and electrically-pumped nanowire lasers have not yet been demonstrated. In this work, a method to achieve low-threshold quasi-four-level lasing using indirect-to-direct band scattering is shown. This is enabled by the use of a high-Q cavity, and—using a time-gated interferometry technique—the end-facet reflectivity is directly measured for the first time.