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

Continuous room temperature nanowire lasing from silicon-integrated optoelectronic elements requires careful optimisation of both the lasing cavity Q-factor and population inversion conditions.We apply time-gated optical interferometry to the lasing emission from high-quality GaAsP/GaAs quantum well nanowire laser structures,revealing high Q-factors of 1250±90 corresponding to end-facet reflectivities of R=0.73±0.02.By using optimised direct-indirect band alignment in the active region,we demonstrate a well-refilling mechanism providing a quasifour-level system leading to multi-nanosecond lasing and record low room temperature lasing thresholds(~6μJ cm^(−2) pulse−1)for Ⅲ-Ⅴ nanowire lasers.Our findings demonstrate a highly promising new route towards continuously operating silicon-integrated nanolaser elements.