Single-mode nanolasers based on FP-WGM hybrid cavity coupling

As an idealized light source, semiconductor nanowire (NW) lasers have been extensively studied due to its potential applications in many fields such as optoelectronics, nanophononics, optical communication, signal processing, and displays. In this letter, we proposed a novel approach to realize a single-mode nanolaser by forming an Fabry-Perot whispering gallery mode (FP-WGM) hybrid nanocavity between two cross-contact CdS NWs, i.e. x and y-NW. In our method, x-NW supports the regular FP oscillation in the axis direction while the cross section of y-NW provides a ultrasmall WGM nanocavity with a higher Q-factor and mode election which confirms the specific single mode can be excited. Experimentally, single-mode lasing emission centered at 517 nm was obtained with full width at half maximum of 0.08 nm and lasing threshold of similar to 50 kW cm-2. The suggested designing skills projected a general strategy for lasing mode regulation and single-mode realization. The single-mode low-threshold lasing strategy in coupled NWs may open a new avenue for practical applications of NW lasers and further trigger other photonic devices at a visible range.