(a) Schematics of the WZ based InP NW, facet-rotated InP core-shell NW, and InGaAs/InP MQW NW, respectively. (b) 30° tilted SEM image of the NW array grown on InP(111)A substrate. (c) STEM-HAADF image of the lateral cross-section of an InGaAs/InP QW NW. The dashed blue line indicates the expected position of WZ InP NW core which is covered with the 30° rotated InP shell and MQW structure. (d) STEM-HAADF image taken along [112] zone axis from the vertical cross-section of NW top segment.

(a) Emission spectra at different pump fluences of a single standing NW. Inset shows the corresponding normalized spectral intensity map. (b) Telecom-band lasing spectra from NWs with different indium compositions in the QWs at room temperature under a pump fluence of 1.3 Pth. (c-e) Optical images from the NW array before (c), and after (d) lasing threshold. (e) Image on (d) under an attenuated pump fluence.