Purcell‐Enhanced Single‐Photon Emission in the Telecom C‐Band

Purcell‐enhanced quantum dot single‐photon emission in the telecom C‐band from InAs quantum dots inside circular Bragg grating cavities is shown. The InAs quantum dots are grown by means of molecular beam epitaxy on an InP substrate and are embedded into a quaternary In0.53Al0.23Ga0.24As membrane structure. In a post‐growth flip‐chip process with subsequent substrate removal and electron beam‐lithography, circular Bragg grating (“bullseye”) resonators are defined. Micro‐photoluminescence studies of the devices at cryogenic temperatures of T=5$T = 5$ K reveal individual quantum dot emission lines into a pronounced cavity mode. Time‐correlated single‐photon counting measurements under above‐band gap excitation yield Purcell‐enhanced excitonic decay times of τ=(180±3)$\tau =(180\pm 3)$ ps corresponding to a Purcell factor of FP=(6.7±0.6)${F}_{P}=(6.7\pm 0.6)$. Pronounced photon antibunching with a background limited g(2)(0)=(0.057±0.004)${g}^{(2)}(0)=(0.057\pm 0.004)$ is observed, which demonstrates that the light originated mostly from one single quantum dot. On‐demand single‐photon sources are a key element of photonic quantum communication and quantum computing. Here, Purcell‐enhanced single‐photon emission in the telecom C‐band from InAs quantum dots embedded into circular Bragg grating optical micro‐resonators is shown.