High emission rate from a Purcell-enhanced, triggered source of pure single photons in the telecom C-band

Several emission features mark semiconductor quantum dots as promising non-classical light sources for prospective quantum implementations. For long-distance transmission [1] and Si-based on-chip processing[2, 3], the possibility to match the telecom C-band [4] stands out, while source brightness and high single-photon purity are key features in virtually any quantum implementation [5, 6]. Here we present an InAs/InGaAs/GaAs quantum dot emitting in the telecom C-band coupled to a circular Bragg grating. The Purcell enhancement of the emission enables a simultaneously high brightness with a fiber-coupled single-photon count rate of 13.9MHz for an excitation repetition rate of 228MHz (first-lens collection efficiency ca. 17% for NA = 0.6), while maintaining a low multi-photon contribution of g(2)(0) = 0.0052. Moreover, the compatibility with temperatures of up to 40K attainable with compact cryo coolers, further underlines the suitability for out-of-the-lab implementations.