Integrated Telecom Wavelength Heralded Single-Photon Source based on GHz gated detectors

We introduce a simple and flexible concept for a heralded - spectrally pure - single photon source. The scheme uses a probabilistic photon pair source pumped with a CW laser, whereby a rapid gating InGaAs/InP single photon avalanche diode provides a synchronous clock for the system. The low timing jitter of the detector temporally resolves, and hencespectrally filters, the heralded photons. We demonstrate the concept by combining this with a narrow-band integrated silicon nitride photon-pair source. This simple architecture is capable of heralding photons with high spectral purity in the telecom band, but could be adapted to other wavelengths and bandwidth regimes.