Harnessing of temporal dispersion for integrated pump filtering in spontaneous heralded single-photon generation processes

Abstract

Cointegration of heralded single-photon generation and on-chip detection requires the ability to differentiate between pump light and single photons. We explored the dispersion-induced temporal separation of optical pulses to reach this goal. Our method exploits the distinct group velocities of pump light and single photons, as well as single-photon detectors with high timing resolution. We simulate the propagation for photon pair generation by spontaneous parametric down-conversion in titanium in-diffused waveguides in lithium niobate and thin-film lithium niobate, and spontaneous four-wave mixing in silicon on insulator and silicon nitride. For the different integration platforms, we show the propagation distance required to sufficiently distinguish between pump and single photons for different timing resolutions, and demonstrate that this should be feasible with current superconducting nanowire single-photon detector technologies. Finally, we experimentally simulate our approach using the dispersion in the optical fiber.