A minimalist self-differencing gating scheme for dead-time-free single-photon avalanche diodes at high repetition rate

Gated quenched Single-Photon Avalanche Diode (SPAD) detectors are widely used in quantum communication and quantum computing setups employing high-repetition-rate lasers. Here, we present a novel scheme for high-repetition-rate (100 MHz) sine-wave gated SPADs, based on the self-differencing technique, which significantly simplifies previous designs while offering additional advantages. These include straightforward implementation, more precise control of the SPAD biasing, and an improved signal-to-noise ratio. We implemented this approach using an Indium Gallium Arsenide avalanche photodiode and characterized it experimentally with 100 MHz attenuated laser pulses, measuring quantum efficiency, dark count rate, and afterpulsing behavior. Importantly, we demonstrate that the detector recovers full quantum efficiency in less than one pulse-repetition period after a detection event, enabling continuous operation at 100 MHz.