An InGaAs/InP single-photon detector (SPD) typically operates in gated mode, but the capacitive response of a single-photon avalanche diode introduces spike noise, obscuring the avalanche signal. Most avalanche signal discrimination schemes cannot completely eliminate spike noise, resulting in residual noise. Limited by residual noise, these schemes have large noise and a limited frequency tuning range. However, for applications like quantum key distribution and laser ranging, a low noise, frequency-tunable InGaAs/InP SPD is crucial for enhancing system performance. Here, we propose a (residual noise assisted) discrimination method that aligns the maximum amplitude of the avalanche signal with the peak of the residual noise. This method turns the residual noise from adversity into an advantage for signal discrimination. With this method, we achieve tunable gating frequency from DC to 1 GHz. Additionally, this method enables the discrimination of weak avalanche signals, allowing effective single-photon detection at low avalanche gain. Across the entire tuning range, at a 20% detection efficiency, the dark count rate is approximately 5.0×10−7 per gate, and the afterpulse probability is less than 1.0%, significantly lower than in previous experiments. The proposed SPD exhibits low noise and a wide tunable gating frequency range, providing a reliable foundation for various applications.
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