Abstract: Quantum key distribution (QKD) achieves information-theoretic security based on quantum mechanics principles, where single-photon detectors (SPDs) serve as critical components. This study focuses on the sinusoidal gated SPDs widely used in high-speed QKD systems. We investigate the mechanisms underlying the rising-edge jitter in detection signals, identifying contributions from factors such as the temporal width of injected optical pulses, avalanche generation processes, avalanche signal extraction, and pulse discrimination. To address the issue of excessive jitter-induced bit errors, we propose a retiming scheme that utilizes coincidence signals synchronized with the sinusoidal gating signal. This approach effectively suppresses detection signal jitter and reduces the after-pulse probability of the detector. Experimental validation using a high-precision time-to-digital converter (TDC) demonstrates a significant reduction in the rising-edge jitter distribution after applying the suppression scheme. The proposed method features clear principles and straightforward engineering implementation, avoiding direct interference with the detector’s operational processes. The designed high-speed sinusoidal gated InGaAs/InP SPD operates at 1.25GHz, achieving a remarkable reduction in after-pulse probability from 10.7% (without jitter suppression) to 0.72%, thereby enhancing the overall performance of QKD systems.

Key words: single-photon detector, high-speed sinusoidal gating, avalanche signal extraction, detection signal jitter suppression.