Photon-number resolving performance of the InGaAs/InP avalanche photodiode with short gates

By using a self-differencing circuit to achieve efficient spike cancellation for the near-infrared single-photon detector based on InGaAs/InP avalanche photodiode, we verified that shortening the gate duration enforced the detection efficiency to saturate at an increased voltage, while increasing the avalanche gain favored the discrimination of the avalanche signals caused by different photon-number states. Photon-number resolving detection was realized by measuring the weak current at the avalanche built-up. The photon-number resolving performance could be improved by shortening the gating pulse duration.