Investigations of afterpulsing and detection efficiency recovery in superconducting nanowire single-photon detectors

TL;DR

This paper investigates afterpulsing phenomena and detection efficiency recovery in superconducting nanowire single-photon detectors, revealing amplifier influence on afterpulsing and characterizing recovery dynamics.

Contribution

It identifies the amplifier's role in afterpulsing and provides detailed analysis of detection efficiency recovery in SNSPDs.

Findings

Afterpulsing occurs around 180 ns post-detection for both real and dark counts.

Using a different amplifier reduces or eliminates afterpulsing.

Detection efficiency temporarily increases during SNSPD recovery due to bias perturbations.

Abstract

We report on the observation of a non-uniform dark count rate in Superconducting Nanowire Single Photon Detectors (SNSPDs), specifically focusing on an afterpulsing effect present when the SNSPD is operated at a high bias current regime. The afterpulsing exists for real detection events (triggered by input photons) as well as for dark counts (no laser input). In our standard set-up, the afterpulsing is most likely to occur at around 180 ns following a detection event, for both real counts and dark counts. We characterize the afterpulsing behavior and speculate that it is not due to the SNSPD itself but rather the amplifiers used to boost the electrical output signal from the SNSPD. We show that the afterpulsing indeed disappears when we use a different amplifier with a better low frequency response. We also examine the short-lived enhancement of detection efficiency during the recovery of the SNSPD due to temporary perturbation of the bias and grounding conditions.