  Superconducting nanowire single-photon detectors (SNSPDs) are a leading
detector type for time correlated single photon counting, especially in the
near-infrared. When operated at high count rates, SNSPDs exhibit increased
timing jitter caused by internal device properties and features of the RF
amplification chain. Variations in RF pulse height and shape lead to variations
in the latency of timing measurements. To compensate for this, we demonstrate a
calibration method that correlates delays in detection events with the time
elapsed between pulses. The increase in jitter at high rates can be largely
canceled in software by applying corrections derived from the calibration
process. We demonstrate our method with a single-pixel tungsten silicide SNSPD
and show it decreases high count rate jitter. The technique is especially
effective at removing a long tail that appears in the instrument response
function at high count rates. At a count rate of 11.4 MCounts/s we reduce the
full width at one percent maximum level (FW1%M) by 45%. The method therefore
enables certain quantum communication protocols that are rate-limited by the
(FW1%M) metric to operate almost twice as fast. \c{opyright} 2022. All rights
reserved.
