# Comparative study of afterpulsing behavior and models in single photon counting avalanche photo diode detectors

## TL;DR

This study compares afterpulsing behaviors in avalanche photodiodes from different manufacturers, revealing significant differences and the presence of high-order afterpulses, which impact quantum optics applications and require individual detector calibration.

## Contribution

It provides a comparative analysis of afterpulsing in APDs from multiple manufacturers, highlighting the need for detector-specific calibration and introducing a procedure for it.

## Key findings

- Significant differences in afterpulsing behavior between detectors.
- Detection of high-order afterpulses not covered by standard models.
- Calibration procedure for individual detectors demonstrated.

## Abstract

Single-photon detectors, like Avalanche Photo Diodes (APDs), have a great importance in many fields like quantum key distribution, laser ranging, florescence microscopy, etc. Afterpulsing is a typical non ideal behavior of APDs, operated in Geiger mode, which adversely affects any application which measures the number or timing of detection events. Several conflicting studies have tried to model afterpulsing behavior and link it to fundamental semiconductor physics. Here we describe experiments we performed on at least 2 different detectors from 3 manufacturers, all commonly used in quantum optics setups. We report on the timing structure of the counts. By fitting different models to these data, we found statistically significant differences between the detectors used. Furthermore, we report on the presence of high order afterpulses which are not accounted for in any of the standard models of afterpulse behavior. This might have significant implication e.g. in quantum key distribution systems, as the modeling of the devices in use will have to be part of the security analysis for some systems. Significant differences between manufacturers and even between seemingly identical detectors of the same make and batch suggest that every individual detector needs to be calibrated. We describe a reliable procedure to perform such a calibration and present our findings on three different commercial products.