We investigate the feasibility and performance of photon-number-resolved photodetection employing single-photon avalanche photodiodes (SPADs) with low dark counts. While the main idea, to split n photons into m detection modes with no more than one photon per mode, is not new, we investigate here a important variant of this situation where SPADs are side-coupled to the same waveguide rather than terminally coupled to a propagation tree. This prevents the nonideal SPAD quantum efficiency from contributing to photon loss. We propose a concrete SPAD segmented waveguide detector based on vertical directional coupler design, and characterize its performance by evaluating the purities of positive-operator-valued measurements (POVMs) in terms of SPAD number m, photon loss, and dark counts.
@article{arxiv.1708.09015,
title = {Photon-number-resolving segmented detectors based on single-photon avalanche-photodiodes},
author = {Rajveer Nehra and Chun-Hung Chang and Qianhuan Yu and Andreas Beling and Olivier Pfister},
journal= {arXiv preprint arXiv:1708.09015},
year = {2020}
}