Detection Mechanism in SNSPD: Numerical Results of a Conceptually Simple, Yet Powerful Detection Model

TL;DR

This paper reviews and improves a numerical model for SNSPD photon detection, enabling more accurate current distribution calculations and revealing different detection mechanisms in WSi compared to NbN.

Contribution

The paper introduces an improved algorithm for modeling SNSPD detection, allowing detailed analysis of inhomogeneous quasi-particle densities and detector responses.

Findings

Enhanced accuracy in current distribution calculations.

Different detection mechanisms identified in WSi compared to NbN.

Analysis of off-center and two-photon absorption effects.

Abstract

In a recent publication we have proposed a numerical model that describes the detection process of optical photons in superconducting nanowire single-photon detectors (SNSPD). Here, we review this model and present a significant improvement that allows us to calculate more accurate current distributions for the inhomogeneous quasi-particle densities occurring after photon absorption. With this new algorithm we explore the detector response in standard NbN SNSPD for photons absorbed off-center and for 2-photon processes. We also discuss the outstanding performance of SNSPD based on WSi. Our numerical results indicate a different detection mechanism in WSi than in NbN or similar materials.