Design of polarization-insensitive superconducting single photon detectors with high-index dielectrics

TL;DR

This paper presents novel cavity architectures for superconducting nanowire single-photon detectors that achieve high absorption efficiency and polarization insensitivity by using high-index dielectrics to reduce index mismatch.

Contribution

The authors introduce simple cavity designs utilizing high-refractive-index dielectrics to enable polarization-insensitive detection with efficiencies over 90% in superconducting nanowire detectors.

Findings

Achieved over 90% absorption efficiency with polarization insensitivity.

Designed cavity architectures suitable for NbTiN nanowires.

Discussed potential advantages for WSi and MoSi nanowires.

Abstract

In this paper, the design of superconducting-nanowire single-photon detectors which are insensitive to the polarization of the incident light is investigated. By using high-refractive-index dielectrics, the index mismatch between the nanowire and the surrounding media is reduced. This enhances the absorption of light with electric field vector perpendicular to the nanowire segments, which is generally hindered in this kind of detectors. Building on this principle and focusing on NbTiN nanowire devices, we present several easy-to-realize cavity architectures which allow high absorption efficiency (in excess of 90%) and polarization insensitivity simultaneously. Designs based on ultranarrow nanowires, for which the polarization sensitivity is much more marked, are also presented. Finally, we briefly discuss the specific advantages of this approach in the case of WSi or MoSi nanowires.