Design of broadband high-efficiency superconducting-nanowire single photon detectors. (6th May 2016)

• Record Type: Journal Article
• Authors: Redaelli, L; Bulgarini, G; Dobrovolskiy, S; Dorenbos, S N; Zwiller, V; Monroy, E; Gérard, J M
• Is Part Of: Superconductor science & technology. Volume 29:Number 6(2016:Jun.)
• Publication Date: 2016-05-06
• Subjects: photodetectors -- single-photon detectors -- superconducting-nanowire detectors -- waveguide -- microcavity -- SNSPD -- nitride; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/0953-2048/29/6/065016
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: In this paper several designs to maximize the absorption efficiency of superconducting-nanowire single-photon detectors are investigated. Using a simple optical cavity consisting of a gold mirror and a SiO2 layer, the absorption efficiency can be boosted to over 97%: this result is confirmed experimentally by the realization of an NbTiN-based detector having an overall system detection efficiency of 85% at 1.31 μ m. Calculations show that by sandwiching the nanowire between two dielectric Bragg reflectors, unity absorption (>99.9%) could be reached at the peak wavelength for optimized structures. To achieve broadband high efficiency, a different approach is considered: a waveguide-coupled detector. The calculations performed in this work show that, by correctly dimensioning the waveguide and the nanowire, polarization-insensitive detectors absorbing more than 95% of the injected photons over a wavelength range of several hundred nm can be designed. We propose a detector design making use of GaN/AlN waveguides, since these materials allow lattice-matched epitaxial deposition of Nb(Ti)N films and are transparent on a very wide wavelength range.