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 μm. 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.
Original language | English |
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Article number | 065016 |
Number of pages | 9 |
Journal | Superconductor Science & Technology |
Volume | 29 |
Issue number | 6 |
DOIs | |
Publication status | Published - 2016 |
Bibliographical note
Accepted Author ManuscriptKeywords
- microcavity
- nitride
- photodetectors
- single-photon detectors
- SNSPD
- superconducting-nanowire detectors
- waveguide