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Proceedings Paper

Polar-azimuthal angle dependent efficiency of different infrared superconducting nanowire single-photon detector designs
Author(s): Mária Csete; Áron Sipos; Faraz Najafi; Karl K. Berggren
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Paper Abstract

The illumination-angle-dependent absorptance was determined for three types of superconducting-nanowire singlephoton detector (SNSPD) designs: 1. periodic bare niobium-nitride (NbN) stripes with dimensions of conventional SNSPDs, 2. the same NbN patterns integrated with ~quarter-wavelength hydrogensilsesquioxane-filled nano- cavity, 3. similar cavity-integrated structures covered by a thin gold reflector. A three-dimensional finite-element method was applied to determine the optical response and near-field distribution as a function of p-polarized light illumination orientations specified by polar-angle, φ, and azimuthal-angle, γ. The numerical results proved that the NbN absorptance might be maximized via simultaneous optimization of the polar and azimuthal illumination angles. Complementary transfer-matrix-method calculations were performed on analogous film-stacks to uncover the phenomena contributing to the appearance of extrema on the optical response of NbN-patterns in P-structure-configuration. This comparative study showed that the absorptance of bare NbN patterns is zero at the angle corresponding to total internal reflection (TIR). In cavity-integrated structures the NbN absorptance curve indicates a maximum at the same orientation due to the phase shift introduced by the quarter-wavelength HSQ layer. The reflector promotes the NbN absorptance at small polar angles, but the available absorptance is limited by attenuated TIR in polar angle-intervals, where surface modes are excited on the gold film.

Paper Details

Date Published: 16 September 2011
PDF: 8 pages
Proc. SPIE 8155, Infrared Sensors, Devices, and Applications; and Single Photon Imaging II, 81551K (16 September 2011); doi: 10.1117/12.893879
Show Author Affiliations
Mária Csete, Univ. of Szeged (Hungary)
Massachusetts Institute of Technology (United States)
Áron Sipos, Univ. of Szeged (Hungary)
Faraz Najafi, Massachusetts Institute of Technology (United States)
Karl K. Berggren, Massachusetts Institute of Technology (United States)

Published in SPIE Proceedings Vol. 8155:
Infrared Sensors, Devices, and Applications; and Single Photon Imaging II
Manijeh Razeghi; Paul D. LeVan; Ashok K. Sood; Priyalal S. Wijewarnasuriya, Editor(s)

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