### 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.

Original language | English |
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Title of host publication | Proceedings of SPIE - The International Society for Optical Engineering |

Volume | 8155 |

DOIs | |

Publication status | Published - 2011 |

Event | Infrared Sensors, Devices, and Applications; and Single Photon Imaging II - San Diego, CA, United States Duration: Aug 22 2011 → Aug 25 2011 |

### Other

Other | Infrared Sensors, Devices, and Applications; and Single Photon Imaging II |
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Country | United States |

City | San Diego, CA |

Period | 8/22/11 → 8/25/11 |

### Fingerprint

### Keywords

- dual-angle dependence
- integrated nano-cavity
- optimized efficiency
- reflector
- SNSPD

### ASJC Scopus subject areas

- Applied Mathematics
- Computer Science Applications
- Electrical and Electronic Engineering
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics

### Cite this

*Proceedings of SPIE - The International Society for Optical Engineering*(Vol. 8155). [81551K] https://doi.org/10.1117/12.893879

**Polar-azimuthal angle dependent efficiency of different infrared superconducting nanowire single-photon detector designs.** / Csete, M.; Sipos, Áron; Najafi, Faraz; Berggren, Karl K.

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

*Proceedings of SPIE - The International Society for Optical Engineering.*vol. 8155, 81551K, Infrared Sensors, Devices, and Applications; and Single Photon Imaging II, San Diego, CA, United States, 8/22/11. https://doi.org/10.1117/12.893879

}

TY - GEN

T1 - Polar-azimuthal angle dependent efficiency of different infrared superconducting nanowire single-photon detector designs

AU - Csete, M.

AU - Sipos, Áron

AU - Najafi, Faraz

AU - Berggren, Karl K.

PY - 2011

Y1 - 2011

N2 - 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.

AB - 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.

KW - dual-angle dependence

KW - integrated nano-cavity

KW - optimized efficiency

KW - reflector

KW - SNSPD

UR - http://www.scopus.com/inward/record.url?scp=80053555339&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=80053555339&partnerID=8YFLogxK

U2 - 10.1117/12.893879

DO - 10.1117/12.893879

M3 - Conference contribution

SN - 9780819487650

VL - 8155

BT - Proceedings of SPIE - The International Society for Optical Engineering

ER -