Enhancing Detection Efficiency by Applying an Optical Cavity Structure in a Superconducting Nanowire Single-Photon Detector

Shigehito MIKI  Taro YAMASHITA  Mikio FUJIWARA  Masahide SASAKI  Zhen WANG 

Publication
IEICE TRANSACTIONS on Electronics  Vol.E94-C  No.3  pp.260-265
Publication Date: 2011/03/01
Online ISSN: 1745-1353
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Superconducting Signal Processing Technologies)
Category: INVITED
Keyword: 
single photon detector,  superconducting nanowire,  quantum information and communications,  NbN thin films, 

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Summary: 
We report on the enhancement of system detection efficiency in a superconducting nanowire single-photon detector (SNSPD) by applying the optical cavity structure. The nanowire was made using 4-nm-thick NbN thin films and covered with an SiO cavity and Au mirror designed for 1300-1600 nm wavelengths. The device is mounted into fiber-coupled packages, and installed in a practical multichannel system based on GM cryocoolers. System detection efficiency depends on the absorptance of cavity structure, and reached 28% and 40% at 1550 nm and 1310 nm wavelengths, respectively. These values were considerably higher than an SNSPD without optical cavity.