Efficient Single Photon Detection from 500 nm to 5 μm Wavelength

We report on superconducting nanowire single photon detectors (SNSPDs) based on 30 nm wide nanowires with detection efficiency eta similar to 2.6-5.5% in the wavelength range lambda = 0.5-5 mu m. We compared the sensitivity of 30 rim wide SNSPDs with the sensitivity of SNSPDs based on wider (85 and 50 nm wide) nanowires for lambda = 0.5-5 mu m. The detection efficiency of the detectors based on the wider nanowires became negligible at shorter wavelengths than the 30 nm wide SNSPDs. Our 30 nm wide SNSPDs showed 2 orders of magnitude higher detection efficiency (eta similar to 2%) up to longer wavelength (lambda = 5 mu m) than previously reported. On the basis of our simulations, we expect that by changing the optical coupling scheme and by integrating the detectors in an optical cavity, the detection efficiency of our detectors could be increased by a factor of similar to 6.