Abstract
We developed superconducting nanowire single-photon detectors based on tungsten silicide, which show saturated internal detection efficiency up to a wavelength of 10 μm. These detectors are promising for applications in the mid-infrared requiring sub-nanosecond timing, ultra-high gain stability, low dark counts, and high efficiency, such as chemical sensing, LIDAR, dark matter searches, and exoplanet spectroscopy.
Highlights
Efficient single-photon counting, with a detection efficiency greater than 50%, has, to date, been achieved only at wavelengths shorter than 2 μm.[1]
We developed superconducting nanowire single-photon detectors based on tungsten silicide, which show saturated internal detection efficiency up to a wavelength of 10 μm
These detectors are promising for applications in the mid-infrared requiring sub-nanosecond timing, ultra-high gain stability, low dark counts, and high efficiency, such as chemical sensing, LIDAR, dark matter searches, and exoplanet spectroscopy
Summary
Efficient single-photon counting, with a detection efficiency greater than 50%, has, to date, been achieved only at wavelengths shorter than 2 μm.[1]. Our results indicate that it may be possible to achieve high system detection efficiency in the mid-infrared with WSi SNSPDs by optimizing the absorption in the nanowires and the coupling to the active area of the detectors, as has been done at near-infrared wavelengths. The first approach is to decrease the cross-sectional area of the nanowire, making the film thinner or the nanowire narrower This results in a higher probability of a hotspot (non-superconducting domain) being generated since the energy per unit area is larger, and thermal conduction along the length of the nanowire is smaller. Using this approach, saturated internal detection efficiency has been demonstrated with NbN SNSPDs up to a wavelength of ∼3 μm using ultra-narrow 30 nm-wide nanowires.[19]. The films remain amorphous over a wide range of sputtering parameters and stoichiometries,[27] as verified by x-ray diffraction measurements for the samples presented here
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