Picosecond superconducting single-photon optical detector
Abstract
We experimentally demonstrate a supercurrent-assisted, hotspot-formation mechanism for ultrafast detection and counting of visible and infrared photons. A photon-induced hotspot leads to a temporary formation of a resistive barrier across the superconducting sensor strip and results in an easily measurable voltage pulse. Subsequent hotspot healing in ∼30 ps time frame, restores the superconductivity (zero-voltage state), and the detector is ready to register another photon. Our device consists of an ultrathin, very narrow NbN strip, maintained at 4.2 K and current-biased close to the critical current. It exhibits an experimentally measured quantum efficiency of ∼20% for 0.81 μm wavelength photons and negligible dark counts.
- Publication:
-
Applied Physics Letters
- Pub Date:
- August 2001
- DOI:
- 10.1063/1.1388868
- Bibcode:
- 2001ApPhL..79..705G
- Keywords:
-
- 85.25.Oj;
- 85.60.Gz;
- 85.25.Pb;
- 74.70.Ad;
- 74.76.Db;
- 06.60.Jn;
- 74.25.Gz;
- Superconducting optical X-ray and gamma-ray detectors;
- Photodetectors;
- Superconducting infrared submillimeter and millimeter wave detectors;
- Metals;
- alloys and binary compounds;
- High-speed techniques;
- Optical properties