Infrared Superconducting Single-Photon Detectors

Abstract : This report culminates a contract tasking Heriot-Watt University to explore design and fabrication of superconducting nanowire single photon detectors (SNSPDs). Using Heriot-Watt s electron beam lithography system, Dr. Hadfield s group realized small microstrip devices, the next iteration of which may narrow the line width to below 100 nm, entering the single-photon detection regime in the infrared region. Exploring the design of single-photon camera devices, the group manufactured a prototype SNSPD device with a single wire of varying thickness; by exploiting timing measurements, they were able to determine if light was focused on one end of the camera device or the other, helping localize the impact of photons. To maximize the probability of mid-infrared photon absorption triggering a SNSPD, Dr. Hadfield s group employed EOARD funding to explore low energy gap superconducting materials which require sub Kelvin operating temperatures, which should enable operation of fibre-coupled and microscope-coupled superconducting devices (at the time of the final report, the cryostat is not yet complete; completion estimated in early 2013). During the investigative period the PI publish 7 original papers in refereed journals and completed the first major review on this field and delivered several webcasts on infrared counting technologies, and EOARD funding enabled three conference presentations. PI has accepted the position of Professor of Photonics at University of Glasgow, UK, and his future work will occur there, with a nanofabrication facility and will explore superconducting detectors with integrated waveguide circuits and novel deposition techniques.