Superconducting tunnel junctions as detectors for ultraviolet, optical, and near infrared astronomy

Astrophysics Division, Space Science Department of ESA, ESTEC, Noordwijk 2200AG, The Netherlands

Received: 22 April 1996
Accepted: 27 September 1996

Abstract

We discuss the capabilities of superconducting tunnel junctions as detectors for ultraviolet, optical, and near-infrared astronomy. Such junctions have recently been shown to allow the detection of individual optical and ultraviolet photons with an inherent spectral resolution related to the critical temperature of the absorbing superconductor. Limiting resolutions at 500 nm ranging from 5 – 40 nm (for materials with critical temperatures between 0.1 to 10 K) should be achievable. These detectors should have a high quantum efficiency ( per cent) over a very broad wavelength range from the ultraviolet to the near infrared (100 – 2000 nm). The overall efficiency is limited by reflection from the superconducting film, and should be improved significantly by appropriate anti-reflection coatings. The devices function at very high incident photon rates—with count rates of order 10 kHz or higher being feasible, and photon arrival time datation possible to microsec-level accuracy. It is realistic in the future to envisage that these devices, of a size typically , could be packaged into imaging arrays. These key characteristics imply that many areas of optical and ultraviolet astronomy could benefit significantly from their further development.