Superconducting infrared detector arrays with integrated processing circuitry
Thin-film Josephson junctions may be used as infrared detectors that function by a thermal sensing mechanism. In addition to the potential for high sensitivity to a broad range of optical wavelengths, they are ideally suited for integration with superconducting electronics on a single wafer. To develop these arrays, work was directed along two avenues: (1) maximizing the sensitivity of individual Josephson junction detector/SQUID amplifier units, and (2) development of superconducting on-chip processing circuitry-multiplexers and analog-to-digital converters. Superconducting detector/amplifier circuits were designed for low-noise performance. Amplification in these chips has been successfully demonstrated. Square 8*8 arrays integrated with various elements of superconducting processing circuitry have also been fabricated and tested. These use niobium Josephson junctions and 65 mu m*85 mu m absorber areas, and have been tested at 4.2 K. One such array includes circuitry for multiplexing all detectors, and was used successfully to form an image that was presented in real time on a computer terminal display. The output of a single detector was also used to drive a superconducting analog-to-digital converter.