A high-T c superconducting (HTS) detector based on a YBa 2 Cu 3 O 7−x (YBCO) step-edge Josephson junction has been developed and applied to terahertz (THz) detection. The detector was coupled to a ring-slot antenna designed for operation at 600 GHz, and used for THz imaging. The results suggest that the characteristic voltage and frequency of our HTS step-edge junctions can be readily optimized for the chosen THz frequency range at easily achievable temperatures. The images also clearly demonstrate some of the unique properties of THz radiation, including the sensitivity to water content and the ability to penetrate packaging materials.
Terahertz (THz) technology is receiving increasing attention around the
world due to its important potential in many application areas. Novel
compact solid-state sources and detectors are being sought for THz radiation
and detection. We report the realization of a THz imager based on a high-
Tc
superconducting (HTS) Josephson detector working above liquid nitrogen temperature (77 K). The detector,
made of a YBa2Cu3O7−x
(YBCO) step-edge Josephson junction, is coupled to a thin-film ring-slot antenna and a
hemispheric silicon lens. Images of high visual quality are obtained which demonstrate
unique properties of THz radiation such as the sensitivity to water content and the
ability to penetrate packaging materials. The results should stimulate further
research leading to the development of a HTS superconducting THz imaging system.
Since December 1992, CSIRO and BHP have been field trialing rf HTS SQUID magnetometers for mineral prospecting applications. Ten field trials in widely varying environments (from -16°C to +4OoC ambient temperatures) in mostly remote locations saw the development of a system which can be operated in many configurations including ground based and airborne Transient ElectroMagnetics (TEM). The magnetometer system has been developed to a point where, at late times in TEM applications, the SQUID system has a higher signal-to-noise level than the competing traditional coil technology. In some trials, a SQUID magnetometer detected anomalies at later times than were observed with the coil system, indicating an enhanced ability to detect highly conductive targets. This paper reviews development of our 3-axis SQUID magnetometer. SQUID systems as B field sensors have advantages over coils which are dB/dt type sensors. We will discuss the importance of these advantages for mineral prospecting in regions with a conducting soil cover or overburden typical of the Australian landscape.
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