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.
A high-T c superconducting (HTS) broadband Josephson detector has been developed and applied to millimetre wave (mm-wave) and terahertz (THz) imaging. The detector is based on a YBa 2 Cu 3 O 7-x (YBCO) step-edge Josephson junction, which is coupled to a thin-film log-periodic antenna, designed for operation at 200-600 GHz, and a hemispheric silicon lens. The junction parameters have been optimised to achieve a high I c R n value so that the detector responds well to the specified frequencies at liquid nitrogen temperature (77 K). Images at ∼200 GHz and ∼600 GHz were acquired with the same detector; each demonstrated their unique properties. The results demonstrate the potential of achieving a cheaper, compact and portable multi-spectral imager based on a HTS detector.
We present a method for estimating the point spread function of a terahertz imaging system designed to operate in reflection mode. The method is based on imaging phantoms with known geometry, which have patterns with sharp edges at all orientations. The point spread functions are obtained by a deconvolution technique in the Fourier domain. We validate our results by using the estimated point spread functions to deblur several images of natural scenes and by direct comparison with a point source response. The estimations turn out to be robust and produce consistent deblurring quality over the entire depth of the focal region of the imaging system.
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