Terahertz and Millimetre Wave Imaging with a Broadband Josephson Detector Working above 77 K

Abstract

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.

Terahertz detection with a high temperature superconducting Josephson heterodyne oscillator

“…J. C. Macfarlane (1) , J. Du (1) , and A. D. Hellicar (2) The heterodyne Josephson detector was fabricated using the CSIRO HTS YBa 2 Cu 3 O 7-x step-edge Josephson junction technology [5,6]. The operation principle and the fabrication details of the R-SQUID can be found in refs.…”

“…MAGING at terahertz (THz) frequencies using hightemperature superconducting (HTS) step-edge Josephson detectors has been demonstrated recently [1,2]. The next step will be to achieve fast, real-time images, which will require progress to be made towards the use of multi-pixel detector arrays.…”

HTS Josephson junction devices for microwave and terahertz applications

“…We have recently developed HTS step-edge Josephson junction THz detector and demonstrated THz imaging [18][19][20][21]. We optimize our step-edge Josephson junctions to achieve a maximum response to a signal frequency of 0.2 -0.6 THz for operating temperatures at 77 K [19][20][21].…”

“…We optimize our step-edge Josephson junctions to achieve a maximum response to a signal frequency of 0.2 -0.6 THz for operating temperatures at 77 K [19][20][21]. However, a typical image size of 100 × 100 or 10,000 pixels takes ~ 20 minutes to obtain using a single HTS JJ detector.…”

“…Earlier reported results were obtained with the detector cooled in a cryostat filled with liquid helium [18] or liquid nitrogen [19][20][21]. We have since integrated the HTS detector and detector array in a pulse-tube cryocooler as shown in Fig 10. The aim is to develop a cryogen-free THz imaging system for industrial acceptance.…”