STAGE Terahertz imaging using a high-Tc superconducting Josephson junction detector

THz electromagnetic waves (300- 10 000 GHz) are recognized as a potential tool in a broad array of applications provided their unique properties. For instance, THz waves allow high transmission through a wide range of light materials such as plastics, fog, tissues, clothes, walls and papers. They have a strong sensitivity to water content and a spectroscopic response to materials enabling identification of substances, such as pollutants, chemicals, explosives, odd biological samples. Since their frequency is very high, THz waves can be used for large data rate communications. Combined with the capability to "see through", it is possible to make "hyper-spectral" imaging of a hidden scene. Despite huge prospects, the THz region of the electromagnetic spectrum has, so far, not been exploited fully due to limitations of the available source and detector technology. Detectors with a high sensitivity, wide-band frequency coverage are required for THz imaging. Superconducting devices are excellent candidates due to their extremely low noise, power consumption and high frequency operation (up to 7 THz).
The aim of this work will consist in making a practical and compact THz imager based on a high-Tc superconducting Josephson junction detector. Our team at ESPCI-Paris has developed a powerful technique to structures High-Temperature Superconducting films (YBCO) at the nanoscale combining advanced electron beam lithography with ion irradiation technique. During this project will be study the response of a Josephson junction illuminated by a THz signal, in a Cryogen-free
Cryostat system. We will show that our junction is suitable to make a THz image of a hidden object.