Submillimetre and millimetre response of Josephson junctions mounted in a waveguide

R. S. Avakian, Alexander N. Vystavkin, Vladimir N. Gubankov +1 more

Koji Tsuru, Kazunori Miyahara, Minoru Suzuki

R. Blundell, K. H. Gundlach

We have extended techniques used in the development of low noise quasiparticle mixers for the 3mm and 2mm wavelength ranges to include the 1.3mm range. A double sideband receiver noise temperature of below 200K has been measured using a waveguide mounted quas-particle mixer at 223 GHz. Photon assisted quasiparticle tunneling steps have been observed at 462 GHz suggesting that the type of junction used in our quasiparticle mixers may be used for low noise mixing up to this frequency.

T. G. Blaney

The Josephson effects, which arise at a suitable junction between two pieces of superconducting material, have several applications at millimetre and submillimetre wavelengths. Devices based on the effects can be used as video detectors, harmonic mixers and frequency analysers, often with unique properties. These and other possible applications are described, and the current experimental situation using the ‘point contact’ type of junction is outlined.

T. G. Blaney, C. C. Bradley

In an extension of earlier work, the response of niobium-niobium point-contact Josephson junctions to radiation from hydrogen cyanide and deuterium cyanide lasers has been studied. Constant voltage steps corresponding to the 805, 891 and 964 GHz lines from a HCN laser have been observed as well as steps corresponding to the frequency mixtures of all these lines. In addition, subharmonic and harmonics of `mixed-frequency' steps have also been observed. The first observation of Josephson step structure corresponding to the 1540 and 1578 GHz emissions of a DCN laser is reported.

C. C. Grimes