Submillimeter wave signal detection by bicrystal YBCO Josephson junctions at liquid nitrogen temperatures

The submillimeter wave signal detection has been experimentally studied for a high-T-c superconducting device, consisting of a bicrystal YBa2Cu3Ox, Josephson junction, incorporated with a log-periodic antenna. Measurements were carried out in wide range of temperatures T = 20-80 K. At relatively high temperatures T > 60 K, the thermally activated phase slippage began to predominate. At the same time, a set of clearly resolved detector response functions have been registered up to the temperatures close to the critical one. At the highest temperature T similar or equal to 80 K, where detector response has been registered, the ratio of the frequency of applied signal f similar or equal to 500 GHz to the critical frequency of Josephson junction f, has been estimated as large as f(s)/f(c) similar or equal to 40. (C) 2002 Elsevier Science B.V. All rights reserved.