Near-field induced FIR Josephson-detection by c-axis-oriented YBa₂Cu₃O₇-delta-films

A novel approach to intrinsic Josephson-detection of far infrared radiation is reported utilizing near-zone field effects at electric contacts on c-axis oriented YBa_2Cu_3O_7-delta films. While only a bolometric signal was observed focusing the radiation far off the contacts on c-axis normal films, irradiating the edge of contacts yielded an almost wavelength independent fast signal showing the characteristic intensity dependence of Josephson-detection. The signal is attributed to a c-axis parallel component of the electric radiation field being generated in the near-zone field of diffraction at the metallic contact structures.