FREQUENCY DEPENDENCE OF THE EMISSION FROM 2D ARRAY JOSEPHSON OSCILLATORS

Coherent emission from two-dimensional arrays of Josephson junctions, coupled to a detector junction through a dc blocking stripline capacitor, was detected over a frequency range from 50 to 210 GHz. A power of 0.26 pW which is larger than the 0.1 mu W expected from the RSJ model was detected in a range from 140 to 150 GHz. Frequencies where no emission was detected correspond to standing waves in the capacitor when multiples of the half-wavelength match the capacitor length. Low temperature scanning electron microscopy confinned the presence of standing waves at these frequencies, but also revealed standing waves at other frequencies indicating an impedance mismatch and a possible extension of the standing waves into the array.