190-GHZ RADIATION FROM A QUASI-OPTICAL JOSEPHSON-JUNCTION ARRAY

At 190 GHz, 0.36 mu W has been detected from an 11x58 array of niobium Josephson junctions. The power is radiated directly into free space a bove the surface of the two-dimensional array of junctions. Detection is made by a commercial bolometer outside the array cryostat. The junc tions in the array are closely spaced in the y-dimension, but spaced b y more than one-half wavelength in the x-direction. This asymmetry res ults in mutual phase-locking between adjacent junctions suitable for t he production of y-polarized radiation, The resonance and asymmetry al so result in a reasonable impedance match between the Josephson juncti ons and the free-space radiation mode.