COUPLING OF TERAHERTZ RADIATION TO A HIGH-T-C SUPERCONDUCTING HOT-ELECTRON BOLOMETER MIXER

We report on efficient coupling of THz radiation to a high-T-c superco nducting hot electron bolometer that is suitable for heterodyne detect ion. Our quasi-optical system consisted of a planar self-complementary spiral antenna on a dielectric substrate clamped to an extended hyper hemispherical lens. The antenna was integrated into a co-planar line f or broadband intermediate frequency matching. Measurements in the homo dyne regime at a frequency of 2.5 THz showed a radiation pattern with a beam width of 1 degrees and a coupling efficiency of approximate to 0.1. We measured, at an intermediate frequency of 1.5 GHz, an output n oise temperature of approximate to 160 K and estimated for the device, operated in the heterodyne regime, a system noise temperature of appr oximate to 3X10(5) K. We also discuss possibilities of significant imp rovement of the sensitivity. (C) 1996 American Institute of Physics.