Submillimeter wave response and noise in HTS Josephson junctions

The IV curves and the direct detector response of HTS bicrystal grain-boundary Josephson junctions have been measured under submm-wave irradiation at frequencies 350-750 GHz. The Josephson oscillation spectrum has been measured using the Hilbert transformation of detection response dependence. The Josephson oscillation linewidth and corresponding value of effective noise is compared to the estimates from the de measurements of noise rounding of IV curve. To separate sources of noise the direct measurements of junction's output noise has been performed at 1.5 GHz and low frequencies 0.5-20 kHz.