MILLIMETER-WAVE HILBERT-TRANSFORM SPECTROSCOPY WITH HIGH-T-C JOSEPHSON-JUNCTIONS

The application of Hilbert-transform spectroscopy for the measurement of high-harmonic content of the radiation from a frequency multiplier has been demonstrated in the spectral range from 60 to 450 GHz. YBa2Cu 3O7-x grain-boundary Josephson junctions made on (110) NdGaO3 bicrysta l substrates have been used in these experiments. The internal Josephs on radiation of the junctions reveals a Lorentzian shape due to therma l noise broadening. The possibility to obtain a spectral resolution as low as 280 MHz (similar to 0.01 cm(-1)) has been shown with a Josephs on junction operating at liquid-nitrogen temperature. (C) 1996 America n Institute of Physics.