Observation of a voltage-tunable sub-mm wave response from a YBCO Josephson device, operating in self-pumping mode

Abstract

The first experimental data are presented on the observation of a response of a noise signal applied to a tunable-by-voltage high-TC Josephson mixer operating in a self-pumping mode within the frequency band of f = 750–970 GHz at ambient temperature T = 12.5 K. The mixer device was a thin-film YBaCuO bicrystal Josephson junction coupled with the electrodes patterned in log-periodic antenna. Experimental junctions exhibit RSJ-like I–V characteristics with a product of ICRN ≈ 2 mV (IC is the critical current and RN is the normal state resistance). Down-converted signal response was examined at an intermediate frequency band within 1–2 GHz by means of the Fourier transform spectroscopy technique. Evaluated from Fourier transform spectrograms clear double-side band mixer response functions were registered at any of the fixed bias voltages in the range of V = 1.65–2.1 mV.