Differential heterodyne frequency conversion at 0.4 mm wavelength
B. T. Ulrich, Rob W. van der Heijden, J. M. V. Verschueren
A Josephson‐effect differential heterodyne receiver converts a variable signal frequency fS, near a fixed local oscillator fL, to a fixed intermediate frequency fI=fS−fL−fQ, by mixing between fD=fS−fL and a voltage‐tunable variable quantum oscillation fQ=2eV/h provided by a double‐junction resistive interferometer. At fL−0.7 THz provided by a far infrared formic acid laser, with fS=fL+fD provided by a Doppler shift, power conversion efficienciesηQ from fDγfI up to 0.2 were observed. Linewidths of the quantum oscillation δfQ∠ (2kBT/πL)1/2 (2eR/h) down to ∠0.5 Hz were observed for R=3.3×10−9Ω interferometer resistance, and L∠10−9 H interferometer inductance, demonstrating an intrinsic frequency resolution of 1 in 1012 at high conversion efficiency for the technique.
AIP conference proceedings•Jan 1, 1978•0 citations