Parametric amplification of electromagnetic waves produced by a flux-flow-oscillator made of YBa2Cu3O7−δ Josephson junction arrays

Abstract

We observe parametric amplification of electromagnetic (EM) waves produced by a flux-flow oscillator made of YBa2Cu3O7−δ Josephson junctions arrays coupled to the resonant modes of a millimeter wave Fabry–Pérot resonator at a pump frequency fP = 45 GHz. For temperatures in the range (30–45) K, the frequency fS of the EM signal to be amplified could be tuned continuously in the range (1–25) GHz by an applied B-field induced flux Φ with a one-flux-quantum Φ0 periodicity. Consequently, we measured a significant parametric gain that is almost frequency independent, with a maximum of (8–10.4) dB reached at 40 K. For temperatures in the range (14–30) K, the magnetic field tunability of fS is gradually suppressed to a minimum of (1–5) GHz range where a parametric gain between 5 and 6 dB was measured. With an appropriate adjustment of design/fabrication parameters, our results suggest that the development of tunable MW generators/detectors as well as parametric amplifiers made of high transition temperature superconductors and operating in a wide range of temperatures (10 mK–77 K) is a reasonable and appealing possibility.