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

We observe parametric amplification of electromagnetic (EM) waves produced by a flux-flow oscillator made of YBaCuO Josephson junctions arrays coupled to the resonant modes of a millimeter wave Fabry-Perot resonator at a pump frequency fP=45 GHz. 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 with a one-flux-quantum periodicity. For all frequencies fS in the range (1-25) GHz we measured a significant parametric gain for operation temperatures between 30K and 45 K, with a maximum of (8-10.4) dB reached at 40K. Our results are very promising towards 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 (20 mK-77K).