Flux-flow-type Josephson oscillator for millimeter and submillimeter wave region. IV. Thin-film coupling

Abstract

Power emission from a flux-flow-type Josephson oscillator with a thin-film coupling method is studied experimentally. The thickness of one electrode of the oscillator is made thin enough to allow electromagnetic fields generated by the oscillator to be emitted through the thin-film electrode. Radiation power from the oscillator is detected with superconductor-insulator-superconductor detectors, which are fabricated on top of the oscillator. Experimental results show that sufficient power can be obtained from the oscillator by using the thin-film coupling method when the thickness of the electrode is comparable to the London penetration depth. The results obtained are in reasonable agreement with theoretical predictions. The thin-film coupling method will be useful when the oscillator is connected to external circuits, such as an impedance matching circuit.