MILLIMETER WAVE GENERATION BY FLUXON OSCILLATIONS IN A JOSEPHSON JUNCTION

A small‐area Josephson tunnel junction is pumped by the radiation emitted by a long Josephson junction dc biased on a zero‐field singularity. Josephson constant voltage steps are observed in the current‐voltage characteristic of the small junction at voltages of ±150 μV corresponding to the fundamental frequency of emission of the oscillator. The radiation also gives rise to quasiparticle steps around the gap‐sum voltage of the small junction. From the measured current amplitude of the steps we estimate that the maximum power coupled to the small junction is about 90 nW.