AC Josephson effect in high-T/sub c/ polycrystalline thin-film bridges

The effect of millimeter-wave electromagnetic radiation on the I-V curves of superconducting bridges made from polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-x/ films with a grain size of approximately 1 mu m and a critical current density of j/sub c/(4.2 K) approximately 10/sup 4/ A/cm/sup 2/ was investigated. When the bridge dimensions w*1 were decreased from 200*200 mu m/sup 2/ to 5*5 mu m/sup 2/, the effect of radiation at T<or=100 mu m) to vortex synchronization (20 mu m