Integrating superconductive and optical circuits

We have integrated on oxidized silicon wafers superconductive films and Josephson junctions along with sol-gel optical channel waveguides. The fabrication process is carried out in two steps that result to be solid and noninvasive. It is demonstrated that 660 nm light, coupled from an optical fiber into the channel sol-gel waveguide, can be directed toward superconducting tunnel junctions whose current-voltage characteristics are affected by the presence of the radiation. The response of the junction biased at various currents as a function of the optical pumping is presented and discussed according to a nonequilibrium superconductivity model.