MECHANISMS OF OPTICAL-RESPONSE IN SUPERCONDUCTING YBA2CU3O7-DELTA THIN-FILMS AND GRAIN-BOUNDARY WEAK LINKS

The optical response of single grain-boundary weak links in supercondu cting YBCO thin films has been, investigated. At temperatures well bel ow the transition temperature, the; grain boundary exhibits an optical response which is qualitatively different from transition edge respon se. Using a resistively shunted-junction model for the grain-boundary weak link, we find that the optical response below the transition temp erature can be described by radiation induced thermal modulation of th e critical currents of the weak links. The dependence on the bias curr ent and the temperature distinguishes the weak-link optical response f rom the transition edge optical response. We discuss novel aspects of a potential radiation detector based on grain-boundary weak-link junct ions.