OPTICAL-RESPONSE OF SINGLE-CRYSTAL AND BICRYSTAL YBA2CU3O7-DELTA THIN-FILMS

We have investigated the optical response of YBa2Cu3O7-delta grain bou ndary junctions as well as single crystal strip lines. For both device s, bolometric signal was detected between T(c)(zero) and T(c)(onset), whereas nonbolometric signal was observed only in a temperature range just above T(c)(zero) where the current-voltage characteristic showed nonlinear behavior. The content of nonbolometric signal in the total r esponse signal was remarkably increased with decreasing the film thick ness. The effect of a single grain boundary on the nonbolometric respo nse was described.