Microwave detection using granular Bi-Sr-Ca-Cu-O thin films

We report here results of our investigations of the nonbolometric mode of detection in granular Bi-Sr-Ca-Cu-O thin films. We find that both bolometric and nonbolometric modes appear in the same sample under mutually exclusive conditions: bolometric with light (633 nm) and nonbolometric with microwaves (9 GHz). Our measurements indicate that the nonbolometric mode of detection is more sensitive than the bolometric mode in our samples, a result which offers promise for application to microwave power measurement. Possible mechanisms for the nonbolometric mode are reviewed, and the concept of using a broadband spiral antenna directly coupled to the superconducting detector for microwave power sensing is briefly described.