A comparison of the nonbolometric microwave response with the bolometric optical response of Tl- and Bi-oxide superconductors

The distinction between the bolometric and nonbolometric responses of high-T/sub c/ Tl- and Bi-oxide superconducting thin films is presented by comparison of the characteristics of the responses at different temperatures and chopping frequencies. The bolometric optical response of the films is proportional to the dR/dT of the films; experimentally, the peak optical response decreases as the chopping frequency of the radiation is increased. The nonbolometric response is not proportional to the dR/dT of the films, and the peak microwave response was found to be almost independent of the chopping frequency. It is found that both components can be observed in the microwave response of a superconducting epitaxial film. The optical response of a continuous-wave (CW) He-Ne laser is mainly due to the bolometric effect, whereas the microwave response using a 34.5-GHz Gunn diode microwave generator is predominantly nonbolometric.<
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