Normal-state radiative properties of thin-film high-temperature superconductors

One of the first applications of thin-film high-temperature superconductors will be in the construction of liquid-nitrogen-temperature superconducting bolometers. Successful design of a bolometer requires sufficient knowledge of the radiative properties, and especially the absorptance, of the superconductor, if the superconductor is to interact directly with the incident radiation. At present, little quantitative information concerning the radiative properties of thin-film high-temperature superconductors is available to the designer. Here, a predictive model employing the Drude free-electron theory is applied to films of the order of 1 μm thick. The only measured parameter required by the model is the direct current electrical resistivity. Experimental data show good agreement with the model's results for far-infrared normal-state properties for the temperature range 100 K - 300 K.