Spectral dependence of nonbolometric far‐infrared detection with thin‐film Bi2Sr2CaCu2O8

Abstract

The photoresponse of granular current biased thin‐film Bi2Sr2CaCu2O8 superconductor to short pulse far infrared radiation has been measured for 16 laser lines, with frequencies between 10 and 1000 cm−1. A strong dependence of the signal on the frequency ω, approximately proportional to ω−2.3, is observed. It is shown, by calculations based on the resistively shunted junction model, that this photosignal can be understood to arise from the ac Josephson effect at grain boundary weak links.