Time-domain terahertz spectroscopy of Bi2Sr2CaCu2O8+δ thin film

Time-domain terahertz (THz) spectroscopy was carried out on a c-axis oriented Bi2Sr2CaCu2O8+delta (BSCCO) thin film. We extracted various optical parameters at frequencies from 0.3 to 1.0 THz and temperatures from 5 to room temperature by numerically solving the observed complex transmittance without Kramers-Kronig analysis. As a result, the frequency dependence of surface resistance R-S showed different power laws of R-S alpha f (f < 0.5 THz) and R-S alpha f(1/2) (0.5 THz < f) in the superconducting state. Below the characteristic frequency, fc similar or equal to 0.5 THz, rapid increase in the density of supercarrier, Ns, was obtained. These obtained results well explained the electromagnetic-wave radiation property which had been observed on the same BSCCO thin film. (C) 2002 Elsevier Science B.V. All rights reserved.