<title>Residual absorption of high-temperature superconductors at THz frequencies</title>

Abstract

We report on a study of the residual absorption of high temperature superconductors (ff15) at THz frequencies. Using transmission Fabry-Perot interferometry, we determined both, real and imaginary part ofthe conductivity. We especially studied YBCO thin films. We found, that the dynamical conductivity varied strongly from sample to sample. As a main result we find, that the absorptivity increases at frequencies above 1 THz much weaker than quadratically, ie. the o2 behaviour of the absorptivity at microwave frequencies is not continued in the THz frequency range.