FLUCTUATION-INDUCED PSEUDOGAP IN THE INFRARED OPTICAL CONDUCTIVITY OFHIGH-TEMPERATURE SUPERCONDUCTORS

We study the effect of fluctuations on the ac conductivity of a layere d superconductor both for c-axis and ab-plane electromagnetic wave pol arizations. The fluctuation contributions of different physical nature and signs (paraconductivity, Maki-Thompson anomalous contribution, on e-electron density of states renormalization) are found to be suppress ed by the external field at different characteristic frequencies (omeg a(AL)similar to T-T-c, omega(MT)similar to max{T-T-c,tau(phi)(-1)}, om ega(DOS)similar to min{T,tau(-1)} for the two-dimensional case). As a result the appearance of the nonmonotonic frequency dependence (pseudo gap) in the infrared optical conductivity of high-temperature supercon ductor film is predicted. The effect has to be especially pronounced i n the case of the electromagnetic field polarization along the c axis.