Unexpected behaviour of IR reflectivity of a YBa2Cu3O7−δ oriented film

a−b plant oriented YBa2Cu3O7−δ films have been obtained by laser ablation. Electrical and structural characterization is presented as well as temperature dependent (4 K up to room temperature) optical reflectance spectra recorded between 50 cm−1 and 22 000 cm−1 Extra absorptions at low frequencies and low temperatures are analysed and their connection with a possible superconducting gap is discussed. It is emphasized that the overall conducting behaviour in the normal state is well described by a single Drude-like modified term.