Optical Properties of Bi-Sr-Ca-Cu-O Thin Films

The optical reflectivity and absorption spectra for the Bi 2 Sr 2 Ca n -1 Cu n O x systems ( n =1, 2 and 3) were measured at room temperature using c -axis-orientated films. In the reflectivity spectra, the increase of n enhanced a Drude-like reflection and shifted its plasma edge to the shorter-wavelength region. In the absorption spectra, a near-infrared absorption was enhanced with increasing n , contrasting with an insulating Bi 2 Sr 2 NdCu 2 O x film where an interband absorption in the visible region was dominant. These features should reflect the electronic structure which gives rise to the superconductivity.