On the basis of the linear response theory, we consider the collective electromagnetic properties of a semi-infinite photonic crystal which is contacting with vacuum. The photonic crystal system consists of alter-nating superconductor-dielectric slabs of different thicknesses. The bulk photonic band structure and the corresponding localized modes, arizing due to the broken translational symmery, are considered. It is shown that, as well as the magnitude of the in-plane wave vector rises, the frequency of the lowest local-ized mode increases, as well as the highest-frequency localized mode decreases. On the other hand, for a fixed in plane wave vector there appear additional modes in the band gap, in such a way that if the superconductor layer contacts with vacuum, there is a mode in the superconductor gap which exists for in-plane wave vectors above a critical non zero value. The results are illustrated with dispersion curves of the bulk and localized modes.