La1−xSrxMnO3 manganite films with x=0.15, 0.33 and 0.4 were deposited onto silicon substrates by pulsed laser deposition in an 80/20 Ar/O2 atmosphere at room temperature. After being deposited, the films were annealed at 900 °C in air in order to obtain the desired crystalline phase. Structural characterizations using X-Ray diffraction showed polycrystalline compounds having the predominant peaks corresponding to the perovskite structure. Morphological studies carried out by scanning electron microscopy revealed a very rough surface and led to deducing the nature of the growth process. Spectral ellipsometry was performed between 1.5 and 5 eV range at room temperature, showing electronic transitions near to 2.2 and 4.7 eV in a range of thicknesses between 94 and 107 nm.