One- and two-dimensional photonic crystals are obtained by electron beam lithography and reactive ion etching on silicon-on-insulator waveguides. Variable-angle reflectance is measured and calculated in the 0.2-2-eV energy range, giving evidence of the quasi-guided modes of the photonic structure. Photonic bands in the one-dimensional case are determined and compare very well to those calculated with an expansion on the basis of the waveguide modes.