This substrate is coated with a composite film based on a mesoporous mineral layer containing nanoparticles formed in situ inside the layer. The composite film has a periodic lattice structure over a major portion of the thickness in which the nanoparticles are present, in which structure the nanoparticles are arranged in a periodic manner on the scale of domains of at least 4 periods in the thickness of the film.This structure can be obtained from a mesoporous mineral layer of periodic structure on the scale of domains of at least 4 periods of pores, forming a matrix on the substrate, by: depositing at least one precursor in the pores of the matrix layer; and growing particles derived from the precursor with the spatial distribution and the dimensions being controlled by the structure of the pores of the matrix. Applications to materials for electronics, nonlinear optics and magnetism.