Rigorous analysis of the spatial dispersion effect in multilayer thin-film coatings

We demonstrate a wavelength-dependent spatial lateral beam shift of a reflective Gaussian beam on the surface of multilayer thin-film coatings. Numerical analysis of the behavior of a Gaussian-form light beam incident on the surface of the coatings is performed. The theoretical analysis is for a two-dimensional light sheet. The spatial lateral beam dispersion can be determined rigorously from the numerical wave field in the region of the incident medium. The coatings present a spatial dispersion effect much larger than in previous reports. The thin-film coatings can act not only as positive spatial dispersion devices but in a proper case, also as negative spatial dispersion devices. As such, the devices produce a wavelength-dependent negative lateral shift of the reflective beam.