Nonspecular first-order effects in Kretschmann's configuration

First-order nonspecular effects for Gaussian beams reflected on the first interface of a system formed by two interfaces of isotropic materials are studied. The complex lateral displacement is analytically determined and the validity of the approximations made is analysed. It is shown that the lateral displacement is independent of the beam waist and the approximation results suitable even for very narrow beams near Brewster's condition. With a dielectric-metal-dielectric configuration (Kretschmann's) and under resonance conditions, lateral displacements of up to 25% of the beam width can be obtained.