Nonspecular phenomena in beam fields reflected by multilayered media

Past studies have shown that beams reflected by a single dielectric interface exhibit lateral and focal shifts under total-reflection conditions or angular shifts if a partial reflection regime is maintained. We investigate these effects for Gaussian beams incident upon multilayered media by using an analysis that treats the three beam-shifting phenomena in a unified manner. This approach reveals a novel fourth effect that manifests itself as an expansion or a reduction of the beam waist. All the four nonspecular phenomena are evaluated for typical layered configurations, and simple approximate relations are derived. The results show that the reflected beam fields may be considerably different from those predicted by geometrical optics if incidence occurs at an angle around which the reflectance function varies rapidly.