Institute of Fundamental Technological Research

The net displacement of the intensity peak in relatively narrow Gaussian beams reflected at a dielectric interface is shown to be produced by a combination of four distinct nonspecular effects, namely, lateral, focal, and angular shifts and a modification of the beam-waist magnitude. We also find that these effects cause the axis of the reflected beam to follow a trajectory that depends on the beam width and on the distance from the waist of the geometric-optical reflected beams. To determine all the details of this nonspecular behavior, we derive a new expression for the reflected field; in contrast to previously reported results, this expression also holds for small beam widths and for incidence angles equal or close to the critical angle of total reflection. Our derivation yields accurate results for the four distinct nonspecular effects and provides a consistent explanation of the available experimental data on the net displacement of the beam peak.