Absorption and lateral shift of beams incident upon lossy multilayered media

The reflected field produced by a beam incident upon planar multilayered structures having small losses is examined by using both an approximate approach and a highly accurate Gaussian-beam analysis. In particular, situations are considered wherein high absorption of the incident energy flux occurs when a generalized Brewster-type regime prevails. We find that the high-absorption phenomenon is due to the large lateral displacement of the beam on its reflection under certain critical conditions. For small losses, this beam shift occurs in a forward direction, similar to that in ideally lossless media; however, for losses that are above a certain critical value, the beam shift appears in an unexpected backward direction. Our results show that all these effects are accounted for by the interaction between the incident energy and a leaky wave that can be supported by the multilayered structure.