Wednesday 13 April; Delft, Han Woerdman "Beam shifts for pedestrians"



Location: Room E, TNW
Time: 16:00 hrs


A light ray hitting a planar interface is reflected according to the specular reflection law of geometrical optics. In wave optics a light ray does not exist; however it can be approximated by a collimated light beam, such as a laser beam. Interestingly, when one tries to apply the laws of geometrical optics to such a “physical” ray one finds that these laws are slightly modified by diffractive corrections. For instance, a reflected physical ray may suffer a shift in the longitudinal or in the transverse direction, relative to the geometrical-optics prediction. These shifts can vary from much smaller to much larger than a wavelength. Moreover, there are not only positional but also angular shifts. The study of all these shifts has been reported in many hundreds of papers; key words are Goos-Hänchen shifts, evanescent fields, Imbert-Fedorov shifts and Spin Hall Effect of Light. Experimentally, this field has become accessible (and relevant) due to the progress in optical technology. There is also an appreciable activity to extend these notions to the case of quantum waves, e.g. matter waves. In the first part of the talk I will introduce the theoretical concepts and try to bring some order in this zoo of beam shifts; in the second part I will discuss some of our recent experimental work in this area.