Optical Hall effect

Physicists in Japan have shown theoretically that an optical equivalent of the Hall effect exists and that it should be seen in experiments with polarized light. In the classic Hall effect, an electric current pulled along a conductor by an electric field will be deflected sideways if a magnetic field is applied perpendicular to the electric field. The physicists say that, due to the topological aspects of light, something similar should happen when a polarized light ray moves from one medium into another. The angles of the reflected and refracted rays with respect to the incident ray still obey Snell’s law, but the rays no longer all lie exactly in the same plane. The amount of the sideways shift at the deflection will depend on the change in the index of refraction between the two media. Masaru Onoda at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, and his colleagues at the University of Tokyo believe that the effect can be explored in upcoming experiments using photonic crystals. (M. Onoda et al. , Phys. Rev. Lett. 93 , in press.)