Measuring the Magnetism of Light

When light interacts with matter, the dominant action is often a “shaking” up and down of electrons in response to the electric field. This interaction is typically 10,000 times larger than the “swirling” action from a light wave’s magnetic field. The case is different in metamaterials, which contain small components like metal rings that are often tailored to have an enhanced response to magnetic fields. Thanks to this sensitivity, light traveling through a metamaterial can bend in unusual ways, making feasible such devices as super-lenses and invisibility cloaks.