Tailor-made surface swaps light polarization

Manipulating the properties of light—amplitude, phase, and polarization, for instance—typically involves using an array of lenses, polarizers, and other elements on an optical table. Two-dimensional metamaterials called metasurfaces offer a compact alternative based on the engineering of subwavelength structural features to achieve specific electromagnetic properties. For example, Anthony Grbic and his colleagues at the University of Michigan have designed and fabricated a new type of asymmetric circular polarizer. As illustrated here, their 400-nm-thick device consists of three patterned gold surfaces separated by dielectric substrates. When right-handed circularly polarized (RHCP) light is incident on one side of the metasurface, it emerges from the other side as left-handed circularly polarized (LHCP) light. At the operating wavelength of 1.5 μm, the transmittance for RHCP to LHCP is 50% whereas for other combinations — LHCP to RHCP, LHCP to LHCP, and RHCP to RHCP — the transmittances are below 2.5%. What’s more, the device...