Controlling light through double-ring arrays

Coaxial structures are extremely crucial for investigations on surface plasmons since they exhibit special optical properties compared with apertures with other shapes. Different from the traditional extraordinary optical transmission (EOT) observed from nanohole arrays, these ring-like structures can excite cylindrical surface plasmon and planar surface plasmon simultaneously. The nanoring cavities can act as Fabry-Pérot resonators, giving rise to coupling between different modes. Importantly, these nanorings have found promising applications in fabricating color filters. Moreover, these coaxial structures are compatible with liquid crystal display techniques, leading to actively tunable optical devices which may be broadly applied in nanophotonics and integrated optics.