Merging plasmonics and metamaterials by two-dimensional subwavelength structures

As one of the major fields of photonics in the last few decades, plasmonics takes advantage of the coupling of light and free electrons in noble metals, and allows the localization of light beyond the diffraction limit. Recently, plasmonics has been introduced into the newly emerging metamaterials, which are artificially structured effective materials with unique physical properties that do not exist in natural materials. Based on the strong light-matter interaction below the diffraction limit, the plasmonic metamaterials have found important applications in various photonic devices, such as color filters, flat lenses and perfect absorbers. In this review article, we focus on the planar plasmonic metamaterials that rely on the patterned arrangement of metallic and dielectric inclusions in the two-dimensional (2D) space. The interesting optical effects, underlying physical principles and the practical applications in functional devices are outlined, with a brief discussion of their future development trends.