Grating resonances on periodic arrays of sub-wavelength wires and strips: Historical narrative and possible applications

This paper reviews the history of discovery and the study of the nature of the high-quality natural modes existing on periodic arrays of sub-wavelength scatterers as specific periodically structured open resonators. Here, the arrays can be finite and infinite, and their elements can be dielectric and metallic. These grating modes (G-modes), like any other natural modes, are the “parents” of corresponding resonances in the electromagnetic-wave scattering and absorption. In the scattering cross-sections, they are usually observed as Fano-shape (double-extremum) resonances, while in the absorption they always display conventional Lorentz-shape peaks. Thanks to high tunability, the G-resonances can potentially supplement or even replace the better known surface-plasmon resonances in the design of nanosensors, nanoantennas, and nanosubstrates for surface-enhanced Raman scattering.