Polariton Spectrum and Optical Features of Porous All-Metal One-Dimensional Plasmonic Photonic Crystal

Photonic crystal is an artificial metamaterial with a periodic superlattice resulting in photonic bandgaps in the visible spectrum. This allows the photonic crystal to act as an optical semiconductor and to create optical chips based on a photonic crystal technology. When a photonic crystal contains metallic inclusions, it becomes not only photonic, but also plasmonic and “works” both in optics and in electronics. This paper analyzes optical features of such a crystal made from a single metal, whose superlattice is formed during anodization under controllable etching (this leads to regularly alternating layers of different porosity in the same material). The analyses reveal the presence of a (very narrow) photonic bandgap and a (rather wide) plasmonic one in the polariton spectrum of the porously-structured metal. In the allowed spectral ranges, both quasi-linear normal and anomalous dispersion are observed, and in the anomalous region, the refraction of light is negative.