Tunable metallic photonic crystals with an effective negative index of refraction

This paper presents a study of metallic photonic crystals with a 2D square lattice of cross shaped scatterers. It is found that even a small volume fraction of metal (when compared to rod shaped scatterers) creates more and wider bands with the required curvature for backward wave behaviour. Furthermore, these bands can easily be tuned and isolated (in the spectrum) by changing the dimensional characteristics of the crosses. Our design process was simplified by first tuning the shapes of the bands with the metallic crosses, and then scaling the bands to the desired frequency by immersing the crosses in a dielectric background.