Fig. 1.

Schematic of a cavity-embedded honeycomb metasurface. The honeycomb array of meta-atoms is composed of two inequivalent (A and B) hexagonal sublattices—defined by lattice vectors ${\mathbf{a}}_1=a\left(-\frac{\sqrt{3}}{2},\frac{3}{2}\right)$ and ${\mathbf{a}}_2=a\left(\frac{\sqrt{3}}{2},\frac{3}{2}\right)$—which are connected by nearest-neighbor vectors e₁ = a(0, −1), ${\mathbf{e}}_2=a\left(\frac{\sqrt{3}}{2},\frac{1}{2}\right)$, and ${\mathbf{e}}_3=a\left(-\frac{\sqrt{3}}{2},\frac{1}{2}\right)$, where a is the subwavelength nearest-neighbor separation. Each subwavelength meta-atom is modeled as an electric dipole, oriented normal to the plane of the lattice. The honeycomb metasurface is then embedded inside a photonic cavity of height L, which is composed of two perfectly conducting metallic plates, enabling one to modify the photonic environment while preserving the lattice structure. This general model can be readily realized across the electromagnetic spectrum, from arrays of plasmonic nanorods to microwave helical resonators