Hyperbolic Dispersion via Symmetric and Antisymmetric Orderings of Artificial Magnetic Dipole Array

We report a theoretical and experimental study in achieving the hyperbolic dispersion via the symmetric and antisymmetric hybridization of two-dimensional (2D) artificial magnetic dipoles using metasurfaces possessing artificial magnetic resonance at optical frequencies. Due to the mutual competition among the longitudinal and transverse coupling of the artificial magnetic dipoles, the metasurfaces exhibit distinct red/blue shifts for the incident wavevectors along the orthogonal directions. The resulting saddle-shape isofrequency surfaces possess the hyperbolic dispersion at the frequencies above and below the saddle-point. Our findings not only provide distinct k-space topology beyond the hyperboloid isofrequency surfaces being reported in the literature, but can also inspire new approaches for the design of hyperbolic materials.