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In this talk, we discuss realistic metamaterial structures to realize the concept of real-space gauge field. Light propagation can be modified in conventional optical media by changing the sizes and the shapes of their dispersion surfaces. Alternatively, a real space gauge field approach can also manipulate light propagation by shifting the centers of the dispersion surfaces [1–4]. Such a real space gauge field, together with the associated pseudo magnetic field in real space, has been applied to achieve novel wave phenomena such as negative refraction, one-way waveguide, spin-Hall effect, and one-way topological edge states. Recently, we have also proposed that such a gauge field in real space can be synthesized by a tilted anisotropic metamaterials [5, 6]. With such gauge field metamaterials, spin-dependent optical components such as beam splitter and all-angle wave plate can be designed. We will discuss the underlying metamaterial structures in achieving such a real space gauge field, by realizing the two shifted dispersion surfaces. On one hand, in the ideal case we generally require a 45 degree tilted anisotropic metamaterial with dedicated balance of electric and magnetic responses. This can be realized by a metamaterial unit cell composed of a split-ring resonator and a metal bar which both have 45 degrees rotation from one of the principal axis. The split-ring resonator provides the magnetic response while the metal bar works as a tuning for the detailed balance. On the other hand, we further establish a reduced parameter approximation to simplify experiments. In this case, the metamaterial is still 45 degree tilted anisotropic medium, but the magnetic response is dropped. Only the electric responses in different directions are needed to realize the real space gauge field in a reduced parameter approximation.

Photonic graphene, photonic crystal with honeycomb lattice is studied in the work. Using both finite element simulations and microwave experiments, we studied the existence of the edge modes at different edges of this “photonic graphene”. The edge states are observed experimentally on the bearded interfaces of photonic crystals. The physics of the occurrence of these edge modes are discussed and we hope that the fabrication easiness of photonic crystal makes it a perfect platform for classical simulations of electronic transport properties in graphene.

Ever since the introduction of metamaterials, intriguing applications have been proposed by metamaterial designs. An e = μ = −1 slab will serve as a super lens to break diffraction limit. This slab, whose permittivity and permeability is with the same magnitude but of different sign to air, is the complementary medium to air. Lai et al. proposed the possibility to remote cloaking using complementary medium. However, the metamaterial design to have complementary medium realized is complicated and there are experimental demonstrations are limited. Conical dispersion can exist at the Brillouin zone center of two-dimensional photonic crystals and this dielectric photonic crystal can be regarded has an effective zero permittivity and permeability at the Dirac frequency. Close to the Dirac frequency, effective permittivity and permeability are linear to frequencies. Moreover, because of the scaling property of Maxwell's Equation, if the linear dimensions of the structures in a given dielectric PC are scaled uniformly by a factor of α, the frequency ω and wave vector k should also be scaled according to the relations ω = ω/α and k = k/α [1]. Thus a complementary medium can be realized by stacking two photonic crystal slabs scaled uniformly. Our simulations and microwave experiments give a direct demonstration of the phase compensation effect of the complementary medium. Vortex interface states in complementary medium are experimentally observed and one dimensional remote cloaking is proposed.

We theoretically and experimentally demonstrate that by utilizing a new freedom introduced by spatial dispersions in the effective parameters, Brewster effect can be extended from a single angle to a range of angles, enabling wide-angle impedance matching and total transmission of light through the surface. By designing pure dielectric photonic crystals with spatial dispersions, we demonstrate an approach to achieve the omnidirectional total transparency and aberration-less virtual image. Our work reveals rich possibilities like wide-angle loss-less super-polarizer and transformation optics devices with additional phases beyond the local medium description.

In this paper, we reviewed some recent studies on planar metamaterials and demonstrated two new way to realize high directive antenna for the first time: 1) Quasi-periodic metamaterial surface can suppress transverse-electric (TE) surface waves and support directive emissions. 2) Periodic metamaterial surface can be applied in realizing one-dimensional subwavelength Fabry-Perrot (FP) metamaterial cavity which support directive emissions. We show both experimentally and theoretically that these phenomena mainly originate from the dispersive reflection phase and surface wave dispersions.

We report our experimental and theoretical studies on a metamaterial substrate consisting of a quasi-periodic metallic planar pattern and a flat metal sheet, interconnected through metallic vias. We show that this structure possesses multiple in-phase reflection frequency regimes and spectral gaps for transverse-magnetic surface waves, whereas the transverse-electric surface waves are suppressed in all frequencies. In particular, an antenna put on top of this planar structure radiates with very high directivity (D=240) at some frequencies. This phenomenon is mainly governed by the inhomogeneity of the structure, which is a collective effect of perfect magnetic and electric conductors operating simultaneously at the frequency.