Unidirectional Excitation of Radiative-Loss-Free Surface Plasmon Polaritons in PT-Symmetric Systems.

We investigate the excitation and propagation of surface plasmon polaritons (SPPs) at a geometrically flat metal-dielectric interface with a parity-time (PT) symmetric modulation on the permittivity ϵ(x) of the dielectric medium. We show that two striking effects can be simultaneously achieved thanks to the nonreciprocal nature of the Bloch modes in the system. First, SPPs can be unidirectionally excited when light is normally incident on the interface.

Coherent-trapped helical mode in parity-time symmetric metamaterials.

Coaxial optical subwavelength elements support helical modes Lm with different topological indexes m. Here we propose to couple the two bright L modes with the dark one L via a parity-time (PT) symmetric perturbation. We show that the cascading coupled configuration is similar to a three-level atomic system, and supports a special hybridized mode Lc via a classic analog of coherent-population-trapping effect.

Localization and oscillation of optical beams in Moiré lattices.

We study the propagation of optical beams in two-dimensional Moiré lattices, and demonstrate position-dependent beam dynamics when a quasi-Bragg condition is satisfied. We show that when the optical beam is incident to a peak of the lattice envelop, an optical Zitterbewegung is obtained. If the optical beam is incident to a node of the envelop, a field localization effect takes place.

Optical spin-sensitive Zitterbewegung in bianisotropic metamaterials.

We present a theoretical analysis on optical spin-sensitive Zitterbewegung (ZB) in metamaterials. By developing some formulas about the dispersions and eigenstates of optical modes we show that spin-sensitive ZB can be obtained in a bianisotropic metamaterial with a proper coupling between the electric and magnetic responses. A close analogue of the developed analytical results with these of Dirac equation is proposed.