Manipulation Of Photonic Angular Momentum States Based On Subwavelength Structure Of Coaxial Cavity

Investigating the optical properties of materials is the intersection of Optics and condensed matter physics which are two major branch disciplines of physics. The classical Maxwell equations can describe the propagation of light in the material precisely. The classical Maxwell equations contain two important parameters ε and μ in order to describe interaction between materials and light. Theoretically, we can control light propagation by changing ε and μ. In recent years, the microstructure materials composed by a special artificial metal nano-micro structure unit, achieves some very interesting phenomena. Under the action of magnetic field, the interaction of optical field and Magneto-Optical media shall generate Magneto-Optic effect, then the ε or μ of Magneto-Optical media will change, the most common situation is that the Magneto-Optical media emerges anisotropism, under this circumstance, we utilize second order tensor to express ε or μ. Metamaterial and Nano-Optics are two key research field of modern Optics, we combine Magneto-Optical media and subwavelength metal microstructure, which can constitute a special Metamaterial. Hence we can manipulate the resonance through the Magneto-Optic effect in subwavelength metal microstructure.Based on Finit Element Method simulations, we propose a novel scheme in realizing tunable slow-light performance by manipulating dark photonic angular momentum states (PAMSs) in metamaterials via the magneto-optical (MO) effect. We show that by applying a static magnetic field B, some pairs of sharp transmission dips can be observed in the background transparency window of a complex metamaterial design. Each pair of transmission dips are related to the excitation of dark PAMSs with opposite topological charges -m and +m, with a lifted degeneracy due to the classic analogue of Zeeman effect. Nonreciprocal characteristics can be observed in the distributions of field amplitude and transverse energy flux. The performance of slow light, including the group index ng, its abnormal feature, the associated strong absorption and the dependence with B are also discussed.To further understand the basic physical mechanism of PAMSs, by rigorously solving Maxwell’s equations, we develop a full-wave electromagnetic theory for the study of PAMSs in coaxial magneto-optical waveguides. Paying attention to a metal-MO-metal coaxial configuration, we show that the dispersion curves of the originally degenerated PAMSs experience a splitting, which are determined by the off-diagonal permittivity tensor element of the MO medium. We emphasize that this broken degeneracy in dispersion relation is accompanied by modified distributions of field component and transverse energy flux. A qualitative analysis about the connection between the split dispersion behavior and the field distribution is provided. Potential applications are discussed.