Independent design method of multiple surface modes using a domino-ring structure​

Abstract

This paper proposes a method for generating and independently controlling multiple modes of surface modes using a domino-ring structure. The domino structure, which forms a waveguide, gives a reference potential to the ring structure to realize a waveguide in which multiple surface modes are formed. The two-dimensional periodic structure of the ring mimics the helical edge state, one of the characteristic properties of topological materials, and the number of modes is independent of the shape. The quasi-two-dimensional periodic structure obtained by stacking the ring structure and combining it with the domino structure multiplexes the surface modes and produces coupling modes as the complimentary modes. Eigenvalue analyses are performed to calculate the dispersion relations for the domino, ring, and domino-ring structures, and the results were compared with the theoretical curve for the domino structure and the fitting curve for the ring structure, and the mode controllability and skin depth of the modes are discussed. The results show good agreement between the theoretical and fitting curves and the analytical results and also confirmed that the modes are generated according to the number of rings in the unit cell. And it confirmed that the skin depth of the multiple surface modes on the domino-ring structure varies with each coupling point and can be controlled by the exciting condition.