Study on he multimode and single-mode propagation characteristics of variable size chain structures

In this paper, a periodic chain composed of a two-dimensional single-layer dielectric cylinder is studied by the Fourier series expansion method combined with the perfectly matched layer approach. The phase constant and attenuation constant of the conduction mode, the forward propagation leakage mode, and the backward propagation leakage mode are analyzed conceptually under different radii. Then, the numerical properties and field pattern distribution characteristics of single-layer cylindrical periodic structures of different radii are discussed. The odd and even modes are found to coexist in structures with a larger radius, which can be applied to transmission devices such as multimode communication. However, there is only a single mode in structures with a smaller radius, which can reduce cross talk and is applicable to single-mode communication. In addition, the mode-guiding capability of a finite array with only 20 medium rods under plane mode excitation of a specific mode length is discussed. The finite array with different conducting capabilities (propagation, attenuation, cutoff) can be used in mode guiding, sensors, filters, etc. (C) 2020 Optical Society of America