Unidirectional and robust propagating surface magnetoplasmon in magneto-optical coaxial waveguides

In this paper, a novel coaxial waveguide comprising a hollow cylinder made of a magneto-optical material and a metal wire at the axis is proposed. The surface magnetoplasmon and guided modes of the waveguide are studied. The results show that the dispersion relation and electromagnetic field distribution are highly sensitive to the operating frequency and physical dimensions of the structure. It is demonstrated that there exist three different types of modes, that is bulk mode, surface mode, and regular mode. By adjusting the operating frequency and reducing the inner diameter of the hollow cylinder, the regular mode is suppressed and only the surface mode remains, which shows one-way propagating property. Moreover, the one-way surface mode is robust against backscattering at defect and surface roughness, which has good potential in practice. The unique properties of this waveguide are demonstrated through mode analyzes as well as numerical simulations. (C) 2020 The Japan Society of Applied Physics