Tunable unidirectional large-area surface magnetoplasmons in a stratified waveguide

Large-area unidirectional modes have attracted increasing attention due to their potential applications in wave manipulation; however, most implementations are constrained by poor adjustment capability or narrow operating bandwidth, since minor structural parameter changes may significantly affect the one-way propagation range. In this work, we propose and investigate a robust and broadband unidirectional large-area surface magnetoplasmon (LSMP) mode in a stratified waveguide consisting of magnetized yttrium iron-garnet, air, and μ-negative materials. Through theoretical analysis and numerical simulations, we demonstrate that the electric field with uniform amplitude and a nearly flat phase profile can be achieved in the tunable one-way range by adjusting the filling ratio of μ-negative materials. Relying on this unique electric field distribution, we demonstrate beam focusing, Bessel beam generation, and an adjustable beam splitter using LSMP modes. These results are expected to be applied in the field of all-optical communication and imaging, such as efficient holographic imaging.