Broadband surface wave attenuation in periodic trench barriers

Abstract

Surface wave manipulation in periodic trench barriers based on real band structures has its inherent limitations. This work revisits this problem from the perspective of complex band structures. To this end, a numerical model using the finite element method is first derived based on a physical model and formulations, which is validated through good correlations between its results and those from existing studies. Next, the model is used to conduct a parametric study to evaluate the effect of different geometrical parameters and material damping. Results indicate that the complex band structure can accurately capture the decay of surface waves and characterize periodic systems with damping. Wide evanescent surface-wave regions, including the band gap and leaky surface modes, exist in periodic trench barriers. These regions are more robust when proper geometrical and material parameters are selected, thus more effectively enabling the realization of broadband surface wave attenuation using periodic trench barriers, which is confirmed in both frequency and time domains.