Broadband valley-locked waveguide states of elastic wave in topological phononic crystal plates with asymmetric double-sided pillars

Abstract

Here, a broadband topological valley-locked waveguide state (TVWS) of elastic wave with adjustable mode width is reported in the phononic crystal plate with asymmetric double-sided pillars. The broadband topological bandgap is achieved by adjusting the height of triangular pillars. The TVWS with adjustable mode width is realized by adding a pillared phononic crystal (PPnC) with Dirac points between two valley PPnCs with distinct topological phase. The TVWS of elastic wave exhibits the properties of gapless dispersion and robustness against bends and disorders. Based on the TVWS, an elastic valley-locked waveguide splitter with variable mode width is further demonstrated.