Robust edge states of subwavelength chiral phononic plates

Achieving strong robustness in elastic wave routing at subwavelength scale has always been a constant goal in practical applications such as energy harvesting, signal processing and sensor. Recently, topological phases have been widely extended from condensed matter physics to acoustics and mechanics to achieve robust control on the manipulation of acoustic and elastic waves. In this paper, we propose a chiral edge state at the interface between two subwavelength opposite chiral phononic crystals achieving edge state's robustness higher than the design with the topological C_6v design. The unit cell consists of an array of pillars resonators on a plate arranged in a honeycomb configuration with a chiral variation of their resonant frequencies. It is shown that the robustness of the chiral edge states to defects and perturbations is stronger than that of the topological C_6v-symmetry waveguide systems. Furthermore, the harvesting powers of the chiral mechanical systems also show stronger robustness against the frequency disorder and the position disorder and are at least an order of magnitude higher than that of the C_6v designs. Our proposed chiral mechanical systems are foreseen to provide support for the design and manufacturing of miniaturized solid devices for vibration control and sensing.