Disorder‐Assisted Topological States and Critical Couplings in Continuous Elastic Metaplates

ABSTRACT Precise manipulation of elastic waves in continuous solid‐state media is important for enhancing wave‐matter interactions and enabling applications such as energy harvesting, nondestructive testing, sensing, and on‐chip signal processing. Disorder is typically regarded as detrimental to wave propagation. However, disorder can drive a trivial phase into a nontrivial one, leading to the emergence of a topological Anderson insulator (TAI). While existing TAI studies mainly focus on idealized systems such as discrete lattice models or resonator arrays, here we realize the disorder‐engineering principle in a scalable continuous elastic plate for topological states and waveguide‐cavity critical couplings. Disorder is introduced by randomly rotating perforated elliptical holes in a continuous plate. The disorder‐assisted bandgap closing and reopening, and interface states with suppressed backscattering, are verified experimentally. We also develop a super‐periodic equivalent model that quantitatively predicts the disorder‐driven bandgap evolutions and topological transitions. Beyond robust transport, we realize disorder‐assisted critical couplings in a TAI waveguide‐cavity system, whereby most waveguide energy is coupled into the resonator, with possible applications in signal filtering and multiplexing. Our work introduces a disorder‐engineering strategy for manipulating wave phenomena in continuous solid‐state media. We expect these results to inspire further advances in integrated phononic circuits and on‐chip technologies.