Detection of interface states in an elastic plate using laser ultrasonic technology

An interface state of elastic waves in mirror-symmetric structured waveguides has been detected using laser ultrasonic technology. In antisymmetric periodic waveguides, the resonance coupling of different transverse guided modes can lead to a non-Bragg gap in the frequency domain. When two antisymmetric periodic waveguide structures with mirror-symmetry properties are combined, the elastic waves resonate locally at the connection, resulting in an observable elastic wave interface state. Simulations and experimental measurements confirm the generation of additional modes in the non-Bragg gap, giving rise to the interface states of the elastic waves. In addition, we examine the frequency shift mechanism of the interface states and find that the frequency of the interface state linearly depends on the connection length at the center of the waveguide. The discovery of interface states in mirror-symmetric elastic waveguides and their regulation provides important theoretical guidance for designing and preparing elastic waveguide structures. These have broad application prospects in elastic wave signal detection, modulation, and filtering.