Non-reciprocal Rayleigh wave propagation in space-time modulated surface

Research on non-reciprocal propagation of waves is of great significance in the field of photonic and phononic crystals for realizing flexible one-way propagation devices with potential engineering applications. Here, non-reciprocal Rayleigh waves are investigated in a continuous two-dimensional (2D) semi-infinite medium bound with an array of space-time modulated spring-mass oscillators. The involved modulation is a wave-like perturbation of the surface of the continuous medium that breaks time-reversal symmetry and reciprocity. To characterize the propagation of Rayleigh waves in such a complex 2D medium with continuous and discrete interface, an analytical study is performed to obtain dispersion-engineered bandgaps by adopting the asymptotic method and coupled mode theory, which is also validated by numerical simulation. Specifically, the non-reciprocal transmission of Rayleigh waves with one-way mode conversion is illustrated, and various relevant physical quantities, including conversion length and band gap size, are quantitatively estimated. This work sheds light on versatile control of Rayleigh wave propagation ranging from sensing and evaluation of engineering structures to guided wave-based damage detection techniques.

Automated summary

The research investigates non-reciprocal Rayleigh wave propagation in a continuous two-dimensional medium, utilizing a modulated array of spring-mass oscillators to break time-reversal symmetry and reciprocity. Analytical study and numerical simulation are conducted to characterize the propagation and validate dispersion-engineered bandgaps, providing insights for versatile control of Rayleigh wave propagation.