Author(s): Gao Penglin, Sánchez-Dehesa José, Wu Linzhi
An incoming wave can be redirected into the perpendicular directions in periodic systems when its wavelength is similar to the lattice period. This wave motion property was termed as the Poisson-like effect in analogy to the phenomenon in which the deformation of solid materials couples in two perpendicular directions. For flexural waves propagating in a thin plate, the effect of 90^o redirection of elastic energy is observed in platonic crystal slabs consisting of periodically perforated free holes. It is demonstrated that the coupling of leaky guided modes with the propagating waves contributes to the anomalous wave motion. For smaller holes, Poisson-like wave motion occurs in company with the Wood anomaly, featured as total reflection due to the excitation of stationary waves propagating along the slab. With the increasing of the size of the holes, the eigenmode gradually evolves to a mixed guided mode featured as waves propagating in two orthogonal directions. In this case, however, the Poisson-like effect is excited when the incoming wave is totally transmitted. This work investigates the evolutionary process of the leaky guided modes and may find an application in energy redirection and waveguiding of flexural waves in platonic crystals.
Name: Prof jose sanchez-dehesa