In this paper, we numerically and experimentally demonstrate the existence of complete band gaps and resonances in a plate with a periodic stubbed surface. Numerical results show that a complete band gap forms as the stub height reaches about three times the plate thickness. In the experiment, we used a pulsed laser to generate broadband elastic waves and used optical devices as well as point piezoelectric transducers to detect wave signals. The results show that the numerical predictions are in very good agreement with those measured experimentally. Remarkable resonances on the top surface of the stubs are found and discussed.

Successful application of photonic crystals has led recently to a rapidly growing interest in the analogous acoustic effects in periodic elastic structures called phononic crystals. This study is aimed at developing a theory for two-dimensional phononic crystal consisting of materials with general anisotropy. Explicit formulations of the plane harmonic bulk wave and the surface wave dispersion relations in such a general phononic structure are derived based on the plane wave expansion method. Two-dimensional phononic structures with either the square or the hexagonal lattice are considered in the numerical examples. Band gap characteristics of the phononic structures with different anisotropic background materials ͑isotropic, cubic, hexagonal, and ortho-rhombic͒ are calculated and discussed.

In this paper, we investigate the frequency band-gap features of micromachined air/silicon phononic band structures using layered slanted finger interdigital transducers (SFIT). In order to achieve the applications of phononic crystals on the microelectromechanical system related components, the frequency band-gap widths of surface waves are studied both theoretically and experimentally in micrometer scale phononic crystals. For further integration with the complementary metal-oxide semiconductor processing techniques, silicon is chosen as the base material of the two-dimensional phononic crystals in this study. To cover the frequency band-gap width of the phononic crystal, the wideband SFIT- and the SFIT∕ZnO∕Si-layered structures in the measurement are analyzed and discussed. For layered structures, the dispersive relation is calculated by the effective permittivity approach, and the frequency response of the layered SFIT is then simulated by the coupling-of-modes model. The frequency band-gap width and the frequency range of two-dimensional air/silicon phononic crystals in micrometer scale are measured, and the result agrees well with the theoretical evaluation.

In this paper we analyze the phononic band structure of bulk and surface waves in a two-dimensional periodic structure consisting of an array of piezoelectric cylinders in an isotropic background material. The explicit formulations of the bulk wave and the surface wave dispersion relations in such a structure are derived based on the plane wave expansion method. The band gaps and the electromechanical coupling coefficients for surface acoustic waves propagating in such a structure are calculated. The influences of material and geometrical anisotropy as well as the filling fraction on the electromechanical coupling coefficients are discussed, and some silent features are drawn. The results of this research may serve as an important reference for studying surface acoustic wave devices consisting of phononic structures.

This paper discusses the phenomenon of phononic crystal silicon-based filters, resonators and acoustic channels structured in geometrical periodic arrays created by a single silicon material. Component structured geometrical periodic array refers to a structure of square stubbed rods arranged in repeated arrays on a silicon plate. The study discovered that the band gap of the phononic crystal structure can be modulated under different heights and rotational angles of periodically arrayed square stubbed rods. In addition to band gap modulation, we used the finite element method (FEM) and supercell techniques to analyse the resonance characteristics of defect-containing phononic crystal structures with a larger band gap size design. In addition, the paper also investigated the effects on acoustic channels. Previous studies have already analysed defect-containing resonator and channel phenomenon by the plane-wave expansion method with supercell techniques. However, the FEM can solve numerical issues of extreme difficulty to reach convergence. The results of this study elaborated on the manufacturing feasibility of silicon-based acoustic resonance and filter devices under a complementary metal–oxide–semiconductor synchronization process.