An approach to calculate reflectivity of the 2-D phononic crystals reflecting gratings in two directions

As a new structure, reflecting gratings based on two-dimensional (2-D) piezoelectric phononic crystals (PCs) have been studied for several years. This paper has proposed an approach to analyze the reflectivity of this reflecting grating in two directions. In the method, resonant modal was firstly analyzed with three-dimensional (3-D) finite element method (FEM) using the commercial software COMSOL Multiphysics, which was accurate and be suitable for 2-D PCs structures. With the resonant modal analysis, reflectivity can be obtained. The results show that the reflectivity of the 2-D reflecting grating is 2.2 times higher than 1-D reflecting grating in the x direction and 5.6 times in the y direction. These results demonstrate that the 2-D PCs reflecting grating can be used in SAW resonators to improve their performances. More researches are to be done to apply the 2-D PCs on the SAW resonators.