Keywords: Surface acoustic wave, Weighted waveguides, Piezoelectric, Phononic crystal

Phononic crystals (PnCs) composed of periodic elastic materials prove to have a property of band gaps. With the unique property, PnCs show potential for applications such as elastic filters, couplers, resonators and waveguides. Much research had been conducted with the bulk acoustic waves based on the two-dimensional (2D) PnCs.

The designs were straight waveguides with various widths, waveguides with a stub, waveguide with hollow cylinders and a coupler of joined parallel waveguides. In contrast, research of waveguides based on PnCs for surface acoustic waves (SAW) had less progress. Besides, most of the previous research of waveguides was based on the defect PnCs, more investigations on other SAW waveguides were awaited.

Researchers from the Institute of Acoustics of the Chinese Academy of Sciences and Santai Crystal Electronic propose a new structure of weighted waveguide for SAW based on 2D piezoelectric PnCs, which has different lattice constants in the x and y direction. It proves useful for the application of 2D piezoelectric PnCs in the SAW devices such as resonators and sensors.

Transmission of PnCs with different lattice constants in two directions are respectively analyzed with the commercial software COMSOL Multiphysics and post-processing with Matlab. Comparing the transmission of common PnCs, the transmission of weighted waveguide has shown separation of the band gap and band pass in the x direction and the y direction (see Fig. 1). And thus, this weighted waveguide can be used as the waveguides in a special direction. The distribution of the acoustic field (see Fig. 2) is also confirmed that this structure can be used as the waveguides for the SAW.

The research was supported by the National Natural Science Foundation of China (11174318, 11304346), National High Technology Research and Development Program (863 Program) (SS2013AA041103), Beijing Municipal Science and Technology Commission Project (Z141100003814016) and Tianjin Municipal Science and Technology Commission Project (13RCHZGX01093).

Fig.1 The model used in the calculation (Image by TIAN).

Fig.2 (a) The transmission with the ratio of 1      Fig.2 (b) The transmission with the ratio of 5

Fig.2 Transmission of the model (Image by TIAN).

Fig. 3 (a) The acoustic filed on the surface at 300MHz

Fig. 3 (b) The acoustic filed on the surface at 400MHz

Fig.3 The acoustic field extracted on the surface (Image by TIAN).

References:

TIAN Yahui, LI Honglang, TIAN Wenjia, KE Yabing, CHEN Jinling, HE Shitang. A Weighted Waveguide for Surface Acoustic Waves Based on Two-dimensional Piezoelectric Phononic Crystals. Proceedings of the 2014 Symposium on Piezoelectricity, Acoustic Waves and Device Applications (pp. 375-378, November 2014).

Contact:

TIAN Yahui

Institute of Acoustics, Chinese Academy of Sciences, 100190 Beijing, China

Email: tianyahui@mail.ioa.ac.cn or yahuitian@yeah.net