Bleustein-Gulyaev-Shimizu Wave Propagating under Metallic Gratings of Finite Thickness

The discrete Green function theory, which takes the mass-loading effect into consideration, is developed, and the propagation and excitation characteristics of a Bleustein-Gulyaev-Shimizu wave (BGSW) under metallic gratings of finite thickness are discussed. Acoustic fields in the grating electrodes are expressed as a sum of analytical solutions, while those in a substrate, as the effective acoustic impedance matrix. The effective permittivity for the grating structure, which gives the discrete Green function, is derived by minimising a functional defined by the acoustic fields at the boundary. Velocity dispersion of BGSW propagating on Al-grating/PZT-5H and Au-grating/PZT-5H structures is shown, and the mass-loading effect on the BGSW propagation and excitation is discussed.