金属周期構造上の圧電すべり表面波の伝搬特性

概要

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Dispersion relations around at Bragg reflection are derived for Bleustein-Gulyaev wave propagating through periodic metal strips on a piezoelectric surface. Those relations depend upon relative permittivity, electromechanical coupling constant of piezoelectrics, and depend on whether electrodes are electrically insulated (open) or connected (shorted). Numerical calculations demonstrate striking features of the Bleustein-Gulyaev wave dispersion, much differing from those of Rayleigh wave. The optimum metallization ratio of IDT's electrode finger is found to be in a range from 0.6 to 0.7, in contrast to 0.5 of Rayleigh wave. In some range of metallization ratio, upper band curves in the dispersion are convex regardless of the electrical boundary condition, which cannot be predicted by conventional "mixed circuit" model. Trapped mode of Bleustein-Gulyaev wave turns into leaky mode above the upper stopband frequency and below the frequency at which bulk shear wave is to be launched.
東京工芸大学の論文