Coupled-mode analysis of Love waves in a filter film with periodically corrugated surfaces

Mode coupling of Love waves in an orthotropic thin film having periodically corrugated surfaces over an isotropic elastic half space is considered. Six modes are coupled by both surfaces by means of three simultaneous resonant conditions. On the basis of the weakness of the corrugations, the method of multiple scales is used to derive the coupled-mode equations. These equations together with relevant boundary conditions form a two-point boundary-value problem, which is solved numerically. The filter frequency response of a corrugated film designed as a stop-band filter is calculated. Enhanced filter characteristics are achieved when tapered corrugations are imposed. A narrow pass-band filter is also designed. Its high quality factor presents the fascinating features that might be realized by including the periodic corrugations in the design of SAW devices.<
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