Precise coupling-of-modes simulation of surface transverse wave devices for frequency control applications

The paper proposes a precise simulation method for devices employing surface transverse waves (STWs) which propagate under grating structure and possess strong dispersive nature. The method is based on the coupling-of-modes (COM) theory, where four parameters required for the analysis, i.e., static capacitance, and self-coupling, mutual-coupling and transduction coefficients are determined as a function of frequency by the discrete Green function theory. The method was applied to the simulation STW resonator filters on quartz employing metallic gratings. The result was in good agreement with experiments, and showed that the passband shape as well as the resonance frequency are most dependent on the thickness and width of grating electrodes. This indicates that STWs on quartz with weak piezoelectric coupling are substantially guided close to the surface by mass-loading effect of gratings