Optimization of a Tunable Piezoelectric Resonator Using Phononic Crystals with Periodic Electrical Boundary Conditions

Piezoelectric phononic crystals with periodic short-circuit conditions exhibit Bragg band gaps. They are used to design a Fabry-Perot cavity. The design of the device enables a modification of cavity length by a spatial shift of electrical boundary conditions. The resonator is thus tunable and a frequency shift is obtained. An analytical model based on a transfer matrix formalism is used to model longitudinal wave propagation inside the structure. Cavity length, phononic crystal and transducer position are optimized to increase resonance and antiresonance frequency shifts as well as coupling coefficient. Numerical and experimental results are presented and discussed.