Highly tunable Fabry-Perot resonators using piezoelectric phononic crystals

Theoretical and experimental analyses of piezoelectric stacks submitted to periodical electrical boundary conditions via electrodes, are conducted. These structures are shown to exhibit Bragg band gaps which are switched on or off by setting electrodes in short or open circuit. Band gap frequency width is determined by electromechanical coupling coefficient. This property is used to design a Fabry-Perot cavity the length of which is delimited by two periodical piezoelectrical stacks. Tunability of cavity resonance is obtained by varying cavity length i.e. by shifting spatially short circuit boundary conditions in the stacks. 36% tuning of resonance and antiresonance frequencies with almost constant resonator electromechanical coupling coefficient of 40% are theoretically predicted for PZT.