Acoustic wave filter based on periodically poled lithium niobate

We present results on the development of an acoustic bandpass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of Periodically Poled Transducers (PPT) operating in the range 20 - 650 MHz has been achieved on a 3" 500 μm thick wafer. This kind of transducer enables to excite elliptical as well as longitudinal modes, yielding phase velocity of about 3800 and 6500 m.s^-1 respectively. We propose then a new type of acoustic bandpass filter based on the use of PPTs instead of classical IDTs. The design and the fabrication of such a filter are presented as well as the experimental measurements. Finally we demonstrate the feasibility of such a PPTs-based filter.