Plate wave stop-bands in periodically poled lithium niobate.

The dispersion curves of four lowest plate acoustic waves (PAWs) in the ZX cut of a periodically poled lithium niobate (PPLN) wafer are computed numerically and investigated experimentally. Experiment is in agreement with simulated dispersion curves. Calculations and measurements reveal the stop-bands in the dispersion curves of the PAW modes in PPLN despite a wafer that has uniform mechanical properties. At a specific wave number, within the frequencies of the stop-bands, the acoustic modes do not propagate.