Acoustic wave resonators, filters and the duplexer

PROBLEM TO BE SOLVED: To provide an acoustic wave resonator which suppresses transverse mode spurious and reduces a loss, a filter and a duplexer.SOLUTION: The acoustic wave resonator comprises: a piezoelectric substrate; and an IDT which is formed on the piezoelectric substrate and in which paired interdigital electrodes oppose each other, each of the interdigital electrodes including a grating electrode which excites an acoustic wave, and a bus bar for connecting the grating electrode. An anisotropy coefficient γ0 in a crossover region 15 where the grating electrodes of the paired interdigital electrodes cross each other, is positive. An anisotropy coefficient γg in a gap region 17 that is positioned between a distal end of the grating electrode of one interdigital electrode and the bus bar of the other interdigital electrode is smaller than the anisotropy coefficient in the crossover region. A sonic velocity Vg of an acoustic wave that is propagated in the gap region is equal to or lower than a sonic velocity Vfa in an anti-resonant frequency of an acoustic wave that is propagated in the crossover region.SELECTED DRAWING: Figure 5