Acoustic wave device and filter device

Abstract

An acoustic wave device includes a piezoelectric layer including a first main surface and a second main surface that face away from each other, a first electrode on the first main surface of the piezoelectric layer, and a second electrode on the second main surface of the piezoelectric layer, that faces the first electrode with the piezoelectric layer therebetween. The piezoelectric layer includes a first region and a second region in which a polarization direction is reversed from a polarization direction in the first region. The first region and the second region are cyclically arranged in a direction orthogonal to a thickness direction of the piezoelectric layer. The acoustic wave device further includes mass-addition films provided on the first electrode and cyclically positioned in a direction in which the first region and the second region are arranged.

Dependencies are inferred from the claim text.