Abstract: An acoustic wave device includes a first IDT electrode on a first main surface of a piezoelectric layer, and a second IDT electrode on a second main surface of the piezoelectric layer. The first IDT electrode includes first and second electrode fingers. The second IDT electrode includes third and fourth electrode fingers. The first and fourth electrode fingers overlap each other with the piezoelectric layer interposed therebetween. The second and third electrode fingers overlap each other with the piezoelectric layer interposed therebetween. A potential of the first electrode finger and that of the fourth electrode finger are opposite to each other. A potential of the second electrode finger and that of the third electrode finger are opposite to each other.

Abstract: An acoustic wave device includes an Interdigital Transducer (IDT) electrode on a first main surface of a piezoelectric layer, a conductive material layer on a second main surface of the piezoelectric layer, and a dielectric layer provided between the piezoelectric layer and the conductive material layer. When a film thickness of the piezoelectric layer is represented as Tp[?] and a film thickness of the dielectric layer is represented as Td[?], the Formula (1) is satisfied or Td=0, where ? is a wavelength determined by an electrode finger pitch of the IDT electrode, and Tp[?]?about 0.025: Td[?]??2.369×(Tp[?])4 +2.721×(Tp[?])3 ?1.049×(Tp[?])2 +0.076×(Tp[?]) +0.095??Formula (1).

Abstract: In an acoustic wave device, a first IDT electrode is provided on a first main surface of a piezoelectric film, and a second IDT electrode is provided on a second main surface of the piezoelectric film. A crystal c-axis of the piezoelectric film is tilted with respect to a direction normal to the first and second main surfaces. A direction of an electric field generated between a busbar of a comb-shaped electrode and end portions of electrode fingers facing the busbar in the first IDT electrode and a direction of an electric field generated between a busbar and end portions of electrode fingers facing the busbar in the second IDT electrode are opposite directions.

Abstract: An acoustic wave device includes a support including a support substrate, a piezoelectric layer provided on the support and including a first principal surface and a second principal surface facing each other, a first IDT electrode provided on the first principal surface, and a second IDT electrode provided on the second principal surface. The second IDT electrode is embedded in the support. At least one cavity is provided in a periphery of a portion of the support in which electrode fingers of the second IDT electrode is embedded.

Abstract: An acoustic wave device includes a support substrate including a main surface including first and second regions adjacent to each other in a plan view; a multilayer body including an intermediate layer in the first region of the support substrate and a piezoelectric layer on the intermediate layer, and including a side surface; an IDT electrode on the piezoelectric layer of the multilayer body; and an insulating film in the second region of the support substrate to cover the side surface of the multilayer body. An angle defined between the main surface of the support substrate and the side surface of the multilayer body is a tilt angle, and the side surface of the multilayer body includes portions having different tilt angles at a portion covered with the insulating film.

Abstract: An acoustic wave device includes an energy confinement layer, a piezoelectric film, and an IDT electrode laminated on a support substrate. Acoustic velocity adjustment films are at least partially provided between the piezoelectric film and the support substrate and are made of a material different from that of the piezoelectric film.

Abstract: An acoustic wave device includes a support substrate and first and second resonant sections adjacent to each other on the support substrate. Each of the first and second resonant sections includes a piezoelectric thin film, an IDT electrode on the piezoelectric thin film, and a support layer surrounding the piezoelectric thin film in a plan view of the acoustic wave device. The support layer has a different linear expansion coefficient from the piezoelectric thin film. The piezoelectric thin film in the first resonant section and the piezoelectric thin film in the second resonant section are divided by the support layer between the resonant section and the resonant section.

Abstract: An acoustic wave device includes a supporting substrate, an acoustic reflection film the supporting substrate, a piezoelectric thin film on the acoustic reflection film, and an interdigital transducer electrode the piezoelectric thin film. The acoustic reflection film includes acoustic impedance layers including therein first, second, third, and fourth low acoustic impedance layers and first, second, and third high acoustic impedance layers. The acoustic reflection film includes a first acoustic impedance layer and a second acoustic impedance layer, the first and second acoustic impedance layers each being one of the acoustic impedance layers, and the second acoustic impedance layer has an arithmetic average roughness different from that of the first acoustic impedance layer.

Abstract: An acoustic wave device includes a support substrate including a main surface including first and second regions adjacent to each other in a plan view; a multilayer body including an intermediate layer in the first region of the support substrate and a piezoelectric layer on the intermediate layer, and including a side surface; an IDT electrode on the piezoelectric layer of the multilayer body; and an insulating film in the second region of the support substrate to cover the side surface of the multilayer body. An angle defined between the main surface of the support substrate and the side surface of the multilayer body is a tilt angle, and the side surface of the multilayer body includes portions having different tilt angles at a portion covered with the insulating film.

Abstract: An acoustic wave device includes an IDT electrode provided on a piezoelectric substrate. The IDT electrode includes a crossing area including a central area, and first and second low-acoustic-velocity areas on both sides in a direction perpendicular or substantially perpendicular to an acoustic wave propagating direction. First and second high-acoustic-velocity areas are provided outside the first and second low-acoustic-velocity areas. Mass adding films are laminated in respective portions of first and second electrode fingers, the respective portions being positioned in the first and second low-acoustic-velocity areas. In at least one of the mass adding films, a width of a first end portion and a width of a second end portion are narrower than a width of a central portion, and a protruding portion protrudes from at least one of the first and second end portions.

Abstract: An acoustic wave device includes a supporting substrate, an acoustic reflection film the supporting substrate, a piezoelectric thin film on the acoustic reflection film, and an interdigital transducer electrode the piezoelectric thin film. The acoustic reflection film includes acoustic impedance layers including therein first, second, third, and fourth low acoustic impedance layers and first, second, and third high acoustic impedance layers. The acoustic reflection film includes a first acoustic impedance layer and a second acoustic impedance layer, the first and second acoustic impedance layers each being one of the acoustic impedance layers, and the second acoustic impedance layer has an arithmetic average roughness different from that of the first acoustic impedance layer.

Abstract: An acoustic wave device includes an IDT electrode provided on a piezoelectric substrate. The IDT electrode includes a crossing area including a central area, and first and second low-acoustic-velocity areas on both sides in a direction perpendicular or substantially perpendicular to an acoustic wave propagating direction. First and second high-acoustic-velocity areas are provided outside the first and second low-acoustic-velocity areas. Mass adding films are laminated in respective portions of first and second electrode fingers, the respective portions being positioned in the first and second low-acoustic-velocity areas. In at least one of the mass adding films, a width of a first end portion and a width of a second end portion are narrower than a width of a central portion, and a protruding portion protrudes from at least one of the first and second end portions.