Aspects of this disclosure relate to an acoustic wave device with transverse mode suppression. The acoustic wave device can include a piezoelectric layer, an interdigital transducer electrode, a temperature compensation layer, and a multi-layer mass loading strip. The mass loading strip has a density that is higher than a density of the temperature compensation layer. The mass loading strip can overlap edge portions of fingers of the interdigital transducer electrode. The mass loading strip can include a first layer for adhesion and a second layer for mass loading. The mass loading strip can suppress a transverse mode.

An acoustic wave device includes a piezoelectric substrate, and an IDT electrode provided on the piezoelectric substrate. The IDT electrode includes an overlap region where first and second electrode fingers overlap each other in a first direction. The overlap region includes a central region located in a substantially central portion of the overlap region with respect to a second direction. The central region includes a low acoustic velocity portion with an acoustic velocity less than the acoustic velocity in another portion. The overlap region includes first and second low acoustic velocity regions. The first and second low acoustic velocity regions are respectively located on first- and-second-busbar sides from the central region. The IDT electrode includes first and second high acoustic velocity regions. The first and second high acoustic velocity regions are respectively located outside the first and second low acoustic velocity regions with respect to the second direction.

An elastic wave device includes an interdigital transducer electrode, a dielectric film, and a frequency adjustment film are disposed on a LiNbO.sub.3 substrate. When Euler Angles of the LiNbO.sub.3 substrate are within a range of about 0??5?, within a range of about ??1.5?, within a range of about 0??10?, the interdigital transducer electrode includes a main electrode, a film thickness of the main electrode normalized by a wavelength determined in accordance with an electrode finger pitch of the interdigital transducer electrode is denoted as T, and a density ratio of a material of the main electrode to Pt is denoted as r, the film thickness of the main electrode and ? of the Euler Angles satisfy ?=?0.05?/(T/r?0.04)+31.35?.

A filter with reduced plate modes is specified. Thereto, the filter has a transducer system (WS) with two or more electroacoustic split transducers (TW) connected in parallel that replace a conventional transducer (W). The static capacity of the transducer system corresponds to the sum of the static capacities of the split transducers. Each split transducer has a lower electroacoustic coupling of a desired mode than the transducer system. The transducer system has an electroacoustic coupling of a plate mode corresponding to the electroacoustic coupling of the plate mode of a split transducer.

An acoustic wave resonator includes: a piezoelectric substrate; and an IDT located on the piezoelectric substrate and including a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes including a grating electrode exciting an acoustic wave and a bus bar to which the grating electrode is connected, wherein an anisotropy coefficient in a cross region where the grating electrodes of the pair of comb-shaped electrodes cross each other is positive; an anisotropy coefficient in a gap region located between a tip of the grating electrode of one of the pair of comb-shaped electrodes and the bus bar of the other is less than the anisotropy coefficient in the cross region, and an acoustic velocity of an acoustic wave propagating through the gap region is equal to or less than an acoustic velocity of an acoustic wave propagating through the cross region at an antiresonant frequency.

Aspects of this disclosure relate to an acoustic wave resonator with hyperbolic mode suppression. The acoustic wave resonator can include a piezoelectric layer, an interdigital transducer electrode, a temperature compensation layer, and a mass loading strip. The mass loading strip can be a conductive strip. The mass loading strip can overlap edge portions of fingers of the interdigital transducer electrode. A layer of the mass loading strip can have a density that is at least as high as a density of a material of the interdigital transducer electrode. The material of the interdigital transducer can impact acoustic properties of the acoustic wave resonator.

In an acoustic wave device, a resonator including an IDT electrode and a portion of a piezoelectric substrate includes a middle region, a first gap region, a second gap region, a first edge region, a second edge region, a first intermediate region, and a second intermediate region. The first intermediate region is located between the middle region and the first edge region. The second intermediate region is located between the middle region and the second edge region. An acoustic wave velocity in the first intermediate region and in the second intermediate region are lower than an acoustic wave velocity in the middle region and higher than an acoustic wave velocity in the first edge region and an acoustic wave velocity in the second edge region.

An acoustic wave resonator includes: a piezoelectric substrate; an IDT located on the piezoelectric substrate and including comb-shaped electrodes facing each other, each of the comb-shaped electrodes including: electrode fingers exciting an acoustic wave; and a bus bar to which the electrode fingers are connected; a dielectric film located on the piezoelectric substrate in an overlap region, where the electrode fingers of one of the comb-shaped electrodes and the electrode fingers of the other overlap, so as to cover the electrode fingers; and an additional film located on the dielectric film in the overlap region and having a density greater than that of the dielectric film, and of which a film thickness in edge regions corresponding to both edges of the overlap region in an extension direction of the electrode fingers is greater than a film thickness in a central region sandwiched between the edge regions in the overlap region.

An acoustic wave device includes a piezoelectric body layer having a crystal axis and an IDT electrode on the piezoelectric body layer. When an acoustic wave propagation direction is a first direction and an orthogonal or substantially orthogonal direction is a second direction, the crystal axis of the piezoelectric body layer is inclined in the second direction with respect to a thickness direction. The IDT electrode includes first and second busbars that oppose each other, and first and second electrode fingers and each including one end connected to any one of the first and second busbars. A region where the adjacent electrode fingers overlap each other in the first direction is a cross region which includes a central region positioned on a center side in the second direction, and first and second edge regions that oppose each other with the central region interposed therebetween in the second direction.

An acoustic wave device includes a piezoelectric substrate and an interdigital transducer disposed on the piezoelectric substrate, the interdigital transducer including a center region, first and second edge regions, and first and second gap regions, a temperature compensation layer covering the interdigital transducer, and a floating metal layer buried in the temperature compensation layer or disposed on top of the temperature compensation layer. The floating metal layer includes a plurality of floating metal blocks spaced apart from each other and overlapping at least the first and second edge regions of the interdigital transducer.