An acoustic wave device includes an electrode finger on a principal surface of a piezoelectric substrate and extending in a Y-axis direction. In the acoustic wave device, an acoustic wave velocity is distributed in an order of an intermediate velocity, a low velocity, and a high velocity from a center of the electrode finger toward outer side portions in the Y-axis direction. The acoustic wave device further includes a dielectric between the piezoelectric substrate and a tip-end portion of the electrode finger. An end surface of the dielectric in the Y-axis direction includes first and second side surfaces. A tilt angle of the first side surface is smaller than a tilt angle of the second side surface.

A longitudinally coupled resonator acoustic wave filter including IDT electrodes including a first IDT electrode and a second IDT electrode, and first and second reflectors, in which the IDT electrodes have respective hot-side comb-shaped electrodes and respective ground-side comb-shaped electrodes, the hot-side comb-shaped electrodes of the first IDT electrodes are electrically connected to at least one of the first and second reflectors, the second IDT electrodes are between the IDT electrode and the first reflector and between the IDT electrode and the second reflector respectively, the hot-side comb-shaped electrodes of the IDT electrodes are connected to one of an input end and an output end, and the hot-side comb-shaped electrodes of the IDT electrodes are connected to the other of the input end and the output end.

A acoustic wave resonator comprises a piezoelectric substrate and a plurality of interdigital transducer (IDT) electrodes disposed on the piezoelectric substrate, the plurality of IDT electrodes formed of a mixture of tungsten and chromium to provide for reduction in size and increase in quality factor of the acoustic wave resonator.

An elastic wave device includes a piezoelectric film, a high acoustic velocity member, a low acoustic velocity film located between the piezoelectric film and the high acoustic velocity member and through which an elastic wave propagates at a lower acoustic velocity than an elastic wave that propagates through the piezoelectric film, and an interdigital transducer electrode including electrode fingers separated from each other and disposed side by side in a first direction. At least one of the electrode fingers includes a first metal layer including first and second main body portions. A recessed portion is located in a central region in the first direction of the electrode finger and is recessed in the thickness direction of the piezoelectric film. A protrusion portion protrudes from at least a portion of the first main body portion in the first direction.

A surface acoustic wave device has a piezoelectric substrate having a cut angle (e.g., the piezoelectric angle is cut so as to have a crystal orientation) that allows the surface acoustic wave device to operate as a longitudinally leaky surface acoustic wave device that confines the acoustic wave energy within the piezoelectric substrate and that has less propagation attenuation and a higher electromechanical coupling coefficient k.sup.2.

An elastic wave device includes a piezoelectric substrate, elastic wave resonators on or in the piezoelectric substrate, and a dielectric film disposed on the piezoelectric substrate and covering the elastic wave resonators. The elastic wave resonators includes respective IDT electrodes on the piezoelectric substrate. When a wavelength specified by an electrode finger pitch of the IDT electrode is denoted as λ, at least two of the elastic wave resonators have the different wavelengths. In two of the elastic wave resonators having different wavelengths, a film thickness of the IDT electrode in the elastic wave resonator having the longer wavelength is not greater than that of the IDT electrode in the elastic wave resonator having the shorter wavelength. Film thicknesses of the IDT electrodes in at least two of the elastic wave resonators are different from each other. The elastic wave device utilizes a Rayleigh wave.

A surface acoustic wave (SAW) device having a high electromechanical coupling coefficient based on double-layer electrodes and a preparation method thereof. A structure of the SAW device includes a Cu electrode, a piezoelectric film and an Al electrode on a substrate in sequence. A signal terminal of the Cu electrode is opposite to a ground terminal of the Al electrode. A ground terminal of the Cu electrode is opposite to a signal terminal of the Al electrode. Since Sezawa wave mode that is adopted is formed by coupling film thickness vibration and transverse vibration, a longitudinal electric field (in a direction of thickness of a film) and a transverse electric field (in a propagation direction of SAW) are excited through the double-layer electrodes so that the electromechanical coupling coefficient of the SAW device is improved by changing a coupling pattern between the electric fields and the piezoelectric film.

A surface acoustic wave device according to the present disclosure includes a support substrate; an intermediate layer laminated on the support substrate; a piezoelectric layer laminated on the intermediate layer; and an IDT electrode formed on the piezoelectric layer, an Euler angle of the support substrate is (−45°±10°, −54°±10°, 180°±30°) and an Euler angle of the piezoelectric layer is (0°±5°, 112.5°±22.5°, 0°±5°) or (0°±5°, −67.5°±22.5°, 0°±5°).

When a current flowing in a series circuit including an equivalent resistance, an equivalent inductor, and an equivalent capacitance in an electric equivalent circuit of a specific resonator in each filter is defined as an acoustic path current, under conditions that a phase of an acoustic path current of a first transmission filter at a side of a common terminal at a frequency within a first transmission band is represented as θ1.sub.Tx, a phase of an acoustic path current of the first transmission filter at the side of the common terminal at a frequency within a second transmission band is represented as θ2.sub.Tx, a phase of an acoustic path current of a first reception filter at the side of the common terminal at a frequency within the first transmission band is represented as θ1.sub.Rx, and a phase of an acoustic path current of the first reception filter at the side of the common terminal at a frequency within the second transmission band is represented as θ2.sub.Rx, a multiplexer satisfies a first condition: |(2.Math.θ1.sub.Tx−θ2.sub.Tx)−(2.Math.θ1.sub.Rx−θ2.sub.Rx)|=180°±90°, or a second condition: |(2.Math.θ2.sub.Tx−θ1.sub.Tx)−(2.Math.θ2.sub.Rx−θ1.sub.Rx)|=180°±90°.

A surface acoustic wave (SAW) device and methods of making the same are disclosed. The surface acoustic wave device includes a piezoelectric layer coupled to a high acoustic velocity layer at a first surface of the piezoelectric layer. At least one transducer is provided over a second surface of the piezoelectric layer. The at least one transducer comprises a plurality of IDT electrodes that are formed from a substantially two-dimensional (2D) conductive material and configured to propagate a surface acoustic wave having an operating wavelength along the piezoelectric layer.