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.

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 device (5) is provided using a layered substrate system with a special material and a special cut of a piezoelectric thin film (4) selected for utilizing Rayleigh mode. The proper choice of the material and the cut of the piezoelectric thin film leads to a low velocity of the excited wave mode, which allows the usage of smaller devices without deteriorating other performance parameters according to specifications.

A surface acoustic wave device (5) is provided using a layered substrate system with a special material and a special cut of a piezoelectric thin film (4) selected for utilizing Rayleigh mode. The proper choice of the material and the cut of the piezoelectric thin film leads to a low velocity of the excited wave mode, which allows the usage of smaller devices without deteriorating other performance parameters according to specifications.

Provided is an acoustic wave device that uses a plate wave. The acoustic wave device includes a piezoelectric film and a first resonator and a second resonator each including an IDT electrode located on an upper surface of the piezoelectric film. The thickness of the piezoelectric film is smaller than twice the period of the electrode fingers of the IDT electrodes. The duty of the electrode fingers of the first resonator and the duty of the electrode fingers of the second resonator are different from each other.

Provided is an acoustic wave device that uses a plate wave. The acoustic wave device includes a piezoelectric film and a first resonator and a second resonator each including an IDT electrode located on an upper surface of the piezoelectric film. The thickness of the piezoelectric film is smaller than twice the period of the electrode fingers of the IDT electrodes. The duty of the electrode fingers of the first resonator and the duty of the electrode fingers of the second resonator are different from each other.

Disclosed is a device that includes a crystalline substrate and a patterned aluminum-based material layer disposed onto the crystalline substrate. The patterned aluminum-based material layer has a titanium-alloyed surface. A titanium-based material layer is disposed over select portions of the titanium-alloyed surface. In an exemplary embodiment, the patterned aluminum-based material layer forms a pair of interdigitated transducers to provide a surface wave acoustic (SAW) device. The SAW device of the present disclosure is usable to realize SAW-based filters for wireless communication equipment.

A transmission filter is arranged in a first filter region and has one or more acoustic wave resonators, a plurality of terminal electrodes, and a plurality of wires. A reception filter is arranged in a second filter region and has one or more acoustic wave resonators, a plurality of terminal electrodes, and a plurality of wires. The first filter region and the second filter region are arranged adjacently to each other and have at least sides constituting a pair and opposing to each other. At least either one of the first filter region and the second filter region has no wire extending along one side in a forbidden region that is defined by a width including a terminal electrode nearest to the one side, along the one side and over the one side opposing to the other filter region.