Abstract: An acoustic wave device includes an energy confinement layer, a piezoelectric layer made of Y-cut X-propagation lithium tantalate having a cut angle in a range from about ?10° to about 65°, and an IDT electrode. Electrode fingers of the IDT electrode include an Al metal layer and a high acoustic impedance metal layer having a Young's modulus equal to or more than about 200 GPa and an acoustic impedance higher than Al. The high acoustic impedance metal layer is closer to the piezoelectric layer than the Al metal layer. A wavelength specific film thickness tLT of the piezoelectric layer is expressed by tLT?1?. The total of normalized film thicknesses obtained by normalizing the film thickness of each layer of the electrode finger by a density and Young's modulus of the Al metal layer satisfies T?0.1125tLT+0.0574.

Abstract: An acoustic wave device in which a cavity defining an acoustic reflector is formed on a first main surface side of a substrate, an excitation portion is structured above the cavity in a manner that a first electrode, a piezoelectric thin film, and a second electrode are laminated, and a periodic pattern is provided in a normal direction of a side of the excitation portion on at least one of a first extraction electrode and a second extraction electrode.

Abstract: An acoustic wave device includes a support substrate, a piezoelectric film, a functional electrode, and a support. The support substrate includes a cavity. The piezoelectric film is provided on the support substrate to cover the cavity. The functional electrode is provided on the piezoelectric film to overlap the cavity when viewed in a plan view. The support is in the cavity of the support substrate to support the piezoelectric film. The functional electrode includes electrodes arranged in a direction crossing the thickness direction of the piezoelectric film. The electrodes include a first electrode and a second electrode. The first electrode and the second electrode oppose each other in a direction crossing the thickness direction of the piezoelectric film and are connected to different potentials. Adjacent ones of the electrodes overlap each other in a direction orthogonal to a longitudinal direction of the first electrode.

Abstract: An acoustic wave device includes a support substrate, a piezoelectric layer, and an IDT electrode. The piezoelectric layer is directly or indirectly provided on the support substrate. The IDT electrode includes a plurality of electrode fingers and is provided on a main surface of the piezoelectric layer. The thickness of the piezoelectric layer is about 1? or less when a wavelength of an acoustic wave determined by an electrode finger period of the IDT electrode is defined as ?. The support substrate is an A-plane sapphire substrate.

Abstract: An acoustic wave device uses a longitudinal acoustic wave, and includes a piezoelectric layer including first and second principal surfaces opposite to each other, an IDT electrode directly or indirectly on the first principal surface, and a high acoustic velocity member directly or indirectly on the second principal surface and including a 4H-type or 6H-type crystal polytype silicon carbide.

Abstract: An acoustic wave device includes a high-acoustic-velocity layer, a piezoelectric layer made of lithium tantalate, and an interdigital transducer electrode that are successively laminated. An acoustic velocity of a bulk wave propagating in the high-acoustic-velocity layer is higher than an acoustic velocity of an acoustic wave propagating in the piezoelectric layer, and an acoustic velocity Vsub of a fast transversal bulk wave propagating in the high-acoustic-velocity layer satisfies Vsh0?Vsub?Vsp with respect to an acoustic velocity Vsh0 of an SH0 mode and an acoustic velocity Vsp of a mode becoming a spurious of which acoustic velocity is not lower than the acoustic velocity of the SH0 mode, wherein the acoustic velocity Vsh0 and the acoustic velocity Vsp is obtained from Eq. (1).

Abstract: An acoustic wave device includes a support substrate, a silicon nitride film stacked on the support substrate, a silicon oxide film stacked on the silicon nitride film, a piezoelectric body stacked on the silicon oxide film and made of lithium tantalite, and an IDT electrode provided on one main surface of the piezoelectric body. For a wavelength normalized film thickness of the piezoelectric body, an Euler angle of the piezoelectric body, a wavelength normalized film thickness of the silicon nitride film, a wavelength normalized film thickness of the silicon oxide film, and a wavelength normalized film thickness of the IDT electrode, values are set so that at least one of a response intensity of a first higher order mode, corresponding to the response intensity of a second higher order mode, and of a response intensity of a third higher mode is greater than about ?2.4.

Abstract: An acoustic wave device includes a support substrate including silicon, a piezoelectric layer provided directly or indirectly on the support substrate, and an interdigital transducer (IDT) electrode provided on the piezoelectric layer. When a wavelength defined by an electrode finger pitch of the IDT electrode is ?, a thickness of the piezoelectric layer is about 1? or less. VL, which is an acoustic velocity of a longitudinal wave component of a bulk wave propagating through the piezoelectric layer, satisfies Unequal Equation (2) below in relation to an acoustic velocity VSi-1 determined by Equation (1) below: VSi-1=(V2)1/2 (m/sec)??Equation (1), VSi-1?VL??Unequal Equation (2), V2 in Equation (1) is a solution of Equation (3), and Ax3+Bx2+Cx+D=0??Equation (3).

Abstract: A multiplexer includes N acoustic wave filters each including one end connected in common and having a different pass band, in which when the N acoustic wave filters are in order from a side of a lower frequency of the pass band, at least one n-th acoustic wave filter among the N acoustic wave filters excluding an acoustic wave filter having the highest frequency of the pass band includes one or more acoustic wave resonators including a support substrate, a silicon nitride film laminated on the support substrate, a silicon oxide film laminated on the silicon nitride film, a piezoelectric body laminated on the silicon oxide film, and an IDT electrode provided on the piezoelectric body. All acoustic wave filters having a pass band in a higher frequency than a frequency of a pass band of the n-th acoustic wave filter satisfy fh1_t(n)>fu(m) or fh1_t(n)<fl(m).

Abstract: An acoustic wave device includes a piezoelectric film stacked directly on or indirectly above a support substrate; and an IDT electrode on the piezoelectric film and including an intersecting region in which first and second electrode fingers overlap with each other in an acoustic wave propagation direction, the intersecting region includes a central region in a direction in which the first and second electrode fingers extend and first and second edge regions on sides outside the central region, acoustic velocities in the first and second edge regions are lower than an acoustic velocity in the central region, a thickness Ht in the central region is different from thicknesses He in the first and second edge regions, and at least either of Ht and He is not more than about 1?, where ? is a wavelength which is determined by an electrode finger pitch of the IDT electrode.

Abstract: An acoustic wave device includes an energy confinement layer, a piezoelectric layer made of Y-cut X-propagation lithium tantalate having a cut angle in a range from about ?10° to about 65°, and an IDT electrode. Electrode fingers of the IDT electrode include an Al metal layer and a high acoustic impedance metal layer having a Young's modulus equal to or more than about 200 GPa and an acoustic impedance higher than Al. The high acoustic impedance metal layer is closer to the piezoelectric layer than the Al metal layer. A wavelength specific film thickness tLT of the piezoelectric layer is expressed by tLT?1?. The total of normalized film thicknesses obtained by normalizing the film thickness of each layer of the electrode finger by a density and Young's modulus of the Al metal layer satisfies T?0.1125tLT+0.0574.

Abstract: An acoustic wave device includes a support substrate, a piezoelectric film, a functional electrode, and a support. The support substrate includes a cavity. The piezoelectric film is provided on the support substrate to cover the cavity. The functional electrode is provided on the piezoelectric film to overlap the cavity when viewed in a plan view. The support is in the cavity of the support substrate to support the piezoelectric film. The functional electrode includes electrodes arranged in a direction crossing the thickness direction of the piezoelectric film. The electrodes include a first electrode and a second electrode. The first electrode and the second electrode oppose each other in a direction crossing the thickness direction of the piezoelectric film and are connected to different potentials. Adjacent ones of the electrodes overlap each other in a direction orthogonal to a longitudinal direction of the first electrode.

Abstract: An acoustic wave device in which a cavity defining an acoustic reflector is formed on a first main surface side of a substrate, an excitation portion is structured above the cavity in a manner that a first electrode, a piezoelectric thin film, and a second electrode are laminated, and a periodic pattern is provided in a normal direction of a side of the excitation portion on at least one of a first extraction electrode and a second extraction electrode.

Abstract: An acoustic wave device includes a support substrate, an acoustic reflection film on the support substrate, a piezoelectric layer on the acoustic reflection film, the piezoelectric layer including first and second primary surfaces, and first and second flat-plate electrodes on the first and second primary surfaces of the piezoelectric layer. The acoustic reflection film includes high acoustic impedance layers and low acoustic impedance layers alternately stacked together. At least one layer of the high acoustic impedance and low acoustic impedance layers is a stack of layers of first and second materials having equal or substantially equal acoustic impedances for at least one of longitudinal acoustic impedance and transversal acoustic impedance. The interface between the layers of first and second materials has irregularities.

Abstract: An acoustic wave device includes a support substrate, a piezoelectric layer, and an IDT electrode. The piezoelectric layer is directly or indirectly provided on the support substrate. The IDT electrode includes a plurality of electrode fingers and is provided on a main surface of the piezoelectric layer. The thickness of the piezoelectric layer is about 1? or less when a wavelength of an acoustic wave determined by an electrode finger period of the IDT electrode is defined as ?. The support substrate is an A-plane sapphire substrate.

Abstract: An acoustic wave device uses a longitudinal acoustic wave, and includes a piezoelectric layer including first and second principal surfaces opposite to each other, an IDT electrode directly or indirectly on the first principal surface, and a high acoustic velocity member directly or indirectly on the second principal surface and including a 4H-type or 6H-type crystal polytype silicon carbide.

Abstract: An acoustic wave device includes a high-acoustic-velocity layer, a piezoelectric layer made of lithium tantalate, and an interdigital transducer electrode that are successively laminated. An acoustic velocity of a bulk wave propagating in the high-acoustic-velocity layer is higher than an acoustic velocity of an acoustic wave propagating in the piezoelectric layer, and an acoustic velocity Vsub of a fast transversal bulk wave propagating in the high-acoustic-velocity layer satisfies Vsh0?Vsub?Vsp with respect to an acoustic velocity Vsh0 of an SH0 mode and an acoustic velocity Vsp of a mode becoming a spurious of which acoustic velocity is not lower than the acoustic velocity of the SH0 mode, wherein the acoustic velocity Vsh0 and the acoustic velocity Vsp is obtained from Eq. (1).

Abstract: An acoustic wave device includes a support substrate including silicon, a piezoelectric layer provided directly or indirectly on the support substrate, and an interdigital transducer (IDT) electrode provided on the piezoelectric layer. When a wavelength defined by an electrode finger pitch of the IDT electrode is ?, a thickness of the piezoelectric layer is about 1? or less. VL, which is an acoustic velocity of a longitudinal wave component of a bulk wave propagating through the piezoelectric layer, satisfies Unequal Equation (2) below in relation to an acoustic velocity VSi-1 determined by Equation (1) below: VSi-1=(V2)1/2 (m/sec)??Equation (1), VSi-1?VL??Unequal Equation (2), V2 in Equation (1) is a solution of Equation (3), and Ax3+Bx2+Cx+D=0??Equation (3).

Abstract: An acoustic wave device includes a support substrate, an acoustic reflection film on the support substrate, a piezoelectric layer on the acoustic reflection film, the piezoelectric layer including first and second primary surfaces, and first and second flat-plate electrodes on the first and second primary surfaces of the piezoelectric layer. The acoustic reflection film includes high acoustic impedance layers and low acoustic impedance layers alternately stacked together. At least one layer of the high acoustic impedance and low acoustic impedance layers is a stack of layers of first and second materials having equal or substantially equal acoustic impedances for at least one of longitudinal acoustic impedance and transversal acoustic impedance. The interface between the layers of first and second materials has irregularities.

Abstract: A multiplexer includes N acoustic wave filters each including one end connected in common and having a different pass band, in which when the N acoustic wave filters are in order from a side of a lower frequency of the pass band, at least one n-th acoustic wave filter among the N acoustic wave filters excluding an acoustic wave filter having the highest frequency of the pass band includes one or more acoustic wave resonators including a support substrate, a silicon nitride film laminated on the support substrate, a silicon oxide film laminated on the silicon nitride film, a piezoelectric body laminated on the silicon oxide film, and an IDT electrode provided on the piezoelectric body. All acoustic wave filters having a pass band in a higher frequency than a frequency of a pass band of the n-th acoustic wave filter satisfy fhl_t(n)>fu(m) or fhl_t(n)<fl(m).