An elastic wave device in which a recess is provided on an upper side of a support, a piezoelectric thin film covers the recess, and an IDT electrode is provided on an upper surface of the piezoelectric thin film. A plate wave of an S0 mode or SH0 mode is used. A plurality of grooves are provided in the upper surface or lower surface of the piezoelectric thin film at a portion of the piezoelectric thin film that is positioned on a hollow section.

Embodiments of this disclosure relate to reducing coupling between acoustic wave resonators. An isolation region of a substrate can be located between acoustic wave resonators. The isolation region can reduce capacitive coupling through the substrate between the acoustic wave resonators. In certain embodiments, the isolation region can be located between acoustic wave resonators of different filters to thereby increase isolation between the filters.

Embodiments of this disclosure relate to methods of manufacturing acoustic wave components that include acoustic wave resonators that share a substrate. Laser light can be applied to alter a region of the substrate that is located between two of the acoustic wave resonators. Altering the region with laser light can reduce coupling between the two acoustic resonators through the substrate. The substrate can be monolithic after laser the light is applied.

An acoustic wave device includes: a piezoelectric substrate: a pair of comb-shaped electrodes located on the piezoelectric substrate, each of the comb-shaped electrodes including a plurality of electrode fingers; a support substrate having protruding portions and/or recessed portions in a region overlapping with the pair of comb-shaped electrodes in plan view, the protruding portions and/or recessed portions being regularly arranged; and an insulating layer directly or indirectly bonded between the piezoelectric substrate and the support substrate, a boundary face between the insulating layer and the support substrate being provided along the protruding portions and/or the recessed portions.

To provide a lithium niobate (LN) substrate which allows treatment conditions regarding a temperature, a time, and the like to be easily managed and in which an in-plane distribution of a volume resistance value is very small, and a method of producing the same. A method of producing an LN substrate by using an LN single crystal grown by the Czochralski process, in which an LN single crystal having a Fe concentration of 50 mass ppm or more and 1000 mass ppm or less in the single crystal and processed into a form of a substrate is buried in an Al powder or a mixed powder of Al and Al.sub.2O.sub.3, and heat-treated at a temperature of 450 C. or more and less than 500 C., to produce a lithium niobate single crystal substrate having a volume resistivity controlled to be within a range of 110.sup.8 .Math.cm or more to 110.sup.10 .Math.cm or less.

An acoustic wave filter device includes a substrate, a filter disposed on the substrate, a wall member disposed on the substrate and surrounding the filter, and a cap member disposed above the wall member and, with the wall member, forming an internal space. The cap member has a curved shape and comprises a first cap member comprising a first material and a second cap member comprising a second material.

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.

Due to strong needs to reduce the dimensions and the cost of the RF filters and to reduce the number of filters required in an mobile handsets and wireless system covering numbers of operation bands, tunable RF filters which can cover as many bands or frequency ranges as possible are needed so that the number of filters can be reduced in the mobile handsets and wireless systems. The present invention provides tunable surface acoustic wave (SAW) IDT structures with the resonant frequency of the acoustic wave to be excited and to be transmitted tuned by digital to analog converters (DACs). The DAC converts an input digital signal to an output DC voltage and provide DC bias voltages to the SAW IDTs through integrated thin film biasing resistors. The polarity and the value of the output DC voltage are controlled by the input digital signal to achieve selection and tuning of the resonant frequency of the SAW IDTs.

A composite substrate according to the present invention includes a support substrate having a diameter of 2 inches or more, and a piezoelectric substrate having a thickness of 20 m or less and bonded to the support substrate to transmit light. The piezoelectric substrate has a thickness distribution shaped like a fringe. A waveform having an amplitude within a range of 5 to 100 nm in a thickness direction and a pitch within a range of 0.5 to 20 mm in a width direction appears in the thickness distribution of the piezoelectric substrate in a cross section of the composite substrate taken along a line orthogonal to the fringe, and the pitch of the waveform correlates with a width of the fringe. In the piezoelectric substrate, the fringe may include either parallel fringes or spiral or concentric fringes.

Due to strong needs to reduce the dimensions and the cost of the RF filters and to reduce the number of filters required in an mobile handsets and wireless system covering numbers of operation bands, tunable RF filters which can cover as many bands or frequency ranges as possible are needed so that the number of filters can be reduced in the mobile handsets and wireless systems. The present invention provides tunable surface acoustic wave (SAW) IDT structures with the resonant frequency of the acoustic wave to be excited and to be transmitted tuned by digital to analog converters (DACs). The DAC converts an input digital signal to an output DC voltage and provide DC bias voltages to the SAW IDTs through integrated thin film biasing resistors. The polarity and the value of the output DC voltage are controlled by the input digital signal to achieve selection and tuning of the resonant frequency of the SAW IDTs.