An acoustic wave filter includes a substrate, a first resonator disposed on the substrate, a second resonator disposed on the substrate to be spaced apart from the first resonator, a connector electrically connecting the first and second resonators, and a variable capacitor formed in the connector to tune a pass band frequency of the acoustic wave filter.

A manufacturing method for an optical deflector, in which a piezoelectric film layer having a uniform film thickness is formed on a substrate layer, includes forming a cavity to open to a SiO.sub.2 layer side in a forming region of an outside piezoelectric actuator by etching an SOI wafer from the SiO.sub.2 layer side, covering an exposed surface of the cavity with a SiO.sub.2 layer, and joining the SiO.sub.2 layer of the SOI wafer and a support layer of an SOI wafer to manufacture an SOI wafer in which the cavity is enclosed. Next, after a recess is formed on a back side of the SOI wafer, anisotropic dry etching is carried out from the back side in a depth direction of the recess to remove the SiO.sub.2 layer.

An apparatus is disclosed for site-selective piezoelectric-layer trimming. The apparatus includes at least one surface-acoustic-wave filter with an electrode structure and a piezoelectric layer. The electrode structure has multiple gaps. The piezoelectric layer has a planar surface defined by a first (X) axis and a second (Y) axis that is perpendicular to the first (X) axis. The piezoelectric layer is configured to propagate an acoustic wave along the first (X) axis. The piezoelectric layer includes a first portion that supports the electrode structure and a second portion that is exposed by the multiple gaps of the electrode structure. The second portion has different heights across the second (Y) axis. The different heights are defined with respect to a third (Z) axis that is substantially normal to the planar surface.

A crystal vibrator that includes a crystal substrate having a front surface and a rear surface, including a vibration portion in a region including a center of the crystal substrate, and a first peripheral portion that surrounds a periphery of the vibration portion and that has a smaller thickness than the vibration portion. Drive electrodes are formed on both surfaces of the vibration portion of the crystal substrate. In at least one of the front surface and the rear surface of the crystal substrate, a step is provided between the vibration portion and the first peripheral portion, and a first peripheral edge portion of the vibration portion and a second peripheral edge portion of the first peripheral portion are in a curved surface shape.

A piezoelectric device includes a diaphragm, a piezoelectric actuator, and an orientation layer between the diaphragm and the piezoelectric layer. The piezoelectric actuator has a first electrode, a piezoelectric layer, and a second electrode, with the first electrode, a piezoelectric layer, and a second electrode on the diaphragm. The orientation layer is a stack of two or more tiers.

Described herein is a method of bonding a piezoelectric substrate to a support substrate to form a composite substrate. The piezoelectric substrate has one surface which is positively polarized, and a second surface which is negatively polarized. The method described herein includes the steps of bonding the positively polarized surface of the piezoelectric substrate to one surface of the support substrate by a direct bonding method.

A piezoelectric element includes a second electrode layer on a second surface of a single-crystal piezoelectric layer. A hole continuous with a through-hole is provided in the second electrode layer. The second electrode layer is made of Pt, Ti, Al, Cu, Au, Ag, Mg, or an alloy including at least one of the metals as a main ingredient. A third electrode layer is on one side of the second electrode layer opposite to the single-crystal piezoelectric layer. The third electrode layer includes at least a portion outside of an edge of the hole with a distance maintained relative to the edge of the hole when viewed in a direction perpendicular or substantially perpendicular to the second surface. The third electrode layer is made of Ni or an alloy including Ni as a main ingredient.

A support structure includes an internal cavity. An elastic membrane extends to divide the internal cavity into a first chamber and a second chamber. The elastic membrane includes a nanometric-sized pin hole extending there through to interconnect the first chamber to the second chamber. The elastic membrane is formed of a first electrode film and a second electrode film separated by a piezo insulating film. Electrical connection leads are provided to support application of a bias current to the first and second electrode films of the elastic membrane. In response to an applied bias current, the elastic membrane deforms by bending in a direction towards one of the first and second chambers so as to produce an increase in a diameter of the pin hole.

A crystal vibrator includes an AT-cut crystal substrate with a vibration portion having a principal surface and a peripheral portion surrounding and thinner than the vibration portion. An excitation electrode is formed on the principal surface and an extension electrode is electrically connected to the excitation electrode. The vibration portion has a first short-edge side lateral surface that abuts the peripheral portion at an acute angle and a tapered lateral surface adjacent to the first short-edge side lateral surface and inclined with respect to the X axis in the XZ′ plane. The tapered lateral surface abuts the peripheral portion at an angle that is greater than the angle defined by the first short-edge side lateral surface. The extension electrode extends from the excitation electrode through the tapered lateral surface to a first short-edge side in a longitudinal direction parallel to the Z′ axis.

A piezoelectric driving device includes: a piezoelectric vibrating body which includes a plurality of piezoelectric elements each formed of a first electrode, a second electrode, and a piezoelectric body positioned between the first electrode and the second electrode, and is disposed at least one surface of the first surface and the second surface of the vibrating plate, wherein the plurality of piezoelectric elements are connected in series.