An acoustic resonator structure includes an acoustic stack. The acoustic stack comprises: a substrate having a first surface and a second surface; a piezoelectric layer disposed over the substrate, the piezoelectric layer having a first surface, and a second surface. The first surface of the substrate, or the second surface of the piezoelectric layer, comprises a plurality of features; and a plurality of electrodes disposed over the first surface of the piezoelectric layer. The plurality of electrodes is configured to generate acoustic waves in the piezoelectric layer. The acoustic stack also includes a temperature compensation layer disposed between the first surface of the substrate and the second surface of the piezoelectric layer.

A surface acoustic wave resonator that has at least a first resonant frequency and a second resonant frequency is disclosed. The surface acoustic wave resonator can include an interdigital transducer electrode that is positioned over a piezoelectric layer. The interdigital transducer electrode includes fingers having a first pitch. The surface acoustic wave resonator can also include a first set of reflectors that is positioned over the piezoelectric layer. The first set of reflectors includes a first number of reflectors having a second pitch. The first pitch is greater than the second pitch. The surface acoustic wave resonator can also include a second set of reflectors that is positioned over the piezoelectric layer. The second set of reflectors includes a second number of reflectors having a third pitch. The second number of reflectors is different from the first number of reflectors.

An acoustic wave device includes a substrate, a first resonator, a second resonator, and a shared reflector. The second resonator is adjacent to the first resonator and has different frequency characteristics different than the first resonator. The first resonator includes a first interdigital transducer electrode. The second resonator includes a second interdigital transducer electrode. The shared reflector has frequency characteristics that are the same as both frequency characteristics of the first resonator and frequency characteristics of the second resonator or between the frequency characteristics of the first resonator and the frequency characteristics of the second resonator. a higher-order mode frequency of the first resonator and a higher-order mode frequency of the second resonator coincides. When the number of electrode fingers of the shared reflector is even, an electrode finger facing the shared reflector in the first interdigital transducer electrode and an electrode finger facing the shared reflector in the second interdigital transducer electrode have the same polarity. When the number of electrode fingers of the shared reflector is odd, an electrode finger facing the shared reflector in the first interdigital transducer electrode and an electrode finger facing the shared reflector in the second interdigital transducer electrode have opposite polarities.

An acoustic wave device is disclosed. The acoustic wave device includes a piezoelectric layer, an interdigital transducer electrode positioned over the piezoelectric layer, and an anti-refection layer over a conductive layer of the interdigital transducer electrode. The conductive layer can include aluminum, for example. The anti-reflection layer can include silicon. The anti-reflection layer can be free from a material of the interdigital transducer electrode. The acoustic wave device can further include a temperature compensation layer positioned over the anti-reflection layer in certain embodiments.

A surface acoustic wave device comprising a base substrate, a piezoelectric layer and an electrode layer in between the piezoelectric layer and the base substrate, a comb electrode formed on the piezoelectric layer comprising a plurality of electrode means with a pitch p, defined asp=A, with A being the wavelength of the standing acoustic wave generated by applying opposite potentials to the electrode layer and comb electrode, wherein the piezoelectric layer comprises at least one region located in between the electrode means, in which at least one physical parameter is different compared to the region underneath the electrode means or fingers. A method of fabrication for such surface acoustic wave device is also disclosed. The physical parameter may be thickness, elasticity, doping concentration of Ti or number of protons obtained by proton exchange.

A surface acoustic wave resonator that has at least a first resonant frequency and a second resonant frequency is disclosed. The surface acoustic wave resonator can include an interdigital transducer electrode over a piezoelectric layer. The interdigital transducer electrode includes fingers having a first pitch. The surface acoustic wave resonator can also include a set of reflectors that is positioned over the piezoelectric layer. The set of reflectors includes a number of reflectors having a second pitch. The first pitch is greater than the second pitch. The number of reflectors is configured so as to compensate for degradation of a quality factor of the surface acoustic wave resonator due to having the first pitch greater than the second pitch.

A multimode longitudinally coupled surface acoustic wave resonator is disclosed. The multimode longitudinally coupled surface acoustic wave resonator can include a first interdigital transducer electrode that is positioned over a piezoelectric layer. The first interdigital transducer electrode includes fingers having a first pitch. The multimode longitudinally coupled surface acoustic wave resonator can also include first and second sets of reflectors that are positioned over the piezoelectric layer. The first and second sets of reflectors include a first number of reflectors having a second pitch and a second number of reflectors having a third pitch, respectively. The first pitch is greater than the second pitch. The multimode longitudinally coupled surface acoustic wave resonator can further include a second interdigital transducer electrode that is positioned over the piezoelectric layer and between the first interdigital transducer electrode and the first set of reflectors. The second interdigital transducer electrode includes fingers having a fourth pitch.

An acoustic wave device includes a piezoelectric substrate, an IDT electrode on the piezoelectric substrate and including first and second busbars including first and second interdigitated electrode fingers, and reflectors on the piezoelectric substrate facing each other across the IDT electrode. In the IDT electrode, a pair of regions outward of first and second base ends of the first and second electrode fingers are a pair of outer regions, and regions extending from the pair of outer regions are a pair of extended outer regions. Each of the reflectors includes a pair of reflector busbars facing each other and reflector electrode fingers electrically connected to the pair of reflector busbars. Each of the reflector busbars includes a plurality of reflector connection electrodes in a portion of the reflector located in one of the extended outer regions and directly or indirectly connected to the reflector electrode fingers.

An acoustic wave sensor device, comprising an interdigitated transducer; a first reflection structure arranged on one side of the interdigitated transducer, and a second reflection structure arranged on another side of the interdigitated transducer; a first resonance cavity comprising a first upper surface and formed between the interdigitated transducer and the first reflection structure; a second resonance cavity comprising a second upper surface and formed between the interdigitated transducer and the second reflection structure; and wherein the second upper surface comprises a physical and/or chemical modification as compared to the first upper surface.

A filter device includes first and second acoustic wave resonators each including a support, a piezoelectric layer that has an X-axis, a Y-axis, and a Z-axis that are crystal axes and is made of Y-cut lithium niobate, and an IDT electrode including first and second electrode fingers. When a thickness of the piezoelectric layer is d and a center-to-center distance of the first and second electrode fingers and the second electrode fingers adjacent to each other is p, d/p is less than or equal to 0.5. An absolute value of a first slant angle 1 differs from an absolute value of a second slant angle 2.