Disclosed are a resonant device and an acoustic filter. The resonant device includes a wafer substrate, a piezoelectric layer and an interdigital electrode layer. The piezoelectric layer is located on a side of the wafer substrate and includes a piezoelectric monocrystal material, and the piezoelectric monocrystal material includes a first crystal axis, a second crystal axis and a third crystal axis perpendicular to each other. A direction of an electric field generated by the interdigital electrode layer in the piezoelectric layer is a device direction.

Certain aspects of the present disclosure provide an electroacoustic device and methods for signal processing via the electroacoustic device. One example electroacoustic device generally includes a first surface acoustic wave (SAW) resonator comprising a first apodized interdigital transducer (IDT) disposed between a first busbar and a second busbar, and a second SAW resonator comprising a second apodized IDT disposed between the second busbar and a third busbar, wherein the second busbar is at an angle with respect to at least one of the first busbar or the third busbar.

Aspects of this disclosure relate to a surface acoustic wave filter with an integrated temperature sensor. The integrated temperature sensor can be a resistive thermal device configured as a reflective grating for a surface acoustic wave resonator, for example. A radio frequency system can provide over temperature protection by reducing a power level of a radio frequency signal provided to the surface acoustic wave filter responsive to an indication of temperature provided by the integrated temperature sensor satisfying a threshold.

A superconducting device that mixes surface acoustic waves and techniques for fabricating the same are provided. A superconducting device can comprise a first surface acoustic wave resonator comprising a first low-loss piezo-electric dielectric substrate. The superconducting device can also comprise a second surface acoustic wave resonator comprising a second low-loss piezo-electric dielectric substrate. Further, the superconducting device can comprise a Josephson ring modulator coupled to the first surface acoustic wave resonator and the second surface acoustic wave resonator. The Josephson ring modulator is a dispersive nonlinear three-wave mixing element.

Aspects of this disclosure relate to a surface acoustic wave device with a vertical stack over a piezoelectric layer. The vertical stack can include a first acoustic reflector disposed on the piezoelectric layer, a second acoustic reflector disposed on the piezoelectric layer, and an interdigital transducer electrode disposed on the piezoelectric layer and positioned between the first acoustic reflector and the second acoustic reflector. The interdigital transducer electrode has a first side that is closer to the first acoustic reflector and a second side that is closer to the second acoustic reflector. A vertical arrangement of the vertical stack can be configured such that an acoustic wave propagation velocity of a first region between the first side and a first reflector is faster than an acoustic wave propagation velocity of a second region between the first side and the second side.

Aspects of this disclosure relate to a surface acoustic wave filter with an acoustic velocity adjustment structure. The surface acoustic wave filter can include a first interdigital transducer electrode disposed on a piezoelectric layer, an acoustic reflector disposed on the piezoelectric layer, and a second interdigital transducer electrode disposed on the piezoelectric layer. The second interdigital transducer electrode is longitudinally coupled to the first interdigital transducer electrode and positioned between the first interdigital transducer electrode and the acoustic reflector. The acoustic velocity adjustment structure can be positioned over at least a gap between the first interdigital transducer electrode and the second interdigital transducer electrode. The acoustic velocity adjustment structure can be arranged to increase an acoustic wave propagation velocity in a first region that includes the gap relative to a second region over at least a portion of the first interdigital transducer electrode.

Aspects of this disclosure relate to a surface acoustic wave device that includes a first reflector over a piezoelectric layer, a second reflector over the piezoelectric layer, and an interdigital transducer electrode structure over the piezoelectric layer and positioned between the first reflector and the second reflector. The surface acoustic wave device includes a velocity adjustment layer arranged to adjust acoustic velocity in a region of the surface acoustic wave device. The velocity adjustment layer can be a high speed layer or a low speed layer.

An acoustic wave device comprises a piezoelectric substrate, interdigital transducer electrodes having an electrode pitch λ.sub.0, and first and second reflector gratings disposed on opposite respective sides of the interdigital transducer electrodes in a propagation direction of a main acoustic wave through the acoustic wave device, the first reflector grating having a different electrode pitch λ.sub.1 than an electrode pitch λ.sub.2 of the second reflector grating to suppress ripples in a conductance curve of the acoustic wave device.

A filter includes: a piezoelectric substrate; a first acoustic wave resonator located on the piezoelectric substrate and including a pair of first reflectors including first grating electrodes and a pair of first comb-shaped electrodes that is located between the first reflectors and includes first electrode fingers; and a second acoustic wave resonator that is connected in series or parallel with the first acoustic wave resonator, is located on the piezoelectric substrate, and includes a pair of second reflectors including second grating electrodes and a pair of second comb-shaped electrodes that is located between the second reflectors and includes second electrode fingers, an average value of duty ratios of the second grating electrodes being different from an average value of duty ratios of the first grating electrodes, an average value of pitches of the second electrode fingers being substantially equal to an average value of pitches of the first electrode fingers.

A superconducting device that mixes surface acoustic waves and techniques for fabricating the same are provided. A superconducting device can comprise a first surface acoustic wave resonator comprising a first low-loss piezo-electric dielectric substrate. The superconducting device can also comprise a second surface acoustic wave resonator comprising a second low-loss piezo-electric dielectric substrate. Further, the superconducting device can comprise a Josephson ring modulator coupled to the first surface acoustic wave resonator and the second surface acoustic wave resonator. The Josephson ring modulator is a dispersive nonlinear three-wave mixing element.