Nonlinear acoustic media and related methods are described herein. The nonlinear acoustic media are configured to generate higher harmonic output signals from a single-frequency input signal. The higher harmonic output signals can be generated through the coupling of an acoustic dielectric medium to a nonlinear piezoelectric medium having four ports.

An acoustic resonator includes a wafer and a first phononic crystal disposed on the wafer to define an acoustic waveguide so as to propagate an acoustic wave along a propagation direction. The first phononic crystal includes a first two-dimensional (2D) array of metal stripes having a first period on the propagation direction. The apparatus also includes a second phononic crystal and a third phononic crystal disposed on two sides of the first phononic crystal and having a different period from the first period. The second phononic crystal and the wafer define a first reflector to reflect the acoustic wave. The third phononic crystal and the wafer define a second reflector to reflect the acoustic wave.

A piezoelectric device includes a piezoelectric single crystal body with a homogeneous polarization state and of which at least a portion flexurally vibrates, an upper electrode on an upper surface of the piezoelectric single crystal body, a lower electrode on a lower surface of the piezoelectric single crystal body, and a supporting substrate below the piezoelectric single crystal body. A recess extends from a lower surface of the supporting substrate toward the lower surface of the piezoelectric single crystal body.

Three-dimensional (3D) micro-scale shells are presented with openings of various sizes and geometries on the surface. The shell consist of a suspended ring-shaped resonator, multiple support beams, a support post, and a cap region that connects the support beams to the support post. Shells with openings of various sizes and geometries allow the creation of micro electromechanical systems (MEMS) sensors and actuators with a wide range of engineered mechanical and electrical properties. The openings on the shell surface can, for example, control the mechanical quality factor (Q) and resonance frequencies of the shell when the shell is used as a suspended proof mass of a mechanical resonator of a vibratory gyroscope. The shells can also serve as mechanical supporting layers and/or an electrode connection layer for MEMS actuators and sensors that use 3D shells as proof masses.

MEMS based sensors, particularly capacitive sensors, potentially can address critical considerations for users including accuracy, repeatability, long-term stability, ease of calibration, resistance to chemical and physical contaminants, size, packaging, and cost effectiveness. Accordingly, it would be beneficial to exploit MEMS processes that allow for manufacturability and integration of resonator elements into cavities within the MEMS sensor that are at low pressure allowing high quality factor resonators and absolute pressure sensors to be implemented. Embodiments of the invention provide capacitive sensors and MEMS elements that can be implemented directly above silicon CMOS electronics.

A piezoelectric device includes a piezoelectric body at least a portion of which can bend and vibrate, an upper electrode on an upper surface of the piezoelectric body and in which distortion of a crystal lattice is reduced as a distance from the upper surface of the piezoelectric body increases, a lower electrode on a lower surface of the piezoelectric body and in which distortion of a crystal lattice is reduced as a distance from the upper surface of the piezoelectric body increases, and a support substrate below the piezoelectric body, in which a recess extending from a lower surface of the support substrate toward the lower surface of the piezoelectric device is provided.

A mechanical resonator device. The resonator device includes a resonator element made of an elastic material under tensile stress and adapted for sustaining at least one oscillation mode; and a clamping structure supporting the resonator element. The clamping structure has a phononic density of states exhibiting a bandgap or quasi-bandgap such that elastic waves of at least one polarisation and/or frequency are not allowed to propagate through the clamping structure. The resonator element and the clamping structure are configured to match with a soft-clamping condition that elastic waves of polarisation and/or frequency corresponding to the at least one oscillation mode of the resonator penetrate evanescently into the clamping structure in a manner such as to minimize bending throughout the entire resonator device. Thereby, bending related loss may be minimized and the Q-factor of the mechanical resonator may be maximized.

A vibrator is provided that includes a substrate having a major surface defined in width and length directions and one or more electrodes formed at least in a substantial entire region of the major surface of the substrate in the length direction, and that performs, as main vibration, expansion-contraction vibration along the width direction in accordance with a voltage applied to the electrodes. Moreover, a holder surrounds at least a portion of the vibrator; and a holding arm connects the vibrator to the holder. Moreover, the vibrator has a width Wo in the width direction positioned at an end in the length direction and includes, to have a width Wm differing from the width Wo and positioned between a pair of ends opposing in the length direction, a variant portion at least one or more locations that is in a shape recessed or projecting in the width direction.

A Fin Bulk Acoustic Resonator (FinBAR) includes a fin integrally fabricated on a substrate of a glass or a semiconductor, an inner electrode deposited on the fin, a piezoelectric layer disposed on the inner electrode, an outer electrode deposited on the piezoelectric layer, a first electrode and a second electrode formed on the top surface of the substrate and connected to the inner and outer electrodes respectfully. The fin is characterized with a larger height than its width. A FinBAR array including a number of the FinBARs with different fin widths sequentially located on one chip is capable of continuously filtering frequencies in UHF and SHF bands.

A tunable non-reciprocal frequency limiter with an asymmetric micro-electro-mechanical resonator has two independent transducer ports. One port has a film stack including a 10 nm hafnium zirconium oxide (HZO) and another port has a film stack including a 120 nm aluminum nitride (AlN) film. These film stacks are deposited on top of 70 nm single crystal silicon substrate applying CMOS compatible fabrication techniques. The asymmetric transducer architecture with dissimilar electromechanical coupling coefficients force the resonator into mechanical nonlinearity on actuation with transducer having larger coupling. A proof-of-concept electrically-coupled channel filter is demonstrated with two such asymmetric resonators at ˜253 MHz with individual Q.sub.res of ˜870 and a non-reciprocal transmission ratio (NTR) ˜16 dB and BW.sub.3 dB of 0.25%.