US Government As Represented by the Secretary of the Army

USA As Represented by Secretary of the Navy

Clemson University

Arthur D Ballato

John R Vig

John A Kosinski

Yicheng Lu

Mitra Dutta

Elio A Mariani

Gerald J Iafrate

Richard H Wittstruck

Jagadeesh Pamulapati

Hongen Shen

Xiaojun Tong

Theodore J Lukaszek

Mitsuo Nakazawa

Herbert A Leupold

Thomas W Grudkowski

John Ballato

Paul H Shen

Dana J Sturzebecher

David Claude Morton

Yook-Kong Yong

Michael A Stroscio

Hong-Liang Cui

Paul W Cooke

Owen P Layden

Edward R Baidy

Though the initial concept of the face-mounted resonator was ahead of fabrication technology, the solidly-mounted resonator (SMR) is now a practical resonator design yielding high Qs in a space-efficient and robust mounting configuration. An agile tunable piezoelectric SMR is now provided with a resonator and alternating stacks of high mechanical impedance and low mechanical impedance, piezoelectric layers advantageously stacked on a substrate with the piezoelectric layers connected to an adaptive circuit that alternates with an external electrical impedance having values anywhere between an open circuit and a short circuit. The piezoelectric Bragg stacks with alternating layers of high and low mechanical impedance and properties made variable via the additional piezoelectric properties of the stack materials overcomes difficulties caused by the limitations of manufacturing techniques, acoustic power leakage and inability to meet the single-frequency, quarter-wavelength criterion due to manufacturing deviations.

Agile tunable piezoelectric solidly-mounted resonator

A rigid, planar, non-resonating boundary is introduced parallel to the surface of the piezoelectric resonator in a measurand chamber in order to both reduce the separation space (l) between the resonator and confining wall and confine the measurand fluid between those surfaces in order to reliably measure acoustic viscosity independently form the mass density (&#x3c1;) of the measurand fluid. The hypothesis is that when the penetration depth (&#x3b4;) is comparable to the separation distance (l) between the resonator and the confining wall, then resonator perturbation is a sensitive function of the abbreviated separation space. Variations in the spacing between the resonator and confining wall are accomplished by adjusting the rigid, planar, non-resonating boundary, or confining wall, with a means for lateral movement. The ability to accurately adjust and control small spaces thereby enables MEMS versions of viscometers and associated types of fluid sensors.

Acoustic microelectromechanical viscometer

Recent theoretical investigations have predicted the existence of axially frozen modes that arise when light is incident upon an anisotropic two-dimensional photonic crystal. Such electromagnetic modes are of interest since they suggest a near-zero group velocity with extraordinary amplitudes. The present invention addresses the crystal physics associated with realizing such effects and provides for the development of materials suitable for use in the forming photonic crystals that can exhibit such effects.

Materials for freezing light

Thin film bulk acoustic wave sensors with coatings of biological and chemical materials, multiple electrode depositions and a piezo-active thin film transducer layer are hosted on a substrate. The thin film bulk acoustic wave sensor suite, or T-BASS, produces a low-voltage, IC-compliant thickness-directed electric field that is substantially uniform over a substantial portion of the active area of the BAW structure. The BAWs produced are essentially extensional plane waves propagating away from the substrate surface and having phase progression substantially oblique to the substrate surface. For BAW applications requiring sensing by an active layer, it would be most desirable to have an electrode structure that is both IC-compliant and can be energized from a low-voltage source of electrical energy. The thin film BAW sensors are compatible with IC fabrication and processing techniques, such as photolithography. Both single channel and multiple channel thin film bulk acoustic wave sensors are provided.

Thin film bulk acoustic wave sensor suite

An Interdigital Bulk Acoustic-Wave Transducer (IBAT) device is provided with pairs of exciting electrode fingers disposed sufficiently close together on the piezoelectric substrate and dielectric coating over the exciting electrode fingers to generate an IC-compatible voltage at relatively high electric field strength, resulting in a reduced region of excitation and uniform electric field strength distribution. The IBAT advantageously produces a lateral electric field substantially uniform over a substantial portion of the active BAW structure area, reducing, or virtually eliminating sharp voltage spikes, an electrical field produced by the low voltages resident on integrated circuit (IC) chips, usually of a magnitude of 10 volts, or lower, the planar electrode structure being compatible with IC processing techniques, such as photolithography and the BAWs produced thereby being essentially plane waves, with propagation away from, but with phase progression substantially parallel to, the substrate surface. Numerous IBAT structural arrangements are possible by advantageously over-coating the IBAT electrode finger stripes with an insulating dielectric in different configurations, and any possible configuration achieved through over-coating is considered to be within the contemplation of the devices and methods of the present invention. Interdigital bulk acoustic wave transducers and methods for exciting bulk acoustic waves with interdigital electrode fingers are also provided.

Lateral field excitation of bulk acoustic waves from an IC-compliant low voltage source

Double-sided, single-sided and ring electrode mesa resonators are provided that operate in the difficult 3 GHZ frequency with an electrode-free resonator area that serves as an energy-trapping area. The double-sided electrode-free resonator device is a double-sided mesa resonator plate, top and bottom wells, a mesa, and top and bottom electrodes deposited in such a way that the electrodes cover the plate surface and surround the mesa, which allows the mesa to protrude above the electrodes and provide an electrode-free resonator area. The top and bottom electrodes, which are acoustically coupled and controlled by acoustic gaps, create an electro-magnetic field and an excitation voltage within a vibrating area of the resonator plate generates an acoustic energy which is trapped within the resonator area and confined to the resonator area to minimize a leakage of the acoustic energy and provide a high Q factor at 3 GHz. The resonator has a resonator frequency determined by a resonator thickness dimension, t, influences the resonator area's ability to function as an active element trapping the acoustic energy. The inventors herein have observed a strong relationship between decreased resonator thickness and motional impedance. Double-sided and single-sided filter devices based on the same principles are also provided.

Electrode-free resonator structures for frequency control, filters and sensors

Methods are included for determining deviations from &phgr;&equals;0&deg; in test resonators based on the quasi-pure modes' displacement ratio variations with &phgr; angle. A direct relationship between deviation from &phgr;&equals;0&deg; and the c-mode displacement ratio has been observed, so that the larger the deviation from &phgr;&equals;0&deg;, then the larger is the change in the normalized frequency of the c-mode upon immersion in, or contact with, a fluid. The method includes measuring &thgr; and &phgr; angles in reference resonators with different small &phgr; angles and quasi-pure mode frequencies of reference resonators in both air and a test fluid at ambient temperatures, calculating the normalized frequency changes between the air and fluid measurements as a reference point, measuring the test resonator in air then in the fluid and comparing the results. Also includes are similar methods for measuring the &phgr; angles in the quasi-pure mode of near-BT-cut resonator plates and the LGX family of rotated-y-cut ZTC crystal resonators, so that the appropriate modes' displacement ratio variations with the &phgr; angle determine deviations from &phgr;&equals;0&deg;. In the preferred method of this invention the test fluid used for measuring a reference fluid quasi-pure mode frequency is pure water at ambient temperature.

Method of determining angle-of-cut

The present invention is a piezoelectric device fabricated on a semiconductor that also contains electronic circuitry. A cooling device is used to lower the temperature of the resonator. Electronic circuitry can provide feedback to the resonator to compensate for microphonics that occur at low temperatures. Alternatively, piezoelectric materials that can operate at high temperatures can create a high temperature frequency source.

Compound semiconductor monolithic frequency sources and actuators

Techniques for determining the properties of a liquid include placing one or more acoustic crystal resonators in contact with the fluid. An oscillator circuit drives each of the resonators at one or more different modes. A frequency counter connected to the oscillator monitors the operating frequencies of the resonators before and after the surfaces are placed in contact with the liquid. A computer, which is responsive to the outputs of the frequency counter, includes a liquid property system for determining difference frequencies by comparing the operating frequencies measured by the frequency counter with predetermined reference frequencies. The computer calculates the properties of the liquid from the difference frequencies.

Techniques for sensing the properties of fluids with a resonator assembly

A technique of determining the properties of a liquid. One or more resonators are exposed to air or another reference fluid of known properties. Oscillator circuits drive the resonators at at least two different frequencies. Frequency counters measure the fluid-operating frequencies of the resonators while they are in contact with the reference fluid. The resonators are then immersed in liquid as the oscillator circuits drive the resonators. The liquid-operating frequencies are measured by the frequency counters while the resonators are in contact with the liquid. A computer compares the fluid-operating frequencies and the liquid-operating frequencies to obtain difference frequencies that are independent functions of the liquid's properties. A computer determines the liquid properties from the difference frequencies.

Techniques for sensing the properties of fluids with resonators

An MQW is fabricated such that at a particular level of purely mechanical ress/strain the optical properties of the MQW are altered by breaking the heavy and light hole degeneracy (splitting of the heavy and light holes in the valence band) of the MQW in the E-k domain. In a preferred embodiment of the invention ring electrical contacts are disposed on the MQW and the entire MQW structure, including electrical contacts is mounted on a piezoelectric substrate, with the proper crystallographic orientation and strain induced orientation, via an epoxy. In operation, a bias is applied to the MQW structure and the piezoelectric substrate. The bias causes quantum decoupling of the heavy and light holes; however, the bias also will cause the piezoelectric material to move, which will induce a strain on the MQW structure. This strain will, in turn, also induce a decoupling of the heavy and light holes, but to a greater degree than the decoupling induced by the electrical bias and therefore, the absorption of the MQW will altered, thereby polarizing optical signal incident to (or through) the device.

Dynamic modulation of quantum devices

The invention is directed to resonators and more particularly to an MMIC-compatible resonator which can be fabricated on an MMIC chip using MMIC processing techniques. The MMIC-compatible resonator has a substrate approximately 100 microns thick made of semi-insulating GaAs and/or AlGaAs. The substrate flanks an air via on which is fabricated a thin film piezoelectric semi-insulating GaAs film, comprising the piezoelectrically active element. The piezoelectrically active element is flanked either laterally or from the top to bottom thereof by a pair of electrodes which serve to excite the thickness shear or thickness extensional mode of the thin film piezoelectrically active element. There are a number of III-V and II-VI binary compounds and ternary, and other piezoelectric semiconductor alloys, which can be used for the purposes of the invention. The thin film measures approximately 5 microns or less in thickness and is fabricated on the semi-insulating GaAs, on the �110!, �111! or �100! axis thereof.

Thickness mode acoustic wave resonator

In the faceplate of a cathode ray tube or in an FED the amount of light emanating from the phosphor that reaches a viewer is increased by the use of internal and external antireflection layers and concavities between layers on the side of the viewer with respect to the phosphor layer.

Method for detrapping light in thin film phosphor displays

A microcircuit package with an integrated acoustic isolator made up of a stacked acoustic filter. The package includes a rigid, electrically conductive housing with a IC module mounted therein. The acoustic filter includes two electroacoustic transducers mounted on opposite sides of a common wall of the package, one inside the package and the other outside. An a.c. power source is connected to the transducer that is mounted on the outside of the package. Electrical energy from the power source is converted by the outside transducer into acoustic energy which is conducted through the package wall to the inside transducer which reconverts the acoustic energy into electrical energy. The package wall has a significant thickness in comparison to the acoustic wavelength of the filter passband and is preferably equal to an integer number of one-half acoustic wavelengths. The transducer-wall combination acts as a filter having a passband tailored to prevent high-power microwave energy from being transmitted through the package wall.

Growing community of inventors

Long Branch, NJ, United States of America

Arthur D Ballato