Abstract: An acoustic driver assembly for use with any of a variety of cavitation chamber configurations, including spherical and cylindrical chambers as well as chambers that include at least one flat coupling surface, is provided. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass. The end surface of the head mass is shaped so that only a ring of contact is made between the outer perimeter of the head mass of the driver assembly and the cavitation chamber to which the driver is attached. The area of the contact ring is controlled by shaping its surface.

Abstract: An acoustic driver assembly for use with any of a variety of cavitation chamber configurations, including spherical and cylindrical chambers as well as chambers that include at least one flat coupling surface. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass. The end surface of the head mass is shaped to limit the contact area between the head mass of the driver assembly and the cavitation chamber to which the driver is attached, the contact area being limited to a centrally located contact region. The area of contact is controlled by limiting its size and/or shaping its surface.

Abstract: A method of fabricating a spherical cavitation chamber. Depending upon the chamber's composition and wall thickness, chambers fabricated with the disclosed techniques can be used with either low or high pressure systems. During chamber fabrication, initially two spherical half portions are fabricated and then the two half portions are joined together to form the desired cavitation chamber. During the fabrication of each chamber half, the interior spherical surface is completed first and then the outer spherical surface. Prior to joining the two spherical cavitation chamber halves, the surfaces to be mated are finished, preferably to a surface flatness of at least ±0.01 inches. Brazing is used to join the chamber halves together. The brazing material is preferably in the form of a ring-shaped sheet with outside and inside diameters of approximately the same size as the cavitation sphere's outside and inside diameters. Preferably the brazing operation is performed under vacuum conditions.

Abstract: A method of constructing a port assembly for use with a single piece cavitation chamber, typically a spherical chamber, is provided. The port assembly includes a cone-shaped port, a cone-shaped mounting ring and a central member mounted within the mounting ring. The mounting ring is located within the chamber prior to the final assembly of the chamber itself, i.e., at a time in which the chamber is comprised of multiple pieces. After the final assembly of the chamber is complete, a central member such as a window, plug, gas feed-thru, liquid feed-thru, mechanical feed-thru or sensor assembly is placed within the chamber. The mounting ring is then pulled into place within the cone-shaped port, followed by the central member. To expedite assembly, specialized tools can be used to pull the mounting ring and the central member into place.

Abstract: A method and apparatus for improving the beam quality of the emissions from a multimode gain medium such as a broad-stripe laser through the use of SBC techniques is provided. In order to achieve the desired beam quality without a significant reduction in output power, discrete lasing regions are formed across the gain medium using an etalon or similar device located within the SBC cavity.

Abstract: A crucible is provided that is thermally stable at high temperatures and is suitable for use in the growth of large, bulk AlN, AlxGa1-xN or other nitride single crystals. The crucible is comprised of specially treated tantalum. During the initial treatment, the walls of the crucible are carburized, thus achieving a crucible that can be subjected to high temperatures without deformation. Once the carburization of the tantalum is complete, the crucible undergoes further treatment to protect the surfaces that are expected to come into contact with nitride vapors during crystal growth with a layer of TaN. If the crucible is to be used with a graphite furnace, only the inner surfaces of the crucible are converted to TaN, thus keeping TaC surfaces adjacent to the graphite furnace elements. If the crucible is to be used with a non-graphite furnace, both the inner and outer surfaces of the crucible are converted to TaN.

Abstract: An acoustic driver assembly for use with a spherical cavitation chamber is provided. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass, coupled together with a centrally located threaded means (e.g., all thread, bolt, etc.). The driver assembly is either attached to the exterior surface of the spherical cavitation chamber with the same threaded means, a different threaded means, or a more permanent coupling means such as brazing, diffusion bonding or epoxy. In at least one embodiment, the transducer is comprised of a pair of piezo-electric transducers, preferably with the adjacent surfaces of the piezo-electric transducers having the same polarity. The surface of the head mass that is adjacent to the external surface of the chamber has a spherical curvature greater than the spherical curvature of the external surface of the chamber, thus providing a ring of contact between the acoustic driver and the cavitation chamber.

Abstract: An acoustic driver assembly for use with a spherical cavitation chamber is provided. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass, coupled together with a centrally located threaded means (e.g., all thread, bolt, etc.). The head mass of the driver assembly is permanently attached to the exterior surface of the spherical cavitation chamber via brazing or diffusion bonding. In at least one embodiment, the transducer is comprised of a pair of piezo-electric transducers, preferably with the adjacent surfaces of the piezo-electric transducers having the same polarity. The surface of the head mass that is adjacent to the external surface of the chamber has a spherical curvature equivalent to the spherical curvature of the external surface of the chamber, thus providing maximum coupling efficiency between the acoustic driver and the cavitation chamber.

Abstract: A radioactive power source resident in an IC package is provided. The power source is a stand-alone device, fabricated separately from the IC or other device that is eventually attached to the package. The power source may be attached to the packaging substrate or to another portion of the package such as the package's top member or lid. The source can be directly coupled to the mounted IC, for example via package leads, or coupled to package pins. By coupling the source to the package pins, the system provides even greater flexibility. Although the power source can use any of a variety of different cell designs, preferably an icosahdedral boride based beta cell is used.

Abstract: An acoustic driver assembly for use with a spherical cavitation chamber is provided. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass, coupled together with a centrally located threaded means (e.g., all thread, bolt, etc.). The driver assembly is either attached to the exterior surface of the spherical cavitation chamber with the same threaded means, a different threaded means, or a more permanent coupling means such as brazing, diffusion bonding or epoxy. In at least one embodiment, the transducer is comprised of a pair of piezo-electric transducers, preferably with the adjacent surfaces of the piezo-electric transducers having the same polarity. The surface of the head mass that is adjacent to the external surface of the chamber has a spherical curvature less than the spherical curvature of the external surface of the chamber, thus providing a ring of contact between the acoustic driver and the cavitation chamber.

Abstract: An acoustic driver assembly for use with a spherical cavitation chamber is provided. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass, coupled together with a centrally located threaded means (e.g., all thread, bolt, etc.). The driver assembly is permanently attached to the exterior surface of the spherical cavitation chamber via brazing or diffusion bonding. In at least one embodiment, the transducer is comprised of a pair of piezo-electric transducers, preferably with the adjacent surfaces of the piezo-electric transducers having the same polarity. The surface of the head mass that is adjacent to the external surface of the chamber has a spherical curvature equivalent to the spherical curvature of the external surface of the chamber, thus providing maximum coupling efficiency between the acoustic driver and the cavitation chamber. In at least one embodiment a void filling material is interposed between one or more pairs of adjacent surfaces of the driver assembly.

Abstract: An acoustic driver assembly for use with a spherical cavitation chamber is provided. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass, coupled together with a centrally located threaded means (e.g., all thread, bolt, etc.). The driver assembly is either attached to the exterior surface of the spherical cavitation chamber with the same threaded means, a different threaded means, or a more permanent coupling means such as brazing, diffusion bonding or epoxy. In at least one embodiment, the transducer is comprised of a pair of piezo-electric transducers, preferably with the adjacent surfaces of the piezo-electric transducers having the same polarity. The surface of the head mass that is in contact with the external surface of the chamber has a spherical curvature equivalent to the spherical curvature of the external surface of the chamber, thus providing maximum surface contact between the driver assembly and the chamber.

Abstract: An acoustic driver assembly for use with a spherical cavitation chamber is provided. The acoustic driver assembly includes at least one transducer, a head mass and a tail mass, coupled together with a centrally located threaded means (e.g., all thread, bolt, etc.). The driver assembly is either attached to the exterior surface of the spherical cavitation chamber with the same threaded means, a different threaded means, or a more permanent coupling means such as brazing, diffusion bonding or epoxy. In at least one embodiment, the transducer is comprised of a pair of piezo-electric transducers, preferably with the adjacent surfaces of the piezo-electric transducers having the same polarity. The surface of the head mass that is adjacent to the external surface of the chamber has a spherical curvature greater than the spherical curvature of the external surface of the chamber, thus providing a ring of contact between the acoustic driver and the cavitation chamber.

Abstract: A method for fabricating a p-n heterojunction device is provided, the device being preferably comprised of an n-type GaN layer co-doped with silicon and zinc and a p-type AlGaN layer. The device may also include a p-type GaN capping layer. The device can be grown on any of a variety of different base substrates, the base substrate comprised of either a single substrate or a single substrate and an intermediary layer. The device can be grown directly onto the surface of the substrate without the inclusion of a low temperature buffer layer.

Abstract: A method and apparatus for achieving multicolor displays using an integrated color chip is provided. The integrated color chip contains one or more multicolor generation sites on a single substrate. Each multicolor generation site is comprised of two or more light emitting regions in close proximity to one another, the number of light emitting regions per site dependent upon the number of required colors. The active light generation system for each light emitting region, e.g., an LED, is preferably identical in device structure although size and shape may vary. In order to achieve the desired colors, one or more light conversion layers are applied to individual light emitting regions. Each light emitting region may also include index matching layers, preferably interposed between the outermost surface of the light emitter and the light conversion layer, and protective layers.

Abstract: A low defect (e.g., dislocation and micropipe) density silicon carbide (SiC) is provided as well as an apparatus and method for growing the same. The SiC crystal, grown using sublimation techniques, is preferably divided into two stages of growth. During the first stage of growth, the crystal grows in a normal direction while simultaneously expanding laterally. Although dislocations and other material defects may propagate within the axially grown material, defect propagation and generation in the laterally grown material are substantially reduced, if not altogether eliminated. After the crystal has expanded to the desired diameter, the second stage of growth begins in which lateral growth is suppressed and normal growth is enhanced. A substantially reduced defect density is maintained within the axially grown material that is based on the laterally grown first stage material.

Abstract: A method for fabricating p-type, i-type, and n-type III-V compound materials using HVPE techniques is provided. If desired, these materials can be grown directly onto the surface of a substrate without the inclusion of a low temperature buffer layer. By growing multiple layers of differing conductivity, a variety of different device structures can be fabricated including simple p-n homojunction and heterojunction structures as well as more complex structures in which the p-n junction, either homojunction or heterojunction, is interposed between a pair of wide band gap material layers. The provided method can also be used to fabricate a device in which a non-continuous quantum dot layer is grown within the p-n junction. The quantum dot layer is comprised of a plurality of quantum dot regions, each of which is typically between approximately 20 and 30 Angstroms per axis. The quantum dot layer is preferably comprised of AlxByInzGa1-x-y-zN, InGaN1-a-bPaAsb, or AlxByInzGa1-x-y-zN1-a-bPaAsb.

Abstract: A method for fabricating thin films of an icosahedral boride on a silicon carbide (SiC) substrate is provided. Preferably the icosahedral boride layer is comprised of either boron phosphide (B12P2) or boron arsenide (B12As2). The provided method achieves improved film crystallinity and lowered impurity concentrations. In one aspect, an epitaxially grown layer of B12P2 with a base layer or substrate of SiC is provided. In another aspect, an epitaxially grown layer of B12As2 with a base layer or substrate of SiC is provided. In yet another aspect, thin films of B12P2 or B12As2 are formed on SiC using CVD or other vapor deposition means. If CVD techniques are employed, preferably the deposition temperature is above 1050° C., more preferably in the range of 1100° C. to 1400° C., and still more preferably approximately 1150° C.

Abstract: A wide variety of Fiber Bragg writing devices comprising solid state lasers are provided. The solid state lasers emit moderate peak-power output beams which are suitable for efficient production of fiber Bragg gratings without causing embrittlement of the optical waveguide. These solid state lasers generate output beams with wavelengths of approximately 240 nm, in order to match the primary absorption peak in the ultraviolet range for a typical optical waveguide. In some embodiments, the solid state lasers comprise Ti:sapphire lasers which are tuned to produce fundamental wavelengths which are frequency-multiplied. In other embodiments, the output beam of a Ti:sapphire laser is mixed with a harmonic beam from a pump laser. Some embodiments output the third harmonic of a fundamental beam.

Abstract: A wide variety of Fiber Bragg writing devices comprising solid state lasers are provided. The solid state lasers emit moderate peak-power output beams which are suitable for efficient production of fiber Bragg gratings without causing embrittlement of the optical waveguide. These solid state lasers generate fourth harmonic output beams with wavelengths of approximately 240 nm, in order to match the primary absorption peak in the ultraviolet range for a typical optical waveguide. Some of these solid state lasers comprise a fequency-doubling crystal and a CLBO crystal used in a non-critically phase-matched orientation as a frequency-quadrupling crystal. In such lasers, both the frequency-doubling crystal and frequency-quadrupling crystal are preferably engineered to minimize or eliminate beam “walkoff.