Patents Represented by Attorney, Agent or Law Firm Glen E. Books
  • Patent number: 5550940
    Abstract: In accordance with the invention, an optical filter comprises a plurality of optical fibers having a coupling region where the axially extending cores are closely spaced within a common cladding. The coupling region includes a long period grating for selectively shifting light of selected wavelengths from guided modes into non-guided modes. These non-guided modes are picked up by an adjacent core and light of the selected wavelengths is thus shifted from one core to another. The result is an optical filter particularly useful as a demultiplexer or a tapping device. In one embodiment the grating is formed in one of the cores. In an alternative embodiment, it is formed in the common cladding.
    Type: Grant
    Filed: February 24, 1995
    Date of Patent: August 27, 1996
    Assignee: Lucent Technologies Inc.
    Inventors: Ashish M. Vengsarkar, Kenneth L. Walker
  • Patent number: 5538767
    Abstract: Applicants have discovered that films of conductively doped GaInO.sub.3 grown on substrates by pulsed laser deposition have conductivity comparable to conventional wide band-gap transparent conductors while exhibiting superior light transmission, particularly in the green and blue wavelength regions of the visible spectrum. Substrate temperatures ranged from room temperature to 350.degree. C. in an ambient containing oxygen at partial pressure in the range 0.1 mTorr to 100 mTorr. The preferred laser source was an excimer laser operating in the deep ultraviolet.
    Type: Grant
    Filed: January 24, 1995
    Date of Patent: July 23, 1996
    Assignee: AT&T Corp.
    Inventors: Robert J. Cava, Julia M. Phillips, Gordon A. Thomas
  • Patent number: 5534465
    Abstract: In accordance with the invention, a multichip circuit is fabricated by providing an active semiconductor substrate comprising a set of isolated components including active components such as transistors, forming on a surface of the substrate a plurality of paths incorporating components from the substrate for interconnecting a plurality integrated circuit devices, and mounting the ICs on the surface in contact with their respectively appropriate paths. The preferred active substrate is similar in structure to a silicon integrated circuit except that the circuit components are interconnected only by the paths interconnecting the ICs. Advantageously the ICs are surface mounted on the substrate.
    Type: Grant
    Filed: January 10, 1995
    Date of Patent: July 9, 1996
    Assignee: AT&T Corp.
    Inventors: Robert C. Frye, King L. Tai
  • Patent number: 5523587
    Abstract: In accordance with the invention, a thin layer of epitaxial silicon is grown at low temperatures at or below 300.degree. C. by the steps of providing a substrate, forming an oriented dielectric buffer layer on the substrate and growing epitaxial silicon on the buffer layer. Preferably the substrate has a glass surface and the oriented buffer layer is cubic ZrO.sub.2. The buffer layer is preferably oriented by bombarding it with a directed ion beam while the buffer layer is being deposited on the substrate. For example, a buffer layer of (100) cubic ZrO.sub.2 can be grown at a temperature as low as 300.degree. C. The oriented cubic ZrO.sub.2 is an excellent buffer for epitaxial silicon on glass due to a good match of lattice parameters with silicon and a good match of thermal expansion coefficients with glass. An oriented (100) silicon epitaxial film can then be grown on the epitaxial template provided by the buffer layer at a temperature as low as 250.degree. C.
    Type: Grant
    Filed: June 24, 1993
    Date of Patent: June 4, 1996
    Assignee: AT&T Corp.
    Inventor: Jueinai R. Kwo
  • Patent number: 5512818
    Abstract: In accordance with the present invention, a voltage proportional replication device comprises an input electromagnet responsive to an input voltage for producing a magnetic field in proportion to the input voltage; and a first magnetoresistive sensing element disposed within the field of the input electromagnet. The device further includes an adjustable source of output voltage; an output electromagnet responsive to the output voltage for producing a magnetic field in proportion to the output voltage; and a second magnetoresistive sensing element disposed within the field of the output electromagnet. A control circuit for controlling the adjustable output voltage maintains a constant ratio between the resistances of the first and second magnetoresistive elements, thereby maintaining a constant ratio between the input voltage and the output voltage.
    Type: Grant
    Filed: March 31, 1994
    Date of Patent: April 30, 1996
    Assignee: AT&T Corp.
    Inventors: Sungho Jin, Ashraf W. Lotfi, Mark T. McCormack
  • Patent number: 5504385
    Abstract: In accordance with the invention, a field emission device is made by disposing emitter material on an insulating substrate, applying a sacrificial film to the emitter material and forming over the sacrificial layer a conductive gate layer having a random distribution of apertures therein. In the preferred process, the gate is formed by applying masking particles to the sacrificial film, applying a conductive film over the masking particles and the sacrificial film and then removing the masking particles to reveal a random distribution of apertures. The sacrificial film is then removed. The apertures then extend to the emitter material. In a preferred embodiment, the sacrificial film contains dielectric spacer particles which remain after the film is removed to separate the emitter from the gate. The result is a novel and economical field emission device having numerous randomly distributed emission apertures which can be used to make low cost flat panel displays.
    Type: Grant
    Filed: August 31, 1994
    Date of Patent: April 2, 1996
    Assignee: AT&T Corp.
    Inventors: Sungho Jin, Gregory P. Kochanski, John Thomson, Jr.
  • Patent number: 5500031
    Abstract: In accordance with the invention, the index of refraction of a glassy material is increased by treating the material with hydrogen and applying heat. Specifically, the glass is exposed to hydrogen or deuterium at pressure in the range 14-11,000 p.s.i. and a temperature in the range 21.degree.-150.degree. C. for a time sufficient for the hydrogen to diffuse into the glass. The glass is then subjected to heat in excess of about 500.degree. C., as by application of a flame or infrared radiation. The duration of heating can be less than a second. The result is a substantial and long-lived increase in the normalized refractive index. For example, flame heating of H.sub.2 loaded commercial GeO.sub.2 doped optical fibers (AT&T Accutether single mode fiber) has produced normalized index changes .increment.n/n of 4.times.10.sup.-3. This process can be used to make and adjust a variety of optical waveguide devices.
    Type: Grant
    Filed: December 14, 1994
    Date of Patent: March 19, 1996
    Assignee: AT&T Corp.
    Inventors: Robert M. Atkins, Paul J. Lemaire, Victor Mizrahi, Kenneth L. Walker
  • Patent number: 5500916
    Abstract: A waveguide Bragg reflector is made by forming periodic grooves in either the undercladding or the core, applying a high index coating on the grooved surface and selectively removing the coating from the horizontal surfaces while leaving the coating on the vertical surfaces. The waveguide is then completed.
    Type: Grant
    Filed: September 9, 1994
    Date of Patent: March 19, 1996
    Assignee: AT&T Corp.
    Inventors: Raymond A. Cirelli, Charles H. Henry, Edward J. Laskowski, Michele A. Milbrodt, Henry H. Yaffe
  • Patent number: 5479551
    Abstract: In accordance with the invention, an optical fiber phase shifter comprises a length of asymmetrical optical fiber disposed perpendicular to a magnetic field for providing a non-reciprocal phase shift. Preferably the fiber is wound in a circular coil and exposed to an axial field as from a pancake magnet. In an isolator, the fiber length and magnet strength are chosen to provide non-reciprocal phase shifts of .+-.45.degree. or .+-.90.degree.. The isolator including the phase shifter can be any of several configurations.
    Type: Grant
    Filed: August 29, 1994
    Date of Patent: December 26, 1995
    Assignee: AT&T Corp.
    Inventors: David J. DiGiovanni, Kenneth L. Walker, Weyl-Kuo Wang, Raymond Wolfe
  • Patent number: 5478371
    Abstract: In accordance with the invention, the index of refraction of a region of a glass body is selectively increased by treating the material with hydrogen and then simultaneously applying heat and actinic radiation to the region. Preferably the body is heated to a temperature in excess of 150.degree. C. and the heat and radiation are simultaneously applied. The result is a substantial and long-lived increase in excess of 5.times.10.sup.-5 in the refractive index of the irradiated region. This process can be used to make and adjust a variety of optical waveguide devices such as photoinduced Bragg gratings.
    Type: Grant
    Filed: September 13, 1994
    Date of Patent: December 26, 1995
    Assignee: AT&T Corp.
    Inventors: Paul J. Lemaire, William A. Reed, Ashish M. Vengsarkar
  • Patent number: 5473720
    Abstract: Applicants have discovered that low pullout strength of optical fiber is attributable to volatile, unreacted monomers and impurities which result from the incomplete polymerization of liquid coating materials. They have further discovered that removing these unreacted liquids as by heating in air, heating in vacuum or by application of a solvent mixture improves fiber coating adhesion. By heating cured polymer-coated fiber in air at temperatures of 100.degree. C. or more, the fiber pullout strength is enhanced by 25% or more. This postcure heating can advantageously be clone off-line by placing loosely wound fiber in a heated oven. Alternatively, the postcure heating can be done on-line by reel-to-reel passage of the fiber through a heated furnace. Preferred temperatures are in the range 100.degree. C.-300.degree. C. Even greater enhancement of pullout strength can be effected by heating in vacuum or by solvent extraction.
    Type: Grant
    Filed: March 7, 1994
    Date of Patent: December 5, 1995
    Assignee: AT&T Corp.
    Inventors: Yussuf S. Ali, Darryl L. Brownlow, Howard E. Katz, Valerie J. Kuck, Marcia L. Schilling, Lloyd Shepherd
  • Patent number: 5473714
    Abstract: In accordance with the invention, an optical fiber system is provided with a tapered fiber device for filtering, wavelength shift detecting, or switching. Specifically, applicant has discovered that a multiclad single mode optical fiber with a fundamental mode cutoff can be tapered to form a compact component useful in optical fiber systems, e.g. a filter in telecommunications systems, a wavelength shift detector in sensing systems, or a switch in any optical system.
    Type: Grant
    Filed: April 29, 1994
    Date of Patent: December 5, 1995
    Assignee: AT&T Corp.
    Inventor: Ashish M. Vengsarkar
  • Patent number: 5473456
    Abstract: Applicants have discovered that films of conductively doped GaInO.sub.3 grown on substrates by sputter deposition have conductivity comparable to conventional wide band-gap transparent conductors while exhibiting superior light transmission, particularly in the green and blue wavelength regions of the visible spectrum. Substrate temperatures ranged from 100.degree. C. to 550.degree. C. in an argon-oxygen ambient of total pressure 4 mTorr to 20 mTorr with an optimal oxygen partial pressure in the range 0.5 to 2 mTorr.
    Type: Grant
    Filed: October 27, 1993
    Date of Patent: December 5, 1995
    Assignee: AT&T Corp.
    Inventors: Robert J. Cava, Jueinai R. Kwo, Gordon A. Thomas
  • Patent number: 5467415
    Abstract: In accordance with the invention, a polarization independent optical device is fabricated by building the waveguide structure on a silicon substrate, adding a reinforcing layer of glass and removing regions of the silicon substrate underlying the waveguide structure. Alternatively, a reinforcing layer of glass can be added after the silicon in removed. Removal of the silicon underlying the waveguide structure eliminates polarization dependent spectral effects by eliminating the source of compressive strain, and the resulting glass reinforced structures are sufficiently robust for practical applications.
    Type: Grant
    Filed: April 22, 1994
    Date of Patent: November 14, 1995
    Assignee: AT&T Corp.
    Inventor: Herman M. Presby
  • Patent number: 5464664
    Abstract: Applicants have discovered that gallium arsenide surfaces can be dry passivated without heating or ion bombardment by exposing them downstream to ammonia plasma formation. Specifically, a workpiece having exposed gallium arsenide surfaces is passivated by placing the workpiece in an evacuable chamber, evacuating in the chamber, generating an ammonia plasma removed from the immediate vicinity of the workpiece, and causing the plasma products to flow downstream into contact with the workpiece. Preferably the plasma gas pressure is 0.5 to 6.0 Torr, the substrate temperature is less than 100.degree. C. and the time of exposure is in excess of 5 min. The plasma should be generated at a location sufficiently removed from the workpiece that the workpiece surface is not bombarded with ions capable of damaging the surface (more than about 10 cm) and sufficiently close to the workpiece that reactive plasma products exist in the flow (within about 30 cm).
    Type: Grant
    Filed: March 1, 1994
    Date of Patent: November 7, 1995
    Assignee: AT&T IPM Corp.
    Inventors: Eray S. Aydil, Konstantinos P. Giapis, Richard A. Gottscho
  • Patent number: 5461308
    Abstract: The present inventors have discovered that a compact, highly sensitive current sensor can be made for any inductive component having an air gap in its magnetic path by disposing a layer of magnetoresistive material in the path of the fringing magnetic field. In the preferred embodiment, a thin magnetoresistive film of La.sub.w Ca.sub.x Mn.sub.y O.sub.z on a LaAlO.sub.3 /Al.sub.2 O.sub.3 substrate provides a high sensitivity in the range of 1-100 mV/ampere of DC current in the inductive component. The current sensor consumes a very small amount of power and provides the desirable electrical isolation between the sensor and the active device circuit.
    Type: Grant
    Filed: December 30, 1993
    Date of Patent: October 24, 1995
    Assignee: AT&T IPM Corp.
    Inventors: Sungho Jin, Mark T. McCormack, Apurba Roy, James C. Wadlington
  • Patent number: 5459097
    Abstract: In accordance with the invention, aluminum-containing layers are grown by molecular beam processes using as an arsenic precursor phenylarsine (PhAs). Because PhAs is more reactive than arsine and less reactive than arsenic, it decomposes selectively on III-V surfaces but not on mask materials. Thus in contrast to conventional processes, growth using PhAs permits selective growth on unmasked gallium arsenide surfaces but inhibits growth on typical mask materials such as silicon nitride.
    Type: Grant
    Filed: October 7, 1993
    Date of Patent: October 17, 1995
    Assignee: AT&T Corp.
    Inventors: Cammy R. Abernathy, Stephen J. Pearton, Fan Ren, Patrick W. Wisk
  • Patent number: 5457760
    Abstract: The present invention relates to methods and apparatus for wavelength division multiplexing (WDM) using arrays of optical filtering elements to create a desired wavelength passband in an optical filter. In one aspect of the invention, an optical demultiplexer is formed using an input waveguide, such as a planar waveguide or an optical fiber, coupled to plural output waveguides. Each output waveguide includes a wavelength selective configuration of optical filtering elements formed within a contiguous portion of the waveguide forming an optical channel-selective filter having spectral regions having an optical transmission passband and spectral regions of low transmissivity. Exemplary optical filtering elements are Bragg gratings formed into an optical filter which transmits a characteristic wavelength band.
    Type: Grant
    Filed: May 6, 1994
    Date of Patent: October 10, 1995
    Assignee: AT&T IPM Corp.
    Inventor: Victor Mizrahi
  • Patent number: 5450372
    Abstract: In accordance with the invention, a new type of microphone utilizes a magnetoresistive sensing element. Specifically, acoustical energy causes vibrations between a magnetoresistive element and a magnet, producing a variation in the resistance which can be used to convert an acoustical signal into a corresponding electrical signal.
    Type: Grant
    Filed: March 30, 1994
    Date of Patent: September 12, 1995
    Assignee: AT&T Corp.
    Inventors: Sungho Jin, Larry A. Marcus, Mark T. McCormack
  • Patent number: 5441013
    Abstract: In contrast to previous approaches, the present inventors have discovered that diamond films can be grown by carbon CVT reactions occurring exclusively in the exothermic regime, where the lower temperature (<1500.degree.C.) conditions considerably simplify the equilibrium gas phase chemistry. Under these conditions of a small temperature gradient and short transport distance between the source and substrate, supersaturation of the gas phase with regard to graphite and diamond does not attain sufficiently high values to induce spontaneous homonucleation of graphite and diamond in the gas phase. With this process, temperatures as low as 680.degree.C. were found to be sufficient to induce the growth of continuous diamond films free of non-diamond allotropes.
    Type: Grant
    Filed: March 23, 1993
    Date of Patent: August 15, 1995
    Assignee: AT&T Bell Laboratories
    Inventors: Guang-kai D. Jeng, James W. Mitchell, Lawrence Seibles