Patents by Inventor Walter M. Duncan

Walter M. Duncan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6917467
    Abstract: A programmable amplifier 100 operable to independently adjust the amplification given to various optical signals passing through an optical fiber. An input optical fiber 102 provides a number of optical signals to a demultiplexer which separates each signal carried by the input fiber 102. Each individual wavelength travels to a variable attenuator 106 which lowers the signal strength of each signal based on an input from the system controller 108. The attenuated signals are combined by multiplexer 112 and input to an optical amplifier 114. The optical amplifier 114 receives the combined signal and amplifies each signal in the combined DWDM signal across the entire bandwidth of the amplifier 114. The amplified signals are input to a splitter 116 which removes a small portion of the entire spectrum output by the amplifier 114. The remaining portion of the signal passes to an output fiber 110 and travels to the remainder of the optical network.
    Type: Grant
    Filed: January 22, 2002
    Date of Patent: July 12, 2005
    Assignee: Texas Instruments Incorporated
    Inventors: Thomas Russell Howell, Walter M. Duncan, Paul L. Rancuret
  • Patent number: 6746886
    Abstract: A process for protecting a MEMS device used in a UV illuminated application from damage due to a photochemical activation between the UV flux and package gas constituents, formed from the out-gassing of various lubricants and passivants put in the device package to prevent sticking of the MEMS device's moving parts. This process coats the exposed surfaces of the MEMS device and package's optical window surfaces with a metal-halide film to eliminate this photochemical activation and therefore significantly extend the reliability and lifetime of the MEMS device.
    Type: Grant
    Filed: March 18, 2002
    Date of Patent: June 8, 2004
    Assignee: Texas Instruments Incorporated
    Inventors: Walter M. Duncan, Simon Joshua Jacobs, Michael R. Douglass, Richard O. Gale
  • Publication number: 20030016337
    Abstract: A process for protecting a MEMS device used in a UV illuminated application from damage due to a photochemical activation between the UV flux and package gas constituents, formed from the out-gassing of various lubricants and passivants put in the device package to prevent sticking of the MEMS device's moving parts. This process coats the exposed surfaces of the MEMS device and package's optical window surfaces with a metal-halide film to eliminate this photochemical activation and therefore significantly extend the reliability and lifetime of the MEMS device.
    Type: Application
    Filed: March 18, 2002
    Publication date: January 23, 2003
    Inventors: Walter M. Duncan, Simon Joshua Jacobs, Michael R. Douglass, Richard O. Gale
  • Publication number: 20020118443
    Abstract: A programmable amplifier 100 operable to independently adjust the amplification given to various optical signals passing through an optical fiber. An input optical fiber 102 provides a number of optical signals to a demultiplexer which separates each signal carried by the input fiber 102. Each individual wavelength travels to a variable attenuator 106 which lowers the signal strength of each signal based on an input from the system controller 108. The attenuated signals are combined by multiplexer 112 and input to an optical amplifier 114. The optical amplifier 114 receives the combined signal and amplifies each signal in the combined DWDM signal across the entire bandwidth of the amplifier 114. The amplified signals are input to a splitter 116 which removes a small portion of the entire spectrum output by the amplifier 114. The remaining portion of the signal passes to an output fiber 110 and travels to the remainder of the optical network.
    Type: Application
    Filed: January 22, 2002
    Publication date: August 29, 2002
    Inventors: Thomas Russell Howell, Walter M. Duncan, Paul L. Rancuret
  • Publication number: 20020079432
    Abstract: A method for assuring a blazed condition in a DMD device used in telecommunications applications. By meeting certain conditions in the fabrication and operation of the DMD, the device can achieve a blazed condition and be very effective in switching near monochromatic spatially coherent light, thereby opening up a whole new application field for such devices. This method determines the optimal pixel pitch and mirror tilt angle for a given incident angle and wavelength of near monochromatic spatially coherent light to assure blazed operating conditions. The Fraunhofer envelope is determined by convolving the Fourier transforms of the mirror aperture and the delta function at the center of each mirror and then aligning the center of this envelope with a diffraction order to provide a blazed condition.
    Type: Application
    Filed: August 7, 2001
    Publication date: June 27, 2002
    Inventors: Benjamin L. Lee, Claude E. Tew, Walter M. Duncan
  • Patent number: 5756375
    Abstract: Molecular beam epitaxy (202) with growing layer thickness and doping control (206) by feedback of sensor signals such as spectrosceopic ellipsometer signals based on a process model. Examples include III-V compound structures with multiple AlAs, InGaAs, and InAs layers as used in resonant tunneling diodes and hetrojunction bipolar transistors with doped and undoped GaAs layers, AlGaAs and InGaAs.
    Type: Grant
    Filed: June 14, 1996
    Date of Patent: May 26, 1998
    Assignee: Texas Instruments Incorporated
    Inventors: Francis G. Celii, Walter M. Duncan, Tae S. Kim
  • Patent number: 5552667
    Abstract: A method and apparatus for producing photoluminescence emissions (68) from thin CaF.sub.2 films grown on either silicon or silicon/aluminum substrate shows narrow emission linewidth and high emission intensities for CaF.sub.2 with thickness as low as 0,2 .mu.m, The preferred embodiment is doped with a rare-earth such as Nd.
    Type: Grant
    Filed: April 17, 1995
    Date of Patent: September 3, 1996
    Assignee: Texas Instrument Incorporated
    Inventors: Chin-Chen Cho, Tsen H. Lin, Shou-Kong Fan, Walter M. Duncan
  • Patent number: 5501637
    Abstract: A direct, noncontact temperature sensor includes an ellipsometer (104-106) to determine absorptance for layered structures and a pyrometer (102) to determine emissive power and combines the two measurements to determine temperature.
    Type: Grant
    Filed: September 20, 1994
    Date of Patent: March 26, 1996
    Assignee: Texas Instruments Incorporated
    Inventors: Walter M. Duncan, Francis G. Celii, Steven A. Henck, Ajit P. Paranjpe, Douglas L. Mahlum, Larry A. Taylor
  • Patent number: 5494850
    Abstract: This invention discloses a method to improve significantly the optical properties of rare-earth doped MBE-grown CaF.sub.2 films by annealing such films in a reducing atmosphere (e.g. forming gas) at appropriate temperatures (generally greater than 600 C. Films grown at the same temperature as that used later in the novel annealing process do not exhibit the same PL spectrum nor the high photoluminescence intensity emissions as annealed films. The intensity of the strongest peak 12a in FIG. 2 has a magnitude 3.6 times the intensity than the strongest peak 12 in as-grown film in FIG. 1. Similarly these same films annealed in an oxygen environment do not exhibit the have the desired properties.
    Type: Grant
    Filed: March 1, 1994
    Date of Patent: February 27, 1996
    Assignee: Texas Instruments Incorporated
    Inventors: Chih-Chen Cho, Walter M. Duncan
  • Patent number: 5369657
    Abstract: A silicon-based microlaser formed of rare-earth-doped CaF.sub.2 thin films has a semiconductor substrate material (240) and a CaF.sub.2 film layers (234) grown on semiconductor substrate material (240), The CaF.sub.2 film layer (234) is doped with a predetermined amount of rare-earth-dopant that is sufficient to cause a spectral emission from the CaF.sub.2 film layer (234) having a narrow linewidth when the CaF.sub.2 film layer (234) is optically or electrically pumped.
    Type: Grant
    Filed: September 15, 1992
    Date of Patent: November 29, 1994
    Assignee: Texas Instruments Incorporated
    Inventors: Chih-Chen Cho, Walter M. Duncan
  • Patent number: 5306385
    Abstract: A method and apparatus for producing photoluminescence emissions (68) from thin CaF.sub.2 films grown on either silicon or silicon/aluminum substrate shows narrow emission linewidth and high emission intensities for CaF.sub.2 with thickness as low as 0.2 .mu.m. The preferred embodiment is doped with a rare-earth such as Nd.
    Type: Grant
    Filed: September 30, 1992
    Date of Patent: April 26, 1994
    Assignee: Texas Instruments Incorporated
    Inventors: Chih-Chen Cho, Tsen H. Lin, Shou-Kong Fan, Walter M. Duncan
  • Patent number: 5301204
    Abstract: A method and apparatus (242) generates intense spectral emissions (68) by associating a porous-Si layer (230) with a rare earth-doped CaF.sub.2 film (234) so that the rare earth-doped CaF.sub.2 film absorbs optical emissions (222) from the porous-Si layer (230). Circuitry (228, 244, and 238) associated with the apparatus (242 and 226) activate the porous-Si layer (230) to produce the optical emissions (222). The porous-Si layer (230) may be formed electrically, by chemical vapor deposition, or by anodizing crystalline silicon.
    Type: Grant
    Filed: September 30, 1992
    Date of Patent: April 5, 1994
    Assignee: Texas Instruments Incorporated
    Inventors: Chih-Chen Cho, Walter M. Duncan
  • Patent number: 5249865
    Abstract: An interferonmetric temperature measurement system is described for determining the temperature of a sample. The system comprises three detectors for measuring various intensities of a beam of electromagnetic radiation reflected off the sample and circuitry for determining the temperature from the intensities. The detectors measure the intensity of the beam and two orthogonally polarized components of the beam.
    Type: Grant
    Filed: April 27, 1992
    Date of Patent: October 5, 1993
    Assignee: Texas Instruments Incorporated
    Inventors: Ajit P. Paranjpe, Steven A. Henck, Walter M. Duncan
  • Patent number: 4743569
    Abstract: A two step rapid thermal anneal (RTA) has been studied for activating Be implanted GaAs, where a short duration high temperature step is used to electrically activate the Be followed by a longer low temperature anneal for lattice re-growth. PN diodes show a substantial reduction in reverse diode leakage current after the lower temperature second step anneal, when compared to a single step RTA or to furnace annealing (FA). For low energy Be implants, no difference in electrical activation between the single step and the two step anneal is observed. Raman studies demonstrate that residual substrate impurities and high Be concentrations inhibit restoration of single crystal lattice characteristics after RTA. Lattice quality is also shown not to limit diode characteristics in the RTA material.
    Type: Grant
    Filed: April 20, 1987
    Date of Patent: May 10, 1988
    Assignee: Texas Instruments Incorporated
    Inventors: Donald L. Plumton, Liem T. Tran, Walter M. Duncan
  • Patent number: 4654960
    Abstract: Bipolar transistors and other electronic structures are fabricated on a gallium arsenide (GaAs) substrate to form an integrated circuit device. This process is made possible by development of an ion implant technique which uses an acceptor material to create a P type region, boron or protons to create insulating regions, and silicon or selenium to create an N type region. The process avoids the difficult problems encountered in diffusion methods, and, due to the precise control available with the ion implant method, makes possible the fabrication of IC quality transistors consistently over a substrate. This same control enables the fabrication of integrated circuits with improved device packing density and reduced parasitic parameters.
    Type: Grant
    Filed: December 13, 1985
    Date of Patent: April 7, 1987
    Assignee: Texas Instruments Incorporated
    Inventors: William V. McLevige, Han-Tzong Yuan, Walter M. Duncan, Friedrich H. Doerbeck
  • Patent number: 4573064
    Abstract: Bipolar transistors and other electronic structures are fabricated on a gallium arsenide (GaAs) substrate to form an integrated circuit device. This integrated circuit device is made possible by development of an ion implant technique which uses an acceptor material to create a P type region, boron or protons to create insulating regions, and silicon or selenium to create an N type region. The use of an ion implant technique avoids the difficult problems encountered in diffusion methods, and, due to the precise control available with ion implantation, makes possible the fabrication of IC quality transistors consistently over a substrate. This same control enables the fabrication of integrated circuits with improved device packing density and reduced parasitic parameters.
    Type: Grant
    Filed: November 2, 1981
    Date of Patent: February 25, 1986
    Assignee: Texas Instruments Incorporated
    Inventors: William V. McLevige, Han-Tzong Yuan, Walter M. Duncan, Friedrich H. Doerbeck