Patents Examined by James W. Davie
  • Patent number: 6418155
    Abstract: A laser device which repeats a cycle of burst mode operation in each of which continuous oscillating operations for continuously pulsatively oscillating laser light by a prescribed number of times and stopping operations for stopping the pulsative oscillation for a prescribed pausing time are alternately executed, controls the power supply voltage of the laser device so that each output energy of the pulsative oscillation can become coincide with a target value, finds the difference between the output voltage of each pulse and the target value at every pulse and, for a pulse for which the difference exceeds tolerance limits, corrects and updates the power supply voltage value stored in the voltage data table means corresponding to the pulse number of the pulse and the measured oscillation pausing time by using the control gain of a control gain setting means set in the block corresponding to the pulse number and the measured oscillation pausing time and the difference, so as to always make the pulse energy of
    Type: Grant
    Filed: June 17, 1999
    Date of Patent: July 9, 2002
    Assignee: Komatsu Ltd.
    Inventors: Osamu Wakabayashi, Tatsuya Ariga, Toru Igarashi, Shoichi Sakanishi, Tomokazu Takahashi
  • Patent number: 6408013
    Abstract: A semiconductor laser control method and a semiconductor laser control apparatus allow an outgoing radiation power of a semiconductor laser to be accurately stabilized to a desired value even if a characteristic of the semiconductor laser changes due to temperature variations or deterioration of life. The characteristic of a semiconductor laser is measured by a semiconductor laser characteristic detection unit and a target value is corrected by a target value correction unit based on a threshold current and differential quantum efficiency obtained from the measurement result. A power control unit controls the semiconductor laser by comparing the corrected target value with the output of a power detection unit, making it possible to achieve a desired outgoing radiation power of the semiconductor laser with high accuracy even if the threshold current or differential quantum efficiency of the semiconductor laser changes due to temperature variations or deterioration of life.
    Type: Grant
    Filed: April 6, 2000
    Date of Patent: June 18, 2002
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Toshiya Akagi, Yoshiyuki Miyabata
  • Patent number: 6404797
    Abstract: In an apparatus and method for generating high power laser radiation, the geometry of the resonant laser cavity defines a fundamental spatial or transverse cavity mode. A gain medium is disposed within the resonant cavity and an energy source energizes the gain medium within a first volume. This causes spontaneous and stimulated energy emission to propagate in the gain medium in a direction transverse to the fundamental cavity mode. The transverse emission in turn optically pumps a second volume of the gain medium about the first volume. When the intensity of the transverse emission is sufficiently high, inversion and gain are produced in the second volume. By optimizing the geometry of the cavity such that the fundamental cavity mode is coupled to both the first and the second volumes encompassing the first pumped volume, the transversely-directed energy of the first volume which would otherwise be wasted is instead captured by the fundamental beam, improving the overall power efficiently of the laser.
    Type: Grant
    Filed: September 30, 1999
    Date of Patent: June 11, 2002
    Assignee: Novalux, Inc.
    Inventor: Aram Mooradian
  • Patent number: 6404785
    Abstract: A solid state modulated ultraviolet laser comprises a laser diode for generating modulated optical energy, a waveguide upconversion laser for converting a portion of the modulated optical energy to upconversion optical energy, and a waveguide sum frequency generator for combining the modulated optical energy and the upconversion optical energy to generate a modulated ultraviolet signal.
    Type: Grant
    Filed: February 11, 1998
    Date of Patent: June 11, 2002
    Assignee: The United States of America as represented by the Secretary of the Navy
    Inventor: Richard Scheps
  • Patent number: 6404792
    Abstract: A light-emitting diode has a GaN-based multi-layer structure arranged on a sapphire substrate. A pair of electrode pads are arranged on a light-output face of the multi-layer structure. The first and second electrode pads have a total projected area set at 25% or less of that of the light-output face. The electrode pads are connected to electrode pads on a mount frame by solder wiring layers arranged on an insulating film covering the side wall of the multi-layer structure.
    Type: Grant
    Filed: May 30, 2001
    Date of Patent: June 11, 2002
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masahiro Yamamoto, Hidetoshi Fujimoto, Shin-ya Nunoue
  • Patent number: 6400737
    Abstract: A closed-loop feedback control system with a temperature tuned, wavelength stabilized laser module. The system uses a feedback control signal dependent upon a predetermined gain to control the temperature of the laser module. The laser module has an output connected to a controller via filtering and reference circuitry. The controller inputs etalon and reference signals from the filtering and reference circuitry to monitor the optical amplitude and wavelength of the laser module output, as well as the temperature of the laser module. When the controller detects a change in a slope of the etalon signal, the controller calculates a new numeric gain based on the changed slope. The new numeric gain and temperature of the laser module is used to generate a new control signal to maintain the output of the laser module at a desired wavelength. By monitoring the slope of the etalon signals, the system is capable of performing automatic closed-loop gain adjustment.
    Type: Grant
    Filed: December 14, 1999
    Date of Patent: June 4, 2002
    Assignee: Agere Systems Guardian Corp.
    Inventors: Scott L. Broutin, John W. Stayt, Jr.
  • Patent number: 6400736
    Abstract: The invention is an apparatus including a semiconductor laser device emitting light at least at a certain wavelength, and at least two reflectors external to the laser device and positioned to reflect the light to stabilize the wavelength.
    Type: Grant
    Filed: October 5, 1999
    Date of Patent: June 4, 2002
    Assignee: Agere Systems Guardian Corp.
    Inventors: Thomas Patrick Aherne, Charles Howard Henry, Rudolf Feodor Kazarinov, Carl E Soccolich
  • Patent number: 6400740
    Abstract: A support structure for the mounting of laser diode arrays, to facilitate the pumping of a suitably-shaped lasing medium, is constituted by a non-planar, preferably generally annularly-shaped, thermally conductive portion having an outer surface and an inner surface, the inner surface being shaped to accommodate an appropriate number of laser diode arrays to pump the medium. The outer surface may have cooling fins provided on the outside to facilitate the removal of heat from the vicinity of the laser diode arrays. Axial or circumferential cooling passages may be provided to facilitate removal of heat from the vicinity of the lasing medium, as well as the arrays. The lasing medium also may be surrounded by a cooling tube through which coolant flows, to facilitate removal of heat from the vicinity of the lasing medium in particular.
    Type: Grant
    Filed: October 21, 1999
    Date of Patent: June 4, 2002
    Assignee: Laser Diode Array, Inc.
    Inventor: Arthur A. Karpinski
  • Patent number: 6396861
    Abstract: An n-type modulation-doped multi quantum well semiconductor laser device having a multi quantum well structure composed of a hetero-junction structure including well layers and barrier layers, characterized in that each of the well layers and each of the barrier layers are formed of an undoped semiconductor material and a semiconductor material modulation-doped with an n-type dopant, respectively, an anti-reflection film and a high-reflection film are formed on the front and rear facets, respectively, the resonator length is not shorter than 800 &mgr;m, and mirror loss (&agr;m) given by &agr;m=(1/2L)ln{1/(Rf×Rr)}, where L, Rf and Rr are the cavity length (cm), reflectance of the front facet, and reflectance of the rear facet, respectively, is not higher than 15 cm−1. The output of this laser device is higher than that of a conventional undoped MQW semiconductor laser device.
    Type: Grant
    Filed: October 8, 1999
    Date of Patent: May 28, 2002
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Hitoshi Shimizu, Kouji Kumada, Akihiko Kasukawa
  • Patent number: 6396865
    Abstract: A vertical cavity surface emitting semiconductor laser is formed with a multilayer structure on a semiconductor substrate that includes an active region layer, a central core, and an antiresonant reflecting waveguide ring surrounding the central core. The ring includes a region formed to have an effective higher index than the central core and sized to provide antiresonant lateral waveguiding confinement of a fundamental mode wavelength. Reflectors formed above and below the active region layer provide vertical confinement. The antiresonant reflecting ring may be formed either as a full ARROW structure including a quarter wavelength high effective index region and a quarter wavelength low effective index region or as a simplified ARROW structure having a single quarter wavelength high effective index region.
    Type: Grant
    Filed: October 27, 2000
    Date of Patent: May 28, 2002
    Assignee: Wisconsin Alumni Research Foundation
    Inventors: Luke J. Mawst, Delai Zhou
  • Patent number: 6396856
    Abstract: The present invention is directed to methods and apparatuses for performing temporal scanning using ultra-short pulsewidth lasers in which only minimal (micro-scale) mechanical movement is required. The invention also relates to methods for obtaining high-accuracy timing calibration, on the order of femtoseconds. A dual laser system is disclosed in which the cavity of one or more of the lasers is dithered, by using a piezoelectric element. A Fabry-Perot etalon is used to generate a sequence of timing pulses used in conjunction with a laser beam produced by the laser having the dithered laser cavity. A correlator correlates a laser pulse from one of the lasers with the sequence of timing pulses to produce a calibrated time scale.
    Type: Grant
    Filed: March 27, 1998
    Date of Patent: May 28, 2002
    Assignee: Irma America, Inc.
    Inventors: Gregg D. Sucha, Martin E. Fermann, Donald J. Harter
  • Patent number: 6396860
    Abstract: An optically-pumped laser having a small-molecule thin organic film of DCM doped Alq3. Carrier transport properties of the small-molecule organic materials, combined with a low lasing threshold provide a new generation of diode lasers employing organic thin films. An electrically-pumped variant is also described.
    Type: Grant
    Filed: August 25, 2000
    Date of Patent: May 28, 2002
    Assignee: The Trustees of Princeton University
    Inventors: Vladimir Kozlov, Stephen R. Forrest, Paul Burrows, Vladimir Bulovic
  • Patent number: 6393041
    Abstract: Disclosed is an apparatus for controlling a semiconductor laser module wherein despite an increase in laser driving current owing to aging of the laser module, temperature control can be performed accurately so as to render constant the actual temperature of the laser module and prevent a change in lasing wavelength that accompanies a change in temperature. The apparatus includes a photodiode for sensing optical intensity of the laser; an APC circuit for controlling driving current of the laser in accordance with an output from the photodiode; a thermistor for sensing the temperature of the laser module; an ATC circuit for driving an electronic laser-cooling device in accordance with an output from the thermistor; and a current-quantity sensing circuit, which is connected to the APC and ATC circuits, for sensing the driving current of the laser output from the APC circuit.
    Type: Grant
    Filed: April 26, 2000
    Date of Patent: May 21, 2002
    Assignee: NEC Corporation
    Inventor: Kazuyoshi Sato
  • Patent number: 6389049
    Abstract: A discharge circuit for pulsed laser comprising a power source, main discharge electrodes for generating a laser beam, a main discharge capacitor charged with electrical charges for generating the main discharge between the main discharge electrodes, and a switching circuit for performing switching operations to charge the main discharge capacitor with electrical charges supplied from the power source in a prescribed repetition cycle, is provided, in parallel to the main discharge capacitors, with a circuit element for consuming or grounding the reverse current from the power source caused by overshoot generated directly after the main discharge, thereby attaining stable laser output without ill effects from overshoot voltage generated directly following discharge.
    Type: Grant
    Filed: October 5, 1998
    Date of Patent: May 14, 2002
    Assignees: Komatsu Ltd., Kabushiki Kaisha Meidensha
    Inventors: Daisuke Yoshida, Toshihiro Nishisaka, Yuichi Takabayashi, Takashi Matsunaga, Hisashi Yanase, Tadao Shibuya, Yasuo Kataoka, Masayuki Tani, Eiji Sasamoto, Hiroyuki Hiyoshi, Kiyoshi Hara
  • Patent number: 6389051
    Abstract: A structure and method for an asymmetric waveguide nitride laser diode without need of a p-type waveguide is disclosed. The need for a high aluminum tunnel barrier layer in the laser is avoided.
    Type: Grant
    Filed: June 30, 1999
    Date of Patent: May 14, 2002
    Assignee: Xerox Corporation
    Inventors: Christian G. Van de Walle, David P. Bour, Michael A. Kneissl, Linda T. Romano
  • Patent number: 6385220
    Abstract: A laser clamping system for a disc laser medium that includes two heat conductive members (one of which is optically transparent) positioned on either side of a disc laser. Pressure is applied to the conductive members to restrain the disc from deforming under pumping conditions to reduce the lensing effect. Thin disc geometry allows the thermal load of laser material to be much closer to the heat conductive members so that heat dissipation is generally more efficient than that of other geometric configurations (e.g. rod or slab). In disc lasers each part of the laser beam experiences the same temperature gradient so that there is no lensing effect caused by radial temperature distribution. It has been discovered that any resulting lensing effect is disc lasers is mainly from the thermo-mechanical deformation of the disc itself.
    Type: Grant
    Filed: April 21, 1999
    Date of Patent: May 7, 2002
    Assignee: GSI Lumonics Inc.
    Inventors: Robert John Dwayne Miller, Yan Liao, Michael Robert Armstrong, David Ronald Walker
  • Patent number: 6385224
    Abstract: An edge emitting laser comprising a substrate with or without a buffer layer having a central mesa disposed thereon, said central mesa having a bottom surface, a top surface and side surfaces and said mesa having an active layer disposed on said substrate with or without a buffer layer, a cladding layer disposed on said active layer, and a quaternary layer disposed on said cladding layer; first and second blocking layers disposed along said sides of said mesa; and at least one alignment fiducial disposed along an outer region of the laser, said alignment fiducial comprising at least a first surface and a second surface, said first surface being a certain distance from said active layer in the y-direction and said second surface being a certain distance from said active layer in the x-direction, said first surface comprising at least a portion of the top of said quaternary layer, said second surface comprising at least a portion of a side of at least one of said quaternary, cladding, or active layers.
    Type: Grant
    Filed: March 29, 1999
    Date of Patent: May 7, 2002
    Assignee: The Whitaker Corporation
    Inventors: Ching-Long Jiang, Randall Brian Wilson, Mark Rafael Soler
  • Patent number: 6385216
    Abstract: An optical fiber mode-locked laser is disclosed. The laser comprises a gain medium doped optical fiber to achieve a population inversion between high and low energy levels by a pump light source and to oscillate optical waves in sequence, a cholesteric liquid crystal circular polarization mirror to transmit the waves from the pump light source and to be operated as a circular polarization reflection mirror for the oscillated optical waves from the gain medium doped optical fiber, a polarization controller to control the polarization state of the proceeding light which is oscillated from the gain medium doped optical fiber, a dispersion shifted fiber to give a non-linear effect to the proceeding light through the polarization controller, and an optical fiber laser output mirror which forms a resonator by putting out some portion of the proceeding light by transmission and reflecting the other portion of the light.
    Type: Grant
    Filed: November 12, 1999
    Date of Patent: May 7, 2002
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Do Il Chang, Ho Young Kim, Kyong Hon Kim, Min Yong Jeon
  • Patent number: 6385222
    Abstract: The present invention relates to a semiconductor laser module and a method for driving the same, wherein an overcurrent limiting means which suppresses the overcurrent to the thermomodule is provided, and it is possible to prevent abnormally high temperature heat being generated from the thermomodule, originating from the overcurrent flow in the heating direction to the thermomodule. Therefore, it is possible to avoid various problems which include thermal breakage of the thermomodule itself, thermal breakage of components such as semiconductor laser elements, etc., thermally connected to the thermomodule, a slip in optical coupling due to a positional deviation of the components originating from high temperature heat, an optical coupling loss, etc. Therefore, the reliability of optical coupling and durability of the semiconductor laser module can be further improved.
    Type: Grant
    Filed: November 19, 1999
    Date of Patent: May 7, 2002
    Assignee: The Furukawa Electric Co., Ltd.
    Inventor: Takeshi Aikiyo
  • Patent number: 6381257
    Abstract: A tunable injection seeded very narrow band F2 lithography laser. The laser combines modular design features of prior art long life reliable lithography lasers with special techniques to produce a seed beam operated in a first gain medium which beam is used to stimulate narrow band lasing in a second gain medium to produce a very narrow band laser beam useful for integrated circuit lithography. In a preferred embodiment, two tunable etalon output couplers are used to narrow band an F2 laser and the output of the seed laser is amplified in an F2 amplifier.
    Type: Grant
    Filed: December 28, 1999
    Date of Patent: April 30, 2002
    Assignee: Cymer, Inc.
    Inventors: Alexander I. Ershov, Eckehard D. Onkels, Palash P. Das, William N. Partlo, Thomas Hofmann