Particular Operating Compensation Means Patents (Class 372/33)
  • Patent number: 6151344
    Abstract: Automatic power control of a semiconductor laser (12, 72) is achieved by monitoring the spontaneous lateral emissions from the semiconductor laser and adjusting the drive signal to the laser based on the detected emissions. A lateral detector (13, 73) generates a photocurrent from the spontaneous emissions. The detector signal (Ilat) is compared to a reference signal (Iref) and the difference is applied to the drive signal (Ilas) to alter or control the laser output. The magnitudes of the reference signal source and the drive signal source are determined and set based on the desired optical output power of the semiconductor laser measured at a series of temperatures.
    Type: Grant
    Filed: March 30, 1998
    Date of Patent: November 21, 2000
    Assignee: Motorola, Inc.
    Inventors: Philip Kiely, Paul R. Claisse
  • Patent number: 6144684
    Abstract: A laser diode array assembly includes a laser diode array and a memory device integrally packaged with the array. The memory device includes operational information concerning the array. The memory device is accessible by a host external operating system which determines the manner in which the array is to be powered based on the operational information. The memory device may have the capability to be written to such that the external operating system can record in the memory device significant events such as extreme operational conditions, operational faults, and the on-time or shot-count of the array. The assembly may include sensors to which the operating system is coupled. The assembly may further include a processing means to monitor the sensors and provide real-time updates to the external operating system such that laser diode array is continuously powered in an optimal manner.
    Type: Grant
    Filed: March 27, 1998
    Date of Patent: November 7, 2000
    Assignee: Cutting Edge Optronics, Inc.
    Inventors: Theodore S. McMinn, Dana A. Marshall, Michael A. Hope, Geoffrey O. Heberle
  • Patent number: 6137814
    Abstract: The invention relates to a light emitter device comprising an integrated component having a laser section provided with an oscillator section designed to supply a laser wave, and a modulator section. In order to control the light frequency of the emitted modulated wave, an electronic circuit controls the current of the laser section in response to a measurement of the amplitude of the modulation of the voltage induced across the terminals of the laser section by the modulation section.
    Type: Grant
    Filed: November 5, 1998
    Date of Patent: October 24, 2000
    Assignee: Alcatel
    Inventors: Philippe Brosson, Alexis Lestra, Jean-Paul Hebert
  • Patent number: 6134253
    Abstract: An apparatus for monitoring and controlling the wavelength of laser radiation includes at a least one optical filter for receiving laser radiation and for transmitting and reflecting first and second filtered beams, respectively. The beams are filtered according to respective first and second spectral filter functions that cross at least one crossing wavelength. A beam comparing element compares the intensities of the first and second filtered beams and produces an error signal responsive to the deviation of the wavelength of the laser radiation from a set point wavelength. The beam comparing element can include first and second optical detectors and an error circuit for producing the error signal by taking a ratio or the difference of the signals detected by the detectors. Varying the angle of incidence of the laser radiation upon at least one optical filter varies the spectral filter function of that for selecting or varying the operating wavelength of the laser.
    Type: Grant
    Filed: February 19, 1998
    Date of Patent: October 17, 2000
    Assignee: JDS Uniphase Corporation
    Inventors: Timothy C. Munks, Paul E. Dunn, David J. Allie
  • Patent number: 6122302
    Abstract: A laser transmitter used in an optical communication system provides automatic compensation/stabilization of CNR (carrier to noise ratio) and OMI (optical modulation index) in conditions that would have caused these parameters to change if the compensation circuitry was not employed. The compensation circuitry is an open loop that operates in conjunction with a conventional APC (automatic power control) loop. When certain parameters change (i.e., temperature, laser aging, intentional change in optical power) they will affect the laser DC current (either directly or because of the existence of the APC loop) and as a result the CNR/OMI will change. The compensation circuitry senses the change in the laser DC current and changes the modulating current to the laser as required to minimize changes in CNR/OMI.
    Type: Grant
    Filed: December 10, 1997
    Date of Patent: September 19, 2000
    Assignee: Harmonic Inc.
    Inventor: Alon Dean
  • Patent number: 6115397
    Abstract: In a laser system which produces radiation which is highly absorbed by water, the pump voltage supplied to the laser rod is slowly increased between the lasing threshold voltage and the full operational voltage of the pump. As a result, the output energy and circulating energy of the system slowly increase, such that any water on the intracavity coatings is vaporized slowly, rather than explosively. The laser system and method of using same thus reduce or prevent damage to the intracavity coatings used within the laser cavity.
    Type: Grant
    Filed: April 21, 1999
    Date of Patent: September 5, 2000
    Assignee: Hoya Photonics, Inc.
    Inventors: Jean-Marc Heritier, Francois Moya
  • Patent number: 6115398
    Abstract: Automatic power control (APC) of a semiconductor laser array is achieved by monitoring the backward emission emitted by a plurality of semiconductor devices which compose the semiconductor laser array. The drive signal to the laser is adjusted based on the detected emissions. A photosensor mounted in a submount, to which the semiconductor laser array is mounted, is positioned to receive a photocurrent from the backward emissions. A sweeping injection current across the laser array provides for the sequential detection of the backward emission and thus provides for automatic power control (APC).
    Type: Grant
    Filed: May 18, 1998
    Date of Patent: September 5, 2000
    Assignee: Motorola, Inc.
    Inventor: Wenbin Jiang
  • Patent number: 6111903
    Abstract: An optical emission device includes a laser source having an emitting surface, and a sensor laterally adjacent the laser source generating an output signal dependent on the amount of light falling on its detection surface. A transparent waveguide is located in front of the emitting surface and extends generally parallel thereto such that light striking the waveguide in a direction normal to the emitting surface passes straight through the waveguide. A coupling medium is placed between the emitting surface and the waveguide. A light dispersant in the coupling medium causes a fraction of the laser light to strike the waveguide at an oblique angle so that it can enter the waveguide and be carried thereby to the sensor. An important advantage of the invention is that is uses inexpensive passive parts. The assembly process easy to implement, and the parts are stable during temperature changes. As a result only a small tracking error occurs.
    Type: Grant
    Filed: June 24, 1998
    Date of Patent: August 29, 2000
    Assignee: Mitel Semiconductor AB
    Inventors: Jan Isaksson, Michael Widman
  • Patent number: 6111901
    Abstract: There is provided a semiconductor laser driving circuit. The circuit has: an amplifier for receiving an emission level setting voltage, and outputting a first driving signal on the basis of the emission level setting voltage; a driving signal generation circuit for receiving a control signal for instructing a light-emission period of a semiconductor laser, and the first driving signal output from said amplifier, and outputting a second driving signal corresponding to a level of the first driving signal in accordance with a light-emission or extinction period; a driving circuit for receiving the second driving signal output from said driving signal generation circuit, and generating and outputting a driving current to be supplied to the semiconductor laser; and a control circuit for receiving the emission level setting voltage, and adjusting a level of the second driving signal during the extinction period in correspondence with the emission level setting voltage.
    Type: Grant
    Filed: September 10, 1998
    Date of Patent: August 29, 2000
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toyoki Taguchi, Masayuki Tazawa
  • Patent number: 6104734
    Abstract: In order to eliminate noise of a solid state laser apparatus generating a blue light wave, the solid state laser apparatus comprises a solid state laser light source, an optical modulator having a light modulating function and outputting the modulated light therefrom as a desired light output, a photo-detector converting one part of output light from the solid state laser light source to an electrical signal, an electrical circuit detecting a noise component from the electrical signal and moving the phase of an electrical signal corresponding to the noise component, and a controller for applying the output signal of the electrical circuit to the optical modulator so as to substantially eliminate light of the blue light wave corresponding to the noise component so as to provide the desired light output from the optical modulator.
    Type: Grant
    Filed: June 3, 1999
    Date of Patent: August 15, 2000
    Assignees: Hitachi, Ltd., Hitachi Metals, Ltd.
    Inventors: Tadao Ino, Hirofumi Sukeda, Hideki Saga, Hiroshi Toyama, Tsuyoshi Miyai
  • Patent number: 6091747
    Abstract: A laser diode drive circuit comprising a laser diode; a drive pulse current source for emitting light or not emitting light of the laser diode according to an input signal; and a biasing unit for optimally operating the laser diode, the biasing unit having a bias voltage source for applying a bias voltage to the laser diode, which bias voltage can feed an optimum bias current to the laser diode. The laser diode drive circuit can maintain a bias current at a predetermined value with high precision and with high stability.
    Type: Grant
    Filed: September 24, 1997
    Date of Patent: July 18, 2000
    Assignee: Fujitsu Limited
    Inventors: Takayoshi Morita, Akira Nagayama
  • Patent number: 6088373
    Abstract: A hybrid tunable Bragg laser including a double heterostructure gain section, a Bragg reflector section optically coupled to said gain section, and an optical extension constructed to yield a plurality of longitudinal modes. Preferably, the optical section has a predetermined length and effective reflectivity adapted to yield the plurality of longitudinal modes.
    Type: Grant
    Filed: February 17, 1999
    Date of Patent: July 11, 2000
    Assignee: Lucent Technologies Inc.
    Inventor: Basil Wahid Hakki
  • Patent number: 6084897
    Abstract: A burst-on/off signal transmitting means which generates a burst-on signal for starting continuous-wave oscillation of a laser and a burst-off signal for starting stopping the continuous-wave oscillation and transmits the signals to the laser is provided on the processing device side. Control means which receives the burst-on/off signals and controls burst operation by using the signal is provided on the laser side. The charging control is not needed while the laser does not oscillate. Therefore, the safety of the laser is ensured. The output of the laser is controlled to a fixed level with high accuracy, and the responsivenesses of the other controls and the control speed are improved.
    Type: Grant
    Filed: February 26, 1998
    Date of Patent: July 4, 2000
    Assignee: Komatsu, Ltd.
    Inventors: Osamu Wakabayashi, Tetsuo Shakushi
  • Patent number: 6081539
    Abstract: A tunable laser source apparatus includes an external cavity. The external cavity includes a semiconductor laser and a diffraction section. At least one laser output end facet of the semiconductor laser is covered with an AR coating. The diffraction section includes a first reflector and a diffraction grating, and has wavelength selectivity with which light emerging from the end facet of the semiconductor laser which is covered with the AR coating is received, and light having a predetermined wavelength is selected and reflected toward the semiconductor laser. The semiconductor laser further includes an angle detection section and a control section. The angle detection section detects the angle defined by the optical path of the light emerging from the semiconductor laser and the optical path of the diffracted light reflected by the diffraction section.
    Type: Grant
    Filed: March 30, 1999
    Date of Patent: June 27, 2000
    Assignee: Anritsu Corporation
    Inventors: Shigenori Mattori, Shigeru Kinugawa, Takanori Saitoh
  • Patent number: 6069730
    Abstract: A system and method for monitoring the mode of an input beam to a phase conjugated master oscillator power amplifier (PC MOPA). In order to prevent catastrophic optical damage to the MOPA components, the method and system shuts down the master oscillator when a multi-mode input beam is detected.
    Type: Grant
    Filed: August 14, 1998
    Date of Patent: May 30, 2000
    Assignee: TRW Inc.
    Inventors: Hagop Injeyan, Randall J. St. Pierre, Mark E. Weber
  • Patent number: 6069904
    Abstract: A light generating apparatus includes: a submount; a semiconductor laser chip mounted on the submount; a substrate which is mounted on the submount and includes an optical waveguide; and a substance having a predetermined thickness which is disposed between the semiconductor laser chip and the substrate. In an oscillation wavelength stabilizing apparatus for a light source, the light source is a semiconductor laser which includes: an active region for providing gain; and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength. The apparatus includes a control section which monotonously varies, in a first direction, a DBR current to be input to the DBR region while detecting the oscillation wavelength of an output light of the semiconductor laser so as to detect a DBR current value I.sub.0 corresponding to a predetermined wavelength value, and then monotonously varies the DBR current in a second direction which is opposite the first direction beyond the detected value I.sub.
    Type: Grant
    Filed: August 12, 1997
    Date of Patent: May 30, 2000
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Yasuo Kitaoka, Kazuhisa Yamamoto, Makoto Kato, Tomoaki Uno, Kiminori Mizuuchi, Kenichi Nishiuchi
  • Patent number: 6064472
    Abstract: A method for speed measurement according to the laser-Doppler-principle with which with the help of a beam splitter the light beam of a laser is converted into two part beams crossing on or in the measured object and with the help of an optical receiver the spectral maximum of the intensity modulation of the reflected light is measured. A Koster prism is used as a beam splitter such that the part beams formed intersect at the desired angle on or in the measured object.
    Type: Grant
    Filed: October 14, 1997
    Date of Patent: May 16, 2000
    Assignee: LAP GmbH Laser Applikationen
    Inventor: Peter Drewling
  • Patent number: 6058128
    Abstract: Apparatus is provided for an improved stabilized laser source comprising a laser source having a light beam output and an electrical input. An optical waveguide, such as an optical fiber, having an input end is optically coupled to the laser source to receive the light beam. A reflector in the optical fiber, such as fiber grating, reflects a portion of the light beam output back into the laser source. The reflector is provided at a distance from the laser source permitting the laser source to switch between states of coherence and coherence collapse of operation. The electrical input of a drive signal for the laser source includes a modulated signal with variations in amplitude to the electrical input to control the variation in switching between the states of coherence and coherence collapse of the laser source so that continuous laser operation remains kink-free.
    Type: Grant
    Filed: March 25, 1996
    Date of Patent: May 2, 2000
    Assignee: SDL, Inc.
    Inventor: Brian F. Ventrudo
  • Patent number: 6034977
    Abstract: A method of controlling the thermal optical path difference (OPD) in a lasing medium in a solid state laser during pumping of a lasing medium 10 including a pair of side faces 12 for receiving radiation during pumping and a pair of edge faces 16, comprises the steps of determining a temperature difference, .DELTA.T.sub.min, between the side faces and the edge faces that corresponds with approximately a minimum, OPD.sub.min, in the OPD, and maintaining about .DELTA.T.sub.min during pumping of the lasing medium, such that the OPD is maintained at approximately OPD.sub.min. The temperature difference is maintained by controlling heat transfer at the edge faces of the lasing medium. The temperature difference between the edge faces and the side faces can be actively controlled such that the method can be automated.
    Type: Grant
    Filed: February 17, 1998
    Date of Patent: March 7, 2000
    Assignee: TRW Inc.
    Inventor: Randall J. St. Pierre
  • Patent number: 6021145
    Abstract: A laser diode array unit for use in laser beam scanning optical apparatus and the like. The laser diode array has plural light emitting sources to be drivingly controlled independently of each other. The laser diode array is so disposed as to permit laser beams emitted from the light emitting sources to be incident to a collimator lens. On an optical axis between the laser diode array and the collimator lens is disposed a beam splitter for splitting the laser beams emitted from the light emitting sources into image light and monitor light. A magnifier lens and a photoreceptor element are arranged on the optical axis so as to allow incidence of monitor light oriented to advance in a direction perpendicular to the direction of advance of image light.
    Type: Grant
    Filed: September 17, 1997
    Date of Patent: February 1, 2000
    Assignee: Minolta Co., Ltd.
    Inventors: Toshio Naiki, Akiyoshi Hamada
  • Patent number: 6014397
    Abstract: A coated ceramic insulator in a laser chamber that is exposed to a gaseous environment where impurities in the ceramic insulator are prevented from detrimentally contaminating the laser chamber by a high-purity insulating coating. The insulating coating prevents chemical interactions between the ceramic insulator and the gaseous environment. In particular, the coating prevents contamination, by impurities in the ceramic insulator, of the lasing gas.
    Type: Grant
    Filed: June 2, 1998
    Date of Patent: January 11, 2000
    Assignee: Cymer, Inc.
    Inventors: Toshihiko Ishihara, Richard G. Morton
  • Patent number: 5999549
    Abstract: A method and apparatus are provided for laser safety. A fault detector detects laser fault conditions and generates a laser fault control signal. A laser fault counter is coupled to the fault detector for counting laser fault conditions and for generating a disable laser control signal responsive to a predetermined fault count. A reset timer is coupled to the laser fault counter for identifying a predetermined reset time period responsive to the laser fault control signal and applying a reset signal to the laser fault counter. Features of laser safety method and apparatus of the invention are that the laser fault counter is reset if a second laser fault condition is not detected within the predetermined reset time period after the laser is turned on. The disable laser control signal is not generated when a safe laser optical power condition occurs between two laser fault conditions.
    Type: Grant
    Filed: February 9, 1998
    Date of Patent: December 7, 1999
    Assignee: International Business Machines Corporation
    Inventors: Ladd W. Freitag, David Warren Siljenberg, Raymond Jonathan Thatcher
  • Patent number: 5991068
    Abstract: In a gain-controlled erbium-doped optical amplifier, gain control is achieved by clamping the gain of a laser cavity to be equal to the overall cavity loss and by fixing the resonant wavelength of the amplifier to be at a first wavelength. When an optical signal to be amplified having a second wavelength different from the first wavelength passes through the amplifier the gain experienced by the signal depends entirely on the gain of the cavity, and not on the intensity of the signal. If the first wavelength is arranged to be at the peak of the sum of the absorption and emission cross sections of erbium, the amplifier exhibits minimum sensitivity to ambient changes in temperature.
    Type: Grant
    Filed: October 21, 1996
    Date of Patent: November 23, 1999
    Assignee: British Telecommunications public limited company
    Inventors: Jennifer Massicott, Richard Wyatt
  • Patent number: 5986759
    Abstract: Method and apparatus for realizing unusually sensitive and stable interferometric measurement capabilities. The apparatus comprises an optical interferometer with at least two optical outputs, the ratio of whose intensities can vary with a tuning parameter; and at least one detector, each of which is optically connected to the interferometer, and producing in aggregate at least two linearly-independent signals that depend on the light intensity and the tuning parameter, which are combined to produce a first measurement whose sensitivity to light intensity changes is substantially smaller than that of either of the two linearly-independent signals, and a second measurement whose sensitivity to the tuning parameter is substantially smaller than that of either of the two linearly-independent signals.
    Type: Grant
    Filed: July 13, 1998
    Date of Patent: November 16, 1999
    Assignee: International Business Machines Corporation
    Inventors: Donald Michael DeCain, Philip C. D. Hobbs, Keith Randal Pope
  • Patent number: 5982789
    Abstract: A diode pumped doubling system employs a pump diode, a crystal and doubler in a laser cavity with the diode and is operated in a pulsed or low duty cycle pumping regimen, while the cavity length is sufficiently short to stabilize the transient responses to pulsed diode operation and produce stable and known or controlled energy output under the non-CW pumping regimen. The construction allows stable output to be maintained with much looser temperature control, and to be achieved during the initial turn-on interval of the laser diode. In a preferred embodiment, the device employs a doubler which is clamped across its non-critical axis, and is operated with a control system which creates isotherms in the active mode volume.
    Type: Grant
    Filed: May 30, 1997
    Date of Patent: November 9, 1999
    Assignee: Light Solutions Corporation
    Inventors: Larry R. Marshall, Wayne E. Kelsoe, David M. Buzawa
  • Patent number: 5982787
    Abstract: A free electron laser amplifier provides a scalloping annular electron beam that interacts with the axial electric field of a TM.sub.0n mode. A waveguide defines an axial centerline and, a solenoid arranged about the waveguide produces an axial constant magnetic field within the waveguide. An electron beam source outputs a annular electron beam that interacts with the axial magnetic field to have an equilibrium radius and a ripple radius component having a variable radius with a ripple period along the axial centerline. An rf source outputs an axial electric field that propagates within the waveguide coaxial with the electron beam and has a radial mode that interacts at the electron beam at the equilibrium radius component of the electron beam.
    Type: Grant
    Filed: April 21, 1998
    Date of Patent: November 9, 1999
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventor: Bruce E. Carlsten
  • Patent number: 5974066
    Abstract: The present invention provides a low cost, efficient vertical cavity surface emitting laser package (300) and manufacturing method, the package having a head assembly having at least three leads, a vertical cavity surface emitting laser die bonded to a top surface of the head assembly, for generating a beam of light, and a photodiode, die bonded to the top surface of the head assembly proximate to the vertical cavity surface emitting laser for receiving at least a portion of the beam of light, and generating feedback for adjusting an electrical input current to the vertical cavity surface emitting laser based on a received optical power of the portion of the beam of light received. The vertical cavity surface emitting laser and the photodiode are injection molded in a predetermined shape with a recessed area for placement of a partially reflective holographic optical element/reflector.
    Type: Grant
    Filed: May 9, 1997
    Date of Patent: October 26, 1999
    Assignee: Motorola, Inc.
    Inventors: Sean Wu, Chao-pin Yeh, Karl Wyatt, Jang-Hun (James) Yeh, James Morikuni
  • Patent number: 5970076
    Abstract: A wavelength tunable semiconductor laser light source, which has an external resonator semiconductor laser source unit; an optical filter for selecting an output beam of the external resonator semiconductor laser source unit in a single mode; a drive unit for changing wavelength of a transmitted beam or of a reflected beam, from the optical filter; and a control unit for controlling the drive unit; a first beam splitting device for receiving the output beam of the external resonator semiconductor laser source unit as one of incident beams and for outputting it into two branches; an etalon for receiving one of output beams from the first beam splitting device; a measuring unit for etalon transmittance, for measuring a transmittance of the etalon to transmit it to the control unit; and a wavemeter for specifying a wavelength of the output beam of the semiconductor laser source unit with an accuracy in a free spectral range of the etalon, on the basis of the output beam of the semiconductor laser source unit or
    Type: Grant
    Filed: March 23, 1998
    Date of Patent: October 19, 1999
    Assignee: Ando Electric Co., Ltd.
    Inventor: Madoka Hamada
  • Patent number: 5956357
    Abstract: A laser diode driving apparatus produces a simple write signal having an attenuated waveform to drive the laser diode. A laser diode emits laser light on an optical disk according to a write signal to record data thereon. A laser diode driver outputs a predetermined, plurality of write power values each being different from each other. A write control signal generator calculates widths of a kick pulse and a brake pulse corresponding to the pulse width of the received NRZI signal, and generates write control signals in a predetermined order for controlling write power values corresponding to the calculated widths of the kick pulse and the brake pulse. A write signal generator supplies a write signal to the laser diode using a plurality of the write power values according to the write control signals generated by the write control signal generator. Accordingly, a write domain can be made to be close to a distinct oval.
    Type: Grant
    Filed: August 29, 1997
    Date of Patent: September 21, 1999
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Seong-Sin Joo
  • Patent number: 5956356
    Abstract: The invention is a circuit for monitoring the wavelength of a laser device such as a semiconductor laser. A piezoelectric resonator is positioned in the path of the light beam so as to form a Fabry-Perot cavity. The changes in the reflectivity of the cavity are detected as the resonator is driven by an oscillator circuit, and an error signal is produced in response thereto when the wavelength of the laser device strays from a desired value.
    Type: Grant
    Filed: December 8, 1997
    Date of Patent: September 21, 1999
    Assignee: Lucent Technologies Inc.
    Inventors: Ernest Eisenhardt Bergmann, Carl Edward Gaebe
  • Patent number: 5953108
    Abstract: A rotating laser beam projector includes a power controller having a micro controller coupled to a laser power circuit which determines whether the laser beam emitted by the projector is rotating or stationary. When the laser beam is rotating, the laser power circuit delivers a first level of continuance power to the laser. When the laser beam is stationary, the laser power circuit delivers a second level of continuance power to the laser which is less than the first level of power. The micro controller communicates messages from the laser beam projector to a remotely positioned sensor assembly by rotating the laser beam at a first speed when no message is to be communicated and rotating the laser beam at a second speed, different from the first speed, when a message is to be communicated. The laser beam projector includes a bridge for delivering electrical power to a pendulum-supported device from a stationary source.
    Type: Grant
    Filed: October 31, 1997
    Date of Patent: September 14, 1999
    Assignee: Laser Alignment, Inc.
    Inventors: David M. Falb, Brian G. Zomberg, Bruce A. Boersma
  • Patent number: 5953354
    Abstract: A laser resonator includes a laser medium having opposite end faces inclined at Brewster's angle and disposed in optical alignment between spaced-apart and tilted first and second optical elements. A method for adjusting the optical alignment includes pumping the laser medium to produce a laser beam, and adjusting separation spacing between the two optical elements. Tilt of at least one of the optical elements is adjusted in response to any observed change in beam cross-sectional size. In an additional embodiment, the laser medium is initially positioned at about equal spacings between the first and second elements. Position of the laser medium is then adjusted, at a constant value of the separation spacing, to within a position range selected for a specific value of a ratio of intracavity peak power of circulation of the laser beam and a critical power for self-focusing to effect discrimination of mode-locked operation over continuous wave operation.
    Type: Grant
    Filed: February 3, 1998
    Date of Patent: September 14, 1999
    Assignee: General Electric Co.
    Inventors: Phillip Randall Staver, William Taylor Lotshaw
  • Patent number: 5946332
    Abstract: A connection monitoring system is provided for monitoring a connection between separated oscillator and power units not only in an initial time period just after the connector has been connected to the interface but also in a time period when the laser is in serve for allowing a long life time of the laser by preventing the laser oscillator unit from an excess large load even if a connector is incompletely connected to an interface of the electric device or if a connector pin is incompletely in contact with the interface. A thermal switch recognition system is further provided for recognizing excess temperature increase of the laser tube which can ascertain which thermal switch has been opened for allowing a long life-time of the laser tube by recognizing a position where an excess temperature increase appears.
    Type: Grant
    Filed: September 25, 1997
    Date of Patent: August 31, 1999
    Assignee: NEC Corporation
    Inventor: Tsutomu Terao
  • Patent number: 5943352
    Abstract: A stable switched multifrequency source is described. The stable switched multifrequency source includes a narrowband reflective optical filter bank. This bank includes a plurality of narrowband reflective optical filter devices. In one embodiment, the stability and precision of the reflectivity of the narrowband reflective optical filter devices is further enhanced through regulation via temperature and/or bias current based on a comparison of the output wavelength and a precise stable wavelength reference. The stable switched multifrequency source also includes an optical switch that is coupled to each of the narrowband reflective optical filter devices.
    Type: Grant
    Filed: March 25, 1997
    Date of Patent: August 24, 1999
    Assignee: MCI Communication Corporation
    Inventor: John Fee
  • Patent number: 5936994
    Abstract: A complex coupled (gain coupled or loss coupled) distributed feedback (DFB) semiconductor laser, having two sections axially distinct along a cavity length direction, and two excitation means for independent pumping of corresponding sections of the laser in a master and slave type of pumping control, is provided. An extended continuous wavelength tuning range of the laser is obtained by selectively activating a left Bragg mode or a right Bragg mode across the stop band of the laser as a dominant lasing mode by the master and slave type of current injection control into different sections of the laser to alternate gain coupling and loss coupling mechanisms of laser operation, and further tuning a wavelength around the activated Bragg mode. Methods of operating the laser, enhancing a tuning range, and fabricating thereof are provided.
    Type: Grant
    Filed: September 18, 1997
    Date of Patent: August 10, 1999
    Assignee: Northern Telecom Limited
    Inventors: Jin Hong, Hyung B. Kim, Toshi Makino
  • Patent number: 5914972
    Abstract: A thermal compensator for stabilization of the operation of a waveguide DBR laser against changes in its operational parameters due to operational temperature changes so that thermally induced longitudinal mode hopping in the laser is suppressed and, in addition, the desired operational wavelength may be stabilized.
    Type: Grant
    Filed: March 24, 1997
    Date of Patent: June 22, 1999
    Assignee: SDL, Inc.
    Inventors: Sabeur Siala, Steven Sanders, Mehrdad Ziari
  • Patent number: 5907569
    Abstract: A selected positive coefficient resistor is connected in parallel across a laser, Light Emitting Diode (LED) or amplifier LED (ALED) to adjust the bias current, respectively, to the laser, LED or ALED as a function of temperature so as to maintain a more regulated optical power output therefrom.
    Type: Grant
    Filed: May 28, 1997
    Date of Patent: May 25, 1999
    Assignee: Lucent Technologies Inc.
    Inventors: Bernard Glance, Kang-Yih Liou
  • Patent number: 5907402
    Abstract: A multioscillator ring laser gyro having a Faraday Cell with an optical wedge in one of its branches. Variations in the MCDL of the optical wedge with temperature are reduced to substantially zero. The internally specularly reflected and backscattered beams from said primary beam have path lengths such that the internally double-bounced reflected and scattered beams of each mode have path lengths wherein the differences between the mode directions are adjusted in a particular manner to reduce cyclic variations with temperature in MCDL substantially to zero.
    Type: Grant
    Filed: February 12, 1990
    Date of Patent: May 25, 1999
    Inventor: Graham J. Martin
  • Patent number: 5905749
    Abstract: In a resonating-type solid-state laser oscillator including birefringent a solid-state element containing a laser active medium and providing a plurality of thermal lenses during excitation and reflecting mirrors arranged oppositely to each other on both sides of the solid-state element so that their optical axes are coincident to each other, a prescribed relationship is given among the refractive index and length of the solid-state element, the radii of curvature of the reflection mirrors, the distances between the reflecting mirrors and the solid-state element and the difference between 1/f of the plurality of thermal lenses by owing to birefringence of the solid-state element, so that oscillation areas due to the plurality of thermal lenses are separated from each other.
    Type: Grant
    Filed: September 26, 1996
    Date of Patent: May 18, 1999
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Kuniaki Iwashiro, Kenji Kumamoto
  • Patent number: 5903584
    Abstract: A surface-mounted flat package for a laser diode has the laser diode and light sensor diode mounted on top of a printed wiring insulating substrate. These diodes are connected to electrodes at the corners of the package. These electrodes may be fed through plated through via holes to form bottom electrodes. These via holes may be located at the four corners of the substrate or inside the edges of the package.For mass production, a matrix of laser diode and sensor diode assemblies are mounted on a common substrate. The substrate is sawed orthogonally through or outside the via holes to yield a large number of dice.
    Type: Grant
    Filed: January 5, 1998
    Date of Patent: May 11, 1999
    Assignee: Youngtek Electronics
    Inventor: Wu Jiahn-Chang
  • Patent number: 5870422
    Abstract: A gain generator 10 for use in high-energy flowing gas lasers such as COIL devices comprises a chemical reactant mixing nozzle 12 disposed in a gain medium 16. The nozzle includes a plurality of blades 22 formed of a plastic material resistant to chemical attack at the operating temperature of the gain medium and non-catalytic to O.sub.2 (.sup.1 .DELTA.). A preferred material is polyetherimide. The gain medium includes octagonal shaped openings 50 for the optical mode of the laser beam.
    Type: Grant
    Filed: July 9, 1997
    Date of Patent: February 9, 1999
    Assignee: TRW Inc.
    Inventors: Caesar C. Florentino, Raj K. Gupta, Jeffrey S. Hartlove, Charles W. Clendening, Jr., James L. Reeve
  • Patent number: 5862165
    Abstract: A variable wavelength light source is provided with a laser of which the oscillating state can be changed over between two oscillating states accompanied by a change of an oscillation wavelength, and an optical selection element for selecting an output light in one of the two oscillating states of the laser. The optical selection element is capable of changing over which of the output lights in the two oscillating states of the laser is to be selected. Also, by using a laser in which the oscillation wavelength in the respective oscillating states can be changed, the wavelength variation ranges in the both oscillating states can be used.
    Type: Grant
    Filed: August 29, 1996
    Date of Patent: January 19, 1999
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yuichi Handa, Masao Majima, Jun Nitta
  • Patent number: 5854804
    Abstract: A method and an apparatus for synchronizing a mode locked laser with a device under test. The present invention provides a stroboscopic technique that synchronizes the free running laser pulses of a mode locked laser to a DUT enabling the optical testing of integrated circuits to be performed and waveform measurements to be acquired from a DUT at random operating frequencies. In one embodiment, a laser synchronizing apparatus is configured to be used to test a device under test . The laser synchronizing apparatus includes a mode locked laser generating repeating laser pulses having a first period. A test pattern operating in M clocks when executed on the device under test is constructed. M is an integer and each one of the M clocks has a second period. A time per test pattern is computed such that the time per test pattern provides a sufficient amount of time to execute the constructed test pattern operating in the M clocks.
    Type: Grant
    Filed: December 13, 1996
    Date of Patent: December 29, 1998
    Assignee: Intel Corporation
    Inventors: Paul Winer, Mario J. Paniccia
  • Patent number: 5828689
    Abstract: A control system for an etalon arrangement 4, in an optical transmission system involves applying a dither to a laser 1 upstream of the arrangement, monitoring the output of the arrangement, and using a control means 3 to lock the laser frequency to the etalon arrangement response, or vice versa. The control means operates on the basis of a ratio of derivatives of the monitored output with respect to wavelength, to enable locking to a point on the response curve, independent of power variations.
    Type: Grant
    Filed: April 30, 1997
    Date of Patent: October 27, 1998
    Assignee: Northern Telecom Limited
    Inventor: Richard Edward Epworth
  • Patent number: 5825793
    Abstract: A laser having, a resonator structure including a wavelength variable laser crystal containing a fluoride and an optical part for controlling the wavelength of radiation from the laser crystal, a device to excite the laser crystal, a device for detect reflected light from the optical part as a sample beam, and a device to stabilize the output of a laser beam from the resonator structure based on the sample beam.
    Type: Grant
    Filed: May 30, 1996
    Date of Patent: October 20, 1998
    Assignee: Hitachi Metals, Ltd.
    Inventors: Tsuyoshi Miyai, Satoshi Makio, Yasunori Furukawa, Masayoshi Sato
  • Patent number: 5815494
    Abstract: Laser annealing is performed by irradiating, while scanning, a semiconductor thin-film with laser light. The laser light that is linear on the irradiation surface is moved in its line-width direction and applied non-continuously. The laser light has, in its line-width direction, an energy density profile that assumes a step-like form in which the energy density varies in a step-like manner. In particular, the scanning pitch D and the step widths L.sub.n are so set as to satisfy a relationship L.sub.n .gtoreq.D.
    Type: Grant
    Filed: February 12, 1997
    Date of Patent: September 29, 1998
    Assignee: Semiconductor Energy Laboratory Co., Ltd.
    Inventors: Shunpei Yamazaki, Koichiro Tanaka, Naoto Kusumoto
  • Patent number: 5809050
    Abstract: An integrated laser-based light source that generates an output light beam having a controlled intensity. The light source comprises a package, a laser, a light sensor, and a beam splitter. The beam splitter is mounted in the package, together with the laser and the light sensor. The laser has one and only one light-emitting face from which it radiates a light beam as a radiated light beam. The light sensor generates an electrical signal representing the intensity of light energy falling on it. The beam splitter divides the radiated light beam into a fraction and a remainder, the remainder being the output light beam. The beam splitter operates by diffraction, scattering, or transmission to direct the fraction of the radiated light beam towards the light sensor.
    Type: Grant
    Filed: January 25, 1996
    Date of Patent: September 15, 1998
    Assignee: Hewlett-Packard Company
    Inventors: Richard R. Baldwin, Scott W. Corzine, William D. Holland, Leif Eric Larson, David M. Sears, Michael R.T. Tan, Shih-Yuan Wang, Albert T. Yuen, Tao Zhang
  • Patent number: 5784396
    Abstract: There is disclosed a vertical cavity laser diode (VCSEL) assembly with an integral set of detectors for the purpose of individually monitoring and adjusting the output power of each laser diode. A plate which has a plurality of light detectors and a plurality of apertures is bonded to a laser light source which has a plurality of VCSELs. Each aperture of the plate is aligned with a corresponding VCSEL and each light detector is electrically connected to a corresponding VCSEL.
    Type: Grant
    Filed: September 17, 1996
    Date of Patent: July 21, 1998
    Assignee: Xerox Corporation
    Inventor: Jean-Michel Guerin
  • Patent number: 5774486
    Abstract: A power monitoring system including a vertical cavity surface emitting laser generating an emission. A beam splitter optically positioned to receive the emission and split the emission into a first portion and a second portion. A monitor optically positioned to receive the first portion of the emission. An output of the monitor is used to control emissions of the vertical cavity surface emitting lasers.
    Type: Grant
    Filed: April 30, 1996
    Date of Patent: June 30, 1998
    Assignee: Motorola, Inc.
    Inventors: Wenbin Jiang, Michael S. Lebby
  • Patent number: 5774485
    Abstract: A wavelength-tunable laser device has an active part comprising an active laser region for generating a laser emission with a predetermined emission wavelength, and a tuning part comprising a tuning region allocated to the active laser region and capable of tuning the emission wavelength of the laser light emitted by the active region. The active part is charged with a chronologically variable modulation current that controls the intensity of the emitted laser emission, and the tuning part is charged with an electrical tuning current for controlling the emission wavelength of the emitted laser light. The active part controls the intensity of the emitted laser light and the tuning part is charged with an electrical tuning current for controlling the emission wavelength of the emitted laser light. The tuning current that is supplied to the tuning part and controls the emission wavelength of the emitted laser light is directly derived from the chronologically variable modulation current.
    Type: Grant
    Filed: September 17, 1996
    Date of Patent: June 30, 1998
    Assignee: Siemens Aktiengesellschaft
    Inventor: Karl-Ulrich Stein