Feedback Circuitry Patents (Class 372/29.011)
  • Publication number: 20100246613
    Abstract: A semiconductor laser is provided capable of generating very narrow laser beams and having stable characteristics, a method for generating the laser beams and a method for reducing a spectral line-width of the laser beams. The semiconductor laser includes a semiconductor active layer, a photonic crystal optical waveguide forming a periodic structure of two-dimensional refractive index within a plane perpendicular to a semiconductor laminate direction directly or indirectly connected to the semiconductor active layer; and an optical cavity that contains the semiconductor active layer and the photonic crystal optical waveguide and oscillates light that is generated from the semiconductor active layer and is guided through the photonic crystal optical waveguide as laser.
    Type: Application
    Filed: January 19, 2010
    Publication date: September 30, 2010
    Inventor: Hideaki Hasegawa
  • Publication number: 20100246614
    Abstract: There is provided a wavelength variable light source system capable of changing wavelength and intensity of output signal light and of improving preset accuracy and stability of the wavelength and strength of the output signal light. The system determines the both or either one of a target value for controlling wavelength and a target value for controlling intensity of output signal light of a wavelength variable light source by correlating a combination of the target wavelength and the target light output intensity specified from a higher-level device and controls operation states of the wavelength variable light source so that output values of monitoring circuit s for monitoring the operation state of the wavelength variable light source converge to the target values.
    Type: Application
    Filed: March 26, 2010
    Publication date: September 30, 2010
    Inventors: Hiroyuki Koshi, Koji Horikawa
  • Patent number: 7801189
    Abstract: Examples and implementations of photonic devices and techniques based on whispering gallery mode resonators formed of electro-optic materials to effectuate cross modulation between whispering gallery modes of different polarizations in the resonators.
    Type: Grant
    Filed: November 13, 2008
    Date of Patent: September 21, 2010
    Assignee: OEWaves, Inc.
    Inventors: Lutfollah Maleki, Andrey B. Matsko, Anatoliy Savchenkov, Vladimir Ilchenko
  • Patent number: 7782915
    Abstract: The present invention is to provide alight emitting module that improves the positional precision of a semiconductor laser diode. A light emitting module of the present invention is configured with a semiconductor laser diode having a facet which inputs, or outputs light; an integrated circuit which is electrically connected to the semiconductor laser diode; and a package which mounts the semiconductor laser diode and the integrated circuit therein. The semiconductor laser diode is mounted on the integrated circuit, and the integrated circuit has a marker. The marker is utilized in determining a position of the semiconductor laser diode with respect to the integrated circuit, and further in determining a position of the semiconductor laser diode with respect to the package.
    Type: Grant
    Filed: August 22, 2006
    Date of Patent: August 24, 2010
    Assignee: Sumitomo Electric Industries Ltd.
    Inventor: Akihiro Moto
  • Patent number: 7777940
    Abstract: Methods and systems for optical chirped pulse amplification and phase dispersion, the system including an active dispersion controller for receiving an input optical pulse from a modelocked laser and controlling a third and fourth order dispersion property of the input optical pulse to produce an optical output pulses, a stretching re-circulating loop for stretching the optical output pulses in time, an optical amplifier for amplifying the stretched optical output pulses, a compressing re-circulating loop for compressing the amplified stretched optical output pulse to produce a compressed optical output pulse, and a feedback loop for feeding a feedback optical signal to the active dispersion controller.
    Type: Grant
    Filed: February 8, 2008
    Date of Patent: August 17, 2010
    Assignee: University of Central Florida Research Foundation, Inc.
    Inventors: Peter J. Delfyett, Scott Rozzo
  • Patent number: 7773652
    Abstract: In a gain-coupled distributed feedback semiconductor laser, a coating of a low reflectivity is provided on a front facet from which laser light is emitted and a coating of a high reflectivity is provided on a rear facet, thus forming asymmetric coatings. The semiconductor laser has a structure in which an absorption diffraction grating is located along an optical waveguide, and the diffraction grating includes a phase shift region.
    Type: Grant
    Filed: June 27, 2006
    Date of Patent: August 10, 2010
    Assignee: Mitsubishi Electric Corporation
    Inventors: Kazuhisa Takagi, Keisuke Matsumoto
  • Publication number: 20100195682
    Abstract: Jitter and waveform are improved by reducing the wavelength spectrum width of a laser beam pulse. In a laser pulse generating apparatus according to the present invention, a semiconductor laser device, a polarization maintaining optical fiber, an optical reflection filter having bandpass characteristics using an FBG whose passband can be changed by changing a tension, and an optical isolator are connected via an optical fiber. A driving circuit drives the semiconductor laser device to generate a pulse. The optical reflection filter performs filtering by transmitting a specific component of the wavelength spectrum of the pulse, reflects a portion of the optical power, and outputs the remaining optical power except the reflected portion to the outside via the optical isolator. The reflected pulse is fed back to the semiconductor laser device to thereby reduce the wavelength spectrum width of the laser beam, and improve the jitter and waveform.
    Type: Application
    Filed: June 16, 2008
    Publication date: August 5, 2010
    Inventor: Koji Nonaka
  • Patent number: 7760779
    Abstract: The laser drive circuit of the present invention includes a first drive circuit 105 receiving an input of a current from a variable current source 103 and a first pulse control signal 101 and outputting a first drive current in synchronism with the first pulse control signal 101; a pulse output circuit 107 outputting a pulse signal in response to a falling edge of the first pulse control signal 101; and a second drive circuit 106 receiving an input of a current from a variable current source 104 and a second pulse control signal 102, generating a second drive current in synchronism with the second pulse control signal 102, and outputting a decreased current value of the second drive current at least in synchronism with the pulse signal. According to this configuration, the falling time of the pulse can be shortened regardless of the relationship between the voltage of a laser connecting terminal and the power source voltage of a drive circuit or a ground voltage.
    Type: Grant
    Filed: April 5, 2007
    Date of Patent: July 20, 2010
    Assignee: Panasonic Corporation
    Inventor: Haruhiko Mizuno
  • Publication number: 20100158055
    Abstract: A method of monitoring the output power of a laser diode in a barcode reader. The method includes sampling a threshold monitoring-current that is related the driving-current passing through the laser diode during a first time period when this current is at the lasing threshold of the laser diode. The method includes generating a threshold-compensated monitoring-current by subtracting the threshold monitoring-current from the above-threshold monitoring-current. The method includes monitoring the output power of the laser diode in the barcode reader at least partially based on the threshold-compensated monitoring-current.
    Type: Application
    Filed: December 18, 2008
    Publication date: June 24, 2010
    Inventor: James Giebel
  • Publication number: 20100150189
    Abstract: A laser control method includes the steps of: using a laser control circuit which includes a constant current circuit that maintains a constant current flowing through a semiconductor laser element, and which includes an adder and a multiplier connected to a stage preceding the constant current circuit, and using detection means for calibration for detecting an applied laser output; calculating, on the basis of a detection signal output from the detection means, a reference bias value and a reference gain value for obtaining a specified laser output with respect to a specified input to the multiplier; inputting the reference bias value and the reference gain value to the adder and the multiplier, respectively; and controlling the applied laser output from the semiconductor laser element by performing calibration.
    Type: Application
    Filed: November 25, 2009
    Publication date: June 17, 2010
    Inventors: Kunio Nakayama, Koji Ishiwata, Cheonseok Park
  • Publication number: 20100135346
    Abstract: The present invention provides a system and method for creating a coherent optical comb comprising a plurality of lasers, each laser providing an optical output channel; means for combining each optical channel output; a modulator for modulating the combined optical channel outputs, to provide a modulated signal; means for feeding back said modulated signal to said plurality of lasers, such that each laser output channel is phase and/or frequency locked with respect to at least one other of said plurality of lasers. A discrete optical comb is obtained without the need for excessively high power laser outputs and only employs a single (optional) wavelength locker for all channels.
    Type: Application
    Filed: October 6, 2009
    Publication date: June 3, 2010
    Applicant: University College Cork
    Inventors: Frank Peters, Andrew Ellis
  • Patent number: 7725043
    Abstract: A laser transmitter with a feedback control loop for minimizing noise. The novel laser transmitter includes a laser, an external reflector adapted to form an extended cavity to the laser, and a feedback control loop adapted to detect noise in the laser and in accordance therewith, adjust the optical phase of the extended cavity such that the noise is at a desired level. The optical phase of the extended cavity is adjusted by adjusting an operating parameter of the laser, such as its bias current. In an illustrative embodiment, the feedback control loop is adapted to compute the rate of change of the noise with respect to bias current and in accordance therewith, adjust the bias current of the laser such that relative intensity noise and interferometric intermodulation distortion are simultaneously minimized.
    Type: Grant
    Filed: October 7, 2004
    Date of Patent: May 25, 2010
    Assignee: Raytheon Company
    Inventors: Willie W. Ng, David L. Persechini, Robert H. Buckley
  • Patent number: 7711018
    Abstract: The luminance of a laser diode is a function of laser diode drive current. The luminance is also a function of other factors, such as age and temperature. A laser projection device includes laser diodes to generate light in response to a commanded luminance, and also includes photodiodes to provide a measured luminance. The commanded luminance and measured luminance are compared, and drive currents for the laser diodes are adjusted to compensate for changes in laser diode characteristics.
    Type: Grant
    Filed: December 21, 2007
    Date of Patent: May 4, 2010
    Assignee: Microvision, Inc.
    Inventors: Mark Champion, Heng Huang
  • Patent number: 7711021
    Abstract: The present invention provides a laser diode driving circuit able to reduce the degradation of the optical output from the laser diode even when the characteristic of the laser diode widely scatters. The circuit provides a filter circuit connected in parallel to the laser diode that compensates the frequency dependence of the laser diode. In the invention, the frequency characteristic of this filter circuit may be varied depending on the scattering in the frequency response of the laser diode, or on the temperature characteristic of the diode.
    Type: Grant
    Filed: May 31, 2007
    Date of Patent: May 4, 2010
    Assignee: Sumitomo Electric Industries Ltd.
    Inventor: Naoki Nishiyama
  • Publication number: 20100091806
    Abstract: A method for improving spectral, spatial, and temporal stability of semiconductor lasers and their beam profile uniformity based on statistical average of plural transient or unsteady state longitudinal and lateral modes that are continuously perturbed. A laser module implementing the method comprises a semiconductor laser, a drive circuit generating RF-modulated drive current, and an automatic power control loop for producing stable, low noise and uniform or nearly uniform illumination field along one or two dimensions.
    Type: Application
    Filed: October 10, 2008
    Publication date: April 15, 2010
    Applicant: Pavilion Integration Corporation
    Inventors: Ningyi Luo, Sheng-Bai Zhu, Hui Fan, Jindong Li
  • Patent number: 7697579
    Abstract: Methods and devices for a coupled optoelectronic oscillator having optical frequency stabilization. The coupled optoelectronic oscillator includes a harmonically mode-locked laser cavity having a Mach-Zehnder modulator for mode-locking and an intracavity Fabry-Perot etalon to allow only one single supermode to lase, a stabilization loop coupled with the Fabry-Perot etalon to detect changes in the laser cavity optical frequency and generate an error signal to compensate for the frequency change to stabilize the mode-locking of the laser frequency stabilization, and an electrical loop between the laser cavity and the stabilization loop for driving the Mach-Zehnder modulator with the coupled optoelectronic oscillator signal.
    Type: Grant
    Filed: December 12, 2007
    Date of Patent: April 13, 2010
    Assignee: University of Central Florida Research Foundation, Inc.
    Inventors: Peter J. Delfyett, Franklyn Quinlan, Sangyoun Gee, Sarper Ozharar
  • Patent number: 7697580
    Abstract: A power monitoring and correction to a desired power level of a laser or group of lasers utilizes two photodetectors which are employed to accurately determine the amount of output power from the front end or “customer” end of a laser or a plurality of such lasers. During power detection, which may be accomplished intermittently or continuously, the laser is modulated with a tone of low frequency modulation. One photodetector at the rear of the laser is employed to detect the DC value of the frequency tone, i.e., a value or number representative of the AC peak-to-peak swing, amplitude or modulation depth of the tone. Also, the rear photodetector may be employed to determine the optical modulation index (OMI). In either case, these values may be employed in a closed loop feedback system to adjust or otherwise calibrate the value of the low tone frequency relative to the total desired bias current applied to the laser.
    Type: Grant
    Filed: October 8, 2004
    Date of Patent: April 13, 2010
    Assignee: Infinera Corporation
    Inventors: Robert W. Smith, Alan C. Nilsson
  • Patent number: 7692502
    Abstract: The invention relates to a method for controlling an oscillatory system with the aid of at least one measured variable by the detection of at least one oscillation component (Sx(t)) over time (t) in the form of at least one measured variable. According to said method a control variable (?u) for controlling the oscillatory system is determined from the sum of the weighted differences of the delayed oscillation component, which has been delayed at least twice by different delay times (?1>O, ?2>0) if there is one measured variable and the respective non-delayed oscillation component and if there are several measured variables the sum of the weighted differences of the delayed oscillation components (Si(t??i)), which have been respectively delayed at least once by a specific delay time (?i>0) and their respective non-delayed oscillation components (Si(t)) according to the relationship ?u=a1S1(t) b1S1(t??1)+ . . . +anSn(t)?bnSn(t??n), wherein a1, . . . , an and b1, . . .
    Type: Grant
    Filed: June 8, 2005
    Date of Patent: April 6, 2010
    Assignee: Georg-August-Universitat Gottingen
    Inventors: Ulrich Parlitz, Alexander Ahlborn
  • Publication number: 20100054288
    Abstract: The present invention relates to a method and device for reducing the phase noise of a laser signal from a laser source. This device comprises a first current generator for supplying a driving current to the laser source in view of producing the laser signal. A phase noise detector is responsive to the laser wavelength for generating a phase error signal and a second current generator is responsive to the phase error signal for generating a compensation current added to the driving current supplied to the laser source for generating a phase-adjusted laser signal. The device therefore defines a phase stabilization loop formed by the phase noise detector and the second current generator, for reducing the phase noise of the laser signal.
    Type: Application
    Filed: October 12, 2006
    Publication date: March 4, 2010
    Applicant: Sensilaser Technologies Inc.
    Inventor: Qing He
  • Patent number: 7672345
    Abstract: A drive signal for driving a semiconductor laser is generated on the basis of an image signal inputted in synchronism with a pixel clock. A bias signal to the semiconductor laser is generated at a timing earlier than the drive signal by a predetermined time. The bias signal is disabled in synchronism with the leading edge of the drive signal.
    Type: Grant
    Filed: January 20, 2009
    Date of Patent: March 2, 2010
    Assignee: Canon Kabushiki Kaisha
    Inventor: Tsuyoshi Moriyama
  • Patent number: 7656037
    Abstract: An integrated circuit arrangement is disclosed. In one embodiment, the integrated circuit arrangement includes at least three conductive structures levels and elongated interconnects.
    Type: Grant
    Filed: September 21, 2006
    Date of Patent: February 2, 2010
    Assignee: Infineon Technologies AG
    Inventors: Martina Hommel, Heinrich Koerner, Markus Schwerd, Martin Seck
  • Patent number: 7653103
    Abstract: A pulse oscillating type solid laser unit that has a laser unit body whose exciting source is a laser diode that emits light in a principal energy absorbing spectrum of a solid laser activated media, and characterized by that prior to radiating laser light outside the laser unit body as a calibrating operation of a pulse laser output value, specified several varieties of rectangle pulse current values are conducted to a laser diode inside the pulse oscillating type solid laser unit so as to pulse-oscillate the laser unit body, a mean laser output value in each rectangle pulse current value is measured by the use of a laser output measuring instrument arranged inside the laser unit body so as to obtain a mean laser output value data, and in case that the laser output light is radiated outside the laser unit body, a pulse current value linear-predicted based on an obtained mean output value data is conducted to the laser diode so as to obtain a desired pulse laser output value.
    Type: Grant
    Filed: April 19, 2007
    Date of Patent: January 26, 2010
    Assignee: Kataoka Corporation
    Inventor: Nobuaki Iehisa
  • Patent number: 7653102
    Abstract: High-speed measurements of the output power level of a laser are obtained by using a high-speed laser output power monitoring device that is capable of producing an electrical feedback signal having an amplitude that varies as the output power level of the laser varies. A high-speed amplitude detector receives the electrical feedback signal and detects the amplitude of the feedback signal and produces an optical modulation amplitude (OMA) detection signal. The OMA detection signal is received in a high-speed amplitude measurement device that measures the OMA and produces an OMA measurement value. The OMA measurement value is then processed by the laser controller to obtain a modulation current control signal, which is then output to the laser driver to cause the laser driver to adjust the laser modulation current to obtain a desired or optimum laser output power level.
    Type: Grant
    Filed: January 25, 2007
    Date of Patent: January 26, 2010
    Assignee: Avago Technologies Fiber IP (Singapore) Pte. Ltd.
    Inventor: Frederick W. Miller
  • Patent number: 7653101
    Abstract: A semiconductor laser light emitting circuit includes a semiconductor laser diode emitting a laser light by modulating a current supplied thereto, a light intensity detection circuit that detects the laser light and generates a voltage, and a voltage-current conversion circuit converting a voltage into a current supplied to the laser diode. A S/H capacitance is provided to store electric charge and output a voltage to the voltage/current conversion circuit. A first operational amplifier is provided to output a first current charging the S/H capacitance. A rapidly charging circuit is provided to charge the S/H capacitance with a second current. The rapidly charging circuit terminates charging when the voltage is equal to or more than a second reference voltage.
    Type: Grant
    Filed: March 3, 2008
    Date of Patent: January 26, 2010
    Assignee: Ricoh Company, Ltd.
    Inventors: Junichi Ikeda, Hiroaki Kyougoku
  • Patent number: 7649917
    Abstract: The invention relates to a method and system for providing a set of continuous tuning regions from a discontinuously tuned laser, by providing a wavelength reference having at least first and second resonance peaks, sweeping the laser across a pre-determined wavelength range of the wavelength reference, and defining, within the laser sweep, one or more regions of continuous tuning operation of the laser, each of the regions corresponding to a response of the laser between adjacent resonance peaks of the wavelength reference. The advantage of the invention is that it provides a way for stitching together continuous regions of a multi-section tunable laser in an efficient and accurate manner.
    Type: Grant
    Filed: April 14, 2004
    Date of Patent: January 19, 2010
    Assignee: Intune Technologies Limited
    Inventors: Tommy Mullane, David McDonald, Thomas Farrell, Ciaran Polley, Peter B. O'Connor
  • Patent number: 7649919
    Abstract: An automatic power control (APC) circuit applicable to controlling a laser generation module including a laser generator for generating laser and a photosensor for outputting a detection result corresponding to the power of the laser, includes: a comparator, coupled to the photosensor and biased by a first voltage level, for comparing the detection result and a reference signal to generate a comparison result; a level shifter, coupled the comparator, for shifting an intermediate voltage level controlled by the comparison result to generate a control voltage; and a driver, coupled to the level shifter and the laser generator, for driving the laser generator according to the control voltage and a second voltage level.
    Type: Grant
    Filed: May 26, 2006
    Date of Patent: January 19, 2010
    Assignee: MediaTek Inc.
    Inventor: Chien-Ming Chen
  • Patent number: 7643522
    Abstract: A gas discharge laser system bandwidth control mechanism and method of operation for controlling bandwidth in a laser output light pulse generated in the gas discharge laser system is disclosed which may comprise a bandwidth controller which may comprise an active bandwidth adjustment mechanism; a controller actively controlling the active bandwidth adjustment mechanism utilizing an algorithm implementing bandwidth thermal transient correction based upon a model of the impact of laser system operation on the wavefront of the laser light pulse being generated and line narrowed in the laser system as it is incident on the bandwidth adjustment mechanism. The controller algorithm may comprises a function of the power deposition history in at least a portion of an optical train of the gas discharge laser system, e.g., a linear function, e.g., a combination of a plurality of decay functions each comprising a respective decay time constant and a respective coefficient.
    Type: Grant
    Filed: October 20, 2005
    Date of Patent: January 5, 2010
    Assignee: Cymer, Inc.
    Inventors: Fedor B. Trintchouk, Robert N. Jacques
  • Patent number: 7643525
    Abstract: A laser driver comprises a plurality of current sources, including at least one bias current source and at least two drive current sources. To control the laser driver, a set of operating states is defined where each operating state corresponds to a desired laser output power level and a ratio is defined that establishes a relationship between a first desired laser output and a second desired laser output. A calibration operation samples laser output power of the laser source for less than all of the operating states, computes adjustments to the current levels of the current sources based at least in part upon the ratio such that sampled laser power levels converge towards their corresponding desired laser output level. The current sources are adjusted to their corresponding computed current levels.
    Type: Grant
    Filed: October 31, 2007
    Date of Patent: January 5, 2010
    Assignee: Lexmark International, Inc.
    Inventors: Philip Jerome Heink, Daniel Richard Klemer, Stanley Coy Tungate, Jr., Eric Wayne Westerfield
  • Patent number: 7630426
    Abstract: A wavelength detector detecting a change of a wavelength of a laser light with high accuracy, such that the wavelength detector includes a diffraction grating diffracting a laser light, photodetectors positioned symmetrically with respect to a 0-order diffracted light diffracted by the diffraction grating, and respective light incidence surfaces of the photodetectors that have a same shape and that are divided into a plurality of areas. The wavelength detector detects the change of the wavelength based on a value obtained by dividing a difference between (i) a sum of light intensities measured by all of the plurality of divided areas of a first photodetector and (ii) a sum of light intensities measured by all of the plurality of divided areas of a second photodetector, by a sum of light intensities measured by all of the plurality of divided areas of both photodetectors.
    Type: Grant
    Filed: March 14, 2008
    Date of Patent: December 8, 2009
    Assignee: Panasonic Corporation
    Inventors: Kenji Nakayama, Shinichi Kadowaki
  • Patent number: 7620081
    Abstract: A system for real-time linewidth reduction in an optical source includes a laser device comprising a back facet, wherein the laser device receives a modulated input current and generates an optical output signal; an etalon device disposed adjacent to the back facet of the laser device, wherein the etalon device receives an optical feedback output signal from the back facet of the laser device, and wherein the etalon device monitors the optical feedback output signal for changes in frequency and, if they exist, generates an optical correction output signal; a photo-detector device disposed adjacent to the etalon device, wherein the photo-detector device receives the optical feedback and correction output signals, and wherein the photo-detector device converts the optical feedback and correction output signals into an electrical signal; and a feedback correction loop coupled to the photo-detector device, wherein the feedback correction loop receives the electrical signal from the photo-detector device and gener
    Type: Grant
    Filed: September 21, 2006
    Date of Patent: November 17, 2009
    Assignee: Ciena Corporation
    Inventor: Michael Haidar Shahine
  • Patent number: 7620083
    Abstract: A semiconductor laser drive system and a semiconductor laser driving method where both internal noise and optical feedback noise can be simultaneously reduced are provided at low cost and low power consumption.
    Type: Grant
    Filed: August 31, 2006
    Date of Patent: November 17, 2009
    Assignee: National University Corporation Kanazawa University
    Inventor: Minoru Yamada
  • Patent number: 7620082
    Abstract: A method for seeding and stabilizing an optical device, wherein the optical device includes one of a continuous wave laser, a pulsed laser, and a parametric system, the method including seeding the optical device with a seed signal, generating a feedback signal from an output of the optical device, and adjusting a wavelength of the seed signal to maintain a stable operation of the optical device based on the feedback signal. An apparatus, including an optical device having a cavity, a seed laser for generating a seed signal coupled to the optical device, a feedback generator coupled to the output of the optical device for generating a feedback signal, and means for adjusting a wavelength of the seed laser to maintain a stable operation of the optical device based on the feedback signal.
    Type: Grant
    Filed: April 30, 2007
    Date of Patent: November 17, 2009
    Assignee: The Regents of the University of California
    Inventor: Wytze E. van der Veer
  • Publication number: 20090274471
    Abstract: An optical network terminal is provided for use in a passive optical network (PON). The optical network terminal includes a data port for receiving data packets from an external device and a processor for converting the data packets to data link frames. In addition, the optical network terminal includes a memory configured to store a time division multiplexing scheme identifying a time slot assigned to each of a plurality of network nodes in the PON for transmission of upstream optical signals. An optical transceiver is provided for converting the data link frames to upstream optical signals and transmitting the optical signals on an upstream TDMA (time division, multiple access) channel to an Optical Line Terminal (OLT). The optical transceiver includes a burst mode laser diode for generating the optical signals and a burst mode laser driver for biasing the laser diode with a bias signal and a modulation bias signal. The laser driver includes a dual closed loop feedback control circuit.
    Type: Application
    Filed: April 30, 2008
    Publication date: November 5, 2009
    Inventors: David B. Bowler, James M. Aufiero, Francis J. Calabresi, Christopher J. Pekalsky
  • Patent number: 7613216
    Abstract: A laser frequency stabilizing apparatus stabilizes an oscillation frequency of laser light by varying a resonator length on the basis of a saturated absorption line included in an optical output signal. The optical output signal is obtained by irradiating an absorption cell with the laser light. The laser frequency stabilizing apparatus includes: a light detecting section for detecting the optical output signal; a differential signal detecting section for detecting a differential signal of the optical light signal; an actuator for varying the resonator length; a drive section for driving the actuator; and a control section for controlling the drive section on the basis of the differential signal.
    Type: Grant
    Filed: November 30, 2007
    Date of Patent: November 3, 2009
    Assignee: Mitutoyo Corporation
    Inventor: Hideyuki Nakagawa
  • Patent number: 7608806
    Abstract: A method and apparatus is disclosed for optic signal power control to maintain a desired or optimum optic signal power level. During start-up, a default or target value from memory may be utilized to bias or otherwise control operation of an optic signal generator or driver. During operation, one or more parameters or aspects of the optic module or the environment may be monitored. In response to the monitoring one or more control signal may be generated to created to modify bias level, modulation level, or both. The monitoring may monitor the optic signal itself. The bias level and modulation level may be changed simultaneously.
    Type: Grant
    Filed: May 20, 2005
    Date of Patent: October 27, 2009
    Assignee: Mindspeed Technologies, Inc.
    Inventors: Daniel Draper, Maurice M. Reintjes, Gilberto I. Sada, Keith R. Jones
  • Patent number: 7606273
    Abstract: An efficient and low-noise solid-state laser is optically pumped by one or more laser diode(s) driven by RF modulated current. The solid-state laser operation is stabilized by the pump source stable in both spectrum and intensity, in conjunction with automatic power control wherein the feedback loop accurately reflects the true drift in the output power. Moreover, the pump efficiency is optimized and the optical noise is minimized by adjusting the diode operation temperature such that the pump wavelength coincides with the absorption peak of the gain medium. By internally or externally modulating the amplitude of the drive current, the pump diode(s) operate in pulsed mode with controllable shape, width, repetition rate, and pulse-to-pulse intervals, which enables essentially constant optical energy produced from each pulse of the solid-state laser in high repetition rates with variable pulse-to-pulse intervals.
    Type: Grant
    Filed: October 15, 2007
    Date of Patent: October 20, 2009
    Inventors: Sheng-Bai Zhu, Ningyi Luo, Jing Yu
  • Patent number: 7602825
    Abstract: Techniques and devices to stabilize a passively mode-locked laser against the timing jitter by using a feedback control signal based on a signal component at a high harmonic frequency of the laser pulse repetition frequency in the laser output to control the optical path length of the laser resonator.
    Type: Grant
    Filed: September 9, 2005
    Date of Patent: October 13, 2009
    Assignee: Calmar Optcom, Inc.
    Inventors: Anthony Hong Lin, Jingjun Zhao
  • Publication number: 20090252187
    Abstract: The present invention relates generally to semiconductor lasers and laser projection systems. According to one embodiment of the present invention, a projected laser image is generated utilizing an output beam of the semiconductor laser. A gain current control signal is generated by a laser feedback loop to control the gain section of the semiconductor laser. Wavelength fluctuations of the semiconductor laser are narrowed by incorporating a wavelength recovery operation in a drive current of the semiconductor laser and by initiating the wavelength recovery operations as a function of the gain current control signal or an optical intensity error signal. Additional embodiments are disclosed and claimed.
    Type: Application
    Filed: December 12, 2008
    Publication date: October 8, 2009
    Inventors: Anthony Sebastian Bauco, Douglas Llewellyn Butler, Martin Hai Hu, Dragan Pikula, Daniel Ohen Ricketts
  • Publication number: 20090245305
    Abstract: Disclosed is a laser system comprising: A laser assembly (101) comprising a plurality of emitters; first and second light feedback devices (208, 232) forming respective external cavities with the laser assembly; a dispersive device (205) for redirecting respective portions of the light from the laser assembly to the first and second feedback devices (208, 232), wherein the first feedback device (232) is adapted to reflect a feedback portion of the redirected beam back onto the dispersive device (205) and to generate the output beam (233) from an output part of the first redirected beam, —an imaging device (213) for generating an optical Fourier transform of the plurality of emitters at a Fourier plane (235). The dispersive device (205) is positioned displaced from said Fourier plane (235) by a predetermined displacement (d) in a direction along said principle axis (230).
    Type: Application
    Filed: December 5, 2006
    Publication date: October 1, 2009
    Applicant: Danmarks Tekniske Universitet
    Inventors: Ole Bjarlin Jensen, Birgitte Thestrup Nielsen, Paul Michael Petersen
  • Publication number: 20090245306
    Abstract: This invention relates to opto-electronic systems using semiconductor lasers driven by optical phase-locked loops that control the laser's optical phase and frequency. Feedback control provides a means for precise control of optical frequency and phase, including the ability for broadband electronic tunability of optical signals and the cascading of multiple lasers for enhanced tunability and coherent combining for increased output power.
    Type: Application
    Filed: April 1, 2009
    Publication date: October 1, 2009
    Applicant: TELARIS INC.
    Inventor: George A. Rakuljic
  • Publication number: 20090225800
    Abstract: The subject of the invention is a laser comprising a semiconductor active medium with a population inversion lifetime ?c and a resonant cavity with a lifetime of the photons in the cavity ?p. The cavity includes means for being longitudinally monomode and means so that ?p>?c, such as for example a very long cavity, so as to obtain a laser with a very low intrinsic noise.
    Type: Application
    Filed: June 7, 2006
    Publication date: September 10, 2009
    Inventors: Mehdi Alouini, Ghaya Baili, Chantal Moronvalle, Fabien Bretenaker, Daniel Dolfi
  • Publication number: 20090225801
    Abstract: The present invention provides a semiconductor optical element applicable to an EC-LD or an SLD, and an external cavity laser having the semiconductor optical element. The semiconductor optical element has a pair of cleavage surfaces, and comprises a semiconductor substrate 11 having a base surface and a planer structure provided on the base surface and provided with a waveguide 1G having an active layer. The waveguide 1G has an end surface with low reflectivity and another end surface with certain reflectivity.
    Type: Application
    Filed: September 27, 2006
    Publication date: September 10, 2009
    Inventors: Hiroshi Mori, Atsushi Yamada, Takahiro Samejima
  • Publication number: 20090225798
    Abstract: An optical apparatus comprising a gain medium exhibiting polarisation dependent absorption along two axes, the gain medium having a weakly absorbing axis and a strongly absorbing axis, an optical pump source arranged to direct pump light towards a first face of the gain medium such that the pump light entering the gain medium has a component of its polarisation parallel to the weakly absorbing axis, a polarisation modifying apparatus and one or more reflectors which are together arranged to modify the polarisation of pump light which exits the gain medium through a second face of the gain medium, and to direct the pump light with modified polarisation back towards said second face of the gain medium.
    Type: Application
    Filed: January 5, 2009
    Publication date: September 10, 2009
    Inventors: Alan M. Cox, Jean-Charles Cotteverte
  • Patent number: 7583711
    Abstract: Method and apparatus are disclosed that enable lasers to be stabilized in absolute frequency to high precision. The principle of operation is to: 1) lock the laser frequency to an etalon transmission resonance, 2) phase modulate the laser beam at a frequency corresponding to the free spectral range of the etalon and lock the phase modulated sidebands to the etalon resonances, and 3) lock the etalon free spectral range frequency to a stable reference frequency derived from, e.g., a stable crystal oscillator. The result is that the laser frequency is locked to an integer multiple of the reference frequency. The invention has applicability to numerous situations where a stable frequency must be provided at a specific value, and has further applicability to stabilizing multiple lasers in different locations to the same value.
    Type: Grant
    Filed: March 17, 2006
    Date of Patent: September 1, 2009
    Assignee: Lockheed Martin Coherent Technologies, Inc.
    Inventor: Bruce Tiemann
  • Publication number: 20090213882
    Abstract: A laser source (10) for emitting a set of sequential, different wavelength output beams (12) includes a gain medium (16), a feedback assembly (26) and a control system (30). The gain medium (16) includes a first facet (16A), and the gain medium (16) generates a beam (12A) that exits the first facet (16A). The feedback assembly (26) includes a feedback device (40) and a device mover (42). The feedback device (40) is positioned in the path of the beam (12A) that exits the first facet (16A) and the feedback device (40) redirects at least a portion of the beam (12A) back to the gain medium (16). The device mover (42) continuously adjusts an angle of incidence (?) of the beam (12A) on the feedback device (40). The control system (30) selectively directs pulses of power to the gain medium (16) as the device mover (42) is continuously adjusting the angle of incidence (?) of the beam (12A).
    Type: Application
    Filed: January 13, 2009
    Publication date: August 27, 2009
    Inventors: Miles James Weida, Russ Pritchett, David F. Arnone
  • Publication number: 20090201955
    Abstract: The disclosure relates to an illuminating apparatus for illuminating a sample on a work stage, optionally with a relatively narrow illuminating line of relatively controlled energy, as well as methods for controlling energy of a laser source when illuminating a sample on a work stage with a relatively narrow illuminating line.
    Type: Application
    Filed: February 7, 2008
    Publication date: August 13, 2009
    Inventors: Bernhard Weigl, Rick Sandstrom
  • Patent number: 7564881
    Abstract: The invention discloses an optical transmission module with digital adjustment and method thereof. The module includes a laser (21), a laser driver (22), an automatic power adjustment circuit (23), an automatic temperature adjustment circuit (24), a digital adjustment circuit (25) and a memory (26). The digital adjustment circuit, consisted of a digital-to-analog converter or a digital adjustment potentiometer, receives a digital adjustment signal and outputs, respectively, a extinction ratio adjustment signal and a cross point adjustment signal to the laser driver, an optical power adjustment signal to the automatic power adjustment circuit and an optical wavelength adjustment signal to the automatic temperature adjustment circuit. The memory stores data, using for on-line adjustment of the optical transmission module, at least including parameters of said optical transmission module and said laser emitting optical power parameters, to be reported upward.
    Type: Grant
    Filed: July 26, 2004
    Date of Patent: July 21, 2009
    Assignee: Huawei Technologies Co., Ltd.
    Inventor: Tianhai Chang
  • Publication number: 20090161707
    Abstract: The luminance of a laser diode is a function of laser diode drive current. The luminance is also a function of other factors, such as age and temperature. A laser projection device includes laser diodes to generate light in response to a commanded luminance, and also includes photodiodes to provide a measured luminance. The commanded luminance and measured luminance are compared, and drive currents for the laser diodes are adjusted to compensate for changes in laser diode characteristics.
    Type: Application
    Filed: December 21, 2007
    Publication date: June 25, 2009
    Applicant: Microvision, Inc.
    Inventors: Mark Champion, Heng Huang
  • Publication number: 20090154511
    Abstract: A Light receiver generates a monitoring voltage according to an optical output of an LD element. The control circuit obtains a set value according to the ambient temperature around the LD element, and controls the optical output of the LD element on the basis of the comparing the result between the set value and the monitoring voltage. An adjustment section corrects the monitoring voltage on the basis of the set value and outputs the corrected monitoring voltage.
    Type: Application
    Filed: December 11, 2008
    Publication date: June 18, 2009
    Inventor: Munetoshi Yoshizawa
  • Patent number: 7548570
    Abstract: In a laser power control apparatus for controlling a laser power of a combination drive, first laser light Lc applied onto a first optical disk and second laser light Ld applied onto a second optical disk is collected by one photodetector 8.
    Type: Grant
    Filed: June 18, 2007
    Date of Patent: June 16, 2009
    Assignee: Panasonic Corporation
    Inventors: Masamichi Katada, Motonori Taniguchi