Operating Frequency Patents (Class 359/341.31)
  • Patent number: 9871336
    Abstract: The present application provides an optical system. The optical system includes a fiber amplifier with an optically active doped fiber, a source of seed pulses, and a pump source. The doped fiber is doped with one or more active element(s) selected such that the seed pulses are amplified in intensity. The doped fiber has a negative (anomalous) group velocity dispersion in the region from the wavelength of the seed pulses to a threshold wavelength at which the magnitude of the optical loss of the doped fiber is greater than a gain due to stimulated Raman scattering.
    Type: Grant
    Filed: May 5, 2014
    Date of Patent: January 16, 2018
    Assignee: ATLA LASERS AS
    Inventors: Vladislav Vladimirovich Dvoyrin, Irina T. Sorokina
  • Patent number: 9563011
    Abstract: In some embodiments, an optical transmission system includes a few-mode fiber that supports at least 2 spatial modes but no more than 50 spatial modes.
    Type: Grant
    Filed: January 27, 2011
    Date of Patent: February 7, 2017
    Assignee: University of Central Florida Research Foundation, Inc.
    Inventors: Guifang Li, Fatih Yaman, Xiaobo Xie, Likai Zhu, Neng Bai, Cen Xia
  • Patent number: 9553417
    Abstract: System for converting relatively long pulses from rep-rate variable ultrafast optical sources to shorter, high-energy pulses suitable for sources in high-energy ultrafast lasers. Fibers with positive group velocity dispersion (GVD) and self phase modulation are advantageously employed with the optical sources. These systems take advantage of the need for higher pulse energies at lower repetition rates so that such sources can be cost effective.
    Type: Grant
    Filed: October 17, 2013
    Date of Patent: January 24, 2017
    Assignee: IMRA AMERICA, INC.
    Inventor: Donald J. Harter
  • Patent number: 9256114
    Abstract: A supercontinuum generation system comprises a noise-like pulse fiber laser structure, an amplification unit and a broadening medium. The noise-like pulse fiber laser structure generates at lease one noise-like pulse of the wavelength less than 1300 nm. The amplification unit includes a gain fiber with which the noise-like pulse is coupled. The broadening medium is coupled with the gain fiber. A supercontinuum is generated when the noise-like pulse is amplified by the amplification unit and broadened in spectrum by the broadening medium.
    Type: Grant
    Filed: September 11, 2013
    Date of Patent: February 9, 2016
    Assignee: NATIONAL TSING HUA UNIVERSITY
    Inventors: Ci-Ling Pan, Alexey Zaytsev, Chih-Hsuan Lin, Yi-Jing You
  • Patent number: 9025240
    Abstract: A peak value detector detects power of an output light pulse which is output from the light amplifying fiber. A light receiving element receives a group of light pulses including a plurality of pulses and converts the group of light pulses into a current signal. The current/voltage converter circuit converts the current output from the light receiving element to voltage. The integration circuit integrates the voltage output from the current/voltage converter circuit. A programmable gain amplifier (PGA) amplifies the signal output from the integration circuit and provides the signal for the A/D converter circuit. The gain of the PGA is set by a gain setting signal from the signal processing circuit. The signal processing circuit adjusts the gain of the PGA so that the gain increases as the repetition frequency of the group of pulses increases.
    Type: Grant
    Filed: May 10, 2012
    Date of Patent: May 5, 2015
    Assignee: Omron Corporation
    Inventor: Tatsuo Ogaki
  • Publication number: 20150029581
    Abstract: Stimulating emission via thulium's lasing transition from the 3H4 manifold to the 3H6 manifold yields light at wavelength of about 820 nm. Unfortunately, excited thulium ions also transition from the 3H4 manifold to the long-lived 3F4 manifold, where they become trapped and can no longer participate in the lasing transition. If the enough of the thulium population becomes trapped in the 3F4 manifold, the gain medium becomes transparent at the pump wavelength, rendering population inversion difficult or impossible. Fortunately, the size of the population in the 3F4 manifold can be limited by selecting an appropriate crystal host and thulium doping concentration, pumping the thulium with pulses shorter than the 3F4 manifold's lifetime, cooling the gain medium to low temperature (e.g., 77 K), stimulating emission from the 3F4 manifold, upconversion pumping of the thulium from the 3F4 manifold to the 3H4 manifold, or transferring energy from thulium in the 3F4 manifold to a co-dopant.
    Type: Application
    Filed: July 24, 2013
    Publication date: January 29, 2015
    Applicant: Massachusetts Institute of Technology
    Inventor: Tso Yee Fan
  • Publication number: 20150015939
    Abstract: An optical pumping apparatus for few-mode fiber amplification is provided. The optical pumping apparatus includes an optical pump source configured to generate an optical pump; an optical power divider configured to divide an optical power of the optical pump from the optical pump source so as to output several optical pumps with uniformly distributed optical power; and a modal multiplexer configured to receive the optical pumps from the optical power divider through a plurality of single-mode fibers, multiplex the received optical pumps, apply a multiplexed optical pump to each mode of a few-mode fiber (FMF) amplifier, and adjust a gain difference among modes, wherein the FMF amplifier obtains a gain by amplifying an optical signal with the optical pump.
    Type: Application
    Filed: June 18, 2014
    Publication date: January 15, 2015
    Inventors: Sun-Hyok CHANG, Hwan-Seok CHUNG
  • Patent number: 8902492
    Abstract: An optical amplifier includes: a temperature-adjustment-unit that is provided in a wavelength-fixing-unit that fixes a center-wavelength of an excitation-light-source, and adjusts a temperature of the wavelength-fixing-unit, which causes the center-wavelength of the excitation-light-source to vary; a temperature-measurement-unit that measures the temperature of the wavelength-fixing-unit and a temperature of a gain-equalization-unit that equalizes gains of the signal-light on which the Raman amplification is performed using the excitation-light-source; a shift-amount-obtaining-unit that obtains a shift amount data of the center-wavelength of the excitation-light-source from a first-storage-unit and obtains a shift amount of the center-wavelength of the wavelength-band from a second-storage-unit; and a control unit that obtains a temperature-data of the-wavelength-fixing-unit, which corresponds to a difference between two shift amounts that are obtained by the shift amount obtaining unit, from the first-storag
    Type: Grant
    Filed: April 25, 2013
    Date of Patent: December 2, 2014
    Assignee: Fujitsu Limited
    Inventor: Yuichi Suzuki
  • Patent number: 8867123
    Abstract: A high-power pulse light generator includes: a master oscillator generating oscillated pulse light in synchronization with a master clock signal; an optical amplifier amplifying the oscillated pulse light output from the master oscillator and outputting high-power pulsed light; a driving unit driving a pumping semiconductor laser in synchronization with the master clock signal; and a control unit controlling the driving unit so that the driving current to be supplied to the pumping semiconductor laser becomes lower than or equal to a set value at which the pumping semiconductor laser is not in a laser oscillation state when returning light from an irradiated body with the high-power pulsed light reaches the pumping semiconductor laser connected to the optical amplifier, the control unit determining a timing of the control in accordance with an optical path length between the irradiated body and the pumping semiconductor laser.
    Type: Grant
    Filed: September 6, 2012
    Date of Patent: October 21, 2014
    Assignee: Fujikura Ltd.
    Inventors: Michihiro Nakai, Yasuhiro Oba
  • Publication number: 20140036351
    Abstract: An optical fiber coupler connects transmission multicore optical fiber (TMCF) with an amplifier multicore optical fiber (AMCF) and a plurality of optical pump fibers. The coupler includes a plurality of signal cores extending between a multicore input endface and a coupler output endface, and a plurality of pump cores extending between a pump input and the coupler output endface. The multicore input endface is connectable to the TMCF, and the pump input is connectable to the optical pump fibers. Each pump core is paired with a corresponding signal core to form a core pair that is adiabatically tapered such that signal light carried by the signal core is combined with pump light carried by the pump core. The coupler output endface is connectable to the AMCF such that the combined light output of each core pair is provided as an input to a respective AMCF core.
    Type: Application
    Filed: July 29, 2013
    Publication date: February 6, 2014
    Inventors: John M. Fini, Thierry F. Taunay, Man F. Yan, Benyuan Zhu
  • Publication number: 20130271824
    Abstract: The invention can include an apparatus for producing optical pulses, comprising an oscillator for producing optical pulses at a first optical pulse repetition frequency, the optical pulses having a first wavelength; a first optical fiber amplifier; a second optical fiber amplifier; a pulse picker located between the first and second optical fiber amplifiers, the pulse picker operable to reduce the optical pulse repetition frequency of optical pulses, wherein the first amplifier amplifies optical pulses at the first optical pulse repetition frequency and the second amplifier amplifies optical pulses at a reduced optical pulse repetition frequency that is less than the first optical pulse repetition frequency; a nonlinear optical fiber receiving amplified optical pulses having the reduced optical pulse repetition frequency and the first wavelength to produce, at the reduced optical pulse frequency, optical pulses that include one or more nonlinearly produced wavelengths different than the first wavelength; and
    Type: Application
    Filed: March 12, 2013
    Publication date: October 17, 2013
    Inventors: John Redvers Clowes, Anatoly Borisovich Grudinin, Ian Michael Godfrey, Kestutis Vysniauskas
  • Patent number: 8509588
    Abstract: An amplifying optical fiber includes a core containing oxides of elements selected from the group consisting of silicon, germanium, phosphorus, bismuth, aluminum, gallium with a concentration of bismuth oxide of 10-4-5 mol %, a total concentration of silicon and germanium oxides of 70-99.8999 mol %, a total concentration of aluminum and gallium oxides of 0.1-20 mol % wherein both aluminum and gallium oxide are present and a ratio of aluminum oxide to gallium oxide is at least two, and a concentration of phosphorus oxide from 0 to 10 mol %, and provides a maximum optical gain at least 10 times greater than the nonresonant loss factor in the optical fiber. An outside oxide glass cladding comprises fused silica. The core has an absorption band in the 1000 nm region, pumping to which region provides an increased efficiency of power conversion of pump light into luminescence light in the 1000-1700 nm range.
    Type: Grant
    Filed: September 8, 2006
    Date of Patent: August 13, 2013
    Assignee: Fiber Optics Research Center of The Russian Academy of Sciences
    Inventors: Evgeny Mikhailovich Dianov, Vladislav Vladimirovich Dvoirin, Valery Mikhailovich Mashinsky, Alexei Nikolaevich Guryanov, Andrei Alexandrovich Umnikov
  • Patent number: 8498045
    Abstract: An optical amplifier includes a rare-earth doped optical fiber for receiving input light through one end and outputting output light through another end, the input light being input from an input port; an excitation light source for generating excitation light; an optical coupler for supplying the generated excitation light to the one end and/or the another end of the rare-earth doped optical fiber; and a reflector for reflecting an amplified spontaneous emission light out of a signal band traveling in opposite direction to the input light, the amplified spontaneous emission light being generated in the rare-earth doped optical fiber.
    Type: Grant
    Filed: September 9, 2010
    Date of Patent: July 30, 2013
    Assignee: Fujitsu Limited
    Inventor: Tomoaki Takeyama
  • Publication number: 20120320451
    Abstract: A very large more area active double clad optical waveguide doped with Nd3+ at a concentration of at least 0.1% by weight can be used to effectively amplify light at a wavelength of between 1050 nm and 1120 nm. At a doping concentration sufficient to provide a net optical absorption of at least 3 dB/m for the pump light at the wavelength of 795 to 815 nm or 883 to 887 nm, Nd3+ operates under much lower inversion levels than Yb3+. Due to the lower inversion levels, the Nd3+ doped waveguide is subject to reduced pump bleaching or photodarkening.
    Type: Application
    Filed: June 13, 2012
    Publication date: December 20, 2012
    Applicant: JDS Uniphase Corporation
    Inventor: Martin H. MUENDEL
  • Patent number: 8300306
    Abstract: A Raman amplifier includes at least a first and a second optical Raman-active fiber disposed in series with each other. A first pump source is connected to the first Raman-active fiber, and is adapted for emitting and coupling into the first Raman-active fiber a first pump radiation including a first group of frequencies. A second pump source is connected to the second Raman-active fiber, and is adapted for emitting and coupling into the second Raman-active fiber a second pump radiation including a second group of frequencies. The whole of said first and second group of frequencies extends over a pump frequency range having a width of at least the 40% of the Raman shift. The minimum and the maximum frequency in each of said first and second group of frequencies differ with each other of at most the 70% of said Raman shift.
    Type: Grant
    Filed: October 4, 2010
    Date of Patent: October 30, 2012
    Assignee: Google Inc.
    Inventors: Attilio Bragheri, Giulia Pietra, Raffaele Corsini, Danilo Caccioli
  • Patent number: 8233216
    Abstract: The alteration of the bandwidth of an optical amplifier. Before alteration, optical signals having a first set of wavelengths are provided through a gain medium of the optical amplifier. In addition, a first pump having a set of pump wavelengths is propagated through the gain medium to thereby amplify the optical signals. After alteration, optical signals having at least a partially different set of wavelengths are able to be optically amplified by coupling a second pump into the optical medium. The second pump is at least partially distinct from the first pump in that the second pump includes at least one pump wavelength that was not included in the first pump.
    Type: Grant
    Filed: January 7, 2009
    Date of Patent: July 31, 2012
    Assignee: Xtera Communications, Inc.
    Inventors: Do-Il Chang, Wayne S. Pelouch, Herve A. Fevrier
  • Patent number: 7970241
    Abstract: A modulator includes an electro-optical substrate and a first and second waveguide formed of a doped semiconductor material positioned on a surface of an electro-optical substrate forming a slot therebetween. A doping level of the semiconductor material being chosen to make the first and second waveguide conductive. A dielectric material is positioned in the slot which increases confinement of both an optical field and an electrical field inside the slot. A refractive index of the semiconductor material and a refractive index of the dielectric material positioned in the slot being chosen to reduce the V?·L product of the modulator.
    Type: Grant
    Filed: September 9, 2008
    Date of Patent: June 28, 2011
    Assignee: Photonic Systems, Inc.
    Inventors: Jianxiao Chen, Charles Cox
  • Patent number: 7872794
    Abstract: An apparatus and that provide an optical-fiber amplifier having at least one erbium-doped fiber section and an optical pump coupled to the erbium-doped fiber section, wherein the apparatus is operable to amplify signal pulses to high energy in the erbium-doped fiber section, the pulses having a wavelength in the range of about 1565 nm to about 1630 nm. In some embodiments, the amplifying fiber is ytterbium free.
    Type: Grant
    Filed: January 22, 2008
    Date of Patent: January 18, 2011
    Assignee: Lockheed Martin Corporation
    Inventors: John D. Minelly, Deborah A. Alterman
  • Patent number: 7813034
    Abstract: A Raman amplifier comprises at least a first and a second optical Raman-active fiber disposed in series with each other. A first pump source is connected to the first Raman-active fiber, and is adapted for emitting and coupling into the first Raman-active fiber a first pump radiation including a first group of frequencies. A second pump source is connected to the second Raman-active fiber, and is adapted for emitting and coupling into the second Raman-active fiber a second pump radiation including a second group of frequencies. The whole of said first and second group of frequencies extends over a pump frequency range having a width of at least the 40% of the Raman shift. The minimum and the maximum frequency in each of said first and second group of frequencies differ with each other of at most the 70% of said Raman shift.
    Type: Grant
    Filed: May 18, 2007
    Date of Patent: October 12, 2010
    Assignee: PGT Photonics S.p.A.
    Inventors: Attilio Bragheri, Giulia Pietra, Raffaele Corsini, Danilo Caccioli
  • Patent number: 7768698
    Abstract: A Raman amplifier includes a pumping light source, an optical coupler, and a Raman amplifier medium. The pumping light source outputs a pumping light that is intensity-modulated with a frequency equal to or higher than 100 megahertz. The optical coupler couples the pumping light with a carrier light. The Raman amplification medium is pumped by the pumping light to amplify the carrier light. The Raman amplification medium has characteristics of a low dispersion and a small difference between propagation times of the carrier light and the pumping light.
    Type: Grant
    Filed: August 30, 2004
    Date of Patent: August 3, 2010
    Assignees: Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology, Mitsubishi Electric Corporation
    Inventors: Toshiyuki Tokura, Katsuhiro Shimizu, Tasuku Fujieda, Ken'ichi Asakawa, Hitoshi Mikada, Katsuyoshi Kawaguchi
  • Publication number: 20100157419
    Abstract: The invention is directed to a high power short optical pulse source 10 comprising a master oscillator 12 and a Ytterbium doped fibre amplifier (YDFA) preamplifier 14, a pump light source 16, an optical head 18, high power optical fibre amplifier means 20, an optical signal delivery fibre 22, and a pump light delivery fibre 24. The master oscillator 12, preamplifier 14, and pump laser 16, together with their associated drive and control electronics, and cooling systems, are provided within a first enclosure 28 at a first location. The high power fibre amplifier means 20 comprises a Ytterbium doped amplifier fibre and a pump signal combiner. The high power fibre amplifier means 20 is provided within the optical head 18, which is located at a second location, remote from the first location. The optical head 18 has a small footprint and can be positioned at the intended target of the optical pulses.
    Type: Application
    Filed: January 18, 2007
    Publication date: June 24, 2010
    Inventors: John Redvers Clowes, Anatoly Borisovich Grudinin, Ian Michael Godfrey, Kestutis Vysniauskas
  • Patent number: 7692852
    Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.
    Type: Grant
    Filed: March 21, 2007
    Date of Patent: April 6, 2010
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Youichi Akasaka, Yoshihiro Emori, Shu Namiki
  • Publication number: 20100046067
    Abstract: A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Modularity is ensured by the implementation of interchangeable amplifier components. System compactness is ensured by employing efficient fiber amplifiers, directly or indirectly pumped by diode lasers. Peak power handling capability of the fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-phase modulation and gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple fiber delay lines or chirped fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers.
    Type: Application
    Filed: October 29, 2009
    Publication date: February 25, 2010
    Applicant: IMRA AMERICA, INC.
    Inventors: Martin E. FERMANN, Almantas GALVANAUSKAS, Donald J. HARTER
  • Patent number: 7609438
    Abstract: The present invention relates to an optical amplifier provided with a plurality of optically cascade-connected amplification units and also with a structure for enabling suppression of transient gain variations as a whole. Each of the plurality of amplification units in the optical amplifier has a pumping light source and an amplifying optical fiber, and at least one selected from the plurality of amplification units includes a timing adjustment system for temporally moving back or forth the variation timing of pumping light power accompanying the signal light power variation due to the variation of the number of signal channels, with respect to the variation timing of signal light power at a light incident end of the amplifying optical fiber contained in the own amplification unit.
    Type: Grant
    Filed: July 26, 2007
    Date of Patent: October 27, 2009
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventor: Shinobu Tamaoki
  • Patent number: 7586672
    Abstract: A reliable optical transmission system with an improved signal control mechanism that avoids abrupt power variations of light beams, thereby preventing optical supervisory channel (OSC) signals from experiencing errors. An optical amplifier amplifies main signals under the control of an optical amplifier controller, which spends a first predetermined time to raise the output power of the optical amplifier up to a desired level. A pump light source produces a pump beam for injection to a fiber-optic transmission line so as to make it serve as an amplifying medium. The pump light source is controlled by a pump light source controller that spends a second predetermined time to raise the pump beam to a desired power level. This stepwise start-up process of the amplifier power and pump beam power prevents OSC signals from experiencing abrupt power variations.
    Type: Grant
    Filed: June 12, 2007
    Date of Patent: September 8, 2009
    Assignee: Fujitsu Limited
    Inventors: Eiji Ishikawa, Hiroto Ikeda, Hiroyuki Deguchi
  • Publication number: 20090201574
    Abstract: The present invention relates to an optical amplification module having a construction which effectively suppresses photodarkening, and to a laser light source including the same. The laser light source comprises a light source for outputting light to be amplified, and an optical amplification module. The optical amplification module comprises two types of optical amplification media having different rare earth element concentrations, and a pumping light source. The low concentration medium and the high concentration medium are disposed in the propagation direction of pumping light such that the population inversion of the low concentration medium is higher than that of the high concentration medium.
    Type: Application
    Filed: April 14, 2009
    Publication date: August 13, 2009
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Shinobu Tamaoki, Motoki Kakui
  • Patent number: 7440165
    Abstract: Provided is an optical fiber. The optical fiber includes a core and a cladding, the core containing a first element for inducing non-linear Raman phenomenon, and the cladding containing a second element which is a rare earth element, wherein when the optical fiber is pumped by two pumping light sources having different wavelengths with each other, the optical signals in the first and third band are Raman-amplified by the first element and the signals in the second band are amplified by a direct transition of the second element.
    Type: Grant
    Filed: August 3, 2005
    Date of Patent: October 21, 2008
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Hong Seok Seo, Joon Tae Ahn, Woon Jin Chung
  • Publication number: 20080013163
    Abstract: Control of average wavelength-converted power and/or wavelength converted pulse energy is described. One or more seed pulses may be generated and amplified with an optical amplifier to produce one or more amplified pulses. The amplified pulses may be wavelength converted to produce one or more wavelength converted pulses characterized by an average wavelength-converted power or pulse energy. Wavelength-converted power or pulse energy may be controlled by adjusting wavelength conversion efficiency without substantially changing the amplified power or pulse energy. Average wavelength-converted power may be controlled over a time scale comparable to a pulse period of the amplified pulses without adjusting an average power of the amplified pulses over the time scale comparable to a pulse period of the amplified pulses.
    Type: Application
    Filed: July 11, 2006
    Publication date: January 17, 2008
    Applicant: Mobius Photonics, Inc.
    Inventors: Manuel J. Leonardo, Mark W. Byer, Gregory L. Keaton, John Nightingale
  • Patent number: 7269190
    Abstract: An erbium-doped (Er-doped) superfluorescent fiber source (SFS) has an enhanced mean wavelength stability. A method determines an estimated mean wavelength of a SFS. The method includes providing an Er-doped SFS having an actual mean wavelength. The method further includes configuring the SFS such that the actual mean wavelength has a dependence on the temperature of the EDF. The method further includes obtaining the dependence of the actual mean wavelength on the temperature of the EDF. The method further includes measuring the temperature of the EDF. The method further includes calculating the estimated mean wavelength using the measured temperature of the EDF and the dependence of the actual mean wavelength on the temperature of the EDF.
    Type: Grant
    Filed: October 1, 2003
    Date of Patent: September 11, 2007
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Hee Gap Park, Michel J. F. Digonnet, Gordon S. Kino
  • Patent number: 7253944
    Abstract: A Raman amplifier having at least a first and a second optical Raman-active fiber disposed in series with each other is disclosed. A first pump source is connected to the first Raman-active fiber, and is adapted for emitting and coupling into the first Raman-active fiber a first pump radiation including a first group of frequencies. A second pump source is connected to the second Raman-active fiber, and is adapted for emitting and coupling into the second Raman-active fiber a second pump radiation including a second group of frequencies. The whole of the first and second group of frequencies extends over a pump frequency range having a width of at least 40% of the Raman shift. The minimum and the maximum frequency in each of the first and second group of frequencies differ from each other by at most 70% of the Raman shift.
    Type: Grant
    Filed: July 31, 2002
    Date of Patent: August 7, 2007
    Assignee: Pirelli & C. S.p.A.
    Inventors: Attilio Bragheri, Giulia Pietra, Raffaele Corsini, Danilo Caccioli
  • Patent number: 7209603
    Abstract: The device comprises an optical waveguide and an acoustic wave generating device. The waveguide has an optical band gap and a sharp electronic transition (e.g. an excitonic transition) in the band gap, and the acoustic wave generating device generates acoustic waves within the waveguide. Light passing through the waveguide is of a frequency within the band gap of the waveguide and is nearly resonant with the sharp electronic transition. The wave generating device is arranged to generate acoustic waves so as to induce optical band gas in the polariton spectrum, thereby affecting the transmission of the light passing through the waveguide, the transmission of which is thereby affected.
    Type: Grant
    Filed: September 4, 2002
    Date of Patent: April 24, 2007
    Assignees: University College Cardiff Consultants Limited, Cambridge University Technical Services Limited
    Inventors: Peter Brent Littlewood, Alexander L. Ivanov
  • Patent number: 7113328
    Abstract: An arrangement and method provide an optical thulium doped fiber amplifier utilizing a dual wavelength pumping scheme for amplifying an optical signal. The method includes the steps of: a first deposition (a) of energy into the fiber amplifier by pumping with radiation of a first wavelength; and a second deposition (b) of energy into the fiber amplifier by pumping with radiation of a second wavelength. The radiation of the first wavelength is arranged to induce, by single photon absorption, a population to the 3H4 level of the thulium dopant, and the radiation of the second wavelength primarily depopulates the 3F4 level, by excited absorption of a single photon, preferably by strong excited state absorption to the 3F2 level. The steps gives a population inversion between the 3H4 and the 3F4 levels and facilitate a power efficient high gain amplification.
    Type: Grant
    Filed: March 10, 2003
    Date of Patent: September 26, 2006
    Assignee: Telefonaktiebolaget LM Ericsson (publ)
    Inventors: Anderson Stevens Leonidas Gomes, Michael Lee Sundheimer, Mariana Torres Carvalho, Joaquim Ferreira Martins-Filho, Carmelo José Albanez Bastos-Filho, Walter Margulis
  • Patent number: 6970650
    Abstract: In a one-fiber bidirectional optical transmission system in which output optical signals of optical transmitter-receivers respectively connected to the opposite ends of one optical fiber transmission line are bidirectionally transmitted in the optical fiber transmission line, which utilizes a Raman amplification effect by backward pumping, a frequency satisfying the conditions of |fs1?f0|?|fp2?f0| and |fs2?f0|?|fp1?f0| is selected, where f0 is a zero dispersion frequency of the optical fiber transmission line, fs1 and fs2 are the frequencies of the first signal and the second signal, respectively, and fp1 and fp2 are frequencies of the first Raman pump light and the second Raman pump light, respectively.
    Type: Grant
    Filed: February 26, 2003
    Date of Patent: November 29, 2005
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Satoshi Kajiya, Kaoru Kinjo, Takashi Mizuochi
  • Patent number: 6927896
    Abstract: In a Raman optical amplification system in which WDM optical signals comprising two or more signal bands are transmitted in a transmission line, and in which a plurality of pumping lightwaves are introduced into said transmission line so that WDM optical signals in the shortest signal band are Raman-amplified by said plurality of pumping lightwaves, the interval between the longest pumping wavelength and the next-longest pumping wavelength differs by 0.2 to 1.4 THz in frequency. This makes it possible to flatten the level of the WDM signals by means of canceling the Raman gain ripple on the longer wavelength region of the distributed amplification.
    Type: Grant
    Filed: July 12, 2002
    Date of Patent: August 9, 2005
    Assignee: The Furukawa Electric Company, Ltd.
    Inventor: Yoshihiro Emori
  • Patent number: 6922503
    Abstract: An optical module comprises a multiplexer for combining a signal and a pump radiation and having an output coupled to an optical fiber and a signal over the optical fiber with the pump lightwave that has a frequency three times of that of the signal and phase index equal to that of the signal. Phase matching between the pump and signal is realized for example by employing a microstructured optical fiber as the optical fiber.
    Type: Grant
    Filed: April 17, 2003
    Date of Patent: July 26, 2005
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventor: Takemi Hasegawa
  • Patent number: 6897434
    Abstract: A source and/or method of generating quantum-correlated and/or entangled photon pairs using parametric fluorescence in a fiber Sagnac loop. The photon pairs are generated in the 1550 nm fiber-optic communication band and detected by a detection system including InGaAs/InP avalanche photodiodes operating in a gated Geiger mode. A generation rate>103 pairs/s is observed, a rate limited only by available detection electronics. The nonclassical nature of the photon correlations in the pairs is demonstrated. This source, given its spectral properties and robustness, is well suited for use in fiber-optic quantum communication and cryptography networks. The detection system also provides high rate of photon counting with negligible after pulsing and associated high quantum efficiency and also low dark count rate.
    Type: Grant
    Filed: February 28, 2003
    Date of Patent: May 24, 2005
    Assignee: Northwestern University
    Inventors: Prem Kumar, Marco Florentino, Paul L. Voss, Jay E. Sharping
  • Patent number: 6882466
    Abstract: An optical amplifier is provided for performing amplification of optical signals of two wavelength bands, where deterioration in the optical SN ratio relative to one wavelength band is reduced, with a simple construction which can deal with restrictions on installation space, power consumption and the like. To this end, the present optical amplifier has a C/L band optical amplifying section for amplifying respective optical signals of a C band and an L band, a demultiplexer for demultiplexing output light from the C/L band optical amplifying section into the C band and the L band, an L band optical amplifying section for amplifying L band optical signals which have been demultiplexed by the demultiplexer, and a multiplexer for multiplexing the C band optical signals which have been demultiplexed by the demultiplexer and the L band optical signals which have been amplified by the L band optical amplifying section.
    Type: Grant
    Filed: August 9, 2000
    Date of Patent: April 19, 2005
    Assignee: Fujitsu Limited
    Inventors: Naomasa Shimojoh, Takao Naito
  • Patent number: 6870667
    Abstract: Optical amplifier according to the present invention is provided with an EDF, a light source device having a semiconductor laser element that generates an excitation beam and a housing that accommodates this, and an optical multiplexer having an input optically coupled with light source device, an input that receives the signal beam, and an output that provides an excitation beam and signal beam to EDF. Semiconductor laser element has an active layer, provided between cladding layers and including compound semiconductors of mutually different conductivity types, that includes a compound semiconductor and is constructed such that the oscillation wavelength at 20° C. of this semiconductor laser element is less than 1470 nm but not less 1440 nm. If this is done, the change of gain in EDF with respect to oscillation wavelength can be made satisfactorily small and the NF can be made satisfactorily small.
    Type: Grant
    Filed: November 27, 2002
    Date of Patent: March 22, 2005
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Satoru Nakazawa, Yasunori Murakami
  • Patent number: 6862133
    Abstract: The present invention has an object to provide a Raman amplifier, a WDM optical communication system and a method of controlling the Raman amplification, capable of optimizing amplification characteristics in response to a change of operating conditions of the system so that transmission quality of the WDM signal light can be maintained in good.
    Type: Grant
    Filed: October 10, 2002
    Date of Patent: March 1, 2005
    Assignee: Fujitsu Limited
    Inventors: Miki Onaka, Yasushi Sugaya, Etsuko Hayashi
  • Patent number: 6856455
    Abstract: An apparatus has first and second light sources, a plurality of filters, and an optical switch. The light sources output a light beam having a spectrum determined by a gain band thereof. The plurality of filters each have a reflection band included in the gain band. The optical switch selectively couples the filters to the light source. The first and second light sources provide pumping light to a single transmission line. The first and second filters are configured so as to not reflect signal light to be amplified.
    Type: Grant
    Filed: August 8, 2002
    Date of Patent: February 15, 2005
    Assignee: Fujitsu Limited
    Inventors: Norihisa Naganuma, Norifumi Shukunami
  • Patent number: 6813066
    Abstract: An apparatus and method are described for exploiting almost the full almost 25TH% of bandwidth available in the low-loss window in optical fibers (from 1430 nm-1620 nm) using a parallel combination of optical amplifiers. The low-loss window at about 1530 nm-1620 nm can be amplified using erbium-doped fiber amplifiers (EDFAs). However, due to the inherent absorption of the erbium at shorter wavelengths, EDFAs cannot be used below about 1525 nm without a significant degradation in performance. For the low-loss window at approximately 1430-1530 nm, amplifiers based on nonlinear polarization in optical fibers can be used effectively. A broadband nonlinear polarization amplifier (NLPA) is disclosed which combines cascaded Raman amplification with parametric amplification or four-wave mixing. In particular, one of the intermediate cascade Raman order wavelengths &lgr;r should lie in close proximity to the zero-dispersion wavelength &lgr;0 of the amplifying fiber.
    Type: Grant
    Filed: July 1, 2002
    Date of Patent: November 2, 2004
    Assignee: The Regents of the University of Michigan
    Inventor: Mohammed Islam
  • Patent number: 6781747
    Abstract: The invention concerns a method for the amplification of wavelength division multiplex (WDM) signals in a WDM transmission system, pump light being injected into an optical waveguide of the optical transmission system contrary to the transmission direction of the WDM signals, the pump light being designed so that at least one WDM signal is individually amplified by a stimulated Brillouin scattering process in the optical waveguide produced by the pump light, as well as an optical amplifier, an optical broadband amplifier system and a WDM transmission system for it.
    Type: Grant
    Filed: May 29, 2002
    Date of Patent: August 24, 2004
    Assignee: Alcatel
    Inventor: Gustav Veith
  • Patent number: 6775057
    Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.
    Type: Grant
    Filed: April 11, 2002
    Date of Patent: August 10, 2004
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Youichi Akasaka, Yoshihiro Emori, Shu Namiki
  • Patent number: 6768577
    Abstract: A tunable multimode wavelength division multiplex Raman pump and amplifier, and a system, method, and computer program product for controlling a tunable Raman pump and amplifier. The tunability of the pump source is accomplished by either straining or heating an external fiber grating, thereby causing a different wavelength of light to be emitted by the pump source. The system includes a microprocessor-based controller that monitors an amplifier's performance and adjusts the drive current and/or wavelength of the tunable pumps of an amplifier to achieve a target performance.
    Type: Grant
    Filed: March 15, 2002
    Date of Patent: July 27, 2004
    Assignee: Fitel USA Corp.
    Inventors: Benjamin J. Eggleton, Paul Steinvurzel, Yoshihiro Emori, Shu Namiki, Akira Fujisaki, Toshio Kimura
  • Patent number: 6760152
    Abstract: The present application relates to a doped fiber amplifier having an increased dynamic range, and particularly for laser pump sources and a method of pumping erbium doped fiber amplifiers over a greater dynamic range. In a multi-channel optical system, optical amplifiers must be able to provide gain over a larger range of signal powers, the dynamic range corresponding to the number of channels in the link. The present invention has found that the dynamic range of an EDFA can be significantly increased by using pulse width modulation to pulse pump current at or near the minimum current stability threshold, in order to produce lower power output. The duty cycle of the pulsed current is selected to achieve a time-averaged operating condition taking advantage of the relatively long relaxation time of the erbium. Thus the time averaged pump power can be reduced in a linear fashion well below the capability of a continuous wave system.
    Type: Grant
    Filed: October 11, 2002
    Date of Patent: July 6, 2004
    Assignee: JDS Uniphase Corporation
    Inventors: Daniel Ratoff, Paul Nathan Freeman
  • Patent number: 6747788
    Abstract: The invention provides an optical fiber amplifier which assures stable operation of a pump light source and efficiently makes use of residual pump power to achieve improvement in conversion efficiency. The optical fiber amplifier includes a rare earth doped fiber. Pump light from a pump light source is introduced into one end of the rare earth doped fiber by way of a first optical coupler, and residual pump light originating from the pump light and arriving at the other end of the rare earth doped fiber is applied to the other rare earth doped fiber amplifier or the loss compensation of a dispersion compensating fiber by Raman amplification.
    Type: Grant
    Filed: September 20, 2001
    Date of Patent: June 8, 2004
    Assignee: Fujitsu Limited
    Inventor: Susumu Kinoshita
  • Patent number: 6744556
    Abstract: In a distributed Raman amplification system, the pump laser and the fiber are chosen so as to have characteristics which result in broadening of the DRBS. For example, with a transmission fiber through which signal light of a wavelength &lgr;s propagates, and having zero dispersion at a wavelength &lgr;o; a pump laser producing counterpropagating pump light at a wavelength &lgr;p; where &lgr;p and &lgr;s are on opposite sides of the zero dispersion wavelength is used. The transmission fiber may be large effective area fiber. In a Raman amplification system suitable for use in a WDM optical fiber communication system, pump lasers having mode spacing which is less than the optical bandwidth of the signal channel have been found to be advantageous.
    Type: Grant
    Filed: March 14, 2002
    Date of Patent: June 1, 2004
    Assignee: Corning Incorporated
    Inventors: Stuart Gray, Kim Jepsen, Michael Vasilyev
  • Patent number: 6731426
    Abstract: An L band optical amplifier in disclosed. The optical amplifier includes a signal line which has an input, an output disposed optically downstream of the input, and an amplifying gain medium optically disposed between the input and the output. The optical amplifier further includes a laser optically connected to the first amplifying gain medium and an apparatus for directing C band light into the amplifying gain medium.
    Type: Grant
    Filed: June 25, 2001
    Date of Patent: May 4, 2004
    Assignee: Photon-X, Inc.
    Inventors: Aydin Yeniay, Renyuan Gao
  • Patent number: 6714342
    Abstract: A Raman amplifier assembly includes a Raman amplifier configured to receive a signal from a signal source. The signal travels in an upstream direction in the Raman amplifier. A first pump source is coupled to the Raman amplifier. The first pump source produces a first pump beam that travels in a downstream direction and is counter-propagating relative to the signal. A second pump source is coupled to the Raman amplifier and produces a second pump beam that travels in the upstream direction. The second pump source has an average relative intensity noise of less than −80 dB/Hz.
    Type: Grant
    Filed: January 2, 2003
    Date of Patent: March 30, 2004
    Assignee: Xtera Communications, Inc.
    Inventors: Mohammed N. Islam, Michael Freeman
  • Patent number: 6654162
    Abstract: A Raman amplifier according to the present invention comprises a plurality of pumping means using semiconductor lasers of Fabry-Perot, DFB, or DBR type or MOPAs, and pumping lights outputted from the pumping means have different central wavelengths, and interval between the adjacent central wavelength is greater than 6 nm and smaller than 35 nm. An optical repeater according to the present invention comprises the above-mentioned Raman amplifier and adapted to compensate loss in an optical fiber transmission line by the Raman amplifier. In a Raman amplification method according to the present invention, the shorter the central wavelength of the pumping light the higher light power of said pumping light.
    Type: Grant
    Filed: June 22, 2001
    Date of Patent: November 25, 2003
    Assignee: The Furukawa Electric Co., Ltd.
    Inventors: Youichi Akasaka, Yoshihiro Emori, Shu Namiki