Including Polarization Patents (Class 398/152)
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Patent number: 7769302Abstract: The invention includes methods and apparatuses to adjust an optical signal transmitted through an optical amplifier, such as in a wavelength division multiplexed optical network. The methods and apparatus of the invention calculate polarization effects which cause degradation to the optical signal. A measurement of the polarization-related degradation of an optical signal is calculated by using at least one reference signal. In some embodiments of the invention, the reference signal is depolarized or has scrambled polarizations. The invention is typically used in long-haul optical networks.Type: GrantFiled: March 13, 2007Date of Patent: August 3, 2010Assignee: AT&T Intellectual Property II, L.P.Inventors: Martin Birk, Xiang Zhou
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Publication number: 20100189445Abstract: An optical receiver for receiving an optical signal that transmits a first data signal and a second data signal, including: an optical front-end configured to generate a digital signal that represents the optical signal; a detector configured to detect a state of the optical signal by using the digital signal and output state information that represents the state of the optical signal; a state controller configured to control the digital signal on the basis of the state information in order to recover the first data signal; and a data recovery configured to recover the second data signal on the basis of the state information.Type: ApplicationFiled: November 16, 2009Publication date: July 29, 2010Applicant: FUJITSU LIMITEDInventors: Hisao NAKASHIMA, Takeshi HOSHIDA
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Patent number: 7747169Abstract: A method for operating an optical receiver includes at each of a sequence of sampling times, producing a first 2D complex digital signal vector whose first component is indicative of a phase and amplitude of one polarization component of a modulated optical carrier and whose second component is indicative of a phase and amplitude of another polarization component of the carrier. For each one of the sampling times, the method includes constructing a second 2D complex digital signal vector that is a rotation of the first 2D complex digital vector for the one of sampling times. The rotation compensates a polarization rotation produced by transmission of the modulated optical carrier between an optical transmitter and the optical receiver.Type: GrantFiled: December 22, 2006Date of Patent: June 29, 2010Assignee: Alcatel-Lucent USA Inc.Inventor: Ut-Va Koc
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Publication number: 20100142970Abstract: Efficient apparatus, methods, systems and devices to generate, transmit and detect optical differential polarization-phase-shift keying signals are disclosed for high spectral efficiency optical communication systems. It includes an electrical encoder and an optical encoder for generation of differentially encoded polarization-phase modulated optical signals and optical demodulators and balanced detectors for detection of the optical signals. The optical signals are transmitted through optical fiber links or free space. The electrical encoder maps independent data channels into differentially-encoded data sequences. In the optical encoder, the encoded data sequences from the electrical encoder drive optical modulators to generate differentially-encoded polarization-phase modulated optical signals at a symbol rate equal to the bit rate of each input data channel.Type: ApplicationFiled: November 13, 2009Publication date: June 10, 2010Inventors: Yan Han, Guifang Li
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Patent number: 7724435Abstract: Devices and their operations to use multiple adjustable differential group delay (DGD) elements in various applications including tunable PMD emulators and compensators for producing different PMD profiles with an adjustable average DGD value.Type: GrantFiled: June 5, 2007Date of Patent: May 25, 2010Assignee: General Photonics CorporationInventors: Lianshan Yan, X. Steve Yao
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Patent number: 7725037Abstract: A method and apparatus for switching at least one wavelength component of an optical signal beam from a first state to a second state. The phase characterizing the optical signal component is incremented by interaction with one or more escort beams in a non-linear medium thereby switching the state of the optical signal component on the basis of its incremented phase. Multiple escort beams may also be employed to switch different wavelength components of the signal. The method may be employed to achieve high speed, and substantially transparent, switching of phase, intensity or polarization of a signal.Type: GrantFiled: November 13, 2006Date of Patent: May 25, 2010Assignee: The Board of Trustees of the University of IllinoisInventors: Aaron Pace VanDevender, Paul G. Kwiat
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Patent number: 7715730Abstract: The polarization-multiplexed signal contains two data signals that are orthogonally polarized in relation to one another. Their carrier signals are derived from the same source and thus have the same wavelength. The phase difference between the carrier signals, is adjusted or regulated in such a way that it corresponds to 90°. The phase difference of the carrier signals permits the susceptibility to polarization mode dispersion to be significantly reduced.Type: GrantFiled: January 27, 2005Date of Patent: May 11, 2010Assignee: Nokia Siemens Networks GmbH & Co. KGInventors: Nancy Hecker, Dirk van den Borne
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Generation of Quantum-Correlated and/or Polarization Entangled Photon Pairs with Unequal Wavelengths
Publication number: 20100111541Abstract: The invention provides an apparatus and method for generating quantum-correlated and/or polarization-entangled photon pairs with unequal wavelengths. The photon pairs generated collinearly with respect to the pump light via a nonlinear process in a nonlinear optical medium are collected into a single mode fiber and split using a dichroic device. The wavelengths of photons constituting a pair are selected such that, first, their efficient propagation in the same single mode optical fibre, and second, their efficient splitting with high switching ratio, is possible. A detected rate ˜105-106 pairs/s and >98% quantum interference visibility of polarization entanglement is observed. This source, given its performance, robustness and minimum alignment requirements is ideal for quantum communication schemes, in particular for entanglement-based quantum cryptography.Type: ApplicationFiled: March 6, 2008Publication date: May 6, 2010Inventors: Pavel Trojek, Harald Weinfurter -
Publication number: 20100111531Abstract: An optical transmission/reception system includes a modulator for modulating light based on data to output signal light; a transmission-side signal processor performing transmission-side digital signal processing which imparts a polarization change to the signal light by the optical modulation with respect to an input signal; an optical transmitter in which the modulator performs the optical modulation based on the input signal subjected to the transmission-side digital signal processing in the transmission-side signal processor; and an optical receiver including a converter converting the signal light inputted from the optical transmitter via a transmission path to a digital electric signal for each polarization component, and a reception-side signal processor performing reception-side digital signal processing which imparts a polarization change having a property substantially inverse to a property of the polarization change in the transmission-side signal processor with respect to the digital electric signType: ApplicationFiled: October 19, 2009Publication date: May 6, 2010Applicant: FUJITSU LIMITEDInventors: Takahito Tanimura, Takeshi Hoshida, Hisao Nakashima
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Patent number: 7706694Abstract: A system for and method of processing complex signals encoded into quantum states is presented. According to an embodiment of the invention, polarized components of a pump laser beam are separated and respectively modulated with first and second signals. The modulated polarized components are directed to adjacent non-linear crystals with optical axes aligned at right angles to each-other. Information regarding at least one of the first and second signals is then derived from measurements of coincidence events.Type: GrantFiled: July 25, 2006Date of Patent: April 27, 2010Assignee: General Dynamics Advanced Information Systems, Inc.Inventor: Richard Freeling
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Publication number: 20100092176Abstract: To provide a polarization-diverse, heterodyne optical receiving system, a light signal is transmitted into an optical fiber having a plurality of optical sensors that are distinguishable using a multiplexing arrangement. A return light signal from the optical fiber is mixed with an optical local oscillator light signal, where the mixing outputs plural output signal portions having different polarizations. A birefringence of a particular optical sensor is determined based on the plural signal portions.Type: ApplicationFiled: October 14, 2009Publication date: April 15, 2010Applicant: SCHLUMBERGER TECHNOLOGY CORPORATIONInventors: Arthur H. Hartog, Dominic Brady, Maxwell R. Hadley
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Patent number: 7697848Abstract: A wireless communication system, a wireless transmitting apparatus, and a wireless receiving apparatus which can be applied to all types of light sources and can be applied to a variety of fields, provided with a medium forming an information transmission source, a general light source made of for example a lamp or the sun or another natural light source or artificial light source, a wireless transmitting apparatus for making the polarization of the light from the light source uniform and controlling the polarization plane of an infrared ray, visible ray, UV ray, or other light (modulating the light in polarization) so as to superimpose other information invisible to the human eye on visual information due to general reflected light and transmitting the same as an optical wireless signal, and a wireless receiving apparatus for receiving the optical wireless signal transmitted from the wireless transmitting apparatus and able to determine a change in orientation of the polarization plane of the light as informType: GrantFiled: May 30, 2006Date of Patent: April 13, 2010Assignee: Kyocera CorporationInventors: Tohru Sunaga, Yasuyuki Irie
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Publication number: 20100080569Abstract: A method and an apparatus for generating a differential quadrature phase shift keying (DQPSK) code optical signal are provided. The method may includes splitting an optical signal to obtain two polarized optical signals, modulating and phase-shifting one of the two polarized optical signals to obtain a phase-shifted and polarized optical signal, and modulating the other of the two polarized optical signals to obtain another polarized and modulated optical signal. The phase-shifted and polarized optical signal may be combined with the other polarized and modulated optical signal to obtain a polarization multiplexed optical signal. The method may further include, polarizing the polarization multiplexed optical signal to obtain the DQPSK code optical signal. The apparatus may include a polarization beam splitter (PBS), modulators, a phase-shift controller, a polarization beam combiner (PBC), and a polarizer.Type: ApplicationFiled: December 1, 2009Publication date: April 1, 2010Inventors: Xiaogeng XU, Chao LV
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Patent number: 7684701Abstract: A photon emitter including a photon generator configured to generate photons having a first polarization state or a second polarization state, the first polarization state being orthogonal to the second polarization state; and a time delay device which delays photons having the second polarization state with respect to those having the first polarization state.Type: GrantFiled: February 26, 2004Date of Patent: March 23, 2010Assignee: Kabushiki Kaisha ToshibaInventors: Zhiliang Yuan, Andrew James Shields
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Publication number: 20100054753Abstract: An apparatus includes: a polarizing beam splitter for splitting the input light into a first light and a second light and for outputting the first light and the second light into optical paths, respectively; a polarization rotator rotating polarized light of the light path by approximately 90 degree; a first path length adjuster adjusting a difference path length between the optical paths in order to be approximately equal to zero; a second path length adjuster adjusting a difference path length between the optical paths in order to be an integer multiple of a wavelength of the input light; an optical attenuator arranged adjusting a propagation loss of the optical path in order to approximately match the propagation losses of the optical paths; and an output element for combining the first light and the second light from the paths and for outputting the output light.Type: ApplicationFiled: August 21, 2009Publication date: March 4, 2010Applicant: Fujitsu LimitedInventors: Fumio FUTAMI, Shigeki Watanabe
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Patent number: 7672589Abstract: Method for reducing signal degradation in an optical polarisation-multiplex system. The modulated optical signals to be transmitted are synchronised or generated such that the phase difference for NRZ-modulated signals is at least approximately 0° and the phase difference for RZ-modulated signals is at least approximately 180°. They can also be achieved by means of different synchronising devices.Type: GrantFiled: May 6, 2003Date of Patent: March 2, 2010Assignee: Nokia Siemens Network GmbH & Co., KGInventors: Erich Gottwald, Nancy Hecker, Werner Paetsch, Wolfgang Schairer
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Patent number: 7668468Abstract: The present invention relates to a numerous user laser communications optical system. Numerous optical signals comprising a number of channels are simultaneously received and demultiplexed (and/or multiplexed and transmitted) at a numerous access communication device. The numerous access communication device may comprise multiple stages that each include a multiple order waveplate and a polarizing beam splitter. The multiple order waveplate is configured so that it retards a first electrical field component of signals corresponding to certain channels in a frequency grid in an integer multiple of wavelengths with respect to a second electrical field component, and retards a first electrical field component of signals corresponding to other channels in the frequency grid in an integer multiple of wavelengths plus one-half a wavelength with respect to a second electrical field component. Separation can then be performed on the basis of the resulting opposite polarization.Type: GrantFiled: September 28, 2005Date of Patent: February 23, 2010Assignee: Ball Aerospace & Technologies Corp.Inventors: Isabella T. Lewis, Robert W. Kaliski
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Publication number: 20100034541Abstract: A feedback signal indicative of the average RF power of an APol-DPSK optical signal is used by a PMD compensator to adjust the amount of compensation applied to the optical signal.Type: ApplicationFiled: August 5, 2008Publication date: February 11, 2010Applicant: LUCENT TECHNOLOGIES INC.Inventor: Chongjin XIE
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Patent number: 7660533Abstract: A method of data compression and transmission include splitting a wave function representative of an input data set into an arbitrarily oriented elliptical polarization state and a comparator wave function state, the comparator wave function state being transmitted to a detector. A quantum Fourier transform is performed on the arbitrarily oriented elliptical polarization state to yield a quantum computational product. A quantum Hadamard transform is performed on the quantum computational product to yield one of two possible quantum particle outputs. The input data set is reconstructed based upon the coincident arrival of the comparator wave function state and one of the two quantum particle outputs. A method is performed on either a quantum computer or a digital computer. An optical bench with appropriate electronics is particularly well suited to function as a quantum computer for the compression and transmission of data corresponding to sound.Type: GrantFiled: August 4, 2005Date of Patent: February 9, 2010Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Ronald E. Meyers, Keith S. Deacon
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Publication number: 20100021178Abstract: A switch is to be inputted a modulation signal including the synchronization signal extracted from a received communication signal as a control signal, is to be inputted a detection signal detected by a photodetector that receives a polarization modulation signal adjusted to a polarization direction of a quantum cipher signal, and selectively switches and outputs one of the detection signal and an inverted signal of the detection signal according to the control signal. A low-pass filter outputs the output signal of the switch, whereby a plus level signal is outputted when a relative angle difference ?? between polarization axes on a transmission side and a reception side is larger than a predetermined polarization angle, a 0 level signal is outputted when ?? is equal to the predetermined polarization angle, and a minus level signal is outputted when ?? is in a range of the predetermined polarization angle from 0 degree.Type: ApplicationFiled: July 21, 2009Publication date: January 28, 2010Applicant: NATIONAL INSTITUTE OF INFORMATION AND COMMUNICATIONS TECHNOLOGYInventor: Morio Toyoshima
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Patent number: 7646983Abstract: An apparatus and method directed to testing and optimizing performance of an optical transmission system is disclosed, including at least one broadband dispersion compensation unit (DCU) or at least one depolarization device. The depolarization device may be used alone or in combination with the at least one broadband DCU. A method for optimizing performance of data channels in initial loading (IL) and full loading (FL) configurations of the optical transmission system is also disclosed.Type: GrantFiled: March 10, 2009Date of Patent: January 12, 2010Assignee: Tyco Telecommunications (US) Inc.Inventors: Michael Vaa, Franklin W. Kerfoot, III, Georg H. Mohs, Ekaterina A. Golovchenko, Robert L. Lynch, Stuart M. Abbott, Howard D. Kidorf, Bamdad Bakhshi
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Publication number: 20100003034Abstract: The present invention describes methods and apparatus for adaptive polarization transmission. An exemplary embodiment of the present invention provides an adaptive polarization transmission method. The method includes the step of analyzing at a transmitter device a first set of polarization state information relating to a first wireless signal path. Furthermore, the method includes the step of adapting a transmission signal to be distributed by the transmitter device based on at least the first set of polarization state information. In addition to adaptive polarization transmission methods, the present invention provides various adaptive polarization transmission systems. In an exemplary embodiment, an adaptive polarization transmission system includes a transmitter device. The transmitter device includes an analyzing unit for processing a first set of polarization state information relating to a first wireless signal path.Type: ApplicationFiled: January 30, 2008Publication date: January 7, 2010Applicant: Georgia Tech Research CorporationInventors: Thomas G. Pratt, Brett T. Walkenhorst
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Patent number: 7643760Abstract: Efficient apparatus, methods, systems and devices to generate, transmit and detect optical differential polarization-phase-shift keying signals are disclosed for high spectral efficiency optical communication systems. It includes an electrical encoder and an optical encoder for generation of differentially encoded polarization-phase modulated optical signals and optical demodulators and balanced detectors for detection of the optical signals. The optical signals are transmitted through optical fiber links or free space. The electrical encoder maps independent data channels into differentially-encoded data sequences. In the optical encoder, the encoded data sequences from the electrical encoder drive optical modulators to generate differentially-encoded polarization-phase modulated optical signals at a symbol rate equal to the bit rate of each input data channel.Type: GrantFiled: March 3, 2006Date of Patent: January 5, 2010Assignee: University of Central Florida Research Foundation, Inc.Inventors: Yan Han, Guifang Li
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Patent number: 7639945Abstract: In an optical switch device, an optical control pulse is inputted into a nonlinear optical fiber in phase with each optical pulse of signal light which is to be outputted, so that the polarization directions of the optical control pulse and the signal light form a predetermined angle at the input stage of the nonlinear optical fiber, the optical control pulse causes polarization rotation and parametric amplification of the optical pulse in the nonlinear optical fiber, and then the optical pulse is outputted through a polarizer. The excitation level of the optical control pulse is set on the basis of the difference of a monitored output level of the optical pulse from a target level so that the output levels of optical pulses of the signal light are controlled at one or more desired levels.Type: GrantFiled: February 3, 2006Date of Patent: December 29, 2009Assignee: Fujitsu LimitedInventors: Yuji Tamura, Shigeki Watanabe
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Patent number: 7639953Abstract: Various embodiments of the present invention are directed to compact systems for generating polarization-entangled photons. In one embodiment of the present invention, a non-degenerate, polarization-entangled photon source comprises a half-wave plate that outputs both a first pump beam and a second pump beam, and a first beam displacer that directs the first pump beam into a first transmission channel and the second pump beam into a second transmission channel. A down-conversion device converts the first pump beam into first signal and idler photons and converts the second pump beam into second signal and idler photons. A second beam displacer directs both the first signal and idler photons and the second signal and idler photons into a single transmission channel. A dichroic mirror directs the first and second signal photons to a first fiber optic coupler and the first and second idler photons to a second fiber optic coupler.Type: GrantFiled: July 27, 2006Date of Patent: December 29, 2009Assignee: Hewlett-Packard Development Company, L.P.Inventors: Sean Spillane, Charles Santori, Marco Fiorentino, Raymond G. Beausoliel
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Publication number: 20090304392Abstract: Provided is a reflective optical circulator capable of improving characteristics by preventing the occurrence of PDL and non-uniformity of insertion losses of reciprocating optical paths. The reflective optical circulator includes: an optical element unit having a first polarization separating element, a 45° non-reciprocal polarization plane rotating element, a phase element for rotating a polarization plane of an incident light by 90°, and a second polarization separating element; a light incidence/emission unit; a lens; and a reflector. All waveguides are disposed at an equivalent distance from a central point, and a shift amount of an extraordinary ray in the second polarization separating element is set to be larger than a shift amount of an extraordinary ray in the first polarization separating element. In addition, the phase element is constructed with two phase optical elements, and only one polarization component is allowed to transmit through the two phase optical elements.Type: ApplicationFiled: March 8, 2007Publication date: December 10, 2009Applicant: NAMIKI SEIMITSU HOUSEKI KABUSHIKI KAISHAInventors: Yoshihiro Konno, Masaru Sasaki
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Patent number: 7627251Abstract: A communication device uses one or two stacks of reflective deflectors to steer the electromagnetic waves carrying signals received and transmitted through a single telescope/aperture device. The signals outside the device may be circularly polarized while inside the device they are linearly polarized most of the time. The deflectors within each stack are transparent to the signals steered by the deflectors behind them. Since the deflecting wave band may shift with the changing angle of incidence of the signals due to steering, the wave bands are sufficiently spaced apart. When the signals impact the deflectors at nearly normal angles, the wave bands can be made more narrow. When more than one stack of deflectors is used, the spacing between the wave bands within one stack may be utilized by another stack.Type: GrantFiled: June 24, 2003Date of Patent: December 1, 2009Assignee: Massachusetts Institute of TechnologyInventors: Frederick G. Walther, Jeffrey M. Roth, William E. Keicher, Alan E. DeCew
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Publication number: 20090290882Abstract: Signal light, pumping light and control light having different wavelengths are input to a nonlinear optical medium. The power of the pumping light is controlled to generate a desired gain in the nonlinear optical medium. The power of the control light is controlled to saturate the gain of the nonlinear optical medium.Type: ApplicationFiled: January 30, 2009Publication date: November 26, 2009Applicant: FUJITSU LIMITEDInventor: Shigeki WATANABE
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Publication number: 20090285583Abstract: An optical communication system may include a light transmission unit transmitting a light beam having a first polarization, a quarter waveplate to receive the light beam and to modify the light beam to have a second polarization, and a retroreflector to receive the light beam from the quarter waveplate and reflect the light beam to the quarter waveplate, which modifies the light beam to have a third polarization. The optical communication system may also include a half waveplate to modify the first polarization such that the first polarization is about 90 degrees rotated compared to the third polarization, and a polarizer to pass the light beam having the third polarization and to block most of the light beam having the first polarization.Type: ApplicationFiled: May 15, 2008Publication date: November 19, 2009Inventors: Bruce K. Winker, Bing Wen, Jian Ma
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Patent number: 7620326Abstract: The invention relates to a method for transmitting at least one first and second data signal in polarization multiplex. To this end, the invention provides that, in a first step, the first data signal is, on the transmit side, modulated to a sideband of a first carrier signal for generating a first sideband-modulated signal, and the second data signal is modulated to a sideband of a second carrier signal in order to generate a second sideband-modulated signal. In a second step, the first and second sideband-modulated signal are subsequently polarized orthogonal to one another, combined to form an optical multiplex signal and transmitted. In a third step, the optical multiplex signal is, on the receive side, guided via a polarization control element to a polarization splitter that separates the transmitted optical multiplex signal into the first and second sideband-modulated signal.Type: GrantFiled: July 7, 2003Date of Patent: November 17, 2009Assignee: Nokia Siemens Networks GmbH & Co KGInventor: Christoph Glingener
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Publication number: 20090279900Abstract: The present invention provides systems and methods for the mitigation of PMD impairments in fiber optic links. The present invention utilizes synchronous polarization modulation and digital control of polarization modulation, instead of independent polarization modulators and analog control used in the current state of art. Also, the present invention utilizes a feedback loop to avoid identified bad polarization states instead of a random open loop operation. Further, the present invention includes a mechanism to continually update polarization states based on pre-corrected FEC error analysis from data receivers. Additionally, the present invention includes a mechanism for collecting and correlating error feedback signals from multiple geographically-diverse network nodes. Advantageously, the present invention provides a cost-effective and efficient way to implement mitigation of PMD impairments, while using only a small fraction of the FEC error correction capability.Type: ApplicationFiled: May 6, 2008Publication date: November 12, 2009Inventor: Michael Y. Frankel
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Patent number: 7616898Abstract: A method of operating an optical transmission system is described. The transmission system is provided with a bit-to-bit polarization interleaved bitstream having a given bitrate. The transmission system comprises a birefringent element and/or a decision circuit. The birefringent element and/or the decision circuit are triggered by a trigger signal having a frequency of half of the bitrate.Type: GrantFiled: March 29, 2005Date of Patent: November 10, 2009Assignee: AlcatelInventors: Gabriel Charlet, Erwan Corbel
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Patent number: 7616900Abstract: By comprising a unit 2 making the adjustment related to degradation compensation of a plurality of signals with each wavelength made after multiplexing the signals, a unit 3 multiplexing the outputs of a plurality of units 2, a unit 4 compensating for the waveform degradation of the output of the unit 3, a unit 5 selecting a component with one of a plurality of wavelengths from a part of the output of the unit 4 and a unit 6 detecting the degree of signal degradation from the output of the unit 5 and controlling the adjustment by the unit 2 corresponding to the selected frequency so as to reduce the degree, components disposed for each wavelength in an optical transmission system adopting a wavelength-division multiplexing method can be shared, and the size and cost of an compensator can be reduced.Type: GrantFiled: July 26, 2004Date of Patent: November 10, 2009Assignee: Fujitsu LimitedInventors: Akihiko Isomura, Jens C. Rasmussen, George Ishikawa
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Publication number: 20090274464Abstract: A method, a system, and a device for setting up a wavelength connection are disclosed herein. The method includes obtaining a wavelength path from a source network node to a destination network node and wavelength impairment compensation information of the wavelength path; and setting up the wavelength connection from the source network node to the destination network node according to the wavelength path and performing impairment compensation for wavelength signals in an interface of each network node on the wavelength path according to the wavelength impairment compensation information during setting up the wavelength connection. The device disclosed herein includes a path calculation server, a network node device, and a control server. The system disclosed herein is a network communication system. The embodiments of the present disclosure set up an available wavelength connection efficiently, simply and quickly.Type: ApplicationFiled: July 13, 2009Publication date: November 5, 2009Inventors: Xiaobing Zi, Huiying Xu, Shuqiang Shen
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Publication number: 20090274469Abstract: In a polarization multiplexed optical transmitting and receiving apparatus, output light from a light source section of a transmission unit is separated in a polarization separating section, and then modulated in first and second modulation sections, and the modulated lights are synthesized in a polarization synthesizing section, and transmitted to an optical transmission line. Then the polarization multiplexed light propagated through the optical transmission line is demodulated in a reception section of a reception unit, and together with this, transmission characteristic information of the reception light is transferred to the transmission unit. The transmission unit that receives the transmission characteristics information controls a delay section that adjusts a delay amount of relative phases of drive signals of the modulation sections, so that the transmission characteristics of the polarization multiplexed light are within an allowable range.Type: ApplicationFiled: December 29, 2008Publication date: November 5, 2009Applicant: FUJITSU LIMITEDInventors: Masahiro Yuki, Kentaro Nakamura, George Ishikawa
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Patent number: 7609976Abstract: A method and system for ultra-high bit rate fiber-optic communications (e.g., 160 Gb/s) utilize a phase-correlated modulation format where phases of bits in adjacent four-bit groups in transmitted optical pulse trains are altered by ? (or 180°).Type: GrantFiled: September 29, 2005Date of Patent: October 27, 2009Assignee: Alcatel-Lucent USA Inc.Inventors: Xiang Liu, Lothar Benedict Erhard Josef Moeller, Yikai Su, Chongjin Xie
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Patent number: 7606498Abstract: A method of carrier recovery from a high speed optical signal received through an optical communications network. A stream of multi-bit digital samples of the optical signal is processed to generate a multi-bit estimate X?(n) of each one of a plurality of transmitted symbols. A phase of each symbol estimate X?(n) is rotated, and a respective symbol phase error ??(n) of the rotated symbol estimate determined.Type: GrantFiled: March 3, 2006Date of Patent: October 20, 2009Assignee: Nortel Networks LimitedInventors: Kuang Tsan Wu, Han Sun, Kim B. Roberts, Ruibin Jin, James Harley
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Patent number: 7603044Abstract: A system and method are provided for calibrating orthogonal polarity in a multichannel optical transport network (OTN) receiver. The method accepts a composite signal and separates the polarization of the signal into a pair of 2n-phase shift keying (2n-PSK) modulated input signals via Ix and Qx optical signal paths, where n?1. Likewise, a pair of 2p-PSK modulated input signals are accepted via Iy and Qy optical signal paths where p?1. Polarization-adjusted I?x, Q?x, I?y, and Q?y signals are generated. An average magnitude is compared to either 2×the absolute magnitude of (I?x and Q?x), or 2×the absolute magnitude of (I?y and Q?y). The average magnitude value can be used that is either 2×(a predetermined peak signal amplitude), or the sum of the absolute magnitudes of (I?x and Q?x) and (I?y and Q?y). The polarization-adjusted I?x, Q?x, I?y, and Q?y signals are modified until the magnitude comparison is about zero.Type: GrantFiled: December 3, 2008Date of Patent: October 13, 2009Assignee: Applied Micro Circuits CorporationInventors: Keith Conroy, Omer Acikel
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Patent number: 7596323Abstract: A method and apparatus for estimating fiber dispersion in an optical communication system including transmitting an optical signal carrying a unique word along an optical communication path, receiving the optical signal carrying the unique word from the optical communication path, producing an electrical signal corresponding to the received unique word, and processing the electrical signal corresponding to the received unique word to produce an estimate of the fiber dispersion in the optical communication system.Type: GrantFiled: January 4, 2006Date of Patent: September 29, 2009Assignee: Broadwing CorporationInventors: Alistair J. Price, Bassel F. Beidas, Terry L. Bittner, A. Roger Hammons, Jr., William M. Kirschner, Daniel F. McAlister, Shou Y. Mui
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Publication number: 20090238579Abstract: An optical receiver utilizes differential quadrature phase-shift keying (DQPSK) demodulation and electrical crosstalk rejection to relax requirements on filter misalignment with a carrier signal and to enable electronic polarization demultiplexing of optical signals. The optical receiver uses additional polarization state information when performing differential phase measurements on the optical signals. This provides information that ensures that data can be recovered by the optical receiver regardless of the state of polarization introduced during transmission of the optical signals. The optical receiver over samples the optical signals, which enables electrical polarization demultiplexing of the optical signals. The electrical crosstalk rejection provides a tracking algorithm that isolates received optical signals, and reduces crosstalk between data sequences.Type: ApplicationFiled: March 20, 2008Publication date: September 24, 2009Inventors: Jeffrey Thomas Rahn, Wei Chen
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Patent number: 7590355Abstract: A scheme is described for mitigating the effects of polarization-mode dispersion (PMD) in a wave-division multiplex (WDM) optical communication system having one or more transmission links with one or more quasi-static waveguide sections coupled by one or more non-static coupling sections. A transmitter is coupled to the transmission link and is adapted to transmit optical signals through the transmission link with wavelength channel spacing of the optical signals greater than about the PMD correlation bandwidth of at least one of the one or more quasi-static waveguide sections, so that the PMD induced outage probability for the system is optimized.Type: GrantFiled: February 28, 2006Date of Patent: September 15, 2009Assignee: Alcatel-Lucent USA Inc.Inventors: Robert Jopson, Herwig Kogelnik, Peter Winzer
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Patent number: 7587142Abstract: A method and system for estimating a fraction of an optical transmission system's transmission window that is compliant with the system's polarization mode dispersion (PMD) outage specifications, the optical transmission system including Ns optical fiber segments. The method comprises the steps of: propagating a plurality of optical signals through the Ns optical fiber segments; monitoring the differential group delay (DGD) for each optical signal over time; computing a time average and variance of the monitored DGD for each optical signal; computing statistics of the time averages and variances of the monitored DGD for each optical signal; determining the number of effective PMD sections and effective hinges in the system from the statistics; and determining the size of a PMD capacity compliant fraction for a specified outage probability.Type: GrantFiled: December 29, 2005Date of Patent: September 8, 2009Assignee: AT&T Intellectual Property II, LPInventors: Mikhail Brodsky, Mikhail Boroditsky, Nicholas Frigo, Peter David Magill
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Patent number: 7583895Abstract: A polarization scrambler has a polarization state rotating unit rotating the polarization state of a signal light, and a rotation speed controlling unit controlling the rotation speed of the polarization state in the polarization state rotating unit on the basis of the speed and scheme of modulation of the signal light, and the value of polarization mode dispersion of a transmission path on which the signal light is to be transmitted. Degradation of the transmission quality due to PMD is more mitigated than the known techniques.Type: GrantFiled: September 8, 2006Date of Patent: September 1, 2009Assignee: Fujitsu LimitedInventors: Kentaro Nakamura, Masahiro Yuki, Takeshi Hoshida, George Ishikawa
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Patent number: 7583896Abstract: An optical transmitter of an optical-wireless hybrid transmission system according to the invention outputs a first single-mode optical signal (center frequency: fC1) to an optical receiver, generates a polarization-coupled optical signal by orthogonal-polarization-coupling a second single-mode optical signal (center frequency: fC2) with a third single-mode optical signal (center frequency: fC3) so as to give the two waves orthogonal polarization directions and the same optical power, and transmits the generated polarization-coupled optical signal to a base station as an optical carrier signal. The optical receiver couples a modulated optical signal transmitted from the base station with the optical signal output from the optical transmitter, demodulates an electrical signal having intermediate frequencies fIF1 and fIF2 that is obtained by photodecting a resulting coupled optical signal, and generates transmit-data by filtering a resulting output signal.Type: GrantFiled: June 24, 2005Date of Patent: September 1, 2009Assignee: Nippon Telegraph and Telephone CorporationInventors: Tomohiro Taniguchi, Naoya Sakurai
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Patent number: 7577357Abstract: The present invention provides an optical switch in which a switching operation is not affected even when the polarization state of a control light varies. The optical switch comprises a loop-form optical waveguide loop circuit formed from an optical nonlinear medium, control light input means of phase control means for inputting the control light into the optical waveguide loop circuit, and a wavelength demultiplexing/multiplexing circuit. The optical waveguide loop circuit is constituted by an optical path formed from a first optical fiber extending from an optical demultiplexer/multiplexer to the control light input means, an optical path formed from a second optical fiber extending from the control light input means to the wavelength demultiplexing/multiplexing circuit, and an optical path formed from a fourth optical fiber extending from the wavelength demultiplexing/multiplexing circuit and returning to the optical demultiplexer/multiplexer.Type: GrantFiled: July 26, 2005Date of Patent: August 18, 2009Assignee: Oki Electric Industry Co., Ltd.Inventor: Shin Arahira
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Patent number: 7570419Abstract: In one embodiment of the present invention, a quantum entangled photon-pair producing device is disclosed which includes a superposed state generating device for generating a superposed state of photon-pairs entering through N (N?2) different incident optical paths and being composed of photons having different polarization directions, and a light-guide device for separating the photon-pairs entering through the N (e.g. N is two) incident optical paths into photons having a first polarization direction (e.g. horizontally polarized light) and those having a second polarization direction (e.g. vertically polarized light) and guiding the photons having the first polarization direction and entering through the i-th (1?i?N) (e.g. the first) incident optical path and photons having the second polarization direction and entering through the (N?i+1) (e.g. the second) incident optical path to the i-th (e.g. the first) exit optical path through optical paths having the same optical path length.Type: GrantFiled: March 1, 2007Date of Patent: August 4, 2009Assignee: Japan Science and Technology AgencyInventors: Keiichi Edamatsu, Ryosuke Shimizu
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Publication number: 20090190930Abstract: In an optical transmission system including a transmitter Tx and a receiver Rx connected via a fiber link F, where the receiver Rx is adapted to utilize Forward Error Correction (FEC) on received signals, a polarization scrambler is provided at the transmitter Tx to scramble the polarization state of a transmitted signal, a polarization delay line is provided at the receiver Rx for controlling the polarization mode dispersion induced distortion of a received signal, a feedback unit is provided at the receiver Rx for providing a feedback signal based on at least part of the received signal, and at least one polarization controller interconnects the fiber link F and the polarization delay line. The power controller is operable based on the feedback signal to mitigate the polarization mode dispersion of the signal.Type: ApplicationFiled: November 8, 2006Publication date: July 30, 2009Inventor: Jean Pierre Von Der Weid
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Patent number: 7565037Abstract: The present invention provides a method for reducing spreading of a pulse in a transmission line, said spreading being as a result of polarization mode dispersion, comprising inducing predetermined polarization rotations of particle or wave components of the pulse in the transmission line.Type: GrantFiled: August 12, 2005Date of Patent: July 21, 2009Assignees: Universite Libre de Bruxelles, University of BristolInventors: Sandu Popescu, Serge Alexandre Massar
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Patent number: 7554885Abstract: At least two light beams with polarization diversity are generated that each carry a representation of the same information. Separate optic fibers carry each of the at least two beams through a region subject to vibration to a remote location where the information is recovered by an optical receiver based on the separate light beams. Using separate fibers to carry polarization diverse information minimizes polarization noise at the optical receiver due to vibration of the fibers.Type: GrantFiled: February 22, 2005Date of Patent: June 30, 2009Assignee: Northrop Grumman Guidance and Electronics Company, Inc.Inventors: David B. Hall, Paul L. Greene
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Patent number: 7555221Abstract: A method and apparatus for polarization-independent RF spectrum analysis of an optical source, the apparatus including a coupler for coupling the light from an optical source under test with light from a continuous-wave (CW) laser. A nonlinear apparatus is coupled to the coupler for modulating the electric field of the light from the CW laser using the temporal intensity of the light from the source under test to generate a modulated signal. The nonlinear apparatus is adapted to mitigate or compensate for any phase difference between polarization components of signals propagated through the nonlinear apparatus. A polarizer is coupled to the nonlinear apparatus for generating a linearly polarized signal from the modulated signal. An optical spectrum analyzer is coupled to the polarizer for measuring the optical spectrum of the linearly polarized signal to determine an RF spectrum of the optical source under test.Type: GrantFiled: December 23, 2004Date of Patent: June 30, 2009Assignee: Alcatel-Lucent USA Inc.Inventor: Christophe J Dorrer