Dispersion Compensation Patents (Class 398/147)
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Patent number: 7274879Abstract: A control system for use in compensating for temperature-induced dispersion drift of an optical path, comprising an input adapted to obtain temperature data associated with the optical path; a control module adapted to determine control information on the basis of the temperature data; and an output adapted to provide a control signal to a dispersion compensator. The control signal is determined such that its receipt by the dispersion compensator causes the latter to induce a dispersive effect in a signal that travels the optical path, the dispersive effect being related to the control information. The ability to compensate for temperature-induced dispersion drift reduces the distortion margin in optical link budgets, allowing optical links to have longer reach, or to achieve the same reach using fewer line amplifiers. In a specific embodiment, dispersion compensation is accomplished via an open-loop control system such that feedback from the receiver site is not required.Type: GrantFiled: October 23, 2003Date of Patent: September 25, 2007Assignee: Nortel Networks LimitedInventors: Howard Martin Sandler, Maurice O'Sullivan
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Patent number: 7272286Abstract: The invention relates to the field of dispersion managed optical fibres for use in wavelength division multiplex transmission networks. A multimode optical fibre in which at least one higher-order mode can be propagated, is constituted radially by a single central core surrounded by an optical cladding (13), and comprises, for said higher mode or for at least one of said higher-order modes, positive chromatic dispersion optical fibre portions (D+) alternating longitudinally with negative chromatic dispersion optical fibre portions (D?).Type: GrantFiled: December 22, 2004Date of Patent: September 18, 2007Assignee: Draka Comteq B.V.Inventors: Lionel Provost, Isabelle Bongrand, Carlos De Barros
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Patent number: 7269358Abstract: An optical transmitter for an optical fiber transmission system is described. The optical transmitter includes an optical source that generates an optical signal having a wavelength at an output. An optical intensity modulator modulates the optical signal with an electrical modulation signal to generate a modulated optical signal at an output. At least one parameter of the optical intensity modulator is chosen to suppress at least one of phase and sideband information in the modulated optical signal. An optical fiber is coupled to the output of the optical intensity modulator. The suppression of the at least one of the phase and the sideband information in the modulated optical signal increases an effective modal bandwidth of the optical fiber.Type: GrantFiled: September 9, 2003Date of Patent: September 11, 2007Assignee: Optium CorporationInventors: Peter Hallemeier, Mark Colyar, Eitan Gertal, Heider Ereifej
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Patent number: 7266257Abstract: An optical transmitter includes a modulator, a dispersion adjustment module, and an optical amplifier. The optical transmitter is configured to transmit optical pulses over a free-space optical communication channel. The modulator is configured to produce an optical carrier that is amplitude and/or phase modulated by data. The dispersion adjustment module is connected between the modulator and the amplifier and is configured to substantially change temporal widths of optical pulses received from the modulator by changing dispersions of the received optical pulses.Type: GrantFiled: July 12, 2006Date of Patent: September 4, 2007Assignee: Lucent Technologies Inc.Inventors: Aref Chowdhury, Gregory Raybon
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Patent number: 7263296Abstract: In a system connecting a transmitter and a receiver using transmission paths and repeaters (in-line amplifiers), red chirping whose ? parameter is performed for an optical signal on a transmitting side. Each of the repeaters includes a dispersion-compensator for compensating the amount of dispersion on a preceding transmission path. The amount of dispersion compensation of the dispersion-compensator included in the transmitter is made constant. The dispersion-compensator included in the receiver is arranged in order to compensate the amount of dispersion on a preceding transmission path. A spread of a pulse width on a transmission path can be efficiently compensated by using the compensation capability of the dispersion-compensators and the red chirping on the transmitting side.Type: GrantFiled: August 24, 2006Date of Patent: August 28, 2007Assignee: Fujitsu LimitedInventors: Akira Miyauchi, Kazuo Yamane, Yumiko Kawasaki, Satoru Okano
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Patent number: 7262913Abstract: In a chromatic dispersion and dispersion slope compensating apparatus according to the present invention, a WDM light which has been angularly dispersed to a first direction by a VIPA plate, is angularly dispersed to a second direction vertical to the first direction by a diffraction grating, and optical signals of respective wavelengths output from the diffraction grating are reflected by any one of a plurality of three-dimensional mirrors having reflective surfaces of curved shapes different from each other, to be returned to the VIPA plate. Thus, with a simple control mechanism in which the plurality of three-dimensional mirrors are moved to only the second direction, an apparatus capable of variably compensating for the chromatic dispersion and the dispersion slope independent of each other can be provided.Type: GrantFiled: June 29, 2005Date of Patent: August 28, 2007Assignee: Fujitsu LimitedInventors: Akira Miura, Hiroki Ooi, Yasuhiro Yamauchi, Yoshinobu Kubota
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Publication number: 20070189775Abstract: A network element (5) for use in a wavelength division multiplex (WDM) optical transmission system (1). The WDM optical transmission system (1) comprises at least one demultiplexing means (5c) adapted to demultiplex a received WDM signal into constituent wavelength channels carrying tributary signals with at least a first and at least a second data rate (DR1, DR2). The optical transmission system (1) further comprises at least one first dispersion compensating module (5e) connected with the demultiplexing means for receiving constituent wavelength channels carrying tributary signals having said first data rate (DR1). Furthermore, the optical transmission system comprises at least one bypass bypassing the first dispersion compensating module and connected with the demultiplexing means for receiving constituent wavelength channels carrying tributary signals having said second data rate (DR2).Type: ApplicationFiled: December 12, 2006Publication date: August 16, 2007Applicant: ALCATEL LUCENtInventors: Gabriel Charlet, Jean-Christophe Antona
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Patent number: 7257292Abstract: The dispersion compensator with an etalon and a mirror arranged in parallel or at a slight angle with respect to each other is constructed so that emitted light from a collimator is reflected by the etalon multiple times and then enters another collimator. The dispersion compensator also has dispersion compensating units that change temperature using a heater or equivalent in order to render the amount of dispersion variable. In addition, these dispersion compensating units are provided in multi-stage form, and the angle of the mirror, the amplitude reflectance of the etalon, and temperature are optimized to offer polygonal dispersion characteristics. This realizes a practical, variable dispersion compensator suitable for a wavelength division multiplex optical transmission system and capable of shifting a variable amount of dispersion to the plus or minus side.Type: GrantFiled: July 11, 2006Date of Patent: August 14, 2007Assignee: Hitachi Metals, Ltd.Inventors: Toshiki Sugawara, Satoshi Makio
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Patent number: 7254333Abstract: A WDM (Wavelength Division Multiplex) terminal device located in a WDM network includes a multiplexing unit that multiplexes a wavelength of a client signal having a single wavelength or a wavelength of at least one of a first plurality of client signals whose wavelengths are multiplexed, to wavelengths of a second plurality of client signals received with their wavelengths being multiplexed, and transmits the second plurality of client signals. Thus, the WDM terminal device can multiplex wavelengths of a plurality of client signals received from a metro WDM terminal device located at a distant place, to a wavelength of another client signal without separating the plurality of client signals by each wavelength, thereby achieving accommodation of a plurality of client signals whose wavelengths are multiplexed, at low cost.Type: GrantFiled: September 24, 2001Date of Patent: August 7, 2007Assignee: Fujitsu LimitedInventor: Takayuki Shimizu
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Publication number: 20070177876Abstract: A chromatic dispersion monitoring apparatus according to the present invention comprises: a photodetector which photo-electrically converts an optical signal; a low-pass filter which limits a frequency bandwidth of the photo-electrically converted electrical signal to be within a range set according to a modulation format of the optical signal and a bit rate thereof; a DC elimination circuit which eliminates a direct current component of the bandwidth limited electrical signal; and a power detector which detects the power of the bandwidth limited electrical signal to detect the residual dispersion of the optical signal. As a result, it becomes possible to easily realize the chromatic dispersion monitoring apparatus of low cost, which is also capable to be arranged on an in-line.Type: ApplicationFiled: June 27, 2006Publication date: August 2, 2007Applicant: FUJITSU LIMITEDInventors: Hiroki Ooi, Akira Miura, Hiroshi Onaka
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Publication number: 20070177877Abstract: A low-cost configuration of, and at the same time to control the variable dispersion compensator at a high speed in a variable dispersion compensator for compensating the wavelength dependent accumulated dispersion resulting from the wavelength dependency of the transmission fiber and fixed dispersion compensator in a long-distance high-speed WDM transmission system. In order to achieve the object mentioned above, the wavelength dependent representative characteristic of the transmission fibers 4-1 . . . n, and the wavelength dependent representative characteristic of the DCFs 13-1 . . . n are recorded and maintained in advance in the dispersion control circuit 5-1 . . .Type: ApplicationFiled: January 24, 2007Publication date: August 2, 2007Inventor: Kenro Sekine
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Publication number: 20070172242Abstract: A regenerator (7.x, 7.1-7.3) for regenerating optical signals on optical transmission links (4), in particular for use in a Dense Wavelength Division Multiplex (DWDM) optical transmission system. The regenerator (7.x, 7.1-7.3) comprises optical amplification means (7.xa, 7.xd) for compensating optical power losses, and a deterministic adaptation unit (7.xb) comprising means being adapted to compensate deterministic transmission impairments of the optical transmission link (4), in particular optical dispersion compensating means being adapted to compensate for chromatic dispersion of said link (4). The proposed regenerator (7.x, 7.1-7.3) further comprises a non-deterministic adaptation unit (7.xc) comprising means for compensating time variant non-deterministic transmission impairments, in particular polarisation mode dispersion.Type: ApplicationFiled: December 7, 2006Publication date: July 26, 2007Applicant: ALCATEL LUCENTInventor: Gustav VEITH
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Patent number: 7248799Abstract: A device (D) is dedicated to controlling the power of optical signals in a transparent switching node of an optical communication network that switches bands of wavelengths. The device includes, firstly, a controller (12) for comparing input optical power measurements to a selected first threshold and generating instructions representative of the comparison result, secondly, a measuring device (10A) for delivering measurements representative of the input optical power of the optical signals at one output at least of the switch (4), and thirdly, a processor between the switch (4) and the multiplexer (6) of the node and which control the optical power of the signals coming from the switch (4) as a function of the instructions they receive, so that the optical power of the signals at the input of the multiplexer (6) is maintained substantially constant.Type: GrantFiled: December 23, 2003Date of Patent: July 24, 2007Assignee: AlcatelInventors: Jean-Paul Faure, Franck Pain
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Publication number: 20070166043Abstract: A method is provided for increasing downstream bandwidth in an optical network that includes providing a downstream terminal comprising a digital output path and an analog output path. The method also includes receiving a signal comprising at least one wavelength at the downstream terminal. The method further includes selectively processing the signal at the downstream terminal. The signal is selectively processed at the downstream terminal by processing the signal on the analog output path if the signal comprises analog video data and processing the signal on the digital output path if the signal comprises data to be converted to a digital bit stream.Type: ApplicationFiled: January 5, 2007Publication date: July 19, 2007Applicant: Fujitsu LimitedInventors: Martin Bouda, Takao Naito
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Patent number: 7242868Abstract: Processing a received optical signal in an optical communication network includes equalizing a received optical signal to provide an equalized signal, demodulating the equalized signal according to an m-ary modulation format to provide a demodulated signal, decoding the demodulated signal according to an inner code to provide an inner-decoded signal, and decoding the inner-decoded signal according to an outer code. Other aspects include other features such as equalizing an optical channel including storing channel characteristics for the optical channel associated with a client, loading the stored channel characteristics during a waiting period between bursts on the channel, and equalizing a received burst from the client using the loaded channel characteristics.Type: GrantFiled: June 10, 2004Date of Patent: July 10, 2007Inventors: Alexander I. Soto, Walter G. Soto
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Patent number: 7227686Abstract: Tunable PMD emulators and compensators for producing different PMD profiles with an adjustable average DGD value.Type: GrantFiled: March 8, 2005Date of Patent: June 5, 2007Assignee: General Photonics CorporationInventors: Lianshan Yan, X. Steve Yao
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Patent number: 7221871Abstract: A monitoring system is described that is comprised of a processing system and a database system. The database system is configured to store identities for a plurality of channels in the communication network. The processing system identifies an error on a first channel of the plurality of channels. The processing system identifies a second channel of the plurality of channels that is adjacent to the first channel based on the database system and determines if an error occurs on the second channel. The processing system identifies a third channel of the plurality of channels based on database system and determines if an error occurs on the third channel. The processing system identifies polarization-mode dispersion based on determining the error occurs on the second channel and determining the error does not occur on the third channel.Type: GrantFiled: July 17, 2003Date of Patent: May 22, 2007Assignee: Sprint Communications Company L.P.Inventors: Douglas Lew Richards, Christopher Thomas Allen, Douglas Charles Hague, Mark Loyd Jones
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Patent number: 7218818Abstract: A dispersion compensating fiber whose chromatic dispersion is positive and a negative dispersion compensating fiber whose chromatic dispersion is negative are prepared, and division-multiplexed optical signals, after being guided to either dispersion compensating fiber to once shift the whole wavelength band to positivity or negativity, are subjected to fine adjustment with a dispersion compensating fiber of a reverse sign.Type: GrantFiled: July 28, 2005Date of Patent: May 15, 2007Assignee: Hitachi Communication Technologies, Ltd.Inventors: Yasuyuki Fukashiro, Hiroyuki Nakano, Tetsuya Uda, Tooru Hirai
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Patent number: 7218856Abstract: A transmitted optical signal is first subjected to polarization mode dispersion compensation by a polarization mode dispersion compensator (PMDC), and then, its chromatic dispersion is compensated by a variable chromatic dispersion compensator (VDC) after the polarization mode dispersion compensation. How much the optical transmission signal suffers from polarization mode dispersion, which is needed to perform the polarization mode dispersion is measured using a Stokes parameter that is not affected by chromatic dispersion.Type: GrantFiled: September 27, 2004Date of Patent: May 15, 2007Assignee: Fujitsu LimitedInventors: Tomoo Takahara, Jens C. Rasmussen, Hiroki Ooi, George Ishikawa
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Patent number: 7209665Abstract: An apparatus is provided for compensating for polarization mode dispersion which is caused during transmission of a light wave via an optical waveguide, to an optical communication network having such an apparatus, and a method for compensating for polarization mode dispersion which is caused during transmission of a light wave via an optical waveguide is also provided.Type: GrantFiled: September 10, 2002Date of Patent: April 24, 2007Assignee: Siemens AktiengesellschaftInventors: Christoph Glingener, Klaus Kotten, Erich Gottwald
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Patent number: 7206516Abstract: The invention pertains to optical fiber transmission systems, and is particularly relevant to transmission of large volumes of data over long distances at high rates. An improved apparatus and method for measuring dispersion in a fiber span is disclosed. In particular, the invention teaches a highly accurate technique for measuring the fiber dispersion at a single wavelength. Transmitter and receiver structure and data processing algorithms are disclosed. An improved apparatus and method for measuring dispersion in a fiber span. In particular, the invention teaches a highly accurate technique for measuring the fiber dispersion at a single wavelength. Transmitter and receiver structure and data processing algorithms are disclosed.Type: GrantFiled: April 30, 2003Date of Patent: April 17, 2007Assignee: Pivotal Decisions LLCInventor: Michael H. Eiselt
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Patent number: 7203400Abstract: A dispersion compensator having relatively uniform transmission characteristics over the bandwidth of a communication channel. The compensator is designed to process an optical signal corresponding to the communication channel by decomposing that signal into spectral components, routing different components along different optical paths that impart relative delays between the components, and recombining the delayed components spatially and directionally to generate a processed optical signal with reduced chromatic dispersion. In one embodiment, the compensator is a waveguide circuit that includes four diffraction gratings operating in transmission and optically coupled to a tunable lens array, in which different tunable lenses receive light corresponding to different communication channels. For each channel, a desired group delay value is produced by selecting magnification strength of the corresponding tunable lens.Type: GrantFiled: November 16, 2005Date of Patent: April 10, 2007Assignee: Lucent Technologies Inc.Inventor: David T. Neilson
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Patent number: 7194208Abstract: A wavelength-division multiplexing optical transmission system for providing a compensating-purpose dispersion D2 to a wavelength-division multiplexing optical signal to be transmitted through an optical transmission path from a transmitter terminal to a receiver terminal. The compensating-purpose dispersion D2 satisfies conditions that at any wavelength “?” included in the transmission wavelength band, if dD1(?)/d??0 is established, then {dD1(?)/d?}×{dD2(?)/d?}<0 is also established, and if dD1(?)/d?=0 is established, then dD2(?)/d?=0 is also established, where D1 represents a dispersion generated in the wavelength-division multiplexing optical signal during when the wavelength-division multiplexing optical signal is transmitted through the transmission path from the transmitter terminal to the receiver terminal.Type: GrantFiled: February 3, 2003Date of Patent: March 20, 2007Assignee: NEC CorporationInventor: Hiroto Sugahara
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Patent number: 7184665Abstract: A chromatic dispersion compensator in a single-pass and a double-pass version is disclosed. In a single-pass version, the compensator has a diffractive grating for spatially separating an input optical signal into spatially spaced frequency components and a MEMS array of separate phase shifters, each for imparting an independent phase shift to a channel containing a range of the spatially spaced frequency components. In a double-pass version, a retroreflector is disposed to effect a double pass of the light beam through the grating and the phase shifters. The arrangement is effecting in reducing chromatic dispersion of the optical signal.Type: GrantFiled: June 7, 2002Date of Patent: February 27, 2007Assignees: JDS Uniphase Inc., JDS Uniphase CorporationInventors: Valentine N. Morozov, Sheldon McLaughlin, Thomas Ducellier
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Patent number: 7177541Abstract: It is disclosed that a method and apparatus that automatically monitors each channel's optical signal-to-noise ration (OSNR) using optical filter and polarization extinction method in wavelength division multiplexing (WDM) scheme-based optical transmission systems. OSNR is simply measured using optical filter by comparing amplified spontaneous emission (ASE) over the signal band, of which bandwidth has changed, while leaving signal intensity intact, with that original signal and, OSNR measurement is allowable over a wider range of OSNR by minimizing the ratio of signal to ASE over the signal band using polarization extinction method.Type: GrantFiled: November 9, 2001Date of Patent: February 13, 2007Assignee: TeraLink Communications, Inc.Inventors: Yun-Chur Chung, Jun-Haeng Lee
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Patent number: 7176428Abstract: The invention provides a multiphoton-excitation-type examination apparatus that efficiently generates a multiphoton-excitation effect, that makes the measurement head compact, and that can be easily adjusted when the measurement head is replaced. The multiphoton-excitation-type examination apparatus comprises a laser light source that oscillates ultrashort pulsed laser light; an optical fiber that transmits the ultrashort pulsed laser light from the laser light source; a support member; a measurement head supported on the support member so as to be movable upwards and downwards and at an angle, and having an optical system that irradiates a specimen with the ultrashort pulsed laser light transmitted by the optical fiber that measures fluorescence or reflected light coming from the specimen; and a dispersion-compensating member, in the measurement head, that compensates for group velocity dispersion of the ultrashort pulsed laser light irradiated onto the specimen.Type: GrantFiled: March 3, 2005Date of Patent: February 13, 2007Assignee: Olympus CorporationInventors: Yoshihiro Kawano, Tadashi Hirata, Tatsuo Nakata, Hiroshi Sasaki
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Patent number: 7174100Abstract: A method and system for performing OTDM. Laser wavelength tuning is used to create appropriate time differentials between bits in a combined optical output data stream.Type: GrantFiled: April 2, 2001Date of Patent: February 6, 2007Assignee: Finisar CorporationInventor: John M. Wachsman
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Patent number: 7174098Abstract: This invention provides a technique for realizing low-cost optical signal waveform monitoring with improved realtimeness to be applied to signal quality monitoring in an actual optical transmission system, and a technique for stably controlling an optical transmitter/receiver and various compensators by means of this waveform monitoring. Opening/closing of a optical gate is controlled by means of a clock signal synchronized with an optical signal input from a photocoupler and having a period equal to the bit interval of data or N (N: a positive integer) times longer than the bit interval to allow each pulse of the optical signal for one bit of data to pass through the optical gate for only part of the time width of the gate. A photoelectric conversion element to which the optical signal transmitted through the optical gate for only part of the time width obtains an average light intensity of the input optical signal. Information on this average light intensity is output to a monitoring output section.Type: GrantFiled: December 19, 2003Date of Patent: February 6, 2007Assignee: NEC CorporationInventor: Yoshitaka Yokoyama
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Patent number: 7171076Abstract: A dispersion-slope compensator including a feedback-type optical filter constituted by a looped optical line; an input-and-output optical line which inputs and outputs optical signals; and optical couplers which couples the looped optical line and the input-and-output optical line at two or more positions so that a Mach-Zehnder interferometer is formed by a portion of the looped optical line and a portion of the input-and-output optical line which are located between two of the optical couplers. A portion of the optical path realizing an MZI arm which constitutes the Mach-Zehnder interferometer is spatially separated from the other portions of the optical path so that the optical length of the MZI arm can be variably adjusted, and an amount of compensation for dispersion slope can be variably set.Type: GrantFiled: September 27, 2005Date of Patent: January 30, 2007Assignee: Fujitsu LimitedInventor: Kohei Shibata
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Patent number: 7171127Abstract: An optical transmission controller includes a semiconductor-laser, a semiconductor laser driver, a monitor photoreceptor, a waveform detector and a phase relation adjuster. The semiconductor laser driver allows the semiconductor laser to output an optical signal. The monitor photoreceptor monitors the optical signal output. The waveform detector detects a fall state of the optical signal output. The phase relation adjuster adjusts a phase relation between a fall timing of an input current and a variation timing of a relaxation oscillation of the optical signal output in accordance with a detection result of the waveform detector.Type: GrantFiled: November 18, 2003Date of Patent: January 30, 2007Assignee: Sharp Kabushiki KaishaInventor: Toshihisa Matsuo
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Patent number: 7164864Abstract: An optical communications system and transmission section repair method is provided to prevent the dispersion value in an optical receive station from being affected when a transmission line has been obstructed, wherein a patch is made into the transmission line adjusted for dispersion in the relay section of the transmission line. The transmission line includes positive dispersion fiber and negative dispersion fiber. The optical fiber used to patch the transmission line is an optical fiber where the absolute value of the dispersion is smaller than the dispersion value of the positive dispersion fiber or the negative dispersion fiber.Type: GrantFiled: February 15, 2001Date of Patent: January 16, 2007Assignee: Fujitsu LimitedInventors: Toshiki Tanaka, Takao Naito
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Patent number: 7151898Abstract: A polarization mode dispersion (PMD) feedforward compensator compensates first and second order PMD. An optical signal is provided to a PMD detector that senses first and second order PMD in the optical signal and produces control signals for the PMD compensator. The PMD compensator comprises, in series, a first polarization controller, an adjustable delay, a second polarization controller, a first fixed delay, a third polarization controller and a second fixed delay.Type: GrantFiled: January 8, 2003Date of Patent: December 19, 2006Assignee: Massachusetts Institute of TechnologyInventors: Poh-Boon Phua, Hermann A. Haud
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Patent number: 7149432Abstract: Optical equalization across N (an integer, N>1) channels of a multi-channel link of a communications network, is accomplished by averaging effects of optical performance variations within each of the M (an integer, M>1) parallel data signals. At a transmitting end node of the link, each one of the M data signals are distributed across the N channels of the link. Thus a substantially equal portion of each data signal is conveyed through the link in each one of the N channels. At a receiving end node of the link, respective bit-streams received over the N channels to are processed recover the M data signals. As a result, bit error rates of the bit-streams received through each channel are averaged across the M data signals, all of which therefore have a substantially equal aggregate bit error rate.Type: GrantFiled: November 28, 2000Date of Patent: December 12, 2006Assignee: Nortel Networks LimitedInventors: Roland A. Smith, Kim B. Roberts
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Patent number: 7149424Abstract: A system and method for improving the transmission quality of a WDM optical communications system begins by determining the bit-error rate for an optical channel before forward error correction is performed at a receiver. The pre-corrective bit-error rate is fed back through a feed back circuit that includes a parameter adjustment module which adjusts an optical signal parameter based on the bit-error rate. As examples, the signal parameter may be a channel power, dispersion, signal wavelength, the chirp or eye shape of an optical signal. The feedback circuit may also adjust various parameters within the WDM system, including amplifier gain, attenuation, and power for one or more channels in the system. By adjusting these parameters based on a pre-corrective bit-error rate, transmission quality is improved and costs are lowered through a reduction in hardware.Type: GrantFiled: August 22, 2002Date of Patent: December 12, 2006Assignee: Siemens Communications, Inc.Inventors: Valey F. Kamalov, Albrecht Neudecker
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Patent number: 7146107Abstract: A tunable dispersion compensator whose passband center wavelength changes when the amount of dispersion compensation is changed is suitably adjusted. The relationship between temperature for keeping the center wavelength constant and the amount of dispersion compensation is stored in advance. After controlling the amount of dispersion compensation to achieve best or optimum transmission quality, the amount of dispersion compensation is converted into temperature in accordance with the stored relationship and, based on that, the temperature is controlled to keep the center wavelength constant.Type: GrantFiled: December 18, 2003Date of Patent: December 5, 2006Assignee: Fujitsu LimitedInventors: Kentaro Nakamura, Hiroki Ooi, Tomoo Takahara
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Patent number: 7139478Abstract: Embodiments of the invention include system for monitoring the effectiveness of pulse shaping in a nonlinear optical fiber (40). The spectral content of the pulse, after passing through the nonlinear fiber (40), provides an indication of how effectively the pulse was regenerated. A portion of the pulse exiting the nonlinear fiber is tapped off and its pulse energy is measured in at least one selected spectral region. The selected spectral region is one in which the pulse tends to gain energy when effective regeneration is taking place. The information concerning the effectiveness of pulse shaping in a nonlinear optical fiber is fed back to dynamically change the residual dispersion at the regenerator input. The spectral measurement leads to a control signal (48) to indicate a level of performance of the system, or to improve the performance of the system by adjusting an operational parameter.Type: GrantFiled: March 13, 2002Date of Patent: November 21, 2006Assignee: Fitel USA Corp.Inventors: Benjamin J. Eggleton, Tsing Hua Her, Stefan Hunsche, Gregory Raybon, John A. Rogers, Paul S. Westbrook
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Patent number: 7139489Abstract: A method of compensating for chromatic dispersion in an optical signal transmitted on a long-haul terrestrial optical communication system including a plurality of spans, including: allowing chromatic dispersion to accumulate over at least one of the spans to a first predetermined level; and compensating for the first pre-determined level of dispersion using a dispersion compensating fiber causing accumulation of dispersion to a second predetermined level. There is also provided a hybrid Raman/EDFA amplifier including a Raman portion and an EDFA portion with a dispersion compensating fiber disposed therebetween. An optical communication system and a method of communicating an optical signal using such a Raman/EDFA amplifier are also provided.Type: GrantFiled: November 16, 2001Date of Patent: November 21, 2006Assignee: Tyco Telecommunications (US) Inc.Inventors: Morten Nissov, Alexei A. Pilipetskii, Ekaterina Golovchenko, Jonathan Nagel, Sergey Ten
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Patent number: 7133619Abstract: An operation unit of a PMD compensation module includes a PBS (polarization beam splitter), a compensating part and a combiner. The PBS separates an optical input into a first polarized signal and a second polarized signal. The compensating part includes a fixed prism and a movable prism. The first polarized signal outputted from the PBS travels through the fixed prism and the movable prism in series. The light path of the first polarized signal in the movable prism is elongated or shortened according to a position of the movable prism. A continuously variable delay can thus be applied between the first and second polarized signals. The combiner recombines the first polarized signal received from the compensating part and the second polarized signal received from the PBS into an optical output signal.Type: GrantFiled: July 10, 2002Date of Patent: November 7, 2006Assignee: Hon Hai Precision Ind. Co., Ltd.Inventor: Shu-Lin Tai
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Patent number: 7130542Abstract: An optical transmission system includes a number of corresponding modular multiplexing and demultiplexing units used in transmitting and receiving an optical signal respectively. Additionally, compensation components compensate for optical dispersion experienced by the optical signal. The modular multiplexing and demultiplexing units are assembled in a cascade fashion at the transmit side and the receive side of the optical transmission system, respectively. The dispersion compensation components share dispersion compensation fiber across the cascaded units.Type: GrantFiled: July 16, 2004Date of Patent: October 31, 2006Assignee: Corvis CorporationInventors: Dalma Novak, Bo Pedersen, Quan-Zhen Wang
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Patent number: 7127182Abstract: A transmitter for optical communication systems includes a source of optical radiation, a source of complex non-information signals, and a modulator unit in communication with the source of optical radiation. The modulator unit is also in communication with the source of complex non-information signals. The modulator has an input adapted to receive information-bearing signals.Type: GrantFiled: October 16, 2002Date of Patent: October 24, 2006Assignee: Broadband Royalty Corp.Inventors: Paul J. Matthews, Paul D. Biernacki, Sandeep T. Vohra
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Patent number: 7127178Abstract: An optical extending device for use in transmission of optical signals which comprise at least one sequence of periodic optical signals, said optical device comprising: a first fiber optic having a characteristic dimensional propagation coefficient equal to ?1 and adapted to be connected to a single mode second fiber optic having a length equal to L0 and a characteristic dimensional propagation coefficient equal to ?0, wherein Lp, the length of said first fiber optic is substantially equal to {[T2/??L0*?0]/?1}*{1?MOD(L0/{T2/??L0*?0]/g(b)}} and wherein: n is an integer 1, 2, 3 . . . and is selected in accordance L0, the length of the single mode second fiber optic; T is a time period of the periodic optical signals; and MOD is the remainder obtained from dividing 10 by {[T2/??L0*?0]/?1}.Type: GrantFiled: June 28, 2001Date of Patent: October 24, 2006Assignee: ECI Telecom Ltd.Inventor: Uri Mahlab
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Patent number: 7123838Abstract: An optical time-division multiplex signal processing apparatus includes an optical dispersion part providing optical dispersion to an optical time-division multiplex signal and an optical clock signal, an optical detector coupled optically to the optical dispersion part for detecting a beat signal formed between the optical time-division multiplex signal and the clock signal in a superposed state, and a filter connected to an output terminal of the optical detector for filtering out an electric signal of a desired frequency band from an output electric signal of said optical detector.Type: GrantFiled: September 27, 2001Date of Patent: October 17, 2006Assignee: Fujitsu LimitedInventor: Tomoyuki Akiyama
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Patent number: 7123846Abstract: This optical receiving device for discriminating and recovering a data signal, which results from converting an optical signal input through a dispersion equalizer into an electrical signal and amplifying it to a pre-determined amplitude, by using a clock and data recovery circuit for discriminating a data signal at the decision point controlled to achieve the optimum position controls the dispersion characteristics of a dispersion equalizer so that the error count in the recovered data signal by using a clock and data recovery circuit will be minimized by controlling the eye pattern of the data signal which has been amplified to a pre-determined amplitude.Type: GrantFiled: July 17, 2002Date of Patent: October 17, 2006Assignee: NEC CorporationInventors: Tetsuo Tateyama, Takashi Kuriyama, Yoshihiro Matsumoto
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Patent number: 7116918Abstract: In a system connecting a transmitter and a receiver using transmission paths and repeaters (in-line amplifiers), red chirping whose ? parameter is positive is performed for an optical signal on a transmitting side. Each of the repeaters includes a dispersion-compensator for compensating the amount of dispersion on a preceding transmission path. The amount of dispersion compensation of the dispersion-compensator included in the transmitter is made constant. The dispersion-compensator included in the receiver is arranged in order to compensate the amount of dispersion on a preceding transmission path. A spread of a pulse width on a transmission path can be efficiently compensated by using the compensation capability of the dispersion-compensators and the red chirping on the transmitting side.Type: GrantFiled: April 30, 2003Date of Patent: October 3, 2006Assignee: Fujitsu LimitedInventors: Akira Miyauchi, Kazuo Yamane, Yumiko Kawasaki, Satoru Okano
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Patent number: 7116913Abstract: In an optical transmission system comprising a transmitter, a receiver, and a transmission line that connects the transmitter and the receiver, a dispersion compensator is disposed in the receiver. The transmitter comprises an E/O (electro-optical signal converter) and a post-amplifier. An optical signal that has been RZ-coded is supplied to the E/O. The transmitter pre-chirps the optical signal. The pre-chirp is performed by red-chirp of which the value of the chirping parameter ? is positive. When the pre-chirp is performed, the non-linear effect of the optical signal on the transmission line can be canceled. In addition, with the RZ coded signal, the inter-symbol interference can be alleviated. Thus, the total dispersion amount of the dispersion compensator can be suppressed. In addition, the power of the optical output can be increased.Type: GrantFiled: October 6, 2004Date of Patent: October 3, 2006Assignee: Fujitsu LimitedInventors: Akira Miyauchi, Kazuo Yamane, Yumiko Kawasaki, Satoru Okano
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Patent number: 7110681Abstract: Binary information is subjected to RZ encoding and multi-level encoding, and the encoded signal is optically modulated.Type: GrantFiled: October 13, 2000Date of Patent: September 19, 2006Assignee: Mitsubishi Denki Kabushiki KaishaInventor: Takashi Mizuochi
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Patent number: 7106970Abstract: To generate light with the degree of polarization zeroed and the spread of an optical spectrum suppressed even with temporal overlapping between optical pulses each of which is polarized orthogonally to the succeeding pulse, a polarization scrambler includes an optical pulse generator that generates optical pulses with an intensity waveform repetition period T/2 and an electrical field repetition period T in which the same intensity waveform is repeated every repetition period T/2 and in which phase is inverted every repetition period T/2, and an orthogonal polarization delay unit which receives each of the optical pulses, separates the optical pulse into two optical pulses with orthogonal states of polarization, and relatively shifts the temporal position of one of the two optical pulses from that of the other optical pulse by (2n?1)T/4 (n is a natural number) to generate light in which each pulse is polarized orthogonally to a succeeding pulse.Type: GrantFiled: May 20, 2005Date of Patent: September 12, 2006Assignee: Nippon Telegraph and Telephone CorporationInventors: Masamichi Fujiwara, Mitsuhiro Teshima, Noboru Takachio, Katsumi Iwatsuki
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Patent number: 7103283Abstract: A transmission characteristic compensation system enables to reduce the generation of transmission deterioration by estimating an initially selected control direction, and also to compensate in advance with a setting value estimation so as to suppress the generation of transmission deterioration in advance. The transmission characteristic compensation control system includes a variable compensator having a control circuit; and an optimal setting value calculation portion for calculating an optimal setting value for the control circuit, wherein the optimal setting value calculation portion estimates future transmission deterioration on a predetermined time-by-time basis to set into the control circuit the optimal setting value for compensating the estimated transmission deterioration performed by the variable compensator.Type: GrantFiled: April 17, 2002Date of Patent: September 5, 2006Assignee: Fujitsu LimitedInventors: Satoshi Mikami, Kouichi Sawada, Hiroshi Nishimoto
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Patent number: 7099531Abstract: An optical chromatic dispersion compensator (60) betters optical communication system performance. The dispersion compensator (60) includes a collimating means (61) that receives a spatially diverging beam of light from an end of an optical fiber (30). The collimating means (61) converts the spatially diverging beam into a mainly collimated beam that is emitted therefrom. An optical phaser (62) receives the mainly collimated beam from the collimating means (61) through an entrance window (63), and angularly disperses the beam in a banded pattern that is emitted from the optical phaser (61). A light-returning means (66) receives the angularly dispersed light and reflects it back through the optical phaser (62) to exit the optical phaser near the entrance window (63) thereof.Type: GrantFiled: July 15, 2003Date of Patent: August 29, 2006Assignee: Chromatic Micro Optics, Inc.Inventors: Yong Qin Chen, Fei Zhu
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Patent number: RE39785Abstract: In an optical transmission system, a multiplexer frequency-division-multiplexes a plurality of signals, and outputs the resultant signal to an FM modulator. The FM modulator converts the frequency-division-multiplexed signal into an FM modulated signal through frequency modulation using the frequency-division-multiplexed signal as an original signal. A frequency-divider converts the FM modulated signal into a frequency-divided FM modulated signal whose frequency is ½n (n is an integer of not less than 1) the frequency of the FM modulated signal. An optical modulator has a predetermined input-voltage vs. output-optical-power characteristic, and is biased at the minimum point (voltage) about the output optical power. The optical modulator modulates an unmodulated light fed from a light source with the applied frequency-divided FM modulated signal to produce an optical signal whose optical carrier component is suppressed, and sends the optical signal to an optical transmission line.Type: GrantFiled: November 26, 2004Date of Patent: August 21, 2007Assignee: Matsushita Electric Industrial Co., Ltd.Inventor: Masaru Fuse