Dispersion Compensation Patents (Class 398/147)
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Patent number: 7965949Abstract: A robustly stabilized communication laser can output a multimode optical signal remaining aligned to a coordinate of a dense wavelength division multiplexing (“DWDM”) grid while responding to a fluctuating condition or random event, such as, without limitation, exposure to a temperature fluctuation, stray light, or contamination. Responsive to the fluctuating condition, energy can transfer among individual modes in a plurality of aligned longitudinal modes. Modes shifting towards a state of misalignment with the DWDM coordinate can attenuate, while modes shifting towards a state of alignment can gain energy. Fabrication processes and systems and light management, such as beam steering, epoxy scaffolds, spectral adjustments, mode matching, thermal expansion control, alignment technology, etc. can facilitate nano-scale control of device parameters and can support low-cost fabrication.Type: GrantFiled: June 12, 2009Date of Patent: June 21, 2011Assignee: Cirrex Systems LLCInventor: Michael L. Wach
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Patent number: 7965945Abstract: One method configures an all-optical network such that at least eighty percent of optical fiber spans of a portion of a first all-optical path of the network have substantially a first residual dispersion per span and at least eighty percent of optical fiber spans of a remainder of the first all-optical path have residual dispersions per span substantially differing from the first residual dispersion per span. The remainder of the first all-optical path includes an overlap between the first all-optical path and a second all-optical path of the network. The second all-optical path has a plurality of optical fiber spans and a substantially singly periodic dispersion map.Type: GrantFiled: September 15, 2006Date of Patent: June 21, 2011Assignee: Alcatel-Lucent USA Inc.Inventors: Paul Robert Claisse, Rene′-Jean Essiambre
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Patent number: 7949257Abstract: One embodiment sets forth a technique for measuring chromatic dispersion using reference signals within the operational range of amplifiers used to refresh data signals. One red/blue laser pair in the transmission node is used for measuring dispersion and chromatic dispersion compensation is added at each line node in the system. Since reference and data signals propagate through each amplifier, the reference signals used to measure chromatic dispersion receive the same dispersion compensation (and will have the same residual dispersion) as the data signals. Therefore, any residual dispersion in the data signals will manifest itself in downstream dispersion measurements and, thus, can be corrected. The tunable dispersion compensator in each line node may be set to compensate for the measured dispersion, thereby compensating for both the chromatic dispersion of the link connecting the current node to the prior node and any uncorrected residual dispersion from prior nodes.Type: GrantFiled: November 12, 2007Date of Patent: May 24, 2011Assignee: Oclaro (North America), Inc.Inventors: Christopher Lin, Mark Summa, Martin Williams, Douglas Butler, Peter Wigley
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Patent number: 7933522Abstract: Influence of polarization mode dispersion, occurring in an optical fiber is mitigated by means of polarization scrambling, differential group delay which a received optical signal has is optically suppressed; the optical signal in which differential group delay is thus suppressed is converted into an electric signal; and error correcting processing is carried out on the electric signal obtained, a jitter amplitude in the received optical signal is suppressed, influence of which to a jitter tolerance increases due to increase in speed of the polarization scrambling.Type: GrantFiled: August 21, 2007Date of Patent: April 26, 2011Assignee: Fujitsu LimitedInventors: Jens Rasmussen, Akihiko Isomura
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Publication number: 20110076023Abstract: An embodiment of the invention includes a tunable optical dispersion compensator (TODC) comprising a first beam displacer on an optical path, wherein the first beam displacer separates an optical signal into a first beam and a second beam, and one or more polarizing beam splitters on the optical path, wherein the one or more polarizing beam splitters keep the first beam and the second beam on the optical path. The TODC also comprises one or more etalons on the optical path, wherein the one or more etalons are tunable to introduce a group delay in the first beam and the second beam, and a reflecting mirror on the optical path, wherein the reflecting mirror returns the optical signal back along the optical path. The TODC further comprises a second beam displacer, wherein the second beam displacer combines the first beam and the second beam into an output optical signal.Type: ApplicationFiled: September 29, 2009Publication date: March 31, 2011Applicant: FINISAR CORPORATIONInventors: Fan Chen, Yongkang Hu, Zhenli Wen, Dongshen Han, Fahua Lan, Kevin Dapeng Zhang
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Publication number: 20110058820Abstract: An optical transmission system includes an optical transmission equipment and an optical receiving device. The optical transmission equipment transmits an optical signal from a first adjacent node to a second adjacent node, and includes an optical multiplexing and demultiplexing unit that demultiplexes the optical signal from the first adjacent node into an optical transmission signal to be transmitted to the second adjacent node and an optical demultiplexed signal, and a compensating unit that partially compensates chromatic dispersion in the optical demultiplexed signal. The optical receiving device receives the optical signal from the optical transmission equipment, and includes a converting unit that converts the optical demultiplexed signal the chromatic dispersion of which is partially compensated by the compensating unit into an electric digital signal, and a digital processing unit that compensates chromatic dispersion remaining in the electric digital signal.Type: ApplicationFiled: August 31, 2010Publication date: March 10, 2011Applicant: FUJITSU LIMITEDInventor: Hiroki Ooi
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Patent number: 7885541Abstract: According to one aspect of the invention, an optical network including multiple optical network devices, or nodes, is provided. At each node, an optical performance monitor analyzes dispersion while a dispersion compensation module reduces the amount of dispersion in the signals. Information about the dispersion and the amount of compensation performed by the dispersion compensation module is generated by the optical performance monitor and stored in a memory. If the bit error rate of a particular path between nodes becomes too high, a new path is used. A monitoring computer then accesses the information about the dispersion stored in at least one node of the old path. The information allows a user to determine where along the path the greatest amount of dispersion is occurring.Type: GrantFiled: February 22, 2005Date of Patent: February 8, 2011Assignee: Dynamic Method Enterprises LimitedInventor: Christopher M. Look
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Patent number: 7885545Abstract: A dispersion compensation method comprising the steps of: a) providing a compensation node for each predetermined number of in-line repeaters; b) carrying out dispersion compensation for the in-line repeaters with the different bit rates in common; c) carrying out wavelength demultiplexing on the optical signal for each of the different bit rates in the compensation node; and d) setting an optimum dispersion compensation amount for the optical signal of each bit rate.Type: GrantFiled: October 25, 2004Date of Patent: February 8, 2011Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Akira Miura, Kentaro Nakamura, George Ishikawa
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Patent number: 7881610Abstract: Described is a method of transmitting an optical signal in an optical transmission system. The method comprises: providing a length of an optical fiber having a zero chromatic dispersion wavelength, wherein the optical fiber belongs to an optical fiber group and wherein the optical fiber group comprises optical fibers having a zero chromatic dispersion wavelength comprised within a wavelength range; estimating a tolerated chromatic dispersion range; and transmitting the optical signal over the length of optical fiber at a first transmission wavelength.Type: GrantFiled: April 28, 2006Date of Patent: February 1, 2011Assignee: AlcatelInventors: Giovanni Bellotti, Alessandro Iachelini
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Patent number: 7873283Abstract: The invention aims to provide a monitoring method that can measure an optical SNR in an ultra high speed optical transmission system with high accuracy, and an optical transmission system using the same. To this end, in the optical transmission system to which the monitoring method of the present invention is applied, the degree of polarization of an optical signal transmitted from an optical transmission apparatus to an optical receiving apparatus via an optical transmission path is measured by a DOP measuring device, and an optical SNR of the optical signal is determined by an optical SNR calculation circuit based on a measured value of the degree of polarization.Type: GrantFiled: September 16, 2003Date of Patent: January 18, 2011Assignee: Fujitsu LimitedInventors: Yuichi Akiyama, Takafumi Terahara
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Patent number: 7873282Abstract: A polarization multiplex transmission system (10) comprises two optical signals (z1, z2) transmitted over the same optical fiber (15) at the same wavelength but with orthogonal polarizations. The system is characterized by receiving apparatus (10) which is operable to filter the two components with orthogonal polarization of the signal received in accordance with an appropriate transfer matrix which is dynamically controlled on the basis of the output signals in such a manner as to approximate the reverse transfer matrix of the fiber in the region of the spectrum occupied by the signal so as to compensate for Polarization Mode Dispersion (PMD) and polarization rotation introduced by the fiber and eliminating distortion and mutual interference effects for both the signals and thereby obtain a demultiplexed output corresponding to the two transmitted signals.Type: GrantFiled: March 9, 2005Date of Patent: January 18, 2011Assignee: Ericsson ABInventors: Marco Secondini, Enrico Forestieri, Giancarlo Prati, Giulio Colavolpe
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Patent number: 7869715Abstract: A variable dispersion compensating unit compensates an optical signal, and changes the compensation amount according to a control signal that has a given frequency. After demodulation of the compensated optical signal, error conditions of the signal are monitored and an error signal is output. A band pass filter filters the error signal for a component having a frequency equal to or less than the given frequency. Based on the component and on the control signal, a synchronous detecting circuit generates a compensation amount modification signal. The compensation amount modification signal is superposed on the control signal.Type: GrantFiled: April 20, 2007Date of Patent: January 11, 2011Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Hiroshi Onaka, Takeshi Hoshida
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Patent number: 7869716Abstract: Described is a method and system for reducing system penalty from polarization mode dispersion. The method includes receiving a plurality of signals at a receiving end of a transmission line, each signal being received on one of a plurality of channels of the transmission line and measuring a signal degradation of at least one of the channels of the transmission line. An amount of adjustment of a polarization controller is determined based on the signal degradation, the amount of adjustment being selected to reduce the polarization mode dispersion. The amount of adjustment is then transmitted to the polarization controller.Type: GrantFiled: August 31, 2005Date of Patent: January 11, 2011Assignee: AT&T Intellectual Property II, L.P.Inventors: Mikhail Boroditsky, Mikhail Brodsky, Nicholas J. Frigo, Peter Magill
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Patent number: 7865082Abstract: The optical transmitter and receiver of the invention includes: a variable dispersion compensator that performs wavelength dispersion compensation on an optical signal of a differential M-phase modulation format input from a transmission path; an optical amplifier that compensates an optical loss in the variable dispersion compensator; a delay interferometer that delays and interference processes the optical signal output from the optical amplifier; and a photoelectric conversion circuit that photoelectric converts the output light from the delay interferometer to generate a demodulated electric signal. The output level of the optical amplifier is decreased at the time of start up to deteriorate the OSNR of the optical signal input to the photoelectric conversion circuit, to thereby realize a state in which an error occurs more easily, and then optimization control of the variable dispersion compensator and the delay interferometer is started.Type: GrantFiled: December 31, 2007Date of Patent: January 4, 2011Assignee: Fujitsu LimitedInventors: Toshiki Honda, Takeshi Ono
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Publication number: 20100329693Abstract: A system may comprise a single wavelength laser; a modulator optically coupled to said laser; a length of multi-mode fiber optically coupled to said modulator; and a phase mask optically coupled to said fiber. The phase mask may be configured to filter out modes other than a selected mode.Type: ApplicationFiled: June 30, 2009Publication date: December 30, 2010Applicant: Verizon Patent and Licensing Inc.Inventor: David Zhi Chen
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Patent number: 7848656Abstract: A method of operating a WDM transmission system with at least one transmitter and at least one receiver connected by means of a dispersive transmission line.Type: GrantFiled: April 9, 2007Date of Patent: December 7, 2010Assignee: AlcatelInventors: Jean-Christophe Antona, Bruno Lavigne
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Publication number: 20100296818Abstract: A method for cost-effective optical transmission with fast Raman tilt or other transient event control uses a combination of Erbium-doped fiber amplifiers (EDFAs) and Raman fiber amplifiers (RFAs), where EDFAs are used as the primary optical amplifiers to compensate the span loss while the RFA (advantageously a forward-pumped RFA) is used only in some specific spans with a feed-forward control circuit serving as a fast Raman tilt transient compensator, the RFA also serving as an optical amplifier. A long haul optical transmission system using feed-forward controlled RFA's periodically spaced along its length, for example, when add-drop multiplexing is used, makes full use of the economics of EDFAs and the fast tilt transient control capability of a RFA enabled by an adjustable speed feed-forward or feed-back control technique.Type: ApplicationFiled: November 4, 2008Publication date: November 25, 2010Applicant: AT & T Corp.Inventors: Xiang Zhou, Martin Birk
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Patent number: 7840139Abstract: The invention pertains to optical fiber transmission systems, and is particularly relevant to optical transport systems employing optical amplifiers. In particular the invention teaches an apparatus and method that allows cost effective co-directional operation of an optical amplifier to support full duplex traffic on a single fiber, and the design of an optical fiber transmission system based on this optical amplifier technology.Type: GrantFiled: July 31, 2008Date of Patent: November 23, 2010Inventors: Michael H. Eiselt, Lara Garrett, Marvin R. Young
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Patent number: 7831114Abstract: In a method and system for providing dispersion compensation in an optical system, there is coupled into the optical system at least one pathway into which there is connected a tunable chirped fiber Bragg grating, each such grating providing a respective tunable amount of dispersion. At least one respective DGD element is connected into the respective pathway for each such grating. The set of all such respective DGD elements in a given pathway introduces a bias differential group delay DGD(bias) having an absolute value that, for at least one tuning value of the grating, is substantially equal to differential group delay introduced by the grating.Type: GrantFiled: January 11, 2009Date of Patent: November 9, 2010Assignee: OFS Fitel LLCInventors: Gregory M. Bubel, William R. Holland, David J. Kudelko, Yaowen Li, Paul S. Westbrook
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Publication number: 20100266289Abstract: A method and system for processing analog optical signals to produce a single RF output free from even-order harmonic distortion. Two analog optical signals of different wavelengths ?1, ?2 are input into a dual-output Mach-Zehnder modulator (MZM), where one wavelength input is high-biased and one wavelength is low-biased. The complementary high- and low-biased wavelengths are output from each arm of the MZM to a multiplexer, which filters out the unwanted high- or low-biased wavelengths from each MZM arm so that both wavelengths are low-biased or high-biased. The signals are passed to a pair of photodiodes, and the photocurrents from the photodiodes are differenced to produce the final RF output. Because of the complementary phase differences between the two low- or high-biased signals generating the photocurrent, all components of the photocurrent except the fundamental and odd-order harmonics cancel each other, resulting in a high-quality RF output free from harmonic distortion.Type: ApplicationFiled: January 15, 2010Publication date: October 21, 2010Applicant: The Government of the US, as represented by the Secretary of the NavyInventors: Preetpaul S. Devgan, Vincent J. Urick, Keith J. Williams, John F. Diehl, Christopher E. Sunderman
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Patent number: 7813647Abstract: A chromatic dispersion compensation control method for compensating the chromatic dispersion of an optical transmission path with a variable dispersion compensator inserted in the optical transmission path is disclosed.Type: GrantFiled: December 5, 2007Date of Patent: October 12, 2010Assignee: Fujitsu LimitedInventor: Toshihiro Ohtani
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Patent number: 7805082Abstract: An optical communications system comprises a transmitter, a receiver and an optical communications link between the transmitter and receiver. The transmitter comprises a current-driven directly modulated laser for providing a modulated optical signal and a current controller for controlling the current waveform applied to the laser. The current waveform applied to the laser is determined to compensate for the effects of the laser non-linearities and the fiber chromatic dispersion. This system applies pre-compensation to the directly modulated laser input current waveform to provide both pre-compensation for chromatic dispersion and compensation for the non-linearities of the directly modulated laser. These are two of the main limiting factors in providing a low cost high data rate and long reach optical communications system.Type: GrantFiled: September 21, 2004Date of Patent: September 28, 2010Assignee: Ciena CorporationInventor: James Edward Whiteaway
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Publication number: 20100221013Abstract: An optical transmission apparatus for suppressing deterioration of transmission quality due to XPM in a wavelength division multiplexing optical communication system in which an intensity modulation optical signal and a phase modulation optical signal exist in a mixed form. The apparatus has an intensity inversion signal light output section which outputs light having an intensity pattern obtained by inverting intensity changes of the intensity modulation optical signal near a wavelength of the intensity modulation optical signal in arrangement on wavelength axis of optical wavelengths that can be multiplexed as a wavelength division multiplexed signal as intensity inversion signal light, and a wavelength division multiplexed optical signal output unit which wavelength-division-multiplexes the intensity modulation optical signal, the phase modulation optical signal and light from the intensity inversion signal light output section and outputs a wavelength division multiplexed optical signal.Type: ApplicationFiled: January 15, 2010Publication date: September 2, 2010Inventors: Hiroki OOI, Hiroshi Onaka, George Ishikawa
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Patent number: 7787775Abstract: A chromatic dispersion compensation system for an optical transmission system incorporates circuitry which determines the length of an optical fiber extending between an output amplifier and an input amplifier. Based on fiber type, the total chromatic dispersion on the fiber is determined. Compensation can then be automatically implemented.Type: GrantFiled: September 13, 2006Date of Patent: August 31, 2010Assignee: Tellabs Operations, Inc.Inventors: Mark E. Boduch, Kimon Papakos, Gary M. Eslary, John M. Golding
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Publication number: 20100215377Abstract: In an optical network design apparatus, a constraint setter sets a first constraint that one of alternative values given beforehand is selected as the dispersion compensation amount of each node, sets a first margin value that assumes a nonnegative value, sets a second constraint that the first margin value is equal to or greater than the difference between the residual dispersion and the lower bound of an allowable range, sets a second margin value that assumes a nonnegative value, and sets a third constraint that the second margin value is equal to or greater than the difference between the upper bound of the allowable range and the residual dispersion. A calculation controller generates an objective function including the first, second and third constraints and including a summation of the first and second margin values for all paths, and derives a solution that minimizes the objective function.Type: ApplicationFiled: November 18, 2009Publication date: August 26, 2010Applicant: FUJITSU LIMITEDInventors: Kazuyuki TAJIMA, Toru Katagiri, Tomohiro Hashiguchi, Yutaka Takita
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Patent number: 7783201Abstract: An optical repeater device of the present invention comprises: a preamble compensating circuit 53, for taking out a normal data signal from burst signals propagating through a communication transmission path, and for adding a preamble signal before and/or after the data signal. Furthermore, the preamble compensating circuit 53 comprises: a detector circuit 53a, for inputting the burst signal, and for outputting only the normal data signal; a buffer circuit 53b, for storing the data signal output from the detector circuit 53a, and for outputting thereof; a preamble signal generation circuit 53d, for outputting at least one type of the preamble signal; and an data output select circuit 53e, for outputting the data signal at the time of the data signal input from the buffer circuit 53b, and for outputting the preamble signal from the preamble signal generation circuit 53d at any other time thereof.Type: GrantFiled: March 11, 2008Date of Patent: August 24, 2010Assignee: The Furukawa Electric Co., Ltd.Inventors: Masayuki Miura, Kunio Odaka, Fuyuki Takeuchi
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Publication number: 20100209115Abstract: Systems and methods for frequency-domain compensation in optical communication systems. In pre-equalization embodiments, the transmitter transforms the data stream into a frequency domain signal and applies a compensation filter before transforming it back into a pre-distorted time domain signal. As the pre-distorted time domain signal propagates through the optical channel, optical dispersion effects counter the pre-distortion, producing an equalized signal at the channel output. In post-equalization embodiments, the receiver transforms the received signal into a frequency domain signal and applies a compensation filter before transforming it back into an equalized time domain signal. Pre-equalization may prove less expensive due to the square-law characteristic of photodetectors employed by most receivers.Type: ApplicationFiled: April 23, 2010Publication date: August 19, 2010Applicant: MENARA NETWORKS, INC.Inventors: Salam ELAHMADI, Siraj Nour ELAHMADI
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Patent number: 7773283Abstract: According to an aspect of an embodiment, an optical modulation device includes a Mach-Zehnder modulator and a controller. The Mach-Zehnder modulator is supplied a drive signal and a bias voltage. The Mach-Zehnder modulator modulates inputted light on the bases of the drive signal and the bias voltage. The drive signal selectively is superimposes a predetermined frequency signal. The bias voltage selectively is superimposes the predetermined frequency signal. The controller selects a superimposing target which is the drive signal or the bias voltage so as to change modulation formats.Type: GrantFiled: March 28, 2008Date of Patent: August 10, 2010Assignee: Fujitsu LimitedInventors: Toshiki Tanaka, Hideyuki Miyata, Yuichi Akiyama, Takeshi Hoshida
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Patent number: 7769298Abstract: The present invention provides a pulse train generator comprising: a dual-frequency signal light source for generating a dual-frequency signal; a soliton shaper for soliton-shaping output light from the dual-frequency signal light source; and an adiabatic soliton compressor for performing adiabatic soliton compression on output light from the soliton shaper, and also provides a waveform shaper used in this pulse train generator, including a plurality of highly nonlinear optical transmission lines and a plurality of low-nonlinearity optical transmission lines which has a nonlinearity coefficient lower than that of the plurality of highly nonlinear optical transmission lines and which has a second-order dispersion value of which an absolute value is different from that of the plurality of highly nonlinear optical transmission lines.Type: GrantFiled: September 25, 2008Date of Patent: August 3, 2010Assignee: The Furukawa Electric Co., Ltd.Inventors: Koji Igarashi, Yoshihiro Emori, Atsushi Oguri, Shu Namiki, Osamu Aso, Masateru Tadakuma
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Patent number: 7769299Abstract: 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: GrantFiled: June 27, 2006Date of Patent: August 3, 2010Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Akira Miura, Hiroshi Onaka
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Patent number: 7769300Abstract: A method and device for reducing the distortion of optical pulses caused by the polarization mode dispersion in optical communication systems is provided. When an optical pulse having any polarization is transmitted through an optical communication system, which is optically anisotropic, at least in sections, the optical pulse may become distorted due to the different velocities of the various polarization components. This distortion of the optical pulses may reduces the maximum transmission rate of the system. A method is provided for functioning in response to the detected transmission quality of the communication system where a polarization-controlling device for setting the polarization of the optical pulse is driven in such a way that the transmission quality is maximized. An optical communication system, including an optical transmission medium, involves a device for determining the transmission quality of the communication system, a regulating device, and a polarization-controlling device.Type: GrantFiled: January 17, 2000Date of Patent: August 3, 2010Assignee: Deutsche Telekom AGInventors: Wolfgang Dultz, Leonid Beresnev, Erna Frins, Franko Kueppers, Heidrun Schmitzer, Joachim Vobian, Werner Weiershausen
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Patent number: 7751713Abstract: Embodiments of the present invention route a WDM signal across multiple communication paths using skew characteristics of at least some of the communication paths. The network is an optical transport network, using either circuit or packet based switching, and wavelength division multiplexed wavelengths and/or optical carrier groups (“OCGs”) over a fiber link to another node in the network. The plurality of communication paths involves different signal and path attributes such as a plurality of carrier wavelengths, optical carrier groups, physical communication paths (different nodes, different fibers along a same path, or any combination of the foregoing), or any other differentiating factors between two paths.Type: GrantFiled: July 23, 2007Date of Patent: July 6, 2010Assignee: Infinera CorporationInventors: Drew D. Perkins, David F. Welch, Ting-Kuang Chiang, Charles H. Joyner, Edward E. Sprague, Parthiban Kandappan, Stephen G. Grubb, Biao Lu, Prasad Paranjape
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Patent number: 7751706Abstract: In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.Type: GrantFiled: November 10, 2008Date of Patent: July 6, 2010Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Takashi Iwabuchi, Takafumi Terahara, Junichi Kumasako, George Ishikawa, Tomoo Takahara
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Patent number: 7747171Abstract: A method and apparatus is provided for reducing impairment to an adiabatically chirped optical signal propagating in an optical communication system. The method begins by receiving an adiabatically chirped optical signal that has traversed one or more network components in the optical communication system. The optical signal has a parameter characteristic of signal quality (e.g., an extinction ratio) that is reduced at least in part by a fidelity-degrading transmission slope accumulated in the one or more network components. A fidelity-enhancing transmission slope imparted to at least one wavelength of the adiabatically chirped optical signal at one or more select points along a transmission path of the communication system so that the optical signal experiences an increase in said parameter characteristic of signal quality.Type: GrantFiled: September 10, 2002Date of Patent: June 29, 2010Assignee: Meriton Networks US Inc.Inventors: Per Bang Hansen, Torben N. Nielsen, Lars Erik Eskildsen
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Patent number: 7747175Abstract: To compensate a waveform distortion by using a nature that a spectral shape is perfectly retained even if all the linear distortions occur on a time-axis. An optical pulse transmitted from an optical pulse transmitter (1) via an optical fiber transmission line (2) is transmitted. An optical Fourier transformer (3) receives an optical pulse, and optically Fourier-transforms an optical pulse on a time-axis onto a frequency-axis to reproduce the frequency spectrum of an optical pulse on a time-axis be effecting switching between frequency and time, thereby compensating a waveform distortion by a linear effect on the optical fiber transmission line (2). A photodetector (4) receives an optical pulse from the optical Fourier transformer (3) and transforms this into an electrical signal to thereby obtain a pulse waveform before a transmission over the optical fiber transmission line (2).Type: GrantFiled: January 23, 2004Date of Patent: June 29, 2010Assignee: Japan Science and Technology AgencyInventors: Toshihiko Hirooka, Masataka Nakazawa
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Patent number: 7742703Abstract: An apparatus and method are applied to characterizing an dispersion-affecting element for use in controlling chromatic dispersion in an optical communications link. Information regarding the behavior of the dispersion-affecting element is recorded and stored in a medium that is provided for deployment with the dispersion-affecting element to enable improved management and active control of the dispersion-affecting element. The suitability of the dispersion-affecting element for operating under different conditions may also be characterized.Type: GrantFiled: June 12, 2009Date of Patent: June 22, 2010Assignee: Verizon Business Global LLCInventors: John A Fee, Frank A McKiel
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Patent number: 7742706Abstract: A dispersion compensation type optical signal receiving apparatus includes: an APD element for converting input signal light inputted from a transmission line into an electric signal; an amplifying device constituted with a preamplifier circuit and a limit amplifier circuit, which amplifies the electric signal converted by the APD element; an EDC IC for compensating the dispersion in the transmission line electrically; and a clock/data reproducing circuit for reproducing the clock and data signal contained in the input signal light, wherein there is provided a VOA for limiting the amplitude of the input signal light inputted to the APD element and an attenuation amount controlling circuit for controlling the attenuation amount of the VOA in accordance with the bias current of the APD element.Type: GrantFiled: March 23, 2007Date of Patent: June 22, 2010Assignee: NEC CorporationInventor: Tatsuya Uchikata
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Patent number: 7734186Abstract: A method of reducing Raman tilt in a transmission apparatus capable of transmitting a plurality of signals, occupying contiguous channels in a transmission band, through a length of optical transmission cable which exhibits the Raman effect of transferring energy from the shorter wavelength signals at one end of the transmission band towards the longer wavelength signals at the other end of the transmission band, including the transmission of half the maximum number of signals at twice the normal channel frequency spacing at a higher-than-normal level and the transmission signals in selected ones, fewer than all, of the available channels at the normal channel spacing at a normal power level. As new channels are added at the lower frequency channel spacing, the powers of both neighboring channels are reduced to the normal power level.Type: GrantFiled: September 17, 2002Date of Patent: June 8, 2010Assignee: Ericsson ABInventors: Marc Francis Charles Stephens, Steven Alleston, Nicholas John Doran
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Patent number: 7734187Abstract: Dispersion may be managed in an optical network configured to transmit differential phase shift keying (DPSK) modulated signals by allowing accumulation of dispersion to thousands of ps/nm before compensating. A dispersion map providing a negative average dispersion and a minimum dispersion wavelength outside of the signal band may be employed.Type: GrantFiled: August 11, 2005Date of Patent: June 8, 2010Assignee: Tyco Electronics Subsea Communications LLCInventors: Alexei N. Pilipetskii, Ekaterina A. Golovchenko, William T. Anderson, Alan J. Lucero
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Patent number: 7729619Abstract: In order to enhance dispersion control, the apparatus includes a dispersion controller; a quality index generator generating a quality index representing a quality of an optical signal output from the dispersion controller; and a searching unit searching for an amount of dispersion control applying to the dispersion controller which amount optimizes the quality index, wherein the searching unit includes a splitting-half searching unit roughly searching, in a splitting half method, a range in which dispersion is controllable by the dispersion controller for an amount of dispersion control such that the quality index generated by the quality index generator becomes preferable, and a sweep searching unit thoroughly searching, by sweeping, a limited range based on the amount of dispersion searched by the splitting-half searching unit for an amount of dispersion control that optimizes the quality index generated by the quality index generator.Type: GrantFiled: December 5, 2008Date of Patent: June 1, 2010Assignee: Fujitsu LimitedInventors: Kiyotoshi Noheji, Hiroki Ooi
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Patent number: 7725042Abstract: An automated optical transport system is provided which provides for automatic discovery of system components, automatic inventory of system components, automatic topology detection, automatic provisioning of channels, and automatic characterization and tuning of system components and fiber. The invention provides automation capability through inclusion of management card capabilities at each station which communicates through a reverse propagating service channel. Dynamic and propagation direction independent segments are provided in conjunction with a token-based scheme to repeatedly tune, update and monitor the transport system.Type: GrantFiled: April 22, 2003Date of Patent: May 25, 2010Inventors: Marvin Ray Young, Michael H. Eiselt, Daniel Nooner, Jeffrey Pearlman, Michael L. Cooper
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Patent number: 7725032Abstract: An optical transmission apparatus includes an optical add drop multiplexer (OADM) that adds/drops an optical signal to/from a transmission path. The optical transmission apparatus further includes a pump light multiplexer and a dispersion compensation fiber that are located downstream of the OADM on the transmission path. The optical transmission apparatus is configured to house a pump light source connectable to the pump light multiplexer to Raman amplify an optical signal in the dispersion compensation fiber.Type: GrantFiled: December 29, 2005Date of Patent: May 25, 2010Assignee: Fujitsu LimitedInventors: Miki Onaka, Yasushi Sugaya, Hiroki Ooi
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Publication number: 20100119237Abstract: A dynamic tunable chromatic dispersion compensator with low latency is provided that includes a chirped fiber Bragg grating in a compensating optical fiber core. The chirped fiber Bragg grating includes wavelength gratings spaced at distances varying with respect to the length of the compensating optical fiber core to compensate for differential delay in a synchronous time protocol for a bidirectional computer data communication link. The dynamic tunable chromatic dispersion compensator also includes one or more controllable elements to modify the length of the compensating optical fiber core in response to one or more commands, and an optical junction to optically couple the chirped fiber Bragg grating to an optical fiber of the bidirectional computer data communication link.Type: ApplicationFiled: November 7, 2008Publication date: May 13, 2010Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventor: Casimer M. DeCusatis
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Publication number: 20100119225Abstract: A transceiver card for a telecommunications box for transmitting data over a first optical fiber and receiving data over a second optical fiber. The card has transmitter for transmitting data over the first optical fiber, the transmitter having a laser and a modulator, a fiber output optically connected to the laser for connecting the first optical fiber to the card, a fiber input for connecting the second optical fiber to the card, a receiver optically connected to the fiber input for receiving data from the second optical fiber, and an OTDR optically connected between the transmitter and the fiber output or between the receiver and the fiber input. An energy level detector is also provided between the receiver and the fiber input.Type: ApplicationFiled: November 4, 2009Publication date: May 13, 2010Applicant: Oyster Optics, Inc.Inventor: Peter Snawerdt
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Patent number: 7706697Abstract: The invention relates in particular to an optical regeneration device for a signal carrying an item of information encoded by phase modulation of that signal, that signal being transmitted over an optical network and comprising a temporal succession of optical pulses. The device comprises an optical pulse nonlinear phase shift module, a linear pulse broadening module a linear pulse broadening module, and a module for the linear compensation of the broadening undergone by the pulses in the linear broadening module.Type: GrantFiled: August 26, 2004Date of Patent: April 27, 2010Assignee: France TelecomInventor: Benjamin Cuenot
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Patent number: 7702241Abstract: 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: GrantFiled: December 7, 2006Date of Patent: April 20, 2010Assignee: AlcatelInventor: Gustav Veith
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Patent number: 7701842Abstract: A method of suppressing effects of aliasing in a system for digitally processing a high speed signal having a symbol rate of 1/T. The high speed signal is sampled at a fractional multiple (N) of the symbol rate, wherein 1<N<2, to generate a corresponding sample stream, and filtered using a low-pass filter characteristic having a cut-off frequency corresponding to 1/2T. Phase distortions due to the filtering are compensated by digitally processing the sample stream.Type: GrantFiled: February 13, 2008Date of Patent: April 20, 2010Assignee: Nortel Networks LimitedInventors: Kim B. Roberts, Kuang Tsan Wu, Maurice O'Sullivan, Han Sun
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Publication number: 20100092185Abstract: An optical receiver for receiving a processing modulated optical signal, the optical receiver includes a variable dispersion compensator for receiving the optical signal and for compensating chromatic dispersion of the optical signal in accordance with a predetermined chromatic dispersion value; a demodulator including a delay interferometer for receiving the compensated optical signal and for changing a phase moderation information of the compensated optical signal into an amplitude moderation information, and an optical demodulator for changing the amplitude moderation information of the optical signal into an electrical signal; a data regenerator for extracting a clock from the electric signal and for regenerating data from the electric signal by the use of the clock; and a controller for setting an optical phase to the delay interferometer and for setting the dispersion compensation value to the variable dispersion compensator.Type: ApplicationFiled: October 6, 2009Publication date: April 15, 2010Applicant: Fujitsu LimitedInventor: Nobuyuki Nemoto
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Patent number: 7697847Abstract: An optical transmitter is disclosed including an optical signal source generating a frequency modulated signal encoding data. An optical spectrum reshaper is positioned to receive the frequency modulated signal and converts the frequency modulated signal into a reshaped signal having increased amplitude modulation relative to the frequency modulated signal. A third-order dispersive element is positioned to receive the reshaped signal and is adapted to impose third-order dispersion on the reshaped signal to generate a compensated signal having third-order dispersion effective to compensate for second-order dispersion caused by an optical fiber positioned between the optical transmitter and a receiver.Type: GrantFiled: April 2, 2008Date of Patent: April 13, 2010Assignee: Finisar CorporationInventors: Yasuhiro Matsui, Xueyan Zheng
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Patent number: 7693425Abstract: A system and method for dispersion compensation of an optical signal in a hybrid network includes generating optical traffic in a first set of one or more channels, wherein the traffic in the first set of channels is modulated using a first modulation technique. Optical traffic is generated in a second set of one or more channels, wherein the traffic in the second set of channels is modulated using a second modulation technique. An optical dispersion pre-compensation is applied to the second set of channels. The first set of channels and the second set of channels are combined to form an optical signal, and the optical signal is transmitted over an optical network.Type: GrantFiled: January 11, 2007Date of Patent: April 6, 2010Assignee: Fujitsu LimitedInventors: Olga I. Vassilieva, Takao Naito