Using Dispersion Compensation Optical Fiber (e.g., Dcof) Patents (Class 398/148)
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Patent number: 7577365Abstract: This device for optically regenerating pulses includes a synchronous intensity modulator to provide time synchronization for pulses passing through it and to stabilize intensity fluctuations in the pulses. In addition, it includes noise suppression circuitry in the form of a saturable absorber that is distinct from the synchronous intensity modulator and the intensity fluctuations stabilizer.Type: GrantFiled: April 20, 2004Date of Patent: August 18, 2009Assignee: France TelecomInventor: Erwan Pincemin
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Patent number: 7555220Abstract: An optical equalizer/dispersion compensator (E/CDC) comprises an input/output for receiving a multiplexed channel signal comprising a plurality of channel signals of different wavelengths. An optical amplifier may be coupled to receive, as an input/output, the multiplexed channel signals which amplifier may be a semiconductor optical amplifier (SOA) or a gain clamped-semiconductor optical amplifier (GC-SOA). A variable optical attenuator (VOA) is coupled to the optical amplifier and a chromatic dispersion compensator (CDC) is coupled to the variable optical attenuator. A mirror or Faraday rotator mirror (FRM) is coupled to the chromatic dispersion compensator to reflect the multiplexed channel signal back through these optical components The E/CDC components may be integrated in a photonic integrated circuit (PIC) chip.Type: GrantFiled: October 22, 2004Date of Patent: June 30, 2009Assignee: Infinera CorporationInventors: Stephen G. Grubb, Charles H. Joyner, Frank H. Peters, Fred A. Kish, Jr., Drew D. Perkins
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Publication number: 20090142070Abstract: An example embodiment of the invention includes a method and apparatus for supporting fiber span loss and dispersion measurements in the presence or absence of dispersion compensation elements (DCE). The technique may be used to configure a network link by accessing an optical signal at an ingress side of a connection point for a DCE coupling an egress side of a fiber span at the ingress side of the DCE to an optical amplifier at a connection point for an egress side of the DCE. The technique may include determining chromatic dispersion of the fiber span based on the optical signal and reporting information associated with chromatic dispersion. As a result, the technique may be used, for example, during initial system installation when user data signals and the DCE are not present as well as after the network begins carrying user traffic and after a DCE has been installed.Type: ApplicationFiled: November 29, 2007Publication date: June 4, 2009Applicant: Tellabs Operations, Inc.Inventors: Mark E. Boduch, Kimon Papakos, Julia Y. Larikova
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Patent number: 7538935Abstract: A technique for generating variable pulse delays uses one or more nonlinear-optical processes such as cross-phase modulation, cross-gain modulation, self-phase modulation, four-wave mixing or parametric mixing, combined with group-velocity dispersion. The delay is controllable by changing the wavelength and/or power of a control laser. The delay is generated by introducing a controllable wavelength shift to a pulse of light, propagating the pulse through a material or an optical component that generates a wavelength dependent time delay, and wavelength shifting again to return the pulse to its original wavelength.Type: GrantFiled: March 17, 2006Date of Patent: May 26, 2009Assignee: Cornell Research Foundation, Inc.Inventors: Alexander Gaeta, Jay E. Sharping, Chris Xu
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Patent number: 7536108Abstract: The present invention relates to an automatic dispersion compensating optical link system. Carrier suppressed RZ encoded optical signals generated using carrier suppressing means and binary NRZ code or partial response code, or carrier suppressed clock signals generated using carrier suppressing means and clock signals are transmitted on an optical transmission line. Two bands of the carrier suppressed RZ encoded optical signals or carrier suppressed clock signals transmitted on the optical transmission line are each divided into bands and are received. Phase information of the respective basebands is extracted from the binary NRZ code components or partial response code components or clock signals in each band and the relative phase difference thereof is detected. The chromatic dispersion value of the optical transmission line is then calculated from the relative phase difference.Type: GrantFiled: June 26, 2002Date of Patent: May 19, 2009Assignee: Nippon Telegraph & Telephone CorporationInventors: Akira Hirano, Yutaka Miyamoto, Masahito Tomizawa, Shoichiro Kuwahara, Hiroshi Takahashi, Yasuyuki Inoue
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Patent number: 7515833Abstract: An all optical network for optical signal traffic has at least a first ring with at least one transmitter and one receiver. The first ring includes a plurality of network nodes. At least a first add/drop broadband coupler is coupled to the first ring. The broadband coupler includes an add port and a drop port to add and drop wavelengths to and or from the first ring, a pass-through direction and an add/drop direction. The first add/drop broadband coupler is configured to minimize a pass-through loss in the first ring and is positioned on the first ring.Type: GrantFiled: June 9, 2006Date of Patent: April 7, 2009Assignee: OpVista IncorporatedInventor: Winston I. Way
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Publication number: 20090087190Abstract: A dispersion management system for soliton or soliton-like transmission systems comprises a length of optical fibre (L) in which a plurality of sections (l) made up of components (N, A) of opposite sign dispersions are concatenated together. The duration of the dispersion compensation phase is short in comparison with the propagation interval in the remainder of the system and that the path average dispersion is anomalous.Type: ApplicationFiled: March 31, 2008Publication date: April 2, 2009Inventors: Nicholas John Doran, Nicholas John Smith
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Patent number: 7512346Abstract: An optical fiber system comprising: (i) a dispersion pre-compensator including dispersion compensating fiber DCF characterized by the overall dispersion value DDCF at the operating wavelength ?; and (ii) a passive optical network (PON) including a plurality of transmission paths provided by a plurality of optical fibers, said plurality of transmission paths having a minimum and maximum dispersion value DMIN and DMAX; wherein the dispersion pre-compensator includes an output port operatively coupled to an input port of the a passive optical network and ?DMAX<DDCF<?DMIN.Type: GrantFiled: February 16, 2006Date of Patent: March 31, 2009Assignee: Corning IncorporatedInventors: John Christopher Mauro, Srikanth Raghavan
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Patent number: 7512344Abstract: A dispersion compensator is applicable to a WDM optical transmission system and features low loss, wideband usage, and minimum ripple. The dispersion compensator is constructed so that the light emitted from a collimator will be reflected from an etalon of a 100% single-side reflectance by arranging the etalon and a mirror in parallel or with a slight angle and then enter another collimator. Elements for achieving variable dispersion compensation by changing temperature using a heater, for example, are also provided. In addition, these dispersion compensating elements are provided in multi-stage form and the angle of the mirror and the reflectance of the etalon are optimized. Thus, it becomes possible to realize a dispersion compensator applicable to a WDM optical transmission system and featuring low loss, wideband usage, and minimum ripple.Type: GrantFiled: July 11, 2005Date of Patent: March 31, 2009Assignee: Hitachi Metals Ltd.Inventors: Toshiki Sugawara, Satoshi Makio
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Patent number: 7502565Abstract: A laser filter circuit includes an input terminal configured to receive an input laser signal and a first filter chain configured to generate a filtered signal. The first filter chain is coupled to the input terminal and has one or more filters connected in series. Each filter includes one or more adjustable capacitor networks. An adjustable capacitor controller generates one or more capacitor switch control signals based on an operating frequency of the input laser signal. The one or more control signals are for adjusting the capacitance of the one or more adjustable capacitor networks in the first filter chain. A plurality of output terminal output the filtered signal from the first filter chain.Type: GrantFiled: March 4, 2005Date of Patent: March 10, 2009Assignee: Finisar CorporationInventor: Timothy G. Moran
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Patent number: 7493050Abstract: An optical communication system transmitting a plurality of channel wavelengths is provided. The system includes a transmitter unit, a receiver unit, and an optical transmission path interconnecting the transmitter and receiver units. The transmission path has a concatonation of optical fibers defining a dispersion map such that each of the channel wavelengths are located at FMX and XPM antiresonances at which FWM and XPM are suppressed.Type: GrantFiled: June 3, 2003Date of Patent: February 17, 2009Assignee: Red Sky Subsea, Ltd.Inventor: Stephen G. Evangelides, Jr.
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Patent number: 7483613Abstract: Disclosed are an improved system and a related method for compensating the chromatic dispersion of a given length of a transmission fiber over a given spectral band by employing at least two chromatic dispersion compensating fibers that, with respect to the slope of the slope of the chromatic dispersion (SSi), have values of opposite signs.Type: GrantFiled: November 2, 2007Date of Patent: January 27, 2009Assignee: Draka Comteq B.V.Inventors: Marianne Bigot-Astruc, Louis-Anne De Montmorillon, Denis Molin, Pierre Sillard
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Patent number: 7483614Abstract: There is disclosed an optical fiber wherein an absolute value of the fourth order dispersion ?4 of fourth derivative ?4 of propagation constant ? with respect to angular frequency ? at a mean zero dispersion wavelength ?0 in an overall length is not more than 5×10?56 s4/m and wherein a fluctuation of a zero dispersion wavelength along a longitudinal direction is not more than ±0.6 nm.Type: GrantFiled: September 7, 2006Date of Patent: January 27, 2009Assignee: Sumitomo Electric Industries, Ltd.Inventors: Masaaki Hirano, Tetsuya Nakanishi, Toshiaki Okuno
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Patent number: 7477848Abstract: An optical receiving apparatus sets, efficiently and optimally, a delay interferometer and a variable wavelength dispersion compensator in the apparatus.Type: GrantFiled: December 13, 2005Date of Patent: January 13, 2009Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Akira Miura, Takeshi Hoshida
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Patent number: 7474860Abstract: In an over-sampled maximum-likelihood sequence estimation (MLSE) receiver system, the optimal sample spacing is determined for a variety of conditions. In an illustrative implementation, the system includes an optical filter for tightly filtering an incoming optical data signal with an on-off-keying (OOK) non-return-to-zero (NRZ) format, followed by an optical-to-electrical converter, an electrical filter, a sampler, and a MLSE receiver. The sampler samples the filtered electrical data signal twice each bit period with unequal sample spacings. For wide optical filtering bandwidths, the optimal sample spacing occurs at less than 50% of a bit period. For narrow bandwidths, the optimal sample instances occur closer to the maximum eye opening.Type: GrantFiled: December 19, 2005Date of Patent: January 6, 2009Assignee: Alcatel-Lucent USA Inc.Inventors: Rene Jean Essiambre, Michael Rubsamen, Peter J. Winzer
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Patent number: 7454144Abstract: A process optically transports digital data over an all-optical long-haul communication path. The process includes transporting digital optical data signals at a selected bit rate and a selected wavelength over a sequence of transmission spans. The sequence includes 70 percent or more of the spans of the long-haul all-optical communication path. Each span of the sequence has a primary local maximum optical power point for the wavelength on a transmission fiber and nearest to an input of the span. The transporting causes a cumulative dispersion of each signal to evolve such that residual dispersions per span are positive over some of the spans and are negative over other of the spans. At the primary local maximum power points, magnitudes of cumulative dispersions of the signals in pico seconds per nanometer remain at less than 32,000 times the inverse of the bit rate in giga bits per second.Type: GrantFiled: August 24, 2007Date of Patent: November 18, 2008Assignee: Lucent Technologies Inc.Inventors: Aref Chowdhury, Rene′-Jean Essiambre, Lisa Kathleen Wickham
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Patent number: 7444082Abstract: A method for the adaptive adjustment of a PMD compensator in optical fiber communication systems comprises the steps of taking the signal at the compensator output and extracting the components y1(t) and y2(t) on the two orthogonal polarizations, computing the signal y(t)=[y1(t)]2+[y2(t)]2, sampling the signal y(t) at instants tk=kT with T=symbol interval to obtain samples y(tk), computing the mean square error e(k)=y(tk)?u(k) with u(k) equal to the symbol transmitted, and adjusting the parameters of the compensator to seek to minimize e(k).Type: GrantFiled: December 3, 2002Date of Patent: October 28, 2008Assignee: Ericsson ABInventors: Giulio Colavolpe, Enrico Forestieri, Giancarlo Prati
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Patent number: 7437068Abstract: An optical communication link has a plurality of light emitting elements and a plurality of light receiving elements associated with the respective light emitting elements, and a plurality of optical fibers each for conveying an optical signal emitted from one light emitting element to an associated light receiving element. The optical fibers have respective lengths that include at least two different lengths, and respective transmission losses per unit length that vary according the lengths of the optical fibers, so that variation of the transmission losses among the optical fibers due to difference in optical fiber length is prevented.Type: GrantFiled: September 17, 2002Date of Patent: October 14, 2008Assignee: Sharp Kabushiki KaishaInventors: Yorishige Ishii, Toshihiro Tamura
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Patent number: 7418206Abstract: It is an object of the present invention to provide a control technique for reducing wavelength dependence of wavelength dispersion values and also for suppressing a change in wavelength transmission characteristic with a temperature variation or the like, in a VIPA-type wavelength dispersion compensator.Type: GrantFiled: March 25, 2004Date of Patent: August 26, 2008Assignee: Fujitsu LimitedInventor: Yuichi Kawahata
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Patent number: 7406264Abstract: An optical communications system, comprising a first node, first dispersion compensation fiber located in the first node, wherein the first dispersion compensation fiber induces dispersion onto optical signals passing through the first dispersion compensation fiber, a second node, a plurality of spans between the first and second nodes, and second dispersion compensation fiber located in at least one of the spans, wherein the second dispersion compensation fiber induces dispersion onto optical signals passing through the second dispersion compensation fiber, and wherein the dispersion induced by the second dispersion compensation fiber is opposite in sign to that induced by the first dispersion compensation fiber.Type: GrantFiled: December 19, 2005Date of Patent: July 29, 2008Assignee: Broadwing CorporationInventors: Sandra F. Feldman, C. Kent Gardiner
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Patent number: 7403717Abstract: Method and apparatus for compensating for first-order Polarization Mode Dispersion in an optical transmission system. An apparatus has a polarization controller for transforming polarization components of an optical signal carried by the optical fiber into orthogonal polarization states, a variable delay line for introducing a variable differential time delay between the polarization states and for producing an output optical signal that is compensated for PMD in the optical fiber, and a feedback unit for adjusting the polarization controller and the variable delay line to compensate for variations in the PMD of the optical fiber, the feedback unit including apparatus for generating a plurality of independent control signals to independently control actuators of the polarization controller and the variable delay line. The invention provides for a reduction in response time of the actuators and a reduction in complexity of an algorithm used to control the apparatus.Type: GrantFiled: April 18, 2002Date of Patent: July 22, 2008Assignee: Telefonaktiebolaget LM Ericsson (publ)Inventors: Jean Pierre von der Weid, Luis Carlos Blanco Linares, Giancarlo Vilela de Faria
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Patent number: 7400835Abstract: Chromatic dispersion in a high speed CS-RZ WDM transmission system is reduced by providing tailored “precompensation” for individual and/or groups of optical signals. Such precompensation is achieved by passing the optical signals through a dispersion compensating elements, such as dispersion compensating fiber, within an optical multiplexer, i.e., prior to multiplexing the signals onto a single optical fiber. Additional dispersion compensation can be performed in optical amplifiers and within an optical demultiplexer downstream from the optical multiplexer.Type: GrantFiled: August 30, 2002Date of Patent: July 15, 2008Assignee: Ciena CorporationInventors: Harshad Sardesai, Michael Taylor, Sanjaykumar Upadhyay
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Patent number: 7389047Abstract: The network comprises an optical ring link (F) and a concentrator (HUB) that sends via one end of the link “downlink” optical signals carried by respective wavelengths and receives “uplink” optical signals via the other end of the link. The link is divided into a plurality of segments (FS1-FS4) separated by access nodes (AN1-AN3) for receivers (RX) of downlink optical signals and for senders (TX) of uplink optical signals. Each access node comprises coupling means that are not wavelength-selective for coupling the segment on the upstream side of the node to the segment on the downstream side and to the receivers and to couple the senders (TX) to the segment on the downstream side. The downlink optical signals are carried by wavelengths belonging to a set of predefined wavelengths. To optimize the use of spectral resources, a rejection filter (NF) is inserted into a segment to reject a portion of the wavelengths of said set of wavelengths.Type: GrantFiled: February 22, 2005Date of Patent: June 17, 2008Assignee: AlcatelInventors: Thierry Zami, Arnaud Dupas
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Patent number: 7379677Abstract: The wavelength converter comprises (1) an optical multiplexer for multiplexing an amplitude-modulated first light and reference light, which is continuous light having a wavelength different from the wavelength of the first light, (2) an optical fiber for propagating the multiplexed light therethrough to generate a third light by a non-linear optical phenomenon, and (3) an optical filter having a pass wavelength range set such that a pulse time width of the third light is 20% or more narrower than a pulse time width of the first light after the third light has passed through the optical filter, or (3?) an optical filter having a pass wavelength range set such that a cross point of an eye pattern of the third light is lower than a cross point of an eye pattern of the first light after the third light has passed through the optical filter.Type: GrantFiled: January 26, 2005Date of Patent: May 27, 2008Assignee: Sumitomo Electric Industries, Ltd.Inventor: Toshiaki Okuno
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Patent number: 7376358Abstract: An optical spike is generated at an arbitrarily selected location within an arbitrary optical link. The optical spike is generated by deriving a spike signal having a plurality of components, and launching the spike signal into the a transmitter end of the optical link. An initial phase relationship between the components is selected such that the involved signal components will be phase aligned at the selected location. In order to achieve this operation, the initial phase relationship between the components may be selected to offset dispersion induced phase changes between the transmitter end of the link and the selected location. One or more optical spikes can be generated at respective arbitrarily selected locations within the link, and may be used for performance monitoring, system control, or other purposes.Type: GrantFiled: October 3, 2003Date of Patent: May 20, 2008Assignee: Nortel Networks LimitedInventors: Kim Roberts, Maurice O'Sullivan
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Patent number: 7373087Abstract: Systems and methods for optical communications. In one implementation, a communications device is provided. The communications device includes an Optical domain Adaptive Dispersion Compensation Module (OADCM); an Electrical domain Adaptive Distortion Compensation Module (EADCM); and a controller coupled to, and operable to selectively control, both the OADCM and the EADCM.Type: GrantFiled: February 27, 2004Date of Patent: May 13, 2008Assignee: Oplink Communications, Inc.Inventors: Feng Shi, Genzao Zhang, Xiaoli Fu, Jinghui Li, Tongqing Wang, John Ralston, Moni G. Mathew
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Patent number: 7369777Abstract: A dispersion compensator is provided that includes an input port 102 for receiving a WDM optical signal and a dispersion compensating element 110 coupled to the input port for substantially compensating the WDM optical signal for dispersion that has accumulated along an external transmission path. The dispersion compensator also includes an output port 104 for directing the dispersion compensated WDM optical signal to an external element and a dynamic power controller 106, 108, 112, 114, 116 for maintaining a total power of the WDM signal below a prescribed level prior to receipt of the WDM optical signal by the dispersion compensating element.Type: GrantFiled: November 20, 2003Date of Patent: May 6, 2008Assignee: General Instrument CorporationInventors: Chandra Sekhar Jasti, Hermann Gysel, Mani Ramachandran
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Patent number: 7369778Abstract: In one embodiment of the invention a dispersion compensator is provided for use in a dense wavelength division multiplexed optical communication system. The dispersion compensator comprises a periodic-group-delay dispersion compensation module which provides a portion of the dispersion compensation for a dispersion managed span of the optical communication system. A remaining portion of the dispersion compensation for the dispersion managed span is provided by dispersion compensating fiber. The portions of the dispersion compensation provided by each of the periodic-group-delay dispersion compensation module and the dispersion compensating fiber is selected such that the collision-induced timing jitter is reduced.Type: GrantFiled: December 30, 2002Date of Patent: May 6, 2008Assignee: Lucent Technologies Inc.Inventors: Xiang Liu, Linn Frederick Mollenauer, Xing Wei
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Patent number: 7352971Abstract: A method and system is provided for compensating polarization mode dispersion (PMD) in an optical communications system includes a controller designed to control a broadband PMD compensator to differentially delay light at each one of a plurality of selected wavelengths. At least one of the selected wavelengths lies between an adjacent pair of channel wavelengths of the optical communications system. A performance parameter value indicative of PMD is measured at each channel wavelength of the optical communications system. An estimated performance parameter value is then calculated at each selected wavelength, and an error function calculated as a function of wavelength based on the estimated performance parameter values. The broadband PMD compensator is then controlled to minimize the value of the error function.Type: GrantFiled: August 2, 2002Date of Patent: April 1, 2008Assignee: Nortel Networks LimitedInventors: Kim B. Roberts, Richard D. Habel, Maurice S. O'Sullivan
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Patent number: 7352970Abstract: A dispersion management system for soliton or soliton-like transmission systems comprises a length of optical fiber (L) in which a plurality of sections (I) made up of components (N,A) of opposite sign dispersions are concatenated together. The duration of the dispersion compensation phase is short in comparison with the propagation interval in the remainder of the system and that the path average dispersion is anomalous.Type: GrantFiled: May 26, 1998Date of Patent: April 1, 2008Assignee: BTG International LimitedInventors: Nicholas John Doran, Nicholas John Smith
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Patent number: 7336899Abstract: A method and apparatus for determining the dispersion characteristics of minimum phase filters using substantially only an amplitude response of a minimum phase filter under test includes fitting an amplitude spectrum of the minimum phase filter with a substantially straight line curve, and determining the dispersion characteristics of the minimum phase filter using the straight line curve and the relationships determined by the inventors. Various inventive equations determined by the inventors representative of the relationship between an amplitude response of a minimum phase filter and the dispersion characteristics of the minimum phase filter are used for determining the dispersion characteristics of the minimum phase filter.Type: GrantFiled: June 9, 2003Date of Patent: February 26, 2008Assignee: Lucent Technologies Inc.Inventors: Gadi Lenz, Magaly Spector
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Patent number: 7330663Abstract: A multi-channel (e.g. WDM) receiver, in which l PMD compensators are time-shared by n (n>1) communication channels, where 1?l?n?1. The receiver implements PMD monitoring to identify channels exhibiting relatively high amounts of PMD. Some or all of the identified channels are then subjected, before decoding, to PMD-reduction processing, while the remaining channels are decoded without such processing. Channel allocation for the processing may be changed dynamically depending on the current amounts of PMD exhibited by various channels. Due to efficient utilization of PMD compensators, multi-channel receivers of the invention are capable of performance comparable to that of the corresponding fully compensated (i.e., having a dedicated PMD compensator for each channel) receivers, but at appreciably lower cost.Type: GrantFiled: April 29, 2003Date of Patent: February 12, 2008Assignee: Lucent technologies Inc.Inventors: Randy C. Giles, Xiang Liu, Chongjin Xie
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Patent number: 7324758Abstract: An optical dispersion monitoring apparatus and an optical dispersion monitoring method are capable of monitoring dispersion accurately with a simple construction in an optical transmission system using the same. To this end, the optical dispersion monitoring apparatus includes a light receiving section converting an input optical signal into an electrical signal, a signal transition position detecting section detecting the voltage level of a waveform of the output signal from the light receiving section, at a crossing point of a rising edge and a falling edge, and a cumulative dispersion information extracting section comparing the voltage level at the crossing point with a reference signal to extracts cumulative dispersion information.Type: GrantFiled: November 20, 2003Date of Patent: January 29, 2008Assignee: Fujitsu LimitedInventors: Masazumi Marutani, Takuji Yamamoto
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Patent number: 7321731Abstract: Systems and methods are disclosed herein to provide various optical techniques. For example, in accordance with an embodiment of the present invention, a pulse position modulation discriminator architecture is disclosed for discriminating temporal positions of PPM-encoded optical pulses by converting them from time modulated to frequency modulated signals. As another example, time division multiplexed optical signals may be translated to wavelength division multiplexed optical signals. One or more of the architectures disclosed herein may be implemented, for example, to provide PPM to FM or time to wavelength conversion for receiver or transmitter applications.Type: GrantFiled: April 7, 2004Date of Patent: January 22, 2008Assignee: The Boeing CompanyInventors: Stanislav I. Ionov, Thomas W. Ball, Peter Chu, William S. Hoult, Jr.
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Patent number: 7302176Abstract: A medium-scale IP telecommunications network is configured in a low-cost optical network with good reliability and expandability. A physical configuration example has a center node 2-1 and eight local nodes 2-11 through 2-18 connected in one OADM ring 2-21/2-22. The logical configuration is a star configuration with the central node 2-1 at its origin with all traffic passing through the center node 2-1. The local nodes 2-11 through 2-18 are connected to the central node 2-1 by wavelength-unit optical channels or optical paths ?1 through ?8. Channels are added as required. Initially, for example, the center node 2-1 and the local node 2-5 are connected by ?5, but ?13 can added when the need arises. Since the logical star network is limited to approximately two add/drop optical channels at local nodes, costs are reduced by using inexpensive filters (e.g., dielectric interference film filters or fiber Bragg reflectors) that are capable of extracting only the specific wavelength of the optical channel.Type: GrantFiled: May 26, 2004Date of Patent: November 27, 2007Assignee: Hitachi, LtdInventors: Shinji Sakano, Yasushi Sawada, Hideaki Tsushima, Yoshiaki Ikoma
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Patent number: 7292790Abstract: A method and system for compensating residual dispersion curvature in an optical communication network is disclosed. One embodiment employs two types of dispersion compensating fiber to reduce higher order terms in a residual dispersion profile. The two types of dispersion compensating fiber may be co-located in a dispersion compensation module positioned in each transmission fiber link. Alternatively, the two types of dispersion compensating fiber may be distributed across a span of the optical communication network.Type: GrantFiled: August 9, 2002Date of Patent: November 6, 2007Assignee: Ciena CorporationInventor: Harshad P. Sardesai
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Patent number: 7280765Abstract: A process optically transports digital data over an all-optical long-haul communication path. The process includes transporting digital optical data signals at a selected bit rate and a selected wavelength over a sequence of transmission spans. The sequence includes 70 percent or more of the spans of the long-haul all-optical communication path. Each span of the sequence has a primary local maximum optical power point for the wavelength on a transmission fiber and nearest to an input of the span. The transporting causes a cumulative dispersion of each signal to evolve such that residual dispersions per span are positive over some of the spans and are negative over other of the spans. At the primary local maximum power points, magnitudes of cumulative dispersions of the signals in pico seconds per nanometer remain at less than 32,000 times the inverse of the bit rate in giga bits per second.Type: GrantFiled: December 5, 2003Date of Patent: October 9, 2007Assignee: Lucent Technologies Inc.Inventors: Aref Chowdhury, Rene′-Jean Essiambre, Lisa Kathleen Wickham
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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: 7254342Abstract: A method is provided for transmitting information in an optical communication system that includes transmitting an optical information signal at a wavelength over an optical link with a first and second end. The optical information signal is pre-distorted for dispersion proximate the first end of the optical link. The optical information signal is then compensated proximate the second end of the optical link for dispersion, wherein the pre-distortion and the compensation have opposite polarity at the transmitting wavelength.Type: GrantFiled: October 29, 2003Date of Patent: August 7, 2007Assignee: Fujitsu LimitedInventors: Kaori Odate, Olga I. Vassilieva, Takeshi Hoshida
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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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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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Patent number: 7233727Abstract: This invention relates to an optical fiber and others having a structure for efficiently generating SC light while realizing high nonlinearity over a wide band. The optical fiber has at least a center core region, and an outside cladding region having a refractive index lower than that of the center core region and provided on an outer periphery of the center core region. The optical fiber has, as characteristics to light of a wavelength ?1 in a wavelength range of 1520 nm to 1620 nm, a chromatic dispersion of ?2 ps/nm/km to +2 ps/nm/km, a dispersion slope of ?0.009 ps/nm2/km to +0.009 ps/nm2/km, and a fourth-order dispersion of ?1.8×10?4 ps/nm3/km to +1.8×10?4 ps/nm3/km.Type: GrantFiled: July 11, 2006Date of Patent: June 19, 2007Assignee: Sumitomo Electric Industries, Ltd.Inventors: Masaaki Hirano, Tetsuya Nakanishi, Toshiaki Okuno
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Patent number: 7209654Abstract: A plurality of optical repeaters are provided on a transmission line between an optical transmitting station and an optical receiving station. A combined transmission line section is provided between optical repeaters. The combined transmission line section is composed of the first optical fiber, which is a positive-dispersion fiber, and the second optical fiber, which is a negative-dispersion fiber. Signal light is inputted to the first optical fiber in each combined transmission line section. Each optical repeater inputs pump light to the second optical fiber.Type: GrantFiled: September 26, 2001Date of Patent: April 24, 2007Assignee: Fujitsu LimitedInventors: Toshiki Tanaka, Takao Naito
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Patent number: 7200333Abstract: An optical communication apparatus performs wavelength division multiplexing with respect to signals of a plurality of signal transmission bands. The apparatus includes a first optical unit which effects distributed Raman amplification and has a characteristic that compensates for dispersion of a transmission path to which the optical communication apparatus is connected, with respect to at least one of the signal transmission bands.Type: GrantFiled: September 26, 2001Date of Patent: April 3, 2007Assignee: Fujitsu LimitedInventors: Toru Katagiri, Hiroaki Tomofuji, Hiroshi Onaka
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Patent number: 7187868Abstract: A WDM system includes a transmission station, a receiving station, a first optical path and a second optical path. The first optical path includes a first section and a second section, the second section being capable of compensating at least partially the dispersion accumulated by a series of optical channels along the first section. The series of channels includes at least a first plurality of channels having an average dispersion of the same sign in the first optical path. The system also includes at least a first conversion device, capable of inverting the spectrum and modifying the wavelength of at least the first plurality of channels, to produce a second plurality of channels having an average chromatic dispersion of the same sign in the second optical path.Type: GrantFiled: July 29, 2002Date of Patent: March 6, 2007Assignee: Pirelli Cavi E Sistemi S.p.A.,Inventors: Fabrizio Carbone, Luciano Socci, Marco Romagnoli
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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: 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: 7171089Abstract: Enhancement of the supercontinuum generation performance of a highly-nonlinear optical fiber (HNLF) is accomplished by performing at least one post-processing treatment on the HNLF. Particularly, UV exposure of the HNLF will modify its dispersion and effective area characteristics so as to increase its supercontinuum bandwidth, without resorting to techniques such as tapering or introducing unwanted reflections into the HNLF. The UV exposure can be uniform, slowly varying or aperiodic along the length of the HNLF, where the radiation will modify the nonlinear properties of the HNLF. Various other methods of altering these properties may be used. The output from the HNLF can be monitored and used to control the post-processing operation in order to achieve a set of desired features in the enhanced supercontinuum spectrum.Type: GrantFiled: February 22, 2005Date of Patent: January 30, 2007Assignee: Fitel USA Corp.Inventors: Kenneth S. Feder, Jeffrey W. Nicholson, Paul S. Westbrook
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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