Reducing Distortion Or Dispersion Patents (Class 398/159)
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Patent number: 8107826Abstract: A method of communicating digital information over a dispersive optical channel includes encoding the digital information into a plurality of data blocks, each of which includes a number of bits of the information. A time-varying electrical signal is generated which corresponds with each of said data blocks. The time-varying electrical signal is applied to an optical transmitter (122) to generate an optical signal which includes an asymmetrically amplitude limited transmitted signal modulated onto an optical carrier. The optical signal is then transmitted over the dispersive optical channel (106). At a receiving apparatus (104) the optical signal is detected to produce an electrical signal which corresponds with the asymmetrically amplitude limited transmitted signal.Type: GrantFiled: September 1, 2006Date of Patent: January 31, 2012Assignee: Ofidium Pty Ltd.Inventors: Jean Armstrong, Arthur James Lowery
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Patent number: 8098991Abstract: A method is provided for co-site interference mitigation in an RF communication system. Spectral nulls created in an optical domain may be used to mitigate interfering signals in an RF signal. The method includes: receiving an RF input signal via an antenna; generating two optical signals that are each modulated using the RF signal; creating a phase delay in one of the two optical signals that corresponds with a spectral null at a frequency of an interfering signal; converting the two optical signals into two corresponding electrical signals and combining the two electrical signals to create spectral nulls via interference between the two signals and form a mitigated output signal. In this way, the spectral null offsets the amplitude of the interfering signal, thereby reducing the signal strength of the interfering signal.Type: GrantFiled: August 20, 2008Date of Patent: January 17, 2012Assignee: Harris CorporationInventors: Richard DeSalvo, Charles Middleton, Michael Borbath, Jeffrey A. Wyatt
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Patent number: 8095020Abstract: According to an aspect of an embodiment, an apparatus includes: a wavelength-to-transmission quality characteristic obtaining unit for obtaining a wavelength-to-transmission quality characteristic; a residual dispersion-to-transmission quality characteristic saving unit for saving a residual dispersion-to-transmission quality characteristic; a wavelength-to-residual dispersion characteristic generating unit for generating a wavelength-to-residual dispersion characteristic from a relationship between the wavelengths of the other channels and the residual dispersion based on the wavelength-to-transmission quality characteristic and the residual dispersion-to-transmission quality characteristic; a variable dispersion compensator for providing variable dispersion compensation to another channel,; and a variable dispersion compensation controlling unit for performing setting control on a dispersion compensation amount.Type: GrantFiled: October 10, 2008Date of Patent: January 10, 2012Assignee: Fujitsu LimitedInventor: Kentaro Nakamura
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Publication number: 20120002971Abstract: A polarization-tracking device having a waveguide grating that serves as a polarization splitter and an optical fiber-to-waveguide coupler. The polarization-tracking device also has an optical mixing circuit configured to receive light from the waveguide grating and a control circuit for tuning the optical mixing circuit. Based on an optical feedback signal received from the optical mixing circuit, the control circuit can configure the latter to produce two optical output signals that represent, e.g., two independently modulated polarization components of a polarization-multiplexed optical input signal or two principal states of polarization of an optical input signal that has been subjected to polarization-mode dispersion. Certain embodiments of the polarization-tracking device lend themselves to convenient implementation in a photonic integrated circuit and are configurable to provide endless polarization control.Type: ApplicationFiled: June 30, 2010Publication date: January 5, 2012Applicant: ALCATEL-LUCENT USA INC.Inventor: Christopher R. Doerr
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Publication number: 20110318019Abstract: The present disclosure is directed to managing dispersion compensation in optical transmission line utilizing single mode fiber with no in-line dispersion compensation. A communication system terminal includes one or more dispersion compensation modules configured to compensate for at least a portion of optical dispersion associated with optical data signals supplied from the transmission line. A receiver communicatively coupled to the transmission line includes a digital signal processor configured to compensate for an additional portion of dispersion associated with the optical data signals converted to electrical signals by the receiver.Type: ApplicationFiled: June 29, 2010Publication date: December 29, 2011Applicant: Tyco Electronics Subsea Communication LLCInventors: Morten Nissov, Alexei Pilipetskii, Neal Bergano
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Publication number: 20110311233Abstract: The present application is directed to an apparatus and method for the automated compensation of dispersion over a broad wavelength range for coherent optical pulses. In one embodiment, the present application discloses an automatic dispersion compensating optical apparatus configured to change chirp introduced into an optical signal by an optical system in optical communication with the dispersion compensating optical apparatus and includes at least one wavelength-tunable source of coherent optical pulses configured to output at least one optical signal, at least one dispersion compensation device configured to receive the optical signal from the coherent source, and at least one controller in communication with the dispersion compensation device and configured to adjust chirp introduced into the optical signal by the dispersion compensation device as the wavelength of the optical signal is varied.Type: ApplicationFiled: May 19, 2011Publication date: December 22, 2011Inventors: Dmitri A. Oulianov, Stefan Marzenell, Richard Boggy
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Patent number: 8073334Abstract: The present invention relates to an optical modulation method and optical modulation system of a wavelength locked Fabry Perot-Laser Diode (FP-LD) by injecting a broadband light source (BLS) using mutual injection of FP-LDs. More specifically, the present invention relates to a novel modulation technology which embodies a wavelength locked FP-LD capable of being used as an economic light source in an optical network based on a wavelength-division multiplexing passive optical network (WDM-PON).Type: GrantFiled: November 8, 2005Date of Patent: December 6, 2011Assignee: Korea Advanced Institute of Science and TechnologyInventors: Chang-Hee Lee, Ki-Man Choi
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Patent number: 8064767Abstract: The present invention provides a system and method of optical communications that utilize coherent detection technique and optical orthogonal frequency division multiplexing for phase encoded data transmission. In particular the invention addresses a device and method for digital polarization compensation of optical signals with up to 100 Gb/s transmission rate received via an optical link. The polarization compensation operates in two modes: acquisition mode and tracking mode. The polarization recovery is performed at the receiver side using the received digital signal conversion into frequency domain and separate reconstruction of the polarization state in each spectral component.Type: GrantFiled: March 11, 2008Date of Patent: November 22, 2011Assignee: CeLight, Inc.Inventors: Isaac Shpantzer, Alexander Genusov, Yehouda Meiman, Jacob Khurgin
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Patent number: 8059965Abstract: Methods and systems for PMD compensation in an optical communication system are implemented by transmitting multiple optical signals through a common optical conduit to an optical compensator that adjustably rotates the polarization states of the multiple optical signals and transmits the rotated optical signals to an optical receiver. The receiver, upon sensing an excessive error condition, commands the optical compensator to change the polarization state of rotation, which changes the PMD profile of the received optical signals.Type: GrantFiled: December 2, 2008Date of Patent: November 15, 2011Assignee: AT&T Intellectual Property II, L.P.Inventors: Michael Herbert Eiselt, Jonathan A. Nagel
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Patent number: 8045856Abstract: The present disclosure provides polarization mode dispersion compensation (PMDC) and polarization de-multiplexing systems and methods for polarization multiplexed (PolMux) optical transmission systems. The PMDC detects an error signal before a polarization splitter in PolMux systems for controlling polarization controllers (PC) and/or DGDs in the PMDC for return-to-zero (RZ) differential m-phase shift keying (DmPSK) signals. For bit-aligned PolMux systems, the error signal could be the level of clock frequency at one, two, or more times of the baud rate at one polarization. For bit-interleaved PolMux systems, the error signal could be the level of clock frequency at two times of the baud rate at one polarization. The PMDC can operate in PolMux systems with any arbitrary time offset between the two polarizations. The polarization de-multiplexer utilizes error detection at both output arms of a polarization splitter to mitigate PDL impact on any PolMux type of signal.Type: GrantFiled: October 31, 2008Date of Patent: October 25, 2011Assignee: Ciena CorporationInventors: Yunfeng Shen, Shan Zhong, Harshad Sardesai
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Patent number: 8045861Abstract: A method and system for spectral suppression of a noise in a communication signal. The method includes transmitting a communication signal through a plurality of rejection filters to create a plurality of spectral holes over a spectrum of the communication signal. The communication signal with an acquired noise is received. Noise intensities of the acquired noise at the plurality of spectral holes are measured, and the acquired noise over the spectrum of the communication signal is calculated. The acquired noise is subtracted from the communication signal with the acquired noise.Type: GrantFiled: November 17, 2006Date of Patent: October 25, 2011Assignee: HRL Laboratories, LLCInventor: Oleg M. Efimov
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Patent number: 8044812Abstract: A wireless sensor network including a receiver including a photodetector, and a sensor node that includes a sensor configured to sense a property, a transmitter configured to emit outgoing optical energy, the outgoing optical energy being indicative of the property, and a photodetector configured to harvest incoming optical energy and convert the incoming optical energy into electrical energy useful by the transmitter, wherein the photodetector of the receiver is positioned to receive the outgoing optical energy.Type: GrantFiled: January 12, 2009Date of Patent: October 25, 2011Assignee: The Boeing CompanyInventor: Daniel N. Harres
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Patent number: 8041226Abstract: An optical transceiver and a method to setup the optical transceiver are disclosed, where the transceiver has a function to compensate the distortion and the dispersion due to the limited bandwidth of the electrical signal line, that of the active devices, and that of the optical fiber. The optical transceiver comprises a transmitter with an equalizer unit and a receiver also with an equalizer unit. The equalizer unit in the transmitter compensates the distortion due to the limited bandwidth of the transmission lines for the electrical signal and that of the semiconductor active device, while, the equalizer unit in the receiver compensates the dispersion due to the limited bandwidth of the optical fiber.Type: GrantFiled: July 28, 2008Date of Patent: October 18, 2011Assignee: Sumitomo Electric Industries, Ltd.Inventor: Takatoshi Kato
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Publication number: 20110249979Abstract: A tunable dispersion compensator (TDC) is tuned from a first dispersion setpoint to a second dispersion setpoint while maintaining continuity of the dispersion.Type: ApplicationFiled: April 9, 2010Publication date: October 13, 2011Inventors: Lan Sheng, Aaron Zilkie, Mark Summa, Timothy Kent Zahnley, Peter G. Wigley
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Patent number: 8036536Abstract: An optical transmitter apparatus for use in an optical communications network has a polarization dithering unit, an optical transmitter unit, and a transmission fiber. The polarization dithering unit is connected in series between an output of the optical transmitter unit and the transmission fiber.Type: GrantFiled: May 23, 2008Date of Patent: October 11, 2011Assignee: Ericsson ABInventors: Ernesto Ciaramella, Emma Matarazzo
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Patent number: 8027585Abstract: The present invention relates to controlling wavelength switching in a plurality of nodes that are provided to increase the distance of signal transmission in inverse MUX transmission in which a high-speed line is divided into a plurality of low-speed lines for transmission. A maximum skew occurring between adjacent nodes is measured, and switching of wavelength channels is performed in one or a plurality of nodes on the basis of the measured maximum skew to keep the skew of the entire inverse MUX transmission system at or below a prescribed value. The optical communication device is provided with an NNI functional block to which high-speed lines on the transmission channel side are connected, and a UNI functional block to which low-speed lines on the client side are connected.Type: GrantFiled: March 31, 2006Date of Patent: September 27, 2011Assignee: NEC CorporationInventor: Yoshitaka Yokoyama
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Patent number: 8023402Abstract: 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: December 21, 2009Date of Patent: September 20, 2011Assignee: Ciena CorporationInventors: Kim B. Roberts, Kuang Tsan Wu, Maurice O'Sullivan, Han Sun
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Patent number: 8014668Abstract: A method and apparatus for distributed measurement of chromatic dispersion in an optical network is disclosed. The network comprises optical switching nodes interconnected by optical links. An optical link may comprise multiple spans, each span ending in a transport module which comprises signal-processing components. At least one optical switching node has a probing signal generator transmitting an optical probing signal along a selected path in the network. Probing-signal detectors placed at selected transport modules determine chromatic-dispersion values and send results to a processing unit which determines appropriate placement of compensators or appropriate adjustments of compensators placed along the path. A preferred probing signal has the form of wavelength modulated optical carrier which is further intensity modulated by a periodic, preferably sinusoidal, probing tone.Type: GrantFiled: January 20, 2008Date of Patent: September 6, 2011Assignee: Alcatel LucentInventors: Ping Wai Wan, Derrick Remedios, Patrick Chilufya Chimfwembe, Colin Geoffrey Kelly, James Benson Bacque
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Patent number: 8014680Abstract: An optical transceiver which can effectively reduce optical output jitter when an error is made during designing and manufacturing of a printed circuit board (PCB), and a method of controlling optical output jitter using the optical transceiver are provided. The optical transceiver includes a transmitter unit including an equalizing (EQ) filter which can reduce jitter of a high speed electric signal; a control circuit which controls the EQ filter; a receiver unit which receives an optical signal; and a micro-controller which controls the transmitter unit and the receiver unit.Type: GrantFiled: November 5, 2007Date of Patent: September 6, 2011Assignee: Electronics and Telecommunications Research InstituteInventors: Joon Ki Lee, Jyung Chan Lee, Kwangjoon Kim
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Patent number: 8009995Abstract: A method and apparatus for receiving a digital signal having a plurality of significant bits of resolution. The apparatus includes a mode locked laser comprising a single output. The apparatus also includes a beam divider operable to receive the single output. The apparatus also includes a plurality of optical modulators operable to communicate with said beam divider and operable to receive a respective plurality of signals corresponding to a plurality of significant bits of resolution. Optionally, the apparatus also includes a source operable to output a digital waveform with the plurality of signals corresponding to the plurality of significant bits of resolution of the digital waveform, the plurality of signals operable to drive the plurality of optical modulators.Type: GrantFiled: September 27, 2006Date of Patent: August 30, 2011Assignee: The United States of America as represented by the Secretary of the NavyInventors: Currie Marc, Lou W. Janet
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Publication number: 20110206382Abstract: The invention relates to a method and an apparatus for distortion compensation of signals transmitted via a bidirectional link between a client device and a host device, said method comprising the steps of performing a post-distortion-compensation for an upstream signal received by the host device on said bidirectional link by adjusting post-compensation parameters of a post-compensation unit of said host device and transforming the adjusted post-compensation parameters into pre-compensation parameters of a pre-compensation unit of said host device which performs a pre-distortion compensation for a downstream signal transmitted by said host device via said bidirectional link to said client device.Type: ApplicationFiled: December 16, 2010Publication date: August 25, 2011Inventor: Michael Elselt
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Patent number: 8005375Abstract: A simplified optical receiver architecture capable of tracking and demultiplexing polarization-multiplexed signals, dynamically compensating for PMD using a variety of polarization controller technologies, and reducing the number of delay line demodulators by two for both DPSK and DQPSK modulation is illustrated. Once polarization is stabilized at the first stage of the cascaded system of the present invention, subsequent stages can be simplified and cost reduced.Type: GrantFiled: December 10, 2010Date of Patent: August 23, 2011Assignee: Ciena CorporationInventor: Michael Frankel
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Patent number: 8005360Abstract: A feedback signal indicative of the average RF power of an APol-DPSK optical signal is used by a PMD compensator to adjust the amount of compensation applied to the optical signal.Type: GrantFiled: August 5, 2008Date of Patent: August 23, 2011Assignee: Alcatel LucentInventor: Chongjin Xie
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Patent number: 7995921Abstract: Embodiments of the present invention provide an array of semiconductor optical amplifiers, within a photonic integrated circuit (hereinafter, “PIC”), that apply a gain to one or more optical bands within a WDM signal. According to various embodiments of the invention this array of SOAs can function as both an amplifier and a ROADM by adjusting the gain characteristics of one or more of the SOAs within the array. A band within the WDM signal may be blocked by adjusting the SOA, corresponding to the particular band, to attenuate the band below a threshold.Type: GrantFiled: August 2, 2007Date of Patent: August 9, 2011Assignee: Infinera CorporationInventor: Stephen G. Grubb
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Patent number: 7991295Abstract: A method is provided for dispersion compensation of an optical signal communicated in an optical network comprising a plurality of spans of low chromatic dispersion fiber. The method includes receiving an optical signal comprising a plurality of channels, where the information communicated in a first set of one or more of the channels is modulated using a first modulation technique and where the information communicated in a second set of one or more of the channels is modulated using a second modulation technique. The method also includes uniformly undercompensating for optical dispersion in the optical signal across all of the channels of the optical signal such that the accumulated dispersion in the optical signal increases with each span over which the optical signal is communicated. In particular embodiments, all of the channels of the optical signal are uniformly undercompensated in the range of approximately 60% to approximately 85% dispersion compensation for each span.Type: GrantFiled: March 13, 2008Date of Patent: August 2, 2011Assignee: Fujitsu LimitedInventors: Olga I. Vassilieva, Susumi Kinoshita
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Publication number: 20110176805Abstract: A reconfigurable wavelength selective dispersion compensation device RWSDCD for selective compensation of dispersion in optical channels having different wavelengths. The RWSDCD comprises a controllable wavelength selective unit WSU having a plurality of local, wavelength related input/output (I/O) ports. The RWDSD also comprises a dispersion compensation cascade comprising at least one chain of successively connected dispersion compensation units DCUs, wherein one or more of the DCUs in the chain are respectively connectable to one or more of the local I/O ports. The RWSDCD outputs one or more of the incoming optical channels upon selectively compensating chromatic dispersion in them, by controllably passing these channels via one or more DCUs of the dispersion compensation cascade.Type: ApplicationFiled: September 15, 2009Publication date: July 21, 2011Inventors: Uri Mahlab, Avi Levy
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Patent number: 7983564Abstract: A wavelength division multiplexing system according to the present art adjusts the amount of dispersion compensation (the amount of dispersion compensation of an NZ-DSF and a DCF) every all spans on the basis of the time slot when an intensity modulation signal transmitter outputs an intensity modulation signal and the wavelength interval when a wavelength coupler multiplexes a phase modulation signal (output from a phase modulation signal transmitter) and the intensity modulation signal.Type: GrantFiled: January 31, 2008Date of Patent: July 19, 2011Assignee: Fujitsu LimitedInventors: Hiroki Ooi, Akira Miura, Takeshi Hoshida, Kentaro Nakamura, Yasushi Sugaya, Ryosuke Goto
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Patent number: 7983567Abstract: The invention relates to a method and a system for controlling a PMD compensator (2). For this purpose, a measuring signal (MS) is branched off from an already compensated optical data signal (ODSK) and supplied to a polarization adjuster (2). The output signal of the latter is supplied to an optical filter unit (61) and subdivided into two optical measuring signal components (OMK1, OMK2) having different polarizations. After a respective opto-electrical conversion, the spectra are compared with each other in an analysis and control unit (81) and the PMD compensator (2) is adjusted in such a manner that they are as identical as possible.Type: GrantFiled: June 20, 2006Date of Patent: July 19, 2011Assignee: Nokia Siemens Networks GmbH & Co. KGInventor: Erich Gottwald
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Patent number: 7978982Abstract: An electronic dispersion compensation (EDC) system may comprise one or more EDC solution application modules. The EDC system may include a solution transition module. The solution transition module may be configured to determine a path between a first EDC solution performed by a first EDC solution application module and a second EDC solution performed by a second EDC solution application module. The solution transition module may be configured to provide transition instructions to an EDC solution application module. The transition instructions may include one or more intermediate EDC solutions disposed along a path between a first EDC solution and a second EDC solution.Type: GrantFiled: September 25, 2007Date of Patent: July 12, 2011Assignee: Finisar CorporationInventor: Lucy G. Hosking
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Patent number: 7974541Abstract: A filter conducts the round trip by using the return optical signal that has been shifted in frequency, and measures the transmission optical signal and the return signal in phase by the principle of the Michelson interferometer at the same time, independently, and splits the two optical signals. A polarization state in which transmission and reception optical signals within an optical phase shifter which enters one route of the two optical signals are made orthogonal to each other is provided, to thereby distinguish the transmission and reception signals of the round trip from each other. The light is allowed to pass the shifter in incoming and returning to remove the polarization rotation of the shifter by using the reversibility of the light. Then, the phases of the transmission signal and the return signal are measured and synchronized with each other to conduct the transmission phase compensation.Type: GrantFiled: June 4, 2008Date of Patent: July 5, 2011Assignee: National Institutes of Natural SciencesInventor: Hitoshi Kiuchi
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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: 7929862Abstract: After implementing a scrambler upon an electric signal of digital signals to be transmitted to a user terminal, this electric signal is converted into a digital optical signal, and an analog optical signal and this digital optical signal are multiplexed by wavelength division multiplexing, thereby reducing influence of cross-talk interference that is exerted on the analog optical signal by the digital optical signal.Type: GrantFiled: January 31, 2005Date of Patent: April 19, 2011Assignee: Fujitsu LimitedInventors: Katsuhiko Hakomori, Hiroshi Nishimoto, Akihiko Ichikawa
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Patent number: 7925170Abstract: A predistortion circuit provides a predistorted input signal that compensates for distortion generated by a non-linear amplifier such as a laser device. The predistortion circuit may be used in an optical transmitter designed for broadband applications, such as a laser transmitter used for forward path CATV applications. The predistortion circuit may include a primary signal path and a secondary signal path that receive an input signal. A second order distortion generator on the secondary signal path generates predistortion of a magnitude corresponding to the magnitude of, but at an opposite phase to, the distortion generated by the non-linear amplifier. The second order distortion generator includes diodes with an adjustable diode bias to control phase, magnitude and/or magnitude/phase versus frequency of the predistortion.Type: GrantFiled: August 7, 2007Date of Patent: April 12, 2011Assignee: Applied Optoelectronics, Inc.Inventor: Brian Ishaug
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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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Patent number: 7917036Abstract: An optical transceiver is provided which includes: a bi-directional optical subassembly; a printed circuit board which transmits and receives light for the bi-directional optical subassembly; and an outer casing which covers the bi-directional optical subassembly and the printed circuit board. The bi-directional optical subassembly includes: a laser diode; a photodiode; a stem on which to laser diode and the photo diode are mounted; a cap, which cooperates with the stern to seal the laser diode and the photodiode; and a crosstalk reducing structure for reducing optical and/or electric crosstalk. The crosstalk reducing structure may include a layer which is formed on an inner surface of the cap and is able to absorb an infrared ray.Type: GrantFiled: August 27, 2008Date of Patent: March 29, 2011Assignee: Fujikura Ltd.Inventors: Teijiro Ori, Koichiro Masuko
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Publication number: 20110052193Abstract: A network design apparatus includes an input unit configured to receive network information that indicates nodes connected by optical transmission paths and path information that indicates paths between the nodes; an design unit configured to perform, based on the network information and the path information, wavelength dispersion compensation design using a constraint condition that a path whose span count is larger than a span count of another path that does not satisfy a transmission condition does not satisfy the transmission condition; and an output unit configured to output a result obtained by the design unit.Type: ApplicationFiled: August 17, 2010Publication date: March 3, 2011Applicant: FUJITSU LIMITEDInventors: Yutaka TAKITA, Toru KATAGIRI, Tomohiro HASHIGUCHI, Kazuyuki TAJIMA
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Patent number: 7889995Abstract: A system and method for in-service optical dispersion determination are provided. Optical dispersion is determined by splitting a first optical signal into two components, introducing a time delay between the two components such that corresponding pulses of the two components partially overlap, combining the two components to generate a combined optical signal comprising a first component and a second component, determining power of the combined optical signal while applying a plurality of dispersion compensation values, in order to determine a dispersion compensation value that results in a minimum detected power of the combined optical signal. Polarization Mode Dispersion is determined by adjusting the time delay that is introduced until the power of the combined optical signal is substantially equal for all of the plurality of dispersion compensation values.Type: GrantFiled: August 27, 2007Date of Patent: February 15, 2011Assignee: BTI Systems Inc.Inventors: Lijie Qiao, Ahmad Atieh, John Mills
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Publication number: 20110032619Abstract: A tunable chromatic dispersion compensation device used to compensate chromatic dispersion of wavelength of at least one predetermined wavelength band of light signal is provided. The tunable chromatic dispersion compensation device comprises a chromatic dispersion compensator, and a controller. The chromatic dispersion compensator comprises at least a first chromatic dispersion compensation unit and a second chromatic dispersion compensation unit connected with the first chromatic dispersion compensation unit in series. The first chromatic dispersion compensation unit has a free spectral range, the second chromatic dispersion compensation unit has a free spectral range same as to that of the first chromatic dispersion compensation unit. Each chromatic dispersion compensation unit comprises an interference cavity. The controller comprises an inputting unit being configured for inputting a predetermined chromatic dispersion compensation information.Type: ApplicationFiled: November 19, 2009Publication date: February 10, 2011Applicant: O-NET COMMUNICATIONS (SHENZHEN) LIMITEDInventors: Zeqin Wang, Guohui Zheng, Jun Huang, Xiaobing Qiu
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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: 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: 7877017Abstract: In an optical waveform measurement system, a phase comparator compares phases between an electric signal output from a PD and an electric signal output from a mixer, and outputs a signal having an amplitude proportional to the phase difference of the two electric signals to a VCO via an LPF, as an error signal. A BPF removes a jitter from the electric signal output from the VCO, and a sampling pulse light source outputs sampling light based on the electric signal with the jitter removed. An optical sampling gate samples signal light to be measured with sampling light output from a sampling pulse light source, and the sampled signal light to be measured is measured by an oscilloscope.Type: GrantFiled: February 21, 2008Date of Patent: January 25, 2011Assignee: Fujitsu LimitedInventors: Fumio Futami, Shigeki Watanabe
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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: 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: 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: 20100329695Abstract: The present disclosure relates to dispersion slope compensation and dispersion map management systems and methods in an optical network utilizing a reconfigurable optical add-drop multiplexer (ROADM) with a plurality of different values of dispersion compensation modules (DCMs). The DCMs form a dispersion compensation ladder at certain intermediate nodes in the optical network to provide dispersion slope compensation and dispersion map management. The reconfigurable routing structure of the ROADM enables these intermediate nodes to route individual wavelengths to any one of the DCMs as required for the particular path of the wavelength. Advantageously, the present invention removes the requirement for banded compensation at receiver nodes and allows for dispersion map management at intermediate points along a fiber route as opposed to bulk compensation at the receiver.Type: ApplicationFiled: June 25, 2009Publication date: December 30, 2010Inventor: Balakrishnan SRIDHAR
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Publication number: 20100329694Abstract: The present disclosure provides electrical domain suppression of linear crosstalk in optical communication systems using single-carrier implementations. This electrical domain suppression applies spectral shaping in the electronic radio frequency (RF) domain. Advantageously, spectral shaping in the electronic RF domain transfers system complexity from the bulk optical domain into the highly integrated CMOS (or equivalent) domain. The spectral shaping can include electronic circuitry including an electrical filtering block and a signal linearization block prior to optical modulation. The electrical filtering block suppresses coherent interference terms and can include an RF-domain low pass filter. The signal linearization block linearizes modulator response to compensate spectral regrowth due to nonlinear mixing in the modulator.Type: ApplicationFiled: June 24, 2009Publication date: December 30, 2010Inventor: Michael Y. FRANKEL
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Publication number: 20100316392Abstract: An apparatus includes: a first dispersion compensator that is arranged on an optical path between an input port and an output port, that has a dispersion compensation band, and that substantially compensates a chromatic dispersion to signal light by using a variable amount of dispersion compensation, a second dispersion compensator that is arranged on the optical path, that has a dispersion compensation band different from the dispersion compensation band of the first dispersion compensator, and that substantially compensates the chromatic dispersion to the signal light by using a variable amount of dispersion compensation and a controller that controls the first dispersion compensator in accordance with the value of chromatic dispersion to be compensated and that controls the amount of dispersion compensation and the dispersion compensation band in the second dispersion compensator in association with the amount of dispersion compensation in the first dispersion compensator.Type: ApplicationFiled: June 8, 2010Publication date: December 16, 2010Applicant: FUJITSU LIMITEDInventor: Miki ONAKA
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Patent number: 7853151Abstract: In an optical communication system, a pre-compensation is conducted for an influence of a polarization dispersion and a polarization dependent loss, which an optical signal transmitted from a transmitter station to a receiver station receives from a communication channel, at a transmitter station. The influence of the polarization dispersion and the polarization dependent loss from the transmission channel is cancelled when the receiver station receives the optical signal.Type: GrantFiled: July 27, 2005Date of Patent: December 14, 2010Assignee: Fujitsu LimitedInventor: Futoshi Izumi