Including Compensation Patents (Class 398/158)
  • Patent number: 7574138
    Abstract: A device (D2) is dedicated to controlling degradation parameters associated with signals on channels with different wavelengths, possibly arranged in bands of channels, and transmitted by transmission lines (Lj) connecting nodes (Ni) of a transparent optical communication network. The device includes processing means (PM2) adapted, in the event of transmission of signals of at least two channels or bands of channels by at least one transmission line (Lj), to measure for each of said channels or each of said bands of channels, firstly, the value of a parameter representative of the degradation of the signals on the corresponding line (Lj) and, secondly, taking account of said measured values, a power profile to be imposed on the signals so that they have predetermined degradation parameter values.
    Type: Grant
    Filed: January 9, 2004
    Date of Patent: August 11, 2009
    Assignee: Alcatel
    Inventors: Jean-Paul Faure, Vincent Bouder
  • Patent number: 7567759
    Abstract: An optical apparatus comprises a phase comparator detecting a phase shift between a changing point of data transmitted through an electro/opto converter and a changing point of data received through an opto/electro converter, a delay controller and a variable delay circuit controlling a delay of the transmitted data so that the phase shift detected becomes equal to a value which minimizes a receiver sensitivity degradation due to crosstalks between a transmitter portion and a receiver portion.
    Type: Grant
    Filed: October 16, 2006
    Date of Patent: July 28, 2009
    Assignee: Fujitsu Limited
    Inventor: Hiroki Kanesaka
  • Patent number: 7567760
    Abstract: A method and apparatus for providing diagnostic features for an optical transceiver, in which the optical transceiver uses electronic dispersion compensation (EDC) in order to alleviate distortion of a signal caused by dispersion. A method and apparatus for monitoring the performance of an electronic dispersion compensator by monitoring one or more signals from the electronic dispersion compensator and generating an alarm in the vent that the performance of the electronic dispersion compensator falls below a certain threshold.
    Type: Grant
    Filed: June 29, 2006
    Date of Patent: July 28, 2009
    Assignee: Avago Technologies General IP (Singapore) Pte. Ltd.
    Inventors: Andrew Bothwell, Richard Cronin, David Healy
  • Patent number: 7565083
    Abstract: An optical network route and method are disclosed that mitigate distortion in a route having different types of fibers. For an optical network route that includes a plurality of fiber spans of a first type and a fiber span of a second type, assume that the optical network route is transporting optical signals having a plurality of original wavelengths where one or more of the original wavelengths is in a distortion wavelength region of the second type of fiber span. For optical signals entering the second type of fiber span, the original wavelength that is in the distortion wavelength region of the second type of fiber span is shifted to a temporary wavelength outside of the distortion wavelength region. The optical signals then travel over the second type of fiber span. For optical signals exiting the second type of fiber span, the temporary wavelength is shifted back to the original wavelength.
    Type: Grant
    Filed: June 22, 2004
    Date of Patent: July 21, 2009
    Assignee: Sprint Communications Company L.P.
    Inventor: Youichi Akasaka
  • Patent number: 7558479
    Abstract: An optical communications system has a plurality of spans between a transmitter and a receiver. The receiver has optical to electrical conversion circuitry for converting the received optical signal to an electric signal, analogue to digital conversion circuitry and digital signal processing means for analysing the electrical digital signal. The digital signal processing means derives information concerning characteristics of individual spans from the electrical digital signal. This enables parameters such as per-span variations in provisioned power, local dispersion and span loss to be measured. In-service measurements of system characteristics can be used to enable optimisation of the network operation.
    Type: Grant
    Filed: April 15, 2004
    Date of Patent: July 7, 2009
    Assignee: Nortel Networks Limited
    Inventor: Alan Robinson
  • Patent number: 7558478
    Abstract: A method of controlling optical signal traffic in an optical network between a transmitter and a plurality of receivers, where the transmitter is adapted to compensate optical impairments based on at least one optical parameter, includes steps of identifying each path between the transmitter and the plurality of receivers, determining a respective optical parameter for each path, selecting one of the receivers for receiving an optical signal from the transmitter, and enabling the transmitter to generate the optical signal using the respective optical parameter of the path between the transmitter and the selected receiver. By preconfiguring compensation parameters for the various paths in the network, an all-optical network can be implemented wherein optical signals can be switched, added or dropped without having to match dispersion maps or perform optical-electrical-optical regeneration.
    Type: Grant
    Filed: February 28, 2006
    Date of Patent: July 7, 2009
    Assignee: Nortel Networks Limited
    Inventors: James Harley, Kim B. Roberts, Michel Belanger
  • Patent number: 7555220
    Abstract: 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: Grant
    Filed: October 22, 2004
    Date of Patent: June 30, 2009
    Assignee: Infinera Corporation
    Inventors: Stephen G. Grubb, Charles H. Joyner, Frank H. Peters, Fred A. Kish, Jr., Drew D. Perkins
  • Publication number: 20090162074
    Abstract: A wavelength dispersion compensation control method determining whether a clock component is contained in an optical signal received from an optical transmission path and, if a clock component if contained in the optical signal, extracting the clock component, and stopping control of a variable wavelength dispersion compensator when no clock component is extracted.
    Type: Application
    Filed: December 16, 2008
    Publication date: June 25, 2009
    Applicant: Fujitsu Limited
    Inventor: Nobuyuki NEMOTO
  • Publication number: 20090154938
    Abstract: A system generates optical pulses, that include two frequencies within one optical channel, at a first end of an optical link, and receives the optical pulses at a second end of the optical link. The system also sets a frequency difference for the two frequencies of the optical pulses, calculates a relative group delay difference for the two frequencies of the optical pulses, and calculates a residual chromatic dispersion of the channel based on the frequency difference and the calculated relative group delay difference.
    Type: Application
    Filed: December 17, 2007
    Publication date: June 18, 2009
    Applicant: Verizon Services Organization Inc.
    Inventors: Tiejun J. XIA, Glenn A. WELLBROCK
  • Patent number: 7548699
    Abstract: A power supply generates a supply voltage that varies from a first voltage level to a second voltage level. A first current source is coupled to the power supply and generates a current that varies due to channel-length modulation. A channel-length modulation (CLM) compensation mechanism is provided to reduce the current variation of the first current source by compensating the channel-length modulation (CLM) of the first current source.
    Type: Grant
    Filed: December 22, 2005
    Date of Patent: June 16, 2009
    Assignee: Avago Technologies ECBU IP (Singapore) Pte. Ltd.
    Inventors: Kah Weng Lee, Bin Zhang
  • Patent number: 7548696
    Abstract: A fiber-to-the-home (FTTH) system transmits forward and reverse optical signals, such as video, voice, and data signals, via optical fiber, and includes a plurality of home network units. The home network units include an optical receiver for receiving at least one of the video, voice, and data signals. Included is a plurality of gain stages that are distributed throughout the optical receiver. The gain stages include a preamplifier stage, two interstage amplifiers, and a postamplifier stage. Two gain control circuits automatically adjust the gain of the video signal based upon the input power level to the FTTH optical receiver. Additionally, a tilt network performs level compensation for externally located coaxial cable. A signal is then provided to a device located within a home via the coaxial cable at the proper RF level having low noise signals.
    Type: Grant
    Filed: February 15, 2006
    Date of Patent: June 16, 2009
    Assignee: Scientific-Atlanta, Inc.
    Inventor: Robert R. Riggsby
  • Patent number: 7546039
    Abstract: Certain exemplary embodiments comprise a method that can comprise, responsive to an instruction to change a setting of a polarization controller, automatically changing a first rotational speed of a birefringent plate associated with the polarization controller to orient the birefringent plate pseudo-randomly over time with respect to a predetermined axis.
    Type: Grant
    Filed: November 28, 2005
    Date of Patent: June 9, 2009
    Assignee: AT&T Intellectual Property, II, L.P.
    Inventors: Mikhail Boroditsky, Mikhail Brodsky, Nicholas Frigo, Peter Magill
  • Patent number: 7542685
    Abstract: An apparatus and method for transmitting a signal for optical network applications with automatic chromatic dispersion compensation. The apparatus includes a first optical transmitter. The first optical transmitter includes a first light source configured to generate a first laser signal in response to a first laser drive signal, a first data modulator configured to receive the first laser signal and a first data drive signal and output a first chirped return-to-zero signal, and a first signal source configured to generate a first non-return-to-zero signal. Additionally, the apparatus includes a first clock and data recovery system, a first data driver, a first adjustment system, and a first control system.
    Type: Grant
    Filed: May 12, 2004
    Date of Patent: June 2, 2009
    Assignee: FutureWei Technologies, Inc.
    Inventors: Yu Sheng Bai, Rong Zhang
  • Publication number: 20090129781
    Abstract: Optical communication apparatuses capable of performing appropriate communication according to a distance to a receiving apparatus, optical communication methods, and an optical communication system are provided. A transmitting apparatus transmits an optical signal corresponding to data. The transmitting apparatus modulates intensity of the optical signal into intensity corresponding to a distance over which the data is to be delivered and outputs this intensity-modulated optical signal. This allows the transmitting apparatus to change the intensity of the optical signal corresponding to the data according to a distance to a receiving apparatus that receives the data, which thus allows the receiving apparatus to surely receive the data.
    Type: Application
    Filed: September 13, 2006
    Publication date: May 21, 2009
    Applicant: KYOCERA CORPORATION
    Inventors: Yasuyuki Irie, Keijiro Minami, Makoto Chishima
  • Patent number: 7536108
    Abstract: 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: Grant
    Filed: June 26, 2002
    Date of Patent: May 19, 2009
    Assignee: Nippon Telegraph & Telephone Corporation
    Inventors: Akira Hirano, Yutaka Miyamoto, Masahito Tomizawa, Shoichiro Kuwahara, Hiroshi Takahashi, Yasuyuki Inoue
  • Patent number: 7534986
    Abstract: A light emission section, including a light emitting element such as a semiconductor laser, emits a light beam in accordance with communication data. A light reception section, including a light receiving element such as a photodiode, receives the light beam emitted by the light emission section. The light emission section and the light reception section are positioned and an emission angle and an incidence angle of the light beam are determined such that the light beam emitted by the light emission section to the light reception section is prevented from being reflected by a surface of the optical reception section and/or a mounting substrate and being returned to the light emission section.
    Type: Grant
    Filed: April 25, 2007
    Date of Patent: May 19, 2009
    Assignee: Panasonic Corporation
    Inventors: Mariko Nakaso, Hiroyuki Sasai
  • Patent number: 7532400
    Abstract: The invention provides systems and methods enabling high fidelity quantum communication over long communication channels even in the presence of significant loss in the channels. The invention involves laser manipulation of quantum correlated atomic ensembles using linear optic components (110, 120), optical sources of low intensity pulses (10), interferers in the form of beam splitters (150), and single-photon detectors (180, 190) requiring only moderate efficiencies. The invention provides fault-tolerant entanglement generation and connection using a sequence of steps that each provide built-in entanglement purification and that are each resilient to realistic noise levels. The invention relies upon collective rather single particle excitations in atomic ensembles and results in communication efficiency scaling polynomially with the total length of the communication channel.
    Type: Grant
    Filed: October 12, 2007
    Date of Patent: May 12, 2009
    Assignee: MagiQ Technologies, Inc.
    Inventors: Peter Zoller, Luming Duan, Ignacio Cirac, Mikhail D. Lukin
  • Patent number: 7526199
    Abstract: An optical transmission apparatus includes a demultiplexer for separating wavelength-division multiplexing light received from a first optical transmission line into signals of different wavelengths to transmit the signals to an outside and a multiplexer for multiplexing signals of different wavelengths received from the outside to transmit multiplexed signals to a second optical transmission line. An input check unit is provided for monitoring a power level of a signal separated by the demultiplexer and for providing an output indicative thereof. An output adjuster is provided for intercepting a signal from the outside so as to inhibit receipt of the signal from the outside by the multiplexer depending on the output of the input check unit.
    Type: Grant
    Filed: July 20, 2005
    Date of Patent: April 28, 2009
    Assignee: Hitachi Communication Technologies, Ltd.
    Inventors: Kenro Sekine, Junya Kosaka, Tadashi Matsuoka
  • Publication number: 20090103930
    Abstract: An optical interconnect includes an optical transmitter having a plurality of optical sources; a light sensing array configured to receive optical beams emitted from the optical sources; and a beam tracking module in communication with the light sensing array. The beam tracking module is configured to calculate a displacement of at least one of the optical beams by extrapolating an extremum from cross-correlation data obtained between at least a portion of a sample reading from the light sensing array and at least a portion of a plurality of shifted versions of a reference reading from the light sensing array. A related method includes calculating a displacement of an optical beam by extrapolating an extremum from cross-correlation data obtained between a sample reading of the optical beam and at least a portion of a plurality of shifted versions of a reference reading from the light sensing array.
    Type: Application
    Filed: October 17, 2007
    Publication date: April 23, 2009
    Inventors: Raymond G. Beausoleil, William M. Tong, Alexandre M. Bratkovski
  • Patent number: 7522845
    Abstract: A transmitter (11) emits a single wavelength optical signal and transmits this as a wavelength channel (13) in a compound multiplex signal through the WDM network. The receiver (12) selects the single wavelength optical signal (21) from the compound multiplex signal using a band-pass filter. A wavelength fit detector (15) determines a feedback signal by correlating variations of the amplitude of the received signal with variations of the traffic density. This feedback signal is then returned to the transmitter (11) via a back channel (16) and serves to tune the wavelength of the single wavelength optical signal.
    Type: Grant
    Filed: July 14, 2005
    Date of Patent: April 21, 2009
    Assignee: Alcatel
    Inventor: Wolfram Lautenschläger
  • Patent number: 7519299
    Abstract: An optical signal regenerative repeater is provided including at least one first optical 3R repeater based on an optical communication signal pulse, regenerating the optical communication signal pulse. The first optical 3R repeater comprises a first clock extraction unit extracting a clock from the optical communication signal pulse and generating a first optical clock pulse synchronized with the extracted clock. The first optical 3R repeater also comprises a first optical gate, which is opened and closed in accordance with a control light corresponding to the optical communication signal pulse, which receives as a controlled light the first optical clock pulse generated by the first clock extraction unit, and which generates a first regenerated signal pulse corresponding to said optical communication signal pulse. Further, a pulse time width of the control light and the controlled light is different.
    Type: Grant
    Filed: February 9, 2004
    Date of Patent: April 14, 2009
    Assignee: NEC Corporation
    Inventor: Ryosuke Kuribayashi
  • Patent number: 7515833
    Abstract: 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: Grant
    Filed: June 9, 2006
    Date of Patent: April 7, 2009
    Assignee: OpVista Incorporated
    Inventor: Winston I. Way
  • Patent number: 7515831
    Abstract: The present invention is a telecommunication device with an auto-configurable capability that supports both serial and parallel data interfaces. The telecommunication device can transfer configuration data through a serial interface such as I2C interface and a parallel interface such as UPI. The telecommunication device can auto-configure through the I2C interface in master mode. The selectable configuration data stored in a second memory device is fetched by the telecommunication device through the I2C interface.
    Type: Grant
    Filed: February 25, 2005
    Date of Patent: April 7, 2009
    Assignee: O2Micro International Ltd.
    Inventors: Patrick S. Lee, Xiaoguang Yu
  • Publication number: 20090087194
    Abstract: An optical transmission system, where in an optical transmitter a detection bit having a specific pattern set according to the number of bits to be transmitted within one symbol time, is imparted with respect to a transmission signal in which transmission information has been encoded according to a preset format, and an optical signal generated by modulating light according to the transmission signal is transmitted to a transmission line. In an optical receiver, logic inversion or bit swap of received data is detected and compensated by using the detection bit included in the received signal, a decoding process of the compensated received signal is executed. As a result, when an optical signal capable of transmitting multi-bit information within one symbol time is transferred, it is possible to realize excellent transmission characteristics, by reliably compensating an error in received data caused by the modulation format or the multiplex system of the optical signal.
    Type: Application
    Filed: July 29, 2008
    Publication date: April 2, 2009
    Applicant: Fujitsu Limited
    Inventors: Hisao Nakashima, Takeshi Hoshida, Takahito Tanimura, Toru Katagiri, Shoichiro Oda
  • Patent number: 7512344
    Abstract: 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: Grant
    Filed: July 11, 2005
    Date of Patent: March 31, 2009
    Assignee: Hitachi Metals Ltd.
    Inventors: Toshiki Sugawara, Satoshi Makio
  • Patent number: 7512848
    Abstract: A clock and data recovery circuit includes even and odd latches, a detection module, a clock recovery module, a compensating module, and a data recovery module. The even and odd latches are operably coupled to latch even and odd bits of a digital stream of data based on a recovered clock to produce even and odd latched bits. The detection module is operably coupled to produce a phase representative pulse stream based on the even and odd latched bits. The clock recovery module is operably coupled to produce the recovered clock based on the phase representative pulse stream. The compensating module is operably coupled to adjust biasing of the even and odd latches based on operating parameter changes of the clock and data recovery circuit. The data recovery module is operably coupled to produce recovered data from the even and odd latched bits based on the recovered clock.
    Type: Grant
    Filed: September 29, 2004
    Date of Patent: March 31, 2009
    Assignee: Xilinx, Inc.
    Inventor: Firas N. Abughazaleh
  • Publication number: 20090080901
    Abstract: In a dispersion compensating apparatus, a reference identifying unit identifies a reference (X dB down) that makes a penalty lower than a predetermined value in accordance with optical signal information and a reference identifying table, and a VIPA plate temperature adjusting unit adjusts a refractive index of a VIPA plate by modifying a temperature of the VIPA plate so that a transmission center wavelength derived from the reference matches the wavelength defined by an ITU-T Grid. If a dispersion compensation value setting unit performs an optimal residual dispersion value search, the VIPA plate temperature adjusting unit determines if a filtering penalty is lower than a predetermined value in accordance with a penalty management table. If the filtering penalty is lower than the predetermined value, temperature adjustment of the VIPA plate is not performed.
    Type: Application
    Filed: December 1, 2008
    Publication date: March 26, 2009
    Applicant: FUJITSU LIMITED
    Inventors: Akira Miura, Hiroki Ooi, Kiyotoshi Noheji
  • Publication number: 20090074427
    Abstract: Digital compensation of the polarization-mode dispersion (PMD) effects experienced by an optical signal in a transmission link is achieved. A digital representation of the optical fields of two orthogonal polarization components of an optical signal, defined by a polarization beam splitter (PBS), is first obtained. The fiber transmission link is treated as a concatenation of multiple virtual PMD segments, each having two specific principle-state-of-polarization (PSP) axes and causing a differential group-delay (DGD) and a phase delay between two signal components that are polarized along the two PSP axes. The best guesses of the parameters of the PMD segments and the relative orientation between the PSP axes of the last PMD segment and the characteristic polarization axes of the PBS are dynamically obtained. The digital representation of at least one generic component of the field of the optical signal is then computed through matrix operations by using the best guesses.
    Type: Application
    Filed: May 9, 2008
    Publication date: March 19, 2009
    Inventor: Xiang Liu
  • Publication number: 20090073561
    Abstract: In one exemplary embodiment, a method comprises transmitting an optical signal via the optical line, measuring a relative change in spectral intensity of the optical signal near a clock frequency (or half of that frequency) while varying a polarization of the optical signal between a first state of polarization and a second state of polarization, and using the relative change in spectral intensity of the optical signal to determine and correct the DGD of the optical line. Another method comprises splitting an optical signal traveling through the optical line into a first and second portions having a first and second principal states of polarization of the optical line, converting the first and second portions into a first and second electrical signals, delaying the second electrical signal to create a delayed electrical signal that compensates for a DGD of the optical line, and combining the delayed electrical signal with the first electrical signal to produce a fixed output electrical signal.
    Type: Application
    Filed: November 14, 2008
    Publication date: March 19, 2009
    Applicant: Kailight Photonics, Inc.
    Inventors: Er'el Granot, Shalva Ben-Ezra, Gil Blecher, Shai Tzadok, Reuven Zaibel, Roni Dadon, Motti Caspi, Haim Chayet, Yehuda Ganz, Arieh Sher
  • Patent number: 7486893
    Abstract: The disclosed technology provides a dynamic interconnection system which allows to couple a pair of optical beams carrying modulation information. In accordance with the disclosed technology, two optical beams emanate from transceivers at two different locations. Each beam may not see the other beam point of origin (non-line-of-sight link), but both beams can see a third platform that contains the system of the disclosed technology. Each beam incident on the interconnection system is directed into the reverse direction of the other, so that each transceiver will detect the beam which emanated from the other transceiver. The system dynamically compensates for propagation distortions preferably using closed-loop optical devices, while preserving the information encoded on each beam.
    Type: Grant
    Filed: August 15, 2005
    Date of Patent: February 3, 2009
    Assignee: HRL Laboratories, LLC
    Inventors: David M. Pepper, Richard P. Berg
  • Patent number: 7486897
    Abstract: A polarization duobinary optical transmitter is disclosed. The transmitter includes a precoder for coding an electric signal and a light source for generating continuous light. The transmitter also includes a chirped-free modulator for generating an NRZ signal including first and second polarization light beams orthogonal to each other by modulating the light with the electric signal and a band-pass filter for limiting neighbor frequency bands between the first and second polarization light beams.
    Type: Grant
    Filed: March 9, 2006
    Date of Patent: February 3, 2009
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Hoon Kim, Seong-Taek Hwang
  • Patent number: 7486895
    Abstract: The present invention includes apparatus and method of a variable step size dithering control algorithm for polarization mode dispersion controllers (PMDCs). The dithering step size of the PCs is adjusted according to the feedback signal including degree of polarization (DOP).
    Type: Grant
    Filed: December 13, 2005
    Date of Patent: February 3, 2009
    Assignee: Alcatel-Lucent USA Inc.
    Inventors: Dieter Werner, Chongjin Xie
  • Patent number: 7483638
    Abstract: The present invention provides an optical transceiver that enables to reduce the crosstalk from the optical transmitter to the optical receiver. The regenerator of the optical transceiver includes two main amplifiers, a selector, a selector control, and a re-shaper for shaping the receiving signal selected by the selector. The first main amplifier provides a first amplifier and a delay circuit connected in upstream to the first amplifier. The second main amplifier provides a second amplifier and a delay circuit connected in downstream to the second amplifier. The selector selects, based on the phase difference between the receiving signal Rx and the transmitting signal Tx, the output from the first main amplifier or that from the second main amplifier.
    Type: Grant
    Filed: March 7, 2006
    Date of Patent: January 27, 2009
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventor: Shigeo Hayashi
  • Publication number: 20090022499
    Abstract: The present invention provides a system for improving Optical Signal to Noise Ratio “OSNR” (208) of a transmission system using non gain-flattened optical amplifiers (101) and also provide an optically amplified Dense Wavelength Division Multiplexed “DWDM” transmission system that incorporates aforesaid system and has improved channel OSNR (208).
    Type: Application
    Filed: July 16, 2008
    Publication date: January 22, 2009
    Applicant: TEJAS NETWORKS INDIA LTD.
    Inventors: Rajeev ROY, Parthasarathi PALAI, Krishna THYAGARAJAN
  • Publication number: 20090016741
    Abstract: The present invention relates to a method of optical communication, in particular optical communication involving spectral filtering in a passive optical network. The method includes the steps of: (i) performing a first spectral filtering function on a source signal having a spectral width so as to generate a plurality of feeder signals that are spectrally spaced apart from one another; (ii) performing a respective noise reduction function on the feeder signals; (iii) combining the feeder signals over a common waveguide of the optical link; (iv) receiving the feeder signals carried over the optical link and modulating the received feeder signals so as to impose data thereon; and, (v) returning the modulated feeder signals over the optical link so as to communicate the imposed data. Because noise is reduced centrally, a simpler passive optical network can be achieved.
    Type: Application
    Filed: January 11, 2007
    Publication date: January 15, 2009
    Inventors: David W. Smith, Richard Wyatt, Alistair J. Poustie
  • Publication number: 20090016739
    Abstract: A passive optical equalizer and a predistortion technique are employed to reduce pattern effect in optical signals which result from narrow filtering.
    Type: Application
    Filed: July 31, 2007
    Publication date: January 15, 2009
    Applicant: NEC LABORATORIES AMERICA
    Inventors: Jianjun Yu, Lei Xu, Philip Nan Ji, Ting Wang
  • Publication number: 20090016740
    Abstract: A transmitter includes a frequency modulated laser. An optical spectrum reshaper (OSR) is positioned to receive the frequency modulated signal and has a transmission function effective to convert the frequency modulation to amplitude modulation. An optical fiber channel has a first end positioned to receive the filtered signal and a second end proximate a receiver. A filter is positioned between the second end and the receiver and has a peak transmission frequency thereof located on a transmission edge of the OSR, such as at a peak logarithmic derivative value of the transmission function of the optical spectrum reshaper. In some embodiments a first OSR is positioned to receive the frequency modulated signal and configure to output a filtered signal wherein high frequency portions are more attenuated than low frequency portions. A second OSR at the receiver attenuates the low frequency portions substantially more than the high frequency portions.
    Type: Application
    Filed: August 6, 2008
    Publication date: January 15, 2009
    Inventors: Daniel Mahgerefteh, Parviz Tayebati
  • Patent number: 7477848
    Abstract: An optical receiving apparatus sets, efficiently and optimally, a delay interferometer and a variable wavelength dispersion compensator in the apparatus.
    Type: Grant
    Filed: December 13, 2005
    Date of Patent: January 13, 2009
    Assignee: Fujitsu Limited
    Inventors: Hiroki Ooi, Akira Miura, Takeshi Hoshida
  • Publication number: 20090010656
    Abstract: 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: Application
    Filed: February 21, 2008
    Publication date: January 8, 2009
    Applicant: FUJITSU LIMITED
    Inventors: Fumio Futami, Shigeki Watanabe
  • Patent number: 7474860
    Abstract: 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: Grant
    Filed: December 19, 2005
    Date of Patent: January 6, 2009
    Assignee: Alcatel-Lucent USA Inc.
    Inventors: Rene Jean Essiambre, Michael Rubsamen, Peter J. Winzer
  • Publication number: 20090003837
    Abstract: An economic way of determining the chromatic dispersion along a link of a DWDM network is provided. A transmitter modulates the output signals of two lasers operating at two different wavelengths and the modulated output signals are sent into the link. Detectors at each one of a plurality of detection sites along the link determine a phase difference in modulation between the output signals of the two lasers. The chromatic dispersion for each detection site can be calculated from the modulation frequency and determined phase differences at that site.
    Type: Application
    Filed: May 23, 2007
    Publication date: January 1, 2009
    Applicant: CISCO TECHNOLOGY, INC.
    Inventors: Stefano Piciaccia, Fabrizio Forghieri
  • Patent number: 7469102
    Abstract: Various methods, systems, and apparatuses is described in which a passive-opticalnetwork includes a first multiplexer/demultiplexer, a second multiplexer/demultiplexer, a wavelength tracking component, and a transmission wavelength controller. The first multiplexer/demultiplexer is located in a first location. The second multiplexer/demultiplexer is located in a second location remote from the first location. The wavelength tracking component determines the difference between the transmission band of wavelengths of the first multiplexer/demultiplexer and the second multiplexer/demultiplexer to provide a control signal to match the transmission band of wavelengths of the first multiplexer/demultiplexer and the second multiplexer/demultiplexer. The transmission wavelength controller alters an operating parameter of the first multiplexer/demultiplexer based on the control signal to control the transmission band of wavelengths of the first multiplexer/demultiplexer.
    Type: Grant
    Filed: April 18, 2003
    Date of Patent: December 23, 2008
    Assignee: Novera Optics, Inc.
    Inventors: Chang-Hee Lee, Kwang-Uk Chu
  • Publication number: 20080310858
    Abstract: The present invention provides optical compensation for a submarine optical cable optical. A dummy light module generates a dummy light signal according to a continuous spectrum in a predetermined range and a combining module combines a service signal with the dummy light signal. When the dummy light is used for the compensation, conventional problems are solved, including complicated control, difficult realization of the pre-equalization function and inflexible configuration. When service signals are increased, the adjustment for the power of the dummy light signal is avoided; therefore, the control for the dummy light is simplified. In the pre-equalization operation, power control is only performed on the dummy light signal in the single channel or the continuous dummy light signal; therefore, the realization of the pre-equalization function is easy.
    Type: Application
    Filed: March 18, 2008
    Publication date: December 18, 2008
    Applicant: HUAWEI TECHNOLOGIES CO., LTD.
    Inventors: Yiquan LU, Congqi LI, Shanfeng LI
  • Patent number: 7466923
    Abstract: 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: Grant
    Filed: October 3, 2007
    Date of Patent: December 16, 2008
    Assignee: AT&T Corp.
    Inventors: Michael Herbert Eiselt, Jonathan A. Nagel
  • Patent number: 7460792
    Abstract: In an optical communication-use receiving circuit of the present invention, the pulse width of the received pulse which is a binary signal corresponding to the signal optical pulse is specified by using an integration circuit and a trigger generating circuit. If the pulse width of the received pulse is not shorter than a predetermined value, a signal having a fixed pulse width is outputted as an output signal from a one-shot pulse generating circuit, so that a pulse having a constant pulse width corresponding to the specified communication speed is outputted. Accordingly, if the pulse width deriving from the signal optical pulse is larger than a certain value, the communication is deemed as a low-speed communication, and a pulse having a constant pulse width corresponding to the communication speed is outputted. As a result, it is possible to realize a small-size receiving circuit and a small-size electronic device which require no external switching-over terminal.
    Type: Grant
    Filed: July 7, 2005
    Date of Patent: December 2, 2008
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Naruichi Yokogawa, Takeshi Nishino
  • Patent number: 7460788
    Abstract: A transmitting and receiving device, in which the received signal which is produced by the receiving device has only a small amount of crosstalk. This object is achieved by providing a transmitting and receiving device having a transmitting device for producing a transmission signal, a receiving device for producing a received signal, and a compensation device which is connected to the transmitting device and to the receiving device and which at least reduces any crosstalk which is produced by the transmitting device in the receiving device.
    Type: Grant
    Filed: March 8, 2004
    Date of Patent: December 2, 2008
    Assignee: Ezconn Corporation
    Inventors: Karl Schrodinger, Kirk Cook, Yung-Shun Wu
  • Patent number: 7457544
    Abstract: A group delay compensation equalizer is disclosed that employs a single channel four-port WDM device for compensating the group delay experienced by a plurality of wavelengths transmitted over different paths. The transmission differential between two wavelengths is compensated by transmitting the two wavelengths through two different paths where the fiber length in reflecting the second wavelength is equal to the transmission time difference between the two wavelengths. The single channel four-port group delay equalizer effectively provides a unidirectional signal flow, as compared to the conventional equalizer that transmits optical signals bi-directionally. The present invention reduces the cost of a group delay equalizer by simplifying the use of multiple three-port WDM devices into a single channel four-port WDM device.
    Type: Grant
    Filed: November 16, 2004
    Date of Patent: November 25, 2008
    Assignee: Avanex Corporation
    Inventors: John Feng, Xuehua Wu, Sanjai Parthasarathi, Giovanni Bararossa
  • Patent number: 7457547
    Abstract: In an optical system including an optical input port for projecting an input optical signal onto an optical phased matrix array, an optical phased matrix array including a plurality of individually addressable pixels thereon, each said pixel being drivable within a prescribed range of levels, and an optical output port for collecting a predetermined fraction of said optical signal received from said optical phased matrix array; a method of compensating for phase distortions including the steps of: (a) determining a plurality of transfer functions relating said level of each said pixel to the phase variation each said pixel introduces to light from said input optical signal which is incident thereon; and (b) controlling the level of selected ones of said pixels in accordance with a corresponding transfer function such that said fractional signal received at said output port is modified in phase to substantially compensate for optical phase distortions arising from said optical phased matrix array.
    Type: Grant
    Filed: November 8, 2004
    Date of Patent: November 25, 2008
    Assignee: Optium Australia Pty Limited
    Inventors: Steven J. Frisken, Glenn W. Baxter, Hao Zhou, Dmitri Abakoumov
  • Patent number: 7457546
    Abstract: An optical transmission system that alleviates waveform distortions due to nonlinear effects in fibers. A transmitter sends WDM signals to a receiver over a dispersion-managed optical transmission line with in-line optical repeaters. The transmission line is divided into a plurality of dispersion compensation intervals each composed of a main segment and a compensation segment. Chromatic dispersion is managed such that the dispersion compensation intervals have a non-zero net dispersion at every boundary point between them, or such that the number of zero-dispersion boundary points is reduced. The main segment is a series of repeater sections with negative dispersion, while the compensation segment is a single repeater section with positive dispersion.
    Type: Grant
    Filed: December 30, 2003
    Date of Patent: November 25, 2008
    Assignee: Fujitsu Limited
    Inventors: Toshiki Tanaka, Takao Naito
  • Publication number: 20080279565
    Abstract: The present invention discloses an apparatus and method for adaptive dispersion compensation, the apparatus comprising: a coarse-grain tunable dispersion compensator, a receiver with electric adaptive dispersion compensator, and a control logic unit. In the method, firstly it is to perform optical dispersion compensation for the input optical signals; then to perform electric dispersion compensation for the optical signals for which the optical dispersion compensation is performed; it is to detect the performance parameters of the receiving of the optical signals for which the electric dispersion compensation has been performed, and based on the performance parameters, it is to perform optical dispersion compensation adjustment for said input optical signals. With an optical de-multiplexer further, said apparatus can perform adaptive dispersion compensation for the multi-channel system.
    Type: Application
    Filed: December 20, 2005
    Publication date: November 13, 2008
    Applicant: ZTE CORPORATION
    Inventor: Huade Shu