Monitoring Patents (Class 398/177)
  • Patent number: 7010234
    Abstract: An all-optical 3R regenerator (AO3R) and a method for using the AO3R to retime, reshape and retransmit an optical signal are described herein. The AO3R includes a polarizer that receives an input optical signal which is of unknown, potentially varying phase and outputs a stable polarized input optical signal. The AO3R also includes a first interferometer (e.g., interferometric converter module) that retimes and reshapes the polarized input optical signal and transmits the retimed and reshaped polarized input optical signal as a polarized output optical signal. The first interferometer is able to retime the polarized input optical signal with the aid of a laser and a clock recovery mechanism.
    Type: Grant
    Filed: July 29, 2002
    Date of Patent: March 7, 2006
    Assignee: Alcatel Optronics USA, Inc.
    Inventor: Brian A. Chaput
  • Patent number: 6980745
    Abstract: An optical transmission system ensuring high-quality monitor control even if an optical fiber fault occurs. A monitor instruction sending unit sends a monitor instruction. An operating condition recognizing unit receives a response signal and recognizes the operating condition. A filtering unit filters the monitor instruction and the response signal. A monitor control unit monitors the operating condition of its own repeater in response to the monitor instruction, and generates resultant response information. A pump unit generates a pump light to cause Raman amplification within an optical fiber transmission medium. A regeneration control unit performs a regeneration control of the response signal to thereby create a regenerated signal. A modulation control unit modulates the pump light by the response information or the regenerated signal to thereby generate the response signal.
    Type: Grant
    Filed: December 14, 2001
    Date of Patent: December 27, 2005
    Assignee: Fujitsu Limited
    Inventors: Hiroyuki Deguchi, Shin-ichirou Harasawa, Izumi Yokota
  • Patent number: 6980740
    Abstract: A unique sensor is used to detect a transmission impairment that may have affected incoming optical channel signals. The sensor, more specifically, selects a group of the incoming channel signals and generates a first power signal, P0, over the selected group of signals and generates a second power signals, P1, over a weighted version of the selected group of channel signals. The sensor then generates, as a function of the first and second power signals, P0 and P1, a signal indicative of whether the particular transmission impairment affected the levels of individual ones of the incoming channel signals. If so, then control apparatus offsets the impairment accordingly.
    Type: Grant
    Filed: June 22, 2000
    Date of Patent: December 27, 2005
    Assignee: Lucent Technologies Inc.
    Inventors: Nathan M. Denkin, Wenhua Lin, Fatimah Shehadeh
  • Patent number: 6937820
    Abstract: The present invention relates to an optical level control method for use in an optical transmission system. In the system, a WDM terminal comprises a multiplexing/demultiplexing unit, an amplifier, an up-direction OSC light transmitting/receiving unit, an up-direction multiplexer, an up-direction branching unit, an amplifier and an APR control unit, and a repeater comprises an up-direction branching unit, an OSC light transmitting/receiving unit, an amplifier, an up-direction multiplexer, a down-direction branching unit, an amplifier, a down-direction multiplexer and an APR control unit. In this configuration, a flexible optical output level control in connection with variation in WDM light level, a selective value irrespective of occurrence of an error stemming from the passage of time and avoidable malfunctions are respectively capable. In addition, a trouble retrieving operator can eliminate the possibility of being exposed to the WDM light.
    Type: Grant
    Filed: February 26, 2001
    Date of Patent: August 30, 2005
    Assignee: Fujitsu Limited
    Inventors: Hiroyuki Iwaki, Tetsuo Wada
  • Patent number: 6922532
    Abstract: A performance monitoring method for an optically amplified transmission system. The method provides the optical power at each amplifier site, taking into account the inaccuracies introduced by the SRS in the power estimation obtained with the current methods. An optical spectrum analyzer is used at the output of the transmission link of interest to accurately measure the output power of each wavelength. This value is sent upstream to the last amplifier in the link, to compute an error term as the difference between the actual measurement and the estimation. The error term is used to infer the SRS-induced error by system elements not accounted for in the model. The error term is then fed-back to each amplifier in the link, so that the estimated power is adjusted to account for the SRS-induced inaccuracy.
    Type: Grant
    Filed: December 7, 2000
    Date of Patent: July 26, 2005
    Inventors: Frederic Simard, David W. Park
  • Patent number: 6909853
    Abstract: An apparatus for transferring monitor signals, which apparatus receives a primary signal, and a secondary signal for monitoring a wavelength, and outputs the primary signal and the modulated secondary signal. The apparatus includes an optical coupler to which the primary signal is input, a first optical branching filter optically connected to a signal output terminal, a first optical amplifier optically connected in series between the optical coupler and the first optical branching filter, and a first optical band-pass filter optically connected in series between the optical coupler and the first optical branching filter, but optically connected in parallel with the first optical amplifier. The primary signal is input into the optical coupler and output from the signal output terminal through the first optical amplifier and the first optical branching filter.
    Type: Grant
    Filed: May 8, 2000
    Date of Patent: June 21, 2005
    Assignee: NEC Corporation
    Inventor: Makoto Yamashita
  • Patent number: 6907196
    Abstract: An arrangement and a method for testing a telecommunications circuit over Dense Wavelength Division Multiplexing (DWDM). A transmitter, which is optically coupled to the circuit, transmits a test-drive signal on the circuit. Through a network, a performance of the circuit is monitored at points along the circuit based on the transmitted test-drive signal.
    Type: Grant
    Filed: June 23, 2004
    Date of Patent: June 14, 2005
    Assignee: Sprint Communications Company L.P.
    Inventors: Douglas L. Richards, David W. Williams, Francis R. Yarkosky
  • Patent number: 6847743
    Abstract: A polarization scrambler unit includes a plurality of polarization scramblers, a switching unit for coupling one of the polarization scramblers to a transmission line fiber, a detection unit for detecting an output signal from the polarization scrambler coupled to the transmission line fiber, and a controlling unit for switching, via the switching unit, between the polarization scramblers and another polarization scrambler whenever a false output signal is detected by the detection unit. Thus, the polarization scrambler unit has a redundant structure.
    Type: Grant
    Filed: August 21, 2002
    Date of Patent: January 25, 2005
    Assignee: NEC Corporation
    Inventor: Shohei Yamaguchi
  • Patent number: 6839523
    Abstract: In a method and system for evaluating distributed gain in an optical transmission system, a data signal and a residual pump laser signal propagating in opposite directions within a waveguide are monitored. Modulation of the residual pump laser signal is correlated with low frequency components of the data signal. This correlation is used to determine cross-talk between the data signal pump laser signals, as a function of location within the waveguide. The distributed gain is then evaluated from the cross-talk, using a known relationship, or proportionality, between gain and cross-talk.
    Type: Grant
    Filed: May 11, 2001
    Date of Patent: January 4, 2005
    Assignee: Nortel Networks Limited
    Inventor: Kim B. Roberts
  • Patent number: 6839522
    Abstract: Optical systems, device, and methods including signal varying devices, such as optical amplifiers, attenuators, and filters that have controllable gain, loss and transparent intensity profiles, and which can include and be responsive to one or more local and remote controllers.
    Type: Grant
    Filed: March 26, 2001
    Date of Patent: January 4, 2005
    Assignee: Corvis Corporation
    Inventors: Stephen G. Grubb, Raymond Zanoni, Thomas D. Stephens
  • Publication number: 20040252999
    Abstract: The present invention aims at providing a method for controlling wavelength characteristics of optical transmission powers by Raman amplification, in which the wavelength characteristics of optical transmission powers are automatically compensated without giving any losses to channel lights to thereby improve transmission characteristics, and an apparatus adopting the same. To this end, the method for controlling wavelength characteristics of optical transmission powers by Raman amplification according to present invention supplies Raman pump light to an optical transmission path (Raman amplifying medium); compensates the wavelength characteristics of optical transmission powers caused by transmission of WDM signal light through the optical transmission path, by gain wavelength characteristics of generated Raman amplification; and monitors the wavelength characteristics of optical transmission powers after Raman amplification to thereby control the gain wavelength characteristics of Raman amplification.
    Type: Application
    Filed: July 16, 2004
    Publication date: December 16, 2004
    Applicant: Fujitsu Limited
    Inventors: Miki Onaka, Susumu Kinoshita
  • Patent number: 6832052
    Abstract: An optical transponder capable of effecting performance monitoring on the electrical signal equivalents of at least two different optical signal types each uniquely identifiable in terms of transmission protocol and/or bit rate. The optical transponder includes an optical/electrical (O/E) receiver module for converting an ingressing optical signal from an optical signal source into an electrical signal; a performance monitoring module for effecting performance monitoring on the electrical signal; and an electrical/optical (E/O) transmitter module for regenerating an egressing optical signal from the electrical signal for feeding to an optical signal destination.
    Type: Grant
    Filed: May 17, 2000
    Date of Patent: December 14, 2004
    Assignee: ECI Telecom Ltd.
    Inventor: Oren Marmur
  • Patent number: 6819875
    Abstract: The present invention provides an optical wavelength multiplexing transmission apparatus and an optical output control method for an optical wavelength multiplexing transmission apparatus in an optical wavelength multiplexing transmission system using a main signal light and an OSC light. The optical wavelength multiplexing transmission apparatus (10a) is made up of a first transmitting/receiving section (52a), a second transmitting/receiving section (52b) and an apparatus supervisory control unit (54). This can not only achieve quick restoration from troubles, but also stably calculate an optical output level even if a change of the number of wavelengths to be multiplexed takes place in a main signal light, and even save troublesome adjustments for the improvement of reliability of a transmission line while eliminating the need for a signal source for the adjustment of a receive optical level at the initial installation.
    Type: Grant
    Filed: October 3, 2002
    Date of Patent: November 16, 2004
    Assignee: Fujitsu Limited
    Inventor: Eisaku Touma
  • Patent number: 6816683
    Abstract: A supervisory system in a wavelength division multiplexing communications network is provided with a first and a second terminal stations and a repeater unit. The first terminal station transmits a supervisory signal to the second terminal station. The second terminal station transfers the supervisory signal to the repeater unit to be monitored. Paths to a hub station A and a hub station B can be a single path by looping back a supervisory signal output from the hub stations A and B for issuing and terminating the supervisory signal at a first and a second branch stations connected through an optical wavelength multiplexing/demultiplexing unit. If the hub station B loops back a supervisory signal, the supervisory signal output from the hub station A can be returned to the hub station A again after circulating the path.
    Type: Grant
    Filed: August 9, 2002
    Date of Patent: November 9, 2004
    Assignee: Fujitsu Limited
    Inventors: Takafumi Terahara, Takeo Osaka, Shin-ichirou Harasawa
  • Publication number: 20040218928
    Abstract: An optical network comprises a central source providing light in a plurality of spaced wavelength bands and including variable-gain optical amplifiers enabling the relative intensity of light in respective wavelength bands to be varied. A wavelength-routed network (preferably but not necessarily passive) receives light in all the wavelength bands from the central source and routes each wavelength band to a respective terminals. The terminals are operable to modulate and return received light in any of the said wavelength bands, and may be simple and identical, requiring no precision light source, as would otherwise be needed to allow multiplexing to use optical fibre efficiently. The operator can adjust the semiconductor optical amplifiers to illuminate or disable individual terminals, as required, and can alter the intensity (and if required type) of light supplied to the terminals to maintain a satisfactory signal level, minimising need for engineer visits.
    Type: Application
    Filed: January 29, 2004
    Publication date: November 4, 2004
    Inventors: David Cotter, Peter Healey, David William Smith, Paul David Townsend
  • Patent number: 6810214
    Abstract: In one aspect of the invention, a system operable to reduce degradation of an optical signal to noise ratio where signals having multiple wavelengths are communicated over a common optical link includes an amplifier assembly operable to introduce to a lower communication band a first gain and to introduce to a higher communication band a second gain that is different from the first gain. In addition, the system is operable to introduce a variable gain tilt into at least one of the communication bands. The different gains introduced to the higher and lower bands and the variable gain tilt introduced into at least one of the bands result in a reduction of a degradation of optical signal to noise ratio that could otherwise be caused by wavelength dependent attenuation when the communication bands are combined and communicated over an optical link.
    Type: Grant
    Filed: March 16, 2001
    Date of Patent: October 26, 2004
    Assignee: Xtera Communications, Inc.
    Inventors: Michel W. Chbat, Herve A. Fevrier, Pavle Gavrilovic, Hyunchin Kim, Andrej B. Puc
  • Patent number: 6810210
    Abstract: A communication path impairment detection module for connection to a duplex optic communication link is provided. The duplex optic communication link includes an outgoing communication path and an incoming communication path, each being characterized by a data channel and an optical service channel. The communication path impairment detection module includes a first port and a second port suitable for coupling to the outgoing and incoming communication paths respectively. The communication path impairment detection module is responsive to impairment of the data channel and of the optical service channel in the incoming communication path to impair the data channel and the optical service channel in the outgoing communication path.
    Type: Grant
    Filed: July 31, 2000
    Date of Patent: October 26, 2004
    Assignee: Nortel Networks Limited
    Inventor: Marc Veilleux
  • Patent number: 6807370
    Abstract: An optical transmission system with a mechanism to locate a fault on a transmission line effectively and efficiently to ensure the quality of communication between end stations and repeaters. Repeaters respond to a monitoring control command sent from an end station, returning a monitoring report signal that indicates their current operating status and input/output signal conditions. In the end station, a monitoring report processor identifies a faulty link section of the optical transmission line, if the monitoring report signal indicates a fiber fault. The end station sends a troubleshooting control command to cause a relevant repeater to transmit a probing light pulse signal and a complementary light pulse signal simultaneously in opposite directions. Some of the probing light pulse is reflected back as a result of Rayleigh scattering. The end station locates the fiber fault by analyzing the backscatter, using the complementary light pulse signal for synchronization.
    Type: Grant
    Filed: August 15, 2001
    Date of Patent: October 19, 2004
    Assignee: Fujitsu Limited
    Inventor: Shin-ichirou Harasawa
  • Patent number: 6804464
    Abstract: A method and devices for individually controlling the signal strength of single or multiple optical channels. A controller module monitors the signal strength of channels and amplifies those that need amplifying while attenuating those that are too strong using the same Erbium doped fiber amplifier. A controllable compensation module receives at least one channel and, when required, can either amplify or attenuate the signal strength of the channel(s). The module can be constructed out of a single fiber with an associated pump laser. If the laser provides insufficient pumping power, the fiber acts as an attenuator. If the laser provides a higher level of pump power, the fiber acts as an amplifier.
    Type: Grant
    Filed: February 13, 2001
    Date of Patent: October 12, 2004
    Assignee: Dowslake Microsystems Corporation
    Inventor: Dan Dan Yang
  • Patent number: 6804469
    Abstract: A supervisory system and supervisory method of an optical amplifier repeater are proposed that can implement operation supervision taking account of the characteristics of individual supervisory targets of the optical amplifier repeater, thereby achieving higher reliability.
    Type: Grant
    Filed: June 27, 2001
    Date of Patent: October 12, 2004
    Assignees: Mitsubishi Denki Kabushiki Kaisha, KDDI Corporation, KDD Submarine Cable Systems Inc.
    Inventors: Yasunori Kasahara, Hideki Goto, Takashi Mizuochi, Kenkichi Shimomura, Yukio Horiuchi, Masatoshi Suzuki, Daishi Ishii, Toshio Kawazawa
  • Patent number: 6801720
    Abstract: The present invention has an object to obtain an optical signal quality supervisory device that supervises the quality of an optical signal simply, efficiently and with high accuracy without inviting an increase in cost, an increase in circuit scale and increase in power consumption. The bit rate of the optical supervisory channel is made lower than the bit rate of the optical main channel that is transmitted over an optical communication system, but the reception electric band width of a receiver that receives the optical supervisory channel is made equal to or wider than the reception electric band width of a receiver that receives the optical main channel. Also, the optical supervisory channel is made up of an SOH (section over head) frame to detect an error of the BIP (bit interleaved parity) byte of SOH, thereby supervising the quality of the optical communication system, in particular, the light wave network.
    Type: Grant
    Filed: April 28, 2000
    Date of Patent: October 5, 2004
    Assignees: Mitsubishi Denki Kabushiki Kaisha, KDD Corporation
    Inventors: Takashi Mizuochi, Yojiro Osaki, Aritomo Uemura, Hiroshi Ichibangase, Kiwami Matsushita, Tadayoshi Kitayama, Shu Yamamoto, Tetsuya Miyazaki, Takatomi Kabashima, Naoki Kobayashi
  • Publication number: 20040184817
    Abstract: An optical transmission system with optical amplifier repeaters whereby a flattened gain spectrum can be obtained even when a small number of pumping light sources is used in a Raman amplifier repeater. In the optical transmission system with optical amplifier repeaters, first optical amplifier repeaters at plural stages and a second optical amplifier repeater having a gain control function are located in a gain control zone. The respective first optical amplifier repeaters perform backward pumping to corresponding Raman amplification optical fibers by outputting pumping lights having different wavelengths by backward pumping. Accordingly, a variety of wavelengths are used in the gain control zone as a whole. Consequently, it becomes possible to obtain a flattened gain spectrum. Further, the second optical amplifier repeater performs a control of compensating distortion of spectral characteristics when a failure occurs in at least one of the first optical amplifier repeaters.
    Type: Application
    Filed: February 9, 2004
    Publication date: September 23, 2004
    Applicant: NEC CORPORATION
    Inventors: Jyunko Iwasaki, Ryu Yokoyama
  • Patent number: 6785242
    Abstract: A monitoring apparatus and method are provided for a communication system in which a central office communicates to at least one end unit using intermediate remote nodes. The remote node receives signals from both the central office and the end units. Each remote node can be equipped with apparatus for monitoring the integrity of paths of the communication system. The monitoring apparatus can include a mixing device that mixes received signals to produce combined signals. The received signals generally include a pilot signal sent from the central office and a data signal sent from the at least one end unit. The state of the communication system is analyzed based on the combined signals. If the combined signals includes only the data signal from the end unit, the path through which the pilot signal was sent is inoperative. If the combined signals includes only the pilot signal, the transmission path from the end unit over which the data signal is sent is inoperative.
    Type: Grant
    Filed: July 17, 2001
    Date of Patent: August 31, 2004
    Assignee: AT&T Corp.
    Inventors: Thomas Edward Darcie, Alan H. Gnauck, Xiaolin Lu
  • Publication number: 20040161244
    Abstract: An optical amplifying and relaying system capable of easily and highly accurately monitor troubles in optical amplifiers provided in an up and a down optical fiber transmission line opposing each other is disclosed. Monitoring light signal folding-back lines including variable optical attenuators 4a and 4b and wavelength selective reflecting means 5a and 5b, respectively, are provided between optical transmission lines L1 and L2, which oppose each other and on which optical amplifiers 4a and 4b are disposed each other.
    Type: Application
    Filed: February 18, 2004
    Publication date: August 19, 2004
    Applicant: NEC Corporation
    Inventors: Ryu Yokoyama, Takaaki Ogata
  • Patent number: 6778730
    Abstract: Disclosed herein is an optical signal processing device which can give stable temporal order to the modulation-phases of a plurality of optical signals. The optical signal processing device includes an optical demultiplexer and an optical multiplexer for adaptation to WDM (wavelength division multiplexing). The optical demultiplexer has an input port and a plurality of output ports. The input port is adapted to accept WDM signal light obtained by wavelength division multiplexing a plurality of optical signals having different wavelengths. The optical multiplexer has an output port and a plurality of input ports. The plural output ports of the optical demultiplexer and the plural input ports of the optical multiplexer are connected by a plurality of optical paths, respectively. Each optical path is provided with a delay adjuster.
    Type: Grant
    Filed: March 13, 2001
    Date of Patent: August 17, 2004
    Assignee: Fujitsu Limited
    Inventor: Kazuo Hironishi
  • Publication number: 20040146306
    Abstract: A technique for maintaining a required value of power per optical communication channel in a chain of optical nodes (112, 114, 118, 116) connected by optical fiber spans (111, 119, 121), wherein at least some of the nodes include optical amplifiers (112, 114, 116) with controllable gains, the technique comprises performing automatic gain control at the optical amplifiers so that, in the frame of power gain of each particular optical amplifier (114, 116), to compensate a preceding span loss. The span loss is calculated as power loss on an optical fiber span (111, 121) incoming the particular amplifier.
    Type: Application
    Filed: January 14, 2004
    Publication date: July 29, 2004
    Applicant: ECI TELECOM LTD.
    Inventors: Tal Muzicant, David Harris
  • Publication number: 20040136728
    Abstract: In an optical transmission system which can keep a flat pass characteristic within an optical signal modulation band, a spectrum of a dropped optical signal within a modulation band per channel is monitored, and non-flatness for the optical signal is compensated by detecting the non-flatness of a pass characteristic of a transmission line from the spectrum.
    Type: Application
    Filed: December 9, 2003
    Publication date: July 15, 2004
    Inventors: Motoyoshi Sekiya, Ryosuke Goto
  • Patent number: 6751421
    Abstract: The present invention uses wavelength conversion to increase the bandwidth of optical communication systems. In an exemplary embodiment, a combination of wavelength conversion and amplification with a discrete optical amplifier (OA) to allow communications systems to operate in wavelength bands &lgr;′ outside the gain bandwidth of the OA. A transmitter launches signal channels (&lgr;1′, &lgr;2′, . . . , &lgr;′N) that are outside the gain bandwidth &lgr;. A wavelength conversion device upstream of the amplifier maps channels &lgr;′1, &lgr;′2, . . . &lgr;′N to corresponding wavelengths &lgr;1, &lgr;2, . . . &lgr;N within &lgr;. The OA directly amplifies the converted signals and a second wavelength conversion device downstream of the amplifier maps the amplified signals back to the original channels &lgr;′1, &lgr;′2, . . . &lgr;′N.
    Type: Grant
    Filed: October 4, 1999
    Date of Patent: June 15, 2004
    Assignee: Lucent Technologies Inc.
    Inventors: Jinendra Kumar Ranka, Andrew John Stentz
  • Publication number: 20040109694
    Abstract: Gain setting of a receiving amplifier is performed by use of ASE light of a transmitting amplifier, without need of a particular light source for the receiving amplifier gain setting.
    Type: Application
    Filed: December 3, 2003
    Publication date: June 10, 2004
    Applicant: FUJITSU LIMITED
    Inventors: Manabu Suzuki, Miwa Taniguchi, Toshihiro Suzuki, Shingo Hara
  • Patent number: 6748179
    Abstract: The system and method of the present invention is operative to monitor the performance of an optical communications channel. An optical splitter splits a wavelength division multiplexed (WDM) optical communications signal into a low power WDM signal onto a back-up path, where a tunable filter sweeps the optical communications channels, while a monitoring circuit monitors the optical communications channels for performance. Optical power can be stored and subsequently displayed, providing an optical spectrum analysis of the signal.
    Type: Grant
    Filed: March 7, 2001
    Date of Patent: June 8, 2004
    Assignee: Harris Corporation
    Inventors: Michael Lange, Edward Tegge, John DeSalvo
  • Patent number: 6741814
    Abstract: A balun is constructed from a parallel pair of lines (coaxial or bifiler) that are bent to form a U-shape including a more curved (bent) section with two ends each of which are connected to a respective less curved (straight leg) section. One or more single hole ferrite beads are threaded over each respective pair of less curved sections of the pair of lines.
    Type: Grant
    Filed: April 1, 1999
    Date of Patent: May 25, 2004
    Assignee: Koninklijke Philips Electronics N.V.
    Inventor: Joel Kosoff
  • Publication number: 20040086279
    Abstract: Disclosed is a wavelength-division multiplexing optical transmission system in which an optical lossy medium, optical amplifiers and Raman amplifiers for compensating for loss in the optical lossy medium are cascade-connected. The system includes power-level equalizing means for equalizing optical power levels input to an optical amplifier of a succeeding stage by adjusting excitation ratio of a Raman amplifier; optical-SNR equalizing means for adjusting power levels at a transmitting end to equalize optical SNRs at a receiving end; and correction-value acquisition means for acquiring a correction value that represents an amount of change in power of each wavelength before and after optical-SNR equalization control.
    Type: Application
    Filed: October 22, 2003
    Publication date: May 6, 2004
    Applicant: Fujitsu Limited
    Inventors: Takeshi Sakamoto, Tetsuo Wada, Yoshinori Tochiki
  • Patent number: 6731872
    Abstract: A central equipment is connected by at least two optical fibers to a decentralized optical equipment and the central equipment creates an optical auxiliary signal which is transmitted together with an optical payload signal from the central equipment to the decentralized equipment. The optical auxiliary signal that is received in the decentralized optical equipment is rerouted and transmitted back to the central optical equipment via another optical fiber in addition to a second payload signal, and the reception of the optical auxiliary signal is optically monitored in the central optical equipment to determine if there is a breakage in either one of the fibers extending to the unit.
    Type: Grant
    Filed: March 1, 2000
    Date of Patent: May 4, 2004
    Assignee: Siemens Aktiengesellschaft
    Inventors: Hubert Jaeger, Gerhard Stortz, Detlef Stoll, Reinhard Johannsen, Wilhelm-Martin Plotz
  • Patent number: 6728212
    Abstract: The invention is an apparatus and method for scheduling the flow of packets. Its purpose is to reduce excess loads, while at the same time, improving efficiency of the system. The scheduler is divided into two or more schedulers operating in parallel. Furthermore, each scheduler is assigned a subset of the available wavelengths. The assignment of wavelengths is done in an asymmetric manner such that one scheduler is assigned many more wavelengths. In addition, the void filling scheduler is used in conjunction with bandwidth grabbing to improve scheduling performance. In a preferred embodiment, the buffer occupancy of a first scheduler is monitored. If it is below a threshold (and a second scheduler's buffer is full), then packets intended for the second scheduler are transferred to the first scheduler.
    Type: Grant
    Filed: June 23, 2000
    Date of Patent: April 27, 2004
    Assignee: Alcatel
    Inventor: Ljubisa Tancevski
  • Publication number: 20040057732
    Abstract: A photo amplifying apparatus for amplifying wavelength division multiplexed signals includes a specific wavelength measuring unit for measuring a specific wavelength at a measuring point, a total power measuring unit for measuring all wavelengths at the measuring point, and an output control unit for controlling the output of the photo amplifying apparatus based on the light power measured by the specific wavelength measuring unit and the total power measuring unit. Since the photo amplifying apparatus measures both the specific wavelength and all wavelengths, the photo amplifying apparatus can determine change in the number of multiplexed wavelengths and the gain gradient of the photo signals, and can properly control its output level.
    Type: Application
    Filed: August 13, 2003
    Publication date: March 25, 2004
    Applicant: FUJITSU LIMITED
    Inventors: Kaoru Usui, Yoshio Shimano, Hiroshi Iizuka, Hiroyuki Itou
  • Publication number: 20040052534
    Abstract: An optical regenerator enabling matching of self-phase modulation induced spectral broadening and optical regenerator filter center wavelengths and bandwidths for different fiber dispersion values. The regenerator monitors the central part of an input signal spectrum at the output of a non-linear medium and suppresses the power at the center wavelength to allow for a constant spectral broadening for different fiber dispersion values. The regenerator utilizes a control filter to control a variable amplifier via a feedback loop, and the variable amplifier adjusts the power of the signal launched into the non-linear medium to ensure a sufficient self-phase modulation broadened spectrum.
    Type: Application
    Filed: September 16, 2002
    Publication date: March 18, 2004
    Applicant: Fitel U.S.A. Corp.
    Inventor: Carsten Gudmann Joergensen
  • Patent number: 6708004
    Abstract: An optical communication system is provided that includes first and second optical transmitters/receivers remotely located with respect to one another and which are coupled together by first and second optical transmission paths for bidirectionally transmitting optical information therebetween. First and second optical amplifiers are respectively disposed in the first and second optical transmission paths. At least one loop-back path optically couples a portion of a WDM optical signal from the first to the second transmission path. The loop-back path includes a filter for transmitting a monitoring channel but not a data channel included in the optical signal portion traversing the loop-back path.
    Type: Grant
    Filed: December 1, 1998
    Date of Patent: March 16, 2004
    Assignee: Tyco Telecommunications (US) Inc.
    Inventor: Glen Mitchell Homsey
  • Publication number: 20040037568
    Abstract: An optical transmission system includes a first transmitter unit and a first receiver unit. A first optical transmission path interconnects the first transmitter unit and the first receiver unit. The first optical transmission path is defined by at least three transmission spans. The first optical transmission path has a periodic dispersion map with a first periodic component comprising a fixed portion and an adjustable portion, and a second periodic component greater in length than the first periodic component. The fixed portion of the first periodic component of the periodic dispersion map is provided by the respective transmission spans. A plurality of optical repeaters each optically couple adjacent ones of the transmission spans to one another. A first plurality of adjustable dispersion trimming element are each located in one of the optical repeaters and optically couples one of the transmission spans to an optical amplifier located in the optical repeater.
    Type: Application
    Filed: July 3, 2003
    Publication date: February 26, 2004
    Inventor: Stephen G. Evangelides
  • Patent number: 6697577
    Abstract: A tuning system for use in a receiver of an optical transmission system. The receiver includes a data channel transporting a data signal and a monitoring channel transporting a copy of the data signal. The tuning system includes a processing module for processing the copy of the data signal to generate a control signal conveying tuning information. This tuning information is used by the receiver to alter an operating point of the receiver on the data channel. The operating point of the receiver that is susceptible to be altered by the control signal is a decision threshold applied on the data signal to discriminate one binary value from another binary value on the data channel of the receiver. This approach allows, when required or desired, tuning of the system while the system is in service. This is possible since the tuning of the system is performed using the monitoring channel, and does not disturb nor corrupt the actual data being transported on the data channel.
    Type: Grant
    Filed: November 1, 1999
    Date of Patent: February 24, 2004
    Assignee: Nortel Networks Limited
    Inventors: Jinghui Li, Hugues Tournier, Joel Milgram, Suet Yuen, LeRoy Pick, Stephen Roberts, Bernard Thiboutot
  • Patent number: 6697190
    Abstract: Methods and devices for controlling an optical device. In one embodiment, the optical device is directly controlled by an outside analog electrical signal. Depending on the voltage or current level of the electrical signal, the output of the optical device is changed accordingly. An operational amplifier may be used to amplify the analog electrical signal prior to the signal being received by the circuitry of the optical device. For maximum flexibility in control, a switch can be coupled to the operational amplifier so that either analog or digital control signals can be used.
    Type: Grant
    Filed: May 16, 2002
    Date of Patent: February 24, 2004
    Assignee: Dowslake Microsystems Corporation
    Inventor: Dan Dan Yang
  • Patent number: 6687044
    Abstract: Control information is embedded in the signal passing through an optical amplifier by varying the power level of that amplifier's pumped laser source. Connection discovery for a given optical port can then be performed by detecting variations in the optical signal present on that given port and then attempting to match these with the variations assigned to each of the optical amplifiers. If a match is found, then the optical amplifier connected to the given port can be identified. As a result, the need to physically handle the fiber in order to effect connection discovery is eliminated, rendering the process faster, safer and more reliable. Also, the present invention advantageously allows a connection discovery function to be invoked from a remote location.
    Type: Grant
    Filed: December 20, 2001
    Date of Patent: February 3, 2004
    Assignee: Nortel Networks Limited
    Inventors: Mario Paquet, Marc Veilleux
  • Publication number: 20040013436
    Abstract: The direct optical amplifier of the present invention monitors not only a pilot tone signal but also the main signal, and when the pilot tone signal loses relation to the main signal, re-establishes the relation between the level of the pilot tone signal and the average level of the main signal such that the pilot tone signal again functions as the reference light of the main signal. The average level of the true main signal from which a noise component has been eliminated is determined by means of a wavelength analyzer. The average level of the true main signal that has been determined is correlated with the level of a pilot tone signal that is monitored, whereby the pilot tone signal again functions as the reference light of the main signal. The monitored pilot tone signal is then controlled to obtain the desired average level of the true main signal.
    Type: Application
    Filed: July 16, 2003
    Publication date: January 22, 2004
    Inventor: Hideshi Yoshida
  • Publication number: 20040005151
    Abstract: An approach for providing transmission level control in an optical network having an amplifier chain is disclosed. An optical communications system includes a gateway network element configured to receive an amplifier requirement from a host. The system also includes a network element communicating with the gateway network element over an optical amplifier chain, the network element being configured to receive the amplifier requirement from the gateway network element, and to adjust transmission power level in response to the amplifier requirement (e.g., error rate information including Signal-to-Noise (S/N) ratio, bit error rate (BER), and/or Quality (Q) value).
    Type: Application
    Filed: July 2, 2002
    Publication date: January 8, 2004
    Inventor: Donald Pitchforth
  • Patent number: 6661975
    Abstract: An optical communication system (20) is provided for transmitting a multi-rate data signal between a transmitter (22) and a receiver (24) in a power efficient manner. The optical communication system (20) includes an optical source (32) that supplies an optical carrier signal; an encoder (44) that receives and encodes a data signal; an external phase modulator (42) that modulates the optical carrier signal with the encoded data signal, such that the modulator (42) varies the duty factor of the modulated optical signal based on the encoded data signal; and an optically saturated erbium doped fiber amplifier (36) that amplifies the modulated optical signal prior to transmission by the transmitter (22). In accordance with the present invention, the modulation scheme of the optical communication system (20) varies the duty cycle of the modulation to attain power efficiency during periods of low data demand.
    Type: Grant
    Filed: March 10, 2000
    Date of Patent: December 9, 2003
    Assignee: Northrop Grumman Corporation
    Inventors: Dennis M. Hall, Raymond K. DeLong, Donald G. Heflinger, Peter M. Tanner
  • Publication number: 20030202799
    Abstract: A monitor apparatus is configured to monitor optical performance in an optical fiber or an optical network. A tap is coupled to the optical fiber or optical network, and a signal input fiber. An angle-tuned solid Fabry-Perot etalon filter member is coupled to the tap. The Fabry-Perot etalon filter member includes an angle tuned solid Fabry-Perot etalon for the signal input fiber, and a calibration etalon for a reference input fiber. The Fabry-Perot etalon is associated with a first portion of a substrate, and the calibration etalon is associated with a second portion of the substrate. A first detector is positioned to receive a signal wavelength that travels through the angle tuned solid Fabry-Perot etalon filter. A second detector is positioned to receive a single wavelength reference that travels through the calibration etalon.
    Type: Application
    Filed: April 29, 2002
    Publication date: October 30, 2003
    Inventors: Dennis Chi Zhou, Shou-Jong Sheih
  • Publication number: 20030185570
    Abstract: A system for reducing gain ripple of an optical system that includes a set of spans further includes a multiplexing unit and an optical filter. The multiplexing unit multiplexes a plurality of optical signals. The optical filter filters the multiplexed optical signals, prior to transmission of the multiplexed signals over the spans of the optical system, to reduce gain ripple.
    Type: Application
    Filed: March 28, 2002
    Publication date: October 2, 2003
    Inventors: M. Imran Hayee, William Shieh, Thomas Clark
  • Publication number: 20030152388
    Abstract: There is suppressed deterioration of transmission quality resulting from FWM generated in the optical fiber of an optical transmission apparatus which performs wavelength division multiplex transmission. A wavelength division multiplexing optical transmission system is not restricted by a wavelength division multiplex density. Intensity of FWM generated in an optical fiber transmission line for each span is observed by a receiver side to determine intensity of output light to send the span by a sender side, to thereby suppress deterioration of the transmission quality due to the FWM generated in the optical fiber of a WDM optical transmission apparatus.
    Type: Application
    Filed: January 15, 2003
    Publication date: August 14, 2003
    Inventors: Tetsuya Uda, Ryoichi Miyake, Takeshi Nakada, Yoshimasa Kusano, Eiichirou Takizawa
  • Patent number: 6604870
    Abstract: A method of transmitting data signals via an optical fiber between two network elements (14, 36, 43, 56) in a digital data transmission network comprises using a transmission protocol, wherein, in addition to said data signals, first control and/or monitor signals in the form of overhead signals are transmitted. An optical fiber amplifier (23) is inserted in the optical fiber between the two network elements. Additionally, second control and/or monitor signals in a format corresponding to said overhead signals are transferred between the optical fiber amplifier and at least one of the two network elements. An amplifier unit (22, 48) comprising an optical fiber amplifier (23) is adapted to be inserted in an optical fiber for the transmission of data signals between two network elements (14, 36, 43, 56) in such a data transmission network.
    Type: Grant
    Filed: July 27, 2001
    Date of Patent: August 12, 2003
    Assignee: Tellabs Denmark A/S
    Inventor: Henrik Hørlyck