| Class / Patent application number | Description | Number of patent applications / Date published |
|---|
| 398081000 | Dispersion compensation | 65 |
| 20080199182 | Transmission system and transmission method - 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. | 08-21-2008 |
| 20080219667 | OPTICAL COMMUNICATION SYSTEM AND DISPERSION-COMPENSATING OPTICAL FIBER - With this scheme, there is provided an optical communication system and a dispersion-compensating optical fiber with which a long-haul optical signal transmission is possible by making use of the low optical nonlinearity and the low transmission loss characteristic of the photonic bandgap optical fiber. | 09-11-2008 |
| 20080273879 | Optical Transmission System and Method for Compensating Wavelength Dispersion of Main Signal By Multiplexing Dispersion-Free Control Signal - At the transmit end of an optical transmission link, a main signal and a control signal are multiplexed into an optical multiplex signal and forwarded to the link. The frequency of the control signal is much lower than the frequency of the main signal so that the control signal is not affected by the wavelength dispersion effect of the transmission link. A the receive end of the link, the optical multiplex signal is demultiplexed, recovering the main signal and the control signal. An amount of compensation necessary to compensate for the wavelength dispersion of the recovered main signal is detected and used in combination with the dispersion-free control signal to compensate for the wavelength dispersion of the optical main signal. The main signal and the control signal may either be frequency division multiplexed or wavelength division multiplexed into the optical multiplex signal. | 11-06-2008 |
| 20090067844 | TELECOMMUNICATIONS TRANSPORT METHODS AND SYSTEMS FOR EXTENDED REACH LOW DIFFERENTIAL LATENCY - Systems and methods for extended reach low differential latency optical networking with optical amplifiers and dispersion compensation modules configured to minimize latency between transmit and receive paths are provided. Additionally, systems and methods are provided for incorporating absolute time references wherein the relative accuracy of clock time between various servers used in various multi-site enterprises is required. The transport systems and methods are used in conjunction with low differential latency systems. The transport systems and methods provide that the differential latency between transmit and receive directions is maintained within about +/−5 microseconds of the transmit/receive path differential delay requirement in order to perform within the overall parameters of the low differential latency system architecture. | 03-12-2009 |
| 20090074417 | Method and System for Compensating for Optical Dispersion in an Optical Signal - 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. | 03-19-2009 |
| 20090080894 | Chromatic dispersion compensating apparatus - In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero. | 03-26-2009 |
| 20090097850 | Optical Communications System - In an optical communications link, an optical system including: at least a first input port for delivering an optical signal travelling in the communications link, the optical signal including a plurality of wavelength channels, the channels being utilized for carrying optical information over an optical data link; a dispersive element for spatially separating the wavelength channels; an active optical-phase element; and a plurality of optical manipulation elements for directing the spatially separated channels between the dispersive element and the optical phase element wherein, the optical phase element independently modifies the phase of predetermined ones of the wavelength channel in a predetermined and decoupled manner for substantial compensation of signal degradation effects imparted to the wavelength channels by said communications link. | 04-16-2009 |
| 20090123153 | PHASE SHIFT KEYED HIGH SPEED SIGNALING - Fiber optic transmission technologies that allow DPSK or even higher order PSK to be performed at 20 gigabits per second per channel or even higher bit rates in a WDM (e.g., DWDM) wavelength multiplexed channeling environment. The technology employs pre-compensation of chromatic error dispersion such for each of most, if not all, channels have a portion of minimum absolute accumulated dispersion that occurs somewhere within the length (perhaps at the mid-point) of the optical channel. Post-compensation is then employed at the receiver to reduce or even potentially eliminate the chromatic dispersion. The technology allows for reduced bit error rates at high bit rates over even very long haul (e.g., trans-oceanic submarine or long terrestrial) optical fiber links, and for all channels. | 05-14-2009 |
| 20090162068 | POLARIZATION MODE DISPERSION COMPENSATION CIRCUIT - An object of the present invention is to realize a compensation circuit which can cope with rapidly fluctuating polarization mode dispersion, and the configuration thereof is a polarization dispersion compensation circuit for compensating polarization mode dispersion which takes place when a signal propagates on a transmission path, characterized by comprising: a front-end compensation part configured as a transversal filter for shaping a waveform subjected to polarization mode dispersion; and a data tracking/recovery part including a PLL-type data recovery circuit having a loop frequency band higher than the fluctuation frequency of polarization mode dispersion, and that tracks the temporal fluctuation of the polarization mode dispersion to recover data. | 06-25-2009 |
| 20090190930 | METHOD AND ARRANGEMENT FOR POLARIZATION MODE DISPERSION MITIGATION - In an optical transmission system including a transmitter Tx and a receiver Rx connected via a fiber link F, where the receiver Rx is adapted to utilize Forward Error Correction (FEC) on received signals, a polarization scrambler is provided at the transmitter Tx to scramble the polarization state of a transmitted signal, a polarization delay line is provided at the receiver Rx for controlling the polarization mode dispersion induced distortion of a received signal, a feedback unit is provided at the receiver Rx for providing a feedback signal based on at least part of the received signal, and at least one polarization controller interconnects the fiber link F and the polarization delay line. The power controller is operable based on the feedback signal to mitigate the polarization mode dispersion of the signal. | 07-30-2009 |
| 20090202248 | WAVELENGTH DIVISION MULTIPLEXING SYSTEM, METHOD AND DEVICE FOR ITS RESIDUAL DISPERSION COMPENSATION - The present invention provides a wavelength division multiplexing system and a method and device for its residual dispersion compensation, wherein the device for residual dispersion compensation of wavelength division multiplexing system comprises: a performance parameter detecting device for receiving and detecting performance parameter of receiving terminal optical signal and sending detecting result of the performance parameter to a central control device; the central control device for deciding a dispersion regulating mode of a tunable dispersion compensator according to the detecting result of the performance parameter and sending the dispersion regulating mode to a tunable dispersion compensator control device through control signaling; and the tunable dispersion compensator control device for receiving the control signaling sent by the central control device and adjusting dispersion compensation amount of the tunable dispersion compensator according to the control signaling in order to make residual dispersion of wavelength channels to satisfy requirements of dispersion tolerance of an optical receiver. Therefore, the present invention optimizes residual dispersion of each channel and solves the problem of transmission performance deterioration caused by residual dispersion of long distance optical transmission system. | 08-13-2009 |
| 20090208216 | Dispersion compensation - A dispersion compensation system comprises a detector for receiving an optical input signal and a compensator for processing the detector outputs and re-constituting the original signal. The detector generates at least two signals which depend on the instantaneous amplitude and frequency of the distorted signal in different ways, and the compensator electrically processes the detector outputs. The detector comprises a wavelength selective device (such as an asymmetric MZI) and two or more opto electronic detectors providing the electrical signals. The detector subtracts outputs of the MZI to provide frequency information and sums MZI outputs to provide amplitude information. The detector may have a dedicated amplitude detector. The compensator may have a local oscillator which is modulated by amplitude and phase or frequency information of the detector output signals, and the local oscillator may operate in the range of 11 to 100 GHz. | 08-20-2009 |
| 20090214215 | Electronic Post-Compensation of Optical Transmission Impairments Using Digital Backward Propagation - Systems and method of compensating for transmission impairment are disclosed. One such method comprises: receiving an optical signal which has been distorted in the physical domain by an optical transmission channel; and propagating the distorted optical signal backward in the electronic domain in a corresponding virtual optical transmission channel. | 08-27-2009 |
| 20090220239 | METHODS AND APPARATUS FOR OPTICAL TRANSMISSION OF DIGITAL SIGNALS - 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 ( | 09-03-2009 |
| 20090220240 | HIGH-SPEED BANDPASS SERIAL DATA LINK - The present invention relates to a method and system for high-speed bandpass serial data communication. A driver receives at least one data signal and generates a bandpass data signal for transmission through a bandpass waveguide interconnect. The bandpass data signal is launched into the bandpass waveguide interconnect using a first adaptor and extracted therefrom after transmission using a second adaptor. A receiver connected to the second adaptor recovers the at least one data signal from the extracted bandpass data signal. A dispersion compensation circuit receives one of the at least one data signal and the bandpass data signal and information indicative of a phase response of the bandpass waveguide interconnect and dispersion compensates the one of the at least one data signal and the bandpass data signal by compensating the phase response of the bandpass waveguide interconnect. | 09-03-2009 |
| 20090220241 | CHROMATIC DISPERSION COMPENSATION DESIGNING METHOD IN OPTICAL NETWORK AND A SYSTEM THEREOF - A residual chromatic dispersion target value at a terminal node is set for each wavelength path, and also, candidates of a dispersion compensation amount settable in each chromatic dispersion compensation module on an optical network are set, and further, computation processing is executed for selecting the dispersion compensation amount in each chromatic dispersion compensation module from the candidates so that the sum of errors between the residual chromatic dispersion amounts and the set residual chromatic dispersion target values at the terminal nodes for all of wavelength paths becomes minimum. As a result, for each wavelength path on the optical network, the dispersion compensation amount in each chromatic dispersion compensation module can be designed in optimum so as to satisfy the desired optical signal quality at the terminal node, while considering the residual chromatic dispersion during the transmission. | 09-03-2009 |
| 20090252497 | Method and apparatus for compensating for polarization mode dispersion (PMD) - Current optical networks are engineered to handle amplifier noise and chromatic dispersion. Polarization mode dispersion occurs in optical networks due splitting of the light energy of a pulse propagating in a fiber into two modes. Compensating for polarization mode dispersion is a difficult and expensive task and hence only few commercial systems have been deployed to deal with this issue. A polarization mode dispersion compensation module according to an example embodiment of the present invention compensates for polarization mode dispersion by determining a performance metric related to an error rate of an optical signal in at least one polarization mode in a filtered state. Based on the performance metric, a control vector is determined to control the optical signal in the at least one polarization mode in the filtered state. The control vector is then applied to a polarization effecting device to compensate for polarization mode dispersion. | 10-08-2009 |
| 20090290879 | WAVELENGTH DISTRIBUTION FOR OPTICAL TRANSPORT - An optical communication system includes logic to communicate using optical channels set outside a fiber zero dispersion zone, and having channel spacing that decreases with increasing distance from the fiber zero dispersion zone. | 11-26-2009 |
| 20090297153 | Four quadrant linearizer - A system includes a laser generator, and a signal distortion generator circuit inline with the laser generator modulation signal and configured to generate distortion vectors in any of four distortion vector quadrants. | 12-03-2009 |
| 20090297154 | Transmission-path-type specifying apparatus and transmission-path-type specifying method - A transmission-path-type specifying apparatus includes an optical filter that extracts a plurality of different wavelength components from light including wavelength components occurring at the time of communication; an optical switch that simultaneously transmits same pulse signals superposed on light of the extracted wavelength components. The apparatus also includes an ASE modulation controlling unit that obtains a delay-time difference among the transmitted pulse signals when arriving at a destination via a transmission path; a characteristic-value calculating unit that calculates a characteristic value of the transmission path corresponding to a reference time varied depending on the obtained delay-time difference and a type of the transmission path; and a fiber-type determining unit that specifies the type of the transmission path based on the calculated characteristic value. | 12-03-2009 |
| 20090317085 | Optical module and dispersion compensator - In an optical module, a lens collects input light to generate a collected beam. A VIPA plate includes a reflective surface for highly reflecting light and a transmissive surface on which a reflection film having a lower reflectivity than the reflective surface is deposited. The VIPA plate causes multiple reflection of the collected beam within an internal area between the reflective surface and the transmissive surface, and emits diffracted light via the transmissive surface. A reflection mirror reflects outgoing light emitted from the transmissive surface to generate return light which returns to the transmissive surface. The reflection film includes a high-reflection film deposited on a portion from which the outgoing light of a high light intensity is emitted and a low-reflection film deposited on a portion from which the outgoing light having a lower light intensity is emitted. | 12-24-2009 |
| 20100021169 | OPTICAL TRANSMISSION SYSTEM AND OPTICAL TRANSMISSION CONTROL METHOD - The present invention is intended to provide an optical transmission system which is applicable not only to a known signal but also to an unknown signal, and has a high reliability at a low cost. A branching device branches an optical transmission output of a transmitter, and transmits the branched signals through different optical transmission channels. A polarization mode dispersion monitor monitors the degree of polarization mode dispersion from the optical transmission channels at the receiving end. A switch control circuit and a switch select a signal which is less affected by a deterioration in quality due to polarization mode dispersion, and outputs the selected signal to receiver 8. In this way, the probability of a deterioration in the quality of a signal due to polarization mode dispersion can be reduced for a transmission signal. | 01-28-2010 |
| 20100021170 | Wavelength Multiplexed Optical System with Multimode Optical Fibers - The present wavelength multiplexed optical system includes a multimode optical fiber that transmits wavelength multiplexed optical signals and a plurality of multimode modal dispersion compensation optical fibers. Each modal dispersion compensation optical fiber can transmit one of the multiplex wavelengths, and each modal dispersion compensation optical fiber has an optimized index profile such that the modal dispersion for the transmitted wavelength is approximately inversely equal to the modal dispersion induced in the multimode optical fiber. The wavelength multiplexed optical system facilitates an increased bitrate without reducing bandwidth. | 01-28-2010 |
| 20100028007 | Optical transmission apparatus - Where add optical signals have k different bit rates, an add controller is connected to k (| 02-04-2010 | |
| 20100098423 | WAVELENGTH DIVISION MULTIPLEXING DEVICE AND METHOD FOR DETECTING INPUT BREAK OF OPTICAL SIGNAL - A wavelength division multiplexing device comprises a detection unit to detect the low-frequency signal in the optical signal; and a control unit to control to make the dispersion compensator perform a compensation operation by determining that the optical signal is being input when a low-frequency signal is detected in the optical signal in the detection unit, and to control to stop a compensation operation of the dispersion compensator by determining that there is an input break of the optical signal when a low-frequency signal is not detected in the optical signal in the detection unit. | 04-22-2010 |
| 20100111536 | Communication network and design method - A communication network includes a starting node that has a variable dispersion compensator that performs dispersion compensation at a variable dispersion compensation amount such that a residual dispersion amount of an optical signal transmitted therethrough becomes a predetermined reference residual dispersion amount; and plural nodes that are subjected to dispersion compensation design using the starting node as a starting point and that include fixed dispersion compensators selected based on the reference residual dispersion amount. | 05-06-2010 |
| 20100129081 | DISTRIBUTED RAMAN AMPLIFIER AND OPTICAL COMMUNICATION SYSTEM - The distributed Raman amplifier monitors an OSNR of each channel in a WDM light which has been propagated through a transmission path to be Raman amplified, and thereafter, is amplified by an optical amplifier in an optical repeating node; judges whether a monitor value of the OSNR is larger or smaller than a previously set target value thereof; and feedback controls a driving state of a pumping light source which supplies a Raman pumping light to the transmission path, based on the judgment result. The optical communication system comprises the above distributed Raman amplifier in each repeating span thereof, and performs a pumping light control of the distributed Raman amplifier corresponding to the repeating span selected based on the OSNR in each distributed Raman amplifier and the monitor result of span loss. As a result, it becomes possible to effectively improve the OSNR of each channel in the WDM light, and also, to reduce the power consumption. | 05-27-2010 |
| 20100135664 | Chromatic dispersion compensating apparatus - In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero. | 06-03-2010 |
| 20100150562 | OPTICAL TRANSMISSION SYSTEM - An optical transmission system in which a plurality of optical signals each having a different wavelength are transmitted via a single optical fiber, includes: a first dispersion compensator configured to compensate for wavelength dispersion based on a single wavelength of a plurality of signals transmitted via the optical fiber; a demultiplexer connected to the first dispersion compensator, splitting signals output from the first dispersion compensator into different channels according to their wavelengths, and outputting the same; and a plurality of second dispersion compensators connected to each channel split by the demultiplexer, and compensating for the wavelength dispersion of the mutually different wavelength optical signals. | 06-17-2010 |
| 20100150563 | WAVELENGTH DIVISION MULTIPLEXING TRANSMISSION DEVICE AND WAVELENGTH DIVISION MULTIPLEXING TRANSMISSION METHOD - The power level of a wavelength division multiplexed optical signal is detected by a detection unit. When the power level of the optical signal detected by the detection unit is equal to or lower than a first threshold, the coupling direction of an attenuation unit for controlling the coupling direction for the ports of the optical signal is controlled in the direction orthogonal to the array direction of the ports. When the power level of the optical signal exceeds a second threshold, the coupling direction of the attenuation unit is controlled in the array direction of the ports. | 06-17-2010 |
| 20100158532 | WDM TRANSMISSION APPARATUS, OPTICAL ADD-DROP MULTIPLEXER AND WDM TRANSMISSION METHOD - There is provided a WDM transmission apparatus including a calculator being operable to calculate an optical signal level of a wavelength after wavelength demultiplexing based on information of OSNR, an amplifier controller being operable to compensate for the optical signal levels of all the wavelengths after wavelength demultiplexing to become a target level based on an optical signal level calculated by the calculator, and an deviation corrector being operable to correct a deviation of an optical signal level between each wavelength based on the optical signal level calculated by the calculator. | 06-24-2010 |
| 20100166426 | OPTICAL SIGNAL PROCESSING DEVICE - An optical signal processing device includes a waveform width widening unit configured to widen a waveform width of an optical signal; and an optical limiter circuit, to which the optical signal the waveform width of which is widened is input, configured to suppress an intensity of the optical signal in a region where an input intensity and an output intensity are not proportional. | 07-01-2010 |
| 20100183310 | DISPERSION COMPENSATOR - Conventional dispersion compensators were not sufficient to satisfy a demand to set a different dispersion value for each WDM wavelength in a ring-mesh type network that utilizes wavelength selective switches or the like. The devices were insufficiently reduced in size and power consumption and used with difficulty to change dispersion characteristics for each wavelength flexibly in a simple manner. A dispersion compensator of the present invention uses general-purpose optical components including a spatial light modulator for providing discrete phases to set appropriately the relationship between the focusing beam radius and the spatial light modulator pixel, thereby providing various dispersion compensation characteristics. Attention is focused on the correspondence between multiple pixels on the spatial light modulator providing discrete phases and a communication channel band, thereby allowing for changing the flexible dispersion characteristics and realizing the setting of an independent dispersion value for each WDM wavelength. | 07-22-2010 |
| 20100221013 | OPTICAL TRANSMISSION APPARATUS, WAVELENGTH DIVISION MULTIPLEXING OPTICAL COMMUNICATION SYSTEM AND OPTICAL TRANSMISSION METHOD - An optical transmission apparatus for suppressing deterioration of transmission quality due to XPM in a wavelength division multiplexing optical communication system in which an intensity modulation optical signal and a phase modulation optical signal exist in a mixed form. The apparatus has an intensity inversion signal light output section which outputs light having an intensity pattern obtained by inverting intensity changes of the intensity modulation optical signal near a wavelength of the intensity modulation optical signal in arrangement on wavelength axis of optical wavelengths that can be multiplexed as a wavelength division multiplexed signal as intensity inversion signal light, and a wavelength division multiplexed optical signal output unit which wavelength-division-multiplexes the intensity modulation optical signal, the phase modulation optical signal and light from the intensity inversion signal light output section and outputs a wavelength division multiplexed optical signal. | 09-02-2010 |
| 20100221014 | OPTICAL FIBER TRANSMISSION SYSTEM AND METHOD - An optical fiber transmission system including: a first transmission-line optical fiber to input first wavelength signal light output from a transmitter, and to change a waveform of the signal light; an optical coupler to combine the first wavelength signal light that has been propagated through the first transmission-line optical fiber with second wavelength pumping light; an optical limiter to input coupled light output from the optical coupler, saturating a gain as power of the coupled light increases using a nonlinear optical medium, thereby suppressing an optical noise component included in the coupled light, and to output signal light including the first wavelength optical component obtained from the nonlinear optical medium; and a second transmission-line optical fiber to input to a receiver after signal light output from the optical limiter is input and a waveform change by the first transmission-line optical fiber in the signal light is compensated for. | 09-02-2010 |
| 20100239260 | OPTICAL TRANSMISSION APPARATUS, OPTICAL COMMUNICATION METHOD, AND OPTICAL COMMUNICATION SYSTEM - An optical transmission apparatus and method thereof is provided. The optical transmission apparatus includes transmission units configured to transmit lights having different wavelengths, a multiplexing unit configured to multiplex lights transmitted from the transmission units, and a controller configured to control wavelengths of the lights, where the controller includes a wavelength spacing processing unit that controls a spacing between the wavelengths on the basis of reception state information of an apparatus that has received the multiplexed light. | 09-23-2010 |
| 20100239261 | Electronic Compensation of Impairments Using Wavelet Filters for Backward Propagation - Systems and methods of compensating for transmission impairment over an optical transmission channel are disclosed. The optical transmission channel includes an optical fiber and an optical amplifier. One such method includes: receiving an optical signal which has been distorted in the physical domain by an optical transmission channel; and solving a non-linear Schrödinger equation (NLSE) using a split-step Fourier Method (SSFM). The NLSE describes a virtual optical fiber corresponding to the optical fiber. The SSFM implements a linear operator with a wavelet-based FIR filter. | 09-23-2010 |
| 20100239262 | Compensation of Optical Transmission Impairments Using Digital Backward Propagation - Systems and method of compensating for transmission impairment are disclosed. One such method comprises receiving a wavelength-division multiplexed optical signal. The received optical signal has been distorted in the physical domain by an optical transmission channel. The method further comprises propagating the distorted optical signal backward in the electronic domain in a corresponding virtual optical transmission channel. The backward propagation fully compensates for fiber dispersion, self-phase modulation, and cross-phase modulation (XPM) and partially compensates for four-wave mixing (FWM). | 09-23-2010 |
| 20100284695 | PRE-COMPENSATION METHOD FOR DELAYS CAUSED BY OPTICAL FIBER CHROMATIC DISPERSION, MULTI-SUB-CARRIER SIGNAL GENERATOR APPLYING THE METHOD, AND TRANSMITTER OF OPTICAL-OFDM SYSTEM APPLYING THE SIGNAL GENERATOR - A pre-compensation method for delays caused by optical fiber chromatic dispersion, a multi-sub-carrier signal generator applying the method, and a transmitter applying the signal generator are applicable to an optical orthogonal frequency-division multiplexing (OFDM) system. The pre-compensation method includes receiving a plurality of pre-compensation values, in which the pre-compensation values correspond to sub-carriers; and transmitting the sub-carriers after delaying the sub-carriers by time of the corresponding pre-compensation values. The delay time between the sub-carriers is estimated at a receiver end and a pre-compensation value of the transmitter is set according to the delay time. The transmitter delays the pre-compensation values respectively when transmitting the respective sub-carriers. Therefore, the respective sub-carriers are able to reach a receiver at nearly the same time, thereby achieving a purpose of pre-compensating for the delays caused by optical fiber chromatic dispersion. | 11-11-2010 |
| 20100329683 | System, Method and Apparatus for Coherent Optical OFDM - Digital compensation of chromatic dispersion (CD) effect experienced by optical orthogonal frequency-division multiplexed (OFDM) signal in fiber transmission is provided in the frequency domain using a Fast Fourier Transform/Inverse Fast Fourier Transform (FFT/IFFT) pair with equal length of digital samples prior to OFDM receiver signal processing, wherein the equal length is larger than the length of a FFT used for OFDM subcarrier demultiplexing of the received signal. The OFDM signal processing is independent of fiber CD, so small guard-interval (GI) can still be used to achieve high spectral efficiency even under the experience of large CD. The GI need only to be large enough to accommodate other effects such as polarization-mode dispersion. The length of an IFFT used for OFDM subcarrier multiplexing, as well as the FFT for OFDM demultiplexing can be sufficiently small so subcarrier spacing is sufficiently large to tolerate typical frequency offsets between the transmitter laser and the optical local oscillator. | 12-30-2010 |
| 20110026927 | Transmission apparatus, transmission system, and method of communication - A transmission apparatus is provided. The transmission apparatus in a transmission system that performs dispersion compensation on a transmission line includes a receiver, an information collection unit and a chromatic dispersion providing unit. The receiver receives a wavelength division multiplexing optical signal for each wavelength from the transmission line. The information collection unit collects information regarding a reception method applied to each wavelength of the optical signal received by the receiver, as reception method information. The chromatic dispersion providing unit provides respective chromatic dispersion amounts different from each other to an optical signal received using a digital coherent reception method and an optical signal received using a reception method other than the digital coherent reception method, based on the information regarding a reception method collected by the information collection unit. | 02-03-2011 |
| 20110052198 | OPTICAL TRANSMISSION DEVICE, TRANSMISSION AND RECEPTION MODULE, OPTICAL TRANSMISSION SYSTEM, AND WAVELENGTH DISPERSION COMPENSATION METHOD IN OPTICAL TRANSMISSION DEVICE - An optical transmission device includes: a variable dispersion compensator to give chromatic dispersion and output an input light, a branching unit to branch the light output from the variable dispersion compensator to a first part and a second part, a reproduction unit to reproduce an electric signal from the first part of the input light, a monitor unit to perform reproducing processing on the electric signal from the second part of the input light, control the variable dispersion compensator based on a result of the reproducing processing, and has a sensitivity to a variation of the chromatic dispersion which is higher than the sensitivity to the variation of the chromatic dispersion of the reproduction unit. | 03-03-2011 |
| 20110097087 | DISTINCT DISPERSION COMPENSATION FOR COHERENT CHANNELS - An optical assembly in an optical link coupling two optical terminals. The optical assembly receives and demultiplexes two groups of optical wavelength channels which are each treated separately as far as dispersion compensation and discrete amplification are concerned. The optical assembly then multiplexes the two groups back into the same fiber for further transmission. For instance, one group of optical wavelength channels may each be coherent channels, and subject to no dispersion in the optical assembly, while the other group may contain non-coherent channels, which are subject to dispersion compensation in the optical assembly. | 04-28-2011 |
| 20110097088 | INTRODUCTION-SIDE DISPERSION SHIFTING OF CHANNELS - The mixing of coherent optical wavelength channels with non-coherent optical wavelength channels. Before mixing, a dispersive element introduces dispersion into the coherent optical wavelength channels and/or into the non-coherent optical wavelength channels such that the dispersion map of the coherent optical wavelength channels is different than the dispersion map of the non-coherent optical wavelength channels. By allowing the coherent channels to have a different dispersion map, the dispersion map may be moved further from the zero dispersion point, which can degrade coherent detection. Accordingly, coherent optical channels and non-coherent optical channels may be transmitted effectively over the same optical link. | 04-28-2011 |
| 20110116800 | NONLINEARITY COMPENSATION IN A FIBER OPTIC COMMUNICATIONS SYSTEM - An optical communications link is described, comprising first and second fiber lines in substantial scaled translational symmetry by a common scaling factor with respect to a second-order dispersion coefficient profile (oppositely signed) and with respect to at least one of a loss/gain coefficient profile and a nonlinear coefficient-power product profile for facilitating progressive compensation along the second fiber line of at least one nonlinearity introduced along the first fiber line. | 05-19-2011 |
| 20110164879 | Compact Multi-Port Optical Signal Processor - In a method and system to fabricate a compact optical device, a periodic group-delay device (PGDD) includes N optical input ports, N being a positive integer number, each port being configured to include one or more wavelength-division- multiplexing (WDM) channels; N corresponding optical output ports, each port being configured to include one or more WDM channels. The PGDD also includes a first slab waveguide region (FSWR) coupled to the N optical input ports, a second slab waveguide region (SSWR) coupled to the said N optical output ports, a first optical grating coupled to the FSWR, a second optical grating coupled to the SSWR, and; a third slab waveguide region (TSWR) coupled to at least one of the first and second optical gratings. The TSWR is configured to provide a configurable amount of dispersion to the N optical output ports. Optical signals carried by each WDM channel are processed concurrently and independently. | 07-07-2011 |
| 20110188861 | REDUCING OPTICAL SERVICE CHANNEL INTERFERENCE IN PHASE MODULATED WAVELENGTH DIVISION MULTIPLEXED (WDM) COMMUNICATION SYSTEMS - A system for transmitting a plurality of data channels and an optical service channel through an optical fiber link of a Wavelength Division Multiplexed (WDM) optical communications system. The system comprises a first transmitter at a first end of the optical fiber link, for transmitting the data channels as a wavelength division multiplexed optical signal through the optical fiber link in a first direction. A second transmitter is connected at a second end of the optical fiber link, for transmitting the optical service channel through the optical fiber link in a second direction opposite to the first direction. | 08-04-2011 |
| 20110211840 | REMOTELY SETTABLE CHROMATIC DISPERSION ROBUSTNESS FOR DENSE WAVE DIVISION MULTIPLEXING INTERFACES - An apparatus for transmitting signals in a telecommunications network includes a light source that generates an optical signal for encoding information transmitted from the apparatus over a light path of the telecommunications network, a modulator configured for controlling the optical signal to generate chirped optical pulses of the optical signal, the chirped optical pulses having a first frequency spectrum controlled by the modulator, such that when the pulses are transmitted from the apparatus and received at an end of the first light path the pulses have a chromatic dispersion penalty that is less than a predetermined penalty. Modulation control circuitry receives instructions from a remote controller and, in response to the instructions, controls the modulator such that the chirped optical pulses have a second frequency spectrum controlled by the modulator, such that when the pulses are transmitted from the apparatus and received at an end of a second light path of the telecommunications network the pulses have a chromatic dispersion penalty that is less than a predetermined penalty. | 09-01-2011 |
| 20110236023 | SIGNAL LIGHT PROCESSING APPARATUS, LIGHT TRANSMISSION APPARATUS, WAVELENGTH SELECTION SWITCH, WAVELENGTH DIVISION MULTIPLEXING TRANSMISSION SYSTEM, AND SIGNAL LIGHT PROCESSING METHOD - A signal light processing apparatus includes a first wavelength selection switch, a dispersion compensator, and a second wavelength selection switch. The first wavelength selection switch divides an input wavelength-multiplexed signal light into signal lights of each wavelength and outputs the signal lights from a first output port or a second output port in accordance with wavelengths of the divided signal lights. The dispersion compensator compensates dispersion compensation on the signal light output from the first output port by the first wavelength selection switch. The second wavelength selection switch combines the signal light on which dispersion compensation is compensated by the dispersion compensator and the signal light output from the second output port by the first wavelength selection switch. | 09-29-2011 |
| 20110318010 | DISPERSION SLOPE COMPENSATION METHOD AND APPARATUS - Embodiments of the present invention disclose a dispersion slope compensation method and apparatus, which relates to the field of communication. The method includes: performing dispersion slope compensation on a main optical channel; and dividing the main optical channel into a preset number of sub-bands, and performing the dispersion slope compensation on each sub-band. The apparatus includes: a main optical channel compensation module, a band-division module and a compensation module. The method and apparatus have the following beneficial effects. The dispersion slope compensation is performed on the main optical channel, and then band division is performed on the main optical channel after the compensation, and the dispersion slope compensation is performed on each sub-band. The configuration of the method is simple, the number of the sub-bands is few, and the cost is dramatically reduced as compared with the dispersion slope compensation method in the prior art. | 12-29-2011 |
| 20120002968 | SYSTEM AND METHODS FOR QUANTUM KEY DISTRIBUTION OVER WDM LINKS - A system and a method for quantum key distribution between a transmitter and a receiver over wavelength division multiplexing (WDM) link are disclosed. The method includes providing one or more quantum channels and one or more conventional channels over the WDM link; assigning a different wavelength to each of the one or more quantum channels and each of the one or more conventional channels; transmitting single photon signals on each of the one or more quantum channels; and transmitting data on each of the one or more conventional channels. The data comprises either conventional data or trigger signals for synchronizing the transmission of the single photon signals on the quantum channels. All channels have wavelengths around 1550 nm. The WDM link can be a 3-channel WDM link comprising two quantum channels for transmitting single photon signals and one conventional channel for transmitting conventional data or triggering signals. | 01-05-2012 |
| 20120027412 | Electronic Compensation of Nonlinearity in Optical Communication - In various embodiments, electronic apparatus, systems, and methods include electronic compensation of nonlinearity in optical communication. Additional apparatus, systems, and methods are disclosed. | 02-02-2012 |
| 20120063783 | SYSTEM AND METHOD FOR REDUCING POLARIZATION DEPENDENT LOSS - In accordance with the present disclosure a method for reducing polarization dependent loss experienced by an optical signal comprises monitoring a power level of a polarization multiplexed optical signal. The method further comprises detecting a power spike based on the monitored power. The power spike is induced by misalignment of a polarization component axis of the optical signal with a polarization dependent loss (PDL) axis of one or more network elements. The method further comprises rotating the polarization orientation of the optical signal such that the power spike is reduced. | 03-15-2012 |
| 20120093516 | IN-SERVICE OPTICAL DISPERSION DETERMINING SYSTEM AND METHOD - 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. | 04-19-2012 |
| 20120099867 | WAVELENGTH MULTIPLEXING OPTICAL COMMUNICATION DEVICE AND OPTICAL DISPERSION COMPENSATION METHOD - A wavelength multiplexing optical communication device having an optical dispersion-compensating function compensating for waveform variation of an optical signal due to optical dispersion of a transmission line determines optimum dispersion-compensating values causing a minimum error rate with respect to pre-installed wavelength channels, produces a dispersion map of the transmission line based on optimum dispersion-compensating values, predicts an initial value of a dispersion-compensating value per a newly added wavelength channel with reference to the dispersion map, and starts scanning at the initial value so as to determine an optimum dispersion-compensating value of the newly added wavelength channel, thus updating the dispersion map by adding the optimum dispersion-compensating value of the newly added wavelength channel. Thus, it is possible to set an optimum dispersion-compensating value per each wavelength channel with a high precision, thus shortening the setting time. | 04-26-2012 |
| 20120128362 | COMMUNICATION SYSTEM, DISPERSION SLOPE IMPARTING SECTION, AND METHOD FOR COMMUNICATING - A communication system includes a transmission path through which an optical signal is propagated; and dispersion slope imparting sections provided on a transmitting side and a receiving side of the transmission path, the dispersion slope imparting sections imparting different dispersion and dispersion slope characteristics in accordance with a wavelength band of the optical signal, wherein the dispersion and dispersion slope characteristics imparted by the dispersion slope imparting section on the transmitting side is different from those on the receiving side. | 05-24-2012 |
| 20120155881 | ELECTRONIC DISPERSION COMPENSATION SYSTEM AND METHOD - The invention provides a system and method, for an optical communication network to compensate impairments in the network, using electronic dispersion compensation, said system comprising optical means comprising two or more optical-to-electrical converters for generating at least two electrical signals, comprising amplitude and instantaneous frequency of a received distorted optical signal, and an electrical circuit adapted to perform a full-field reconstruction of the received distorted optical signal using said electrical signals. The system is characterised by a dispersive transmission line circuit with compensation parameters updated at a selected rate to process said full-field reconstructed signal and compensate for coarse chromatic dispersion; and an adaptive electronic equalization circuit with compensation parameters updated at a rate faster than those in the said dispersive transmission line circuit to provide a fine impairment compensation of said reconstructed signals. The system and method of the invention achieves low-cost long-distance transmission, up to 2000 km, while maintaining the fast-adaptive compensation capability and provide a method for transparent long-haul and metro-optical networks. | 06-21-2012 |
| 20130011140 | SUPPRESSION OF NON-LINEAR EFFECTS IN LOW DISPERSION OPTICAL FIBERS - Consistent with the present disclosure, chromatic dispersion is introduced into an optical communication path including multiple segments or spans of dispersion shifted fiber (DSF). The chromatic dispersion generates phase mismatching between optical signals propagating along the optical communication path, i.e., the optical signals are decorrelated, such that mixing products are reduced inmagnitude, and the noise attributable to four wave mixing is correspondingly reduced. | 01-10-2013 |
| 20130183041 | SIGNAL RECEIVING METHOD BASED ON MICROWAVE PHOTONICS TECHNOLOGIES - A microwave photonics based signal receiving device includes a signal generation module, a first Mach-Zehnder modulator, a dispersion module, a second Mach-Zehnder modulator, and a signal conversion module. The signal receiving device simplifies a structure of the signal receiving device by adopting quadrature demodulation. The signal receiving device demodulates a high-order modulation signal and flexibly adjusts a microwave carrier frequency. | 07-18-2013 |
| 20140079401 | WAVELENGTH-DIVISION MULTIPLEXING OPTICAL COMMUNICATION SYSTEM AND METHOD FOR MEASURING OPTICAL PERFORMANCE OF AN OUTPUT SIGNAL FOR THE SYSTEM - A wavelength-division multiplexing optical communication system and a method for measuring optical performance of an output signal for the system. The optical communication system includes: a service-provider device; a local node; and a plurality of subscriber devices. The service-provider device includes: a plurality of first optical transceivers; a first optical multiplexer/demultiplexer (OD/OM) connected to the plurality of first optical transceivers; and a seed-light source providing seed light. Each subscriber device includes a second optical transceiver. The local node connects the service-provider device and the plurality of subscriber devices to each other using a DWDM link comprising: a second multiplexer/demultiplexer (OD/OM); and a single-mode optical fiber for transmission. Here, the optical intensity of an output signal of the second optical transceiver is determined by compensating for the value of the loss caused when the output signal passes through the second OD/OM of the local node. | 03-20-2014 |
| 20140199076 | DIGITAL NON-LINEAR COMPENSATION IN OPTICAL COMMUNICATION SYSTEMS - Systems, devices and techniques for processing an optical signal transmitted from a source over a transmission medium having a length L and performing compensation of non-linear distortions include formulating the compensation as a digital back propagation algorithm by logically dividing the length L into N steps and compensating non-linear distortions for each step as a function of an attenuation adjusting constant parameter that can be selected from a range between 0.3 and 0.7. | 07-17-2014 |
| 20150104179 | Wavelength Stabilizer For TWDM-PON Burst Mode DBR Laser - An optical network unit (ONU) comprising a media access controller (MAC) configured to support biasing a laser transmitter to compensate for temperature related wavelength drift receiving a transmission timing instruction from an optical network control node, obtaining transmission power information for the laser transmitter, estimating a burst mode time period for the laser transmitter according to the transmission timing instruction, and calculating a laser phase fine tuning compensation value for the laser transmitter according to the burst mode time period and the transmission power information, and forwarding the laser phase fine tuning compensation value toward a bias controller to support biasing a phase of the laser transmitter. | 04-16-2015 |
| 20150372763 | LASER TRANSCEIVER WITH IMPROVED BIT ERROR RATE - An optical transceiver generally includes an injection locked (IL) laser configured to generate a transmit (Tx) optical signal for transmission over an optical network and a laser driver circuit configured to modulate the IL laser based on a Tx data signal. The Tx data signal may be provided to the optical transceiver for transmission over the optical network. The Tx data signal may include a crossing point level associated with a transition between a first signal level and a second signal level. The optical transceiver may also include a crossing point control circuit configured to apply distortion to the Tx data signal, the distortion to increase the crossing point level. | 12-24-2015 |
| 20160087747 | DENSE WAVELENGTH DIVISION MULTIPLEXING AND SINGLE-WAVELENGTH TRANSMISSION SYSTEMS - A data transceiver module, data transmission system incorporating same and methods related thereto, which include optical transmitters configured to receive an information bearing signal and generate an optical signal having a wavelength different from wavelengths generated by others of the plurality of optical transmitters; optical receivers configured to receive an optical signal having a wavelength matching one of the plurality of optical transmitters and convert it to an information bearing electrical signal; and a four level pulse-amplitude-modulator (PAM4) chip generating a pulse-amplitude-modulated information bearing signal input to at least one optical transmitter of the plurality of optical transmitters and receiving the information bearing from at least one optical receiver of the plurality of optical receivers and converting it to an information signal using pulse amplitude demodulation. Alternative embodiments include coherent-detection-based optical coherent receiver and coherent transmitter. | 03-24-2016 |
| 20160197681 | EFFICIENT PROCESSING OF HIGH DATA RATE SIGNALS WITH A CONFIGURABLE FREQUENCY DOMAIN EQUALIZER | 07-07-2016 |
