Patent application number | Description | Published |
20100080565 | Electronic Wavefront Correction for Free-Space Optical Communications - Systems and methods of electronic wavefront correction are disclosed. An example method receiving an optical signal representing a wavefront traveling along a plurality of propagation paths, and electronically correcting distortion in the wavefront. An example apparatus includes an receiver and an electronic wavefront corrector. The receiver is configured to coherently receive an optical signal representing a wavefront traveling along a plurality of propagation paths. The electronic wavefront corrector is configured to correct phase distortion in the wavefront. | 04-01-2010 |
20110103529 | Estimating Frequency Offset Using A Feedback Loop - According to particular embodiments, a signal communicated from a transmitter to a receiver is received. A frequency offset estimate of the signal is determined. The frequency offset estimate indicates a frequency difference between the transmitter and the receiver. The frequency offset estimate is provided as feedback. A next frequency offset is compensated for according to the feedback. | 05-05-2011 |
20110150479 | Multi-Level Polarization Multi-Level Phase Modulator - An apparatus for use with an optical computation system may comprise a monolithic device with no free space optical components and may include a phase modulator and a polarization modulator. The phase modulator may be configured to receive a beam of light and two digital data streams and operable to modulate the phase of the beam of light to at least four phase states, the at least four phase states representing the two digital data streams. The polarization modulator may be configured to receive two additional digital data streams and the modulated beam of light from the phase modulator and operable to modulate the polarization of the beam of light to at least four polarization states, the at least four polarization states representing the two additional digital data streams. | 06-23-2011 |
20110176813 | Method and System for Electrical Domain Optical Spectrum Shaping - A system is provided for electrical domain optical spectrum shaping. The system may include a laser, a modulator, a first electrical filter, and a second electrical filter. The laser may be configured to output an optical carrier signal. The modulator may be configured to modulate the optical carrier signal to output a modulated optical signal based on a first filtered input signal and a second filtered input signal received by the modulator. The first electrical filter may be configured to filter a first input signal to produce the first filtered input signal. The second electrical filter may be configured to filter a second input signal to produce the second filtered input signal. | 07-21-2011 |
20110243557 | METHOD AND SYSTEM FOR REDUCING CROSS-PHASE MODULATION IN AN OPTICAL SIGNAL - A method for reducing cross-phase modulation in an optical signal includes receiving an optical signal comprising a plurality of channels, wherein the information being communicated in a first set of one or more of the channels is modulated using one or more single-polarization modulation techniques and wherein the information being communicated in a second set of one or more of the channels is modulated using one or more dual-polarization modulation techniques. The method also includes splitting the optical signal into at least a first copy of the optical signal and a second copy of the optical signal and terminating the second set of channels in the first copy. Furthermore, the method includes applying a differential group delay to the second copy, the differential group delay introducing a walk-off between symbols communicated in a first polarization component of the second set of channels and the symbols of a second polarization component of the second set of channels. In addition, the method includes terminating the first set of channels in the second copy, combining the first set of channels in the first copy and the second set of channels in the second copy, and forwarding the combined channels. | 10-06-2011 |
20120014692 | SYSTEM AND METHOD FOR CROSS-PHASE MODULATION NOISE REDUCED TRANSMISSION IN HYBRID NETWORKS - In one embodiment, a method for receiving optical signals includes receiving a first set of one or more signals and a second set of one or more signals, determining a block length used to process the first set of signals, and processing the first set of signals using the block length. The first set of signals and the second set of signals are separated by a guard band. The block length is based upon the width of the guard band. | 01-19-2012 |
20120063768 | METHOD AND SYSTEM FOR CANCELLATION OF CHROMATIC DISPERSION COMBINED LASER PHASE NOISE - Methods and systems are provided for cancellation of chromatic dispersion combined laser phase noise. A method may include measuring a differential of laser phase noise using two optical pilot signals, the pilot signals each having a different optical frequency, or using an optical carrier and a pilot signal. The method may also include determining an approximate laser phase noise present in an optical system based on the measured differential of laser phase noise. The method may further include compensating for laser phase noise based on the determined approximate laser phase noise. | 03-15-2012 |
20120063781 | SYSTEM AND METHOD FOR REDUCING POLARIZATION DEPENDENT LOSS CROSS-TALK EFFECTS - In accordance with the present disclosure a system for reducing polarization dependent loss (PDL) of an optical signal comprises a delay module coupled to one or more PDL inducing network elements of an optical network. The delay module is configured to time interleave a first polarization component with respect to a second polarization component of the optical signal. The time interleaving reduces interference caused by cross-talk components associated with the first and second polarization components and induced by the PDL of the PDL inducing elements. | 03-15-2012 |
20120082458 | MULTI-WAVELENGTH TRANSPONDER WITH WAVELENGTH DIVISION MULTIPLEXING MODULES - According to one embodiment, a system for transmitting an optical signal comprises a traffic distribution circuit configured to distribute traffic to a plurality of wavelength division multiplexer (WDM) modules. The system further comprises a first WDM module and a second WDM module. The first and second WDM modules each comprise a plurality of tunable optical transmitters, with each transmitter associated with a different wavelength band of a plurality of wavelength bands. Each transmitter in the first and second WDM modules is also tuned to transmit optical signals in channels included within the associated wavelength band of the transmitter. The first and second WDM modules each comprise a multiplexer configured to combine the optical signals transmitted from the plurality of transmitters into optical signals. The system further comprises a cyclic multiplexer configured to combine the optical signals from the first and second WDM modules into an optical output signal. | 04-05-2012 |
20120148232 | METHOD AND SYSTEM FOR COMPENSATION OF LASER PHASE/FREQUENCY NOISE IN AN OPTICAL DEVICE - In accordance with embodiments of the present disclosure, a method for compensation of noise in an optical device is provided. The method may include calculating noise present in an optical carrier signal. The method may also include generating quadrature amplitude modulation input signals, the quadrature amplitude modulation input signals each including a term for compensation of the noise based on the calculated noise. The method may further include modulating the optical carrier signal to generate a modulated optical signal based on quadrature amplitude modulation input signals. | 06-14-2012 |
20120263455 | METHOD AND SYSTEM FOR CALCULATING SPECTRUM GRANULARITY IN FLEXIBLE GRID OPTICAL NETWORKS - In accordance with embodiments of the present disclosure, a method may include determining individual spectrum requirements for each of a plurality of signals to be communicated in an optical network, wherein a first signal of the plurality of signals has a first spectrum requirement and a second signal of the plurality of signals has a second spectrum requirement. The method may also include calculating a minimum spectrum granularity based on the individual spectrum requirements. The method may further include assigning each particular signal a channel spectrum equal to an integer multiple of the minimum spectrum granularity. | 10-18-2012 |
20120328286 | System and Method for Calculating Utilization Entropy - A system and method are provided for monitoring traffic in a network comprising a plurality of links, wherein each of the plurality of links comprises a plurality of neighboring pairs of slots. The system and method may include identifying a first usage status and a second usage status, calculating a utilization entropy value based at least on the difference between the first and second usage status, iteratively calculating a set of utilization entropy values for a portion of the network, and calculating an overall utilization entropy value for the portion of the network under analysis based at least on a statistical analysis of the set of utilization entropy values. | 12-27-2012 |
20130011138 | FLEXIBLE MULTI-BAND MULTI-TRAFFIC OPTICAL OFDM NETWORK - In accordance with some embodiments of the present disclosure a method for receiving and processing an optical orthogonal frequency-division multiplexed signal containing a plurality of traffics comprises receiving the optical orthogonal frequency-division multiplexed signal. The method further comprises down-converting the optical orthogonal frequency-division multiplexed signal into the electrical domain to obtain an electrical signal; filtering the electrical signal to obtain a first portion of the electrical signal containing a first of the plurality of traffics and preprocessing the first portion of the electrical signal in a first parallel preprocessor; filtering the electrical signal to obtain a second portion of the electrical signal containing a second of the plurality of traffics and preprocessing the second portion of the electrical signal in a second parallel preprocessor; and combining the preprocessed first and second portions of the electrical signal to yield a combined electrical signal and demodulating the combined electrical signal. | 01-10-2013 |
20130251368 | WAVELENGTH REASSIGNMENT IN OPTICAL NETWORKS - An optical network for reassigning a carrier wavelength of an optical signal may include first and second optical nodes. The first optical node may be configured to transmit an optical signal along an optical path. The first optical node may also be configured to tune a carrier wavelength of the optical signal from a first wavelength to a second wavelength, according to a continuous function, to reassign the carrier wavelength of the optical signal. The second optical node may be configured to receive the optical signal and may include a feedback loop configured to adjust a wavelength of a reference optical signal to approximate the carrier wavelength of the optical signal. | 09-26-2013 |
20130253896 | OPTIMIZING OPTICAL NETWORK SIMULATIONS - According to an aspect of an embodiment, a method of modeling an optical signal transmission path may include obtaining first transmission characteristics of an optical signal transmission path within an optical network based on a parameter of the optical network and randomly changing states of polarization of an optical signal within the optical signal transmission path. The method may also include obtaining second transmission characteristics of the optical signal transmission path based on the parameter and a first fixed state of polarization of the optical signal. The method may also include correlating the first transmission characteristics with the second transmission characteristics to obtain an effective state of polarization of the optical signal. A simulation of the optical signal transmission path based on the parameter and the effective state of polarization of the optical signal may produce transmission characteristics that may approximate the first transmission characteristics. | 09-26-2013 |
20130272702 | OPTICAL SIGNAL REGENERATION AND AMPLIFICATION OF M-PSK AND M-QAM MODULATION FORMATS USING RECONFIGURABLE WAVELENGTH SELECTIVE PROCESSORS AND PHASE-SENSITIVE AMPLIFIERS - A method for regenerating optical signal includes determining a source optical signal to be regenerated, adding a first pump optical signal and a second pump optical signal to the source optical signal to yield an intermediate optical signal, creating a first conjugate optical signal and a second conjugate optical signal from the intermediate optical signal, and performing degenerate phase-sensitive amplification utilizing the first conjugate optical signal, the second conjugate optical signal and the source optical signal to yield an output optical signal. The source optical signal is modulated with a multilevel modulation format. Each conjugate optical signal has a phase that is a conjugate of a multiple of the phase of the source optical signal. | 10-17-2013 |
20130272710 | DEFRAGMENTATION OF OPTICAL NETWORKS - According to an aspect of an embodiment, a method of spectrum defragmentation in an optical network may include assigning an optical signal within an optical network to a first frequency slot that spans a first portion of an optical spectrum of the optical network. The method may also include constructing a frequency slot dependency map based on the assignation of the optical signal to the frequency slot. The method may also include reassigning, as a result of an optical signal departure event, the optical signal to a second frequency slot based on the frequency slot dependency map. The second frequency slot may span a second portion of the optical spectrum of the optical network. | 10-17-2013 |
20140023362 | POLARIZATION DEPENDENT LOSS COMPENSATION - An apparatus including a polarization controller is described. The polarizer controller is communicatively coupled via a feedback loop to an evaluation module located near an optical receiver. The evaluation module is configured to measure polarization dependent loss (PDL) of an optical signal received at the optical receiver. The polarization controller is configured to receive feedback control data regarding the PDL from the evaluation module. Additionally, the polarization controller is configured to modify a state of polarization of the optical signal at an optical transmitter, which is communicatively coupled to the optical receiver, based on the feedback control data. | 01-23-2014 |
20140079390 | IN-BAND SUPERVISORY DATA MODULATION USING COMPLEMENTARY POWER MODULATION - According to an aspect of an embodiment, a method of modulating supervisory data onto an optical signal includes increasing a first power level of a first polarization component of an optical signal based on supervisory data. The method further includes decreasing a second power level of a second polarization component of the optical signal based on the supervisory data. The decrease in the second power level is substantially the same as the increase in the first power level such that a total power of the optical signal is substantially constant. | 03-20-2014 |
20140079391 | IN-BAND SUPERVISORY DATA MODULATION - According to an aspect of an embodiment, a method of modulating supervisory data onto an optical signal includes receiving supervisory data and adjusting a characteristic of a carrier of the optical signal for at least one of a first polarization component of the optical signal and a second polarization component of the optical signal based on the received supervisory data. The characteristic may be adjusted such that there is a relative difference between the characteristic for the first polarization component and the second polarization component. The relative difference of the characteristic between the first polarization component and the second polarization component may indicate the supervisory data. Alternately, the characteristic may be adjusted such that there is a change in a polarization orientation of the carrier on a Poincaré sphere that indicates the supervisory data. | 03-20-2014 |
20140099102 | SYSTEMS AND METHODS FOR STATISTICAL SHARING IN OPTICAL COMMUNICATIONS NETWORKS - A method of statistical sharing in an optical communications network is disclosed. The method includes identifying a peak transmission rate and a base transmission rate for each of a plurality of client interface cards of an optical node. | 04-10-2014 |
20140119743 | OPTICAL QPSK SIGNAL REGENERATION AND AMPLIFICATION - A method for regenerating and amplifying optical signals includes determining a source optical signal, adding a first pump optical signal and a second pump optical signal to the source optical signal to yield an intermediate optical signal, duplicating the intermediate optical signal to yield a first duplicate signal and a second duplicate signal, phase-shifting the first duplicate signal, passing the phase-shifted first duplicate signal and the second duplicate signal bi-directionally through a nonlinear optical element, and performing degenerate phase-sensitive amplification on the phase-shifted first duplicate signal and the second duplicate signal. | 05-01-2014 |
20140233965 | System and Method for Monitoring and Control of an Optical Modulator for an M-QAM Transmitter - A system includes an optical power meter operable to generate an optical power signal corresponding to the optical power of a received output signal generated by an optical IQ-modulator. The system further includes a processor operable to receive the optical power signal and determine, based on a minimization algorithm and the received optical power signal, a first bias voltage to be applied to a first sub-modulator of the optical IQ-modulator and a second bias voltage to be applied to a second sub-modulator of the optical IQ-modulator. The system may also include a peak power meter operable to generate a peak power signal corresponding to the peak power of the received output signal generated by the optical IQ-modulator, wherein the processor is further operable to determine, based on a minimization algorithm and the received peak power signal, a third bias voltage to be applied to a phase shift component of the optical IQ-modulator. | 08-21-2014 |
20140363164 | MITIGATION OF POLARIZATION DEPENDENT LOSS IN OPTICAL MULTI-CARRIER/SUPER-CHANNEL TRANSMISSION - Methods and systems for mitigating effects of polarization dependent loss (PDL) in an optical network transmitting a multi-carrier optical signal comprising a plurality of subcarriers may involve assigning and modifying a state of polarization to each subcarrier prior to transmission. An assigned state of polarization for each subcarrier may be modified for the subcarrier in the digital domain and/or the optical domain. Various specific assignment methods may be used, including individual subcarrier assignment, subcarrier set assignment, arbitrary subcarrier group assignment, random assignment, and/or combinations thereof. The assigned states of polarization may be selected based on a resulting minimum PDL-induced peak-to-peak power variation over a sum of the subcarriers for all orientations of a principal axis of PDL. | 12-11-2014 |
20140369679 | ASYMMETRIC COMPENSATION OF POLARIZATION DEPENDENT LOSS IN DUAL-POLARIZATION OPTICAL SYSTEMS - Methods and systems for asymmetrically compensating degradation of an optical signal-to-noise ratio (OSNR) induced by polarization dependent loss (PDL) in dual-polarization optical system include using an OSNR compensator. The OSNR compensator may separate the dual-polarization components and determine which component has degraded OSNR. The degraded component may be OSNR compensated using a phase-sensitive amplifier and/or a regenerator with a phase-sensitive amplifier. | 12-18-2014 |
20140376907 | MITIGATION OF OPTICAL SIGNAL TO NOISE RATIO DEGRADATION ARISING FROM POLARIZATION DEPENDENT LOSS - Methods and systems for mitigating degradation of an optical signal-to-noise ratio (OSNR) induced by polarization dependent loss (PDL) in an optical network include determining an increase in power (ΔP) corresponding to a PDL-induced decrease in OSNR for a given channel being transmitted over an optical signal transmission path. The increase in power (ΔP) may be adjusted for at least some of the network nodes in the optical signal transmission path. At certain network nodes, the increase in power (ΔP) may be realized with a combination of attenuation and gain. | 12-25-2014 |
20140376908 | SYSTEM AND METHOD FOR MONITORING A DUAL-POLARIZATION SIGNAL USING AN IN-BAND SUPERVISORY SIGNAL - Systems and method for monitoring an optical power of a dual-polarization signal are disclosed. The systems and methods may include measuring a first parameter set associated with a supervisory signal, the supervisory signal being communicated in-band with the dual-polarization signal; calculating a second parameter set from the first parameter set; calculating an intensity value from the second parameter set, the intensity value associated with one of the polarization states of the dual-polarization signal; and estimating a signal power associated with the supervisory signal from the intensity value. | 12-25-2014 |