Abstract: 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.

Abstract: A method and system to economically monitor an optical OOK signal that can detect perceptible changes in signal quality and identify the type of optical impairment causing the change. The invention requires a new and novel combination of known techniques to create an eye diagram of the transmitted pulse in a wavelength division multiplexing systems and then removing the noise from the eye diagram. Economy of operation is achieve by using asynchronous sampling techniques for generating the eye diagram. The resulting “cleaner” eye diagram is then analyzed to identify any changes in performance. In the preferred embodiment, the analysis is conducted on histograms generated from eye diagram, the histograms are computed at a number of points across the optical signal pulse period.

Abstract: An optical noise monitoring method and monitor, the monitor comprising an optical transmitter for receiving at least a portion of an optical signal, a device arranged to extract a reflected optical signal comprising a portion of the optical signal back-reflected by stimulated Brillouin scattering in the optical transmitter, and a photodetector for receiving the reflected optical signal. The optical transmitter can scatter the optical signal by stimulated Brillouin scattering.

Abstract: A level transition determination circuit includes a multi-phase clock generator, an oversampling unit, and a state detection circuit. The multi-phase clock generator is used for receiving an input clock signal and generating S×N clock signals, in which S and N are integers. Each clock signal is synchronized to the input clock signal and has a different delay time. The oversampling unit is used for performing N-times oversampling on M bit periods of the serial input data according to the clock signals, so as to generate M×N sampled values in parallel during the M bit periods. The state detection circuit is used for receiving (M×N)+1 sampled values and generating N detection signals by detecting level transitions between adjacent sampled values of the (M×N)+1 sampled values and the level transition results.

Abstract: A WDM optical transmission system includes a plurality of optical nodes optically coupled by a transmission line, a processor that is operative to calculate an amount of adjustment of a reception level capable of increasing an optical signal-to-noise ratio for each channel of the WDM light reaching the optical node positioned at a receiving end of the unit section based on information on amplification operation of the WDM light in at least one optical-amplification repeating node disposed on the optical transmission line in the unit section, and to adjust a power level corresponding to each channel of the WDM light transmitted on the transmission line from the optical node positioned at a transmission end of the unit section in accordance with a calculation result of the calculation.

Abstract: A method and apparatus for establishing a terahertz link using a multi-element lens array that comprises a plurality of active beam steering device are disclosed. For example, the method receives detected terahertz signals from one or more detectors, where an active beam steering device is deployed with each of the one or more detectors, and determines, for each of the detected signals, if the detected signal is out of focus from a focus point. The method applies a corrective signal to each active beam steering device that corresponds to a detected terahertz signal that is out of focus from the focus point, wherein the corrective signal causes the detected signal to be redirected, and measures a signal-to-noise ratio of the detected signals. The method then establishes the terahertz link via at least one of the detected terahertz signals with a highest signal-to-noise ratio.

Abstract: A method and memory medium in a wavelength division multiplexing (WDM) network that communicates multiplexed signals representing a plurality of communication channels to determine received signal quality are disclosed. Generally, the signals format the plurality of communication channels to impart a distinctive noise profile in time or frequency for each channel; and collectively process the channels at a digital signal processing device to measure the signal-to-noise ratio.

Abstract: There is provided a method for determining a noise parameter characterizing an optical Signal-Under-Test (SUT) having a signal contribution, an Amplified Spontaneous Emission (ASE) noise contribution and a non-ASE optical noise contribution, such as a carrier-leakage contribution or a depolarized-signal contribution, within an optical-signal bandwidth. The method comprises acquiring optical spectrum trace(s) of the SUT, discriminating at least the non-ASE optical noise contribution from the ASE-noise contribution using the optical spectrum trace(s) and/or a trace obtained from the optical spectrum trace(s); and determining the noise parameter using discriminated non-ASE optical noise contribution and/or the discriminated ASE-noise contribution.

Abstract: A method includes monitoring, by a transceiver, a first wavelength corresponding to a transmitted optical signal. The method includes monitoring a second wavelength corresponding to a received optical signal. The method also includes determining whether the first wavelength is identifiably different than the second wavelength. The method includes maintaining a separation between the first and second wavelengths if the first and second wavelengths are identifiably different. The first and second wavelengths are separated if the first and second wavelengths are not identifiably different. The method further includes maintaining the separation between the first and second wavelengths following separation of the first and second wavelengths.

Abstract: An optical signal-to-noise ratio monitor includes a demodulator comprising an input that receives at least a portion of a phase modulated optical signal. The monitor also includes a delay interferometer with a periodic phase control that sweeps a differential delay of one arm of the interferometer through a plurality of differential optical phase shifts. The demodulator converts phase modulated optical signals to intensity modulated optical signals. A tunable optical filter continuously scans a transmission wavelength over a desired wavelength range in a time that allows more than one wavelength to be transmitted through an output of the tunable filter for each of the plurality of differential optical phase shifts. An optical detector detects the filtered optical signal and generates a corresponding electrical demodulation signal at an output. A processor determines an optical signal-to-noise ratio for the more than one wavelength of the optical signal.

Abstract: A wavelength division multiplexing (WDM) transmission system for transmitting a wavelength division multiplexed signal light from a sender transmission apparatus to a receiver transmission apparatus is provided. The system comprises a computing unit that subtracts from a first optical signal noise ratio (OSNR) of the signal light measured by the receiver transmission apparatus a second OSNR ascribed to a sideband of the signal light measured by the sender transmission apparatus so as to compute a corrected OSNR of an amplified spontaneous emission (ASE) noise light with a reduction of an effect of the sideband.

Abstract: Various embodiments of a method and device for dark current cancellation for optical power monitoring in optical transceivers are presented. In one aspect, a device includes a photosensitive module and a processing module coupled to the photosensitive module. The photosensitive module is configured to detect an optical signal and generate a first signal responsive to detecting the optical signal. The processing module is configured to determine a value of a second signal that is related to noise and determine a value of a third signal that is related to a difference between a value of the first signal and the value of the second signal.

Abstract: In order to solve a problem of achieving distortion compensation with high accuracy, a digital filter device includes a first distortion compensation filter unit for conducting distortion compensation of first waveform distortion included in an inputted signal through digital signal processing, a first filter coefficient setting unit for setting a filter coefficient of the first distortion compensation filter unit, a second distortion compensation filter unit for compensating second waveform distortion included in a signal outputted from the first distortion compensation filter unit, and a second filter coefficient setting unit for setting a filter coefficient of the second distortion compensation filter unit based on the filter coefficient set by the first filter coefficient setting unit.

Abstract: Method and apparatus for optimizing a decision threshold of an optical receiver is used to solve a problem of affecting system stability and reliability. The method comprises: determining a maximum value and a minimum value of an adjustment range of the decision threshold, and determining an adjustment step of the decision threshold (10); adjusting a decision threshold value within the adjustment range of the decision threshold, and separately detecting pre-FEC BERs corresponding to different decision threshold values (11); and searching for a minimum value in the detected pre-FEC BERs, a decision threshold value corresponding to the minimum value being an optimal decision threshold value (12). The apparatus comprises a decision threshold adjusting unit, a pre-FEC BER detecting unit, a decision threshold control unit and an optimal decision threshold determining unit.

Abstract: Increasing data rates in next-generation optical networks requires a change in the type of optical modulation used to encode optical signals carried by the optical networks. Different types of optical modulation incur different optical impairments, which may degrade the fidelity of the optical signals by reducing the optical signal-to-noise ratio (OSNR). A method or corresponding apparatus in an example embodiment of the present invention provides a planning tool for deploying an optical network in a manner based on the optical modulation that reduces the cost and complexity of the deployed network. In one embodiment, the disclosed planning tool may adjust a model of the optical network to be deployed by changing the topology and/or the number and/or type of optical network elements in response to optical impairments for a given optical modulation.

Abstract: A method for monitoring wavelength-division multiplexed (WDM) signal for detecting signal drift of objective signals, including generation of one or more objective signals and a guard signal. The guard signal has a wavelength that is within a range defined by a guard channel. The first and second objective signals and the guard signal are wavelength-division multiplexed to generate a wavelength-division multiplexed signal. The first objective signal, the second objective signal, and the guard signal are assigned to a first multiplexed objective channel, a second multiplexed objective channel, and a multiplexed guard channel, respectively. The wavelength-division multiplexed signal is received by a monitor and then the error rate of the multiplexed guard channel is determined.

Abstract: An optical communication system has a receiver that includes a plurality of photon counting sensors that each receive photons and generate pulses based on the received photons, and an electronic circuit that aggregates the number of pulses from the plurality of photon counting sensors into a merged pulse count. A demodulator samples the merged pulse count at predetermined time intervals to determine a number of photons received by the plurality of photon counting sensors during different sampling time intervals.

Abstract: The path selection and wavelength assignment to a selected path are performed by mapping the wavelength reach to the demand distribution (agile reach) resulting in a 50-60% increase in the network reach. The network reach is further increased (about 2.2 times) when on-line measured performance data are used for path selection and wavelength assignment. The connections may be engineered/upgraded individually, by optimizing the parameters of the entire path or of a regenerator section of the respective path. The upgrades include changing the wavelength, adjusting the parameters of the regenerator section, controlling the launch powers, mapping a certain transmitter and/or receiver to the respective wavelength, selecting the wavelengths on a certain link so as to reduce cross-talk, increasing wavelength spacing, etc.

Abstract: A method and apparatus for establishing a terahertz link using a multi-element lens array that comprises a liquid lens are disclosed. For example, the method receives detected terahertz signals from one or more detectors, where a liquid lens is deployed with each of the one or more detectors. The method determines, for each of the detected signals, if the detected signal is out of focus, and applies a corrective voltage to each liquid lens that corresponds to a detected terahertz signal that is out of focus, wherein the corrective voltage adjusts a focus of the detected signal. The method measures a signal-to-noise ratio of the detected signals, and establishing a terahertz link via at least one of the detected terahertz signals with a highest signal-to-noise ratio.

Abstract: An apparatus includes a first estimator that estimates a signal quality based on an error correction number of an electrical signal obtained by photoelectrically converting a received optical signal; a second estimator that estimates a signal quality from which the influence of nonlinear effects is removed based on signals upstream and downstream of an identification calculator identifying the electrical signal; and a calculator that calculates the difference between the signal qualities estimated by the first and second estimators to calculate the amount of nonlinear effects.

Abstract: A fiber optic system includes a transmitter configured to utilize a plurality of modulation formats and a receiver communicatively coupled to the transmitter and configured to utilize a plurality of modulation formats. The transmitter and the receiver are cooperatively configured to set a modulation format of the plurality of modulation formats based upon optical signal-to-noise ratio associated therewith. A flexible bandwidth adaptation method includes monitoring at least one aspect of an optical link at a network element, responsive to the at least one aspect, computing a new modulation scheme for the optical link, and, if a solution is found for the new modulation scheme, changing to the new modulation format.

Abstract: A receiver for a communications link includes a receiver module and a host receiver. These two components can be tested independently. In one embodiment, the receiver module is characterized with respect to noise and distortion. The noise performance can be determined by comparing input and output signals of the receiver module, to determine the relative noise of the receiver module. The distortion performance can be determined by comparing the distortion of input and output signals of the receiver module, using a reference host receiver that includes an equalizer. The host receiver can be tested by using a reference receiver module.

Abstract: A binary intensity-modulated light signal to be monitored is split into three signal beams. The first and third beams are converted into electric signals. Frequencies of the first electric signal corresponding to a bit rate pass a filter bank. The intensity of the filtered signal is detected by an RF intensity detector. A delaying interferometer makes the second beam interfere with a light signal obtained by delaying the second beam by a predetermined delay time. One of the resulting interference signals is converted into an electric signal. The intensities of the amplified signal are detected by another RF intensity detector. The third electric signal is smoothed by the filter bank, and its average intensity is detected by a power detector. The intensities of the detected, amplified signals are found relative to the detected average intensity to determine wavelength dispersion and optical SNR or the tendency of their changes.

Abstract: A method and apparatus for monitoring and controlling an optical node 100. The optical node 100 including one or more optical components 120, 121 or 122 connected by optical fibre carrying an optical signal 102. The optical signal 102 including a plurality of optical channels. A set of measurement sequences is determined, each measurement sequence defining a set of optical channels from the plurality of optical channels and a measuring sequence for measuring an optical property of the set of optical channels. A measurement sequence is selected from the set of measurement sequences based on the operating conditions of the optical node 100. The optical properties of the set of optical channels of the selected measurement sequence are measured. The measured optical properties are analysed to determine whether one or more optical components 120, 121 or 122 are causing the optical node 100 to operate outside the tolerance of a defined set of operating conditions.

Abstract: There is provided a method for determining the in-band noise in agile multichannel Dense Wavelength Division Multiplexing (DWDM) optical systems, where the interchannel noise is not representative of the in-band noise in the optical channel. The method relies on the analysis of two observations of the same input optical signal. In the two observations, the linear relationship between the optical signal contribution and the optical noise contribution (e.g. the observed OSNR) is different, which allows the discrimination of the signal and noise contributions in the input optical signal. In a first approach, the two observations are provided by polarization analysis of the input optical signal. In a second, the input optical signal is obtained using two different integration widths.

Abstract: Increasing data rates in next-generation optical networks requires a change in the type of optical modulation used to encode optical signals carried by the optical networks. Different types of optical modulation incur different optical impairments, which may degrade the fidelity of the optical signals by reducing the optical signal-to-noise ratio (OSNR). A method or corresponding apparatus in an example embodiment of the present invention provides a planning tool for deploying an optical network in a manner based on the optical modulation that reduces the cost and complexity of the deployed network. In one embodiment, the disclosed planning tool may adjust a model of the optical network to be deployed by changing the topology and/or the number and/or type of optical network elements in response to optical impairments for a given optical modulation.

Abstract: A method and apparatus for performing a path based quality check for a specified bit rate in a wavelength division multiplexing optical network is described. According to one embodiment of the invention, a method selects from a database one of the available paths as a currently selected path. The database stores a representation of the available paths from an access node of the optical network to other access nodes of the optical network. The method further determines a cumulative noise, cumulative chromatic dispersion, and a maximum allowable chromatic dispersion for the currently selected path. In addition, the method determines whether the currently selected path passes the path based quality check based on whether the cumulative noise is less than the maximum allowable noise at a specific bit rate and whether the chromatic dispersion is less than the maximum allowable chromatic dispersion at the specified bit rate.

Abstract: A method of configuring a path between an ingress node and an egress node in an optical communications network, the path comprising a first hop and a subsequent hop. The method includes: a) selecting a candidate hop for the first hop of the path; b) obtaining a value of a signal feasibility parameter for the candidate hop; c) determining whether said value lies within an acceptable value range and if one is, accepting said candidate hop for the first hop of the path, and if one is not, repeating steps a. to c.; d) selecting a candidate hop for the subsequent hop of path; e) obtaining a value of a signal feasibility parameter for a combined path comprising the first hop and the candidate hop for the subsequent hop of the path; f) determining whether said value lies within an acceptable value range, if one is, acceptable value range accepting said candidate hop for the subsequent hop of the path, and if one is not, repeating steps d. and e.

Abstract: Having a fast method to perform impairment evaluation is useful for many networks. A method or corresponding apparatus according to an example embodiment of the present invention maintains a traffic engineering database of values representing characteristics of links in the network through storage of integer values representing advertised optical signal capabilities of links between the multiple optical nodes. The example embodiment determines a path through the network for optical wavelengths to be supported by the links represented in the database as a function of evaluating optical signal characteristics at each link along a possible path using the advertised optical signal capabilities and provides a selected path meeting an acceptable integrity of the optical wavelengths to a path establishment module to establish the path through the optical network. Example embodiments significantly reduce computational complexity associated with impairment evaluation and path selection in an optical network.

Abstract: A method of controlling a multiple sub-carrier optical channel of an optical communications system. The multiple sub-carrier optical channel includes at least two sub-carriers modulated with respective sub-channel data streams within a spectral range allocated to a single optical channel of the optical communications system. A transmitter modem of the optical communications system applies a respective dither signal to each sub-carrier. A receiver modem of the optical communications system detects a respective quality metric of each sub-carrier. A respective optimum power level of each sub-carrier is estimated based on the applied dither signals and the detected quality metrics. A respective power level of each sub-carrier is then adjusted in accordance with the estimated respective optimum power level of each sub-carrier.

Abstract: An optical amplifying device includes an optical amplification medium configured to be excited by excitation light and amplify signal light, a light loss detector configured to detect a light loss of an optical component optically connected to the optical amplification medium in the amplifying device, and a noise figure deterioration detector configured to detect, based on the light loss detected by the light loss detector, deterioration of a noise figure of the optical amplification medium.

Abstract: An attenuation amount corresponding to each wavelength at OADM node is optimized according to a calculation result in a network management system (NMS), so that an optical signal level diagram according to traffic volume variations is set, the level diagram allows each of optical signal quality indexes at terminal nodes for all wavelengths to be maintained at a required threshold value or more, and allows an optical signal quality index of a specific wavelength to be improved. Then, an FEC circuit in an optical receiver corresponding to the specific wavelength is turned OFF or the error correction ability is lowered, whereby power consumption of an overall optical network is efficiently reduced.

Abstract: In one example embodiment, an optoelectronic module includes an optical receiver and a post-amplifier. The optical receiver is configured to receive an optical signal and generate an electrical data signal corresponding to the optical signal. The post-amplifier is electrically connected to the optical receiver and is configured to amplify the electrical data signal. The optoelectronic module further includes means for quantifying a quality of the optical signal from which the amplified electrical data signal is derived.

Abstract: An optical reception device is provided. The optical reception device includes a filtering unit that receives input light of predetermined power, filters the input light by use of filter characteristics where the degree of attenuation of the power of an optical signal of predetermined frequency is lower than the degree of attenuation of the power of an optical signal of another frequency, and supplies an output light; and a determining unit that compares a value relevant to the power of the output light supplied by the filtering unit, with a threshold, and determines whether the input light contains signal light.

Abstract: An optical packet switching system includes a plurality of network elements for transmitting and receiving optical packet signals. Each network element includes an optical signal-to-noise ratio (OSNR) acquiring unit for acquiring the OSNR of each optical packet signal, an average value calculating unit for calculating the average value of the OSNRs of optical packet signals received within a predetermined time duration for each of the plurality of source network elements, and a difference information transmitter for calculating the difference between the calculated average value of the OSNRs and a target value of the OSNRs and then transmitting the difference to a network element corresponding to the difference. A source network element that has received the difference information adjusts the characteristics of an optical packet signal to be transmitted in a manner such that the difference is reduced.

Abstract: A method and apparatus for performing a path based quality check for a specified bit rate in a wavelength division multiplexing optical network is described. According to one embodiment of the invention, a method selects from a database one of the available paths as a currently selected path. The database stores a representation of the available paths from an access node of the optical network to other access nodes of the optical network. The method further determines a cumulative noise, cumulative chromatic dispersion, and a maximum allowable chromatic dispersion for the currently selected path. In addition, the method determines whether the currently selected path passes the path based quality check based on whether the cumulative noise is less than the maximum allowable noise at a specific bit rate and whether the chromatic dispersion is less than the maximum allowable chromatic dispersion at the specified bit rate.

Abstract: A method for determining an optical signal-to-noise ratio penalty as a measure for a quality of an optical signal transmitted via an optical link between a source optical node and a destination optical node in an optical network, the method includes collecting information of the optical link; determining a configuration parameter Pconf of the optical link based on the information of the optical link; adjusting the configuration parameter Pconf to an adjusted configuration parameter P?conf according to linear impairments in the optical link; and determining the optical signal-to-noise ratio penalty based on a non-linear function of the adjusted configuration parameter P?conf, the non-linear function accounting for non-linear impairments in the optical link.

Abstract: Changes in a signal are detected. The signal is repeatedly sampled in a synchronous manner during a predetermined interval to generate a captured eye diagram. At least one of a positive differential eye diagram or a negative differential eye diagram is generated from the captured eye diagram and a baseline eye diagram. The at least one positive or negative differential eye diagram is analyzed to determine whether a change in signal conditions is present.

Abstract: A method comprises: acquiring, for a number nSOP of varied State-Of-Polarization analysis conditions of the input optical signal, nSOP polarization-analyzed optical spectrum traces; mathematically discriminating said signal contribution from said noise contribution within said optical signal bandwidth using said polarization-analyzed optical spectrum traces, said mathematically discriminating comprising: obtaining a differential polarization response that is related to the optical spectrum of said signal contribution by a constant of proportionality; estimating the constant of proportionality of a differential polarization response to the optical spectrum of said signal contribution; estimating the optical spectrum of said noise contribution from said input optical signal, within said optical signal bandwidth using said constant of proportionality and said differential polarization response; and determining said in-band noise parameter on said input optical signal from the mathematically discriminated noise c

Abstract: There is provided a method for determining the in-band noise in agile multichannel Dense Wavelength Division Multiplexing (DWDM) optical systems, where the interchannel noise is not representative of the in-band noise in the optical channel. The method relies on the analysis of two observations of the same input optical signal. In the two observations, the linear relationship between the optical signal contribution and the optical noise contribution (i.e. the observed OSNR) is different, which allows the discrimination of the signal and noise contributions in the input optical signal. In a first approach, the two observations are provided by polarization analysis of the input optical signal. In a second, the input optical signal is obtained using two different integration widths.

Abstract: An optical packet switching apparatus includes an optical switch unit for switching the route of an optical packet signal, an OSNR acquiring unit for obtaining the information on the optical-to-noise ratio (OSNR) of the optical packet signal, and a regenerative relay unit for regenerating and relaying the optical packet. When the OSNR of the optical packet signal is less than a predetermined reference value, the optical switch unit outputs the optical packet signal to the regenerative relay unit. The regenerative relay unit sends back the regenerated optical packet to a route through which the optical packet is supposed to be sent out.

Abstract: A network comprises nodes connected by optical sections. The nodes support a plurality of traffic types. A candidate optical path having a first traffic type is selected as a routing for at least part of the connection on the basis of at least one routing metric. Pre-computed parameters are retrieved for the optical sections of the candidate optical path. The pre-computed parameters are indicative of quality of transmission along the optical section for the first traffic type. A quality of transmission is determined along the candidate optical path using the retrieved parameters. The pre-computed parameters for each of the optical sections can be used at a network planning tool and then exported to a network management system or a path computation entity at a node for creating a validation module for use in validating connections across the optical transmission network.

Abstract: A WDM transmission apparatus to receive or relay WDM light in a WDM transmission system, includes a measuring unit configured to measure an optical level of each channel transmitted by the WDM light; an adjusting unit configured to adjust a resolution of the measuring unit; and a processing unit configured to obtain, for each channel, optical level information which represents an optical level respectively measured with a resolution corresponding to a bit rate of a transmission signal of each channel.

Abstract: An optical packet switching system includes an optical packet generator for generating an optical packet signal, an optical packet switching unit, provided with an optical switch, for switching the route of an inputted optical packet signal by controlling on/off of the optical switch, and an optical signal-to-noise ratio measuring unit for measuring the optical signal-to-noise ratio of the optical packet signal outputted from the optical packet switching unit. When switching the route of the optical packet signal, the optical packet switching unit outputs an optical packet signal with optical noise by keeping the optical switch on longer than the time width of the packet signal. The optical signal-to-noise ratio measuring unit measures the optical signal power and the optical noise power, respectively, in the optical packet signal with optical noise and measures the optical signal-to-noise ratio by calculating the ratio between the optical signal power and the optical noise power.

Abstract: A method for estimating optical power in an optical channel includes determining a tunable filter full-width, FWF, by measuring a response of the tunable filter to a known signal and mapping the response to frequency. A portion of an optical channel is coupled to an input of the tunable optical filter. A peak power response, PR, and a full width tunable filter response, FWR, to the optical channel are determined by measuring a response of the tunable filter to the optical channel and mapping the response to frequency. A signal power, PS, is then calculated from the peak power response, PR, and a ratio of the full width tunable filter response, FWR, to the tunable filter full-width, FWF.

Abstract: 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.

Abstract: An optical noise signal is added to an optical data signal on the receiver side, and a signal quality of the data signal is determined. The magnitude of the added noise signal is varied, and a function of the signal quality of the data signal is determined in dependence on the added noise signal. Subsequently, a first straight line is approximated to the previously determined function for smaller values of the added noise signal, and a second straight line for larger values of the added noise signal. The optical signal-to-noise ratio is read from the intersecting point of the first straight line with the second straight line. Thus, the ASE present is derived from the controlled addition of additional ASEs, and the optical signal-to-noise ratio is determined. The process is particularly suited for DWDM systems because it works even with very narrow channel separations, or with narrowband optical filtration along the separation.

Abstract: In accordance with an embodiment of the present disclosure a method for adaptively spacing channels of an optical network comprises determining a first desired power level of a first channel of an optical network. The method further comprises determining a second desired power level of a second channel of the optical network, the second desired power level being less than the first desired power level. Additionally, the method comprises determining a first spectral space between the first channel and one or more channels neighboring the first channel based at least on the first desired power level. The method also comprises determining a second spectral space between the second channel and one or more channels neighboring the second channel based at least on the second desired power level, the second spectral space less than the first spectral space.

Abstract: A system and method is disclosed that allows for the monitoring, analyzing and reporting on performance, availability and quality of optical network paths. The correlation of PM parameter metrics to client connections, coupled with threshold-based alarm generation provides a proactive and predictive management, reporting and analyzing of the health and effectiveness of individual path connections to alert Operational Support (OS) staff and/or customers to signal degradation and impending Network Element (NE) failures. The system and method performs in real-time processing intervals required for alarm surveillance in a telecommunications network.

Abstract: An optical communication apparatus that includes multiple optically communicative components positioned optically in series. Some of the optically communicative components may be optical fiber segments of perhaps different types. The optical channel represented by the series of optically communicative components and approximates a transfer function of an optical channel of a longer optical fiber. Accordingly, rather than deal with a lengthy optical fiber, an apparatus having a shorter optical channel may be used instead. The construction of the optical communicative components may be calculating an input transfer function. The construction would include an ordering of discrete optically communicative components that, when placed optically in series, simulates an estimation of a particular transfer function. Testing may then occur by actually passing an optical signal through the series construction of optically communicative components, rather than through the longer optical fiber.