Abstract: A tunable dispersion compensation device includes a plurality of tunable dispersion compensators coupled in series, a controller configured to control an amount of chromatic dispersion to be set in each of the plurality of tunable dispersion compensators, and a table including a correspondence relationship between an amount of chromatic dispersion and a wavelength band, for each of the plurality of tunable dispersion compensators, wherein the controller decides an amount of chromatic dispersion to be set in each of the plurality of tunable dispersion compensators, based on a total amount of chromatic dispersion desired for the plurality of tunable dispersion compensators and the correspondence relationship included in the table so that a difference between bandwidths of a first tunable dispersion compensator having the widest wavelength band and a second tunable dispersion compensator having the narrowest wavelength band, among the plurality of tunable dispersion compensators, is within a given range.

Abstract: 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.

Abstract: 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.

Abstract: The chromatic dispersion of an optical component is measured with high accuracy using a simple set-up, which includes a pump light source, a probe light source, and a measuring means. Pump light having a wavelength ?pump and probe light having a wavelength ?probe is propagated through an optical component, with the wavelength ?probe being apart from the wavelength ?pump by a given frequency. The generation efficiency of the idler light with respect to the wavelength ?pump is calculated by measuring the power of idler light having a wavelength ?idler output from the optical component, and by seeking the pump light wavelength for making the generation efficiency a local extreme value, the chromatic dispersion of the optical component is calculated from the result of calculation of phase mismatch among the pump light wavelength having such wavelength as sought, the corresponding probe light wavelength, and the corresponding the idler light wavelength.

Abstract: An OADM in a wavelength division multiplexing transmission system includes a wavelength selection switch that selects a predetermined wavelength from a multiple optical signal obtained by multiplexing a phase modulated signal and an intensity modulated signal and outputs the selected wavelength signal to a predetermined output port. The wavelength selection switch has a different delay for each wavelength of the multiple optical signal. For example, the wavelength selection switch includes a mirror array. Optical paths from the surfaces of mirrors arranged on the mirror array to the diffraction grating are different in the case of adjacent mirrors.

Abstract: According to the WDM optical transmission system, for optical signals of respective wavelength in a WDM light propagated through a transmission path, a spectrum component at a center wavelength of each optical signal and a spectrum component in the vicinity of the center wavelength thereof are selectively attenuated by a spectrum correction optical filter, so that the WDM light is transmitted in a state where intensity of sideband components in the spectrum of each optical signal is relatively increased. As a result, even if spectrum width of the optical signal of each wavelength is limited when the WDM light passes through the band-limiting device on the transmission path, degradation of transmission characteristics caused by the attenuation of sideband components is reduced.

Abstract: An arrangement is described for compensating intra-channel nonlinearities in an optical communications system which combines optical dispersion compensation with electronic pre-distortion (EPD). EPD with moderate lookup table size can effectively suppress intra-channel nonlinearities over optical transmission links incorporating optical dispersion compensation. The arrangement can be implemented for a variety of optical communications systems, including 10 Gb/s, 40 Gb/s and higher bit rate systems as well as single-channel and wavelength-division multiplexing (WDM) systems.

Abstract: A tunable dispersion compensator (TDC) is tuned from a first dispersion setpoint to a second dispersion setpoint while maintaining continuity of the dispersion. The dispersion tuning follows a pre-determined trajectory in the time domain, so that continuity of the optical dispersion across the channel optical bandwidth is maintained while minimizing all other TDC-induced optical impairments during a tuning period.

Abstract: A dispersion compensation device includes: an optical branching unit to branch an optical signal to be received; a first dispersion compensator to perform dispersion compensation on one part of the optical signal branched by the optical branching unit with a variable compensation amount; a second dispersion compensator to perform dispersion compensation on another part of the optical signal branched by the optical branching unit; a monitoring unit to monitor the communication quality of an output optical signal of the second dispersion compensator; and a controlling unit to determine the direction of variation in chromatic dispersion of the optical signal based on the direction of variation in communication quality monitored by the monitoring unit and control the compensation amount of the first dispersion compensator based on the result of the determination.

Abstract: A receiver includes wavelength demultiplexer for demultiplexing a received WDM light into light signals at respective central frequencies thereof, delay interferometer for converting a light signal output from wavelength demultiplexer into an intensity signal, and light detector for converting an output signal from delay interferometer into an electric signal. The interval between interferential frequencies of delay interferometer is 2/(2n+1) times the interval between the central frequencies of the WDM light. Logic inverting circuit outputs the output signal from the light detector while non-inverting or inverting the logic level thereof depending on the received central frequency.

Abstract: A WDM optical transmission system includes a plurality of optical transmission devices, each of which include a first memory that stores a first control program that controls a dispersion compensation amount in a host device; a processor to execute the first control program; a notification frame transmission circuit that transmits an information indicating a setting value of the dispersion compensation amount and a detection result corresponding to the setting value to another device; a third memory that stores a second control program that calculates a control value of the dispersion compensation amount in the another device; and a control frame transmission circuit that transmits the control value to the another device, wherein the processor executes the second control program when a problem occurs in the another device, and controls the dispersion compensation amount in the host device when a problem occurs in the host device.

Abstract: An optical communication apparatus includes a receiver configured to receive an optical signal transmitted from an optical transmitting apparatus; a detector configured to detect a predetermined pattern signal included in the optical signal; a calculator configured to calculate, based on a waveform of the predetermined pattern signal, an amount of dispersion of the predetermined pattern signal; and a compensator configured to compensate for dispersion according to the amount of dispersion.

Abstract: A distortion compensation system and method may be used to compensate for data pattern dependent signal distortion in a signal received in a coherent optical signal receiver. In general, the distortion compensation system and method compares a received signal field with stored distorted signal waveforms associated with known data patterns and selects a compensation value associated with the distorted signal waveform that corresponds most closely with the received signal field. The distortion compensation system and method compensates the received signal using the selected compensation value and thus mitigates the effects of data pattern dependent signal distortion.

Abstract: A dispersion compensation device includes a variable dispersion compensator configured to subject an input optical signal to dispersion compensation, an optical receiver configured to convert an optical signal subjected to dispersion compensation into an electrical signal, recover a clock signal and a received data signal from the electrical signal, and output clock lock information indicating whether the clock signal is locked to the electrical signal, a signal processor configured to output bit error rate information on the received data signal, and a controller configured to variably control a dispersion compensation value of the variable dispersion compensator based on the bit error rate information and the clock lock information.

Abstract: Where add optical signals have k different bit rates, an add controller is connected to k (<N) of N input ports and sends the add optical signals to the k input ports to perform add control. A drop controller is connected to m (<M) of M output ports and performs drop control on optical signals from the m output ports. The k input ports of an N×M wavelength selective switch and the add controller are connected by k links (L1 to Lk) which have introduced therein dispersion compensators for compensating chromatic dispersions of the add optical signals with the respective bit rates. The add controller selects a link through which an add optical signal is to be passed for dispersion compensation, and sends the signal to the N×M wavelength selective switch via the selected link.

Abstract: A dispersion compensation method and a dispersion compensation device in an optical communication system are provided. The method mainly includes the following steps. A dispersion compensation value transmitted through a working path at a second wavelength is received through a non-working path at a first wavelength in an optical communication system. The non-working path at the first wavelength and the working path at the second wavelength use the same service channel. Dispersion in the non-working path at the first wavelength is compensated according to the dispersion compensation value. Therefore, no matter the working path is a main path or a backup path, the dispersion compensation value on the non-working path can be accurately regulated in time, such that the dispersion of the working path reaches an optimal status each time after the protection switching occurs to the service, thereby ensuring the fast switching of the service.

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.

Abstract: The pulse light source according to the present invention comprises: a seed pulse generator 1 for outputting an input pulse 10 as a seed pulse; a pulse amplifier 2; and a dispersion compensator 3 for dispersion compensating a light pulse output from the pulse amplifier 2. Moreover, the pulse amplifier 2 comprises a normal dispersion medium (DCF 4) and an amplification medium (EDF 5) that are multistage-connected alternately, for changing the input pulse 10 to a light pulse having a linear chirp and outputting the light pulse. Furthermore, an absolute value of the dispersion of the DCF 4 becomes to be larger than the absolute value of the dispersion of the EDF 5.

Abstract: 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.

Abstract: A method for determining a value of chromatic dispersion compensation in an optical network including a plurality of nodes connected by at least one transmission line, the plurality of nodes including a plurality of dispersion compensators, the optical network including a plurality of wavelength paths between the optional nodes, the method includes determining a compensation value of the dispersion compensators in the optical network by the computer, the compensation value selecting that an error between the object value of the residual chromatic dispersion in accordance with of the first end node of the first path and the permissible value of the residual chromatic dispersion of the first end node of the first path is least, and the value of the residual chromatic dispersion of the first end is in the permissible value of the residual chromatic dispersion of the second end node of the second path.

Abstract: There is provided an optical waveguide element comprises: a core of an optical waveguide; and a Bragg grating pattern that is provided on the core, wherein a pitch of the Bragg grating pattern takes a value from among three or more predetermined discrete values; the pitches that take the respective discrete values are present in a plurality of locations over an entire length of the optical waveguide respectively; and if a value from among all of the discrete values which has the highest distribution frequency is taken as M, and if the closest value to the M which is larger than the M is taken as A, and if the closest value to the M which is smaller than the M is taken as B, then a difference expressed as A?M is equal to a difference expressed as M?B.

Abstract: There is provided a planar optical waveguide element comprises a core of an optical waveguide; and first Bragg grating pattern and second Bragg grating pattern that are provided on the core, wherein the first Bragg grating pattern and the second Bragg grating pattern are mutually parallel along a propagation direction of guided light.

Abstract: In a network design apparatus, a full channel evaluator determines whether all wavelength channels for main signals can deliver the main signals of an existing optical network. When it is found that one or more wavelength channels cannot deliver main signals, a chromatic dispersion evaluator determines whether there are a specified number of wavelength channels that satisfy a specified chromatic dispersion condition. An optical signal-to-noise ratio (SNR) evaluator extracts a specified number of wavelength channels out of those satisfying the chromatic dispersion condition in descending order of optical SNRs thereof, and determines whether the extracted wavelength channels satisfy a specified optical SNR condition.

Abstract: 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.

Abstract: The present invention is directed towards systems and methods for adjusting intensity, wavelength and higher and lower frequency components of an optical signal. Photonic apparatus receives a first and a second optical signal. A waveguide provides an anomalous group velocity dispersion the first optical signal or the second optical signal and adjusts intensity or wavelength of the first optical signal or the second optical signal, in response to the anomalous group velocity dispersion. In some embodiments photonic apparatus receives an optical signal comprising a lower frequency component received an amount of time prior to a higher frequency component of the optical signal. A waveguide provides an anomalous group velocity dispersion for the optical signal and adjusts the amount of time between the higher frequency component and the lower frequency component in response to the anomalous group velocity dispersion.

Abstract: A signal detection method used in an optical receiver apparatus detects the variation of an optical input level from the presence or absence of a clock signal and appropriately controls a dispersion compensator, thereby enabling the presence or absence of an input signal to be correctly determined. The signal detection method includes: detecting the level of input light of an optical amplifier, storing the level of the detected input light, comparing the level of the stored previous input light with the level of current input light, detecting the level variation of the input light by the comparison to detect the state change of the presence or absence of an optical signal, performing a dispersion compensation on the input light, and extracting a clock from an optical input. When the level variation of the input light is detected, the presence or absence of the optical signal of the input light is determined from the presence or absence of the clock signal.

Abstract: 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.

Abstract: A polarization multiplexing optical receiver includes a polarization controller configured to control a polarization state of a polarization multiplexed optical signal; a polarization splitter configured to split the polarization multiplexed optical signal for which the polarization state is controlled by the polarization controller into a first polarization signal and a second polarization signal; a first detector configured to detect an optical power of the first polarization signal and output a first optical power signal representing the optical power of the first polarization signal; a second detector configured to detect an optical power of the second polarization signal and output a second optical power signal representing the optical power of the second polarization signal; and a controller configured to control the polarization controller on the basis of the first optical power signal and the second optical power signal.

Abstract: An apparatus for generating a dispersion compensation signal includes a splitting module for splitting a data signal to be transmitted into N channels of data signals; N pre-processing modules for adjusting in frequency domain the phases and amplitudes of the N channels of data signals and outputting N channels of pre-warped electrical signals; an optical carrier generating module for generating N channels of coherent optical carriers; N electro-optic modulators for modulating the N channels of coherent optical carriers based on the N channels of pre-warped electrical signals and generating N channels of pre-warped optical signals; an optical coupling module for coupling the N channels of pre-warped optical signals into a dispersion compensation optical signal. By pre-processing the data signals, the present disclosure may allow the use of existing devices to generate a dispersion compensation signal so that the bandwidth requirement set by prior art on the electrical device is reduced.

Abstract: 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.

Abstract: In an example embodiment, lightwave device for use in a dispersion compensator, includes a light coupler configured to direct light toward a grating structure. The light coupler includes a first strip including a first material and a second strip attached to the first strip. The second strip includes a second material, and the second material has an expansion coefficient different than the first material. The first and second strips form a deformable reflector. A thermoelectric unit is coupled to the light coupler and is configured to adjust a shape of the deformable reflector based on a temperature of the thermoelectric unit. A support member is connected to the light coupler and is configured to position the deformable reflector so to receive light for transmission to the grating structure. Another embodiment provides a dispersion compensator using the lightwave device.

Abstract: 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 polarization controller is operable based on the feedback signal to mitigate the polarization mode dispersion of the signal.

Abstract: Methods and apparatus are described for DWDM transport of CATV and digital signals over optical fiber in low-dispersion spectral regions. A method includes transporting a plurality of optical carriers of different wavelengths over an optical link using wavelength division multiplexing, the optical link including a plurality of optical segments. The plurality of optical channel center wavelengths defined by the plurality of optical carriers are clustered proximate an average value of a zero-dispersion wavelength of the optical link, or near either a) a low wavelength edge or b) a high wavelength edge of a range of zero-dispersion wavelengths of the optical link and a plurality of optical channel center frequencies defined by the plurality of optical channel center wavelengths are non-uniformly spaced apart.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Where add optical signals have k different bit rates, an add controller is connected to k (<N) of N input ports and sends the add optical signals to the k input ports to perform add control. A drop controller is connected to m (<M) of M output ports and performs drop control on optical signals from the m output ports. The k input ports of an N×M wavelength selective switch and the add controller are connected by k links (L1 to Lk) which have introduced therein dispersion compensators for compensating chromatic dispersions of the add optical signals with the respective bit rates. The add controller selects a link through which an add optical signal is to be passed for dispersion compensation, and sends the signal to the N×M wavelength selective switch via the selected link.

Abstract: A device and method for stabilizing the state of polarization of polarization multiplexed optical radiation including an identified channel is disclosed.

Abstract: 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.

Abstract: An aspect of the embodiments utilizes an optical transmission apparatus which includes a rough adjustment execution portion that monitors a bit error rate of an optical signal for set values of a dispersion compensator where the set values have been set less closely to each other within a dispersion compensation control range than when a wavelength dispersion value set in the dispersion compensator is determined, and carries out a rough adjustment to determine a comparison threshold value used to set the wavelength dispersion value based on the monitored bit error rate, and a fine adjustment execution portion that monitors the bit error rate for the dispersion compensator the set values have been set more closely to each other, and carries out an adjustment to determine a wavelength dispersion value corresponding to the midpoint between the two acquired bit error rates as the wavelength dispersion value of the dispersion compensator.

Abstract: Optical transmission equipment includes: a first optical amplifier to amplify an input optical signal; a second optical amplifier provided at an output side of the first optical amplifier; an optical module having a first relay port to receive an optical signal from the first optical amplifier, a second relay port to output an optical signal to the second optical amplifier, an optical device provided between the first relay port and the second relay port, and a first output port optically couplable to the optical device; and a second output port to output the optical signal amplified by the second optical amplifier.

Abstract: 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.

Abstract: In an optical network design apparatus, a constraint setter sets a first constraint that one of alternative values given beforehand is selected as the dispersion compensation amount of each node, sets a first margin value that assumes a nonnegative value, sets a second constraint that the first margin value is equal to or greater than the difference between the residual dispersion and the lower bound of an allowable range, sets a second margin value that assumes a nonnegative value, and sets a third constraint that the second margin value is equal to or greater than the difference between the upper bound of the allowable range and the residual dispersion. A calculation controller generates an objective function including the first, second and third constraints and including a summation of the first and second margin values for all paths, and derives a solution that minimizes the objective function.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Provided are a network node which has a wavelength switching cross-connection function and can thus interconnect paths of a wavelength-division-multiplexed optical signal and convert wavelengths, and an operating method of the network node. Accordingly, it is possible to provide a multi-degree cross-connection system having a simple structure at lower cost by allowing transmission of optical signals supposed not to be added/dropped at a network node without converting them into electrical signals and performing O/E conversion or E/O conversion only on optical signals supposed to be added/dropped at a network node. In addition, it is possible to increase the expandability of networks by regenerating degraded signals and which can effectively utilize bandwidths by grooming low-speed electrical digital hierarchy signals and transmitting them as high-speed optical signals.

Abstract: 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.

Abstract: 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.