Abstract: A dispersion compensating apparatus includes a tunable dispersion compensator that dispersion-compensates an optical signal using a group delay property that is asymmetrical in bands outside an effective band; a set device that sets a dispersion compensation amount in the tunable dispersion compensator; and a shifter that shifts a central frequency of the effective band of the tunable dispersion compensator, based on the dispersion compensation amount set by the set device.

Abstract: A wavelength division multiplexing system has a wavelength division multiplexer and a wavelength division demultiplexer. The wavelength division demultiplexer is in series with the wavelength division multiplexer to process at least one optical signal to generate at least one processed optical signal. The wavelength division multiplexer and the wavelength division demultiplexer cooperate to introduce substantially zero total chromatic dispersion in the processed optical signal. In one version, the wavelength division multiplexer and the wavelength division demultiplexer introduce opposing functions of chromatic dispersion into the at least one processed optical signal.

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 a method and system for providing dispersion compensation in an optical system, there is coupled into the optical system at least one pathway into which there is connected a tunable chirped fiber Bragg grating, each such grating providing a respective tunable amount of dispersion. At least one respective DGD element is connected into the respective pathway for each such grating. The set of all such respective DGD elements in a given pathway introduces a bias differential group delay DGD(bias) having an absolute value that, for at least one tuning value of the grating, is substantially equal to differential group delay introduced by the grating.

Abstract: An optical network comprises a transmitter node (1), a receiver node (4) and an optical fiber (3) for transmitting an optical wavelength-division multiplex signal having payload channels and a supervisory channel between the nodes (1, 4). At least one of the nodes has an amplifier (8, 13) which is passed by the multiplex signal. The transmitter node (1) has a source (11) for the supervisory channel and a multiplexer (12) for combining the payload channels and the supervisory channel in order to form the optical wavelength-division multiplex signal, and the receiver node (4) has a sink (16) for the supervisory channel and a demultiplexer (14) for separating the wavelength division multiplex signal into supervisory and the payload channels.

Abstract: Digital compensation of the polarization-mode dispersion (PMD) effects experienced by an optical signal in a transmission link is achieved. A digital representation of the optical fields of two orthogonal polarization components of an optical signal, defined by a polarization beam splitter (PBS), is first obtained. The fiber transmission link is treated as a concatenation of multiple virtual PMD segments, each having two specific principle-state-of-polarization (PSP) axes and causing a differential group-delay (DGD) and a phase delay between two signal components that are polarized along the two PSP axes. The best guesses of the parameters of the PMD segments and the relative orientation between the PSP axes of the last PMD segment and the characteristic polarization axes of the PBS are dynamically obtained. The digital representation of at least one generic component of the field of the optical signal is then computed through matrix operations by using the best guesses.

Abstract: A chromatic dispersion compensation control method for compensating the chromatic dispersion of an optical transmission path with a variable dispersion compensator inserted in the optical transmission path is disclosed.

Abstract: An economic way of determining the chromatic dispersion along a link of a DWDM network is provided. A transmitter modulates the output signals of two lasers operating at two different wavelengths and the modulated output signals are sent into the link. Detectors at each one of a plurality of detection sites along the link determine a phase difference in modulation between the output signals of the two lasers. The chromatic dispersion for each detection site can be calculated from the modulation frequency and determined phase differences at that site.

Abstract: When line trouble occurs in an optical network, the restoration time can be reduced. A transponder 21 includes an active line and a standby line 43, and a transponder 22 includes an active line 42 and a standby line 44. The standby line 44 of the transponder 22 is accommodated in the same optical line as the active line 41 of the transponder 21. Upon detection of line trouble, the receiving transponder 24 acquires a VDC setting value for the active line 41, and sets the VDC setting value for the standby line 44 on the basis of the acquired VDC setting value.

Abstract: Systems and methods of compensating for transmission impairment over an optical transmission channel are disclosed. The optical transmission channel includes an optical fiber and an optical amplifier. One such method includes: receiving an optical signal which has been distorted in the physical domain by an optical transmission channel; and solving a non-linear Schrödinger equation (NLSE) using a split-step Fourier Method (SSFM). The NLSE describes a virtual optical fiber corresponding to the optical fiber. The SSFM implements a linear operator with a wavelet-based FIR filter.

Abstract: Systems and method of compensating for transmission impairment are disclosed. One such method comprises receiving a wavelength-division multiplexed optical signal. The received optical signal has been distorted in the physical domain by an optical transmission channel. The method further comprises propagating the distorted optical signal backward in the electronic domain in a corresponding virtual optical transmission channel. The backward propagation fully compensates for fiber dispersion, self-phase modulation, and cross-phase modulation (XPM) and partially compensates for four-wave mixing (FWM).

Abstract: An optical transmission apparatus and method thereof is provided. The optical transmission apparatus includes transmission units configured to transmit lights having different wavelengths, a multiplexing unit configured to multiplex lights transmitted from the transmission units, and a controller configured to control wavelengths of the lights, where the controller includes a wavelength spacing processing unit that controls a spacing between the wavelengths on the basis of reception state information of an apparatus that has received the multiplexed light.

Abstract: The invention relates to a very broad band wavelength multiplexed transmission system, typically having a bandwidth greater than 150 nm or 200 nm, and in which energy transfers between channels caused by the Raman effect are compensated. The depletion of channels at shorter wavelengths is compensated by amplification which is preferably distributed, while the enrichment of channels at longer wavelengths is compensated by attenuation.

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: An optical fiber transmission system including: a first transmission-line optical fiber to input first wavelength signal light output from a transmitter, and to change a waveform of the signal light; an optical coupler to combine the first wavelength signal light that has been propagated through the first transmission-line optical fiber with second wavelength pumping light; an optical limiter to input coupled light output from the optical coupler, saturating a gain as power of the coupled light increases using a nonlinear optical medium, thereby suppressing an optical noise component included in the coupled light, and to output signal light including the first wavelength optical component obtained from the nonlinear optical medium; and a second transmission-line optical fiber to input to a receiver after signal light output from the optical limiter is input and a waveform change by the first transmission-line optical fiber in the signal light is compensated for.

Abstract: An optical coupling device including: at least a first input port for delivering an optical input signal beam that includes a plurality of wavelength channels; at least a first optical output port for receiving an optical output signal beam; a wavelength dispersion element for spatially separating the plurality of wavelength channels in the optical input signal beam to form a plurality of spatially separated wavelength channel beams; an optical coupling device for independently modifying the phase of each of the spatially separated wavelength channel beams such that, for at least one wavelength channel beam, a selected fraction of the light is coupled to the first output port and a fraction of the light is coupled away from the first output port.

Abstract: By using wavelength division multiplexing technologies, redundant star topology network is constructed on a ring-shaped optical fiber network. Edge-switches 5a, 5b, 5c, and 5d are connected to client station groups 6a, 6b, 6c, and 6d are connected, respectively. The edge-switches 5a, 5b, 5c, and 5d are connected to edge optical transport device 2a, 2b, 2c, and 2d. Core-switches 4a and 4b are connected to a core optical transport device 1. The edge optical transport device 2a, 2b, 2c, 2d, and the core optical transport device 1 are connected to a ring-shaped single optical fiber 3. A communication circuit 7 is formed among core optical transport device 1, edge optical transport devices 2a, 2b, 2c, and 2d, by using wavelength division multiplexing technologies.

Abstract: A method and apparatus is provided for transmitting a WDM optical signal. The method begins by modulating a plurality of optical channels that are each located at a different wavelength from one another with a respective one of a plurality of information-bearing electrical signals The channel spacings between adjacent ones of the plurality of optical channels are selected such that the optical channels give rise to selected FWM terms that lie outside a channel bandwidth of the optical channels. Each of the modulated optical channels is multiplexed to form a WDM optical signal. The WDM optical signal is then forwarded onto an optical transmission path.

Abstract: An optical repeater device of the present invention comprises: a preamble compensating circuit 53, for taking out a normal data signal from burst signals propagating through a communication transmission path, and for adding a preamble signal before and/or after the data signal. Furthermore, the preamble compensating circuit 53 comprises: a detector circuit 53a, for inputting the burst signal, and for outputting only the normal data signal; a buffer circuit 53b, for storing the data signal output from the detector circuit 53a, and for outputting thereof; a preamble signal generation circuit 53d, for outputting at least one type of the preamble signal; and an data output select circuit 53e, for outputting the data signal at the time of the data signal input from the buffer circuit 53b, and for outputting the preamble signal from the preamble signal generation circuit 53d at any other time thereof.

Abstract: A chromatic dispersion monitoring apparatus according to the present invention comprises: a photodetector which photo-electrically converts an optical signal; a low-pass filter which limits a frequency bandwidth of the photo-electrically converted electrical signal to be within a range set according to a modulation format of the optical signal and a bit rate thereof; a DC elimination circuit which eliminates a direct current component of the bandwidth limited electrical signal; and a power detector which detects the power of the bandwidth limited electrical signal to detect the residual dispersion of the optical signal. As a result, it becomes possible to easily realize the chromatic dispersion monitoring apparatus of low cost, which is also capable to be arranged on an in-line.

Abstract: Provided is an ultra-short pulse light source having an optical pulse generator 111 for emitting short pulse light, an optical amplifier 112 for amplifying the short pulse light output from the optical pulse generator 111 and an optical compressor 120 for compressing the short pulse light. The optical compressor 120 has multi-step configuration of steps polarization beam splitters 1211,2, optical fibers 1221,2,1231,2 for compressing the incident pulse light, polarization rotating element 1241,2, for rotating the polarization direction of the incident light by 90 degrees to return the light to the optical fibers 1231,2, polarization maintaining optical fibers 1251,2 provided to the output side of the polarization beam splitters 1211,2, and a polarization maintaining optical fiber 1251 at the front step is connected to a polarization maintaining optical fiber 1252 at the rear step.

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: Embodiments of the present invention route a WDM signal across multiple communication paths using skew characteristics of at least some of the communication paths. The network is an optical transport network, using either circuit or packet based switching, and wavelength division multiplexed wavelengths and/or optical carrier groups (“OCGs”) over a fiber link to another node in the network. The plurality of communication paths involves different signal and path attributes such as a plurality of carrier wavelengths, optical carrier groups, physical communication paths (different nodes, different fibers along a same path, or any combination of the foregoing), or any other differentiating factors between two paths.

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: 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 transmission system in which a plurality of optical signals each having a different wavelength are transmitted via a single optical fiber, includes: a first dispersion compensator configured to compensate for wavelength dispersion based on a single wavelength of a plurality of signals transmitted via the optical fiber; a demultiplexer connected to the first dispersion compensator, splitting signals output from the first dispersion compensator into different channels according to their wavelengths, and outputting the same; and a plurality of second dispersion compensators connected to each channel split by the demultiplexer, and compensating for the wavelength dispersion of the mutually different wavelength optical signals.

Abstract: The power level of a wavelength division multiplexed optical signal is detected by a detection unit. When the power level of the optical signal detected by the detection unit is equal to or lower than a first threshold, the coupling direction of an attenuation unit for controlling the coupling direction for the ports of the optical signal is controlled in the direction orthogonal to the array direction of the ports. When the power level of the optical signal exceeds a second threshold, the coupling direction of the attenuation unit is controlled in the array direction of the ports.

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: A receiver for recovering transmitted information carried by a received optical signal that has been affected by dispersion includes an optical splitter having an input port arranged to receive the received optical signal, and a plurality of output ports. A proportion of optical power at the input port is transmitted to each of the output ports. A plurality of optical detectors is operably connected to respective output ports of the optical splitter, for generating a corresponding plurality of electrical signals. Optical phase shifters are disposed between the output ports of the optical splitter and respective optical detectors. As a result, each optical phase shifter applies a frequency dependent phase shift to an optical signal passing therethrough.

Abstract: The present invention provides a single fiber bidirectional optical transmission system capable of realizing the extension of a single fiber bidirectional long distance at a moderate price. An optical signal outputted from a second optical transmitter is incident on an optical amplifying portion passing through an optical circulator, a single fiber bidirectional transmission path, an optical circulator and an optical Blue/Red filter. The optical signal outputted from a first optical transmitter is incident on the optical amplifying portion passing through a dispersion compensator and the optical Blue/Red filter.

Abstract: In order to compensate for chromatic dispersion ad dispersion slope over an entire wavelength band of the optical signal, the wavelength band is split into a plurality of bands, and chromatic dispersion compensation is made to make chromatic dispersion in a central wavelength of each of the bands zero.

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: An optical transmission apparatus includes an optical add drop multiplexer (OADM) that adds/drops an optical signal to/from a transmission path. The optical transmission apparatus further includes a pump light multiplexer and a dispersion compensation fiber that are located downstream of the OADM on the transmission path. The optical transmission apparatus is configured to house a pump light source connectable to the pump light multiplexer to Raman amplify an optical signal in the dispersion compensation fiber.

Abstract: The present invention proposes a method whereby during a specified/specifiable observation period (Ttotal) , the polarization states of optical transmission system and/or the optical signals transmitted by the optical transmission system are changed by applying a targeted intervention in at least one position of the transmission line, and at a second position which is interposed at least one place downstream from the first position of the optical transmission line, a specified/specifiable signal characteristic (BER) is qualitatively measured and checked for adherence to a specified/specifiable threshold condition (BERth) and the PMD-induced outage probability of the optical transmission system is calculated on the basis of the ratio between the length of that share of the time (Tout), during which the measured signal characteristic fails to meet the threshold condition (BERth), to the length of the observation period (Ttotal).

Abstract: A communication network includes a starting node that has a variable dispersion compensator that performs dispersion compensation at a variable dispersion compensation amount such that a residual dispersion amount of an optical signal transmitted therethrough becomes a predetermined reference residual dispersion amount; and plural nodes that are subjected to dispersion compensation design using the starting node as a starting point and that include fixed dispersion compensators selected based on the reference residual dispersion amount.

Abstract: A colorless tunable dispersion compensator for compensating for chromatic dispersion in a multi-channel light signal is provided. The compensator includes a multi-channel Bragg grating extending along a waveguide. Dispersion tuning means, such as a temperature gradient inducing device, are provided for tuning the dispersion characteristics of the wavelength channels. Wavelength shifting means are also provided for uniformly shifting the central wavelengths of all channels independently of their dispersion characteristics. A uniform temperature inducing or strain applying assembly can be used for this purpose.

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: A regenerator (7.x, 7.1-7.3) for regenerating optical signals on optical transmission links (4), in particular for use in a Dense Wavelength Division Multiplex (DWDM) optical transmission system. The regenerator (7.x, 7.1-7.3) comprises optical amplification means (7.xa, 7.xd) for compensating optical power losses, and a deterministic adaptation unit (7.xb) comprising means being adapted to compensate deterministic transmission impairments of the optical transmission link (4), in particular optical dispersion compensating means being adapted to compensate for chromatic dispersion of said link (4). The proposed regenerator (7.x, 7.1-7.3) further comprises a non-deterministic adaptation unit (7.xc) comprising means for compensating time variant non-deterministic transmission impairments, in particular polarisation mode dispersion.

Abstract: A system and method for dispersion compensation of an optical signal in a hybrid network includes generating optical traffic in a first set of one or more channels, wherein the traffic in the first set of channels is modulated using a first modulation technique. Optical traffic is generated in a second set of one or more channels, wherein the traffic in the second set of channels is modulated using a second modulation technique. An optical dispersion pre-compensation is applied to the second set of channels. The first set of channels and the second set of channels are combined to form an optical signal, and the optical signal is transmitted over an optical network.

Abstract: The present invention provides methods and systems for mitigating polarization changes associated with an optical communication signal caused by mechanical disturbances to an optical fiber dispersion compensation module of an optical communication network. The methods include disposing a first damping material between an optical fiber and a housing associated with the optical fiber dispersion compensation module; wherein the first damping material is selected and positioned such that it mitigates relatively fast polarization changes. Optionally, the methods also include disposing a second damping material between the optical fiber and the housing associated with the optical fiber dispersion compensation module; wherein the second damping material is selected and positioned such that it mitigates relatively slow polarization changes. Thus, frequency range specific optical fiber dispersion compensation module mechanical perturbation isolation methods and systems are provided.

Abstract: A wavelength dispersion compensation control method determining whether a clock component is contained in an optical signal received from an optical transmission path and, if a clock component if contained in the optical signal, extracting the clock component, and stopping control of a variable wavelength dispersion compensator when no clock component is extracted.

Abstract: An optical processing method includes: receiving an optical signal from an optical system, wherein the optical signal is distorted by frequency-dependent polarization effects in the optical system; spatially dispersing frequency components of the distorted optical signal on a spatial light modulator (SLM); and independently adjusting the polarization transfer matrix of multiple regions of the SLM to reduce the distortion of the optical signal. A related optical processing method includes: providing a precompensation signal indicative of frequency-dependent polarization effects in a downstream optical system; spatially dispersing frequency components of an optical signal on a spatial light modulator (SLM); and independently adjusting the polarization transfer matrix of multiple regions of the SLM to at least partially precompensate the optical signal for distortions caused by the frequency-dependent polarization effects in the downstream optical system.

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 method of managing gain tilt in an optical transmission segment including providing an optical transmission segment having a plurality of fiber optic cable spans and a plurality of repeaters coupled to the fiber optic cable spans. Gain tilt in the optical transmission segment is monitored. If negative gain tilt is accumulated at a repeater location in the transmission segment, the repeater at the repeater location is replaced with a higher gain repeater having a higher nominal gain value than the nominal gain value of the repeater being replaced.

Abstract: One embodiment of the present invention provides a system for mitigating Raman crosstalk between downstream data and video transmission in an Ethernet passive optical network (EPON), wherein the EPON includes an optical line terminal (OLT) and one or more optical network units (ONU's). During operation, the system transmits a data stream from the OLT to the ONU's on a first wavelength that is substantially at 1490 nm. The system also transmits a video signal stream from the OLT to the ONU's on a second wavelength that is substantially at 1550 nm. The system modifies the bit sequence for the data stream to change the power spectral distribution (PSD) for the data stream, thereby reducing power spectral content in the frequency range where significant Raman crosstalk can occur between data and video signal streams.

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: 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: The present wavelength multiplexed optical system includes a multimode optical fiber that transmits wavelength multiplexed optical signals and a plurality of multimode modal dispersion compensation optical fibers. Each modal dispersion compensation optical fiber can transmit one of the multiplex wavelengths, and each modal dispersion compensation optical fiber has an optimized index profile such that the modal dispersion for the transmitted wavelength is approximately inversely equal to the modal dispersion induced in the multimode optical fiber. The wavelength multiplexed optical system facilitates an increased bitrate without reducing bandwidth.

Abstract: A low-cost configuration of, and at the same time to control the variable dispersion compensator at a high speed in a variable dispersion compensator for compensating the wavelength dependent accumulated dispersion resulting from the wavelength dependency of the transmission fiber and fixed dispersion compensator in a long-distance high-speed WDM transmission system. In order to achieve the object mentioned above, the wavelength dependent representative characteristic of the transmission fibers 4-1 . . . n, and the wavelength dependent representative characteristic of the DCFs 13-1 . . . n are recorded and maintained in advance in the dispersion control circuit 5-1 . . .

Abstract: An optical node apparatus according to the present invention amplifies a WDM signal light input to an input port, and thereafter, branches the amplified WDM signal light by an optical branching coupler to send the branched lights to first and second optical paths, and selects the light propagated through the first optical path by an optical switch to amplify the selected light by a post-amplifier, thereby outputting the amplified light from an output port, when the optical node apparatus is operated as an optical amplification repeating node. When the operational state is upgraded to an optical add/drop multiplexing node, an OADM section is connected between a set of connecting ports on the second optical path, and the adjustment of the OADM section is performed utilizing the WDM signal light branched by the optical branching coupler, and thereafter, the switching of the optical switch is performed to select the light on the second optical path side.