Abstract: A tunable dispersion compensator whose passband center wavelength changes when the amount of dispersion compensation is changed is suitably adjusted. The relationship between temperature for keeping the center wavelength constant and the amount of dispersion compensation is stored in advance. After controlling the amount of dispersion compensation to achieve best or optimum transmission quality, the amount of dispersion compensation is converted into temperature in accordance with the stored relationship and, based on that, the temperature is controlled to keep the center wavelength constant.

Abstract: A method of compensating for chromatic dispersion in an optical signal transmitted on a long-haul terrestrial optical communication system including a plurality of spans, including: allowing chromatic dispersion to accumulate over at least one of the spans to a first predetermined level; and compensating for the first pre-determined level of dispersion using a dispersion compensating fiber causing accumulation of dispersion to a second predetermined level. There is also provided a hybrid Raman/EDFA amplifier including a Raman portion and an EDFA portion with a dispersion compensating fiber disposed therebetween. An optical communication system and a method of communicating an optical signal using such a Raman/EDFA amplifier are also provided.

Abstract: An optical transmission system includes a number of corresponding modular multiplexing and demultiplexing units used in transmitting and receiving an optical signal respectively. Additionally, compensation components compensate for optical dispersion experienced by the optical signal. The modular multiplexing and demultiplexing units are assembled in a cascade fashion at the transmit side and the receive side of the optical transmission system, respectively. The dispersion compensation components share dispersion compensation fiber across the cascaded units.

Abstract: An optical extending device for use in transmission of optical signals which comprise at least one sequence of periodic optical signals, said optical device comprising: a first fiber optic having a characteristic dimensional propagation coefficient equal to ?1 and adapted to be connected to a single mode second fiber optic having a length equal to L0 and a characteristic dimensional propagation coefficient equal to ?0, wherein Lp, the length of said first fiber optic is substantially equal to {[T2/??L0*?0]/?1}*{1?MOD(L0/{T2/??L0*?0]/g(b)}} and wherein: n is an integer 1, 2, 3 . . . and is selected in accordance L0, the length of the single mode second fiber optic; T is a time period of the periodic optical signals; and MOD is the remainder obtained from dividing 10 by {[T2/??L0*?0]/?1}.

Abstract: An optical time-division multiplex signal processing apparatus includes an optical dispersion part providing optical dispersion to an optical time-division multiplex signal and an optical clock signal, an optical detector coupled optically to the optical dispersion part for detecting a beat signal formed between the optical time-division multiplex signal and the clock signal in a superposed state, and a filter connected to an output terminal of the optical detector for filtering out an electric signal of a desired frequency band from an output electric signal of said optical detector.

Abstract: The present invention relates to an analog optical transmission system having a construction for expanding an analog transmittable distance. The analog optical transmission system includes: a light transmitter outputting analog optical signals such as image signals modulated in accordance with electrical signals multiplexed on a frequency domain; a transmission line including a SMF of 20 km or less in the total length; and a light receiver. A dispersion compensating fiber compensating for the chromatic dispersion of the transmission line is arranged on the transmission line, and the dispersion compensating fiber satisfies one of the first condition that the chromatic dispersion is set at ?250 ps/nm/km or less and a length is set at 1.1 km or less, and the condition that the chromatic dispersion is set at ?330 ps/nm/km or less and a length is set at 1.2 km or less. Optical suppressing devices reducing the MPI noise are arranged at the end portion of the dispersion compensating fiber.

Abstract: A device and method for correcting for timing jitter of an optical data pulse in an optical transmission system. During transmission, a data pulse may suffer jitter. Its arrival time at a node may be temporally offset from its predicted arrival time. Data pulses are timed so that they may be received at a detector disposed downstream of the node at a predetermined time. The device includes a source of chirped optical pulses and a node, which has a first input arranged to receive a chirped optical pulse. The node has a second input arranged to receive a data pulse. The node includes an optical gate arranged to generate an output pulse in response to the first pulse and the data pulse received at the first and second inputs, respectively, having a wavelength dependent upon the time at which the data pulse is received at the second input. The device further includes an optically dispersive medium after passage through which, the output pulses are correctly retimed in order to correct for the timing jitter.

Abstract: The present invention provides devices and methods for Raman amplification and dispersion compensation. According to one embodiment of the present invention, a dispersion compensating device includes a dispersion compensating fiber having a dispersion more negative than about ?50 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; a Raman gain fiber having a dispersion more positive than about ?40 ps/nm/km over a wavelength range of about 1555 nm to about 1615 nm; and a pump source operatively coupled to the dispersion compensating fiber and the Raman gain fiber, the pump source operating at a pump wavelength, wherein the dispersion compensating fiber has a Raman Figure of Merit at the pump wavelength, and wherein the Raman gain fiber has a Raman Figure of Merit at least about equivalent to the Raman Figure of Merit of the dispersion compensating fiber, and wherein the dispersion compensating fiber and the Raman gain fiber are arranged in series between the input and the output of the device.

Abstract: An optical fiber having a length of one kilometer or more with average transmission loss at a wavelength of 1383 nm being less than average transmission loss at a wavelength of 1310 nm, wherein a maximum value of a transmission loss at the wavelength of 1383 nm of any one kilometer section along the entire length of the optical fiber does not exceed the average transmission loss at the wavelength of 1383 nm along the entire length of the optical fiber by 0.03 dB/km or more.

Abstract: An optical waveguide system exhibiting reduced noise includes a varying dispersion optical waveguide fiber and a high frequency electrical filter. The varying dispersion fiber shifts the frequency spectrum of the noise relative to that of the signal so that the noise can be filtered with substantially no effect on the signal. The varying dispersion fiber is a passive component of the optical system and is compatible with optical connecting and splicing.

Abstract: The present invention relates to a method for processing an optical signal is provided. An optical signal is input into an optical waveguide structure for providing a nonlinear effect. As a result, the optical signal undergoes chirping induced by the nonlinear effect. An output optical signal output from the optical waveguide structure is supplied to an optical bandpass filter to thereby extract components except a small-chirp component from the output optical signal. The optical bandpass filter has a pass band including a wavelength different from the wavelength of the optical signal. By extracting the components except the small-chirp component from the output optical signal in the form of pulse, it is possible to remove intensity fluctuations or accumulated noise especially at a top portion and/or a low-power portion of the pulse.

Abstract: The present invention provides devices and methods for dynamic dispersion compensation. According to one embodiment of the invention, a dispersion compensating device includes a negative dispersion fiber having an input configured to receive the optical signal, the negative dispersion fiber having a length and dispersion sufficient to remove any positive chirp from each wavelength channel of the optical signal, thereby outputting a negatively chirped optical signal; an amplifying device configured to amplify the negatively chirped optical signal; and a nonlinear positive dispersion fiber configured to receive the negatively chirped optical signal. The devices of the present invention provide broadband compensation for systems having a wide range of variable residual dispersions.

Abstract: An optical fiber transmission line composed of a plurality of segments each having a length falling within a predetermined range is provided. An optical transmitter for supplying an optical signal to the transmission line is provided at one end of the transmission line. An optical receiver for receiving the optical signal from the transmission line is provided at the other end of the transmission line. An optical amplifier is provided between any two adjacent ones of the segments. A dispersion compensator is provided in association with each of the optical transmitter, the optical receiver, and the optical amplifier. The dispersion compensator provides a dispersion selected from a plurality of stepwise varying dispersions determined according to the predetermined range.

Abstract: A system and method for reducing timing and amplitude jitter in trnasmission of Retrun-to-Zero modulated pulses is described. In the reduction of amplitude jitter the modulated pulses must be phase coherent. The method comprises the steps of measuring a total dispersion of a transmission fiber link, computing an optimal amount of pre-chirp to be added at an input of said transmission fiber link, computing an optimal amount of pre-chirp to be added at an output of said transmission fiber link, adding said optimal amount of pre-chirp to said input of said tranmisssion fiber link and adding said optimal amount of pre-chirp to said output of said tranmisssion fiber link.

Abstract: A system and method for modular multiplexing and amplification of optical signals in subwindows within an operating window of a fiber optic communication network. An operating window is divided into subwindows. Optical signals in each subwindow are optically amplified separately and in parallel by a plurality of optical line amplifiers. According to one embodiment, the operating window is divided into four subwindows within an erbium wavelength band. Each subwindow corresponds to a different group of channels having optical signals of a different wavelength. Modular wavelength division multiplexing (WDM) units multiplex/demultiplex optical signals in the set of multiple channels. A modular WDM unit includes a coarse WDM unit and four fine WDM units. The coarse WDM multiplexes optical signals by wavelength into subwindows separated by relatively large guard bands. A fine WDM unit further multiplexes optical signals within a subwindow by wavelength into individual channels with a fine separation.

Abstract: A method and apparatus for minimizing system deterioration caused by polarization effects (e.g., a polarization-dependent gain (PDG), a polarization-dependent loss (PDL), and a polarization mode dispersion (PMD)). The apparatus performs a signal modulation process to enable one bit to simultaneously contain two orthogonal polarization components, resulting in a minimum DOP (Degree Of Polarization). If a signal undergoes the PMD, the apparatus converts an NRZ (Non Return to Zero) signal into an RZ (Return to Zero) signal, resulting in minimum inter-symbol interference caused by the PMD. The apparatus can improve a performance of an optical signal during the PMD operation, whereas a conventional PMD compensation technique has been designed to remove system deterioration caused by only the PMD.

Abstract: The present invention relates to a method for regenerating an optical signal suitable for WDM (wavelength division multiplexing). In this method, an optical signal is supplied to an optical waveguide structure (e.g., optical fiber) for providing a nonlinear effect. As a result, the optical signal undergoes chirp induced by the nonlinear effect. Then, an output optical signal output from the optical waveguide structure is supplied to an optical filter to thereby remove a small-chirp component from the output optical signal. By removing the small-chirp component from the output optical signal in the form of pulse, intensity fluctuations or accumulated noise especially at a top portion and/or a low-power portion of the pulse can be removed. Accordingly, the optical signal can be regenerated independently of the bit rate, pulse shape, etc. of the optical signal.

Abstract: The dispersion managed solution for long haul, high speed D/WDM systems according to the invention operates on three closely related aspects of the communication system. One is provision of a new type of dispersion managed (DM) optical cable with improved dispersion performance over the existing unidirectional and bidirectional cables. Another aspect considered is providing a communication path implemented over DM cable with distributed Raman amplification, to obtain a transmission reach of 2000 km and more, without regeneration. Still another aspect of the dispersion management solution according to the invention is to provide ways of managing the end-to-end dispersion of a communication path, using the DM cable and taking into consideration all active and passive network elements in the respective path. Consideration is also given to the evolution of the path from simple to complex, as the user demand on more services grow.

Abstract: A method and apparatus is proposed for use in a communication system in which an optical communications path including a plurality of optical spans, each of the optical spans contributing nonlinear distortions to an optical signal passing there-through includes, providing a dispersion pre-compensation to the optical signal in the optical communications path, such that the limiting nonlinear effect that produces signal distortions for long-haul transmission is suppressed, prior to transmission through a plurality of optical spans, and providing a dispersion post-compensation to the optical signal in the optical communications path after transmission through the plurality of optical spans.

Abstract: The object of the present invention is to provide a compact dispersion slope equalizer by which it is possible to simultaneously recover distorted waveforms of WDM signals by dispersion slope of DSF or NZ-DSF at 1.55 ?m band, and to compensate for the dispersion of various fiber transmission lines having various dispersion values and variation of dispersion value caused by the temperature change or the like. WDM signals distorted by the dispersion slope of the fiber are introduced into an input waveguide, and are demultiplexed by a wavelength demultiplexer into each wavelength component, and pass through lattice-form optical circuits, transversal-form optical circuits, or the combination of these circuits. The dispersion slope of the signals is compensated for by these circuits. The recovered signals are multiplexed by a wavelength multiplexer, and the multiplexed light is outputted at an output waveguide. Arrayed-waveguide gratings can be used as the wavelength demultiplexer and multiplexer.

Abstract: At a receiver a 20 Gbit/s soliton bit stream (20) is demultiplexed into two 10 Gbit/s bit streams (22a, 22b) using a 2-way splitter (6), a clock extraction circuit (4), and a pair of polarization insensitive amplitude modulators (8a, 8b) exhibiting positive chirp. The outputs of the modulators are fed to detectors (7a, 7b) via lengths (9a, 9b) of optical fiber exhibiting normal dispersion thereby producing bit streams (23a, 23b) with increased mark/space ratio and reduced timing jitter.

Abstract: The invention relates to an optical receiving station, an optical communication system, and a dispersion controlling method for precisely controlling chromatic dispersion in an optical transmission line or chromatic dispersion in an optical transmission line that varies with time. An optical receiving station is provided with a dispersion compensating section for receiving, via an optical transmission line, an optical signal modulated according to an optical duo-binary modulation method and for changing a dispersion value to be used for compensating for chromatic dispersion in an optical transmission line, an intensity detecting section for detecting the intensity of a specific frequency component of the optical signal output from the dispersion compensating section, and a controlling section for adjusting the dispersion value of the dispersion compensating section so that the output of the intensity detecting section has a predetermined extreme value.

Abstract: Disclosed is an optical transmission system and module which includes a negative dispersion, dispersion compensating optical fiber coupled to a micro-structured optical fiber (such as band gap fiber, photonic crystal fiber or holey fiber) for compensating for the accumulated dispersion in a transmission fiber. The optical transmission system and module in accordance with the invention provides substantially equal compensation of total dispersion over an operating wavelength band, reduced overall system length, and lower insertion loss.

Abstract: Optical systems of the present invention include an electrical signal distortion compensator configured to electrically distort an electrical signal to offset optical distortion imposed by a Fabry-Perot filter on an optical signal corresponding to the electrical signal. The electrical signal distortion compensator can be used in an optical transmitter to distort the electrical signal prior to optical transmission, or in an optical receiver after optical transmission. The distortion compensation can be performed on a baseband signal or a modulated electrical carrier. Likewise, the distortion compensator can be deployed in combination with an optical receiver, which allows the use of the F-P filter-optical receiver combination with transmitters and receivers that do not include F-P filters or distortion compensators.

Abstract: An exemplary embodiment of the invention is a dispersion compensation module for compensating dispersion in a communications network. The dispersion compensation module includes dispersion compensating fiber having a dispersion coefficient that varies with wavelength. A thermal regulator adjusts the temperature of the dispersion compensating fiber to adjust the dispersion characteristic of the dispersion compensating fiber. Alternate embodiments of the invention include a communications system using the dispersion compensation module and a method for compensating dispersion.

Abstract: In order to provide a dispersion-compensating optical fiber able to be applied over a broad wavelength band, having a large effective area, and as a result, suppressing the occurrence of non-linear effects, the present invention comprises a dispersion-compensating optical fiber that compensates chromatic dispersion of a 1.3 ?m single-mode optical fiber over the entire wavelength range of 1.53-1.63 ?m characterized in that, chromatic dispersion at a wavelength of 1.55 ?m is ?50 ps/nm/km or less, the dispersion slope is negative over the entire wavelength range of 1.53-1.63 ?m, a cutoff wavelength is provided at which there is substantially single-mode propagation, bending loss is 30 dB/m or less, effective area is 20 ?m2 or more, and the absolute value of chromatic dispersion during compensation of the chromatic dispersion of a 1.3 ?m single-mode optical fiber serving as the target of compensation is 0.5 ps/nm/km or less.

Abstract: A dispersion compensation system and method for use in an optical transmission system to compensate for signal distortion of an optical signal is provided. The dispersion compensation system includes a first and second transceivers for generating and receiving the optical signal respectively. An optical line couples the first transceiver to the second transceiver. A plurality of amplifiers are coupled to the optical line, spaced periodically throughout the optical line forming span distances, where the amplifiers amplify the optical signal and where the span differences are variable. A plurality of dispersion compensation modules are coupled to the plurality of amplifiers where the dispersion compensation models include a coarse granularity module having a resolution of at least 5 kilometers connected to a connector, the connector also connected to a fine granularity module having a resolution of one kilometer.

Abstract: The present invention relates to an optical communication system including a structure for suppressing deterioration of transmission characteristics of signals added at each of nodes arranged in an optical transmission line, and a method of assigning signal channels. The optical communication system includes the optical transmission line for transmitting signals of plural channels between a transmitter and a receiver, and one or more nodes are arranged at predetermined positions of the optical transmission line. Each of the nodes includes an ADM for adding signals of a predetermined channel to the optical transmission line, and a signal channel at which the absolute value of accumulated-dispersion up to the receiver becomes smallest among signal channels which can be added is assigned to each of the nodes in advance or dynamically.

Abstract: The object of the present invention is to provide a compact dispersion slope equalizer by which it is possible to simultaneously recover distorted waveforms of WDM signals by dispersion slope of DSF or NZ-DSF at 1.55 ?m band, and to compensate for the dispersion of various fiber transmission lines having various dispersion values and variation of dispersion value caused by the temperature change or the like. WDM signals distorted by the dispersion slope of the fiber are introduced into an input waveguide, and are demultiplexed by a wavelength demultiplexer into each wavelength component, and pass through lattice-form optical circuits, transversal-form optical circuits, or the combination of these circuits. The dispersion slope of the signals is compensated for by these circuits. The recovered signals are multiplexed by a wavelength multiplexer, and the multiplexed light is outputted at an output waveguide. Arrayed-waveguide gratings can be used as the wavelength demultiplexer and multiplexer.

Abstract: An apparatus which compensates for dispersion in an optical transmission line. The apparatus includes a fixed dispersion compensator and a variable dispersion compensator. The fixed dispersion compensator has a fixed dispersion amount and coarsely compensates for the dispersion in the transmission line. The variable dispersion compensator has a variable dispersion amount and finely compensates for the dispersion in the transmission line. The fixed and variable dispersion compensators can be located at many positions. For example, one may be in a transmitter and the other may be in a receiver. Both may be in the transmitter and/or the receiver. One may be in either the transmitter or the receiver, with the other in an optical repeater positioned along the transmission line.

Abstract: The present invention relates to a dispersion compensating module or the like having a simple and compact structure. The dispersion compensating module comprises a plurality of dispersion compensators between its input and output ends and at least one or more optical switches disposed between these dispersion compensators. Each of the optical switches acquires signals reached from its first port and is switching-controlled so that the signals are outputted from one of its second and third ports. The dispersion compensating module controls the port switching operation of at least one of the optical switches, thereby adjusting the propagation line of the signals, i.e., the dispersion compensation amount.

Abstract: A dispersion compensating optical fiber ribbon comprising a plurality of coated optical fibers arranged in a parallel planar array, wherein each of the optical fibers exhibits at a wavelength of 1550 nm, a dispersion value of ?10 ps/nm/km or less, the dispersion slope of a negative value, and the transmission loss of not more than 1 dB/km.

Abstract: The present invention is directed to an integrated system for performing dispersion compensation on wavelength channels in WDM or DWDM transmissions. The system includes a tunable integrated dispersion compensation module that performs chromatic dispersion compensation and polarization mode dispersion compensation on each of the wavelength channels in the transmission. Feedback is used to adjust the tunable integrated dispersion compensation module until receiver performance is optimized.

Abstract: A system and method for transmission of data modulated spectrally enriched optical pulses via an error free propagation region of an optical fiber, in which the optical pulses generated by an optical transmitter have a spectrum that is substantially wider than the spectrum of Fourier-transform limit at an input of the error-free propagation region. The spectral width of the optical pulses gradually narrows while transmitting along this region and becomes comparable to the Fourier-transform limit at an output of this region. Linear and non-linear distortions are compensated within the error free propagation region respectively by deployment of dispersion compensating units and phase modulation of transmitted optical pulses for providing them with an appropriate frequency chirp having shape comparable with a frequency chirp induced by a self-phase modulation of the optical fiber but having opposite sign.

Abstract: An apparatus comprises an optical sublink including an operationally coupled optical fiber segments. The optical fiber segments are from a first optical fiber type, a second optical fiber type and a third optical fiber type. The first optical fiber type has a positive dispersion and a positive dispersion slope. The second optical fiber type has a negative dispersion and a negative dispersion slope. The third optical fiber type has one from the group of (1) a positive dispersion and a negative dispersion slope, and (2) a negative dispersion and a positive dispersion slope.

Abstract: A system and method for transmitting data modulated spectrally enriched optical pulses with a frequency chirp via an error free propagation region of an optical fiber, in which spectrum of optical pulses gradually depletes from the spectrum that is substantially wider than the spectrum of Fourier-transform limit at an input of the error-free propagation region and becomes comparable to the Fourier-transform limit at an output of this region. The gradual depletion of the spectrum is achieved by utilizing a frequency chirp converter having a dispersion sign opposite to a dispersion sign of the optical fiber.

Abstract: A dispersion managed link for transmitting wavelength division multiplexed (WDM) optical signals and method for providing the link are disclosed. The link includes a plurality of spans serially connected by optical amplifiers. Each span includes an optically dispersive fiber connected to a dispersion compensating module (DCM). The fibers and DCMs are selected in accordance with a preferred dispersion map, which represents dispersion along the link, such that points of minimum and maximum dispersion have distributions that change in accordance with one another. The effects of self-phase modulation (SPM), inter-symbol interference (ISI), and cross-phase modulation on the signals are minimized. The preferred dispersion map may be one of ramp type, angular type or arcuate type, and in the case of the latter two, it may have a plurality peaks.

Abstract: An object of the invention is to provide a method and apparatus of PMD compensation, which enable of compensating for polarization-mode dispersion (PMD) occurring in signal light, at high accuracy over a wide range.

Abstract: The present invention generally provides optical signal transmission system having an optical signal source, at least one optical signal regenerator in series communication with the optical signal source via an optical signal communications medium, a dispersion module in series communication with the at least one optical signal regenerator via the optical signal communications medium, and a receiver in serial communication with the dispersion module via the optical signal communications medium. The dispersion compensation module inserts an amount of lumped dispersion into the system, which operates to improve the signal transmission characteristics.

Abstract: The present invention provides devices and methods for dynamic dispersion compensation. According to one embodiment of the invention, a dispersion compensating device includes a negative dispersion fiber having an input configured to receive the optical signal, the negative dispersion fiber having a length and dispersion sufficient to remove any positive chirp from each wavelength channel of the optical signal, thereby outputting a negatively chirped optical signal; an amplifying device configured to amplify the negatively chirped optical signal; and a nonlinear positive dispersion fiber configured to receive the negatively chirped optical signal. The devices of the present invention provide broadband compensation for systems having a wide range of variable residual dispersions.

Abstract: An optical transmission system designed for gigabit pulse rates and Raman pumping in which there is essentially no pre-dispersion compensation and the in-line dispersion compensation at the start of each span is overcompensation of between 110 and 120 of the compensation needed to neutralize the dispersion of its immediately preceding span.

Abstract: An optical fiber has a section of the first kind having a chromatic dispersion not less than a given positive value x and a negative chromatic dispersion slope at a given wavelength and a section of the second kind has a chromatic dispersion not more than −x and a positive chromatic dispersion slope at the same wavelength. Another optical fiber has a chromatic dispersion higher than a positive value x and a negative chromatic dispersion slope at a given wavelength band.

Abstract: An optical dispersion compensation device includes a first optical compensation unit that applies non-linear dispersion compensation across a signal band, the first optical compensation unit being coupled to a second optical compensation unit that applies a degree of linear dispersion compensation across the signal band. The approach taken is to provide broadband dispersion compensation by applying dispersion slope compensation across the signal band to equalise residual dispersion slope and by applying a degree of linear compensation separately to affect the required linear dispersion compensation. Using these two degrees of freedom it is possible to set the desired dispersion slope and linear dispersion (whether positive or negative) to affect broadband dispersion compensation without needing to demultiplex the optical signal.

Abstract: A low coherent reflectometer uses low coherent beams for measurement of refletance and refleting positions with respect to a measured optical circuit which includes a reflecting point. The low coherent beams are branched to produce measurement beams (DL) and local beams (KL), so that the measurement beams are introduced into a first optical path, which includes a dispersion shifted fiber, towards the measured optical circuit, while the local beams are introduced into a second optical path which includes a spatial optical path terminated by a reflecting mirror. Refleted measurement beams (RL) and reflected local beams are combined together to produce combined beams, which are subjected to processing and analysis.

Abstract: A method for determining interactions between a number of optical channels in a wavelength division multiplexed signal wherein, given that during broadband optical transmission, the quality of a “Dense Wavelength Division Multiplexed” signal is adversely affected by multiple channel interactions, the method is used to determine the governing effects, the Kerr effect and the non-linear scattering process by evaluating the spectral profile of the Q factor or of the bit error rate.

Abstract: An optical fiber (12a) with a large effective core area and a large chromatic dispersion value is disposed on an input side of signal light, and an optical fiber (12b) with a small effective core area and a small chromatic dispersion value or a chromatic dispersion value of negative polarity is disposed on an output side of the signal light. A pumping light source (14) generates pumping light of 1450 nm to cause Raman amplification of 1550 nm in the optical fiber (12b). The output light from the pumping light source (14) enters the optical fiber (12b) from the back through a WDM optical coupler (16). Provided that y=(Pin−&agr;)/(Pp·10 Log L) where input power of the optical fiber (12a) (i.e.

Abstract: An object of the present invention is to realize almost the same transmission characteristic in all wavelengths at a transmission rate of 10 Gb/s or more. An optical transmitter 10 outputs WDM signal light multiplexed with signal light of a plurality of wavelengths toward an optical transmission line 12. The optical transmission line 12 comprises an optical transmission fiber 14, an optical repeating amplifier 16 and a dispersion compensating fiber 18. The gain characteristic of the optical repeating amplifier 16 is set so that the gain becomes the maximum at the effective zero dispersion wavelength of the optical transmission line 12 and that lowers inversely proportional to the distance from the effective zero dispersion wavelength. The whole optical transmission line 12 is set so that the peak power deviation between the effective zero dispersion wavelength &lgr;0 and the wavelength &lgr;1 or &lgr;n on both end becomes approximately 4 dB.

Abstract: A dispersion compensation module (DCM) for compensating dispersion of an optical fiber transmission link is provided. The optical fiber transmission link comprises a transmission fiber and the DCM. The DCM comprises at least first and second dispersion compensating fibers, DCF1 and DCF2, respectively. DCF1 and DCF2 each have a dispersion, D1 and D2, respectively, a dispersion slope, S1 and S2, respectively, and a relative dispersion slope, RDS1 and RDS2, respectively. The transmission fiber also has a dispersion, DTransFiber, a dispersion slope, STransFiber, and a relative dispersion slope, RDSTransFiber. DCF1 and DCF2 are selected based on their respective relative dispersion slopes, RDS1 and RDS2, respectively. DCF1 and DCF2 have particular, lengths, L1 and L2, respectively.

Abstract: An optical transmission system includes a number of corresponding modular multiplexing and demultiplexing units used in transmitting and receiving an optical signal respectively. Additionally, compensation components compensate for optical dispersion experienced by the optical signal. The modular multiplexing and demultiplexing units are assembled in a cascade fashion at the transmit side and the receive side of the optical transmission system, respectively. The dispersion compensation components share dispersion compensation fiber across the cascaded units.

Abstract: A dispersion management optical transmission system obtained by connecting a positive fiber having a positive dispersion in the 1.5 &mgr;m band and a negative fiber having a negative dispersion, suppressing dispersion in the 1.5 &mgr;m band, suppressing the occurrence of non-linear phenomena, and reducing the transmission loss and an optical transmission line using the same, wherein the dispersion of the positive fiber in the 1.55 &mgr;m band is 8 to 15 ps/nm/km and the dispersion slope is at least 0.04 ps/nm2/km, the dispersion of the negative fiber in the 1.55 &mgr;m band is not more than −40 ps/nm/km and the dispersion slope is not more than −0.08 ps/nm2/km, the cumulative dispersion of the positive fiber is at least 200 ps/nm, and the average dispersion when combining the positive fiber and the negative fiber module is suppressed to any wavelength region of the 1.5 &mgr;m band.