Abstract: Methods and systems for PMD compensation in an optical communication system are implemented by transmitting multiple optical signals through a common optical conduit to an optical compensator that adjustably rotates the polarization states of the multiple optical signals and transmits the rotated optical signals to an optical receiver. The receiver, upon sensing an excessive error condition, commands the optical compensator to change the polarization state of rotation, which changes the PMD profile of the received optical signals.

Abstract: In the dispersion-compensating system of the present invention, a demultiplexer demultiplexes optical signals in a signal wavelength band of 1520 nm to 1620 nm propagating through a first common transmission line into C band (1520 nm to 1565 nm) and L band (1565 nm to 1620 nm). Then, the demultiplexer outputs the optical signals of C band into a first branched transmission line and the optical signals of L band into a second branched transmission line. A first dispersion-compensating device is provided on the first common transmission line and compensates for the dispersion in C and L bands. A second dispersion-compensating device is provided on the second branched transmission line and compensates for the dispersion in L band, which has not fully been compensated for by the first dispersion-compensating device. Hence, the dispersion of optical transmission line can fully be reduced in a wide signal light wavelength band.

Abstract: A method and a system to produce, either in numerical simulations or in experiments, specified amounts of first, second and higher order PMD in a controlled manner, in particular large amounts. Parameters can be adjusted to obtain specific ranges of first, second and higher order PMD, and importance sampling can be used to determine the probability that the resulting PMD events can be obtained in realistic situations. Individual results obtained using specific parameter values can be combined to produce even larger ranges of PMD.

Abstract: A PMD emulator includes at least two polarization phase plates. The rotation matrix of the at two phase plates are varied to reduce the required number of phase-plates without reducing the number of birefringent segments used.

Abstract: An optical performance monitor (OPM) adapted to (i) sample an autocorrelation function corresponding to an optical signal transmitted in an optical network and (ii) based on the sampling, characterize two or more impairments concurrently present in the optical signal. In one embodiment, the OPM has an optical autocorrelator (OAC) coupled to a signal processor (SP). The OAC receives the optical signal from the network, generates two or more samples of its autocorrelation function, and applies said samples to the SP. The SP processes the samples and generates two or more signal metrics. Based on the signal metrics and reference data corresponding to the impairments, the SP then obtains a measure of each of the impairments.

Abstract: An optical transmission system capable of transmitting with high quality all the component signals of a signal lightwave having a broad total wavelength band and particularly suitable for the CWDM optical transmission, and an optical multiplexer and an optical demultiplexer for the system. Component signals outputted from optical transmitters are combined by an optical multiplexer, travel over an optical fiber transmission line, and arrive at an optical demultiplexer to be separated. They are received by optical receivers. The total transmission loss in the transmission line is smaller at wavelength ?b than at wavelength ?a. The insertion loss of the optical multiplexer or the optical receiver is larger at wavelength ?b than at wavelength ?a. The difference in power between the component signals having wavelengths ?a and ?b arriving at the optical receivers is smaller than the difference in the total transmission loss in the transmission line between wavelengths ?a and ?b.

Abstract: Dispersion compensation values are set so as to be transmittable to any path groups in a WDM optical communication system having OADM nodes, which includes transmitting-end and receiving-end terminal nodes; a WDM optical communication transmission line including a plurality of spans each having an optical fiber, the plurality of spans joining the transmitting-end and receiving-end terminal nodes; and a plurality of add drop multiplexing (OADM) nodes disposed on the optical communication transmission line; wherein when taking as the reference a residual dispersion target value of between the transmitting-end terminal and receiving-end terminal nodes, a residual dispersion target value for a node segment between one of the terminal nodes and one of the add drop multiplexing (OADM) nodes and a residual dispersion target value for a node-to-node segment between two of the add drop multiplexing (OADM) nodes are set so as to be proportional to ratios of the span counts in the node segment and in the node-to-node se

Abstract: The invention relates to the field of dispersion managed optical fibres for use in wavelength division multiplex transmission networks. A multimode optical fibre in which at least one higher-order mode can be propagated, is constituted radially by a single central core surrounded by an optical cladding (13), and comprises, for said higher mode or for at least one of said higher-order modes, positive chromatic dispersion optical fibre portions (D+) alternating longitudinally with negative chromatic dispersion optical fibre portions (D?).

Abstract: An optical interleaver for use in a range of telecommunications applications including optical multiplexers/demultiplexers and optical routers. The optical device includes an optical processing loop which allows multi-stage performance characteristics to be achieved with a single physical filtration stage. Optical processing on the first leg and second legs of the loop is asymmetrical thereby improving the integrity of the optical signals by effecting complementary chromatic dispersion on the first and second legs. A fundamental filter cell within the interleaver filters optical signals propagating on each of the two legs of the optical loop which intersects the fundamental filter cell.

Abstract: The present invention offers a compensation device having a transmission property for collectively compensating inclinations of accumulated transmission properties in a signal wavelength band of light signals of a plurality of channels configuring a wavelength-multiplexed light, among wavelength dependencies of transmission properties of a plurality of sets of light demultiplexers and light multiplexers.

Abstract: The invention includes an apparatus for modulating an optical signal. The apparatus includes a modulating mechanism comprising a plurality of modulating component arrays, each modulating component array comprising a plurality of modulating components, wherein adjacent ones of the plurality of modulating components in each modulating component array are separated by gaps, and wherein adjacent ones of the plurality of modulating component arrays are offset along a dispersion direction of an incident optical signal such that the gaps associated with the adjacent ones of the plurality of modulating component arrays are offset. In one embodiment, rows of the modulating components in the modulating component arrays are offset along the dispersion direction of the incident optical signal by a fraction of the modulating component pitch.

Abstract: An optical waveguide has a surface. An array of separately actuated bodies is disposed proximal to the exposed surface, and an actuator separately actuates at least some of the bodies to change a spectral characteristic of a wave propagating through the waveguide. Preferably, the bodies are metal striplines, an electro-optical material is disposed between the striplines and the exposed surface, and the actuator is a CMOS chip that imposes a voltage to some or all of the lines. The voltage changes the refractive index at the interface with the surface, changing an index of refraction profile of the waveguide and effectively imposing a grating. Alternatively, the bodies are micro-beams and the actuator, also controlled by a CMOS chip, separately moves each micro-beam into and out of proximity to the surface. The grating is programmable via the CMOS chip.

Abstract: In a chromatic dispersion and dispersion slope compensating apparatus according to the present invention, a WDM light which has been angularly dispersed to a first direction by a VIPA plate, is angularly dispersed to a second direction vertical to the first direction by a diffraction grating, and optical signals of respective wavelengths output from the diffraction grating are reflected by any one of a plurality of three-dimensional mirrors having reflective surfaces of curved shapes different from each other, to be returned to the VIPA plate. Thus, with a simple control mechanism in which the plurality of three-dimensional mirrors are moved to only the second direction, an apparatus capable of variably compensating for the chromatic dispersion and the dispersion slope independent of each other can be provided.

Abstract: A WDM (Wavelength Division Multiplex) terminal device located in a WDM network includes a multiplexing unit that multiplexes a wavelength of a client signal having a single wavelength or a wavelength of at least one of a first plurality of client signals whose wavelengths are multiplexed, to wavelengths of a second plurality of client signals received with their wavelengths being multiplexed, and transmits the second plurality of client signals. Thus, the WDM terminal device can multiplex wavelengths of a plurality of client signals received from a metro WDM terminal device located at a distant place, to a wavelength of another client signal without separating the plurality of client signals by each wavelength, thereby achieving accommodation of a plurality of client signals whose wavelengths are multiplexed, at low cost.

Abstract: A device (D) is dedicated to controlling the power of optical signals in a transparent switching node of an optical communication network that switches bands of wavelengths. The device includes, firstly, a controller (12) for comparing input optical power measurements to a selected first threshold and generating instructions representative of the comparison result, secondly, a measuring device (10A) for delivering measurements representative of the input optical power of the optical signals at one output at least of the switch (4), and thirdly, a processor between the switch (4) and the multiplexer (6) of the node and which control the optical power of the signals coming from the switch (4) as a function of the instructions they receive, so that the optical power of the signals at the input of the multiplexer (6) is maintained substantially constant.

Abstract: A wavelength multiplex transmission system is provided to reduce crosstalk among wavelengths and reduce deterioration of signals. At a transmission apparatus, one input signal is differentially divided into two; each of the two is converted to an optical signal; and then they are wavelength-multiplexed and transmitted. When crosstalk is arisen in the wavelength multiplex transmission system, the crosstalk is superposed on the two optical signals. The crosstalk is equally superposed on each of the signals with inverted polarities. Accordingly, converting the optical signals to electrical signals and then differentially combining them at a receiving apparatus, their signal components are accumulated, while their crosstalk components are cancelled out. Thereby, in the wavelength multiplex transmission system, deterioration of optical signals due to crosstalk can be reduced.

Abstract: In a dispersion slope compensator of the invention, angular dispersion of a WDM light in which the angular dispersion is already performed in a first direction (Y-axis) with a VIPA plate is performed in a second direction (X?-axis) perpendicular to the first direction with a diffraction grating, and the WDM light is reflected from a three-dimensional mirror and returned to the VIPA plate side. At this point, the three-dimensional mirror is mounted on a rotating stage while placed on a linear-moving stage, which moves the three-dimensional mirror in parallel in the second direction. Thereby, the rotating stage can adjust an angle of a reflection plane of the three-dimensional mirror with respect to an optical axis of the light focused with a lens, which allows optical axis shift of the reflected light to be corrected in the three-dimensional mirror according to setting of a chromatic dispersion compensation amount.

Abstract: This invention relates to an optical fiber and others having a structure for efficiently generating SC light while realizing high nonlinearity over a wide band. The optical fiber has at least a center core region, and an outside cladding region having a refractive index lower than that of the center core region and provided on an outer periphery of the center core region. The optical fiber has, as characteristics to light of a wavelength ?1 in a wavelength range of 1520 nm to 1620 nm, a chromatic dispersion of ?2 ps/nm/km to +2 ps/nm/km, a dispersion slope of ?0.009 ps/nm2/km to +0.009 ps/nm2/km, and a fourth-order dispersion of ?1.8×10?4 ps/nm3/km to +1.8×10?4 ps/nm3/km.

Abstract: Attenuation caused by dispersion in an optical fiber communications system is compensated. A number of low-speed channels is to be transmitted across an optical fiber. Each low-speed channel is allocated a different frequency band for transmission. The attenuation caused by dispersion is estimated for each of the frequency bands. The power of each low-speed channel is adjusted to compensate for the estimated attenuation. The power-adjusted low-speed channels are frequency division multiplexed together to produce an electrical high-speed channel suitable for transmission across the communications system.

Abstract: In the high-bit-rate transmission of optical signals in an optical transmission system having N optical fiber link sections with, in each case, one optical fiber and one dispersion compensation unit, the absolute-magnitude compensations of the first to Nth dispersion compensation units are dimensioned in such a way that the first to N?1-th fiber link sections is/are overcompensated, in each case, by approximately the same absolute magnitude overcompensation. Furthermore, the absolute-magnitude compensation of the Nth dispersion compensation unit is dimensioned in such a way that the accumulated fiber dispersion at the output of the optical transmission system is virtually completely compensated.

Abstract: The invention discloses an on-line dispersion compensation device for a wavelength division optical transmission system. The device is consisted of two optical path selectors and at least one chirped grating fiber unit. The chirped grating fiber unit is consisted of two chirped grating fibers with same wavelength band and connected oppositely. In addition, the chirped grating fiber unit is serially connected between the appropriate ports of the two optical path selectors. The invention applies a structure that combines a chirped grating fiber unit with two optical path selectors. The structure is suitable to on-line dispersion compensation in a DWDM system and has low insertion loss. When only a few wavelengths need to be compensated, the structure makes dispersion compensation with low cost, low insertion loss and compensating a large dispersion value. For single channel or broadband compensation, the invention provides dispersion compensation without through OADM or MUX/DEMUX filtering.

Abstract: The present invention discloses a high performance optical architecture for multiplexing and demultiplexing channels for use in high spectral efficiency optical systems. In general, the MUX and DeMUX architectures of the present invention will fall into two key sections or stages: a wavelength group section and a channel section. The group section makes use of characteristic associated with groups of multiplexed channels for separating said groups from an optical signal having a plurality of multiplexed groups. Advantageously, in preferred embodiments, the channel section is colorless (non-wavelength specific between groups) in order to reduce cost and complexity. With respect to the colorless channel section, components with free spectral ranges (FSRs) have been strategically added to provide repetitive optical filtering functions on group of channels (i.e., subsets of channels within each band of wavelengths) so that the colorless channel section can operate in any respective group identically.

Abstract: A monitoring system is described that is comprised of a processing system and a database system. The database system is configured to store identities for a plurality of channels in the communication network. The processing system identifies an error on a first channel of the plurality of channels. The processing system identifies a second channel of the plurality of channels that is adjacent to the first channel based on the database system and determines if an error occurs on the second channel. The processing system identifies a third channel of the plurality of channels based on database system and determines if an error occurs on the third channel. The processing system identifies polarization-mode dispersion based on determining the error occurs on the second channel and determining the error does not occur on the third channel.

Abstract: A transmitted optical signal is first subjected to polarization mode dispersion compensation by a polarization mode dispersion compensator (PMDC), and then, its chromatic dispersion is compensated by a variable chromatic dispersion compensator (VDC) after the polarization mode dispersion compensation. How much the optical transmission signal suffers from polarization mode dispersion, which is needed to perform the polarization mode dispersion is measured using a Stokes parameter that is not affected by chromatic dispersion.

Abstract: A compensator for compensating polarisation-mode dispersion, comprises a splitter (30) arranged to split light, according to the light's polarisation, between a first optical path and a second optical path; a combiner (40) arranged to combine light from the first optical path and the second optical path, and a monitor (15) for monitoring the light. An active wavelength-delay device (70) is provided in the first optical path and arranged such that components of the light travelling in the first optical path and having different wavelengths are subjected to different delays, the delays being selected according to an output from the monitor (15).

Abstract: Short haul optical communication networks using multi longitudinal mode lasers are susceptible to significant degradation from mode partition noise. Losses from such noise in short haul networks are substantially reducible by employing an additional fiber with specific properties. This additional fiber is chosen to have a slope for its wavelength versus dispersion behavior that is the negative of that for the transmission fiber.

Abstract: The wavelength multiplex transmission device of the present invention includes a block band unit (block dispersion compensating unit etc.) for subjecting a plurality of signal lights of different wavelengths to dispersion compensation on a band basis and outputting the compensated signal lights, a CW light output unit (CW light source unit etc.) for outputting a CW light which supplements power of the signal light, a band multiplexing unit for multiplexing all the signal lights output from the block band unit together with the CW light output from the CW light output unit, and a total band optical amplifier for amplifying all the signal lights multiplexed by the band multiplexing unit in the lump and transmitting the amplified signal lights to a transmission path.

Abstract: Included among the many structures described herein are photonic bandgap fibers designed to provide a desired dispersion spectrum. Additionally, designs for achieving wide transmission bands and lower transmission loss are also discussed. For example, in some fiber designs, smaller dimensions of high index material in the cladding and large core size provide small flat dispersion over a wide spectral range. In other examples, the thickness of the high index ring-shaped region closest to the core has sufficiently large dimensions to provide negative dispersion or zero dispersion at a desired wavelength. Additionally, low index cladding features distributed along concentric rings or circles may be used for achieving wide bandgaps.

Abstract: A plurality of optical repeaters are provided on a transmission line between an optical transmitting station and an optical receiving station. A combined transmission line section is provided between optical repeaters. The combined transmission line section is composed of the first optical fiber, which is a positive-dispersion fiber, and the second optical fiber, which is a negative-dispersion fiber. Signal light is inputted to the first optical fiber in each combined transmission line section. Each optical repeater inputs pump light to the second optical fiber.

Abstract: A polarization mode dispersion compensation apparatus using a photonic crystal structure includes an optical signal splitter for splitting and outputting incident optical signals into optical signals of a first and second polarization state; an optical signal combiner for combining and outputting the optical signals of the first and second polarization states; an optical signal guide having a photonic crystal structure having a first waveguide and a longer and variable second waveguide; a signal tab for externally outputting a portion of the optical signals and for outputting a portion of the optical signals to a feedback unit; a feedback unit for measuring a dispersion degree of the first and second polarization states inputted from the signal tab, and for outputting a feedback signal for removing the polarization mode dispersion; and an effective optical path length variation unit for varying an effective optical path length of the second waveguide.

Abstract: Methods and networks are disclosed for optimizing PMD measurements on an installed span of fiber. For a method of the invention, a light system transmits light over the installed fiber. A PMD measurement system measures PMD on the fiber over a time period based on the light. A temperature measurement system measures ambient temperatures of the fiber over the time period. The PMD measurements and the ambient temperature measurements are then processed to determine an optimal temperature range for performing future PMD measurements on the fiber. The optimal temperature range indicates the best temperatures to perform measurements, the best time of day to perform measurements, the best time of year to perform measurements (such as summer or winter), etc.

Abstract: Methods and systems for higher-order PMD compensation are implemented by developing an effective mathematical model and applying economical design techniques to the model. By assuming a constant precession rate for a narrow band of frequencies in an optical signal, a simplified model of a higher-order PMD compensator can be derived. The model can be used produce an economical compensator by making multiple uses of selected optical components.

Abstract: A dispersion compensator having relatively uniform transmission characteristics over the bandwidth of a communication channel. The compensator is designed to process an optical signal corresponding to the communication channel by decomposing that signal into spectral components, routing different components along different optical paths that impart relative delays between the components, and recombining the delayed components spatially and directionally to generate a processed optical signal with reduced chromatic dispersion. In one embodiment, the compensator is a waveguide circuit that includes four diffraction gratings operating in transmission and optically coupled to a tunable lens array, in which different tunable lenses receive light corresponding to different communication channels. For each channel, a desired group delay value is produced by selecting magnification strength of the corresponding tunable lens.

Abstract: An optical communication apparatus performs wavelength division multiplexing with respect to signals of a plurality of signal transmission bands. The apparatus includes a first optical unit which effects distributed Raman amplification and has a characteristic that compensates for dispersion of a transmission path to which the optical communication apparatus is connected, with respect to at least one of the signal transmission bands.

Abstract: A wavelength-division multiplexing optical transmission system for providing a compensating-purpose dispersion D2 to a wavelength-division multiplexing optical signal to be transmitted through an optical transmission path from a transmitter terminal to a receiver terminal. The compensating-purpose dispersion D2 satisfies conditions that at any wavelength “?” included in the transmission wavelength band, if dD1(?)/d??0 is established, then {dD1(?)/d?}×{dD2(?)/d?}<0 is also established, and if dD1(?)/d?=0 is established, then dD2(?)/d?=0 is also established, where D1 represents a dispersion generated in the wavelength-division multiplexing optical signal during when the wavelength-division multiplexing optical signal is transmitted through the transmission path from the transmitter terminal to the receiver terminal.

Abstract: Various configurations of a virtually imaged phased array (VIPA) generator in combination with a mirror to compensate for chromatic dispersion. A VIPA generator produces a light traveling from the VIPA generator. In some embodiments, a variable curvature mirror is positioned to reflect the light back to the VIPA generator. A rotation axis around which the mirror is rotated and a translation path for the rotation axis are provided, to change the curvature of the mirror where the output light is reflected. In other embodiments, a plurality of mirrors have different surface curvatures. A holder has a rotation axis and holds the plurality of mirrors equidistantly from the rotation axis. The holder is rotatable around the rotation axis to bring a different, respective mirror in position to reflect light produced by a VIPA generator back to the VIPA generator. In other embodiments, a rotating mirror is rotatable about a rotation axis to reflect light produced by a VIPA generator to a respective fixed mirror.

Abstract: Provided is an optical transmission line in which the suppression of SBS and the achievement of other transmission characteristics can compatibly be attained. The optical transmission line is formed by connecting a first optical fiber and a second optical fiber, or by connecting a group of first optical fibers and a group of second optical fibers, in which the difference in Brillouin frequency shift therebetween is 200 MHz or more. In at least one of the first optical fiber and the second optical fiber, the transmission loss may be 0.32 dB/km or less at a wavelength of 1383 nm. In each of the first and second optical fibers, the mode field diameter may be not less than 8.2 ?m and not more than 9.8 ?m, the cable cutoff wavelength may be equal to or less than 1260 nm, and the zero dispersion wavelength may be not less than 1300 nm and not more than 1324 nm.

Abstract: A WDM system includes a transmission station, a receiving station, a first optical path and a second optical path. The first optical path includes a first section and a second section, the second section being capable of compensating at least partially the dispersion accumulated by a series of optical channels along the first section. The series of channels includes at least a first plurality of channels having an average dispersion of the same sign in the first optical path. The system also includes at least a first conversion device, capable of inverting the spectrum and modifying the wavelength of at least the first plurality of channels, to produce a second plurality of channels having an average chromatic dispersion of the same sign in the second optical path.

Abstract: The invention relates to methods of producing and improving an optical transmission line comprising the combination of a line optical fiber and an original or modified module for compensating the chromatic dispersion of said line optical fiber.

Abstract: A chromatic dispersion compensator in a single-pass and a double-pass version is disclosed. In a single-pass version, the compensator has a diffractive grating for spatially separating an input optical signal into spatially spaced frequency components and a MEMS array of separate phase shifters, each for imparting an independent phase shift to a channel containing a range of the spatially spaced frequency components. In a double-pass version, a retroreflector is disposed to effect a double pass of the light beam through the grating and the phase shifters. The arrangement is effecting in reducing chromatic dispersion of the optical signal.

Abstract: A reconfigurable optical add-drop multiplexer is disclosed including an optical splitter receiving an input optical signal and splitting the input optical signal into a dropped optical signal and an express optical signal; a wavelength blocker optically coupled to the optical splitter, the wavelength blocker blocking particular wavelengths in the express optical signal; a cassette having a plurality of slots capable of accepting a plurality of pluggable optical filters; at least one pluggable optical filter optically coupled to the optical splitter, the pluggable optical filter filtering wavelengths so as to output a particular wavelength channel from the dropped optical signal; and an optical combiner optically coupled to the wavelength blocker and to an optical add path on which an optical add signal may be carried, the optical combiner combining the express optical signal having particular wavelengths expressed by the wavelength blocker and the optical add signal.

Abstract: This invention provides a technique for realizing low-cost optical signal waveform monitoring with improved realtimeness to be applied to signal quality monitoring in an actual optical transmission system, and a technique for stably controlling an optical transmitter/receiver and various compensators by means of this waveform monitoring. Opening/closing of a optical gate is controlled by means of a clock signal synchronized with an optical signal input from a photocoupler and having a period equal to the bit interval of data or N (N: a positive integer) times longer than the bit interval to allow each pulse of the optical signal for one bit of data to pass through the optical gate for only part of the time width of the gate. A photoelectric conversion element to which the optical signal transmitted through the optical gate for only part of the time width obtains an average light intensity of the input optical signal. Information on this average light intensity is output to a monitoring output section.

Abstract: Enhancement of the supercontinuum generation performance of a highly-nonlinear optical fiber (HNLF) is accomplished by performing at least one post-processing treatment on the HNLF. Particularly, UV exposure of the HNLF will modify its dispersion and effective area characteristics so as to increase its supercontinuum bandwidth, without resorting to techniques such as tapering or introducing unwanted reflections into the HNLF. The UV exposure can be uniform, slowly varying or aperiodic along the length of the HNLF, where the radiation will modify the nonlinear properties of the HNLF. Various other methods of altering these properties may be used. The output from the HNLF can be monitored and used to control the post-processing operation in order to achieve a set of desired features in the enhanced supercontinuum spectrum.

Abstract: A single-sided optical switching device for functioning as a dual switch wherein individual switches share common switching means is disclosed. The individual switches have separate ports and share common switching means formed by a moveable refractor, a single lens and a stationary reflector, wherein the movable refractor is positionable between the lens and the stationary reflector for redirecting light within ports of individual switches. An embodiment of the device provides a single-sided dual 2×2 bypass switch comprising a single lens and a single switching element.

Abstract: An optical apparatus for producing chromatic dispersion. The apparatus includes a virtually imaged phased array (VIPA) generator, a mirror and a lens. The VIPA generator receives an input light at a respective wavelength and produces a corresponding collimated output light traveling from the VIPA generator in a direction determined by the wavelength of the input light, the output light thereby being spatially distinguishable from an output light produced for an input light at a different wavelength. The mirror has a cone shape, or a modified cone shape. The lens focuses the output light traveling from the VIPA generator onto the mirror so that the mirror reflects the output light. The reflected light is directed by the lens back to the VIPA generator. In this manner, the apparatus provides chromatic dispersion to the input light.

Abstract: A dispersion-managed optical soliton transmission system uses alternating spans of positive-dispersion optical fiber having a negative slope and negative-dispersion optical fiber having a positive slope. For wavelength division multiplexing, the system has a map strength preferably between 4 and 8. An absolute value of average group velocity dispersion between 0.5 and 0.0 ps2/km, and soliton power may vary between channels within 1 dB. Map periods, amplifier spacings, and dispersion values across a wavelength range of 1530–1600 nm are disclosed for bit rates of 10 and 40 Gbits/sec to maintain the ranges of average group velocity dispersion and soliton power.

Abstract: A polarization mode dispersion (PMD) feedforward compensator compensates first and second order PMD. An optical signal is provided to a PMD detector that senses first and second order PMD in the optical signal and produces control signals for the PMD compensator. The PMD compensator comprises, in series, a first polarization controller, an adjustable delay, a second polarization controller, a first fixed delay, a third polarization controller and a second fixed delay.

Abstract: This disclosure is generally concerned with optical transceivers. In one example, an optical transceiver implements electronic dispersion compensation in the receive path, as well as optical preemphasis on the transmitted signal in order to improve aspects of optical performance on multimode fiber links, relative to systems that do not implement transmitter preemphasis. Among other things, such optical transceivers can be used to achieve longer link lengths over a given fiber and/or to improve the percentage of fibers that can be used with a given performance electronic dispersion implementation.

Abstract: Optical equalization across N (an integer, N>1) channels of a multi-channel link of a communications network, is accomplished by averaging effects of optical performance variations within each of the M (an integer, M>1) parallel data signals. At a transmitting end node of the link, each one of the M data signals are distributed across the N channels of the link. Thus a substantially equal portion of each data signal is conveyed through the link in each one of the N channels. At a receiving end node of the link, respective bit-streams received over the N channels to are processed recover the M data signals. As a result, bit error rates of the bit-streams received through each channel are averaged across the M data signals, all of which therefore have a substantially equal aggregate bit error rate.

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.