Abstract: In an optical module, a lens collects input light to generate a collected beam. A VIPA plate includes a reflective surface for highly reflecting light and a transmissive surface on which a reflection film having a lower reflectivity than the reflective surface is deposited. The VIPA plate causes multiple reflection of the collected beam within an internal area between the reflective surface and the transmissive surface, and emits diffracted light via the transmissive surface. A reflection mirror reflects outgoing light emitted from the transmissive surface to generate return light which returns to the transmissive surface. The reflection film includes a high-reflection film deposited on a portion from which the outgoing light of a high light intensity is emitted and a low-reflection film deposited on a portion from which the outgoing light having a lower light intensity is emitted.

Abstract: A waveform converting unit gives a change to a clock signal as a periodic voltage fluctuation that drives a pulse carver unit carrying out shaping into an RZ waveform. The pulse carver unit receives a bias voltage applied thereto from a bias voltage applying unit, is driven by the clock signal that is given a change by the waveform converting unit and that is amplified by an amplifying unit, and outputs an RZ pulse whose duty has been changed.

Abstract: A transmission-path-type specifying apparatus includes an optical filter that extracts a plurality of different wavelength components from light including wavelength components occurring at the time of communication; an optical switch that simultaneously transmits same pulse signals superposed on light of the extracted wavelength components. The apparatus also includes an ASE modulation controlling unit that obtains a delay-time difference among the transmitted pulse signals when arriving at a destination via a transmission path; a characteristic-value calculating unit that calculates a characteristic value of the transmission path corresponding to a reference time varied depending on the obtained delay-time difference and a type of the transmission path; and a fiber-type determining unit that specifies the type of the transmission path based on the calculated characteristic value.

Abstract: A system includes a laser generator, and a signal distortion generator circuit inline with the laser generator modulation signal and configured to generate distortion vectors in any of four distortion vector quadrants.

Abstract: An optical communication system includes logic to communicate using optical channels set outside a fiber zero dispersion zone, and having channel spacing that decreases with increasing distance from the fiber zero dispersion zone.

Abstract: A repeating apparatus disposed at an end point of each divisional repeating interval of a light transmission line performs a first dispersion compensation step, an optical add/drop multiplexing step and a second dispersion compensation step to perform repeating transmission. The ratio of an over compensation amount at the second dispersion compensation step to the sum of dispersion compensation amounts at the first and second dispersion compensation steps is set so as to gradually vary together with the transmission distance from the terminal apparatus for transmission at which the repeating apparatus is disposed on the light transmission line so that degradation of wavelengths to be received by the terminal apparatus for reception is suppressed while dispersion compensation is performed with a high degree of accuracy at each optical add/drop multiplexing point on the transmission line.

Abstract: A system and method for mitigating dispersion slope is capable of reducing the performance impact on an optical communication system caused by dispersion slope. The system and method receives an optical signal, demultiplexes the optical signal and optically filters the demultiplexed optical signals. The optical filters may have a bandwidth that is wide with respect to the demultiplexed optical signals and narrow with respect to the original optical signal.

Abstract: In the WDM optical transmission system, a high-slope dispersion compensator compensates wavelength dispersion produced in the optical transmission line. The high-slope dispersion compensator has a dispersion slope characteristic, by which a dispersion slope is substantially compensated over the wavelength bandwidth of the optical transmission line, and also a dispersion compensation characteristic, by which the residual dispersion produced after compensating the dispersion slope using the above dispersion slope characteristic becomes symmetrical with respect to a wavelength in the vicinity of the center of the wavelength bandwidth. To achieve the above compensation, a wavelength-multiplexed signal is divided into wavelength bandwidth groups, and the residual dispersion of the optical transmission line is compensated on a group-by-group basis for the wavelength bandwidth groups.

Abstract: A method for compensating for optical dispersion in an optical signal includes receiving an optical signal comprising a plurality of channels. The information being communicated in a first set of channels is modulated using a first modulation technique, and the information being communicated in a second set of channels is modulated using a second modulation technique. The method also includes compensating for optical dispersion in the optical signal such that dispersion compensation for the first set of channels is complete and such that dispersion compensation for the second set of channels is incomplete. In addition, the method includes splitting the optical signal into a first copy and a second copy, terminating the second set of channels in the first copy, performing additional dispersion compensation on the second copy such that dispersion compensation for the second set of channels is complete, and terminating the first set of channels in the second copy.

Abstract: The present invention provides an optical waveguide which comprises a core 4 for incident light and a core 5 for outgoing light, wherein the width of the core 5 for outgoing light is more than 1.5 times that of the core 4 for incident light. This optical waveguide permits the multiplexing and/or demultiplexing of light rays even when the wavelengths thereof undergo changes within the range of about 10 nm. In addition, the present invention further provides an optical multiplexer-demultiplexer which comprises the combination of an optical waveguide serving as an optical path and a diffraction grating for demultiplexing and focusing light, wherein the absolute value of the difference between the refractive index (nTE) of the core layer of the optical waveguide in the direction parallel to the plane of the film and that (nTM) of the core layer thereof in the direction perpendicular to the plane of the film is not more than 0.007 at the wavelength used.

Abstract: An optical transmission apparatus that performs optical transmission by wavelength multiplexing includes a receiving unit that receives a first optical signal transmitted from a transmitting device; a wavelength determining unit that determines wavelength of the first optical signal received by the receiving unit; a transmitting unit that transmits a second optical signal of varying wavelength; and a control unit that, based on the wavelength determined by the wavelength determining unit, controls wavelength of the second optical signal transmitted by the transmitting unit.

Abstract: Current optical networks are engineered to handle amplifier noise and chromatic dispersion. Polarization mode dispersion occurs in optical networks due splitting of the light energy of a pulse propagating in a fiber into two modes. Compensating for polarization mode dispersion is a difficult and expensive task and hence only few commercial systems have been deployed to deal with this issue. A polarization mode dispersion compensation module according to an example embodiment of the present invention compensates for polarization mode dispersion by determining a performance metric related to an error rate of an optical signal in at least one polarization mode in a filtered state. Based on the performance metric, a control vector is determined to control the optical signal in the at least one polarization mode in the filtered state. The control vector is then applied to a polarization effecting device to compensate for polarization mode dispersion.

Abstract: In an optical communications link, an optical system including: at least a first input port for delivering an optical signal travelling in the communications link, the optical signal including a plurality of wavelength channels, the channels being utilized for carrying optical information over an optical data link; a dispersive element for spatially separating the wavelength channels; an active optical-phase element; and a plurality of optical manipulation elements for directing the spatially separated channels between the dispersive element and the optical phase element wherein, the optical phase element independently modifies the phase of predetermined ones of the wavelength channel in a predetermined and decoupled manner for substantial compensation of signal degradation effects imparted to the wavelength channels by said communications link.

Abstract: A scheme is described for mitigating the effects of polarization-mode dispersion (PMD) in a wave-division multiplex (WDM) optical communication system having one or more transmission links with one or more quasi-static waveguide sections coupled by one or more non-static coupling sections. A transmitter is coupled to the transmission link and is adapted to transmit optical signals through the transmission link with wavelength channel spacing of the optical signals greater than about the PMD correlation bandwidth of at least one of the one or more quasi-static waveguide sections, so that the PMD induced outage probability for the system is optimized.

Abstract: The present invention provides: (1) a compensator that compensates a wide range of amount of dispersion of light in a wide bandwidth band; and (2) a variable dispersion slope compensator applicable to the case where a transmission path suitable for a wavelength division multiplexing transmission system produces a wavelength dispersion slope.

Abstract: A method of communicating digital information over a dispersive optical channel includes encoding the digital information into a plurality of data blocks, each of which includes a number of bits of the information. A time-varying electrical signal is generated which corresponds with each of said data blocks. The time-varying electrical signal is applied to an optical transmitter (122) to generate an optical signal which includes an asymmetrically amplitude limited transmitted signal modulated onto an optical carrier. The optical signal is then transmitted over the dispersive optical channel (106). At a receiving apparatus (104) the optical signal is detected to produce an electrical signal which corresponds with the asymmetrically amplitude limited transmitted signal.

Abstract: A residual chromatic dispersion target value at a terminal node is set for each wavelength path, and also, candidates of a dispersion compensation amount settable in each chromatic dispersion compensation module on an optical network are set, and further, computation processing is executed for selecting the dispersion compensation amount in each chromatic dispersion compensation module from the candidates so that the sum of errors between the residual chromatic dispersion amounts and the set residual chromatic dispersion target values at the terminal nodes for all of wavelength paths becomes minimum. As a result, for each wavelength path on the optical network, the dispersion compensation amount in each chromatic dispersion compensation module can be designed in optimum so as to satisfy the desired optical signal quality at the terminal node, while considering the residual chromatic dispersion during the transmission.

Abstract: The present invention relates to a method and system for high-speed bandpass serial data communication. A driver receives at least one data signal and generates a bandpass data signal for transmission through a bandpass waveguide interconnect. The bandpass data signal is launched into the bandpass waveguide interconnect using a first adaptor and extracted therefrom after transmission using a second adaptor. A receiver connected to the second adaptor recovers the at least one data signal from the extracted bandpass data signal. A dispersion compensation circuit receives one of the at least one data signal and the bandpass data signal and information indicative of a phase response of the bandpass waveguide interconnect and dispersion compensates the one of the at least one data signal and the bandpass data signal by compensating the phase response of the bandpass waveguide interconnect.

Abstract: Systems and method of compensating for transmission impairment are disclosed. One such method comprises: receiving an optical signal which has been distorted in the physical domain by an optical transmission channel; and propagating the distorted optical signal backward in the electronic domain in a corresponding virtual optical transmission channel.

Abstract: A dispersion compensation system comprises a detector for receiving an optical input signal and a compensator for processing the detector outputs and re-constituting the original signal. The detector generates at least two signals which depend on the instantaneous amplitude and frequency of the distorted signal in different ways, and the compensator electrically processes the detector outputs. The detector comprises a wavelength selective device (such as an asymmetric MZI) and two or more opto electronic detectors providing the electrical signals. The detector subtracts outputs of the MZI to provide frequency information and sums MZI outputs to provide amplitude information. The detector may have a dedicated amplitude detector. The compensator may have a local oscillator which is modulated by amplitude and phase or frequency information of the detector output signals, and the local oscillator may operate in the range of 11 to 100 GHz.

Abstract: This device for optically regenerating pulses includes a synchronous intensity modulator to provide time synchronization for pulses passing through it and to stabilize intensity fluctuations in the pulses. In addition, it includes noise suppression circuitry in the form of a saturable absorber that is distinct from the synchronous intensity modulator and the intensity fluctuations stabilizer.

Abstract: The present invention provides a wavelength division multiplexing system and a method and device for its residual dispersion compensation, wherein the device for residual dispersion compensation of wavelength division multiplexing system comprises: a performance parameter detecting device for receiving and detecting performance parameter of receiving terminal optical signal and sending detecting result of the performance parameter to a central control device; the central control device for deciding a dispersion regulating mode of a tunable dispersion compensator according to the detecting result of the performance parameter and sending the dispersion regulating mode to a tunable dispersion compensator control device through control signaling; and the tunable dispersion compensator control device for receiving the control signaling sent by the central control device and adjusting dispersion compensation amount of the tunable dispersion compensator according to the control signaling in order to make residual di

Abstract: In an optical transmission system including a transmitter Tx and a receiver Rx connected via a fiber link F, where the receiver Rx is adapted to utilize Forward Error Correction (FEC) on received signals, a polarization scrambler is provided at the transmitter Tx to scramble the polarization state of a transmitted signal, a polarization delay line is provided at the receiver Rx for controlling the polarization mode dispersion induced distortion of a received signal, a feedback unit is provided at the receiver Rx for providing a feedback signal based on at least part of the received signal, and at least one polarization controller interconnects the fiber link F and the polarization delay line. The power controller is operable based on the feedback signal to mitigate the polarization mode dispersion of the signal.

Abstract: A ring connection system and method are providing for distributing signals in an optical-to-electrical interface. The method electrically connects a plurality of nodes in a series-connecting ring, and receives an optical signal at a first node from a service provider. The method converts the optical signal to an electrical signal, and distributes the electrical signal via the ring. At each node, the electrical signal is supplied from a customer interface. Typically, each node has a plurality of customer interfaces. In one aspect, ITU-T G.984.3 Giagbit-capable Passive Optical Network (GPON) optical signals are received converted to a customer interface electrical signal such as an Ethernet connecting transfer mode, or time division multiplexed signal. Electrically connecting the plurality of nodes in the series-connected ring includes: series connecting the nodes in a North ring; and, series connecting the nodes in a South ring, opposite in direction from the North ring.

Abstract: An optical communication system and a communication network are disclosed herein capable of transmitting optical signals with high optical launch power over unrepeatered optical fiber links. A method of transmitting optical signals is also disclosed herein which comprises transmitting optical signals at high optical launch power over unrepeatered links.

Abstract: The invention relates to a network comprising at least one host device having an interface card connected to a backplane of said host device, wherein said interface card comprises at least one cage, for receiving a pluggable module which performs signal processing of data comprised of at least one WDM channel transported via at least one optical fibre connected to said pluggable module in the optical domain.

Abstract: An optical equalizer/dispersion compensator (E/CDC) comprises an input/output for receiving a multiplexed channel signal comprising a plurality of channel signals of different wavelengths. An optical amplifier may be coupled to receive, as an input/output, the multiplexed channel signals which amplifier may be a semiconductor optical amplifier (SOA) or a gain clamped-semiconductor optical amplifier (GC-SOA). A variable optical attenuator (VOA) is coupled to the optical amplifier and a chromatic dispersion compensator (CDC) is coupled to the variable optical attenuator. A mirror or Faraday rotator mirror (FRM) is coupled to the chromatic dispersion compensator to reflect the multiplexed channel signal back through these optical components The E/CDC components may be integrated in a photonic integrated circuit (PIC) chip.

Abstract: An object of the present invention is to realize a compensation circuit which can cope with rapidly fluctuating polarization mode dispersion, and the configuration thereof is a polarization dispersion compensation circuit for compensating polarization mode dispersion which takes place when a signal propagates on a transmission path, characterized by comprising: a front-end compensation part configured as a transversal filter for shaping a waveform subjected to polarization mode dispersion; and a data tracking/recovery part including a PLL-type data recovery circuit having a loop frequency band higher than the fluctuation frequency of polarization mode dispersion, and that tracks the temporal fluctuation of the polarization mode dispersion to recover data.

Abstract: An optical fiber delivery system for delivering ultrashort optical pulses that can efficiently transmit high peak power, ultrashort optical pulses from an optical pulse source to a desired position in an optical apparatus is provided. An optical system including such an optical fiber delivery system is also provided. The optical fiber delivery system includes light waveguide means 20 for receiving high-peak power, ultrashort optical pulses and transmitting the optical pulses, negative group-velocity dispersion generation means 30 for providing negative group-velocity dispersion to the optical pulses transmitted through the light waveguide means 20, and an optical fiber 40 that transmits the optical pulses transmitted through the negative group-velocity dispersion generation means 30 along a desired distance. The incident ultrashort optical pulses that have been injected into the light waveguide means 20 are converted into down-chirped pulses.

Abstract: A fiber optical system (10) for transmitting an optical signal comprises an optical fiber line (1) with a plurality of successively arranged polarization scramblers (6a to 6c) for polarization modulation of the optical signal transmitted through the optical fiber line (1) and a reference frequency signal (11) which synchronizes scrambling frequencies of all of the polarization scramblers (6a to 6c) to a common reference frequency.

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: A technique for generating variable pulse delays uses one or more nonlinear-optical processes such as cross-phase modulation, cross-gain modulation, self-phase modulation, four-wave mixing or parametric mixing, combined with group-velocity dispersion. The delay is controllable by changing the wavelength and/or power of a control laser. The delay is generated by introducing a controllable wavelength shift to a pulse of light, propagating the pulse through a material or an optical component that generates a wavelength dependent time delay, and wavelength shifting again to return the pulse to its original wavelength.

Abstract: The invention relates to an optical transmission system which allows high quality transmission of signal light, and has a configuration that is suitable particularly for CWDM optical transmission. In the optical transmission system, signal channels outputted from non-temperature controlled direct modulation light sources are multiplexed by a multiplexer, transmitted through an optical fiber transmission line, and demultiplexed into a first wavelength band ?1 and second wavelength band ?2 by a demultiplexer. The signal channel group in the second wavelength band ?2 of which the absolute value of chromatic dispersion is large is dispersion-compensated for by a non-temperature controlled dispersion compensator. The chromatic dispersion of the signal channels in the second wavelength band ?2 after passing through the dispersion compensator is set to be negative over a temperature range of 0° C. to 60° C.

Abstract: Fiber optic transmission technologies that allow DPSK or even higher order PSK to be performed at 20 gigabits per second per channel or even higher bit rates in a WDM (e.g., DWDM) wavelength multiplexed channeling environment. The technology employs pre-compensation of chromatic error dispersion such for each of most, if not all, channels have a portion of minimum absolute accumulated dispersion that occurs somewhere within the length (perhaps at the mid-point) of the optical channel. Post-compensation is then employed at the receiver to reduce or even potentially eliminate the chromatic dispersion. The technology allows for reduced bit error rates at high bit rates over even very long haul (e.g., trans-oceanic submarine or long terrestrial) optical fiber links, and for all channels.

Abstract: An optical transceiver is disclosed. The transceiver includes a receiver having adaptive electronic dispersion compensation (EDC) circuitry on at least one optical channel. The adaptive electronic dispersion compensation circuitry provides diagnostics information to a host system. The transceiver can be an XFP, X2, XENPAK, SFP, SFF, GBIC or other type of transceiver. The diagnostics information can include information on the time variation of a quality of the optical channel and/or a measure of a worst state of the optical channel over a period of time. The diagnostics information can also be derived from a measure of a quality of an equalized receiver signal, a current tap weight value, and many other specific values.

Abstract: The present invention relates to optical communication apparatuses such as OADM node, or OXC node. A receiving dispersion compensating module adjusts the accumulated dispersion of a wavelength-division-multiplexed optical signal such that the accumulated dispersion has an optimum value at a receiver for receiving optical signals in respective wavelength channels which are dropped from the wavelength-division-multiplexed optical signal. An auxiliary dispersion compensating module is provided in a path for an added wavelength group. The auxiliary dispersion compensating module applies the same value of dispersion as the accumulated dispersion adjusted by the receiving dispersion compensating module, to a wavelength-division-multiplexed optical signal in the added wavelength group.

Abstract: In an optical communications link, an optical system including: at least a first input port for delivering an optical signal travelling in the communications link, the optical signal including a plurality of wavelength channels, the channels being utilized for carrying optical information over an optical data link; a dispersive element for spatially separating the wavelength channels; an active optical-phase element; and a plurality of optical manipulation elements for directing the spatially separated channels between the dispersive element and the optical phase element wherein, the optical phase element independently modifies the phase of predetermined ones of the wavelength channel in a predetermined and decoupled manner for substantial compensation of signal degradation effects imparted to the wavelength channels by said communications link.

Abstract: An apparatus and method directed to testing and optimizing performance of an optical transmission system is disclosed, including at least one broadband dispersion compensation unit (DCU) or at least one depolarization device. The depolarization device may be used alone or in combination with the at least one broadband DCU. A method for optimizing performance of data channels in initial loading (IL) and full loading (FL) configurations of the optical transmission system is also disclosed.

Abstract: An optical fiber system comprising: (i) a dispersion pre-compensator including dispersion compensating fiber DCF characterized by the overall dispersion value DDCF at the operating wavelength ?; and (ii) a passive optical network (PON) including a plurality of transmission paths provided by a plurality of optical fibers, said plurality of transmission paths having a minimum and maximum dispersion value DMIN and DMAX; wherein the dispersion pre-compensator includes an output port operatively coupled to an input port of the a passive optical network and ?DMAX<DDCF<?DMIN.

Abstract: A dispersion compensator is applicable to a WDM optical transmission system and features low loss, wideband usage, and minimum ripple. The dispersion compensator is constructed so that the light emitted from a collimator will be reflected from an etalon of a 100% single-side reflectance by arranging the etalon and a mirror in parallel or with a slight angle and then enter another collimator. Elements for achieving variable dispersion compensation by changing temperature using a heater, for example, are also provided. In addition, these dispersion compensating elements are provided in multi-stage form and the angle of the mirror and the reflectance of the etalon are optimized. Thus, it becomes possible to realize a dispersion compensator applicable to a WDM optical transmission system and featuring low loss, wideband usage, and minimum ripple.

Abstract: A photonic bandgap fiber includes a core formed by a hole at its center, an outer cladding formed around the core, and an inner cladding formed between the core and the outer cladding, in which a two-dimensional Bragg grating is formed by periodically arranging a medium having a different refractive index. An optical fiber is connected to the photonic bandgap fiber, which has wavelength dispersion equal to or larger than 0 ps/nm/km and smaller than wavelength dispersion of the photonic bandgap fiber and D/S value, which is obtained by dividing the wavelength dispersion by dispersion slope, larger than D/S value of the photonic bandgap fiber.

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: A method is provided for dispersion compensation of an optical signal communicated in an optical network comprising a plurality of spans of low chromatic dispersion fiber. The method includes receiving an optical signal comprising a plurality of channels, where the information communicated in a first set of one or more of the channels is modulated using a first modulation technique and where the information communicated in a second set of one or more of the channels is modulated using a second modulation technique. The method also includes uniformly undercompensating for optical dispersion in the optical signal across all of the channels of the optical signal such that the accumulated dispersion in the optical signal increases with each span over which the optical signal is communicated. In particular embodiments, all of the channels of the optical signal are uniformly undercompensated in the range of approximately 60% to approximately 85% dispersion compensation for each span.

Abstract: Systems and methods for extended reach low differential latency optical networking with optical amplifiers and dispersion compensation modules configured to minimize latency between transmit and receive paths are provided. Additionally, systems and methods are provided for incorporating absolute time references wherein the relative accuracy of clock time between various servers used in various multi-site enterprises is required. The transport systems and methods are used in conjunction with low differential latency systems. The transport systems and methods provide that the differential latency between transmit and receive directions is maintained within about +/?5 microseconds of the transmit/receive path differential delay requirement in order to perform within the overall parameters of the low differential latency system architecture.

Abstract: An optical switch includes an optical waveguide to route an input optical beam. At least one polarization switch receives the input optical beam from the optical waveguide. At least one birefringent wedge is associated with the at least one polarization switch. The at least one polarization switch and at least one birefringent wedge operate to direct the input optical beam to two or more output locations through control of the polarization switch.

Abstract: A light dispersion filter is composed of three or more optically transparent layers each having a value equal to the value of the product of the refractive index and thickness of the optically transparent layer and transmitted light, and a plurality of partially reflective layers arranged alternately with the optically transparent layers and having predetermined reflectivities. Alternatively, a light dispersion filter has a plurality of etalon resonators which are arranged in series such that the value of the product of the refractive index of air and the interval of the etalon resonators is equal to the value of the product of the refractive index and thickness of the optically transparent layers.

Abstract: An optical switching apparatus includes at least one optical waveguide to deliver at least one input optical beam. A dispersion device spatially separates the at least one input optical beam into individual wavelength channels. An optical power device aligns the individual wavelength channels. An optical switch has at least one transflective polarizing element, at least one birefringent wedge and at least two polarization switches. The individual wavelength channels are directed to independently addressable regions of the polarization switches for wavelength selective switching. A second optical power device aligns the individual wavelength channels from the optical switch. A second dispersion device spatially combines individual wavelength channels from the second optical power device. At least one output optical waveguide receives at least one of the individual wavelength channels from the second dispersion device.

Abstract: An optical fiber transmits at least a signal light having a wavelength of 1550 nanometers in a fundamental propagation mode. The optical fiber has, a cutoff wavelength equal to or longer than 1550 nanometers, a wavelength dispersion of 4 ps/nm/km to 7 ps/nm/km in the fundamental propagation mode at the wavelength of 1550 nanometers, a dispersion slope of a positive value equal to or smaller than 0.03 ps/nm2/km in the fundamental propagation mode at the wavelength of 1550 nanometers, an effective core area equal to or larger then 60 ?m2 in the fundamental propagation mode at the wavelength of 1550 nanometers, and a bending loss equal to or smaller than 20 dB/m with a winding of 16 turns at a diameter of 20 millimeters in the fundamental propagation mode at the wavelength of 1550 nanometers.

Abstract: An optical communication system transmitting a plurality of channel wavelengths is provided. The system includes a transmitter unit, a receiver unit, and an optical transmission path interconnecting the transmitter and receiver units. The transmission path has a concatonation of optical fibers defining a dispersion map such that each of the channel wavelengths are located at FMX and XPM antiresonances at which FWM and XPM are suppressed.

Abstract: The present invention includes apparatus and method of a variable step size dithering control algorithm for polarization mode dispersion controllers (PMDCs). The dithering step size of the PCs is adjusted according to the feedback signal including degree of polarization (DOP).