Abstract: A method and apparatus to perform error correction is described. A stream of data is encoded using concatenated error correcting codes. The encoded data is communicated over a long-haul transmission system. The encoded data is decoded using the codes and three levels of decoding.

Abstract: A method for designing an optical system is disclosed. The optical system launches optical signals modulated with data into a fiber link having a property of inducing nonlinear distortion of the optical signals as a function of signal power of the optical signals and distance traversed in the fiber link. A Q-factor curve for the fiber link is determined as a function of the signal power. A signal power is preselected based on the Q-factor curve. The preselected signal power is associated with a set of channels. A coding gain is preselected based on the preselected signal power and a desired channel spacing for the set of channels.

Abstract: The present invention provides a method of detecting and correcting a fault in a signal transmission system. The method for detecting and correcting signal transmission faults in a signal transmission system includes bi-directional signaling on the same fiber, cable or signal line. A fault in a transmitted signal from a first upstream node to a second downstream node is determined by the loss or degradation of a signal simultaneously transmitted from the second downstream node to the first upstream node transmitted in the opposite on the same cable, signal line, or optical fiber. As a result, the aggregate propagation delay of the transmitted signals necessary for fault detection and fault notification is reduced and the amount of time to detect a fault and restore fault free signal transmission between one node and another node in a signal transmission systems is reduced, thereby increasing user satisfaction with minimal signal transmission interruptions even in the case of a transmission line fault.

Abstract: An apparatus comprises operationally coupled optical fiber segments that define an optical sublink. The optical sublink has link spans including a first link span and a second link span. The first link span has an average dispersion with a magnitude greater than zero. The second link span has an average dispersion with a magnitude greater than zero. The optical sublink has an end-to-end dispersion less than an end-to-end dispersion tolerance limit.

Abstract: Sealed cable connections can be used to connect first and second cables to a sealed cable joint. The sealed cable connection at one end of the sealed cable joint includes a cable socket body positioned within an inner region of a housing. The cable socket body includes a passageway receiving one of the cables. A seal securing member is positioned within the inner region of the housing and secured into contact with the cable socket body. At least one seal, such as a resilient metal seal, is compressed between the cable socket body and the seal securing member to seal against the inner surface of the housing. The sealed cable connection can also include a cable seal positioned around the cable and within the passageway of the cable socket body.

Abstract: A dispersion compensator provides dispersion compensation to a WDM optical signal having a plurality of channels located at different wavelengths and traveling in an optical transmission path. The dispersion compensator includes an optical splitter adapted to receive the WDM optical signal. The optical splitter has first and second output ports such that a subset of the plurality of channels are directed along the first output port and remaining ones of the plurality of channels are directed along the second output port. A dispersion compensating element is coupled to the first output port and a multiplexing element having a first input port is coupled to second output port of the optical splitter. The multiplexing element also has a second input port coupled to the dispersion compensating element and an output port on which the subset of channels and the remaining ones of the channels are recombined.

Abstract: The present invention is directed to a method and apparatus for improved long term signal attenuation performance of fiber optic cable and cable and/or fiber interface components. The improved long term signal attenuation performance of the fiber optic cable is achieved by introducing an additive that will occupy defect sites in the optical fibers, such as deuterium, into materials used in the fiber optic cable, either prior to or during the assembly process. The fiber optic cable casing structure then acts as a reaction chamber so that the additive which has been introduced during the fiber optic cable assembly process will react with the optical fibers so as to occupy defect site locations in the optical fibers. For example, the reaction of silica defect sites with deuterium improves the long term stability of the attenuation characteristics of the fiber optic cables because the number of defect sites available for hydrogen molecules to react with are reduced.

Abstract: An apparatus for communicating data through information channels each being associated with its own wavelength comprises modulators and an optical multiplexer. Each modulator is associated with its own wavelength. The optical multiplexer is operationally coupled to the modulators. The optical multiplexer receives multiple input optical signals each of which is received from its own modulator. Each input optical signal has its own dispersion substantially equal to a dispersion of each remaining input optical signals.

Abstract: A multi-body modular repeater system is capable of accommodating an increased number of fibers in an undersea fiber optic system. The system includes at least two repeater bodies connected in tandem with fiber optic cables coupled to the ends of the series of repeater bodies. A first plurality of optical fibers is amplified in one of the repeater bodies and a second plurality of fibers is amplified in the other repeater body connected in tandem. When the number of fibers in the fiber optic cable system is further increased, another repeater body may be added to accommodate the circuitry needed to amplify the additional fibers. In one embodiment, the repeater body housings are coupled together using an articulating joint that allows angular deflection of the repeater body housings while substantially preventing circumferential rotation of the repeater body housings with respect to one another. The articulating joint preferably allows angular deflection about at least two axes.

Abstract: A WDM optical communication system is provided that includes a transmitter and a receiver. An optical fiber transmission path couples the transmitter to the receiver. The transmission path includes at least one repeater having an optical amplifier located therein. A dispersion compensator is disposed at an intermediate point along the transmission path. The intermediate point is located outside of the repeater. The compensator includes a wavelength routing device for dividing a signal having a prescribed bandwidth into a plurality of distinct sub-bands. A plurality of output paths is provided for respectively receiving the plurality of distinct sub-bands. The dispersion compensator also includes a dispersion compensating optical element coupled to each of the output paths. Each dispersion compensating optical element substantially compensates for dispersion at a prescribed wavelength within the bandpass of its respective sub-band.

Abstract: A method and apparatus is provided that yields improved performance of both single channel and WDM long-distance optical transmission systems by synchronously modulating of the transmitted signal's amplitude. An amplitude modulator receives an optical signal onto which data has been modulated at a predetermined frequency. The modulator re-modulates the amplitude of the optical signal in a continues fashion with a waveform that is periodic, whose fundamental frequency is equal to the same predetermined frequency at which the data is modulated onto the optical signal. The resulting signal (which is neither a pure NRZ or RZ signal) is more tolerant to the distortions usually found in lightwave transmission systems, thus giving superior transmission performance.

Abstract: A method is provided for managing test measurements for an optical entity. The method can include determining if testing is needed, and building an object that includes a test variable and a plurality of independent variables. If testing is needed, the method can include measuring a test variable value, and revising the object to include the test variable value.

Abstract: A securing apparatus is used to secure an electronic component, such as a thermoelectric cooler in a thermoelectric cooling system. The securing apparatus includes a clamping mechanism that clamps the electronic component between a first plate, such as a heat sink plate, and a second plate, such as a mounting plate. The clamping mechanism applies compression forces to the electronic component to secure the electronic component without using shear forces capable of damaging the electronic component. The clamping mechanism preferably provides thermal isolation between the heat sink plate and the mounting plate.

Abstract: The present invention is directed to a method and apparatus for improved long-term signal attenuation performance of fiber optic and/or fiber interface components. The improved long-term signal attenuation performance is achieved by introducing an additive such as deuterium into materials used in manufacturing the fiber optic cable. The fiber optic cable casing structure may then act as a reaction chamber so that the additive will react with the optical fibers and occupy defect site locations in the optical fibers. With the additive occupying defect sites in the optical fibers, it mitigates the presence of hydrogen into those same defect sites.

Abstract: A method of increasing usable bandwidth on a long-haul cable system having at least one optical fiber, the method comprising the steps of: (a) effecting counter-propagating first and second signals of different bands on a common long-haul optical fiber having cascaded optical amplifiers; and (b) band amplifying the first and second signals while reducing BRS in the bands.

Abstract: A Raman amplifier is provided that includes at least a portion of optical fiber in which an optical signal travels. The optical fiber portion may encompass all or part of the optical transmission path of an optical communication system. A pump energy unit is provided that includes at least three pump sources providing pump power at different pump wavelengths. The different pump wavelengths are spaced apart from one another by nonuniform amounts so that a prescribed Raman gain profile is generated in the optical fiber portion. An optical coupler is provided for coupling the pump power to the optical fiber portion and transmitting the optical signal therethrough.

Abstract: A heat sink used in an electronic assembly includes mounting surfaces on a first side of a base portion and extended heat dissipating surfaces (e.g., fins) extending from a second side of the base portion. One or more electronic component boards, such as printed wiring boards (PWBs), are mounted to the mounting surfaces on the heat sink at one or more levels. Some of the mounting surfaces can be formed on mounting ridges, which define channels. Ventilation apertures located between the fins extend through the base portion such that air is drawn through the channels and up through the apertures creating a “chimney” effect. The heat sink is also grounded to at least one of the PWBS and electrically isolated from the chassis. Isolator bushings can be mounted in one or more of the fins for receiving pins extending from the chassis to insure mechanical support and isolation/dampening and to insure electrical isolation from the chassis.

Abstract: A method and apparatus is provided for transmitting an optical signal having a total number of channels that are dividable into a prescribed number of wavebands. The method includes the step of generating a first series of optical signals corresponding to each of the wavebands. The first series of optical signals includes a plurality of optical channels, which are sequentially numbered from 1 to N from lowest to highest wavelength. Within each waveband, a state-of-polarization of predetermined odd-numbered channels is oriented to be substantially orthogonal to a state of polarization of predetermined even-numbered channels by directing the predetermined odd-numbered channels and the predetermined even-numbered channels through orthogonally polarizing inputs of a polarization coupler. The odd-numbered channels and the even-numbered channels within each waveband may be directed through first and second wavelength combiners, respectively, prior to orienting their states of polarization.

Abstract: A method and apparatus to amplify an optical signal is described. A first filter splits an optical signal into a first and second parts. A first raman amplifier amplifies the first part. A second raman amplifier amplifies the second part. A combiner combines the amplified first and second parts.

Abstract: A method and apparatus is provided for managing dispersion in a WDM optical transmission system so that transmission performance is improved. The usable optical bandwidth of the transmission system is divided into sub-bands that individually undergo dispersion compensation before being re-combined. Accordingly, in comparison to known dispersion mapping techniques, more WDM data channels reside near a wavelength corresponding to the average zero dispersion wavelength.