Abstract: A system and method that enforces one or more policy rules on user-allocated bandwidth portions of the overall system bandwidth, for example in an optical fiber transmission system. The policy rules may limit, for example, the range of optical wavelengths, the acceptable range on the output-power-spectral density and/or the total per-band optical power within the user-allocated bandwidth that a user may provide on the system. The system may include one or more user control units that receives respective user output signals and applies all policy rules. The resulting optical output(s) of the UCU(s) may be provided an optical transmission path for transmission to a receiving terminal. In the receiving terminal, one or more UCU(s) may apply receiver policy rules, for instance by limiting the range of wavelengths transmitted to a receive subsystem.

Abstract: This spatial division multiplexing (SDM) in power-limited optical communication systems. In general, an SDM optical transmission system may be configured to increase data capacity over the data capacity of a non-SDM optical transmission system while maintaining power consumption at or below that of the existing non-SDM optical transmission system. To realize such an improvement in performance without increasing power consumption, an example SDM optical transmission may be constructed by reducing system bandwidth, reducing and/or altering equipment for filtering, reducing optical amplifier spacing, reducing operational amplifier power consumption, etc. In this manner, increased data transmission performance may be realized even where available power may be strictly limited.

Abstract: A system and method including a transmitter including digital signal processor for providing a shaped data output in response to an input data stream. The shaped data output is coupled to a modulator that modulates an optical signal in response to the shaped data output to provide a non-rectangular shaped output having channel spacing greater than Nyquist channel spacing. Providing a shaped output consistent the present disclosure mitigates the effects of non-linear impairments in an optical transmission system.

Abstract: A system and method including a parity bit encoder for encoding each n?3 bits of data to be transmitted with three parity check bits to produce blocks of n bits (n?3 information bits plus three parity bits associated with the n information bits). Each of the blocks of n bits are Gray mapped to three QAM symbols that are modulated onto an optical wavelength and transmitted to a receiver. A maximum a posteriori (MAP) decoder is used at the receiver to correct for cycle slip.

Abstract: A system and method with a modified bit-interleaved coded modulation with iterative decoding (BICM-ID). Coded and interleaved bits are combined and coded with a second FEC code that is then mapped to a modulation format. The second FEC code may be a single parity check (SPC) and the scheme may be referred to as a SPC-BICM-ID scheme.

Abstract: A system and method including a parity bit encoder for encoding bits of data to be transmitted with first and second parity check bits to produce successive block of bits. Each of the blocks of bits are Gray mapped to a plurality of associated QAM symbols that are modulated onto an optical wavelength and transmitted to a receiver. A de-mapper corrects for 90 degree and 180 degree cycle slip using parity indicated by the first and second parity bits.

Abstract: A system and method involving a coded modulation scheme whereby different spectral efficiencies can be achieved for different transmitters in a WDM system using the same M2-QAM modulation format. A maximum achievable spectral efficiency for the transmitters may be selected and a spectral efficiency step-size of the maximum achievable spectral efficiency may be specified. The spectral efficiency for any transmitter in the system may be individually selected by reducing its spectral efficiency from the maximum achievable spectral efficiencies by a selected number of steps corresponding to the step size.

Abstract: In general, a wavelength division multiplexed (WDM) communication system simultaneously pre-filters and combines groups of wavelengths with orthogonal polarizations to provide a pre-filtered, pair-wise orthogonal aggregate WDM optical signal. In particular, an orthogonally-combining interleaving filter multiplexer provides substantially orthogonal polarizations for odd and even channel wavelengths and simultaneously pre-filters and combines the orthogonally polarized odd and even channel wavelengths using interleaver optics. The orthogonal polarizations may be provided by orientation of PM input fibers or by a polarization rotator in the orthogonally-combining interleaving filter multiplexer.

Abstract: Dispersion may be managed in an optical network by allowing accumulation of dispersion to at least ten thousand ps/nm, and several tens of thousands of ps/nm in some embodiments. The accumulated dispersion may be returned to zero or near zero at a receiver and/or at one or more branch paths coupled to the transmission path.

Abstract: A system and method for fault recovery in a branched optical network. In response to a fault, power distribution in channels on recovering digital line segments is adjusted to minimize a merit function based on one or more system parameters.

Abstract: A system for fault recovery in an optical network may include an initial loading equipment (ILE) apparatus configured to supply power to a set of channels over a first communications link of the optical network, the set of channels including data channels and spare channels, and a control system configured to detect an optical power level over the data channels of the first communications link and determine whether a Q-factor corresponding to the data channels of the first communications link is below an error correction threshold, the control system configured to alert the ILE apparatus to adjust its optical power output over the spare channels upwardly based on the determination that the Q-factor is below the error correction threshold to increase the Q-factor.

Abstract: Techniques for communications using optical fiber are disclosed. An optical add/drop multiplexer (OADM) node includes an interface to a first fiber pair connecting a first trunk station and a second trunk station. The OADM node further includes an interface to a second fiber pair connecting the first trunk station and the second trunk station with a branch station. The OADM node includes a plurality of filters configured to provide connectivity between the first trunk station, the second trunk station and the branch station. Other embodiments are described and claimed.

Abstract: A repeater that enables both bi-directional optical time domain reflectometry (OTDR) and loop gain monitoring techniques that may be employed, for example, in particularly long repeater spans. In one embodiment, the repeater includes high loss loopback (HLLB) paths configured to couple test signals between incoming and outgoing fiber paths. The HLLB paths are coupled from the outputs to the inputs of amplifiers within the repeater and couple both OTDR and loopback signals from an outgoing fiber path to an incoming fiber path so that may be returned to line monitoring equipment that transmitted the test signals.

Abstract: A method and system for remotely upgrading a remote device may be used to upgrade application programs in devices that are difficult to access physically, such as undersea optical devices in an optical communication system. The method and system uses a Non-Erasable Application (NEA) to manage the upgrade of an application program, to determine if the application program is valid, and to provide default application functions if the application program is not valid. The NEA may be stored on a memory that is not remotely erasable and the application program may be stored on a memory that is non-volatile and programmable. Code status indicators may be used to indicate if the application program is valid, for example, to indicate that the code is present and functional.

Abstract: A conductive water blocking material and an optical fiber cable and method of constructing an optical fiber cable including the same. The cable includes at least one optical fiber and strength members disposed around the fiber. A conductor is disposed around the strength members. The conductive water blocking material includes a carrier material and conductive metallic particles and is provided in strength member interstices defined by the strength members.

Abstract: A system for fault recovery in an optical network may include an initial loading equipment (ILE) apparatus configured to supply power to a set of channels over a first communications link of the optical network, the set of channels including data channels and spare channels, and a control system configured to detect an optical power level over the data channels of the first communications link and determine whether a Q-factor corresponding to the data channels of the first communications link is below an error correction threshold, the control system configured to alert the ILE apparatus to adjust its optical power output over the spare channels upwardly based on the determination that the Q-factor is below the error correction threshold to increase the Q-factor.

Abstract: A system and method for generating soft decision reliability information from hard decisions in an optical signal receiver. The receiver may include a digital signal processor including a symbol reliability function for generating symbol reliability information associated with symbols encoded on optical signal. The symbol reliability information may be generated as a function of the symbols and hard decision outputs associated with the symbols.

Abstract: A system for signaling between elements in an undersea optical communication system including a cable signal generator. The signal generator includes line current modulation circuitry configured to impart modulation in line current provided on a power conductor of the transmission cable. A method of signaling between elements in an undersea optical communication system includes modulating a line current through an element and detecting the modulated current.

Abstract: A system and method including a parity bit encoder for encoding each n bits of data to be transmitted with a parity check bit to produce blocks of n+1 bits (n information bits plus one parity bit associated with the n information bits). Each of the blocks of n+1 bits are Gray mapped to a plurality of associated QAM symbols that are modulated onto an optical wavelength and transmitted to a receiver. A maximum a posteriori (MAP) decoder is used at the receiver to correct for cycle slip. Phase errors of 180 degrees may be detected by independently encoding odd and even bits prior to Gray mapping, and identifying errors in decoding odd numbered bits at the receiver.

Abstract: A system and method for blind equalization of a QAM signal. Equalization is achieved using an algorithm characterized by cost function that is a function the Euclidian distance, e.g. the minimum Euclidian distance, between points of the constellation associated with the QAM signal, i.e. the distance between symbols.