A technique is provided for determining an optical transmission system description. The technique includes determining a dispersion map of the optical transmission system, placing a set of discrete cumulative dispersions onto the dispersion map, and defining a plurality of sequential system segments of the optical transmission system. Each system segment has an input point that corresponds to a point in the optical transmission system where the input cumulative dispersion matches a cumulative dispersion of the set of discrete cumulative dispersions. For each system segment, an input power of the system segment and a local dispersion value of the system segment is determined. Also, for each system segment, a sequence number of the system segments is stored. Furthermore, for each system segment, the input power and the local dispersion value determined in relation with the input cumulative dispersion of the system segment in a data repository is stored.

Disclosed are a chromatic dispersion estimation method and device in optical coherent communication, wherein, the method includes: performing a fast Fourier transform on IQ-imbalance compensated data to obtain frequency-domain data in two polarization directions; calculating autocorrelation sequences of the frequency-domain data and performing an inverse fast Fourier transform on the values of the autocorrelation sequences; calculating modulus squares of the results of the inverse fast Fourier transform, and adding the results in the two polarization directions to obtain; determining a mean value of s of a plurality of data sets; calculating an index of the maximum value of, and estimating a dispersion value of the optical fiber link according to the index of the maximum value of. The abovementioned technical solution allows a significantly accurate and rapid estimation of dispersion values.

This invention relates to a fiber optic fiber testing device presented in an app that compares three fiber link parameters against a table of specifications required in order for that fiber to transmit data at a particular speed. The invention presents a convenient ‘Pass’ or ‘Fail’ result for each parameter tested that immediately verifies whether the fiber being tested will meet the minimum basic criteria for transmission of data at a particular bandwidth speed, in accordance with that particular fiber manufacturer's specifications.

A state of polarization tracking recovery method and apparatus. The apparatus at least includes a processor configured to fit Stokes vectors to which predetermined symbols correspond of two states of polarization in a received dual-polarization multiplexing optical signal on a Poincare sphere to obtain a fitted plane. The processor calculates a compensation matrix for polarization-dependent loss (PDL) in a Jones space by moving a center of the fitted plane to the origin of the Poincare sphere, and calculates a demultiplexing matrix used for polarization demultiplexing in a Jones space by rotating the fitted plane with the center being moved to the origin until a normal vector of the fitted plane is parallel with a first axis of the Stokes space and rotating the fitted plane with the center being moved to the origin to a plane constituted by a second axis and a third axis of the Stokes space.

Joint estimation of the framer index and the frequency offset in an optical communication system are described among various other features. A transmitter can transmit data frames using pilot and framer symbols. A receiver can estimate the framer index and frequency offset using the pilot and framer symbols, and identify the beginning of a header portion of a data frame. By identifying the beginning of the header portion of a data frame, the receiver can synchronize, with less error, the data transmitted by the transmitter and the data it received. To further improve the framer index estimation, a lock indicator signal can be generated to signal to other receiver components that the estimated framer indices are reliable. The receiver can determine frequency offset and additional framer index estimations with increased reliability when performed after the lock indicator signal is generated.

[Problem] A signal distortion generated when a multi-level modulated optical signal is transmitted through an optical transmission path where optical amplifiers are scattered is suppressed and transmission quality is improved. [Solution] An optical transmission system 20 includes Tx 21a to Tx 21n configured to transmit a multi-level modulated optical signal 32 to an optical fiber 25, optical amplifiers 26a to 26f configured to amplify the optical signal 32 transmitted through the optical fiber 25, the optical amplifiers 26a to 26f being scattered on the optical fiber 25, and Rx 24a to Rx 24n configured to receive the amplified optical signal 32 via the optical fiber 25. A pre-dispersion compensation unit 27 of each of the Tx 21a to Tx 21n performs pre-dispersion compensation on the transmitted optical signal 32, based on a pre-dispersion compensation ratio for determining a percentage of dispersion compensation to be performed in advance on a wavelength dispersion to be accumulated in the optical fiber 25, with respect to the dispersion compensation to narrow a bandwidth to be widened by the wavelength dispersion during transmission of the optical signal 32 through the optical fiber 25.

Systems and methods for characterizing an optical fiber performed in part by an optical node (12) in an optical line system (10) include performing one or more measurements to characterize the optical fiber (16, 18) with one or more components (50, 52) at the optical node (12), wherein the one or more components (50, 52) perform functions during operation of the optical node (12) and are reconfigured to perform the one or measurements independent of the functions; and configuring the optical node (12) for communication over the optical fiber (16, 18) based on the one or more measurements. The one or more components can include any of an Optical Service Channel (OSC), an Optical Time Domain Reflectometer (OTDR), and an optical amplifier. The configuring can include setting a launch power into the optical fiber based on the one or more measurements.

An optical network device includes a receiver that receives a polarization multiplexed optical signal and a processor. The processor separates an electric field information signal indicating the polarization multiplexed optical signal into first and second polarization components orthogonal to each other, generates third and fourth polarization components by controlling the first and second polarization components, calculates an evaluation value corresponding to a power of the third or fourth polarization component for each of a plurality of positions on a transmission line, calculates a variation in the evaluation value for a control amount for each of the plurality of positions, and decides whether a first position is a position to be detected based on a result of comparing a variation in an evaluation value for the first position with a variation in an evaluation value for a second position adjacent to the first position.

A link extender configured to extend a range of an optical transceiver module is provided. The link extender includes an array of semiconductor optical amplifiers (SOAs) configured to amplify an optical signal received from the optical transceiver module, a first plurality of variable optical attenuators (VOAs) configured to control a power output of the amplified optical signal output from the array of SOAs, and a plurality of dispersion compensation and filtering (DC&F) devices configured to compensate for chromatic dispersion of the optical signal.

Local birefringence is determined from a scatter signature of a birefringent waveguide. Four copies of a Rayleigh scatter time delay domain signature of the fiber are collected from two orthogonal polarization received states and from two orthogonal polarization launched states to form a Jones transfer matrix. Obtaining the Jones transfer matrix for the waveguide eliminates the need to align the instrument polarization launch state to the birefringence axes. Birefringence is determined from an autocorrelation of a polarization state averaged function calculated from the transfer matrix terms. Alternatively, the transfer matrix is rotated until fast and slow eigenvectors are separated, fast and slow amplitude functions are generated, and a cross-correlation is performed on the fast and slow amplitude functions in order to determine the birefringence. Because the shift is determined at a high signal-to-noise level with improved sensitivity to the spectral shift, the local birefringence is determined more accurately.