An apparatus for mitigating polarization dependent loss (PDL) in an optical signal-to-noise ratio (OSNR) of a modulated optical signal is disclosed. The apparatus may comprise a spectrum analyzer to measure an optical power spectrum of a modulated optical signal. The apparatus may also comprise a measuring unit to select a first portion of the modulated optical signal and a second portion of the modulated optical signal, where each of the first and second portions of the modulated optical signals may include an independent noise distribution indicative of PDL, and measure a time-varying parameter of the first and second portions. The apparatus may also include a signal processor to PDL in an OSNR by transforming any elliptical polarization associated with the independent noise distribution into a ball polarization, determining a correlation between time-varying parameters of the first and second portions, and calculating a PDL mitigated OSNR.

In order to detect a terminal station in which a failure has occurred in a WDM optical transmission system that transmits optical signals transmitted thereto from a plurality of terminal stations after performing wavelength multiplexing of said optical signals, this failure detection device includes: an input unit that receives first optical signals from the plurality of terminal stations, the first optical signals having wavelengths respectively allocated to the plurality of terminal stations on the basis of allocation information, and that joins the received first optical signals; a monitoring unit that outputs monitoring signals, which are signals that are in accordance with the intensities corresponding to the respective wavelengths of the joined first optical signals; and an identifying unit that identifies a first terminal station from the plurality of terminal stations on the basis of the allocation information and the monitoring signals.

Systems and methods include receiving (S11) data for a plurality of elements associated with an optical network; determining (S12) an incremental noise penalty for each element of the plurality of elements based on the received data; and storing (S13) the incremental noise penalty for each element of the plurality of elements. The steps can further include determining (S14) Signal-to-Noise Ratio (SNR) across an optical path in the optical network by concatenating associated incremental noise penalties for each element in the optical path along with corrections. The present disclosure includes a fast, nonlinear estimation process with improved accuracy for low loss spans compared to traditional closed-form GN models, as well as a method to determine the coherent nonlinear penalty in an arbitrary concatenation of mixed heterogeneous fibers which is not considered by existing fast nonlinear interference calculation methods.

Provided is a monitoring apparatus capable of efficiently optimizing the transmission efficiency of an entire network. The monitoring apparatus (1) includes a variable parameter changing unit (2), a monitoring information acquisition unit (4), and an estimation unit (6). The variable parameter changing unit (2) changes a variable parameter for at least one of multiple network apparatuses that constitute an optical communication network transmitting an optical signal by wavelength division multiplexing. The monitoring information acquisition unit (4) acquires monitoring information related to a state of optical communication from at least one of the multiple network apparatuses. The estimation unit (6) estimates at least one penalty for a receiving side, using the monitoring information.

A decoder for determining an estimate of a vector of information symbols carried by optical signals propagating along a multi-core fiber in an optical fiber transmission channel according to two or more cores is provided. The decoder is implemented in an optical receiver. The optical signals are encoded using a space-time coding scheme and/or scrambled by at least one scrambling device arranged in the optical fiber transmission channel according to a predefined scrambling function. The decoder comprises a processing unit configured to adaptively: determine, in response to a temporal condition, one or more channel quality indicators from the optical signals; determine a decoding algorithm according to a target quality of service metric and on the one or more channel quality indicators; update the predefined scrambling function and/or the space-time coding scheme depending on the target quality of service metric and on the one or more channel quality indicators. The decoder further comprises a symbol estimation unit configured to determine an estimate of a vector of information symbols by applying the decoding algorithm to the optical signals.

A receiving device includes a light source, a wave multiplexer, a converter, a demodulator and a processor. The light source outputs local light. The wave multiplexer causes the local light to interfere with a received signal to acquire an optical signal. The converter converts the optical signal into an electrical signal. The demodulator demodulates the electrical signal to acquire a demodulated signal. The processor is configured to correct an error of the demodulated signal. The processor is configured to acquire a signal correction amount and/or an error rate. The processor is configured to control the light source in order to adjust an output intensity of the local light based on the signal correction amount and/or the error rate.

Embodiments of a device and method to automatically acquire signal quality metrics in a digital communication system are disclosed. The device may include acquisition means to sample the likelihood of a digital communication signal passing through a grid of time and amplitude regions, and storage means by which such likelihood measurements may be accumulated in a computer memory array for analysis. A state machine may execute a method that controls both the acquisition means and the storage means, requiring minimal intervention from supervisory systems.

Adaptive communications focal plane arrays that may be implemented in, e.g., a specially-configured camera that can be utilized to receive and/or process information in the form of optical beams are presented. A specialized focal plane array (FPA) having a plurality of optical detectors is utilized, where one or more optical detectors are suppressed such that data is not allowed to be output from the one or more suppressed optical detectors, and only a significantly smaller number or subset of optical detectors receiving optical beams are allowed to output data. In this way, the rate at which data is to be output by an adaptive communications FPA (ACFPA) can be significantly reduced.

A method for providing a maximum channel capacity per optical channel in an optical wavelength division multiplexing, WDM, transmission system is described. The WDM transmission system includes transceivers using multiple optical channels in a WDM channel grid to transport optical signals modulated with a modulation format with a signal symbol rate, SR, via an optical transmission link, OTL, along an optical path from a transmitting transceiver to a receiving transceiver. A channel capacity of the optical channel is maximized while a calculated channel margin, CM, is maintained above a preset minimal channel margin value.

A receiving apparatus includes a first processor configured to compensate, in a perturbation back-propagation (PBP) scheme, waveform degradation of an optical signal by traveling an optical transmission line due to a nonlinear optical effect; a memory; and a second processor coupled to the memory and the second processor configured to change a gamma coefficient to be used in the PBP scheme, measure reception quality of the optical signal for each of gamma coefficients obtained by the changing, specify a gamma coefficient in accordance with the reception quality from among the gamma coefficients obtained by the changing, and set the specified gamma coefficient as a parameter of the PBP scheme.