Abstract: A method of optical signal adjustment may include obtaining a number of bits per second of data transmission in a frequency channel of an optical network. The method may also include directing a reduction in a number of bits per symbol transmitted in the frequency channel and directing an increase in a number of symbols transmitted per second in the frequency channel to maintain the number of bits per second of data transmission in the frequency channel.

Abstract: According to an aspect of an embodiment, operations may include obtaining a first waveform profile corresponding to an optical signal received at an optical receiver via an optical link between the optical receiver and an optical transmitter. The operations may also include obtaining a second waveform profile that is an estimate of the first waveform profile. The second waveform profile may be based on one or more properties of the optical link and may be based on a complex scaling factor that accounts for rotation of the optical signal as the optical signal propagates via the optical link. In addition, the operations may include determining a power profile estimation corresponding to the optical link based on a comparison between the first waveform profile and the second waveform profile.

Abstract: In an example, a method may include obtaining anomaly characteristics associated with an anomaly in a transmission medium in an optical transmission system. The anomaly may cause a degradation in one or more signal characteristics of an optical signal traversing the transmission medium. Based on the anomaly characteristics, the method may also include adjusting a first output power of a first optical amplifier that may be disposed at an input end of the transmission medium. Alternatively, or additionally, based on the anomaly characteristics, the method may also include adjusting a second output power of a second optical amplifier that may be disposed at an output end of the transmission medium.

Abstract: A method may include directing transmission of a first optical noise signal along a frequency channel of an optical network at a first power level. The first optical noise signal may include a notch at a frequency in the frequency channel. The method may also include while transmission of the first optical noise signal occurs along the frequency channel, obtaining a measurement of a first noise level at the frequency and obtaining a measurement of a second noise level at the frequency. The frequency channel may include a second power level when the measurement of the second noise level is obtained and the second power level may be different than the first power level. The method may further include estimating a noise level of an optical data signal transmitted along the frequency channel based on the first noise level and the second noise level.

Abstract: A method may include directing transmission of a first optical noise signal along a frequency channel of an optical network at a first power level. The first optical noise signal may include a notch at a frequency in the frequency channel. The method may also include while transmission of the first optical noise signal occurs along the frequency channel, obtaining a measurement of a first noise level at the frequency and obtaining a measurement of a second noise level at the frequency. The frequency channel may include a second power level when the measurement of the second noise level is obtained and the second power level may be different than the first power level. The method may further include estimating a noise level of an optical data signal transmitted along the frequency channel based on the first noise level and the second noise level.

Abstract: An example method may include obtaining multiple symbols each associated with a different state in a quadrature amplitude modulation scheme used for transmission of a data signal. The method may further include determining a sequence of symbols of the multiple symbols for a first portion of the data signal. The determining may include selecting an index value from multiple index values for the first portion of the data signal. The determining may also include obtaining energy states of multiple sequences of the symbols using the energy levels of the symbols. The determining may further include obtaining a relationship between the energy levels of the symbols, the energy states of the multiple sequences of the symbols, and the multiple index values. The determining may further include selecting the sequence of symbols based on the relationship and the index value for the first portion of the data signal.

Abstract: Systems and methods for constellation shaping using low rate loss bit-level distribution matchers include receiving blocks of input bits and, for each input block of a predetermined size, assigning a respective codeword of a predetermined output block size. The number of bits of a given bit value in the codeword is dependent on a predetermined target probability distribution. A one-to-one mapping exists between each possible combination of input bits and a codeword for input blocks containing the combination. Some codewords include a number of bits having the given bit value that is different than the predetermined target probability distribution, but an average number of bits having the given bit value in the available codewords meets the predetermined target probability distribution. The disclosed methods result in more available codewords and a lower rate loss than in bit-level distribution matchers with a constant modulus, while achieving similar shaping.

Abstract: Systems and methods for constellation shaping using low rate loss bit-level distribution matchers include receiving blocks of input bits and, for each input block of a predetermined size, assigning a respective codeword of a predetermined output block size. The number of bits of a given bit value in the codeword is dependent on a predetermined target probability distribution. A one-to-one mapping exists between each possible combination of input bits and a codeword for input blocks containing the combination. Some codewords include a number of bits having the given bit value that is different than the predetermined target probability distribution, but an average number of bits having the given bit value in the available codewords meets the predetermined target probability distribution. The disclosed methods result in more available codewords and a lower rate loss than in bit-level distribution matchers with a constant modulus, while achieving similar shaping.

Abstract: An optical transmitter for probabilistic shaping and symbol rate optimization includes one or more matcher elements, each configured to assign respective probabilities to symbols represented in received binary data dependent on a target probability distribution and to output a respective shaped bit sequence. The optical transmitter further includes a single systematic error correction encoder configured to add parity bits collectively across the shaped bit sequences and to output a combined shaped bit sequence including data representing the shaped bit sequences and the added parity bits. The optical transmitter also includes multiple mapping elements, each configured to generate a respective codeword for each symbol represented in a portion of the combined shaped bit sequence, a serial-to-parallel converter to provide portions of the combined shaped bit sequence to the mapping elements, and a multiplexer to combine binary data representing the codewords for transmission using subcarrier multiplexing.

Abstract: Systems and methods for setting fiber input power for an optical transmission path may include determining an initial modulation format representing a uniform distribution QAM format, the initial modulation format associated with a first fiber input power and a first spectral efficiency, configuring optical transponders to apply probabilistic shaping to the initial modulation format when transmitting traffic over the optical transmission path, the traffic including probabilistically shaped signals with a second spectral efficiency, determining, dependent on the second spectral efficiency, a second fiber input power, and configuring optical amplifiers along the optical transmission path to transmit the traffic comprising the probabilistically shaped signals over the optical transmission path using the second fiber input power.

Abstract: A system and method for probabilistic shaping of an eight-dimensional super-symbol in optical transport networks, including receiving binary data to be transmitted as an optical signal; mapping at least a portion of the binary data to symbols of a M-QAM constellation; generating a first four-dimensional symbol of the M-QAM constellation for a first symbol period, including applying probabilistic shaping to the first four-dimensional symbol; generating a second four-dimensional symbol of the M-QAM constellation for a second symbol period, the second symbol period consecutive to the first symbol period, wherein the first and the second four-dimensional symbols have i) an equal symbol energy and ii) a one-to-one relationship; and time interleaving the first symbol period and the second symbol period to generate an eight-dimensional super-symbol.

Abstract: Systems and methods for constellation shaping of QAM modulation formats in an optical transport network may include selecting a target information rate for an optical transmission path, determining a measure of fiber nonlinearity for transmission media on the path, and selecting, dependent on the measure of fiber nonlinearity, one of multiple supported shaping parameter pairs, each specifying a respective shaping strength level and a respective error correction strength level. A network management system may configure optical transponders to apply probabilistic shaping to a QAM modulation format in accordance with the selected shaping parameter pair. A shaping parameter pair specifying a high shaping strength level and a low error correction strength level may be selected when the measure of fiber nonlinearity is high. A shaping parameter pair specifying a low shaping strength level and a high error correction strength level may be selected when the measure of fiber nonlinearity is low.

Abstract: Systems and methods for reducing variance in reach of wavelength division multiplexed (WDM) channels in optical transport networks may include selecting, for each channel assigned to a respective wavelength, an initial modulation format and an initial distribution of constellation points in the complex plane, determining a target reach for all WDM channels that is achievable by higher wavelength channels but not by shorter wavelength channels, and applying one or more reach extension techniques to at least one shorter wavelength channel but not to the higher wavelength channels. The reach extension techniques may include probabilistic constellation shaping, symbol rate optimized subcarrier multiplexing, or a combination of the two. Transponders may be configurable to transmit or receive traffic over the WDM channels with or without implementing the reach extension techniques, as applicable.

Abstract: Systems and methods for constellation shaping of M-QAM modulation formats in optical transport networks may receive binary data to be transmitted as an optical signal and partition symbols of an M-QAM constellation in the complex plane into two non-overlapping subsets of symbols, The systems and methods may include assigning respective probabilities to each symbol in the first subset of symbols dependent on a target probability distribution for the first subset, mapping at least a portion of the received binary data to the symbols in the first subset, including generating a respective codeword for each symbol in the first subset, in a first symbol period, providing data representing the respective codewords mapped to the symbols in the first subset to an optical modulator for transmission, and refraining from providing any data representing codewords mapped to the symbols in the second subset to the optical modulator until a second symbol period.

Abstract: A disclosed method for extending reach in an adaptive optical network may include selecting, for an optical channel having a given target distance and a given maximum data rate, the modulation format having the highest spectral efficiency among modulation formats supported in the adaptive optical network that are suitable for optical channels having the given target distance and the given maximum data rate, determining a symbol rate for the optical channel dependent on characteristics of transmission media for the optical channel, determining a number of subcarriers for the optical channel corresponding to the determined symbol rate, and activating subcarrier multiplexing (SCM) for the optical channel. Activating SCM may include configuring transponders to transmit or receive the traffic in the optical channel using the selected modulation format and the determined number of subcarriers. The method may be implemented by a network management system of the optical network.

Abstract: A disclosed method for configuring an optical network includes determining that a measure of performance for a first optical path is approaching a safe threshold and designating the first optical path as at risk for performance degradation due to additional traffic. The method also includes, in response to adding a new optical path, calculating a system margin for the first optical path representing a difference between an OSNR delivered on the first optical path and a required OSNR for error-free operation on the first optical path, determining that the system margin is insufficient to meet an applicable performance level, modifying an operating parameter of a transmitter or receiver of the first optical path and refraining from calculating a system margin for a second optical path that is not designated as at risk for performance degradation. The method may be implemented by a network management system of the optical network.

Abstract: Methods and systems are provided for wavelength shift elimination during spectral inversion in optical networks. The method includes receiving an input optical signal, and generating a combined optical signal by combining, by Bragg scattering, the input optical signal having an input wavelength with a first pump signal having a first wavelength. The method further includes converting the combined optical signal into an output optical signal, by phase-conjugation, using a second pump signal having a second wavelength. The output optical signal has the same wavelength as the input optical signal.

Abstract: Methods and systems are provided for wavelength shift elimination during spectral inversion in optical networks. The method includes receiving an input optical signal, and generating a combined optical signal by combining, by Bragg scattering, the input optical signal having an input wavelength with a first pump signal having a first wavelength. The method further includes converting the combined optical signal into an output optical signal, by phase-conjugation, using a second pump signal having a second wavelength. The output optical signal has the same wavelength as the input optical signal.

Abstract: In one embodiment, a method for receiving optical signals includes receiving a first set of one or more signals and a second set of one or more signals, determining a block length used to process the first set of signals, and processing the first set of signals using the block length. The first set of signals and the second set of signals are separated by a guard band. The block length is based upon the width of the guard band.

Abstract: In accordance with embodiments of the present disclosure, a method for compensation of noise in an optical device is provided. The method may include calculating noise present in an optical carrier signal. The method may also include generating quadrature amplitude modulation input signals, the quadrature amplitude modulation input signals each including a term for compensation of the noise based on the calculated noise. The method may further include modulating the optical carrier signal to generate a modulated optical signal based on quadrature amplitude modulation input signals.