Aspects of the present disclosure describe systems, methods and structures for optical fiber nonlinearity compensation using neural networks that advantageously employ machine learning (ML) algorithms for nonlinearity compensation (NLC) that advantageously provide a system-agnostic model independent of link parameters, and yet still achieve a similar or better performance at a lower complexity as compared with prior-art methods. Systems, methods, and structures according to aspects of the present disclosure include a data-driven model using the neural network (NN) to predict received signal nonlinearity without prior knowledge of the link parameters. Operationally, the NN is provided with intra-channel cross-phase modulation (IXPM) and intra-channel four-wave mixing (IFWM) triplets that advantageously provide a more direct pathway to underlying nonlinear interactions.

In some implementations, an optical receiver includes a polarization beam splitter configured to split a reception signal into a first polarization reception signal and a second polarization reception signal, a first demultiplexing component configured to demultiplex the first polarization reception signal into a first optical signal and a second optical signal associated with a first polarization, a second demultiplexing component configured to demultiplex the second polarization reception signal into a third optical signal and a fourth optical signal associated with a second polarization, a first demodulation component configured to mix the first optical signal and the third optical signal with a first local oscillator signal to demodulate the first optical signal and the third optical signal, and a second demodulation component configured to mix the second optical signal and the fourth optical signal with a second local oscillator signal to demodulate the second optical signal and the fourth optical signal.

In some implementations, an optical receiver includes a demultiplexing component configured to demultiplex a reception signal into a first reception signal and a second reception signal, a first polarization beam splitter configured to split the first reception signal into a first optical signal associated with a first polarization and a second optical signal associated with a second polarization, a second polarization beam splitter configured to split the second reception signal into a third optical signal associated with the first polarization and a fourth optical signal associated with the second polarization, a first demodulation component configured to mix the first optical signal and the second optical signal with a first local oscillator signal, and a second demodulation component configured to mix the third optical signal and the fourth optical signal with a second local oscillator signal.

An optical transmission system, in which an optical transmission apparatus and an optical reception apparatus are provided, includes a coefficient determination unit configured to optimize, based on a reception signal received by the optical reception apparatus, a coefficient to be used to compensate for deterioration according to characteristics of each device configuring a transmission path between the optical transmission apparatus and the optical reception apparatus, and a device characteristic estimation unit configured to estimate the characteristics of each device by using the optimized coefficient.

An all-optical signal processor includes one or more input ports configured to receive one or more optical signal channels, a first nonlinear optical processor configured to receive an input signal from the input port and having one or more sections of a first nonlinear medium, an optical phase conjugator optically configured to receive the output signal of the first nonlinear optical processor, a second nonlinear optical processor configured to receive an output signal from the optical phase conjugator and having one or more sections of a second nonlinear medium, and one or more output ports configured to receive the output signal from the second nonlinear optical processor. Variations of the all-optical signal processor can include a single nonlinear optical processor through which an output of the optical phase conjugator co-propagates or counter-propagates with the input signal.

Embodiments of this disclosure provide an impairment monitoring apparatus, impairment monitoring and compensating system and method. As a parameter of a impairment of a receiver end and/or a parameter of an impairment of a transmitter end is/are determined according to a preset period or a preset condition to perform compensation or calibration, complexity of calculation and power consumption of the system may be efficiently lowered. And as the parameter of the impairment of the receiver end and the parameter of the impairment of the transmitter end are not changed rapidly, determining these parameters according to the preset period or the preset condition to perform compensation or calibration will not affect an effect of the compensation or calibration, thereby ensuring a performance of the system.

A method and device is provided for reducing optical transmission impairments, particularly nonlinear effects, of at least one link Said method comprising the following steps: extracting a phase information () from an optical signal (120) received via that at least one link, determining a nonlinear coefficient (), associated with the at least one link, based on the phase information (), applying a control mechanism (202) using the nonlinear coefficient (). Furthermore, a communication system is suggested comprising said device.

Systems and methods are provided for adaptive equalization, for example for use with coherent optical reception. The equalizer has a loop for updating taps of an adaptive linear filter forming part of the equalizer. In the loop, an error calculator calculates an error, a gradient calculator calculates a gradient of the error or filtered error. One or more gradient filters are used to filter the gradient, and the filtered gradient is used to update the taps of the adaptive linear filter. A reduction in self oscillation in the equalizer is achieved by separating the frequencies with channel features that change with time and scaling them up to speed up convergence of the equalizer.

There is provided a monitor device for monitoring a transmission line including a memory, and a processor coupled to the memory and configured to compensate for a portion of chromatic dispersion on electric signals indicating an electric field component of an optical signal, compensate for deterioration due to a nonlinear optical effect on the electric signals on which the portion of chromatic dispersion is compensated, compensate for a remaining chromatic dispersion except for the portion of chromatic dispersion on the electric signals on which the deterioration due to the nonlinear optical effect is compensated, evaluate quality of the electric signals on which remaining chromatic dispersion except for the portion of chromatic dispersion are compensated, and acquire a first compensation amount of the portion of chromatic dispersion and a second compensation amount of the deterioration due to the nonlinear optical effect, when the evaluated quality satisfies a predetermined condition.

A signal processing circuit includes: a processor configured to adjust phases of reception samples which is supplied at a supply interval, according to a phase adjustment amount; and a processing circuit including a finite impulse response (FIR) filter with taps and configured to process, by the FIR filter, each of the reception samples and output output symbols at an output interval different from the supply interval, the processor is configured to: derive initial values of tap coefficients for the respective taps; and derive the phase adjustment amount such that a center of centroids of the tap coefficients at respective output time points of the output symbols coincides with a center of a number of taps of the FIR filter, the tap coefficients at respective output time points of the output symbols being set according to a deviation between the supply interval and the output interval and the initial values.