A nonlinear compensation method and apparatus and a system in a multicarrier optical communication system where the method includes: determining a coefficient of a linear filter in nonlinear compensation according to an end-to-end channel linear response of the system; determining taps of a nonlinear compensation filter needing to be opened and coefficients of the taps according to a hardware compensation ability of the system and the coefficient of the linear filter; and compensating for a nonlinear damage of the system by using the selected coefficients of the nonlinear compensation filter. With the method, apparatus or the system provided by this application, very good compensation performance may be achieved in a range of power consumption of the multicarrier optical communication system by only opening and using few taps of the compensation filter.

A nonlinear compensation method and apparatus and a system in a multicarrier optical communication system where the method includes: determining a coefficient of a linear filter in nonlinear compensation according to an end-to-end channel linear response of the system; determining taps of a nonlinear compensation filter needing to be opened and coefficients of the taps according to a hardware compensation ability of the system and the coefficient of the linear filter; and compensating for a nonlinear damage of the system by using the selected coefficients of the nonlinear compensation filter. With the method, apparatus or the system provided by this application, very good compensation performance may be achieved in a range of power consumption of the multicarrier optical communication system by only opening and using few taps of the compensation filter.

The invention relates to the aspects of implementation of compensation, or equalization devices aimed at nonlinear impairment mitigation in fiber optic communication systems by means of including the spatially varying dispersive characteristics, or parameters of the underlying waveguides and their potential performance improvement from utilization of those parameters.

The invention relates to the aspects of implementation of compensation, or equalization devices aimed at nonlinear impairment mitigation in fiber optic communication systems by means of including the spatially varying dispersive characteristics, or parameters of the underlying waveguides and their potential performance improvement from utilization of those parameters.

To provide a method capable of easily compensating waveform distortion due to a non-linear effect caused by a complicated electric circuit, and a device for implementing the method. Provided are a method capable of effectively compensating signal degradation such as waveform distortion due to a nonlinear effect caused by an optical fiber that is an optical transfer path using an optical phase conjugate signal pair at the time of optical up-conversion or down-conversion, and a device capable of implementing the method. This emission device 25 includes an optical modulator 11, a signal source 13, an optical fiber 15, a multiplexing unit 17, a multiplexing local signal source 19, an optical detector 12, and a transmission antenna 23.

A method (1200) of transmitting digital information via a nonlinear optical channel (722), comprises receiving (1202) data (702) comprising at least a portion of the digital information. A plurality of frequency domain symbols is generated (1204) from the data, and each symbol is assigned to one of a predetermined plural number of frequency sub-bands. Each sub-band may be processed separately (1206) to reduce a peak-to-average power ratio (PAPR) of a transmitted optical signal. The optical signal (12) is then generated (1208) comprising the plural number of sub-bands, and transmitted via the nonlinear optical channel (722). The plural number of frequency sub-bands is predetermined so as to reduce nonlinear optical distortion of the optical signal within the nonlinear optical channel relative to a corresponding single frequency band signal. A corresponding information-receiving method, a transmitter apparatus and a receiver apparatus are also disclosed.

A method (1200) of transmitting digital information via a nonlinear optical channel (722), comprises receiving (1202) data (702) comprising at least a portion of the digital information. A plurality of frequency domain symbols is generated (1204) from the data, and each symbol is assigned to one of a predetermined plural number of frequency sub-bands. Each sub-band may be processed separately (1206) to reduce a peak-to-average power ratio (PAPR) of a transmitted optical signal. The optical signal (12) is then generated (1208) comprising the plural number of sub-bands, and transmitted via the nonlinear optical channel (722). The plural number of frequency sub-bands is predetermined so as to reduce nonlinear optical distortion of the optical signal within the nonlinear optical channel relative to a corresponding single frequency band signal. A corresponding information-receiving method, a transmitter apparatus and a receiver apparatus are also disclosed.

In order to provide a configuration for suppressing deterioration in the transmission quality of a signal light due to a nonlinear phenomenon in an optical fiber, a polarization dispersion adder is provided with: a polarization rotation unit which, with respect to each pulse of signal light generated by modulating a light carrier, rotates and outputs the polarization of the pulse during a period from a pulse rise start time (T0) to a pulse fall completion time (T1); and a delay addition unit which adds a delay of an amount corresponding to the rotation amount of the polarization added by the polarization rotation unit to the pulse outputted from the polarization rotation unit.

In order to provide a configuration for suppressing deterioration in the transmission quality of a signal light due to a nonlinear phenomenon in an optical fiber, a polarization dispersion adder is provided with: a polarization rotation unit which, with respect to each pulse of signal light generated by modulating a light carrier, rotates and outputs the polarization of the pulse during a period from a pulse rise start time (T0) to a pulse fall completion time (T1); and a delay addition unit which adds a delay of an amount corresponding to the rotation amount of the polarization added by the polarization rotation unit to the pulse outputted from the polarization rotation unit.

A crosstalk estimation system includes: a light source unit that generates a polarization-multiplexed light, which is a polarized light having multiplexed polarizations, of each wavelength in a sideband of a modulated signal and emits the polarization-multiplexed light of each wavelength; a multiplexer that multiplexes the modulated signal with the polarization-multiplexed light for each core, which is associated with one of the wavelengths; a transmission line that transmits the modulated signal multiplexed with the polarization-multiplexed light of each wavelength through a different core; a separation unit that separates the polarization-multiplexed light from the modulated signal multiplexed with the polarization-multiplexed light for each core; a measurement unit that generates light intensity data on the polarization-multiplexed light of each wavelength; and an estimation unit that estimates a crosstalk between the cores based on a difference in light intensity between the polarization-multiplexed light of the wavelengths.