Abstract: Embodiments of this disclosure provide an apparatus and method for estimating polarization skew. The method includes: acquiring a plurality of coefficients of an adaptive equalizer of a receiving device; the plurality of coefficients of the adaptive equalizer include at least polarization skew of a transmitting device and polarization skew of the receiving device; and calculating the polarization skew of the transmitting device and the polarization skew of the receiving device according to the plurality of coefficients of the adaptive equalizer.

Abstract: 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.

Abstract: An estimation apparatus for IQ imbalance of an optical transmitter, a compensation apparatus for IQ imbalance of an optical transmitter and electronic equipment; wherein, estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.

Abstract: A method and apparatus of fiber nonlinear noise monitoring and an optical receiver is provided. The method includes: acquiring a training set including at least two received signal samples obtained after a transmitting signal passes different simulation transmission scenarios, calculating amplitude noise feature values after a digital signal processing, calculating statistics values of fiber nonlinear noises, marking the amplitude noise feature values; taking the amplitude noise feature values as input of a noise monitoring model, taking marks to which the amplitude noise feature values correspond as target output, and training the noise monitoring model according to samples in the training set, so as to obtain a trained noise monitoring model, and inputting a plurality of amplitude noise feature values of received signals to be monitored into the trained noise monitoring model, so as to obtain statistics values of fiber nonlinear noises to which the received signals to be monitored correspond.

Abstract: A method and apparatus estimating direct current bias of an optical modulator and a receiver. The method includes: performing signal processing to obtain a phase noise compensated signal, extracting a receiving signal component based on the phase noise compensated signal, removing the receiving signal component from the phase noise compensated signal, and calculating a received signal power based on the signal with the receiving signal component being removed. The method includes calculating a direct current bias of the optical modulator based on the receiving signal component, the received signal power and a drive signal power of the optical modulator.

Abstract: A bias control apparatus and method of a modulator of an optical transmitter and an optical transmitter, in which by performing mutual interference on driving signals of two Mach-Zehnder modulators constituting the modulator of the optical transmitter, output optical fields of the two Mach-Zehnder modulators are correlated. Hence, an output power signal of the modulator of the optical transmitter contains information on phase bias. Thus, the phase bias may be controlled by using the output power signal, sensitivity of the bias control may be efficiently improved, and various types of modulation formats may be applied.

Abstract: 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.

Abstract: Embodiments of this disclosure provide a compensation apparatus for an offset drift, a received signal recovery apparatus and a receiver, in which estimation and compensation of an offset drift are directly performed at a receiver end, with no need of extra provision of an offset control circuit at a transmitter end, so that the system is simple in structure, applicable to various modulation formats, wide in applicability, and is able to meet demands for high-order modulation formats. And furthermore, by equalizing a received signal and performing phase recovery on a frequency difference and phase noises, information on offset points of a modulator of the transmitter end may be accurately separated, thereby accurately compensating for the offset drift of the modulator of the transmitter end.

Abstract: A method and apparatus estimating direct current bias of an optical modulator and a receiver. The method includes: performing signal processing to obtain a phase noise compensated signal, extracting a receiving signal component based on the phase noise compensated signal, removing the receiving signal component from the phase noise compensated signal, and calculating a received signal power based on the signal with the receiving signal component being removed. The method includes calculating a direct current bias of the optical modulator based on the receiving signal component, the received signal power and a drive signal power of the optical modulator.

Abstract: Embodiments of this disclosure provide a bias control apparatus and method of a modulator of an optical transmitter and an optical transmitter. By obtaining respective output power signals of a first Mach-Zehnder modulator and a second Mach-Zehnder modulator constituting the modulator of the optical transmitter, information on a phase bias may be extracted according to the two output power signals and an overall output power signal of the modulator of the optical transmitter, so as to control the phase bias by using the information, thereby efficiently improving a sensitivity of the control of the bias, and being applicable to various types of modulation formats.

Abstract: An estimation apparatus for IQ imbalance of an optical transmitter, a compensation apparatus for IQ imbalance of an optical transmitter and electronic equipment; wherein, estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.

Abstract: An inter-channel linear crosstalk estimation method and apparatus and a communication system are disclosed.

Abstract: Provided is an apparatus for measuring a filtering characteristic, a pre-equalizer and an optical communication equipment where the apparatus includes: a first processing unit configured to determine a filtering characteristic of a receiving end, or determine a joint response of a filtering characteristic of a transmitting end and the filtering characteristic of the receiving end, in a spectrum of a receiving signal obtained after a first measurement signal and a second measurement signal pass through respective filtering modules, according to a nonoverlapped spectral part of the first measurement signal and the second measurement signal. The filtering modules through which the first measurement signal passes include a transmitting end filtering module and a receiving end filtering module, the filtering module through which the second measurement signal passes include the receiving end filtering module.

Abstract: A method and apparatus for measuring a filtering characteristic, pre-equalizer and communication equipment. The apparatus for measuring a filtering characteristic includes: a first processing unit configured to determine a filtering characteristic of a receiving end according to an amplitude of a receiving signal obtained after a measurement signal passes through a transmitting end filtering module and a receiving end filtering module at provided different frequency offsets of a transmitting laser of a transmitting end and a local laser of the receiving end.

Abstract: Embodiments of this disclosure provide a bias control apparatus and method of a modulator of an optical transmitter and an optical transmitter. By obtaining respective output power signals of a first Mach-Zehnder modulator and a second Mach-Zehnder modulator constituting the modulator of the optical transmitter, information on a phase bias may be extracted according to the two output power signals and an overall output power signal of the modulator of the optical transmitter, so as to control the phase bias by using the information, thereby efficiently improving a sensitivity of the control of the bias, and being applicable to various types of modulation formats.

Abstract: A method and apparatus for measuring a filtering characteristic, pre-equalizer and communication equipment. The method includes: obtaining a receiving signal after two measurement signals of different spectral ranges pass through different filtering modules and are received at the same time at a receiving end; and determining a part of a filtering characteristic of a receiving end and a part of a joint response according to a nonoverlapped spectral part of the two signals in the spectrum of the receiving signal.

Abstract: A bias control apparatus and method of a modulator of an optical transmitter and an optical transmitter, in which by performing mutual interference on driving signals of two Mach-Zehnder modulators constituting the modulator of the optical transmitter, output optical fields of the two Mach-Zehnder modulators are correlated. Hence, an output power signal of the modulator of the optical transmitter contains information on phase bias. Thus, the phase bias may be controlled by using the output power signal, sensitivity of the bias control may be efficiently improved, and various types of modulation formats may be applied.

Abstract: A method and apparatus for measuring a filtering characteristic, pre-equalizer and communication equipment. Wherein, the apparatus for measuring a filtering characteristic includes: a first measuring unit configured to measure multiple pieces of first average power of multiple first signals obtained after multiple first transmission signals pass through a transmitting end filtering module and are modulated, frequencies of the multiple first transmission signals being different; and a first processing unit configured to determine a filtering characteristic of the transmitting end according to the first average power, amplitudes of the first transmission signals and a first predefined correspondence relationship between average power of signals after passing through the transmitting end filtering module and being modulated and a product of amplitudes of the signals and the filtering characteristic of the transmitting end.

Abstract: Embodiments of this disclosure provide a compensation apparatus for an offset drift, a received signal recovery apparatus and a receiver, in which estimation and compensation of an offset drift are directly performed at a receiver end, with no need of extra provision of an offset control circuit at a transmitter end, so that the system is simple in structure, applicable to various modulation formats, wide in applicability, and is able to meet demands for high-order modulation formats. And furthermore, by equalizing a received signal and performing phase recovery on a frequency difference and phase noises, information on offset points of a modulator of the transmitter end may be accurately separated, thereby accurately compensating for the offset drift of the modulator of the transmitter end.

Abstract: A compensation apparatus and method for inter-channel nonlinear damage are disclosed where the apparatus includes: an iteration parameter determining unit configured to determine an iteration step of cross-phase modulation damage compensation performed in each channel in a multichannel optical fiber transmission link; an estimating unit configured to divide an optical fiber transmission link in each iteration step of each channel into one or more optical fiber segments, and perform cross-phase modulation damage estimation at a position in each optical fiber segment where the nonlinear damage is maximal; and a first compensating unit configured to perform cross-phase modulation damage compensation according to the result of the cross-phase modulation damage estimation.