CN105471507A - Nonlinear compensation method and device - Google Patents

Abstract

The present invention provides a nonlinear compensation method and device to solve the problem of large computing amount of the existing algorithm for calculating polarization multiplexing-wavelength division multiplexing system nonlinear damage compensation. The method comprises a step of dividing the distance of a channel into S sections with the same length according to a step length value, wherein the step length value is larger than the dispersion length value of a transmission signal and is smaller than the nonlinear length value of the transmission signal, and S is an integer larger than 1, a step of obtaining the dispersion compensation factor of each channel, the walk-off factor among different channels and the correlation coefficient between the adjacent transmission signals in each channel, a step of carrying out dispersion compensation on each section in the S sections in each channel according to the dispersion compensation factor, and a step of carrying out nonlinear compensation on each section in the S sections of each channel according to the correlation coefficient and the walk-off factor. According to the nonlinear compensation method and device, while the nonlinear damage compensation is calculated, the influence of the dispersion and walk-off effect are considered, the step length can be far larger than the dispersion length, and the number of calculation steps and the total amount of computation are effectively reduced.

Description

A kind of non-linear compensation method and device

Technical field

The present invention relates to coherent optical communication technical field, refer to a kind of non-linear compensation method and device especially.

Background technology

Coherent optical communication system is generally considered a kind of more effective communication system because of its high sensitivity.In recent years, digital signal processing technique is applied in coherent optical communication system.Utilize DSP, convenient cheap polarization and phase place management can be realized in electrical domain.The more important thing is, can compensate signal impairment in electrical domain.In current nonlinear impairments backoff algorithm, digital back-propagating DBP method is proved to be the most promising, but the amount of calculation that DBP method needs is very large, is difficult to bear.The key realizing nonlinear compensation is at present that design effectively can reduce amount of calculation but affect the New Algorithm of compensation effect not too much.

DBP method is based on the non-linear Schrodinger equation NLSE of solution along back-propagating.NLSE is nonlinear partial differential equation, usually needs Numerical Methods Solve.At present, step Fourier method (SSFM) solves the most effective method of NLSE.SSFM is by supposition in transmitting procedure, and light field is often by a bit of distance (step), and dispersion and nonlinear effect can act on successively respectively, thus obtains an approximation.Like this, the amount of calculation needed for DBP calculating and step-length are inversely proportional to.In order to reduce amount of calculation, larger step-length should be selected as far as possible.The minimum value of---dispersion length, non-linear length, walk from length and four wave mixing FWM length---but in order to ensure computational accuracy, the step-length selected in Practical Calculation generally should be less than four feature physical length.

Current nonlinear impairments backoff algorithm comprises three kinds of backoff algorithms, and the first algorithm material calculation is subject to away the restriction from length, and amount of calculation is huge, is difficult to bear; Second algorithm adopt explicit algorithm walk from mode counted the impact of walk-off effect, but material calculation is still subject to the restriction of dispersion length; Before and after the third algorithm utilizes, the association of interchannel has counted the impact on intrachannel nonlinear effect of effect of dispersion, but this algorithm can not nonlinear interaction between compensate for channel, can not be used for wdm system.

Summary of the invention

The object of the present invention is to provide a kind of non-linear compensation method and device, the problem that the algorithm amount of calculation in order to solve existing calculating palarization multiplexing-wavelength-division multiplex system nonlinear impairments compensation is large.

To achieve these goals, the invention provides a kind of non-linear compensation method, be applied to palarization multiplexing-wavelength-division multiplex system, described palarization multiplexing-wavelength-division multiplex system comprises multiple channel for signal transmission, comprising:

According to step value, the distance of each described channel is divided into the S section of equal length, wherein, described step value is greater than the dispersion length value of described signal transmission and is less than the non-linear length value of described signal transmission, S be greater than 1 integer;

Obtain the incidence coefficient walked in the factor and each described channel between adjacent transmission signal between the dispersion compensation factors of each described channel, different channels;

According to described dispersion compensation factors, respectively dispersion compensation is carried out to each section in each described channel S section;

According to described incidence coefficient and described in walk from the factor, respectively nonlinear compensation is carried out to each section in each described channel S section.

Wherein, above-mentioned non-linear compensation method, passes through formula:

H _m(ω,h)＝exp[iβ ₂h(ωmΔω-ω ²/2)]

Obtain the dispersion compensation factors of each described channel; Wherein, m represents m channel, and Δ ω is channel separation, and h is step value, and i represents imaginary number, and ω is angular frequency, β ₂it is abbe number.

Wherein, above-mentioned non-linear compensation method, passes through formula:

$W_{\mathrm{mq}}(\mathrm{\ω},h)=\frac{e^{\mathrm{ah}-{\mathrm{id}}_{{\mathrm{mq}}^{\mathrm{\ωz}}}}-1}{\mathrm{\α}-{\mathrm{id}}_{\mathrm{mq}}\mathrm{\ω}}$

Obtain and walk from the factor between different channels; Wherein, α is loss factor, and h is step value, d _mqrepresent to walk from parameter, d _mq=β ₂(ω _m-ω _q), z represents transmission range, and ω is angular frequency, m and q represents channel designator.

Wherein, by perturbation method or approximating method, obtain the incidence coefficient between adjacent transmission signal in each described channel.

Wherein, described according to described dispersion compensation factors, the step of each section in each described channel S section being carried out to dispersion compensation is specially:

Pass through formula:

${\hat{E}}_{(x,y)m}(t,z+h)=F^{-1}\left\{F\right[{\hat{E}}_{(x,y)m}(t,z)\left]H_m(\mathrm{\ω},h)\right\}$

Dispersion compensation is carried out to each section in each described channel S section; Wherein, x and y represents polarization state, and z represents transmission range, the amplitude at expression time t and transmission range z+h place, the amplitude at expression time t and transmission range z place, H _mrepresent dispersion compensation factors, F represents Fourier transform, F ^-1represent inverse Fourier transform.

Wherein, described according to described incidence coefficient and described in walk from the factor, the step of each section in each described channel S section being carried out respectively to nonlinear compensation comprises:

According to described incidence coefficient, calculate the weighted average of adjacent transmission signal intensity in described channel, obtain the efficient intensity of described channel;

According to described incidence coefficient, walk from the factor and described efficient intensity, obtain the nonlinear factor of described channel;

According to described efficient intensity and described nonlinear factor, nonlinear compensation is carried out to each section in each described channel S section.

Wherein, described according to described incidence coefficient, walk from the factor and described efficient intensity, the step obtaining the nonlinear factor of described channel is specially:

Pass through formula:

${\mathrm{\φ}}_{(x,y)m}(t,z+h)=-\frac{8}{9}\mathrm{\γ}[(P_{\mathrm{xm}}(t,z)+P_{\mathrm{ym}}(t,z))h_{\mathrm{eff}}+F^{-1}\{\underset{\∀q\≠m}{\mathrm{\Σ}}{R}_{(x,y)q}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: Self-phase modulation SPM and Cross-phase Modulation XPM phase shift factor;

Pass through formula:

${\mathrm{\φ}}_m(t,z+h)=-\frac{8}{9}\mathrm{\γ}\left[F^{-1}\right\{\underset{\∀q\≠m}{\mathrm{\Σ}}{{\hat{E}}^{*}}_{\mathrm{yq}}(\mathrm{\ω},z){\hat{E}}_{\mathrm{xq}}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: the relevant XPM factor;

Wherein, γ is non linear coefficient, W _mqrepresent to walk from the factor, m and q represents channel designator;

H _effrepresent effective step value, and h _eff=[exp (α h)-1] α, α are loss factors, and h is step value;

P _xmrepresent the efficient intensity in m channel x direction, P _ymrepresent the efficient intensity in m channel y direction;

E _yq(ω, z) represents the Fourier transform of q channel y direction signal amplitude; E _xq(ω, z) represents the Fourier transform of q channel x direction signal amplitude;

R (ω, z) is R _{(x, y) m}=2P _{(x, y) m}+ P _{(y, x) m}fourier transform;

F ^-1represent inverse Fourier transform.

Wherein, described according to described efficient intensity and described nonlinear factor, the step of each section in each described channel S section being carried out to nonlinear compensation comprises:

Pass through formula:

$E_{\mathrm{xm}}(t,z+h)=E_{\mathrm{xm}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{xm}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{ym}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{ym}}}{Q}_m\sin c\left(\right|Q_m\left|\right);$

$E_{\mathrm{ym}}(t,z+h)=E_{\mathrm{ym}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{ym}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{xm}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{xm}}}{Q^{*}}_m\sin c\left(\right|Q_m\left|\right);$

Nonlinear compensation is carried out to each section in each described channel S section;

Wherein, E _xm(t, z+h) represents the amplitude of time t and distance z+h place x-polarisation state;

E _ym(t, z+h) represents the amplitude of time t and distance z+h place y-polarisation state;

E _xm(t, z) represents the amplitude of time t and distance z place x-polarisation state;

E _ym(t, z) represents the amplitude of time t and distance z place y-polarisation state;

φ _mrepresent SPM and the XPM phase shift factor of m channel;

Q _mrepresent the relevant XPM factor of m channel.

Embodiments of the invention additionally provide a kind of nonlinear compensating device, comprising:

Divide module, for the distance of each described channel being divided into according to step value the S section of equal length, wherein, described step value is greater than the dispersion length value of described signal transmission and is less than the non-linear length value of described signal transmission, S be greater than 1 integer;

Acquisition module, for obtaining the incidence coefficient walked in the factor and each described channel between adjacent transmission signal between the dispersion compensation factors of each described channel, different channels;

Dispersion compensation module, for according to described dispersion compensation factors, carries out dispersion compensation respectively to each section in each described channel S section;

Nonlinearity compensation module, for according to described incidence coefficient and described in walk from the factor, respectively nonlinear compensation is carried out to each section in each described channel S section.

Wherein, above-mentioned nonlinear compensating device, described acquisition module comprises:

First acquisition module, for passing through formula H _m(ω, h)=exp [i β ₂h (ω m Δ ω-ω ²/ 2) dispersion compensation factors of each described channel] is obtained; Wherein, m represents m channel, and Δ ω is channel separation, and h is step value, and i represents imaginary number, and ω is angular frequency, β ₂it is abbe number;

Second acquisition module, for passing through formula:

$W_{\mathrm{mq}}(\mathrm{\ω},h)=\frac{e^{\mathrm{ah}-{\mathrm{id}}_{{\mathrm{mq}}^{\mathrm{\ωz}}}}-1}{\mathrm{\α}-{\mathrm{id}}_{\mathrm{mq}}\mathrm{\ω}}$

Obtain and walk from the factor between different channels; Wherein, α is loss factor, and h is step value, d _mqrepresent to walk from parameter, d _mq=β ₂(ω _m-ω _q), z represents transmission range, and ω is angular frequency, m and q represents channel designator;

3rd acquisition module, for by perturbation method or approximating method, obtains the incidence coefficient between adjacent transmission signal in each described channel.

Wherein, described dispersion compensation module is especially by formula:

${\hat{E}}_{(x,y)m}(t,z+h)=F^{-1}\left\{F\right[{\hat{E}}_{(x,y)m}(t,z)\left]H_m(\mathrm{\ω},h)\right\}$

Carry out dispersion compensation to each section in each described channel S section, wherein, x and y represents polarization state, and z represents transmission range, the amplitude at expression time t and distance z+h place, the amplitude at expression time t and distance z place, H _mrepresent dispersion compensation factors, F represents Fourier transform, F ^-1represent inverse Fourier transform.

Wherein, described nonlinearity compensation module comprises:

Computing unit, for according to described incidence coefficient, calculates the weighted average of adjacent transmission signal intensity in described channel, obtains the efficient intensity of described channel;

Acquiring unit, for according to described incidence coefficient, walk from the factor and described efficient intensity, obtain the nonlinear factor of described channel;

Compensating unit, for according to described efficient intensity and described nonlinear factor, carries out nonlinear compensation to each section in each described channel S section.

Wherein, described acquiring unit passes through formula:

${\mathrm{\φ}}_{(x,y)m}(t,z+h)=-\frac{8}{9}\mathrm{\γ}[(P_{\mathrm{xm}}(t,z)+P_{\mathrm{ym}}(t,z))h_{\mathrm{eff}}+F^{-1}\{\underset{\∀q\≠m}{\mathrm{\Σ}}{R}_{(x,y)q}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: Self-phase modulation SPM and Cross-phase Modulation XPM phase shift factor;

Described acquiring unit passes through formula:

${\mathrm{\φ}}_m(t,z+h)=-\frac{8}{9}\mathrm{\γ}\left[F^{-1}\right\{\underset{\∀q\≠m}{\mathrm{\Σ}}{{\hat{E}}^{*}}_{\mathrm{yq}}(\mathrm{\ω},z){\hat{E}}_{\mathrm{xq}}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: the relevant XPM factor;

Wherein, γ is non linear coefficient, W _mqrepresent to walk from the factor, m and q represents channel designator;

H _effrepresent effective step value, and h _eff=[exp (α h)-1] α, α are loss factors, and h is step value;

P _xmrepresent the efficient intensity in m channel x direction, P _ymrepresent the efficient intensity in m channel y direction;

E _yq(ω, z) represents the Fourier transform of q channel y direction signal amplitude; E _xq(ω, z) represents the Fourier transform of q channel x direction signal amplitude;

R (ω, z) is R _{(x, y) m}=2P _{(x, y) m}+ P _{(y, x) m}fourier transform;

F ^-1represent inverse Fourier transform.

Wherein, described compensating unit passes through formula:

$E_{\mathrm{xm}}(t,z+h)=E_{\mathrm{xm}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{xm}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{ym}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{ym}}}{Q}_m\sin c\left(\right|Q_m\left|\right);$

$E_{\mathrm{ym}}(t,z+h)=E_{\mathrm{ym}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{ym}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{xm}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{xm}}}{Q^{*}}_m\sin c\left(\right|Q_m\left|\right);$

Nonlinear compensation is carried out to each section in each described channel S section;

Wherein, E _xm(t, z+h) represents the amplitude of time t and distance z+h place x-polarisation state;

E _ym(t, z+h) represents the amplitude of time t and distance z+h place y-polarisation state;

E _xm(t, z) represents the amplitude of time t and distance z place x-polarisation state;

E _ym(t, z) represents the amplitude of time t and distance z place y-polarisation state;

φ _mrepresent SPM and the XPM phase shift factor of m channel;

Q _mrepresent the relevant XPM factor of m channel.

The embodiment of the present invention has following beneficial effect:

The non-linear compensation method of the embodiment of the present invention, adopts the impact of explicit consideration walk-off effect and utilizes the association of adjacent signals to count the impact of effect of dispersion, making step value far can exceed dispersion length, effectively reduces and calculates step number and calculate total amount.

Accompanying drawing explanation

Fig. 1 represents the workflow diagram of the embodiment of the present invention;

What Fig. 2 represented the embodiment of the present invention realizes schematic diagram;

Fig. 3 represents the contrast simulation design sketch of the embodiment of the present invention and prior art;

Fig. 4 represents the structured flowchart of the embodiment of the present invention.

Embodiment

For making the technical problem to be solved in the present invention, technical scheme and advantage clearly, be described in detail below in conjunction with specific embodiment and accompanying drawing.

Embodiments provide a kind of non-linear compensation method and device, solve the problem that the algorithm amount of calculation of existing calculating palarization multiplexing-wavelength-division multiplex system nonlinear impairments compensation is large.

The non-linear compensation method of the embodiment of the present invention, is applied to palarization multiplexing-wavelength-division multiplex system, and described palarization multiplexing-wavelength-division multiplex system comprises multiple channel for signal transmission, as shown in Figure 1, comprising:

Step S10: the S section according to step value, the distance of each channel being divided into equal length, wherein, described step value is greater than the dispersion length value of signal transmission and is less than the non-linear length value of signal transmission, S be greater than 1 integer.

Step S20: obtain the incidence coefficient walked in the factor and each channel between adjacent transmission signal between the dispersion compensation factors of each channel, different channels.

In a particular embodiment of the present invention, formula is passed through:

H _m(ω,h)＝exp[iβ ₂h(ωmΔω-ω ²/2)]

Obtain the dispersion compensation factors of each channel, wherein, m represents m channel, and Δ ω is channel separation, and h is step value, and i represents imaginary number, and ω is angular frequency, β ₂it is abbe number;

In a particular embodiment of the present invention, formula is passed through:

$W_{\mathrm{mq}}(\mathrm{\ω},h)=\frac{e^{\mathrm{ah}-{\mathrm{id}}_{{\mathrm{mq}}^{\mathrm{\ωz}}}}-1}{\mathrm{\α}-{\mathrm{id}}_{\mathrm{mq}}\mathrm{\ω}}$

Obtain and walk from the factor between different channels, wherein, α is loss factor, and h is step value, d _mqrepresent to walk from parameter, d _mq=β ₂(ω _m-ω _q), z represents transmission range, and ω is angular frequency, m and q represents channel designator;

In a particular embodiment of the present invention, by perturbation method or approximating method, obtain the incidence coefficient between adjacent transmission signal in each described channel.

Step S30: according to dispersion compensation factors, carries out dispersion compensation respectively to each section in each channel S section.

In a particular embodiment of the present invention, concrete, pass through formula:

${\hat{E}}_{(x,y)m}(t,z+h)=F^{-1}\left\{F\right[{\hat{E}}_{(x,y)m}(t,z)\left]H_m(\mathrm{\ω},h)\right\}$

Dispersion compensation is carried out to each section in each channel S section; Wherein, x and y represents polarization state, and z represents transmission range, the amplitude at expression time t and transmission range z+h place, the amplitude at expression time t and transmission range z place, H _mrepresent dispersion compensation factors, F represents Fourier transform, F ^-1represent inverse Fourier transform.

Step S40: according to incidence coefficient and walk from the factor, carries out nonlinear compensation respectively to each section in each described channel S section.

In a particular embodiment of the present invention, according to incidence coefficient, calculate the weighted average of adjacent transmission signal intensity in channel, obtain the efficient intensity of channel;

According to incidence coefficient, walk from the factor and efficient intensity, obtain the nonlinear factor of channel, wherein, nonlinear factor comprises: Self-phase modulation SPM and Cross-phase Modulation XPM phase shift factor and the relevant XPM factor, concrete, passes through formula:

${\mathrm{\φ}}_{(x,y)m}(t,z+h)=-\frac{8}{9}\mathrm{\γ}[(P_{\mathrm{xm}}(t,z)+P_{\mathrm{ym}}(t,z))h_{\mathrm{eff}}+F^{-1}\{\underset{\∀q\≠m}{\mathrm{\Σ}}{R}_{(x,y)q}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Be obtained from phase-modulation SPM and Cross-phase Modulation XPM phase shift factor;

Pass through formula:

${\mathrm{\φ}}_m(t,z+h)=-\frac{8}{9}\mathrm{\γ}\left[F^{-1}\right\{\underset{\∀q\≠m}{\mathrm{\Σ}}{{\hat{E}}^{*}}_{\mathrm{yq}}(\mathrm{\ω},z){\hat{E}}_{\mathrm{xq}}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the relevant XPM factor;

Wherein, γ is non linear coefficient, W _mqrepresent to walk from the factor, m and q represents channel designator;

H _effrepresent effective step value, and h _eff=[exp (α h)-1] α, α are loss factors, and h is step value;

P _xmrepresent the efficient intensity in m channel x direction, P _ymrepresent the efficient intensity in m channel y direction;

E _yq(ω, z) represents the Fourier transform of q channel y direction signal amplitude; E _xq(ω, z) represents the Fourier transform of q channel x direction signal amplitude;

R (ω, z) is R _{(x, y) m}=2P _{(x, y) m}+ P _{(y, x) m}fourier transform;

F ^-1represent inverse Fourier transform.

In a particular embodiment of the present invention, according to efficient intensity and described nonlinear factor, nonlinear compensation is carried out to each section in each channel S section, concrete, pass through formula:

$E_{\mathrm{xm}}(t,z+h)=E_{\mathrm{xm}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{xm}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{ym}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{ym}}}{Q}_m\sin c\left(\right|Q_m\left|\right);$

$E_{\mathrm{ym}}(t,z+h)=E_{\mathrm{ym}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{ym}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{xm}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{xm}}}{Q^{*}}_m\sin c\left(\right|Q_m\left|\right);$

Nonlinear compensation is carried out to each section in each channel S section;

Wherein, E _xm(t, z+h) represents the amplitude of time t and distance z+h place x-polarisation state;

E _ym(t, z+h) represents the amplitude of time t and distance z+h place y-polarisation state;

E _xm(t, z) represents the amplitude of time t and distance z place x-polarisation state;

E _ym(t, z) represents the amplitude of time t and distance z place y-polarisation state;

φ _mrepresent SPM and the XPM phase shift factor of m channel;

Q _mrepresent the relevant XPM factor of m channel.

The non-linear compensation method of the embodiment of the present invention, obtains the nonlinear phase of associated effect further by the efficient intensity of channel; Obtained the nonlinear phase of walk-off effect by nonlinear factor further, then utilize above-mentioned formula to carry out nonlinear compensation to each section in channel S section according to the nonlinear phase of associated effect and the nonlinear phase of walk-off effect.

The non-linear compensation method of the embodiment of the present invention, adopts the impact of explicit consideration walk-off effect, utilizes the incidence relation between adjacent signals to count the impact of effect of dispersion simultaneously, makes step value far exceed dispersion length, effectively reduces calculating step number and total amount of calculation.

Illustrate the specific implementation process of the embodiment of the present invention below.

As shown in Figure 2, first according to step value, the distance of each described channel is divided into the S section of equal length by division module, wherein, the concrete numerical value of step value is weighed according to compensation effect and the amount of calculation; Being obtained respectively by above-mentioned formula by acquisition module walks from the factor, simultaneously by the incidence coefficient in perturbation method or each channel of approximating method between adjacent transmission signal between the dispersion compensation factors of each channel, different channels; Dispersion compensation module carries out dispersion compensation to a section in each channel S section; Computing unit, according to incidence coefficient, calculates the weighted average of adjacent transmission signal intensity in channel, obtains the efficient intensity of each channel; Acquiring unit according to incidence coefficient, walk from the factor and efficient intensity, obtain nonlinear factor; Compensating unit, according to efficient intensity and nonlinear factor, carries out nonlinear compensation to a section in each S section; Judge whether each section in each channel S section all completes above-mentioned dispersion compensation and nonlinear compensation, if the determination result is YES, then terminate compensation calculation, if judged result is no, the part then continued not compensating in each channel S section carries out dispersion compensation and nonlinear compensation, until each section in each channel S section has all carried out dispersion compensation and nonlinear compensation.

The non-linear compensation method of the embodiment of the present invention as shown in Figure 3, is the simulated effect of PDM-WDM system under nonlinear compensation, wherein, the 6 channel PDM-16QAM Propagation Simulation data used are obtained by VPI software, and emulation key parameter is: symbol rate 30GBd, and abbe number is 17ps/nm, non linear coefficient VPI gives tacit consent to, frequency shift (FS) 0.5GHz, laser linewidth 100kHz, launched power+1dBm, span 80km, transmission range 800km.In figure, step number refers to the step number of each span.Find out thus, the step number needed for the embodiment of the present invention is minimum, and Effect value (Q) is best.

The non-linear compensation method of the embodiment of the present invention, respectively dispersion compensation and nonlinear compensation are carried out to each section in each channel S section, because the present invention take into account the impact of dispersion and walk-off effect simultaneously, make step value far exceed dispersion length, effectively reduce and calculate step number and the amount of calculation.

The embodiment of the present invention additionally provides a kind of nonlinear compensating device, as shown in Figure 4, comprising:

Divide module, for the distance of each described channel being divided into according to step value the S section of equal length, wherein, described step value between the dispersion length and non-linear length of described signal transmission, S be greater than 1 integer;

Acquisition module, for obtaining the incidence coefficient walked in the factor and each described channel between adjacent transmission signal between the dispersion compensation factors of each described channel, different channels;

Dispersion compensation module, for according to described dispersion compensation factors, carries out dispersion compensation respectively to each section in each described channel S section;

Nonlinearity compensation module, for according to described incidence coefficient and described in walk from the factor, respectively nonlinear compensation is carried out to each section in each described channel S section.

The nonlinear compensating device of the embodiment of the present invention, described acquisition module comprises:

First acquisition module, for passing through formula H _m(ω, h)=exp [i β ₂h (ω m Δ ω-ω ²/ 2) dispersion compensation factors of each described channel] is obtained; Wherein, m represents m channel, and Δ ω is channel separation, and h is step value, and i represents imaginary number, and ω is angular frequency, β ₂it is abbe number;

Second acquisition module, for passing through formula:

$W_{\mathrm{mq}}(\mathrm{\ω},h)=\frac{e^{\mathrm{ah}-{\mathrm{id}}_{{\mathrm{mq}}^{\mathrm{\ωz}}}}-1}{\mathrm{\α}-{\mathrm{id}}_{\mathrm{mq}}\mathrm{\ω}}$

Obtain and walk from the factor between different channels; Wherein, α is loss factor, and h is step value, d _mqrepresent to walk from parameter, d _mq=β ₂(ω _m-ω _q), z represents transmission range, and ω is angular frequency, m and q represents channel designator;

3rd acquisition module, for by perturbation method or approximating method, obtains the incidence coefficient between adjacent transmission signal in each described channel.

In the nonlinear compensating device of the embodiment of the present invention, described dispersion compensation module is especially by formula:

${\hat{E}}_{(x,y)m}(t,z+h)=F^{-1}\left\{F\right[{\hat{E}}_{(x,y)m}(t,z)\left]H_m(\mathrm{\ω},h)\right\}$

Carry out dispersion compensation to each section in each described channel S section, wherein, x and y represents polarization state, and z represents transmission range, the amplitude at expression time t and distance z+h place, the amplitude at expression time t and distance z place, H _mrepresent that dispersion compensation factors F represents Fourier transform, F ^-1represent inverse Fourier transform.

In the nonlinear compensating device of the embodiment of the present invention, described nonlinearity compensation module comprises:

Computing unit, for according to described incidence coefficient, calculates the weighted average of adjacent transmission signal intensity in described channel, obtains the efficient intensity of described channel;

Acquiring unit, for according to described incidence coefficient, walk from the factor and described efficient intensity, obtain the nonlinear factor of described channel;

Compensating unit, for according to described efficient intensity and described nonlinear factor, carries out nonlinear compensation to each section in each described channel S section.

In the nonlinear compensating device of the embodiment of the present invention, described acquiring unit passes through formula:

${\mathrm{\φ}}_{(x,y)m}(t,z+h)=-\frac{8}{9}\mathrm{\γ}[(P_{\mathrm{xm}}(t,z)+P_{\mathrm{ym}}(t,z))h_{\mathrm{eff}}+F^{-1}\{\underset{\∀q\≠m}{\mathrm{\Σ}}{R}_{(x,y)q}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: Self-phase modulation SPM and Cross-phase Modulation XPM phase shift factor;

Described acquiring unit passes through formula:

${\mathrm{\φ}}_m(t,z+h)=-\frac{8}{9}\mathrm{\γ}\left[F^{-1}\right\{\underset{\∀q\≠m}{\mathrm{\Σ}}{{\hat{E}}^{*}}_{\mathrm{yq}}(\mathrm{\ω},z){\hat{E}}_{\mathrm{xq}}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: the relevant XPM factor;

Wherein, γ is non linear coefficient, W _mqrepresent to walk from the factor, m and q represents channel designator;

H _effrepresent effective step value, and h _eff=[exp (α h)-1] α, α are loss factors, and h is step value;

P _xmrepresent the efficient intensity in m channel x direction, P _ymrepresent the efficient intensity in m channel y direction;

E _yq(ω, z) represents the Fourier transform of q channel y direction signal amplitude; E _xq(ω, z) represents the Fourier transform of q channel x direction signal amplitude;

R (ω, z) is R _{(x, y) m}=2P _{(x, y) m}+ P _{(y, x) m}fourier transform;

F ^-1represent inverse Fourier transform.

In the nonlinear compensating device of the embodiment of the present invention, described compensating unit passes through formula:

$E_{\mathrm{xm}}(t,z+h)=E_{\mathrm{xm}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{xm}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{ym}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{ym}}}{Q}_m\sin c\left(\right|Q_m\left|\right);$

$E_{\mathrm{ym}}(t,z+h)=E_{\mathrm{ym}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{ym}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{xm}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{xm}}}{Q^{*}}_m\sin c\left(\right|Q_m\left|\right);$

Nonlinear compensation is carried out to each section in each described channel S section;

Wherein, E _xm(t, z+h) represents the amplitude of time t and distance z+h place x-polarisation state;

E _ym(t, z+h) represents the amplitude of time t and distance z+h place y-polarisation state;

E _xm(t, z) represents the amplitude of time t and distance z place x-polarisation state;

E _ym(t, z) represents the amplitude of time t and distance z place y-polarisation state;

φ _mrepresent SPM and the XPM phase shift factor of m channel;

Q _mrepresent the relevant XPM factor of m channel.

It should be noted that, this device is the device corresponding with said method embodiment, and in said method embodiment, all implementations are all applicable in the embodiment of this device, also can reach identical technique effect.

The non-linear compensation method of the embodiment of the present invention and device, take into account the impact of dispersion and walk-off effect simultaneously when carrying out nonlinear compensation, step value far can exceed dispersion length, effectively reduces calculating step number and the amount of calculation.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (14)

1. a non-linear compensation method, is applied to palarization multiplexing-wavelength-division multiplex system, and described palarization multiplexing-wavelength-division multiplex system comprises multiple channel for signal transmission, it is characterized in that, comprising:

According to step value, the distance of each described channel is divided into the S section of equal length, wherein, described step value is greater than the dispersion length value of described signal transmission and is less than the non-linear length value of described signal transmission, S be greater than 1 integer;

Obtain the incidence coefficient walked in the factor and each described channel between adjacent transmission signal between the dispersion compensation factors of each described channel, different channels;

According to described dispersion compensation factors, respectively dispersion compensation is carried out to each section in each described channel S section;

According to described incidence coefficient and described in walk from the factor, respectively nonlinear compensation is carried out to each section in each described channel S section.

2. non-linear compensation method according to claim 1, is characterized in that, passes through formula:

H _m(ω,h)＝exp[iβ ₂h(ωmΔω-ω ²/2)]

Obtain the dispersion compensation factors of each described channel; Wherein, m represents m channel, and Δ ω is channel separation, and h is step value, and i represents imaginary number, and ω is angular frequency, β ₂it is abbe number.

3. non-linear compensation method according to claim 1, is characterized in that, passes through formula:

$W_{\mathrm{mq}}(\mathrm{\ω},h)=\frac{e^{\mathrm{ah}-{\mathrm{id}}_{{\mathrm{mq}}^{\mathrm{\ωz}}}}-1}{\mathrm{\α}-{\mathrm{id}}_{\mathrm{mq}}\mathrm{\ω}}$

Obtain and walk from the factor between different channels; Wherein, α is loss factor, and h is step value, d _mqrepresent to walk from parameter, d _mq=β ₂(ω _m-ω _q), z represents transmission range, and ω is angular frequency, m and q represents channel designator.

4. non-linear compensation method according to claim 1, is characterized in that, by perturbation method or approximating method, obtains the incidence coefficient between adjacent transmission signal in each described channel.

5. non-linear compensation method according to claim 1, is characterized in that, described according to described dispersion compensation factors, and the step of each section in each described channel S section being carried out to dispersion compensation is specially:

Pass through formula:

${\hat{E}}_{(x,y)m}(t,z+h)=F^{-1}\left\{F\right[{\hat{E}}_{(x,y)m}(t,z)\left]H_m(\mathrm{\ω},h)\right\}$

Dispersion compensation is carried out to each section in each described channel S section; Wherein, x and y represents polarization state, and z represents transmission range, the amplitude at expression time t and transmission range z+h place, the amplitude at expression time t and transmission range z place, H _mrepresent dispersion compensation factors, F represents Fourier transform, F ^-1represent inverse Fourier transform.

6. non-linear compensation method according to claim 1, is characterized in that, described according to described incidence coefficient and described in walk from the factor, the step of each section in each described channel S section being carried out respectively to nonlinear compensation comprises:

According to described incidence coefficient, calculate the weighted average of adjacent transmission signal intensity in described channel, obtain the efficient intensity of described channel;

According to described incidence coefficient, walk from the factor and described efficient intensity, obtain the nonlinear factor of described channel;

According to described efficient intensity and described nonlinear factor, nonlinear compensation is carried out to each section in each described channel S section.

7. non-linear compensation method according to claim 6, is characterized in that, described according to described incidence coefficient, walk from the factor and described efficient intensity, the step obtaining the nonlinear factor of described channel is specially:

Pass through formula:

${\mathrm{\φ}}_{(x,y)m}(t,z+h)=-\frac{8}{9}\mathrm{\γ}[(P_{\mathrm{xm}}(t,z)+P_{\mathrm{ym}}(t,z))h_{\mathrm{eff}}+F^{-1}\{\underset{\∀q\≠m}{\mathrm{\Σ}}{R}_{(x,y)q}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: Self-phase modulation SPM and Cross-phase Modulation XPM phase shift factor;

Pass through formula:

${\mathrm{\φ}}_m(t,z+h)=-\frac{8}{9}\mathrm{\γ}\left[F^{-1}\right\{\underset{\∀q\≠m}{\mathrm{\Σ}}{{\hat{E}}^{*}}_{\mathrm{yq}}(\mathrm{\ω},z){\hat{E}}_{\mathrm{xq}}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: the relevant XPM factor;

Wherein, γ is non linear coefficient, W _mqrepresent to walk from the factor, m and q represents channel designator;

H _effrepresent effective step value, and h _eff=[exp (α h)-1] α, α are loss factors, and h is step value;

P _xmrepresent the efficient intensity in m channel x direction, P _ymrepresent the efficient intensity in m channel y direction;

E _yq(ω, z) represents the Fourier transform of q channel y direction signal amplitude; E _xq(ω, z) represents the Fourier transform of q channel x direction signal amplitude;

R (ω, z) is R _{(x, y) m}=2P _{(x, y) m}+ P _{(y, x) m}fourier transform;

F ^-1represent inverse Fourier transform.

8. non-linear compensation method according to claim 7, is characterized in that, described according to described efficient intensity and described nonlinear factor, and the step of each section in each described channel S section being carried out to nonlinear compensation comprises:

Pass through formula:

$E_{\mathrm{xm}}(t,z+h)=E_{\mathrm{xm}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{xm}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{ym}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{ym}}}{Q}_m\sin c\left(\right|Q_m\left|\right);$

$E_{\mathrm{ym}}(t,z+h)=E_{\mathrm{ym}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{ym}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{xm}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{xm}}}{Q^{*}}_m\sin c\left(\right|Q_m\left|\right);$

Nonlinear compensation is carried out to each section in each described channel S section;

Wherein, E _xm(t, z+h) represents the amplitude of time t and distance z+h place x-polarisation state;

E _ym(t, z+h) represents the amplitude of time t and distance z+h place y-polarisation state;

E _xm(t, z) represents the amplitude of time t and distance z place x-polarisation state;

E _ym(t, z) represents the amplitude of time t and distance z place y-polarisation state;

φ _mrepresent SPM and the XPM phase shift factor of m channel;

Q _mrepresent the relevant XPM factor of m channel.

9. a nonlinear compensating device, is applied to palarization multiplexing-wavelength-division multiplex system, and described palarization multiplexing-wavelength-division multiplex system comprises multiple channel for signal transmission, it is characterized in that, comprising:

Divide module, for the distance of each described channel being divided into according to step value the S section of equal length, wherein, described step value is greater than the dispersion length value of described signal transmission and is less than the non-linear length value of described signal, S be greater than 1 integer;

Acquisition module, for obtaining the incidence coefficient walked in the factor and each described channel between adjacent transmission signal between the dispersion compensation factors of each described channel, different channels;

Dispersion compensation module, for according to described dispersion compensation factors, carries out dispersion compensation respectively to each section in each described channel S section;

Nonlinearity compensation module, for according to described incidence coefficient and described in walk from the factor, respectively nonlinear compensation is carried out to each section in each described channel S section.

10. nonlinear compensating device according to claim 9, is characterized in that, described acquisition module comprises:

First acquisition module, for passing through formula H _m(ω, h)=exp [i β ₂h (ω m Δ ω-ω ²/ 2) dispersion compensation factors of each described channel] is obtained; Wherein, m represents m channel, and Δ ω is channel separation, and h is step value, and i represents imaginary number, and ω is angular frequency, β ₂it is abbe number;

Second acquisition module, for passing through formula:

$W_{\mathrm{mq}}(\mathrm{\ω},h)=\frac{e^{\mathrm{ah}-{\mathrm{id}}_{{\mathrm{mq}}^{\mathrm{\ωz}}}}-1}{\mathrm{\α}-{\mathrm{id}}_{\mathrm{mq}}\mathrm{\ω}}$

Obtain and walk from the factor between different channels; Wherein, α is loss factor, and h is step value, d _mqrepresent to walk from parameter, d _mq=β ₂(ω _m-ω _q), z represents transmission range, and ω is angular frequency, m and q represents channel designator;

3rd acquisition module, for by perturbation method or approximating method, obtains the incidence coefficient between adjacent transmission signal in each described channel.

11. nonlinear compensating devices according to claim 9, is characterized in that, described dispersion compensation module is especially by formula:

${\hat{E}}_{(x,y)m}(t,z+h)=F^{-1}\left\{F\right[{\hat{E}}_{(x,y)m}(t,z)\left]H_m(\mathrm{\ω},h)\right\}$

Carry out dispersion compensation to each section in each described channel S section, wherein, x and y represents polarization state, and z represents transmission range, the amplitude at expression time t and distance z+h place, the amplitude at expression time t and distance z place, H _mrepresent dispersion compensation factors, F represents Fourier transform, F ^-1represent inverse Fourier transform.

12. nonlinear compensating devices according to claim 9, is characterized in that, described nonlinearity compensation module comprises:

Computing unit, for according to described incidence coefficient, calculates the weighted average of adjacent transmission signal intensity in described channel, obtains the efficient intensity of described channel;

Acquiring unit, for according to described incidence coefficient, walk from the factor and described efficient intensity, obtain the nonlinear factor of described channel;

Compensating unit, for according to described efficient intensity and described nonlinear factor, carries out nonlinear compensation to each section in each described channel S section.

13. non-linear compensation methods according to claim 12, is characterized in that, described acquiring unit passes through formula:

${\mathrm{\φ}}_{(x,y)m}(t,z+h)=-\frac{8}{9}\mathrm{\γ}[(P_{\mathrm{xm}}(t,z)+P_{\mathrm{ym}}(t,z))h_{\mathrm{eff}}+F^{-1}\{\underset{\∀q\≠m}{\mathrm{\Σ}}{R}_{(x,y)q}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: Self-phase modulation SPM and Cross-phase Modulation XPM phase shift factor;

Described acquiring unit passes through formula:

${\mathrm{\φ}}_m(t,z+h)=-\frac{8}{9}\mathrm{\γ}\left[F^{-1}\right\{\underset{\∀q\≠m}{\mathrm{\Σ}}{{\hat{E}}^{*}}_{\mathrm{yq}}(\mathrm{\ω},z){\hat{E}}_{\mathrm{xq}}(\mathrm{\ω},z)W_{\mathrm{mq}}(\mathrm{\ω},h)\left\}\right]$

Obtain the nonlinear factor of described channel, described nonlinear factor comprises: the relevant XPM factor;

Wherein, γ is non linear coefficient, W _mqrepresent to walk from the factor, m and q represents channel designator;

H _effrepresent effective step value, and h _eff=[exp (α h)-1] α, α are loss factors, and h is step value;

P _xmrepresent the efficient intensity in m channel x direction, P _ymrepresent the efficient intensity in m channel y direction;

E _yq(ω, z) represents the Fourier transform of q channel y direction signal amplitude; E _xq(ω, z) represents the Fourier transform of q channel x direction signal amplitude;

R (ω, z) is R _{(x, y) m}=2P _{(x, y) m}+ P _{(y, x) m}fourier transform;

F ^-1represent inverse Fourier transform.

14. nonlinear compensating devices according to claim 13, is characterized in that, described compensating unit passes through formula:

$E_{\mathrm{xm}}(t,z+h)=E_{\mathrm{xm}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{xm}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{ym}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{ym}}}{Q}_m\sin c\left(\right|Q_m\left|\right);$

$E_{\mathrm{ym}}(t,z+h)=E_{\mathrm{ym}}(t,z)e^{i{\mathrm{\φ}}_{\mathrm{ym}}}\cos \left(\right|Q_m\left|\right)-{\mathrm{iE}}_{\mathrm{xm}}(t,z)e^{{\mathrm{i\φ}}_{\mathrm{xm}}}{Q^{*}}_m\sin c\left(\right|Q_m\left|\right);$

Nonlinear compensation is carried out to each section in each described channel S section;

Wherein, E _xm(t, z+h) represents the amplitude of time t and distance z+h place x-polarisation state;

E _ym(t, z+h) represents the amplitude of time t and distance z+h place y-polarisation state;

E _xm(t, z) represents the amplitude of time t and distance z place x-polarisation state; E _ym(t, z) represents the amplitude of time t and distance z place y-polarisation state; φ _mrepresent SPM and the XPM phase shift factor of m channel; Q _mrepresent the relevant XPM factor of m channel.