CN101145847B - Preferential choice method for wave length scheme of G.653 optical fiber WDM system - Google Patents

Abstract

The invention discloses a wavelength proposal optimization method in a G.653 optical fiber WDM system, relating to a working wavelength optimization method in a G.653 optical fiber wavelength division multiplexing (WDM) system. The system can efficiently reduce the FWM crosstalk of the wavelength proposal optimization method in the G.653 optical fiber WDM system. The method in the invention comprises the following steps: step 1, the system parameter of the G.653 optical fiber C band is set; step 2, the wavelength of the C band is optimized through calculation. The invention sets the system parameter and then calculates to get the wavelength proposal by utilizing the related parameters, thereby being able to select multiple wavelength number. The invention is able to simulate the actual optical parameters during parameters setting so as to improve the adaptability of the wavelength in the actual engineering.

Description

G.653 the method for optimizing of optical fiber WDM system wave length scheme

Technical field

The present invention relates to the method for optimizing of operation wavelength in the optical fibre wavelength-division multiplex system (WDM) G.653, relate in particular to by optimized choice C-band wavelength, system can effectively reduce the method for optimizing of the G.653 optical fiber WDM system wave length scheme that FWM crosstalks.

Background technology

The Transmission Fibers of optical fiber communication has experienced from the multimode to the single mode, from G.652-〉G.653-〉G.655 development course.Though it is G.652 the optical fiber loss is little, big in the chromatic dispersion of 1550nm window; Though G.653 optical fiber is little in the chromatic dispersion of 1550nm window, in wdm system, be easy to generate four wave mixing (FWM) effect, cause serious transmission impairment.At present, a large amount of G.653 optical fiber has been laid by countries such as Japan, Latin America, and how the transmission wdm system becomes a difficult problem that presses for solution on optical fiber G.653.

G.653 optical fiber WDM system has two kinds of solutions usually: 1. work in L-band; 2. use the C-band wavelength selectively.Utilize the bigger optical fiber dispersion of L-band to reduce FWM and crosstalk, but the optical device cost of L-band is high at no distant date.By optimized choice C-band wavelength, system can effectively reduce FWM and crosstalk.

The wavelength selection algorithm mainly contains cycle scheduling algorithm not, the disclosed patent CN1489304A of Huawei Tech Co., Ltd " system of selection of dispersion shifted optical fiber C-band wavelength-division signal transmission wavelength ", and the employing cycle is scheduling algorithm not, has realized 12 ripple Scheme Selection.This method at first will need the dense wave division multipurpose signal packets transmitted, each sets of signals is arranged in the wavestrip away from dispersion shifted optical fiber chromatic dispersion zero-dispersion wavelength, when being provided with, make the channel of each signal in above-mentioned each sets of signals be complete unequal interval and distribute, determine every group then in the wavelength of each signaling channel.

The Theoretical Calculation of four-wave mixing power can be with reference to the paper " Fiber Four-WaveMixing in Multi-Amplifier Systems with Nonuniform Chromatic Dispersion " of Kyo Inoue, (source: JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL.13, NO.1, JANUARY1995, pp.88～93.) Theoretical Calculation and result of the test coincide better.When frequency is respectively f _p, f _q, f _rLight signal, power is respectively P _p, P _q, P _r, when transmitting together on optical fiber G.653, the frequency that the FWM effect produces is f _FWM=f _p+ f _q-f _r, through after a plurality of sections of striding, the Power Theory formula of crosstalking that the FWM effect produces is:

$P_{\mathrm{FWM}}=\frac{1024{\mathrm{\π}}^6}{n_0^4{\mathrm{\λ}}^2{c}^2}{\left(\mathrm{D\χ}\right)}^2\frac{P_p{P}_q{P}_r}{A_{\mathrm{eff}}^2}{e}^{-\mathrm{\αL}}\mathrm{\η}$

Wherein D is a degeneracy factor, and x is a non-linear susceptibility, A _EffBe optical fiber effective area, the FWM efficiency eta is a following formula:

$\mathrm{\η}={|\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{e}^{i\underset{k=1}{\overset{m-1}{\mathrm{\Σ}}}\mathrm{\Δ}{\mathrm{\Φ}}^{\left(k\right)}}\×\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\{e^{\underset{j=1}{\overset{n-1}{\mathrm{\Σ}}}(-\mathrm{\α}+\mathrm{i\Δ}{\mathrm{\β}}^{\left(\mathrm{mj}\right)})L_0}\×\frac{1-e^{(-\mathrm{\α}+\mathrm{i\Δ}{\mathrm{\β}}^{\left(\mathrm{mn}\right)})L_0}}{\mathrm{\α}-\mathrm{i\Δ}{\mathrm{\β}}^{\left(\mathrm{mn}\right)}}\}|}^2$

Need consider the phase place overlaying influence, the section phase place of m section is $\mathrm{\Δ}{\mathrm{\Φ}}^{\left(m\right)}=\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{\Δ}{\mathrm{\β}}^{\left(\mathrm{mn}\right)}{L}_0,$

The off resonance amount Δ β of the n segment optical fiber of the m section of striding ^(mn)For:

$\mathrm{\Δ}{\mathrm{\β}}^{\left(\mathrm{mn}\right)}=-\frac{\mathrm{\π}{\mathrm{\λ}}^4}{c^2}S[(f_p-f_0^{\left(\mathrm{mn}\right)})+(f_q-f_0^{\left(\mathrm{mn}\right)})]\×(f_p-f_r)\×(f_q-f_r)$

ITU-T suggestion G.653 (12/2003) " Characteristics of a dispersion-shiftedsingle-mode optical fibre and cable " lining has provided G.653 requirement of optical fiber dispersion characteristic index and canonical parameter, but, index is very loose, sees the following form:

Wavelength (minimum value) λ min	1525nm
		Wavelength (maximum) λ max	1575nm
Abbe number (maximum) Dmax	3.5ps/(nm×km)?
		Zero-dispersion wavelength (minimum value) λ Omin	1500nm?
Zero-dispersion wavelength (maximum) λ Omax	1600nm?
		Zero-dispersion slop (maximum) SOmax	0.085ps/(nm2×km)?
Zero-dispersion wavelength (representative value) λ Otyp	1550nm?

[0014]?

Zero-dispersion slop (representative value) SOtyp

0.07ps/(nm2×km)?

It should be noted that the system transmissions performance of wave length scheme is relevant with the zero-dispersion wavelength of optical fiber G.653, the centre in zero-dispersion wavelength is in bandwidth range, its performance is poor more.So wave length scheme need be considered the adaptability to different zero-dispersion wavelength system.

Summary of the invention

The technical problem to be solved in the present invention is to realize that wdm system in the G.653 transmission of optical fiber, has proposed a kind of method that can improve the optimized choice C-band wave length scheme of spendable number of wavelengths in the C-band.

The method for optimizing of G.653 optical fiber WDM system wave length scheme of the present invention may further comprise the steps:

The first step is provided with the G.653 system parameters of optical fiber C-band;

Second step is by calculating at C-band optimized choice wavelength.

The system parameters that is provided with in the described first step comprises that single ripple transmitting optical power, system stride hop count, stride segment length, the number of wavelengths of system design and alternative number of wavelengths, the attenuation coefficient of the zero-dispersion wavelength of every segment optical fiber, zero-dispersion slop and optical fiber; The computational methods in described second step are the theories of computation according to four-wave mixing power, by FWM power calculation optimized choice wavelength.This is by relevant system parameters being set, selecting a kind of method of wavelength then by calculation mode.

Described second step comprises step 2.1, presets a plurality of wavelength at C-band; Step 2.2 remains in alternative wavelength at C-band and to select to select the residue wavelength by calculating.Can reduce the time of calculating like this, raise the efficiency.

Described to preset a plurality of wavelength at C-band be to preset according to following principle, avoids the zero-dispersion wavelength zone as far as possible, and sparse with respect to the Wavelength distribution in the zone of optical fiber dispersion maximum near the Wavelength distribution in zero-dispersion wavelength zone.This is a kind of principle that presets wavelength, can directly rule of thumb select a part of wavelength according to this principle.

Select the residue wavelength to comprise 2.21 analysis and judgement steps by calculating in the described step 2.2,, then do not carry out FWM power calculation program, and proceed the wavelength search utility if the wave length scheme of current iteration is identical with historical wave length scheme.Can raise the efficiency like this.

Select the residue wavelength to comprise 2.22 analysis and judgement steps by calculating in the described step 2.2,, then do not carry out FWM power calculation program if uniformly-spaced number of wavelengths is more for the wave length scheme of discovery current iteration.Can raise the efficiency like this.

The method for optimizing of described G.653 optical fiber WDM system wave length scheme also comprised for the 3rd step: the robustness of investigating wave length scheme, be of the influence of system's CHROMATIC DISPERSION IN FIBER OPTICS characteristic variations to systematic function, measurement index is that FWM disturbs minimum, disturb little robustness all right, after repeatedly carrying out the optimized choice in second step, therefrom select the best wave length scheme of robustness, and export this wave length scheme.Can select more excellent wave length scheme like this.

When investigating the robustness of wave length scheme in described the 3rd step, be divided into three kinds of situations:

(1), the zero-dispersion wavelength of optical fiber meets normal distribution, mean value is 1550nm, standard deviation is 3.5nm;

(2), the zero-dispersion wavelength of optical fiber meets normal distribution, mean value is the value of 1545nm, standard deviation is 3.5nm;

(3), the zero-dispersion wavelength of optical fiber meets normal distribution, mean value is the value of 1555nm, standard deviation is 3.5nm;

Every kind of situation is carried out m random parameter, obtains the data of M group FWM power worst-case value, and it is carried out statistical analysis, obtain the mean value and the standard deviation of FWM power worst-case value, with this measurement index as robustness, the mean value of FWM power is big more, illustrates that robustness is poor more.By being divided into three kinds of above-mentioned situations, can investigate the robustness of the scheme under following two kinds of situations; 1. the average zero dispersion wavelength and the zero-dispersion slop of system are fixed, but the zero-dispersion wavelength of every segment optical fiber and zero-dispersion slop change at random; 2. the average zero dispersion wavelength of system changes.

When investigating the robustness of wave length scheme in described the 3rd step,,, no longer investigate situation (2) and situation (3) for saving computing time if think that the wave length scheme that second step obtained before the robustness ratio of situation (1) is poor.Computing time can be saved like this.

System's CHROMATIC DISPERSION IN FIBER OPTICS characteristic variations of described investigation comprises two kinds to the influence of systematic function: 1. the average zero dispersion wavelength and the zero-dispersion slop of system are fixed, but the zero-dispersion wavelength of every segment optical fiber and zero-dispersion slop change at random; 2. the average zero dispersion wavelength of system changes.

Therefore the present invention can select to teach many number of wavelengths owing to by system parameters is set, carries out Calculation Method in the relevant parameter of utilization then and obtain wave length scheme.And when system parameters is set, can simulate the optical fiber parameter of actual engineering, can improve the adaptability of wave length scheme actual engineering.

Description of drawings

Fig. 1 is the flow chart of wave length scheme optimized choice.

Embodiment

G.694.1 the design of wdm system wavelength generally should follow the ITU-T suggestion.In the embodiment with from C-band preferred 16 ripple (C 80 ripples of 50GHz at interval ₈₀ ¹⁶) and preferred 40 ripple (C ₈₀ ⁴⁰) describe for example.

The first step: system parameters is set.

The alternative number of wavelengths of system is 80, and needing the preferred wavelength number is 40.This paper remembers that the wavelength of 192.1THz is a sequence number 1, and 192.15THz is a sequence number 2, and the like, be sequence number 80 until 196.05THz.

Consider that 40 ripple wdm systems can transmit to stride hop count less, and 40 ripples are longer computing time, emulation is set, and to stride hop count be 2, whenever the section of striding 80km.If preferred 16 ripple wdm systems, can design and stride hop count is 8.

Consider the decay of actual engineering optical fiber, design optical fiber attenuation coefficient is 0.20dB/km.The optical fiber attenuation coefficient is more little, and the FWM mixing power of generation is big more.

The 40 wave systems tolerable single ripple transmitting optical power of uniting is less, designs single ripple transmitting optical power and is-5dBm.If preferred 16 ripples, it is 0dBm that transmitting optical power can be set.

The elementary cell length recommendation that the FWM of system calculates is 2km.Also shorter length can be set, still, this can cause prolong computing time.If longer, can reduce the accuracy of simulation model.

The dispersion characteristics of design system are benchmark with the ITU-T suggestion representative value that provides G.653, and consider the deviation in the actual engineering.The dispersion characteristics of system are designed to normal distribution: zero-dispersion wavelength mean value is 1550nm, and standard deviation is 3.5nm; Zero-dispersion slop is 0.07ps/nm, and standard deviation is 0.01ps/nm.

Second step: preset a plurality of wavelength.

The present invention proposes the idea in forbidden band, the forbidden band is positioned near system's optical fiber average zero dispersion wavelength, no longer selects wavelength in the scope of forbidden band.Recommending the scope that is provided with in forbidden band is 193.15THz～193.7THz.(22～33)

The number of wavelengths that recommendation is preset is approximately 1/3～2/3 of total number of wavelengths.Through a large amount of calculating and comparisons, design is preset wavelength and is [1 24579 11 13 14 17 21 34 3,640 43 45 46 48 71 73 74 75 77 78 79 80], have 26 wavelength altogether, as can be seen, long wavelength zone comparatively dense, the short wavelength zone is more sparse, and in the zone near the forbidden band, especially the regional wavelength near 1545nm is more sparse relatively.

The method brief introduction of FWM power calculation: for any one wavelength (f _FWM), three ripples of searching the FWM wavelength that equals this wavelength in all wavelengths make up (f=f _FWM=f _p+ f _q-f _r, and f _p≠ f _r, f _q≠ f _r).Then per three ripples are carried out the FWM power calculation, the FWM power that all three ripples combinations are drawn stacks up, and crosstalks as the FWM power of this wavelength (f).All wavelengths in the system is calculated, obtain the FWM performance number of all wavelengths, with the worst-case value of FWM power maximum as the FWM power of this wave length scheme.Be relatively convenient, the FWM power transfer is the performance number of relative light signal power output when being 0dBm.

The 3rd step: select the residue wavelength.

In the alternative wavelength of residue, select the residue wavelength.Generally, quite from M ball, select the permutation and combination of N ball (M〉N), make the interference minimum of the system that this N ball formed, this is a np complete problem, finding the solution the np complete problem method has multiple, comprise genetic algorithm, particle swarm optimization algorithm and ant group algorithm, and various self-defining searching algorithm.When the complex nature of the problem hour, even can obtain result preferably by enumerating.

Previous step has been selected 26 ripples suddenly, and also remaining 14 ripples need to select, and selectable zone is 49～70, thus Wavelength optimization select combination from

Convert to

Thereby the difficulty of finding the solution np complete problem descends greatly.

Any optimized Algorithm all is to realize that by iterative process iterative solution restrains to optimal solution.Find the solution the efficient of np complete problem algorithm for raising, can adopt some improved search strategies, for example:, then do not carry out FWM power calculation program if 1. the wave length scheme of current iteration is identical with historical wave length scheme; Obviously do not meet expectation if 2. find the wave length scheme of current iteration, for example uniformly-spaced number of wavelengths is more, does not then also carry out FWM power calculation program.Will be because optimized Algorithm obtains the time of a wave length scheme in search procedure much smaller than the time of finishing a FWM power calculation.

The residue wavelength that adopts particle swarm optimization algorithm finally to draw is [50 52 53 56 5,759 60 62 63 65 66 67 69 70].

The 4th step: the robustness of investigating wave length scheme.

The wave length scheme that is drawn by second step and the 3rd step is carried out the robustness of following three kinds of situations and investigate, every kind of situation is carried out m random parameter, recommends m=100:

1. the zero-dispersion wavelength of optical fiber meets normal distribution, and mean value is 1550nm, and standard deviation is 3.5nm;

2. the zero-dispersion wavelength of optical fiber meets normal distribution, and mean value is 1545nm, and standard deviation is 3.5nm;

3. the zero-dispersion wavelength of optical fiber meets normal distribution, and mean value is 1555nm, and standard deviation is 3.5nm.

When as above investigating the robustness of every kind of situation, obtain the data of 100 groups of FWM power worst-case values, it is carried out statistical analysis, obtain the mean value and the standard deviation of FWM power worst-case value, with this measurement index as robustness, the mean value of FWM power is big more, illustrates that robustness is poor more.

It is 1550nm that the optimal wavelength scheme that three steps of front draw is based on zero-dispersion wavelength mean value, wave length scheme performance when zero-dispersion wavelength departs from 1550nm may have certain deterioration, in general, zero-dispersion wavelength mean value is that the system of 1555nm is better than the system that zero-dispersion wavelength is 1545nm.

In robustness is investigated, if think relatively poor at situation robustness 1., for saving computing time, no longer investigate situation 2. with situation 3..

The wave length scheme that robustness is good should be able to adapt to 3 kinds of situations well.After optimized choice repeatedly, therefrom select the best wave length scheme of robustness.The rectangular case of 40 wave-waves that the present invention provides is [1 24 579 11 13 14 17 21 34 36 40 43 45 46 4,850 52 53 56 57 59 60 62 63 65 66 67 69 70 71 7,374 75 77 78 79 80].This wave length scheme for situation 1., the mean value of the FWM worst-case value of robustness is-26.89dBm; For situation 2., the mean value of the FWM worst-case value of robustness is-25.07dBm; For situation 3., the mean value of the FWM worst-case value of robustness is-25.58dBm.

The inventor utilize this method also attempted from C-band at interval preferred 40 ripples 192 ripples of 25GHz ( ).

Compared with prior art, scheme in the embodiment is owing to having taked to preset wavelength, having found the solution technical measures such as np complete problem and assurance robustness, considered actual engineering parameter influence comprehensively, obtained the WDM wave length scheme of series of optimum, realized that wdm system is in the reliable transmission of optical fiber G.653, save the G.653 a large amount of electric relaying of fibre system, improved the technical merit of the wdm system equipment on the optical fiber G.653.

Be the preferred embodiments of the present invention only below, be not limited to the present invention, for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (8)

1.G.653 the method for optimizing of optical fiber WDM system wave length scheme may further comprise the steps:

The first step, G.653 the system parameters of optical fiber C-band is set, described system parameters comprises that single ripple transmitting optical power, system stride hop count, stride segment length, the number of wavelengths of system design and alternative number of wavelengths, the attenuation coefficient of the zero-dispersion wavelength of every segment optical fiber, zero-dispersion slop and optical fiber;

In second step, by calculating at C-band optimized choice wavelength, described computational methods are the theories of computation according to four-wave mixing power, by FWM power calculation optimized choice wavelength.

2. the method for optimizing of G.653 optical fiber WDM system wave length scheme according to claim 1 is characterized in that: described second step comprises step 2.1, presets a plurality of wavelength at C-band; Step 2.2 remains in alternative wavelength by calculating selection residue wavelength at C-band.

3. the method for optimizing of G.653 optical fiber WDM system wave length scheme according to claim 2, it is characterized in that: described to preset a plurality of wavelength at C-band be to preset according to following principle, avoid the zero-dispersion wavelength zone as far as possible, and sparse with respect to the Wavelength distribution in the zone of optical fiber dispersion maximum near the Wavelength distribution in zero-dispersion wavelength zone.

4. the method for optimizing of G.653 optical fiber WDM system wave length scheme according to claim 2, it is characterized in that: select the residue wavelength to comprise 2.21 analysis and judgement steps by calculating in the described step 2.2, if the wave length scheme of current iteration is identical with historical wave length scheme, then do not carry out FWM power calculation program, and proceed the wavelength search utility.

5. the method for optimizing of G.653 optical fiber WDM system wave length scheme according to claim 3, it is characterized in that: the method for optimizing of described G.653 optical fiber WDM system wave length scheme also comprised for the 3rd step: the robustness of investigating wave length scheme, be of the influence of system's CHROMATIC DISPERSION IN FIBER OPTICS characteristic variations to systematic function, measurement index is that FWM disturbs minimum, disturb little robustness all right, after repeatedly carrying out the optimized choice in second step, therefrom select the best wave length scheme of robustness, and export this wave length scheme.

6. the method for optimizing of G.653 optical fiber WDM system wave length scheme according to claim 5 is characterized in that: when investigating the robustness of wave length scheme in described the 3rd step, be divided into three kinds of situations:

(1), the zero-dispersion wavelength of optical fiber meets normal distribution, mean value is 1550nm, standard deviation is 3.5nm;

(2), the zero-dispersion wavelength of optical fiber meets normal distribution, mean value is the value of 1545nm, standard deviation is 3.5nm;

(3), the zero-dispersion wavelength of optical fiber meets normal distribution, mean value is the value of 1555nm, standard deviation is 3.5nm;

Every kind of situation is carried out m random parameter, obtains the data of M group FWM power worst-case value, and it is carried out statistical analysis, obtain the mean value and the standard deviation of FWM power worst-case value, with this measurement index as robustness, the mean value of FWM power is big more, illustrates that robustness is poor more.

7. the method for optimizing of G.653 optical fiber WDM system wave length scheme according to claim 6, it is characterized in that: when investigating the robustness of wave length scheme in described the 3rd step, if think that the wave length scheme that second step obtained before the robustness ratio of situation (1) is poor, for saving computing time, no longer investigate situation (2) and situation (3).

8. the method for optimizing of G.653 optical fiber WDM system wave length scheme according to claim 5, it is characterized in that: system's CHROMATIC DISPERSION IN FIBER OPTICS characteristic variations of described investigation comprises two kinds to the influence of systematic function: 1. the average zero dispersion wavelength and the zero-dispersion slop of system are fixed, but the zero-dispersion wavelength of every segment optical fiber and zero-dispersion slop change at random; 2. the average zero dispersion wavelength of system changes.

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