CN1231009C - Method for restraining self phase modulation (SPM) - Google Patents
Method for restraining self phase modulation (SPM) Download PDFInfo
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- CN1231009C CN1231009C CNB021205574A CN02120557A CN1231009C CN 1231009 C CN1231009 C CN 1231009C CN B021205574 A CNB021205574 A CN B021205574A CN 02120557 A CN02120557 A CN 02120557A CN 1231009 C CN1231009 C CN 1231009C
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Abstract
The present invention relates to a method for restraining self phase modulation (SPM) on the basis of a transmission system which comprises a wave combiner, an optical fiber amplifier, multi-section long-distance optical fiber and an optical relay station which is connected between two sections of adjacent long-distance optical fiber. The present invention is characterized in that in a long-distance cascade transmission process, different dispersion compensation modules can be adopted for dispersedly carrying out dispersion compensation; the shape of an optical pulse is adjusted to make the shape close to the shape of the optical pulse before optical fiber is connected in to the largest degree. The shape of the optical pulse is adjusted by reasonably managing the dispersion distribution of the system. Consequently, the present invention restrains the generation and the influence of an SPM effect, largely reduces frequency spectrum stretching degree because of the generation and the influence of the SPM effect and the deterioration degree of the performance of the system, reduces the requirement of the flatness of the system power of the transmission system, and makes transmission distance sufficiently widened.
Description
Technical field
The present invention relates to the long Distance Transmission technology of light signal, specifically is to be used for the method for a kind of inhibition of long haul transmission system from phase modulated (SPM) video stretching.
Technical background
Decay, chromatic dispersion and nonlinear effect are the key constraints of fiber optic transmission system.Because the application of image intensifer and dispersion compensation module, decay and chromatic dispersion reduce the restriction of system transmissions distance.Some High Speed Systems (as 10G) transmission restricted distance is mainly by nonlinear effect and image intensifer ASE (spontaneous radiation) noise limit.
Fig. 1 is that a kind of typical G655 optical fiber length is apart from cascade transmission system figure.We can see from Fig. 1,32 road 10G signals are synthesized in one road optical fiber through behind the wave multiplexer, passing through EDFA (erbium-doped fiber amplifier) then is amplified to certain luminous power and inputs to later in the long-distance optical fiber and transmit, and carry out an optical relay amplification through 70-100km optical fiber every, and carry out dispersion compensation every one-level or what optical relay as required, be transferred to receiving terminal at last and be divided into 32 road 10G flashlights with channel-splitting filter.In the G655 fiber optic transmission system,, carry out once concentrating dispersion compensation in order to save the generally per as shown in Figure 14 grades of optical relays of cost because the G655 optical fiber dispersion is less.
In order to transmit farther distance, wish to increase the launched power of signal naturally, and signal power increases, and can produce the severe nonlinear effect.In the above SDH of 2.5G grows apart from the cascade transmission system, when surpassing certain thresholding, signal light power produces SPM (from phase modulated) effect later on, and cause optical signal spectrum broadening and system's receptivity to worsen.Wherein SPM (from phase modulated) effect produces to bear at the light pulse rising edge and warbles, produces at trailing edge and just warble, and as shown in Figure 2, causes the optical signal spectrum broadening, and has a strong impact on systematic function by chromatic dispersion.The SPM effect is mainly relevant with light pulse peak power, last lower edge time and last lower edge slope.The light pulse peak power is strong more, upward the lower edge time is long more, upward the lower edge slope is big more, and the SPM effect is strong more.If there is not dispersion interaction, the SPM effect only influences the phase change of light signal, for the not influence of light pulse intensity.But when chromatic dispersion existed, then the phase change that the SPM response can be caused was converted into the Strength Changes of light pulse, thereby influences systematic function, and chromatic dispersion is big more, and this phase noise is strong more to the conversion of intensity noise, and is serious more to system deterioration.
At present, the scheme of head it off mainly is to reduce launched power, by reducing the generation that launched power suppresses the SPM effect, finally improves systematic function.Reduce the launched power scheme and realize simply, but have following defective:
1. for single ripple (or a small amount of a few wave-wave divides multiplexing) long haul transmission system, this technology has been sacrificed transmission range.
For multi-wavelength length apart from the cascade transmission system, this system has improved the requirement to the system power flatness.
Summary of the invention
The objective of the invention is to overcome the problems referred to above that existing transmission system exists, provide a kind of method that is used for the inhibition of long haul transmission system from phase modulated (SPM) video stretching, to improve systematic function.
For achieving the above object, the present invention is achieved in that
Be used for the method for the inhibition of long haul transmission system from phase modulated (SPM), based on the system that contains wave multiplexer, fiber amplifier, the long-distance optical fiber of multistage and be connected the light-repeating ship between the optical fiber of adjacent two segment lengths way, it is characterized in that may further comprise the steps: in growing apart from the cascade transmission course, adopt different dispersion compensation modules, disperse to carry out dispersion compensation.In each grade light-repeating ship, carry out the amplification of dispersion compensation and optical relay, adjust optical pulse shape, reduce the lower edge time on it, increase the power flat region time, make it near going into fine preceding optical pulse shape, to suppress self phase modulation.
A kind of system that is used for long Distance Transmission, comprise long-distance optical fiber and be connected the adjacent two segment lengths light-repeating ship between the optical fiber on the way, light-repeating ship comprises the fiber amplifier and the attenuator of polyphone, it is characterized in that: every grade of light-repeating ship also comprises different dispersion compensation modules, disperses to carry out dispersion compensation.
The inventive method is mainly by reasonably managing the dispersion profile of whole optical fiber telecommunications system, disperse to carry out dispersion compensation, adjust the shape of signal pulse, make it as far as possible near going into fine preceding optical pulse shape, thereby suppress the generation and the influence of SPM effect, reduce the video stretching degree that it causes and the deterioration degree of systematic function greatly, make systematic function reach the requirement of relevant criterion.
The present invention has fully expanded the transmission range of single ripple (or a small amount of a few wave-wave divides multiplexing) long haul transmission system, has reduced the requirement of multi-wavelength length apart from cascade transmission system system power flatness, and system cost is reduced.
The present invention tests through emulation, simulation, and the application test of actual transmissions system, and is through practice, reliably feasible.
Description of drawings
Fig. 1 is that a kind of typical optical fiber length is apart from cascade transmission system structure chart;
Fig. 2 is Gaussian function and the waveform of high-order Gaussian function and the SPM effect of warbling of generation thereof;
Fig. 3 influences figure for chromatic dispersion to optical pulse shape;
Fig. 4 is that optical fiber length of the present invention is apart from cascade transmission system structure chart;
Fig. 5 is centralized compensation dispersion profile figure;
Fig. 6 disperses dispersion profile figure for the present invention.
Embodiment
Further specify below in conjunction with accompanying drawing.
Traditional optical fiber length shown in Figure 1 is as indicated above apart from the cascade transmission system, repeats no more herein.
Fig. 2 is Gaussian function and the waveform of high-order Gaussian function and the SPM effect of warbling of generation thereof.Can know that from Fig. 2 the shape of light pulse has a strong impact on the intensity of SPM effect, and dispersion interaction is the main cause that causes pulse shape to change.And SPM effect itself directly do not influence system's receptivity, but work by chromatic dispersion.That is to say that chromatic dispersion influences phase noise intensity that the SPM effect produces and the phase noise conversion strength to intensity noise simultaneously, thereby effective scientific management is carried out in chromatic dispersion is crucial.Science dispersion management of the present invention is mainly reflected on the dispersion compensation module, promptly selects different dispersion compensation modules at the various parameters of chromatic dispersion, transmission range and the optical signal pulses of transmission link glazing pricker, is used for corresponding light-repeating ship.
Fig. 3 has demonstrated the influence of chromatic dispersion to optical signal pulse shape.Shown in Fig. 3 a, it is very wide to go into fine preceding light pulse power flat region, and rising edge and trailing edge proportion are less, and the light pulse peak power is lower.And the later light pulse (seeing Fig. 3 b) of process 50kmG655 optical fiber is owing to be subjected to the influence of chromatic dispersion, the pulse power flat region narrows down, peak power increases, and the shared time of rising edge and trailing edge is bigger, and the slope of rising edge and trailing edge does not reduce than having with no chromatic dispersion effect pulsion phase.Thereby the SPM effect can be strengthened through the influence of certain chromatic dispersion accumulation back paired pulses in pulse.
Be how example explanation chromatic dispersion influences the SPM effect with no initial chirp light pulse below.Light pulse is transmitted in G652 or G655 optical fiber after the segment distance, and the high fdrequency component transmission is fast under dispersion interaction, the low frequency component transmission is slow, causes video stretching, and rising edge and trailing edge time are elongated, and the pulse flat accounts for whole burst length ratio and diminishes.After amplifying through optical relay, pulse peak power uprises, and the slope of rising edge and trailing edge does not descend, as the pulse shape after the process 50kmG655 Optical Fiber Transmission among Fig. 3 b.The SPM effect is more a lot of by force than the pulse of no chromatic dispersion accumulation when entering next section Optical Fiber Transmission like this.If when optical relay amplifies, carry out dispersion compensation simultaneously, the pulse shape compensation to going into fine prepulse shape as Fig. 3 a, then can be suppressed the SPM effect well.
Fig. 4 is the typical system configuration figure after original system is improved.Multiple signals synthesize one the tunnel through wave multiplexer, are input to erbium-doped fiber amplifier through attenuator and amplify, and are input in the long-distance optical fiber then and transmit.Long-distance optical fiber divides multistage, connects the one-level light-repeating ship between the optical fiber of adjacent two segment lengths way.
Light-repeating ship comprises erbium-doped fiber amplifier (EDFA), attenuator and a dispersion compensation module (DCM).Described dispersion compensation module is to select according to the various parameters of CHROMATIC DISPERSION IN FIBER OPTICS, transmission range and optical signal pulses on the transmission link.Each light-repeating ship shown in Figure 4 comprises two erbium-doped fiber amplifiers (EDFA), two attenuators and a dispersion compensation module (DCM), attenuator of first erbium-doped fiber amplifier input termination, another attenuator and dispersion compensation module are connected between the first erbium-doped fiber amplifier output and the second erbium-doped fiber amplifier input.
Usually, optical fiber bigger apart from difference between the adjacent light relay station in real system adopt similar centralized compensation mode shown in Figure 1 mostly in order to save cost, but this mode limited single ripple launched power of each signal wavelength.The present invention adopts different dispersion compensation modules in growing apart from the cascade transmission course, disperse to carry out dispersion compensation.Adopt the mode of all carrying out dispersion compensation at each grade light-repeating ship as Fig. 4, and before being input to each section optical fiber, signal all pulse is adjusted to the approximate fine prepulse shape of going into shown in Figure 3 according to the situation of warbling of 10G light source, suppressed the influence of SPM effect so greatly, reduced the restriction of going into fine single wave power, for dwdm system, then reduced requirement the power equalization ability to every section optical fiber.Other also is subjected to the influence of optical pulse shape as nonlinear effects such as XPM effects, by taking all factors into consideration multiple nonlinear effect, adjust the shape of every section optical fiber input pulse of concatenation system, can the good restraining effect be arranged nonlinear effects such as SPM effect, XPM effects.
Fig. 5 and Fig. 6 are respectively the dispersion profile figure that Fig. 1 and Fig. 4 transmission system are simplified when not considering that light pulse such as warbles at factor, just can obtain the difference of centralized compensation and dispersion compensation by comparison diagram 5 and Fig. 6.As shown in Figure 5, because per 4 optical relays carry out dispersion compensation one time in Fig. 1 system, dispersion values is constantly accumulated before carrying out dispersion compensation, and signal had all accumulated certain dispersion values when every section optical fiber was gone into fibre except that first, five section optical fiber, and this moment, the SPM effect was comparatively serious.And from dispersion profile figure shown in Figure 6 as can be seen, the chromatic dispersion cumulant was almost nil when every section optical fiber was gone into fibre, this moment the SPM effect a little less than.If consider factors such as pulse chirp, chromatic dispersion accumulated value when then every section optical fiber is gone into fibre no longer is the smaller the better, but need to keep a suitable value, just there is the problem of scientific management dispersion profile in this, just by adjusting dispersion compensation, make flashlight when each section of input optical fiber the pulse Adjusting Shape to the fine preceding state of going into shown in similar Fig. 3 a.
Carry out dispersion compensation at each light-repeating ship, dispersion values minimum when making light pulse enter long-distance optical fiber to transmit, reduce SPM effect intensity like this, reduce the accumulation of SPM effect paired pulses distortion effect, thereby suppressed optical signal spectrum broadening and system performance degradation.This example is to be example with no initial chirp pulse, for the initial chirp pulse is arranged, still adopt and disperse dispersion compensation schemes, but chromatic dispersion compensation quantity need be adjusted according to the initial chirp situation.
Claims (5)
1, is used for the method for the inhibition of long haul transmission system from phase modulated SPM, based on the system that contains wave multiplexer, fiber amplifier, the long-distance optical fiber of multistage and be connected the light-repeating ship between the optical fiber of adjacent two segment lengths way, it is characterized in that comprising the steps: in growing apart from the cascade transmission course, adopt different dispersion compensation modules, disperse to carry out dispersion compensation.
2, according to the method for the described inhibition of claim 1, it is characterized in that: in growing, in each grade light-repeating ship, carry out dispersion compensation and optical relay and amplify, adjust optical pulse shape, to suppress self phase modulation apart from the cascade transmission course from phase modulated SPM.
3, according to the method for the described inhibition of claim 1 from phase modulated SPM, it is characterized in that: described dispersion compensation module is to select according to the various parameters of CHROMATIC DISPERSION IN FIBER OPTICS, transmission range and optical signal pulses on the transmission link.
4, a kind of system that is used for long Distance Transmission, comprise long-distance optical fiber and be connected the adjacent two segment lengths light-repeating ship between the optical fiber on the way, light-repeating ship comprises the fiber amplifier and the attenuator of polyphone, it is characterized in that: every grade of light-repeating ship also comprises different dispersion compensation modules, disperses to carry out dispersion compensation.
5, according to the described system that is used for long Distance Transmission of claim 4, it is characterized in that:
Described dispersion compensation module and an attenuator are connected between the first fiber amplifier output and the second fiber amplifier input.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021205574A CN1231009C (en) | 2002-05-30 | 2002-05-30 | Method for restraining self phase modulation (SPM) |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021205574A CN1231009C (en) | 2002-05-30 | 2002-05-30 | Method for restraining self phase modulation (SPM) |
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| Publication Number | Publication Date |
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| CN1463090A CN1463090A (en) | 2003-12-24 |
| CN1231009C true CN1231009C (en) | 2005-12-07 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB021205574A Expired - Lifetime CN1231009C (en) | 2002-05-30 | 2002-05-30 | Method for restraining self phase modulation (SPM) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1925378B (en) * | 2005-08-30 | 2011-02-23 | 中兴通讯股份有限公司 | Color dispersion compensating method for hybrid transmission line crowded wavelength-division multiplex system |
| CN102386968B (en) * | 2010-08-31 | 2015-07-15 | 富士通株式会社 | Self-phase modulation noise calculating device, removing device and optical coherent receiver |
| CN116886195B (en) * | 2023-09-07 | 2023-11-10 | 中国人民解放军国防科技大学 | High-precision long-distance multi-station optical fiber time transmission method based on code division multiple access |
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