CN1456932A - Dynamic feedback regulating and controlling method for power and gain chart of optical fibre Raman amplifier - Google Patents

Abstract

The method obtains a correlation linear matrix which is convenient for experimental measurement by utilizing perturbation theory and approximate method to establish simple matrix algorithm in depending upon relation of FRA gain spectrum variation amount and multiwavelength pumping light power regulation amount based on FRA actual operation state in engineering system of wavelength division multiplexing. To calculate out the corresponding regulation value of pumping light power according to the differential value of gain spectrum at monitored apparent gain spectrum off-flag, the on-line dynamic feedback regulation and control can be achieved for FRA power and gain spectrum in large scale of dynamic scope.

Description

The dynamic feedback regulate and control method of fiber Raman amplifier power and gain spectral

Technical field

The dynamic feedback regulate and control method of fiber Raman amplifier (FRA) power and gain spectral belongs to high-speed wideband optical fiber communication and optical amplifier technology field, particularly the dynamic equalization of channel gain spectrum and power spectrum in wavelength-division multiplex (WDM) Networks of Fiber Communications of use FRA.

Background technology

Along with the rapid growth of multiple communication services such as data, voice, image, multimedia in recent years, the wdm optical communication system transmission capacity is constantly upgraded.As the Optical Amplification Technology of a new generation, FRA demonstrates tempting application prospect in high speed, high capacity, long distance D WDM Networks of Fiber Communications with its unique low noise, broadband, excellent specific property that service band is adjustable.In recent years, the technological breakthrough of high power pumping lasing light emitter has effectively promoted the research and development progress of FRA, and its engineering practicalization more and more receives publicity, and has become in recent years research and development " focus " both at home and abroad.

The principle of work of FRA is different fully with EDFA, and it is nonlinear optical effect-stimulated Raman scattering (SRS) of utilizing high power laser light pump transmission optical fiber self-light signal is directly amplified.Such as, with 14 * * pump light of nm wave band injects conventional quartz transport optical fiber, can be 15 * * the nm wave band obtains the gain of light.

Fig. 1 provides the distributed FRA light channel structure of a backward pumping.Adopt wavelength to be respectively 1425,1433,1463 and 4 laser diodes (LD) of 1493nm make pumping source, synthetic a branch of by multi-wavelength wave multiplexer (MWB), straight-through through the 111-114 of light splitting coupler (1:99DC11) end, be injected into 100km Transmission Fibers (SMF) through the coupling of the 121-123 of wave division multiplex coupler (WDM) end again, SRS in the excitation fiber, 15 * * flashlight of nm wave band is from the F1 end input of Transmission Fibers, and the acquisition distributed Raman is amplified in propagating the way, amplifying signal light is straight-through from the output of F2 end through the 123-122 of WDM12 end, is composed by spectrometer (OSA12) monitor signal optical output power.Draw 1% pump light from 113 ends of 1:99DC11, by spectrometer (OSA11) monitoring pump light output power spectrum.

Compare with EDFA, FRA has following important feature:

1, the service band of FRA is decided by pumping wavelength, can realize the broadband light amplification with the pump light of suitable wavelength in the whole transmission bandwidth scope (1292-1660nm) of optical fiber, is easy to expand new communication band.

2, FRA has the gain spectral of broad, and the about 20nm of the smooth scope of intrinsic raman gain spectrum of single wavelength pumping adopts a plurality of wavelength pumpings of suitable power ratio can be with the further broadening of gain spectral.

3, FRA is that a kind of pump light of following produces the distributed amplifier of gain along optical fiber, has good noisiness, helps the capacity upgrade that increases intersegmental distance, prolongs transmission link and be convenient to old system.

The typical transmission bandwidth of wdm optical communication system now is 32nm (C-band) or 80nm (C+L wave band).For the FRA that uses in the system, it is as far as possible little not only to require its gain spectral to rise and fall in whole transmission bandwidth scope, also requires to have the function of gain spectral being carried out online adjustment, particularly dynamic regulation.For example: in the wdm optical communication network project is implemented, need to adjust image intensifer and depart from because of the gain spectral that the difference of design parameter and practical application condition causes; In the network operation, enter the node amplifier the number of channel may with on the channel/down or the reconstruct of network increase and decrease, channel power also may all will cause the dynamical distortion of node optical amplifier gain spectrum or output power spectrum because of the difference fluctuation of routed path; In addition, when system upgrade or transmission line were safeguarded, the variation of channel number and power also can cause the change of gain spectral.Therefore, online adjustment, the particularly dynamic regulation of light amplifier gain spectrum or output power spectrum are the key technical problems that WDM optical transport network practicability must solve.

At present, multi wavelength pumping FRA power and gain spectral adjustment technology have two classes:

1, system channel power spectrum lump equilibrium: in transmission system, suitably assign the adjustable broad band optical filters of loss spectra shape (to be called DGE (DGE), as the cascaded optical fiber acousto-optic filter, cascade liquid crystal F-P wave filter etc.), multi-stage cascade is amplified the channel power spectrum of back distortion and carry out shaping, each channel power is kept in balance.At present, DGE is commonly used in experimental system.Yet, DGE can introduce big insertion loss (～10dB), not only influence the noisiness of transmission system, and cost an arm and a leg, also must dispose image intensifer to compensate its added losses.Therefore, DGE generally is used for long haul transmission system or loop transmission experiment, and a plurality of optical nodes are regulated and control simultaneously, and inconvenience is with FRA module installation one by one.

2, FRA channel gain spectrum automatic equalization: the power of certain several channel of monitoring or spontaneous Raman scattering (ASRS) output spectrum of amplification in FRA, with the channel light power that monitors or ASRS spectrum variable quantity FEEDBACK CONTROL pumping light power, the gain spectral shape of multi wavelength pumping is adjusted.Yet because of monitoring variable is determined jointly by a plurality of pumping light powers, the convergence of feedback method is difficult to determine; In addition, regulating the speed by the gain spectral of FEEDBACK CONTROL is restricted, and is difficult to use in the system of regulation and control at a high speed that requires.Therefore, though this technology is widely-used in Erbium-Doped Fiber Amplifier (EDFA) (EDFA) product, uses among the FRA of a plurality of wavelength pumpings and run into very big difficulty.

The physical substance that light amplifier gain is composed online adjustment is to make the constant target gain spectral level of setting of its apparent gain spectrum in dynamic operation by adjusting pumping light power.This is relatively easy for conventional EDFA, because the gain spectral of EDFA is determined by the population inversion degree of Er-doped fiber fully, as long as determine the population inversion degree of target gain spectral correspondence, pumping light power is suitably adjusted in variation according to the apparent gain spectrum, and control population inversion degree is constant can to keep the constant of gain spectral.Yet the shaping mechanism of FRA gain spectral and EDFA fundamental difference: the first, there is not " population inversion degree " such physics reference in FRA; The second, the gain spectral of multi wavelength pumping FRA is formed by stacking by the gain spectral of each pumping wavelength, and the SRS effect that in the pumping amplification process, also exists between the different wave length pump light and add between the flashlight, make each wavelength pump light independent mutually to the contribution of gain spectral.Therefore, attempt to realize that by the luminous power of adjusting a plurality of pumping wavelengths the online adjustment of FRA gain spectral is very difficult that key is to locate a kind of simple algorithm to FRA change in gain amount and multi wavelength pumping optical power adjustment amount.

Summary of the invention

The object of the present invention is to provide and a kind ofly realize the fiber Raman amplifier power of FRA power and the online adjustment of gain spectral and the dynamic feedback regulate and control method of gain spectral by the luminous power of adjusting a plurality of pumping wavelengths.

The objective of the invention is to weak point, propose a kind of simple matrix algorithm, in order to realize the new technology of the online dynamic regulation of a kind of FRA gain spectral the FRA dynamic parameter at prior art.Its basic ideas are: the actual working state of FRA from the WDM engineering system, utilize the perturbation theory approximation method to set up the simple matrix algorithm of multi wavelength pumping optical power adjustment amount and FRA gain spectral variable quantity dependence relation, obtain a dependent linearity matrix of being convenient to experiment measuring; Apparent gain according to monitoring is composed the difference that departs from the target gain spectral, goes out the corresponding adjustment amount of pumping light power by this matrix computations, thereby realizes the online dynamic regulation of FRA gain spectral in big dynamic range.

For illustrating the principle of work of the present invention about the online regulate and control method of FRA gain spectral, brief description utilizes the perturbation theory method to set up the simple matrix algorithm of pumping light power adjustment amount and gain spectral variable quantity dependence relation.

In actual applications, FRA is usually operated at small-signal or nearly small-signal state, and pumping light power depends primarily on interaction between pump light along the distribution of optical fiber.For a FRA that N pumping wavelength arranged, pump light can be write as following matrix form along the transmission rule of optical fiber: $\frac{{\mathrm{dP}}_p\left(z\right)}{\mathrm{dz}}=-{\mathrm{\α}}_p{P}_p\left(z\right)-[R_p\·P_p\left(z\right)]P_p\left(z\right)......\left(1\right)$ P wherein _p(z) be N * 1 vector of representing pumping light power, α _pBe N * 1 vector of representing the pump light loss, R _pIt is a N * N matrix of representing Raman gain coefficienct between each pump light wavelength.In addition, N * 1 vector of pump light along optical fiber integration (abbreviation pumping integration) represented in one of definition: $I={\∫}_0^L{P}_p\left(z\right)\mathrm{dz},$ Be used for calculating the gain of FRA in the analysis below.If input pumping light power changes a Δ P in a small amount _{P, in}, P then _p(z) and I will become P respectively _p(z)+Δ P _p(z) and I+ Δ I.With P _p(z)+Δ P _p(z) substitution (1) formula is ignored Δ P _p(z) second order term can obtain one about Δ P _p(z) linear homogeneous differential equation group: $\frac{{\mathrm{d\ΔP}}_p\left(z\right)}{\mathrm{dz}}=-{\mathrm{\α}}_p{\mathrm{\ΔP}}_p\left(z\right)-[R_p\·P_p\left(z\right)]{\mathrm{\ΔP}}_p\left(z\right)-\left[R_p{\·\mathrm{\ΔP}}_p\left(z\right)\right]P_p\left(z\right)=A\left(z\right){\mathrm{\ΔP}}_p\left(z\right).....\left(2\right)$ Wherein A (z) is a N * N matrix, represents under optic fibre characteristic and the apparent gain pumping light power along the influence of fiber distribution.

Δ P _p(z) can be by (2) formula forward Euler method numerical solution, getting Δ z is step-length, then has

ΔP _p(0)＝ΔP _p，in

ΔP _p(Δz)＝ΔP _p(0)+A(0)ΔP _p(0)Δz＝[1+A(0)Δz]ΔP _p，in

ΔP _p(2Δz)＝ΔP _p(Δz)+A(Δz)ΔP _p(Δz)Δz＝[1+A(0)Δz]ΔP _p，in

...

ΔP _p[(k+1)Δz]＝ΔP _p(kΔz)+A(kΔz)ΔP _p(kΔz)Δz＝[1+A(kΔz)Δz][1+A(0)Δz]ΔP _p，in

So ..., Δ I can be calculated by following formula $\mathrm{\ΔI}=\underset{k}{\mathrm{\Σ}}{\mathrm{\ΔP}}_p\left(\mathrm{k\Δz}\right)\mathrm{\Δz}$ $=\{1+[1+A\left(0\right)\mathrm{\Δz}]+[1+A\left(\mathrm{\Δz}\right)\mathrm{\Δz}\left]\right[1+A\left(0\right)\mathrm{\Δz}]+\mathrm{LL}\}{\mathrm{\Δz}\·\mathrm{\ΔP}}_{p,\mathrm{in}}$ $={H\·\mathrm{\ΔP}}_{p,\mathrm{in}}........\left(3\right)$ Wherein H is a N * N matrix, represents the linear relationship between pumping light power variation and the variation of pumping integration.

The gain spectral of FRA is by pumping integration I decision, and for M input channel, gain spectral can be expressed as

G _Net=-α _sL+T _SRS+ 4.343R _P-sI (4) is G wherein _NetBe M * 1 vector of representing each channel net gain, α _sBe the loss of each channel, R _P-sBe the M * N matrix of Raman gain coefficienct between a representation signal optical wavelength and pump light wavelength, T _SRSBe one and represent M * 1 vector that the channel power spectrum tilts due to the interchannel SRS effect.In great majority were used, FRA output signal luminous power was much smaller than input signal light power, thereby T _SRSMainly, irrelevant with the gain of FRA by the input signal light power decision.If the pumping integration changes Δ I, then obtain corresponding gain spectral variable quantity and be by (4) formula

Δ G _Net=4.343R _P-sΔ I (5) in the adjustment of gain spectral, Δ G _NetRefer to the poor of online FRA apparent gain spectrum and target gain spectral.Corresponding to Δ G _NetOptimum Δ I can obtain by (5) formula with the linear least square method $\mathrm{\ΔI}={(4.343\·R_{p-s}^T{\·\mathrm{\ΔR}}_{p-s})}^{-1}\·R_{p-s}^T{\·\mathrm{\ΔG}}_{\mathrm{net}}\≡R{\·\mathrm{\ΔG}}_{\mathrm{net}}....\left(6\right)$ Here, Zui You implication is meant the optimum under the least square meaning.R is a N * Metzler matrix, represents apparent gain spectrum and the difference of target gain spectral and the linear relationship between optimum pumping integration adjustment amount, and it is determined by the Raman gain coefficienct of Transmission Fibers fully.In conjunction with (3), (6) two formulas, for given target gain spectral, optimum pumping light power adjustment amount can be calculated by following formula:

ΔP _p，in＝Π·ΔG _net (7a)

Π=H ^-1R (7b) wherein Π is a N * Metzler matrix, form by R and H, wherein R is a normal matrix that is determined by optic fibre characteristic fully, H then has relation with optic fibre characteristic and pumping light power along the distribution of optical fiber, can utilize (3) formula to calculate.

(7) formula shows, when online FRA apparent gain spectrum departs from target gain spectral Δ G _NetThe time, for reaching the optimum pumping light power adjustment amount Δ P of target gain spectral _{P, in}With Δ G _NetMaintenance is with the linear relationship of Π matrix correlation, thereby provides a simple and complete matrix algorithms for the regulation and control of FRA gain spectral.

Under actual conditions, inject each wavelength pumping optical power change Δ P of Transmission Fibers _{P, in}Inconvenience is directly measured, and the variation that can only measure the automatically controlled parameter of pumping light power indirectly.At the linear work district of pumping source, Output optical power P _pWith corresponding automatically controlled parameter C _p(curtage) is linear, then (7a) formula can be rewritten into:

Δ C _p=Π _dΔ G _NetOr ${\mathrm{\Π}}_d^{-1}{\·\mathrm{\ΔC}}_p={\mathrm{\ΔG}}_{\mathrm{net}}......\left(8a\right)$

Π _dΠ in=K Π (8b) formula _dBe the correlation matrix that experiment records, K is the normal matrix of the linear relationship of each wavelength pumping light power of description and automatically controlled parameter.

The method of the invention is characterised in that: the actual working state of its FRA from wavelength-division multiplex (WDM) engineering system, utilize perturbation theory and approximation method to set up the simple matrix algorithm of multi wavelength pumping optical power adjustment amount and FRA gain spectral variable quantity dependence relation, obtain a dependent linearity matrix of being convenient to actual measurement; Depart from the difference of target gain spectral again according to monitoring apparent gain spectrum, go out the corresponding adjusted value of pumping light power, thereby in big dynamic range, realize the online dynamic feedback regulation and control of FRA power and gain spectral by this matrix computations; It contains following steps successively.

(1) with the difference G of determination of experimental method apparent gain spectrum with the target gain spectral _NetWith the automatically controlled parameter adjustment amount of pumping C _pLinear dependence matrix Π _d:

(1.1) power configuration of adjustment each pumping wavelength of FRA to be measured makes its gain spectral reach the target requirement;

(1.2) regulate a certain pump wavelength _{P, 1}Automatically controlled parameter C _{P, 1}Changing its luminous power, but keep the luminous power of other wavelength constant simultaneously, obtain C _pThe plain C of an only non-zero optical in the column matrix _{P, 1}

(1.3) measure the variation delta G of optional feature channel apparent gain _{Net, 1}

(1.4) calculate Π with following formula _d ^-1The respective column of matrix; ${\mathrm{\Π}}_d^{-1}{\·\mathrm{\ΔC}}_p={\mathrm{\ΔG}}_{\mathrm{net}}$

(1.5) the rest may be inferred, adjusts each pump wavelength one by one _{P, N}Automatically controlled parameter C _{P, N}To change its luminous power respectively, make by row and record complete Π _d ^-1Matrix;

(1.6) to Π _d ^-1Get the contrary Π that obtains _d

(2) online feedback regulation and control FRA gain spectral

(2.1) yield value of input target gain spectral optional feature channel; The above-mentioned Π that records _dMatrix;

The apparent gain value of feature channel and be input to the control circuit system of FRA when (2.2) moving with light monitoring modular (OPM) monitoring system;

(2.3) calculate gain bias Δ G automatically _Net

Judge Δ G _Net=0?

If Δ G _Net≠ 0, then by the Π in the Control Software _dMatrix computations goes out the adjustment amount Δ C of corresponding automatically controlled parameter _pTo regulate the pumping light power of each wavelength, repeated execution of steps (2.2), (2.3) are judged Δ G once more again _NetWhether be zero;

If: Δ G _Net=0, then apparent gain is composed just constant level in the target gain spectral, and program stops.

The physical basis of described method concerns based on the linear dependence between gain spectral variable quantity and the pumping light power variable quantity, realize adjustment by adjusting pumping light power, for the online dynamic regulation of FRA gain spectral provides a kind of simple and effective automatically controlled accent pumping method to multi wavelength pumping FRA gain spectral.This method both had been applicable to distributed FRA, also was applicable to discrete FRA.

Described method is based on the difference Δ G of the spectrum of apparent gain shown in (7a) formula with the target gain spectral _NetWith optimum pumping light power adjustment amount Δ P _{P, in}The retention wire sexual intercourse, its linear dependence matrix Π can be calculated by (7b) formula according to R matrix and H matrix, wherein R be one fully by the normal matrix of optic fibre characteristic decision, H then has relation with optic fibre characteristic and pumping light power along the distribution of optical fiber, can be calculated by (3) formula.

Described Δ G _NetWith Δ P _{P, in}Π matrix linear dependence can measure Δ G by experiment _NetWith the automatically controlled parameter adjustment amount of pumping Δ C _pΠ _dThe matrix linear dependence is come equivalence.Described automatically controlled parameter C _pLook automatically controlled the mechanism of different pumping source Output optical power and different: for semiconductor laser diode (LD) pumping source, the automatically controlled parameter C of described each wavelength pumping light power _pIt is the drive current (or voltage) of each LD; For the fiber Raman laser pump source, the automatically controlled parameter C of described each wavelength pumping light power _pBe the control voltage of relevant wavelength fiber laser cavity output coupling ratio.

Described Π _dThe mensuration of matrix does not require the variation of the whole channel gain spectrum of monitoring, can select the foundation of the change in gain amount of certain characteristics channel as the pumping light power adjustment, to reduce Π _dThe dimension of matrix.Adjust the power configuration of each pumping wavelength of FRA to be measured earlier, make its gain spectral reach the target requirement; The automatically controlled parameter of regulating a certain pumping wavelength again makes Δ C _pHave only a nonzero element in the column matrix, measure the variation delta G of feature channel apparent gain _Net, calculate Π by (8a) formula _d ^-1The respective column of matrix; Adjust the automatically controlled parameter of each pumping wavelength one by one and change its luminous power respectively, then can record complete Π by row _d ^-1Thereby, obtain Π _dMatrix.With the Π that records _dMatrix writes in the Control Software of FRA.

Evidence: it is strong that this method has adaptability, and the adjustment time is short, and equipment is simple, the advantage that cost is low.

Description of drawings

Fig. 1 is the light channel structure synoptic diagram of the distributed FRA of embodiment of the invention backward pumping.

Fig. 2 is embodiment of the invention Π _dChange the gain spectral of each wavelength pumping light power in the matrix measuring process one by one.

Fig. 3 is the Π of the embodiment of the invention by actual measurement _dEach corresponding wavelength pumping light power of the different target gains of matrix computations.

Fig. 4 is the gain spectral that the embodiment of the invention is adjusted with each wavelength pumping light power one average light gain relationship of Fig. 3 gained.

Fig. 5 is embodiment of the invention Π _dThe actual measurement gain spectral of matrix secondary feedback adjusting.

Fig. 6 utilizes Π matrix algorithms of the present invention that FRA is carried out the result of calculation of gain spectral and power spectrum dynamic regulation,

(a) dynamic regulation of FRA gain spectral,

(b) dynamic regulation of FRA power spectrum.

Fig. 7 is a hardware principle block diagram of the present invention.

Fig. 8 is the program flow diagram of single-chip microcomputer among the present invention.

Embodiment

Utilize relevant Π matrix algorithms as follows in conjunction with the concrete grammar that Fig. 7, Fig. 8 regulate and control FRA power and gain spectral:

1, the measuring of Π matrix:,, directly measure Δ G by experiment according to (7a) formula from practical application though the Π matrix can obtain according to Fiber-optic parameter and pumping condition Theoretical Calculation _NetWith Δ P _{P, in}Determine that the Π matrix is more easy and effective.Here be noted that:

-at Δ G _NetActual measurement in, and do not require the variation that yet is not easy to monitor whole gain spectral, the foundation that only needs to select the change in gain amount of certain characteristics channel to adjust as pumping light power.Like this, can reduce the dimension M of Π matrix, make and measure and computation amount.For example,, as monitor the change in gain of 4 feature channels, just then Π is reduced to one 4 * 4 matrix for a FRA who adopts 4 wavelength pumpings.

-for Δ P _{P, in}Practical measurement, do not need to be not easy to directly to measure each wavelength pumping optical power change of injecting Transmission Fibers, automatically controlled parameter C yet _pVariation, can obtain correlation matrix Π by (8a) formula _dWith Π _dReplace Π that Output optical power P is depended in the influence of power and gain spectral regulating effect _pWith corresponding automatically controlled parameter C _pBetween linear degree.If this linearity is not high, (8b) scale factor K in the formula is not normal matrix, then uses Π _dCan introduce than mistake.Yet, for the semiconductor laser pumping source, in certain output power range, Output optical power P _pWith corresponding automatically controlled parameter C _pBetween (drive current or voltage) good linear relationship is arranged; For the fiber Raman laser pump source, the reflectivity that utilizes piezoelectric ceramics regulation and control fiber grating is to regulate the laser power of respective wavelength, Output optical power P _pWith corresponding automatically controlled parameter C _pGood linear relationship is also arranged between (Piezoelectric Ceramic voltage) usually.Therefore, with Π _dThe error that replaces Π that power and gain spectral are regulated and control can be given and being ignored.

Π _dThe experiment measuring step of matrix is as follows: at first, adjust the power configuration of each pumping wavelength of FRA to be measured, make its gain spectral reach the target requirement; Then, regulate a certain pump wavelength _{P, 1}Automatically controlled parameter C _{P, 1}And change its luminous power, keep the luminous power of other wavelength constant, then Δ C _pHas only a nonzero element C in the column matrix _{P, 1}, measure the variation delta G of feature channel apparent gain _{Net, 1}, then can calculate Π by (8a) formula _d ^-1The respective column of matrix; And the like, adjust each pump wavelength one by one _{P, N}Automatically controlled parameter C _{P, N}And change its luminous power respectively, then can record complete Π by row _d ^-1Matrix is got thus against obtaining Π _d

2, the online regulation and control of FRA gain spectral:, will set the yield value of target gain spectral feature channel and the Π of above-mentioned actual measurement in FRA module making and debug phase _dMatrix writes the Control Software of FRA in advance; The apparent gain value of feature channel when moving with light monitoring modular (OPM) monitoring system is input to the control circuit system of FRA, calculates gain bias Δ G _NetBy the Π in the Control Software _dMatrix computations goes out the adjustment amount Δ C of corresponding automatically controlled parameter _pAnd regulate the pumping light power of each wavelength, make the constant level of apparent gain spectrum in the target gain spectral.

The FRA experimental system of making pumping source with 4 LD of employing shown in Figure 1 is an example, and Transmission Fibers is 100km general single mode fiber (SMF), intends being used for 160 channel C+L wave band dwdm optical communication systems.Signal optical source is made in wide range ASE source with a C+L wave band (1525-1610nm), the about 4mW of gross output, from F1 end input Transmission Fibers, with the F2 end monitoring output spectrum of spectrometer OSA12 from Transmission Fibers, the difference of output power (dBm) spectrum that pumping laser records when opening and closing is the turn off gain spectrum of FRA.Monitor the Output optical power of each pumping wavelength with spectrometer OSA11 from 113 ends of light splitting coupler 1:99 DC11, monitor the corresponding driving electric current simultaneously.Regulate the power configuration of each pumping wavelength, measure the target gain spectral of average net gain pact-12dB, in Fig. 2, put mark, the about 0.8dB of gain fluctuation amplitude with " ■ "; Regulate the drive current of every LD one by one again and change the luminous power of each pumping wavelength, measure each corresponding gain spectral respectively, shown in other spectrum shapes among the figure.Calculate Π thus _d ^-1Each matrix element of matrix, and then obtain corresponding Π _dMatrix.

Utilize the Π of described mensuration _dMatrix is according to the offset G of FRA apparent gain spectrum under the dynamic operation to the target gain spectral _Net, calculate corresponding Δ P _{P, in}Related electric control parameter adjustment amount Δ C _p, by Control Software the luminous power of each pumping wavelength is adjusted, can be by the online dynamic regulation of automatically controlled accent pump means realization to the FRA gain spectral.

According to the Π that records _dMatrix, the variation range of setting average gain calculates the pumping light power that keeps gain spectrum flattening, as shown in Figure 3 from-17dB to-7dB.As seen from the figure, the net gain G of corresponding each pumping wavelength _NetWith pump power P _{P, in}Keep good linear relationship.Utilize the determined net gain G of Fig. 3 _NetWith pump power P _{P, in}Relation, the drive current of regulating each pumping LD is measured each self-corresponding gain spectral, as shown in Figure 4 to change the luminous power of each pumping wavelength.As can be seen, [G in the dynamic range of 6dB _Net∈ (15dB ,-9dB)], the gain spectral degree is more smooth, and gain fluctuation is less than 1.2dB.See also that from figure excessive gain adjustment will cause the inclination of gain spectral, this is because the result that perturbation approximation brings.

The Π that described method is measured under a certain pumping sequence _dMatrix has suitable universality, promptly utilizes same Π _dMatrix can be adjusted other pumping light power combination by automatically controlled parameter in sizable gain variation range.This characteristic makes Π _dMatrix both can be used for the automatically controlled accent pump of one-time-reach-place, also can be used for the secondary feedback regulation, promptly adjust pumping light power at every turn after, can be once more according to the deviation of adjusted apparent gain spectrum with the target gain spectral, utilize original Π _dThe trimming value of the automatically controlled parameter of matrix computations is carried out the secondary adjustment.This secondary feedback regulation can make online gain spectral adjustment have bigger dynamic range.

On the basis of Fig. 4,, utilize the same Π that records once more according to the side-play amount of initial adjustment apparent gain spectrum to the target gain spectral _dEach wavelength pumping light power of matrix and matrix algorithms correction, Fig. 5 provide the net gain that gain spectral is carried out recording after the secondary feedback adjusting and compose.As can be seen, the secondary feedback regulation increases dynamic range, and gain spectral can both keep smooth in the 10dB scope.

Described method not only can be used for online FRA gain spectral and gets dynamic regulation, also can be used to the dynamic regulation to output power spectrum.

Fig. 6 provides the result of calculation that the Π matrix algorithms is used for power blockage.Adopt the C+L wave band FRA of 5 wavelength pumpings in the calculating, pumping wavelength is respectively 1423nm, 1433nm, 1443nm, 1463nm and 1493nm, and Transmission Fibers is 100 kilometers LEAF optical fiber, imports 160 channels, covers the C+L wave band.(a) and (b) two figure are net gain spectrum and the Output optical power spectrum of corresponding FRA respectively, heavy line is represented the most smooth net gain spectrum and the corresponding output power spectrum under the input of 0dBm/ch signal light power, fine line then is under the input signal light power decline 6dB situation, net gain spectrum before pumping is adjusted and Output optical power spectrum.As can be seen, it is upward to short wavelength side that input signal light power decline causes average gain to increase with gain spectral, and output signal luminous power spectrum the more important thing is that the decline of input signal makes the whole decline of whole power spectrum except the influence that is subjected to the gain spectral variation.Dotted line among the figure is to utilize adjusted net gain spectrum of Π matrix algorithms and Output optical power spectrum, the basic original level of getting back to of adjusting of visible Output optical power spectrum, and corresponding net gain spectrum has increased 6dB.Dot-and-dash line then is to utilize net gain spectrum and the Output optical power spectrum that obtains behind the Π matrix secondary feedback regulation on the basis first the adjustment among the figure, and as can be seen, revised Output optical power spectrum returns to original level fully, and corresponding net gain spectrum is also more smooth.

The outstanding advantage of the inventive method is: the first, gain spectral adjustment mechanism is combined together with the light amplification process, it is minimum that Power penalty is dropped to, and need not to dispose in addition DGE, and structure is greatly simplified, and equipment cost reduces; The second, the key parameter Π in the algorithm _dMatrix can measure by experiment, and the Π that measures under a certain pumping sequence _dMatrix has certain universality, need not to measure respectively at different situations; Three, algorithm is based on simple matrix operation, and simplification leeway is arranged, and the gain spectral adjustment can once be calculated realization, need not feedback, and the adjustment time is short, is applicable to dynamic adjustment; Four, this method also can be used for feedback system, and the dynamic range that this moment, gain spectral was adjusted is big, and convergence is fast.

Claims (3)

1. the dynamic feedback regulate and control method of fiber Raman amplifier power and gain spectral, it is characterized in that: the actual working state of its fiber Raman amplifier from the wavelength-division multiplex engineering system, utilize perturbation theory and approximation method to set up the simple matrix algorithm of multi wavelength pumping optical power adjustment amount and fiber Raman amplifier gain spectral variable quantity dependence relation, obtain a dependent linearity matrix of being convenient to actual measurement; Depart from the difference of target gain spectral again according to monitoring apparent gain spectrum, go out the corresponding adjusted value of pumping light power, thereby in big dynamic range, realize the online dynamic feedback regulation and control of fiber Raman amplifier power and gain spectral by this matrix computations; It contains following steps successively.

(1) with the difference G of determination of experimental method apparent gain spectrum with the target gain spectral _NetWith the automatically controlled parameter adjustment amount of pumping C _pLinear dependence matrix Π _d:

(1.1) power configuration of each pumping wavelength of adjustment testing fiber raman amplifier makes its gain spectral reach the target requirement;

(1.2) regulate a certain pump wavelength _{P, 1}Automatically controlled parameter C _{P, 1}Changing its luminous power, but keep the luminous power of other wavelength constant simultaneously, obtain C _pThe plain C of an only non-zero optical in the column matrix _{P, 1}

(1.3) measure the variation delta G of optional feature channel apparent gain _{Net, 1}

(1.4) calculate Π with following formula _d ^-1The respective column of matrix; ${\mathrm{\Π}}_d^{-1}\·\mathrm{\Δ}{C}_p=\mathrm{\Δ}{G}_{\mathrm{net}}$

(1.5) the rest may be inferred, adjusts each pump wavelength one by one _{P, N}Automatically controlled parameter C _{P, N}To change its luminous power respectively, make by row and record complete Π _d ^-1Matrix;

(1.6) to Π _d ^-1Get the contrary Π that obtains _d

(2) online feedback regulation and control fiber Raman amplifier gain spectral

(2.1) yield value of input target gain spectral optional feature channel; The above-mentioned Π that records _dMatrix;

The apparent gain value of feature channel and be input to the control circuit system of fiber Raman amplifier when (2.2) moving with light monitoring modular (OPM) monitoring system;

(2.3) calculate gain bias Δ G automatically _Net

Judge Δ G _Net=0?

If Δ G _Net≠ 0, then by the Π in the Control Software _dMatrix computations goes out the adjustment amount Δ C of corresponding automatically controlled parameter _pTo regulate the pumping light power of each wavelength, repeated execution of steps (2.2), (2.3) are judged Δ G once more again _NetWhether be zero;

If: Δ G _Net=0, then apparent gain is composed just constant level in the target gain spectral, and program stops.

2. according to claim 1, the dynamic feedback regulate and control method of described fiber Raman amplifier power and gain spectral is characterized in that: for semiconductor laser diode (LD) pumping source, and the automatically controlled parameter C of described each wavelength pumping light power _pBe drive current or the voltage of each LD.

3. according to claim 1, the dynamic feedback of described fiber Raman amplifier power and gain spectral is raised control method, it is characterized in that: for the fiber Raman laser pump source, and the automatically controlled parameter C of described each wavelength pumping light power _pBe the control voltage of relevant wavelength fiber laser cavity output coupling ratio.

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