CN1710840A - Channel power equalizer based on non-balanced loss optical fiber non-linear environment - Google Patents
Channel power equalizer based on non-balanced loss optical fiber non-linear environment Download PDFInfo
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Abstract
Belonging to technical area of optical fiber communication, the invention includes a non-linear optical fiber loop mirror composed of an annular set, 1:1 fiber coupler and a segment of transmission fiber connected to each other. One end of the annular set is connected to an input end of the 1:1 fiber coupler. An optical attenuator is inserted at unsymmetrical position inside the non-linear optical fiber loop mirror. One piece of polarisation controller is setup at two port of 1:1 fiber coupler respectively. Further, device in use for introducing non-reciprocal phase bias is setup inside the non-linear optical fiber loop mirror. Through few parameters designed, the invention implements self-adaptive quick and effective balancing control without multiplexing, demultiplexing channel; meanwhile, gets rid of restriction of bi-directional EDFA in NALM scheme furthest so as to lower complexity of system and operational difficulty.
Description
Technical field
The invention belongs to technical field of optical fiber communication, particularly the channel power equalization methods of wavelength-division multiplex system.
Background technology
As everyone knows, wavelength-division multiplex technique is the mainstream technology of long-distance optical fiber transmission main line still not, and with the combination of optical-fiber network technology, become the developing direction of optical-fiber network of future generation.Wavelength-division multiplex technique is exactly a plurality of wavelength optical signals to be grouped together transmit in an optical fiber, and the transmission capacity of simple optical fiber is improved greatly.Present technical merit can have been accomplished the signal of 80,160 of simple optical fiber transmission even more a plurality of wavelength.Like this, the signal to noise ratio severe exacerbation that how to keep the signal to noise ratio of each wavelength signals identical in transmission course, avoids competition or other reason owing to interchannel to cause some channel just becomes an important technological problems of wavelength-division multiplex system.
The equalization request of wavelength-division multiplex system can be divided into three levels: (1) at first requires used image intensifer identical to the gain of each channel, i.e. gain spectrum flattening.Simultaneously, when reasons such as traffic carrying capacity variation make number of channel generation increase and decrease, during such as the upper and lower speech channel of generation, require amplifier to keep constant to the gain of residue channel, avoid the interference of upper and lower speech channel to normal transmission channel, be gain spectral locking, this is the basic demand of wavelength-division multiplex system equilibrium.(2) total power signal rises and falls when the number of channel is constant, cause the improper increase of loss such as a certain section Transmission Fibers owing to fault, the gross power that enters image intensifer so will reduce, thereby at this moment should change Amplifier Gain keeps each channel still to maintain on original level from the power of amplifier output, could get up Fault Isolation, in order to avoid whole system is impacted.If link load changes and the number of channel changes generation simultaneously, when the change gain keeps power output constant, also to keep each channel gain identical so.Promptly no matter input signal power is owing to any reason changes, and it is stable that the power output of each channel all should keep.Power output strangulation that Here it is is the requirement of wavelength-division multiplex system equilibrium at second level of image intensifer proposition.The requirement of (3) the 3rd levels is called channel power equilibrium (Channel by channel equalization), this is at various dynamic changes in the wavelength division multiplexed optical network, can cause the power difference of channel and interchannel such as Add/drop Voice Channel or wavelength conversion etc., requirement has a kind of mechanism can compensate those to have experienced many losses and the lower channel of power ratio, simultaneously the higher channel of those power ratios is given suitable inhibition, finally make the power of each channel equate heavily again, just require to adjust one by one by channel, this is system dynamics equilibrium truly.
At the requirement of first level, the general at present gain flattening filter that adopts.With erbium-doped fiber amplifier (EDFA) is example, adopts gain flattening filter to equate in the gain that a certain initial conditions is issued to each channel, promptly reaches gain spectrum flattening.When initial conditions changes, when input optical power being changed,, just can keep original population inversion level as long as adjust the power of pump light or change the power that injects auxiliary signal light such as number of channel increase and decrease, reach the purpose of locking flat gain spectrum.Requirement at second level, usually Amplifier Gain all leaves certain surplus when systems organization, in transmission link, insert simultaneously certain decay, when counter the changing of link load, adjust the attenuation of inserting, cooperate gain spectrum flattening to lock simultaneously and just can meet the demands.
Gain flattening filter has a variety of, such as long period fiber grating, Bragg grating, Mach-Chen De (Mach-Zehnder) interference filter etc.If equalization filter is a dynamic adjustable, just can the simultaneous adaptation number of channel change or the equalization request of link load when changing, mobility is more intense.By thermal effect an arm of Mach-Zehnder interferometer is carried out phase adjusted, adopt liquid crystal technology or multiple channel acousto luminous effect etc. can realize the equalization filter of dynamic adjustable.What be worth emphasizing is that although this class device can dynamically change the filtering spectrum shape, spectral resolution is high not enough, can't accomplish separately each channel to be regulated, and therefore can not satisfy the equalization request of the 3rd level.
The basic skills of the tri-layer channel power equilibrium of generally adopting in the utility system is earlier channel separation (demultiplexing) at present, respectively the power of each channel is regulated by one group of power adjustments unit (such as attenuator array) then, and then all channels are reconfigured (multiplexing) get up to continue transmission.The scheme of this wavelength regulation one by one can adopt discrete component to realize, the report that adopts integrated technology to realize is also arranged, such as silicon waveguide Mach-Zehnder interferometer array and micro mechanical system etc.The subject matter of this scheme at first is that the insertion loss is big, because the process of demultiplexing and multiplexing and power adjustments all can be introduced bigger loss; Adopt integrated technologies such as silicon waveguide, though compact conformation, volume are less, polarization correlated also bigger.The more important thing is, although various technical scheme realizes the physical mechanism difference of adjusting, all need to adopt the regulon identical with channel number, under the bigger situation of channel number, need the unit of control a lot, operational ton is very big.And adjustment process needs artificial participation to be or by program control, limited speed is in the speed of microcontroller processing signals, at least in hundred or ten microsecond magnitudes.
In order to overcome these deficiencies, people such as the Ueyn L Block of Stanford Univ USA have proposed to utilize non-linear amplification ring mirror (NALM) to realize the idea of channel power equilibrium at multi-wavelength phase shift keying (PSK) or frequency shift keying (FSK) system.In fact the light channel structure of NALM is exactly a Sagnac ring of having placed fiber bidirectional erbium-doped fiber amplifier (EDFA) 14 in asymmetric position as shown in Figure 1.Wherein, the 11st, circulator, the 111st, input port, the 112nd, output port.Input light is by circulator 11, be divided into two bundles through 1: 1 behind the optical coupler 12 again, respectively along clockwise direction and counterclockwise, and internal dispersion compensated fiber 13 (DCF) amplify again and pass through ring internal dispersion compensated fiber again through amplifying earlier by encircling earlier respectively, just interfere when two-beam is got back to 1: 1 optical coupler, the result of interference determines light to be reflected back or exported by the another port transmission by 1: 1 original input port of coupler.Because Ke Er (Kerr) effect exists a nonlinear phase relevant with luminous power poor between the two-beam, under suitable input power range, the higher channel of power will experience bigger interference loss and realize the multichannel power equalization.People such as Ueyn L Block point out in article, at multi-wavelength phase shift keying (PSK) or frequency shift keying (FSK) system, adopt cascade NALM to substitute the cascade EDFA of common long Distance Transmission relay point, can realize adaptive power equalization.Their simulation result shows, after the transmission through 16 grades of NALM, the 15dB of channel power difference during by input is decreased to 4dB, has along with transmission range and cascade progression increase and the characteristics of convergence, also not have relevant experiment report unfortunately so far.
The NALM scheme that the present application people proposes people such as Ueyn L Block adopts am signals to carry out experimental study.Discover, essentially among the NALM will introduce a two-way EDFA, and this EDFA can bring some problems inevitably.At first, two-way EDFA can not resemble the method that adopts the interpolation isolator the common amplifier and suppress the amplified spont-aneous emission noise, so noise can be bigger.Secondly, use at multi-wavelength, need in two-way EDFA, add gain flattening filter and come flat gain spectrum, but, common gain flattening filter all is a reflection-type, and under the situation that can not adopt isolator, the Rayleigh scattering of the reflection of flat filter and DCF optical fiber etc. are echoed mutually, be easy to form self-excited vibration, NALM encircles basic cisco unity malfunction when serious.
Summary of the invention
The present invention is in order to overcome the weak point of prior art, propose a kind of channel power equalizer, not only can just can carry out adaptive, balanced control fast and effectively by the design of a few parameter to each channel based on non-balanced loss optical fiber non-linear environment mirror (L-NOLM); Farthest break away from simultaneously the restriction of two-way EDFA in the NALM scheme again, reduced the complexity and the operation easier of system.
The channel power equalizer that the present invention proposes based on non-balanced loss optical fiber non-linear environment mirror (L-NOLM), comprise a circulator, and by 1: 1 fiber coupler and one section nonlinear fiber loop mirror that Transmission Fibers connects and composes, an output of this circulator links to each other with an input of 1: 1 fiber coupler; It is characterized in that asymmetric position inserts an optical attenuator in this nonlinear fiber loop mirror, two ports of 1: 1 coupler are placed a Polarization Controller respectively in the ring mirror.
The input power level that the present invention requires when reducing balanced operation reduces the negative effect that nonlinear effect is brought system, and a device that is used to introduce the non-reciprocal phase biasing can also be set in the nonlinear fiber loop mirror ring.
The described device that is used to introduce the non-reciprocal phase biasing can adopt optical frequency shifter to realize that described optical frequency shifter may be selected to ripe commercial product.
Described 1: 1 fiber coupler is ripe commercial product.
Described optical attenuator can be commercial adjustable optical attenuator, also can be the attenuator of fixing, even can be or part is the insertion loss of components and parts itself.
Described Polarization Controller is ripe element, and product is arranged.
Operation principle of the present invention:
The present invention propose in order to realizing the balanced loss nonlinear fiber loop mirror (L-NOLM) of wavelength-division multiplex system channel power equilibrium, with the basic difference of existing NALM be that bidirectional optical amplifier has been changed into attenuator, increased by two Polarization Controllers simultaneously.When adopting this structure of the present invention, light is earlier through being attenuated the device decay again after the Transmission Fibers clockwise, and counterclockwise light earlier through overdamping, with smaller power through Transmission Fibers.Because optics Ke Er (Kerr) effect, the phase change difference that two-beam accumulates when getting back to two ports of 1: 1 coupler by Transmission Fibers exists a nonlinear phase relevant with luminous power poor, and this phase difference will directly influence the result of interference.Under suitable input power range, the higher channel of power will experience bigger interference loss and realize the channel power equilibrium.Two Polarization Controllers in the ring are used for adjusting that the polarization direction is parallel to each other when making suitable, counterclockwise light get back to two ports of 1: 1 coupler, guaranteeing to have smooth background transmission spectrum, each wavelength signals by nonlinear fiber loop mirror, to have an input polarization of identical power transfer characteristic curve and power transfer characteristic curve and signal irrelevant, is fit to the requirement that multi-wavelength is used.
Technical characterstic of the present invention and effect
The present invention adopts the nonlinear fiber loop mirror (L-NOLM) of balanced loss to realize multi channel power equalization, inherited the advantage of NALM, can channel be distinguished according to channel power, and have a non-linear loss characteristic relevant with signal power, under needn't be, only need design by a few parameter just can carry out adaptive, equilibrium fast and effectively and control each channel to channel demultiplexing, multiplexing situation; Farthest break away from simultaneously the restriction of two-way EDFA in the NALM scheme again, reduced the complexity and the operation easier of system.
Description of drawings
Fig. 1 is non-linear amplification ring mirror (NALM) the power equalizer light channel structure that people such as the Ueyn L Block of Stanford Univ USA proposes;
Fig. 2 is balanced loss nonlinear fiber loop mirror (L-NOLM) embodiment 1 light channel structure of the realization multi-wavelength channel power equilibrium of the present invention's proposition;
The power transfer characteristic curve of the L-NOLM power equalizer that the present invention that Fig. 3 obtains for Theoretical Calculation proposes;
Fig. 4 adds embodiment 2 light channel structures of the L-NOLM power equalizer of non-reciprocal phase biasing for the present invention;
Fig. 5 adopts embodiment 3 light channel structures of the L-NOLM power equalizer of non-reciprocal phase biasing for the present invention;
No bias power equalizer shown in Figure 2 carries out background transmission spectrum that the balanced experiment measuring of multi-wavelength channel power obtains and input, output spectrum to Fig. 6 for the present invention adopts;
Fig. 7 is the background transmission spectrum that adopts the power equalizer experiment measuring that is added with the device of non-reciprocal phase biasing shown in Figure 4 and obtain and input, output spectrum.
Embodiment
The employing balanced loss nonlinear fiber loop mirror (L-NOLM) that the present invention proposes is realized the technology of wavelength-division multiplex system channel power equilibrium, reaches accompanying drawing in conjunction with the embodiments and is described in detail as follows:
The present invention propose in order to balanced loss nonlinear fiber loop mirror (L-NOLM) embodiment 1 light channel structure of realizing the equilibrium of wavelength-division multiplex system channel power as shown in Figure 2, comprise a circulator 21, and by 1: 1 fiber coupler 22 and one section nonlinear fiber loop mirror that transmission connects and composes with DCF optical fiber 24, an output 212 of this circulator links to each other with an input 221 of 1: 1 fiber coupler; Asymmetric position inserts an optical attenuator 25 in this nonlinear fiber loop mirror, and a Polarization Controller 23,26 is placed at two ports, 223,224 places of 1: 1 coupler respectively in the ring mirror.
The operation principle of present embodiment is: input light enters from port 211, through arriving the port 221 of 1: 1 optical coupler behind the circulator, through dividing two equal bundles of success rate behind the coupler, transmits in ring along clockwise direction with counterclockwise respectively.Light is got back to port 224 by Polarization Controller 23, DCF optical fiber 24, optical attenuator 25 and another Polarization Controller 26 successively from port 223 beginnings clockwise; Light is then got back to port 223 from port 224 in reverse order counterclockwise.At this moment two-beam interferes at 1: 1 optical coupler place, and the result of interference determines light to reflex to circulator by original input port 221 or exported by another port 222 transmissions.Characteristic decision by fiber coupler itself, from port 221 input couple light to port 224 time can add the phase hit of pi/2, and the light that is coupled to port 223 does not have this additional saltus step, from port 223 and 224 processes to port 221 and port 222 couplings similar phase change is arranged also.Therefore, promptly do not need to consider under the condition of nonlinear effect light and light identical phase accumulation of experience in ring clockwise counterclockwise in common low-power, so, phase difference at port 222 place's two-beams is π, produces complete destructive interference, and produces constructive interference at port 221 places.Simply say to be exactly that light will all reflex to circulator through port 221, export from the port 213 of circulator again.But the present invention has placed an attenuator 25 on the asymmetric position in encircling, and be attenuated the device decay again behind the process DCF of the light elder generation optical fiber clockwise, and counterclockwise light is earlier through overdamping, with smaller power process DCF optical fiber.Because optics Ke Er (Kerr) effect, two-beam exists a nonlinear phase relevant with luminous power poor in the phase change difference of getting back to port 223,224 accumulation by DCF optical fiber, and this phase difference will directly influence the result of interference.Under suitable input power range, the higher channel of power will experience bigger interference loss and realize the multichannel power equalization.
Shown in Figure 3 is the power transfer characteristic curve of the L-NOLM of Theoretical Calculation, can see, power output is a fluctuations along with input power increases, and near maximum, the variation of power output is more smooth.If input optical power the foot, scope in change, then Output optical power can change in the scope of Rout; In other words, if the output-power fluctuation scope Rout of the given permission of the present invention just has the input power dynamic range Rin of a correspondence.Can prove by calculating, be no more than 1dB if require power output to rise and fall, then the excursion of input power can be 4～5dB, if require output to rise and fall less than 2dB, then the variation of input power can be 6～7dB, the power equalization effect of Here it is L-NOLM.
But under the actual conditions, unavoidably there is certain residual birefringence in the Transmission Fibers in the NOLM ring.In the ring residual birefringence can influence light in ring when transmission polarization state evolution process, suitable, counterclockwise light is produced the additional transmission phase difference that has nothing to do with power.Like this, when the signal of a plurality of wavelength of wavelength-division multiplex system was imported simultaneously, not only the background transmission spectrum under low power condition will be uneven, and along with input power increases, the power delivery curve difference of each wavelength, power output also can be relevant with the input polarized state of light simultaneously.These all are the unbalanced factors additional to input signal.Discover and experimental results show that through theory, the residual birefringence of Transmission Fibers can remedy by other birefringence, the concrete operations way is: import a lower powered wide range signal source, suitably adjust the offset controller 23 and 26 in the ring then, the two-beam that makes the interior transmission of process ring get back to coupler port 223 and 224 reverts to and is parallel to each other, and so above-mentioned additional unbalanced factor just can be eliminated substantially.
Further the operation principle of analyzing L-NOLM can be known, counterclockwise light is very low through the laggard power of going into DCF optical fiber of overdamping, basically need not consider its nonlinear phase shift, it is exactly that the nonlinear phase of two-beam is poor that the nonlinear phase that accumulates when light is through DCF optical fiber so clockwise changes.After the length of DCF optical fiber and non linear coefficient decision, the nonlinear phase difference is mainly by the luminous power decision, reaches near the peak value shown in Figure 3 in order to make the nonlinear phase difference, and the input signal power of requirement can not be too low.But too high input power can cause difficulty in actual applications, and the nonlinear phase shift accumulation more or less can produce harmful effect to the continuation transmission of signal.
In order to meet the requirements of phase difference and to avoid the big problem of input power, the present invention further proposes to be provided with one and is used to introduce the device that non-reciprocal phase is setovered in L-NOLM.
The device of this non-reciprocal phase biasing can adopt distinct methods such as birefringence, magneto optical effect and acousto-optic shift frequency to realize.Fig. 4 and shown in Figure 5 be two kinds of L-NOLM light channel structure embodiment that adopt acousto-optic shift frequency methods to realize the non-reciprocal phase biasing, be respectively described below:
The light channel structure of embodiment 2 as shown in Figure 4, be on the basis of embodiment shown in Figure 21, to have increased by two acousto-optic frequency shifters, promptly comprise a circulator 41, and by 1: 1 fiber coupler 42 and one section nonlinear fiber loop mirror that DCF optical fiber 45 connects and composes, an output 412 of this circulator links to each other with an input 421 of 1: 1 fiber coupler; Asymmetric position inserts an optical attenuator 46 in this nonlinear fiber loop mirror, and a Polarization Controller 43,47 is placed at two ports, 423,424 places of 1: 1 coupler in the ring mirror respectively; On this basis, adding an acousto- optic frequency shifters 47 and 44 between optical attenuator 46 and the offset controller 48 and between DCF optical fiber 45 and another offset controller 43 respectively.Two acousto-optic frequency shifters require the shift frequency amount identical, and are all positive shift frequency or are all negative shift frequency.
The operation principle of present embodiment is: signal is since the port 423 of 1: 1 coupler 42, gets back to coupler port 424 by offset controller 43, acousto-optic frequency shifters 44, DCF optical fiber 45, optical attenuator 46, second acousto-optic frequency shifters 47 and second offset controller 48 successively in the direction of the clock; Light is then got back to port 423 from port 424 in reverse order counterclockwise.Suppose that frequency shifter 44 is L1 to the fiber lengths of coupler port 423, frequency shifter 47 is L2 to the fiber lengths of coupler port 424, fiber lengths between two frequency shifters is that L incident light frequency is f, two acousto-optic frequency shifters are positive shift frequency and the shift frequency amount is fa, so, light by L1, passes through L with frequency f+fa with frequency f clockwise, by L2, light then passes through L2, L, L1 with frequency f, f+fa, f+2fa counterclockwise with frequency f+2fa.Like this, the shift frequency amount of acousto-optic frequency shifters and the difference between length L 1 and the L2 non-reciprocal phase that determined the to obtain size of moving.This nonreciprocal phase shift is superimposed upon on the above-mentioned nonlinear phase difference relevant with power, L-NOLM is operated near the peak value of curve shown in Figure 3 and does not need very big input power, realized phase bias.
The light channel structure of embodiment 3 as shown in Figure 5, present embodiment also increases by two acousto-optic frequency shifters on the basis of Fig. 2, promptly comprise a circulator 51, reach the nonlinear fiber loop mirror that is connected and composed by 1: 1 fiber coupler 52 and DCF optical fiber 54, optical attenuator 57 and Polarization Controller 53,58, an output 512 of circulator links to each other with an input 521 of 1: 1 fiber coupler.On this basis, between optical attenuator 57 and DCF optical fiber 54, add two acousto- optic frequency shifters 55 and 56 successively.The shift frequency amount of two acousto-optic frequency shifters is identical, and another is negative shift frequency for positive shift frequency for one of them.
The operation principle of present embodiment is: flashlight successively by offset controller 53, DCF optical fiber 54, acousto-optic frequency shifters 55, acousto-optic frequency shifters 56, optical attenuator 57 and Polarization Controller 58, is got back to coupler port 524 from 523 beginnings of coupler port then clockwise; Light is got back to port 523 from port 524 in reverse order counterclockwise.The shift frequency amount of two acousto-optic frequency shifters is identical but the shift frequency direction is opposite, if the fiber lengths between them is L, it is the size of phase bias amount that shift frequency amount and L decision non-reciprocal phase are moved.Embodiment 2 compares with 3, two acousto-optic frequency shifters and optical attenuator the same side in ring among the embodiment 3, and the insertion loss of acousto-optic frequency shifters constitutes the part of asymmetric loss, and the loss of acousto-optic frequency shifters all is supplementary load loss among the embodiment 2.
Technique effect of the present invention is described as follows by experiment:
Experiment one, the L-NOLM power equalizer structure of employing embodiment 1.In the present embodiment, the length of DCF optical fiber is 10km, and abbe number is-80ps/nm/km the about 7dB of total losses, the about 7dB of optical attenuator attenuation.Adopt three broadband signals that wavelength signals is come the analog wave division multiplexing system of coverage 20.6nm in the experiment, the earlier low rate modulation of the employing Hybrid-modulated Signal of High Speed Modulation is again simulated high speed NRZ (RZ) modulation signal.Three signal wavelengths are respectively 1533.8nm, 1541.2nm and 1554.4nm, and high speed Sine Modulated frequency is 10GHz, and low speed square-wave frequency modulation frequency is 200KHz, duty ratio 1/20.The experiment beginning, at first the low power wide spectrum signal is imported from port 211, the spontaneous emission light of an erbium-doped fiber amplifier output is adopted in this experiment, the gross power of 1525nm～1565nm wavelength band is no more than-5dBm, two Polarization Controllers 23 and 26 in the adjustable ring simultaneously make that the output spectra that measures from port 213 with spectrometer is smooth as far as possible and power is high as far as possible.At this moment the output spectra that obtains is shown in Fig. 6 (a), and unevenness can reach in the 0.3dB in the wave-length coverage of 1525nm～1565nm.Then, two Polarization Controllers are constant in the retaining ring, import above-mentioned Hybrid-modulated Signal, and use the spectrum of spectrometer measurement input and output respectively at input port 211 and output port 213 places.It shown in Fig. 6 (b) input spectrum that measures at input port 211 places, its medium wavelength is that three signals of 1533.8nm, 1541.2nm and 1554.4nm are labeled as channel CH1, CH2 and CH3 respectively, between them power difference be respectively 6.3dB (CH1 and CH2) and 2.7dB (CH1 and CH3).
Increase the signal power of input gradually, but keep the power difference of three interchannels constant, in conjunction with the power transfer characteristic curve of L-NOLM shown in Figure 3 as can be known, along with the increase of input power, the power output of each channel also changes thereupon.Shown in Fig. 6 (c), (d) two output spectrums when reaching equilibrium.The CH1 of input power maximum and the CH2 power output of input power minimum reach equal among Fig. 6 (c), be positioned at the both sides of power transfer characteristic curve summit, and the CH3 of input power between them is positioned near the summit of power transfer characteristic curve, power output is than CH1 and CH2 height, and the difference between them is no more than 1.8dB.Be the situation that CH1 and CH3 power output equate shown in Fig. 6 (d), at this moment, the CH1 of input power maximum has crossed the lowest point that power descends, and restarts to rise, and at this moment the power output difference of three channels is greatly about about 1.0dB.
Experiment two, the power equalizer structure of embodiment 2 shown in Figure 4 is adopted in this experiment.Wherein, used DCF optical fiber is the same, the insertion loss 2.3dB of acousto-optic frequency shifters 44, the insertion loss 3.0dB of acousto-optic frequency shifters 47, two frequency shifters are positive shift frequency, and the shift frequency amount is 27MHz, 0.8 meter of the length difference of L1 and L2, about 75 ° of amount of bias, the about 6.5dB of the attenuation of attenuator 46.Measure and adopt the three-wavelength low speed modulation signal that covers 20.9nm, wavelength is respectively 1533.6nm, and 1541.4nm and 1554.5nm carry out the low speed square-wave frequency modulation by acousto-optic modulator respectively, frequency 200KHz, duty ratio 1/20.Testing procedure and top described similar, (the C-band gross power is regulated two offset controllers 43 and 48 under the input condition approximately-5dBm) in low-power wide range source, make that output spectra is smooth as far as possible and amplitude is maximum, shown in Fig. 7 (a), in the 40nm of 1525nm～1565nm scope, background fluctuations is no more than 0.3dB, because the about 2dB of dynamic loss that phase bias is introduced.
The state of protecting two Polarization Controllers then is constant, imports above-mentioned modulation signal.Record input spectrum shown in Fig. 7 (b) at input port IN place, the power difference of CH1 and CH2 is 1.3dB, and the power difference of CH2 and CH3 is 5.5dB.Progressively increase input signal light power, keep the power difference of two interchannels constant.When input power increases to a certain degree, the CH3 of input power maximum crosses summit and begins to descend, and CH1 and CH2 continue to rise, and power difference narrows down in the 1dB, shown in Fig. 7 (c).Along with the input gross power further increases, output spectrum progressively develops from Fig. 7 (c) and is Fig. 7 (d)～7 (g), though the relative size of three channel power outputs all remains within the 1dB changing., import gross power accordingly and change about 3dB to Fig. 7 (g) from Fig. 7 (c).
Claims (4)
1, a kind of channel power equalizer based on the non-balanced loss optical fiber non-linear environment mirror, comprise a circulator, and by 1: 1 fiber coupler and one section nonlinear fiber loop mirror that Transmission Fibers connects and composes, an output of this circulator links to each other with an input of 1: 1 fiber coupler; It is characterized in that asymmetric position inserts an optical attenuator in this nonlinear fiber loop mirror, two ports of 1: 1 coupler are placed a Polarization Controller respectively in the ring mirror.
2, the channel power equalizer based on the non-balanced loss optical fiber non-linear environment mirror as claimed in claim 1 is characterized in that, also is included in a device that is used to introduce the non-reciprocal phase biasing is set in the described nonlinear fiber loop mirror ring.
3, the channel power equalizer based on the non-balanced loss optical fiber non-linear environment mirror as claimed in claim 2, it is characterized in that, describedly be used to introduce the device of non-reciprocal phase biasing for adopting two acousto-optic frequency shifters that the shift frequency amount is identical, the shift frequency direction is identical, one of them acousto-optic frequency shifters is arranged between described optical attenuator and the offset controller, and another acousto-optic frequency shifters is arranged between described Transmission Fibers and another offset controller.
4, the channel power equalizer based on the non-balanced loss optical fiber non-linear environment mirror as claimed in claim 2, it is characterized in that, the described device that is used to introduce the non-reciprocal phase biasing is for adopting two acousto-optic frequency shifters that the shift frequency amount is identical, the shift frequency direction is opposite, and these two acousto-optic frequency shifters are added between described optical attenuator and the Transmission Fibers successively.
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| CN102158284A (en) * | 2011-03-17 | 2011-08-17 | 电子科技大学 | Light signal polarization direction determination and power equalization system |
| CN102932065A (en) * | 2012-11-12 | 2013-02-13 | 武汉邮电科学研究院 | Multi-subchannel gain flat device and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102158284A (en) * | 2011-03-17 | 2011-08-17 | 电子科技大学 | Light signal polarization direction determination and power equalization system |
| CN102158284B (en) * | 2011-03-17 | 2013-09-25 | 电子科技大学 | Light signal polarization direction determination and power equalization system |
| CN102932065A (en) * | 2012-11-12 | 2013-02-13 | 武汉邮电科学研究院 | Multi-subchannel gain flat device and method |
| CN102932065B (en) * | 2012-11-12 | 2015-03-18 | 武汉邮电科学研究院 | Multi-subchannel gain flat device and method |
| CN103364106A (en) * | 2013-07-16 | 2013-10-23 | 扬州森斯光电科技有限公司 | Brillouin optical time domain analyzing and sensing system based on ultra-long annular laser pumping |
| CN103364106B (en) * | 2013-07-16 | 2015-07-29 | 扬州森斯光电科技有限公司 | A kind of Brillouin optical time domain analysis sensor-based system based on the pumping of overlength loop laser |
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