CN102510307B - Optical fiber disturbance system polarization control method and control system based on annealing algorithm - Google Patents
Optical fiber disturbance system polarization control method and control system based on annealing algorithm Download PDFInfo
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Abstract
The invention discloses an optical fiber disturbance system polarization control method and control system based on an annealing algorithm. In the polarization control, an analogue annealing algorithm is used as a control algorithm, and a polarization controller is used for modulating an interference optical wave polarization state. The relevance between two interference signals received by a detector in a distributed optical fiber disturbance positioning system is used as a feedback signal, and the analogue annealing algorithm is used for searching an extra voltage of a corresponding polarization controller when the difference between signals is the smallest. The polarization control system comprises a continuously distributed optical fiber sensing system based on dual Mach-Zehnder optical fiber interferometer, an extrusion type polarization controller, a LiNbO3 birefraction phase modulator, a singlechip system, a computer and algorithm software. The optical fiber disturbance system polarization control method provided by the invention can effectively improve the anti-polarization induced fading ability of the system by controlling the polarization state of the interference light, and can greatly eliminate the influence of the single-mode optical fiber birefraction to the system positioning precision.
Description
Technical field
The invention belongs to sensing and detection technique field.
Background technology
Along with the enhancing of scientific and technological development and people's security protection consciousness, developing the perimeter security system that a kind of investigative range is large, energy consumption is little, cost is low becomes a necessary and problem in the urgent need to address.Distributed optical fiber vibration sensing system relies on it highly sensitive, anti-electromagnetic interference, without advantages such as power supplies, at safety-security areas such as military defense, financial protection, energy security, community's securities, had application widely, and also will have vast application prospect in future.
One of necessary condition of produce interfering due to light wave is exactly that to participate in the light vector direction of vibration of interference identical, has identical polarization direction component.The optical fiber that actual perturbed system adopts is general single mode fiber, and due to the birefringent characteristic of monomode fiber, light wave enters optical fiber rear polarizer state and can change, and causes the polarization state of line polarisation to be degenerated.At sensory field, this can cause visibility of interference fringes to reduce, and even interference fringe disappears, so system is declined greatly to the positioning precision of disturbance.
Although use polarization maintaining optical fibre can keep polarisation of light state constant, because laying distance, the optical fiber of distributed optical fiber vibration sensing system generally all reaches tens kilometers, and use polarization maintaining optical fibre can make system cost too high.Therefore, in actual applications, we must take in another kind of means countermeasure system polarisation of light to degenerate, and the polarization state of compensating light changes, thereby it is inaccurate to eliminate as much as possible the system location that the birefringent characteristic of monomode fiber causes.
Summary of the invention
The present invention seeks to solve existing method and locate inaccurate problem because of the system that the birefringent characteristic of monomode fiber causes, a kind of optical fiber disturbance system polarization control method and polarization control system based on simulated annealing is provided, by the method, adjust the flashlight polarization state in distributed optical fiber vibration sensing system one arm, flashlight polarization state in the keeping system of can trying one's best two arms is consistent, thereby improves the positioning precision of system.
Concrete technical scheme:
1, the basic principle of distributed optical fiber vibration sensing system
Distributed optical fiber disturbance positioning system as shown in Figure 1, this system, based on two Mach-Zehnder fibre optic interferometer principles, utilizes two measuring fibers of two monomode fibers formation Mach-Zehnder fibre optic interferometers in optical cable to respond to optical cable disturbing signal around.
Two-way sensor fibre is two groups of contrary light waves of the direction of propagation simultaneously, optical cable disturbance around can be modulated the phase of light wave of propagating in optical fiber, thereby interference signal is modulated, phase place interferes in coupler through the two-beam of ovennodulation, and interference light outputs to photodetector through circulator.Because disturbance occurrence positions is different to the distance of distributed sensor two ends photodetector, and the propagation velocity of light wave in optical fiber is certain, therefore the time difference of same event according to two photodetectors, detected, can accurately orient locale.Positioning principle as shown in Figure 2.If two photodetector D1 of distributed optical fiber disturbance positioning system and D2 detect the time of same disturbance event and are respectively t
1and t
2, Δ t=t
1-t
2, the length that L is sensing optic cable, x is the position of disturbance point distance the second coupler 5, its ranging formula is
In formula, v is the propagation velocity of light wave in monomode fiber, the m/s of unit, and v=c/n wherein, c is light speed (3 * 10 in a vacuum
8m/s), n is the refractive index of optical fiber.
2, the optical fiber disturbance system polarization control method based on simulated annealing
The present invention adopts simulated annealing as control algolithm, controlling extruding optical-fiber type Polarization Controller controls light signal polarization state, in Polarization Control, using two detectors receive in distributed optical fiber vibration sensing system two paths of signals as input, utilize hour corresponding Polarization Controller applied voltage value of simulated annealing search two paths of signals difference.This method has proposed a kind of the polarization state of interference light in optical fiber to be carried out to control method, can effectively improve the anti-polarization degeneration ability of system, and eliminate to a great extent the impact of monomode fiber birefringence on the disturbances location precision of system.
The performing step of the method is:
1st, in optical fiber vibration sensing system, by the light signal input polarization controller transmitting in an arm of sensor fibre, Jiang Zhe road enters respectively two photodetectors through interference light and another road interference light of Polarization Control, with data collecting card, gathers two paths of signals and inputs computer;
2nd, computer judges the difference adjustment polarization state of two paths of signals contrast by simulated annealing, change the applied voltage value of extrusion pressing type Polarization Controller, flashlight through Polarization Controller is realized to continuous control, and utilize feedback signal to carry out the search of the overall optimum value of algorithm, until reaching when search stops requiring, the degree of correlation of two paths of signals stops; By the polarization state of interference light in this method adjustment System, can effectively suppress the polarization error of data, thus the positioning precision of raising system to disturbance.
Simulated annealing
The iterative process of simulated annealing is the material Slow cooling process in simulated annealing technique.The cooling procedure of annealing is the process that object internal energy slowly reduces, and from the angle of calorifics, whole interior energy reduction process equivalence can be regarded as to the transition of a series of equilibrium states.Be that object internal energy is slowly reduced to zero from higher state by a series of specific temperature spots, between different temperature spots, be heat exchanging process, and be all quasi-balanced state at each temperature spot.Annealing algorithm is applicable to the searching process in hyperspace, has good global optimum search performance, and also has higher convergence rate.
The FEEDBACK CONTROL of Polarization Control, the fact is, in wave plate phase shift solution space, this target function of light intensity is carried out to optimizing.Based on this, the polarization state that the present invention's conception utilizes simulated annealing to carry out retardation control type Polarization Controller is controlled.In the solution space consisting of a plurality of wave plate retardations, the output polarization state light intensity of a fixed-direction has many saddle points, utilizes simulated annealing global convergence should be able to effectively solve the original false convergence problem based on gradient method.
In Polarization Control, with the difference of the two paths of signals that in distributed optical fiber vibration sensing system, two detectors receive, (two paths of signals difference is less, similitude is better, the degree of correlation is higher) as feedback signal, be the desired value of algorithm, so the optimum solution of target function is the applied voltage value of the hour the most corresponding Polarization Controller of two paths of signals difference.It is minimum that two paths of signals difference is tending towards under the effect of algorithm, stops search, and magnitude of voltage corresponding to optimum solution write to Polarization Controller, thereby complete Polarization Control process when two paths of signals difference meets stopping criterion for iteration.
The flow process of this polarization control method is as follows:
The first, the sine wave of applying certain frequency and amplitude to phase-modulator on sensor-based system one arm, as with reference to signal.
Whether the difference that the second, judges in distributed optical fiber disturbance positioning system the two paths of signals that two detectors receive is greater than the threshold value setting, if difference is greater than threshold value, computer runs programs, utilize simulated annealing to search for the optimum voltage value being applied on Polarization Controller, thereby realize Polarization Control.
Two squeezers of the Polarization Controller using in Polarization Control, this problem can be described in order to minor function:
C＝f(V
1，V
2)
V wherein
i, i=1,2 are respectively the magnitude of voltage applying on two squeezers, and C is the degree of correlation of the two paths of signals that in now corresponding navigation system, two photodetectors receive; V when C reaches maximum
ivalue is for optimum voltage value, and now system is in optimum Working, thereby realized Polarization Control, improved the positioning precision of system;
Search procedure as the simulated annealing of Polarization Control is as follows:
(1) initial temperature T is set
0, final temperature T
e, the setting optimal value C of attenuation coefficient α and the two paths of signals degree of correlation
m, initial temperature T wherein
0, final temperature T
eand arranging of α need to take into account global search performance and computing time, and α need satisfy condition: 0 < α < 1; Vectorial X=(V for the state of Polarization Controller
1, V
2) describe, it represents optimization problem C=f (V
1, V
2) a solution vector, generate at random initial solution vector X
0=(V
10, V
20), and will with initial solution vector X
0the degree of correlation C of corresponding two paths of signals
0be assigned to respectively current optimal solution vector X
bwith current optimum degree of correlation C
b, current annealing temperature T=T is set
0;
(2) judgement C
band C
msize, if C
b≤ C
m, end loop, exports optimal solution vector X
bwith optimum degree of correlation C
b; If C
b> C
m, perform step (3);
(3) interior cycle-index n is set, juxtaposition circulation initial value i is 1; With current optimal solution X
bas the center of circle, according to (V
1k-V
1b)
2+ (V
2k-V
2b)
2≤ R
2determine that Radius is in the ，Yuan territory, round territory of R, to get one to separate arbitrarily X
k, and try to achieve and X
kthe degree of correlation C of corresponding two paths of signals
k;
(4) judgement C
kwith C
bsize, if C
k≤ C
b, upgrade optimal solution vector X
bwith current optimum degree of correlation C
b, make X
b=X
kand C
b=C
k, and jump to step (6); If C
k> C
b, perform step (5);
(5) calculating probability P=exp (Δ C/T), wherein Δ C=C
k-C
b, T is current annealing temperature; The random several a that produce between a 0:1, if P>=a accepts X
kfor new optimal solution X
b, otherwise continue with state X
biteration; Cycle-index i=i+1 in upgrading; If i < is n, get back to step 2; If i>=n, according to temperature renewal function T
k+1=α T
kupgrade Current Temperatures and make T=α T;
(6) judgement Current Temperatures T and final temperature T
erelation, as T>=T
etime, get back to step 2; As T < T
etime, program stops, output optimal solution vector X
bwith optimum degree of correlation C
b.
3, a control system that realizes above-mentioned polarization control method, comprising:
Basic distributed fiberoptic sensor based on two Mach-Zehnder fibre optic interferometers: for generation of interference signal, carry out disturbances location, polarization control system is to add what Polarization Control device was realized on the basis of this transducer;
Extrusion pressing type Polarization Controller: have four direction of extrusion staggered squeezers at 45 °, in control procedure, use the first two optical fiber squeezer wherein, the voltage that two squeezers is applied to various combination can carry out different modulation to the polarization state of input light wave, thus the light wave of output different polarization states; Polarization Controller is added in to a wherein road of above-mentioned basic distributed fiberoptic sensor sensor fibre, by modulating the polarization state of this road light signal, realizes Polarization Control;
LiNbO
3birefringent phase modulator: for generation of reference signal, be added in sensor fibre another road corresponding with Polarization Controller place end of basic distributed fiberoptic sensor, for generation of sinusoidal phase modulation, phase modulated signal is interfered and is produced intensity Sine Modulated through two Mach-Zehnder fibre optic interferometers, by two photodetectors, received respectively, if do not exist polarization to degenerate, the two-way interference signal that in basic distributed fiberoptic sensor, two photodetectors receive has fixed delay and amplitude equates;
Data collecting card: the voltage signal to two photodetectors gathers, and send into computer and process;
Computer: realize the processing of the collection signal that data collecting card is sent into by the software programming in computer, to realize the iterative search of best modulation voltage, and the best modulation voltage searching is fed back to Polarization Controller and phase-modulator by Single Chip Microcomputer (SCM) system;
Single Chip Microcomputer (SCM) system: by communicating with computer, output digit signals is directly controlled Polarization Controller; Sine wave output signal, modulates phase-modulator.
This polarization control system is shown in Fig. 5.
Advantage of the present invention and beneficial effect:
At present, most distributed optical fiber disturbance positioning system, owing to not carrying out Polarization Control, causes positioning precision poor.The present invention proposes a kind of polarization control method for distributed optical fiber disturbance positioning system.Utilize the method can effectively improve the anti-polarization degeneration ability of system, and eliminate to a great extent the impact of monomode fiber birefringence on the disturbances location precision of system.The simulated annealing that this method is used is a kind of method of asking for globally optimal solution in nonlinear programming problem, there is good global optimum search performance, and also there is higher convergence rate, can effectively solve the original false convergence problem based on gradient method.
Accompanying drawing explanation
Fig. 1 is distributed optical fiber disturbance positioning system;
Fig. 2 is positioning principle figure;
Fig. 3 is the two paths of signals that does not carry out Polarization Control of distributed optical fiber disturbance positioning system collection;
Fig. 4 is the Polarization Control two paths of signals of system acquisition afterwards;
Fig. 5 is polarization control system;
Fig. 6 is Polarization Control algorithm search schematic diagram;
In figure, 1 and 9 is lasers, and 2 and 10 is first couplers, 5 and 13 is second couplers, 6 and 14 is the 3rd couplers, and 3 and 11 is first optical circulators, and 4 and 12 is second optical circulators, 7a is sensor fibre F1 in optical cable, 7b is sensor fibre F2 in optical cable, and 8a and 18a are the first photodetector D1, and 8b and 18b are the second photodetector D2, the 15th, Polarization Controller, the 16th, LiNbO
3birefringent phase modulator, the 17th, sensing optic cable, the 19th, Single Chip Microcomputer (SCM) system, the 20th, computer, the 21st, capture card.
Embodiment:
Embodiment 1: for the polarization control system of distributed optical fiber disturbance positioning system
As shown in Figure 5, this system comprises:
Extrusion pressing type Polarization Controller 15: have four direction of extrusion staggered squeezers at 45 °, in control procedure, use the first two optical fiber squeezer wherein, the voltage that two squeezers is applied to various combination can carry out different modulation to the polarization state of input light wave, thus the light wave of output different polarization states.Polarization Controller is added in to a wherein road of basic distributed optical fiber sensing system sensor fibre, by modulating the polarization state of this road light signal, realizes Polarization Control;
LiNbO
3birefringent phase modulator 16: for generation of reference signal, be added in sensor fibre another road corresponding with Polarization Controller place end of basic distributed optical fiber sensing system, for generation of sinusoidal phase modulation, phase modulated signal is interfered and is produced intensity Sine Modulated through two Mach-Zehnder fibre optic interferometers, by two photodetectors, received respectively, if do not exist polarization to degenerate, the two-way interference signal that in basic distributed optical fiber sensing system, two photodetectors receive has fixed delay and amplitude equates;
Data collecting card (DAQ Card) 21: the voltage signal to two photodetector 18a and 18b gathers, and send into computer and process.
Computer (PC) 20: realize the processing of the collection signal that data collecting card is sent into by the software programming in computer, to realize the iterative search of best modulation voltage, and the best modulation voltage searching is fed back to Polarization Controller and phase-modulator by Single Chip Microcomputer (SCM) system.
Single Chip Microcomputer (SCM) system (SCM) 19: by communicating with computer, output digit signals is directly controlled Polarization Controller; Sine wave output signal, modulates phase-modulator.
Embodiment 2: polarization control method
It is that line polarisation and polarization direction are consistent that two-beam produces one of essential condition of interference light that participation is interfered exactly, in the hypothesis of the location algorithm of distributed optical fiber disturbance positioning system based on same polarization direction line polarization interference, launches.
Distributed optical fiber disturbance positioning system is mainly used in perimeter protection, seismic monitoring etc., optical fiber used reaches tens of kilometers kilometers even up to a hundred, if application polarization maintaining optical fibre and corresponding kit thereof will be very expensive, the sensor fibre that this system of the consideration based on cost aspect is used is the monomode fiber generally using.
General single mode fiber is due to enchancement factors such as geometry bending, environment temperature variations, and the impact of other nonrandom errors, capital causes fiber birefringence, thereby while causing line polarisation to transmit in general single mode fiber, polarization state changes, and causes the polarization state of line polarisation to be degenerated.Polarization state is degenerated not only can affect interference quality of output signals, and has a strong impact on the positioning precision of whole system.
Figure 3 shows that the two paths of signals that distributed optical fiber disturbance positioning system gathers while not carrying out Polarization Control, the two paths of signals shown in figure differs greatly, and does not see the contact of two paths of signals completely.Point to 128.6m place, position applies disturbance, and positioning result, from 174.9m to 360m random distribution, reaches 231.4m with the maximum deviation of physical location, and average deviation reaches 175.9m, has departed from physical location completely.
Adjust polarization state two paths of signals state afterwards as shown in Figure 4, now two paths of signals is basically identical.Equally the disturbance at 128.6m place, position is positioned, positioning result by 123.4m to 133.7m, with the maximum deviation of physical location be 5.2m, average deviation is 1.6m, positioning precision significantly rises.
Therefore, in the distributed optical fiber disturbance positioning system of practical application, must take Polarization Control to interference light, the variation of compensating interferometer polarization state, thereby the anti-polarization decay ability of raising whole system, the positioning precision of raising system.
As shown in Figure 5, the light signal of sensor fibre one arm is input in Polarization Controller 15, after Polarization Control, two-way interference signal enters respectively two photodetectors, and data collecting card gathers two paths of signals and signal is sent into computer.
The annealing algorithm of computer-internal software is adjusted the position vector of each particle in Chaos particle swarm optimization algorithm according to the degree of correlation of fed back two-way interference signal, change each position vector corresponding be applied to the magnitude of voltage on Polarization Controller squeezer.The polarization state of Polarization Controller incident light wave is carried out continuous control and utilized feedback signal to carry out optimal value search, until the degree of correlation of two paths of signals corresponding to feedback signal stops while meeting search end condition.
Below according to the system shown in Fig. 5, in conjunction with the search routine shown in Fig. 6, first the computational process of the polarization control method based on annealing algorithm is described, then the impact of this control method on system accuracy be described by experiment, the value rule of annealing algorithm parameters has finally been discussed.
1, in order to explain the computational process of annealing algorithm, with certain Polarization Control example, illustrate:
(1) initialization setting.Initial temperature T
0=1, final temperature T
e=0.05, temperature damping factor alpha=0.5, for the setting optimal value C with the two paths of signals degree of correlation
m=0.01, radius R=100, interior cycle-index n=20.The random vectorial X of an initial solution that generates
0=(1251,2870), and will with initial solution vector X
0the degree of correlation C of corresponding two paths of signals
0=0.0495831 is assigned to respectively current optimal solution vector X
bwith current optimum degree of correlation C
b;
(2) due to C now
b=0.0495831 > C
m=0.01, do not meet end condition, continue execution step (3);
(3) in, circulate after 20 times, X
b=(1390,2560), with it corresponding optimum degree of correlation C
b=0.0339063 is greater than C
m, upgrade Current Temperatures T=0.5;
(4) after renewal temperature, repeat interior circulation, until after circulating in 5 times, X
b=(1282,1963), with it corresponding optimum degree of correlation C
b=0.021536 is still greater than C
m, but temperature T=0.03125 < T now
e=0.05, meet end condition, program stops, and now exports optimal solution vector X
b=(1282,1963) and optimum degree of correlation C
b=0.021536;
2, the impact of this control method on system accuracy:
Several parameters in annealing algorithm are set as respectively: initial temperature T
0=1, final temperature T
e=0.05, temperature damping factor alpha=0.5, for the setting optimal value C with the two paths of signals degree of correlation
m=0.01, radius R=100, interior cycle-index n=20.Adjust thus polarization state.
The Polarization Control of table one based on annealing algorithm affects experimental data (unit: m) to system accuracy
The position of the disturbance applying in known experiment is 128.6m, and from experimental result, when not adjusting polarization state, the mean value of location is 304.5m, and known positioning precision while not adjusting polarization state is more than 176m; After adjusting polarization state, the mean value of positioning result is 137.8m, and positioning precision is now in 10m.Can find the positioning precision nearly 130m that risen.As can be seen here, add Polarization Control and can make system more accurate to the location of disturbance, thereby system has been played to the effect of optimizing.
3, the value rule of annealing algorithm parameters:
Below by several groups of description of tests in simulated annealing, initial temperature T
0, temperature damping's constant alpha, radius R and the isoparametric value rule of interior cycle-index n.
(1) initial temperature T
0
Initial temperature T
0, final temperature T
ebe mutually to restrict with temperature damping's constant alpha, therefore should consider.This experiment changes T
0, the selection of other several parameters is respectively: T
e=0.01, α=0.5, C
m=0.02, R=100, n=30.Last convergence effect (optimum degree of correlation C in experiment
b) with convergence time as shown in following table two.
Table two changes initial temperature T
0time restrain effect and convergence time experimental data
| |
1 | 2 | 3 | 4 | 5 | On average | t |
| T 0＝0.2 | 0.0455441 | 0.0309543 | 0.0386342 | 0.0495051 | 0.0340284 | 0.03973322 | 20s |
| T 0＝0.5 | 0.0565112 | 0.0664027 | 0.0312667 | 0.0667577 | 0.024546 | 0.04909686 | 24.8s |
| T 0＝1 | 0.024829 | 0.045174 | 0.0351302 | 0.0296336 | 0.0231083 | 0.03157502 | 27s |
By experimental data, can be found out initial temperature T
0larger, convergence effect is better, but convergence time rising, even program cannot be moved afterwards.The above experimental result of Comprehensive Correlation, considers convergence effect and time used, gets initial temperature T
0within=1 o'clock, experiment effect is best.
(2) temperature damping's constant alpha
Temperature damping's constant alpha has reflected the rate of decay of temperature.This experiment changes α, and the selection of other several parameters is respectively: T
0=1, T
e=0.01, C
m=0.02, R=100, n=30.The convergence effect that experiment obtains and convergence time are as shown in following table three.
When changing temperature damping's constant alpha, table three restrains effect and convergence time experimental data
| |
1 | 2 | 3 | 4 | 5 | On average | t |
| α＝0.2 | 0.0283965 | 0.0501971 | 0.0452508 | 0.0449461 | 0.0327374 | 0.04030558 | 12.5s |
| α＝0.5 | 0.024829 | 0.045174 | 0.0351302 | 0.0296336 | 0.0231083 | 0.03157502 | 27s |
| α＝1 | 0.0324687 | 0.0420882 | 0.0257653 | 0.0302355 | 0.0285679 | 0.03182512 | 1min20s |
By experimental data, can be found out, within the specific limits, temperature damping's constant alpha is larger, and cooling rate is slower, but corresponding quality of separating is higher.The above experimental result of Comprehensive Correlation, the quality of separating when α increases does not significantly improve, but the time had remarkable rising, therefore in experiment, get α=0.5 proper.
(3) peek radius R
Peek radius R in state renewal function has determined the hunting zone of state X.Therefore, when R too hour, program can not search whole solution space, can cause returning be local optimum value rather than overall optimum value; And when R is too large, can cause program to move.This experiment changes R, and the selection of other several parameters is respectively: T
0=1, T
e=0.01, C
m=0.02, α=0.5, n=30.The convergence effect that experiment obtains and convergence time are as shown in following table four.
When changing peek radius R, table four restrains effect and convergence time experimental data
| |
1 | 2 | 3 | 4 | 5 | On average | t |
| R＝10 | 0.117228 | 0.0844735 | 0.117081 | 0.054626 | 0.0660967 | 0.08790104 | 28.4s |
| R＝50 | 0.0873674 | 0.0358196 | 0.11275 | 0.0420517 | 0.0436244 | 0.06432262 | 27.8s |
| R＝100 | 0.024829 | 0.045174 | 0.0351302 | 0.0296336 | 0.0231083 | 0.03157502 | 27s |
By experimental data, can be found out, the R effect of more having a bowel movement is better, and the spent time is fewer, causes sometimes program to be difficult to operation at 100 o'clock, so in this experiment, get R=100 but R is greater than.
(4) interior cycle-index n
The n inside looping is more, and the solution space that program is searched for is larger, and the time consuming longer simultaneously.This experiment changes n, and the selection of other several parameters is respectively: T
0=1, T
e=0.01, C
m=0.02, α=0.5, R=100.The convergence effect that experiment obtains and convergence time are as shown in following table five.
When changing interior cycle-index n, table five restrains effect and convergence time experimental data
| |
1 | 2 | 3 | 4 | 5 | On average | t |
| n＝20 | 0.0699163 | 0.0518094 | 0.0398634 | 0.0287355 | 0.0440567 | 0.04687626 | 19.8s |
| n＝30 | 0.024829 | 0.045174 | 0.0351302 | 0.0296336 | 0.0231083 | 0.03157502 | 27s |
| n＝40 | 0.0302194 | 0.0308112 | 0.0382326 | 0.0327123 | 0.0274071 | 0.03187652 | 36.5s |
By experimental result, can be found out, as n, too hour experiment effect is bad, and when n is too large, program cannot be moved.Consider the factors such as convergence effect, time and program quality, desirable n=30.
Therefore show that by experiment the optimum value of these parameters is respectively: T
0=1, T
e=0.01, C
m=0.02, α=0.5, R=100, n=30.
Claims (3)
1. be applied to a polarization control method for distributed optical fiber disturbance positioning system, it is characterized in that the implementation of the method is:
In distributed optical fiber disturbance positioning system, the light signal of sensor fibre one arm is input in extrusion pressing type Polarization Controller, after Polarization Control, two-way interference signal enters respectively two photodetectors, and data collecting card gathers two paths of signals and signal is sent into computer;
Computer is adjusted the position vector of each particle in simulated annealing according to the degree of correlation of fed back two-way interference signal, change each position vector corresponding be applied to the magnitude of voltage on the first two optical fiber squeezer on extrusion pressing type Polarization Controller, the polarization state of extrusion pressing type Polarization Controller incident light wave is carried out continuous control and utilized feedback signal to carry out optimal value search, until the degree of correlation of two paths of signals corresponding to feedback signal stops while meeting search end condition.
2. method according to claim 1, is characterized in that the detailed process of described simulated annealing is: two squeezers of the extrusion pressing type Polarization Controller using in Polarization Control, this problem can be described in order to minor function:
C=f(V
1,V
2)
V wherein
i, i=1,2 are respectively the magnitude of voltage applying on two squeezers, and C is the degree of correlation of the two paths of signals that in now corresponding navigation system, two photodetectors receive; V when C reaches maximum
ivalue is for optimum voltage value, and now system is in optimum Working, thereby realized Polarization Control, improved the positioning precision of system;
Search procedure as the simulated annealing of Polarization Control is as follows:
(1) initial temperature T is set
0, final temperature T
e, the setting optimal value C of attenuation coefficient α and the two paths of signals degree of correlation
m, initial temperature T wherein
0, final temperature T
eand arranging of α need to take into account global search performance and computing time, and α need satisfy condition: 0< α <1; Vectorial X=(V for the state of extrusion pressing type Polarization Controller
1, V
2) describe, it represents optimization problem C=f (V
1, V
2) a solution vector, generate at random initial solution vector X
0=(V
10, V
20), and will with initial solution vector X
0the degree of correlation C of corresponding two paths of signals
0be assigned to respectively current optimal solution vector X
bwith current optimum degree of correlation C
b, current annealing temperature T=T is set
0;
(2) judgement C
band C
msize, if C
b≤ C
m, end loop, exports optimal solution vector X
bwith optimum degree of correlation C
b; If C
b>C
m, perform step (3);
(3) interior cycle-index n is set, juxtaposition circulation initial value i is 1; With current optimal solution X
bas the center of circle, according to (V
1k-V
1b)
2+ (V
2k-V
2b)
2≤ R
2determine that Radius is in the ，Yuan territory, round territory of R, to get one to separate arbitrarily X
k, and try to achieve and X
kthe degree of correlation C of corresponding two paths of signals
k;
(4) judgement C
kwith C
bsize, if C
k≤ C
b, upgrade optimal solution vector X
bwith current optimum degree of correlation C
b, make X
b=X
kand C
b=C
k, and jump to step (6); If C
k>C
b, perform step (5);
(5) calculating probability P=exp (△ C/T), wherein △ C=C
k-C
b, T is current annealing temperature; The random several a that produce 0～1, if P>=a accepts X
kfor new optimal solution X
b, otherwise continue with state X
biteration; Cycle-index i=i+1 in upgrading; If i < is n, get back to step (2); If i>=n, according to temperature renewal function T
k+1=α T
kupgrade Current Temperatures and make T=α T;
(6) judgement Current Temperatures T and final temperature T
erelation, as T>=T
etime, get back to step (2); Work as T<T
etime, program stops, output optimal solution vector X
bwith optimum degree of correlation C
b.
3. realize a polarization control system for method claimed in claim 1, it is characterized in that this polarization control system comprises:
Basic distributed fiberoptic sensor based on two Mach-Zehnder fibre optic interferometers: for generation of interference signal, carry out disturbances location, polarization control system is to add what extrusion pressing type Polarization Control device was realized on the basis of this transducer;
Extrusion pressing type Polarization Controller: have four direction of extrusion staggered squeezers at 45 °, in control procedure, use the first two optical fiber squeezer wherein, the voltage that two squeezers is applied to various combination can carry out different modulation to the polarization state of input light wave, thus the light wave of output different polarization states; Extrusion pressing type Polarization Controller is added in to a wherein road of above-mentioned basic distributed fiberoptic sensor sensor fibre, by modulating the polarization state of this road light signal, realizes Polarization Control;
LiNbO
3birefringent phase modulator: for generation of reference signal, be added in another road of the sensor fibre corresponding with extrusion pressing type Polarization Controller place end of basic distributed fiberoptic sensor, for generation of sinusoidal phase modulation, phase modulated signal is interfered and is produced intensity Sine Modulated through two Mach-Zehnder fibre optic interferometers, by two photodetectors, received respectively, if do not exist polarization to degenerate, the two-way interference signal that in basic distributed fiberoptic sensor, two photodetectors receive has fixed delay and amplitude equates;
Data collecting card: the voltage signal to two photodetectors gathers, and send into computer and process;
Computer: realize the processing of the collection signal that data collecting card is sent into by the software programming in computer, to realize the iterative search of best modulation voltage, and the best modulation voltage searching is fed back to extrusion pressing type Polarization Controller and phase-modulator by Single Chip Microcomputer (SCM) system;
Single Chip Microcomputer (SCM) system: by communicating with computer, output digit signals is directly controlled extrusion pressing type Polarization Controller; Sine wave output signal, modulates phase-modulator.
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| CN103759806A (en) * | 2014-02-19 | 2014-04-30 | 南京昕天卫光电科技有限公司 | Polarization control device of optical fiber disturbance system |
| CN103926806B (en) * | 2014-05-05 | 2016-03-30 | 北京理工大学 | A kind of lithography illuminating system method for designing realizing pupil polarization state Arbitrary distribution |
| CN103995468B (en) * | 2014-05-26 | 2017-01-11 | 天津大学 | Polarization control method, based on genetic algorithm, of optical fiber disturbance system and device thereof |
| CN103994784A (en) * | 2014-05-26 | 2014-08-20 | 天津大学 | Distributed optical fiber sensing positioning method based on zero crossing point analysis |
| CN103986522B (en) * | 2014-05-29 | 2016-07-06 | 中国科学技术大学 | A kind of polarization recovery methods |
| CN103997386B (en) * | 2014-06-03 | 2017-02-15 | 北京邮电大学 | Method for accurately converting arbitrary modes based on simulated annealing algorithm |
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| CN109361515B (en) * | 2018-11-23 | 2022-05-27 | 山西大学 | Pulsed light high-speed polarization locking method for continuous variable quantum key distribution system |
| CN110455453B (en) * | 2019-09-24 | 2024-09-24 | 广西大学 | Mobile vibration testing device and cable force testing method |
| CN117030000B (en) * | 2023-10-10 | 2024-01-12 | 之江实验室 | Distributed acoustic wave sensing polarization control system and polarization fading inhibition method |
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