CN104406682B - A kind of pair of interference signal correlation adjusting method of Mach Zehnder fiber optic interferometric systems - Google Patents
A kind of pair of interference signal correlation adjusting method of Mach Zehnder fiber optic interferometric systems Download PDFInfo
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- CN104406682B CN104406682B CN201410531551.0A CN201410531551A CN104406682B CN 104406682 B CN104406682 B CN 104406682B CN 201410531551 A CN201410531551 A CN 201410531551A CN 104406682 B CN104406682 B CN 104406682B
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Abstract
The present invention provides a kind of pair of interference signal correlation adjusting method of Mach Zehnder fiber optic interferometric systems, the extrusion stress produced using piezoelectric ceramics produces photoelastic effect, by the use of two-way interference light signal as feedback, the polarization state of two-way interference signal is adjusted to consistent.Using such scheme, polarization state feedback control is carried out by the light to reference arm, the inconsistent inducement signal relative coefficient of polarization characteristic is low in solving the problems, such as double Mach Zehnder fiber optic interferometric systems over long distances, allow the two ways of optical signals for detecting can to keep the good correlation, the time delay of two-way detectable signal can correctly to reflect the positional information in oscillation point.
Description
Technical field
The invention belongs to interference signal correlation regulation technology field, more particularly to a kind of pair of Mach-Zehnder light
The interference signal correlation adjusting method of fine interference system.
Background technology
Two-way Mach-Zehnder fiber interference principles are as shown in figure 1, system is by distributed feedback semiconductor laser (DFB-
LD) 10, optoisolator 11, fiber coupler and photodetector 12 and photodetector 13 are constituted, wherein three fiber arm bags
Including pickup arm 14, reference arm 15, the length of time delay arm 16 can reach 50km, and remaining fiber lengths is very short (1m or so), fixed
Position can be ignored when calculating.
The fiber-optic vibration test system course of work is：The narrow-linewidth laser that Distributed Feedback Laser 10 sends enters three-dB coupler
C1.Two-way light is separated by coupler C1, wherein entering the M-Z being made up of coupler C2 and coupler C3 after isolator 11 all the way
Interference system is transmitted along clockwise direction, is detected to detector PD213 by coupler C4 outputs, the wherein effect of isolator 11
It is to interfere to prevent the two-way light of clockwise, counterclockwise transmission from forming Sagnac；Other light all the way is through coupler C4 along the inverse time
Pin direction is transferred into the M-Z interference systems 17 being made up of coupler C3 and coupler C2, and by coupler C2 outputs to detection
Device PD112 is detected.When being acted on without external disturbance, the output of two detectors only has DC component；When extraneous to sensor fibre applying
During disturbance, two detectors may detect the light-intensity variation as caused by phase place change, so as to realize being able to detect that vibration letter
Number waveform.
When being disturbed at the R in sensor fibre, we set vibration signal and are transferred to PD1 along (CCW directions) counterclockwise
Time used is t1；If the time that vibration signal is transferred to used by PD2 along (CW directions) clockwise is t2.The then biography in CCW directions
Defeated optical path distance is that X is (because sensor fibre length is far longer than coupler C2 to the distance of detector PD1 therefore negligible defeated
Go out to hold distance)；And the transmission optical path distance in CW directions is L1+L2-X；Can then obtain：
Wherein n is optical fibre refractivity, and c is light speed in a vacuum, during the two ways of optical signals that Δ t is detected for detector
Prolong.For the place for having set up optical cable, L1、L2Fixed, as long as therefore can measure between two-way vibration signal when
Prolong Δ t, so that it may orient the position in oscillation point.
This requires the time delay Δ t between two-way vibration signal, is not influenceed by phase place change, and two-way interference signal keeps
Good correlation.
In double Mach-Zehnder fiber optic interferometric systems over long distances, the intensity (light intensity) of two-way interference signal is with oscillation intensity
Phase to two paths of signals is related.Influence of the phase to oscillation intensity (vibration phase A, is shaken as shown in Fig. 2 two-way linearly polarized light
Dynamic phase B) its phase difference 180 degree, when interfering, the light intensity that its interference is obtained is different, the crest of vibrational waveform A
The trough of correspondence vibrational waveform B.During positioning is realized, the optical signal polarization state of two-way interfere arm is change at random,
Cause the light correlation of two-way interference signal low.
Therefore, the prior art is defective, it is necessary to improve.
The content of the invention
The technical problems to be solved by the invention are directed to the deficiencies in the prior art, there is provided a kind of pair of Mach-Zehnder light
The interference signal correlation adjusting method of fine interference system.
Technical scheme is as follows：
A kind of pair of interference signal correlation adjusting method of Mach-Zehnder fiber optic interferometric systems, wherein, including:
Four piezoelectricity squeezers being made up of piezoelectric ceramics, into 45 degree of angle extruding optical fiber on each action direction, form inclined
Shake controller, and the Polarization Controller is added on the time delay arm of light path and is proximate to one end of laser；
By feedback, allow counterclockwise enter interference region polarization state, with clockwise enter interference region polarization state protect
Hold consistent.
Described interference signal correlation adjusting method, wherein, the Polarization Controller is by four direction piezoelectric ceramics structure
Into, by control the voltage at each Polarization Controller the two poles of the earth with realize counterclockwise into interference region light polarization state omnirange without dead
Angle changes.
Described interference signal correlation adjusting method, wherein, the deformation quantity of the piezoelectric ceramics and it is supplied to piezoelectricity to make pottery
The voltage at porcelain the two poles of the earth is related, the deformation quantity of all directions is changed by changing control voltage, and then change piezoelectric ceramics extruding
The deformation quantity of optical fiber.
Described interference signal correlation adjusting method, wherein, by counterclockwise enter interference region polarization state regulation with
The polarization state regulation for entering interference region clockwise is consistent, for allowing the interference signal of generation counterclockwise and clockwise to keep good
Correlation.
Described interference signal correlation adjusting method, wherein, the interference signal for producing counterclockwise and clockwise is deposited
In a carrier wave for low frequency, when the polarization state of two-way interference light is inconsistent, the voltage difference that two detectors are detected is used as feedback
Signal, with full search algorithm, by controlling Polarization Controller input voltage, realizes entering interference region light counterclockwise and clockwise
Polarization state be consistent.
There is advantages below using such scheme：
1st, signal coherency present in double Mach-Zehnder fiber optic interferometric systems over long distances is solved poor, it is impossible to be used for
The problem of vibration signal positioning.
2nd, by the polarization state of time delay arm in automatically controlled piezoelectric ceramics real-time control optical interference circuit, detected with two detectors
Voltage difference realizes the regulation of polarization state as feedback signal --- implementation method is simple, and control circuit, software algorithm are simply easy
OK, and easily realize automatically adjusting in real time.
3rd, realize positioning using general single mode fiber, solve the problems, such as using polarization maintaining optical fibre high cost.
Brief description of the drawings
Fig. 1 is two-way M-Z principle of interferences figure in the prior art.
Fig. 2 is the vibration signal interference effect figure of out of phase in the prior art.
Fig. 3 is automatically controlled Polarization Controller structural representation in the embodiment of the present invention.
Fig. 4 is the round complex plane design sketch of Polarization Controller control polarization state in the embodiment of the present invention.
Fig. 5 is the light path schematic diagram of addition Polarization Controller in the embodiment of the present invention.
Specific embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.
Embodiment 1
Present invention regulation polarization state uses automatically controlled piezoelectric type Polarization Controller, and it is the piezoelectricity being made up of piezoelectric ceramics
Squeezer, the deformation quantity of piezoelectric ceramics is related to the voltage at piezoelectric ceramics the two poles of the earth is supplied to, it is possible to by changing control electricity
Press to change the deformation quantity of all directions, and then change the deformation quantity that piezoelectric ceramics extrudes optical fiber.
Automatically controlled piezoelectric type Polarization Controller is：The photoelastic effect that produces produces phase when extruding optical fiber using piezoelectric ceramics
Position postpones.The fibre core of preferable single-mode fiber is the circle of rule, and the electric field intensity of light propagation rate in all directions is equal, when
When applying a pressure to optical fiber, its fibre core is just similar to an ellipse, and what is produced when piezoelectric ceramics is in extruding optical fiber is double
Refraction, phase difference meets：
Wherein f is the power that optical fiber is subject in unit length, and d is the diameter of light, constant k=9.5 × 10-5Rad/m, δ are
The phase difference of generation.Thus can be by changing plus the pole tension of piezoelectric ceramics two in all directions changes respective direction
Polarization state.
Automatically controlled piezoelectric type Polarization Controller concrete structure the piezoelectricity squeezer of four direction as shown in figure 3, be made up of, its is each
Into 45 degree of angles, 4 squeezers extrude optical fiber to individual action direction from four direction when upper electric：Such as piezoelectricity squeezer A from vertical direction
Extruding optical fiber, piezoelectricity squeezer B extrudes optical fiber from 45 degree of angular direction extruding optical fiber, piezoelectricity squeezer C from vertical direction, and piezoelectricity is squeezed
Depressor D extrudes optical fiber from 45 degree of angular direction.
The round complex plane effect of piezoelectricity squeezer control polarization state is as shown in figure 4, when 0 degree of angular direction extrudes in Fig. 3 in Fig. 3
Polarization state develops along the linear axis of S1 in Fig. 4, and linear axis when 45 degree of angular direction extrude in Fig. 3 along S2 in Fig. 4 develop.Example
Such as, in order to polarization state A in Fig. 4 is changed into polarization state C, it is necessary to change 45 degree of piezoelectric ceramics of deflection (B in Fig. 3) extruding electricity
Pressure, makes polarization state be evolved into polarization state B, then changes 0 degree of extruding voltage of deflection piezoelectric ceramics (A in Fig. 3), makes polarization state
It is evolved into polarization state C.As shown in Figure 4, by the 0 degree and 45 degree extruding in direction, any point can be by rotating to up to separately
Outward a bit, it is to prevent the generation at dead angle using four squeezers.
For double Mach-Zehnder fiber optic interferometric systems over long distances, because optical fiber link is very long, the stress of optical fiber is very not
Uniformly, interference light intensity change is random caused by the change of polarization state.Light can not possibly be allowed substantially with ordinary optic fibre in optical fiber
Middle transmission is without producing polarization state change, or even produces fixed polarization state change to be all difficult.For this present invention selection avoid by
Polarization state regulation is to fixed angle in optical fiber, but by feedback, allows the polarization state ψ 2 for entering interference region counterclockwise, with
The polarization state ψ 1 into interference region is consistent clockwise.Due to the symmetry of double M-Z light paths, two-way detector is now obtained
Optical signal be consistent so that ensure positioning accuracy.
By the light path after improvement as shown in figure 5, Polarization Controller 25 is added on the time delay arm 29 of light path, (near laser
One end of device 20, is easy to implement the control to Polarization Controller 25).The light that laser 20 sends is divided into two-way through coupler C3,
Clockwise light through isolator 23 (prevent clockwise, the two-way light of counterclockwise transmission form Sagnac and interfere), into dry
Relate to area 30, if into interference region polarization state for marked as 21, anticlockwise light is through coupler C4, polarization control in the figures of ψ 1
Device processed 25, into interference region 30, if into interference region light in the figures of polarization state ψ 2 marked as 26.Anticlockwise optical transport
(tens kilometers) more long to the link of interference region 30, due to the effect such as temperature stress on the way, polarization state ψ 2 and polarization state ψ 1 has phase
Difference, this phase difference causes the correlation of subsequent intervention light very poor, by the voltage for adjusting Polarization Controller 25, thus it is possible to vary partially
Polarization state ψ 2, makes polarization state ψ 2 be consistent with polarization state ψ 1.So clockwise light is divided into interference region through coupler C1
Two-way, interferes that (interference signal carries disturbing in interfere arm through 27 interfere arms and 28 reference arms at coupler C2 respectively
Dynamic signal, marked as R in figure), anticlockwise light is divided into two-way in interference region through coupler C2, respectively through 27 interfere arms and
28 reference arms interfere (disturbing signal that interference signal is carried in interfere arm, marked as R in figure) at coupler C1, by
Consistent in the suitable backlight polarization state for entering interference region, the light path that the light in the direction of interference region two passes through is reversible, by light path
Invertibity is known, in the interference of light point C2 clockwise and interference of light counterclockwise point C1, the light phase of interfere arm and pickup arm keeps respectively
Unanimously, so interference signal out can keep correlation very high.Clockwise light is through pickup arm 29 in coupler
Detected by detector 2 (marked as 24 in figure) through light splitting at C4, anticlockwise light is at the C1 that interference is gone through light splitting quilt
Detector 1 (marked as 22 in figure) is detected.
The algorithm for realizing the regulations of polarization state ψ 2 is full search algorithm, and concrete principle is：Due to the beat frequency phenomenon of light wave, when
When whole interference system does not have vibration signal, two-way interference signal has a carrier wave for low frequency, when the polarization of two-way interference light
When state is inconsistent, the carrier wave of this low frequency is also inconsistent.So with the difference of this two paths of signals, (i.e. two detectors are detected
Voltage difference) as feedback signal, with full search algorithm, by controlling Polarization Controller input voltage, realize that two enter dry
The polarization state for relating to area's light is consistent.
By the regulation of Polarization Controller, the phase of two paths of signals in optical interference circuit can be made identical, so that two-way is interfered
The intensity (light intensity) of signal is only related with oscillation intensity.After being transmitted through long-distance due to two-way interference signal, phase becomes at random
Changing will cause polarization state inconsistent again, the voltage difference that the detector of this method monitor in real time two is detected as feedback signal, in real time
Keep two-way consistent into the polarization state of interference region light.The good correlation of light good general's real-time ensuring that so detector is detected
Property, the delay inequality for reflecting vibration signal that the delay inequality of light intensity can be good.Vibration is calculated by accurate acquisition system
The delay inequality of signal, it is possible to realize positioning function of double Mach-Zehnder fiber optic interferometrics systems to vibration signal over long distances.
There is advantages below using such scheme：
1st, signal coherency present in double Mach-Zehnder fiber optic interferometric systems over long distances is solved poor, it is impossible to be used for
The problem of vibration signal positioning.
2nd, by the polarization state of time delay arm in automatically controlled piezoelectric ceramics real-time control optical interference circuit, detected with two detectors
Voltage difference realizes the regulation of polarization state as feedback signal --- implementation method is simple, and control circuit, software algorithm are simply easy
OK, and easily realize automatically adjusting in real time.
3rd, realize positioning using general single mode fiber, solve the problems, such as using polarization maintaining optical fibre high cost.
It should be appreciated that for those of ordinary skills, can according to the above description be improved or converted,
And all these modifications and variations should all belong to the protection domain of appended claims of the present invention.
Claims (1)
1. a kind of pair of interference signal correlation adjusting method of Mach-Zehnder fiber optic interferometric systems, it is characterised in that including:
Four piezoelectricity squeezers being made up of piezoelectric ceramics, into 45 degree of angle extruding optical fiber on each action direction, form Polarization Controller,
The Polarization Controller is added on the time delay arm of light path and is proximate to one end of laser；By feedback, allow and enter counterclockwise dry
The polarization state in area is related to, is consistent with the polarization state clockwise into interference region；The Polarization Controller is by four direction
Piezoelectric ceramics is constituted, by the polarization state for controlling the voltage at each Polarization Controller the two poles of the earth to realize counterclockwise into interference region light
Omnirange changes without dead angle；The deformation quantity of the piezoelectric ceramics is related to the voltage at piezoelectric ceramics the two poles of the earth is supplied to, by changing
Control voltage changes the deformation quantity of all directions, and then changes the deformation quantity that piezoelectric ceramics extrudes optical fiber；To enter counterclockwise
The polarization state regulation of interference region is consistent with the polarization state regulation for entering interference region clockwise, counterclockwise and clockwise for allowing
The interference signal of generation keeps good correlation；There is low frequency in the interference signal for producing counterclockwise and clockwise
Carrier wave, when the polarization state of two-way interference light is inconsistent, the voltage difference that two detectors are detected is searched as feedback signal with the overall situation
Rope algorithm, by controlling Polarization Controller input voltage, realizes that the polarization state for entering interference region light counterclockwise and clockwise keeps
Unanimously.
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| CN105300507B (en) * | 2015-10-26 | 2018-08-28 | 南京航空航天大学 | Optical fibre vibration sensor and its M-Z pickup arm light channel structures |
| CN110119041A (en) * | 2018-02-07 | 2019-08-13 | 桂林电子科技大学 | Piezoelectric ceramics microarray polarization type optical fiber acousto-optic device |
| CN110119039A (en) * | 2018-02-07 | 2019-08-13 | 桂林电子科技大学 | Spiral microarray format modulation type optical fiber vortex field generator |
| CN110119043A (en) * | 2018-02-07 | 2019-08-13 | 桂林电子科技大学 | Fiber polarization controller based on cross-polarization type piezoelectric ceramics microarray |
| CN113108710B (en) * | 2021-04-14 | 2022-05-03 | 安徽大学 | Optical low-frequency strain detection system and detection method based on ellipse fitting |
| CN117848483A (en) * | 2024-02-26 | 2024-04-09 | 广州杰鑫科技股份有限公司 | Optical fiber vibration sensing system, optical fiber vibration sensing method and optical cable line inspection analyzer |
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| CN101344452A (en) * | 2008-08-22 | 2009-01-14 | 北京交通大学 | Method and device for implementing polarization sensitive optical time domain reflection technology by using piezoelectric ceramic |
| CN101526374A (en) * | 2009-02-13 | 2009-09-09 | 上海大学 | Full optical-fiber Mach-Zehnder interferometer of polarization fading and polarization phase-position noise resistance |
| CN102291181A (en) * | 2011-08-09 | 2011-12-21 | 天津大学 | Polarization control method and system of distributed optical fiber disturbance positioning system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101344452A (en) * | 2008-08-22 | 2009-01-14 | 北京交通大学 | Method and device for implementing polarization sensitive optical time domain reflection technology by using piezoelectric ceramic |
| CN101526374A (en) * | 2009-02-13 | 2009-09-09 | 上海大学 | Full optical-fiber Mach-Zehnder interferometer of polarization fading and polarization phase-position noise resistance |
| CN102291181A (en) * | 2011-08-09 | 2011-12-21 | 天津大学 | Polarization control method and system of distributed optical fiber disturbance positioning system |
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