CN101995265A - Low coherence multiplex optical fiber interferometer based on non-balanced Mach-Zehnder optical autocorrelator - Google Patents
Low coherence multiplex optical fiber interferometer based on non-balanced Mach-Zehnder optical autocorrelator Download PDFInfo
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Abstract
The invention provides a low coherence multiplex optical fiber interferometer based on a non-balanced Mach-Zehnder optical autocorrelator. The optical fiber interferometer is formed by successively connecting a wide-spectrum light source (1), the non-balanced Mach-Zehnder optical autocorrelator (2), an optical distance autocorrelation detection unit (3), a transmission optical fiber (4) and an optical fiber sensor array (5) from end to end, wherein the non-balanced Mach-Zehnder optical autocorrelator (2) is composed of a first optical fiber coupler (21), a three-port optical circulator (23), an optical fiber collimator (24), a moveable optical reflector (25) and a second optical fiber coupler (26); and the optical distance autocorrelation detection unit (3) is composed of a three-port optical circulator (31) or (33), a photodetector (32) or (34). The optical fiber interferometer can be applied to the fields such as real-time monitoring and measurement of multipoint strain or temperature and other physical quantities, monitoring of large-sized intelligent structures and the like.
Description
Technical field
The invention belongs to the optical fiber technology field, be specifically related to a kind of low relevant multiplex fibre optic interferometer based on Mach-Zehnder optics autocorrelator, purpose be solve sensor when multiplexed secondary light path coherent noise suppress, the light source utilization ratio is crossed low and is increased problem such as system stability.
Background technology
Adopt low relevant, broad spectrum light source, for example the fibre optic interferometer of light emitting diode (LED), super spontaneous radiation light source (ASE) or superradiance laser diode (SLD) driving is commonly called the white light fibre optic interferometer.Typical its structure of optical fiber white light interference instrument as shown in Figure 1, adopt wide spectrum light source LED or ASE as light source in the Michelson formula interferometer of building by single-mode fiber, realize measurement measured physical quantity by the white-light fringe that detector detected.Its principle of work is as follows, after the wide range light that is sent by low relevant wide spectrum light source 11 enters single-mode fiber, be divided into two bundles by 3dB single-mode fiber 2 * 2 coupling mechanisms 13, a branch of light enters the single-mode fiber 14 that is used as gage beam, optical reflection face 15 reflection backs by its rear end are returned along former road, arrive photodetector 12 through single-mode fiber 14, coupling mechanism 13, this Shu Guang is called measuring-signal light; Send light by light source 11 and be coupled device 13 other a branch of light along separate routes, enter as single mode and connect optical fiber 16, GRIN Lens 17 with reference to arm, arrive photodetector 12 through returning along former road equally after the reflection of mobile mirror 18, this Shu Guang is called as reference signal light.Measuring-signal light and reference signal light are in detector surface generation coherence stack, because the coherent length of wide spectrum light source is very short, be approximately several microns to tens microns, have only when reference signal light and measuring-signal optical path difference during less than the coherent length of light source, just can produce coherence stack, output white light interference pattern (referring to accompanying drawing 2).
As shown in Figure 2, the feature of white-light fringe is that a principal maximum is arranged, and is called the center striped, and it is corresponding for it with zero optical path difference, and during promptly corresponding to reference beam and measuring beam equivalent optical path, the light path that is called reference beam and measuring beam is complementary.When the gage beam change in optical path length, by changing the retardation of fibre delay line, the light path of reference signal is changed, can obtain the center interference fringe.The position of center striped provides a reliable absolute position reference for measurement, when its light path changes under the influence of measuring beam at extraneous measured physical quantity, only need the change in location of the white-light fringe that can obtain, thereby obtain the absolute change value of measured physics amount by the adjustment of reference arm light path.Compare with other fibre optic interferometers, optical fiber white light interference is except having advantages such as high sensitivity, essential safety, anti-electromagnetic field interference, and maximum characteristics are to carry out absolute measurement to pressure, strain, temperature etc. are to be measured.Therefore the white light interference fibre optic interferometer is widely used in the measurement of physical quantity, mechanical quantity, environment parameter, chemistry amount, biomedical amount.
Be to solve the multiplexed problem of Fibre Optical Sensor, nineteen ninety-five U.S. H-P Wayne V.Sorin of company and Douglas M.Baney disclose a kind of multiplexing method (United States Patent (USP): the patent No. 5557400) of the white light interference sensor based on the optics autocorrelator.As shown in Figure 3, it is based on non-equilibrium Michelson interferometer structure, utilize the coupling of light signal between the optical path difference of former and later two end face reflection light signals of optical path difference that forms between Michlson interferometer fixed arm and the variable sweep arm and multiplexing fiber-optic sensor to realize the optics auto-correlation, obtain the white light interference signal peak of sensor, utilize again and change light path extent between scan arm and the fixed arm, mate one by one with the length of each sensor in a plurality of end to end serial fibre optic sensor arras, finish the multiplexed of Fibre Optical Sensor.Though said structure is the multiplexed classical architecture of white light interference optical fiber sensing device, its shortcoming mainly contains two: first light source power efficient is low, and it is in 1/4 the optical power sensor that equivalence is only arranged; It two is that being sent in the flashlight feedback meeting light source by light source of a half-power arranged, for the light source of ASE as not isolating the stability that can influence system works.
Except that said structure, the applicant in 2007 and 2008 disclosed low relevant strand 200710072350.9) and space division multiplexing Mach-Zehnder cascade type optical fiber interferometer and measuring method (Chinese patent application number: 200810136824.6) be mainly used to solve the problem of the anti-breaking-up in the fibre optic sensor arra laying process turn round formula class Sagnac optical-fiber deformation sensor (Chinese patent application number:; The applicant in the composite instrument of disclosed optical fiber Mach-Zehnder in 2008 and Michelson interferometer array (Chinese patent application number: 200810136819.5) and twin array Michelson optical fiber white light interference strain gage (Chinese patent application number: 200810136820.8) be mainly used in solve the white light fibre optic interferometer multiplexed in temperature disturb and temperature and strain while problems of measurement to measuring; The applicant is disclosed a kind of simplifying type multiplexing white light interference optical fiber sensing demodulating equipment (Chinese patent application number: 200810136826.5) with based on the distributed optical fiber white light interference sensor array of adjustable Fabry-Perot resonant cavity (Chinese patent application number: 200810136833.5) in 2008, the introducing of ring cavity, F-P chamber light path autocorrelator, be mainly used in the structure of simplifying multiplexed interferometer, structure is light channel structure altogether, improves temperature stability; The applicant in 2008 disclosed a kind of double-datum length low coherent optical fiber ring network apparatus for sensing demodulating (Chinese patent application number: 200810136821.2) based on the introducing of 4 * 4 fiber coupler light path autocorrelators, purpose is problems of measurement when solving many reference sensors.In the above-mentioned interferometer structure based on space division multiplexing, the light path autocorrelator adopts structures such as Michelson interferometer, Mach-Zehnder interferometer, Fabry-Perot interferometer mostly, in order to form the signal beams with certain optical path difference (more than at least two bundles) that can be complementary with Fibre Optical Sensor front/rear end reflected signal optical path difference, at least one N * M fiber coupler in the light path autocorrelator (for example: 2 * 2,3 * 3 or 4 * 4 fiber couplers).Because the dichroism and the light path symmetry characteristic of N * M fiber coupler, there are three problems without exception in above-mentioned optics autocorrelator: first light path topological structure is big to the light source power decay, the light source utilization factor is low.To adopt 2 * 2 fiber couplers is example, the light signal that is taken place by light source only has half to reach sensor array, by the light signal of its reflection, half is arranged through overdamping again, with the disclosed light channel structure of W.V.Sorin shown in Figure 3, have only 1/4 light source power participation optical correlation process in theory at most, other power all have been attenuated, if adopt 3 * 3 or 4 * 4 fiber couplers, then its power attenuation is (1/3)
2Or (1/4)
2, then even more serious; It two is some light channel structure, twice (perhaps repeatedly) is through the light path autocorrelator before and after the light signal, as: Chinese patent application numbers 200810136826.5,200810136833.5 and a kind of double-datum length low coherent optical fiber ring network apparatus for sensing demodulating (Chinese patent application number: 200810136821.2), make that light signal between Fibre Optical Sensor and the light path autocorrelator is relevant to exist plural light path matching relationship, cause and have secondary (perhaps repeatedly) light path coupling noise in the white light interference signal, make sensor auto-correlation peak value no longer unique on the locus, its identification and sensor measurement are caused difficulty; It three is to have symmetry on the light path topological structure, light source and detector are symmetry and reciprocity in light path, have at least in theory and feed back in the light source again with the light signal of the identical numerical value of detector received power, though the type of light source is a wide range light, compare with LASER Light Source, very inresponsive to feedback, but excessive signal power feedback, can cause the resonance (as based on light source ASE of the spontaneous superradiance type of optical fiber etc.) of light source, can cause the power of light source generation light signal to reduce, particularly when white light interference, bigger interference signal power swing can cause extremely adverse influence to the use of light source, reduces the measuring accuracy of optics from relevant peak amplitude.
Summary of the invention
The object of the present invention is to provide a kind of light unidirectional transmission property that has, flashlight can't feed back in the light source, can increase the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator of the stability of system.
The object of the present invention is achieved like this:
It comprises wide range (ASE) light source 1, non-equilibrium Mach-Zehnder optics autocorrelator 2, light path auto-correlation probe unit 3, Transmission Fibers 4 and fibre optic sensor arra 5; Non-equilibrium Mach-Zehnder optics autocorrelator 2 is made up of first fiber coupler 21, three port photocirculator I 23, optical fiber collimator 24, removable optical mirror 25 and second fiber coupler 26; Light path auto-correlation probe unit 3 is made up of three port photocirculator II31, photo-detector 32; First fiber coupler 21 has an optical input signals end and two optical output signal ends at least, second fiber coupler 26 have two optical input signals ends and two optical output signal ends at least; The optical input signals end of first fiber coupler 21 connects wide spectrum light source; Two optical output signal ends of first fiber coupler 21, two optical input signals ends of second fiber coupler 26, two ports of three port photocirculator I23 connect in the form of a ring; The another port of three port photocirculator I23 is connected with optical fiber collimator 24; At least one optical output signal end of second fiber coupler 26 connects Transmission Fibers 4; Transmission Fibers 4 connects fibre optic sensor arra 5.
The present invention can also comprise:
1, described second fiber coupler has two optical output signal ends, light path auto-correlation probe unit of two optical output signal end difference, and each light path auto-correlation probe unit connects fibre optic sensor arra by Transmission Fibers respectively.
2, described Optical Fiber Sensing Array is made up of several head and the tail Fibre Optical Sensor of serial connection successively, and the single-mode fiber that Fibre Optical Sensor is any by a segment length, two ends have fiber stub is formed a series of single-mode fiber sections that are uneven in length and constituted end to end serial array.
3, the splitting ratio of the optical output signal end of described first fiber coupler is adjusted between 1%～99%.
4, described three port photocirculators 23,31,33 have an optics input end c, an optics output terminal d and an optical reflection end f, it has the optical-unidirectional transfer function, injecting light signal by input end c is only exported by output terminal d, inject light signal by output terminal d, then only export by reflection end f.
5, described non-equilibrium Mach-Zehnder optics autocorrelator 2 is first fiber couplers 21 two optics output terminals are connected respectively at the input end c of optical circulator I23 and the input end g of second coupling mechanism 26; The output terminal d of three port photocirculator I23 is connected with optical fiber collimator 24; An optics input port of the reflector port f of three port photocirculator I23 and second coupling mechanism 26 links; The flashlight that is sent by wide spectrum light source 1 is divided into two bundles through first fiber coupler 21, a branch of optical signals first fiber coupler 21 output port b are exported by output port through second coupling mechanism 26 through the fixed arm 22 of Mach-Zehnder interferometer, enter the input end h of light path auto-correlation probe unit 3; The another one output port of a branch of in addition optical signals first coupling mechanism 21, input port c through three port photocirculator I23, by output port d after optical fiber collimator 24 outgoing, quilt movably optical mirror 25 returns, and exports via the reflector port f of three port photocirculator I23 and the output port of second fiber coupler 26.Have certain optical path difference between the two beam signal light that separated by first coupling mechanism 21, its numerical values recited can change by the distance that changes between optical fiber collimator 24 and the removable optical mirror 25; The two-beam signal has unidirectional transmission property, does not or else turn back in the light source.
6, described light path auto-correlation probe unit 3 has unidirectional transmission property, and the two bundle flashlights that come from non-equilibrium Mach-Zehnder optics autocorrelator 2 are transmission and not returning forward only; They are through input end h, the k of three port photocirculators 31,33, only export by output port i, l, arrive fibre optic sensor arra 5 by Transmission Fibers 4, after the Fibre Optical Sensor reflection that carries physical message to be measured, through output port i, the l input of Transmission Fibers 4, reflector port j, m output is only arranged once more, arrive photodetector 32,33 by optical circulator 31,33, through after the opto-electronic conversion, obtain the measurement information for the treatment of of white light interference signal and sensor thereof.
7, described optical fibre device all is operated in the single mode state.
The present invention adopts non-equilibrium Mach-Zehnder interferometer, by means of the optical path delay of being introduced between two non-equilibrium arms, generates the adjustable inquiry light beam of two-beam path difference; Make the light signal that sends by light source only have the characteristic of fl transmission by in light path, introducing optical circulator, avoided twice (perhaps repeatedly), suppressed secondary (repeatedly) the light path coupling interaction noise that causes by the light path autocorrelator; Because light path does not have unnecessary beam splitter, and except that the optical power attenuation that device loss causes, the power of light source all reaches detection array, the signal power that is reflected by sensor array also all arrives detector, has strengthened the utilization ratio of light source greatly simultaneously; The another one effect of the fl transmission characteristic of light path is to have eliminated the feedback light of light source.The invention solves Fibre Optical Sensor when multiplexed, the light source utilization factor is low, has the problem of secondary light path coupling noise and light source feedback light, has increased the measuring accuracy and the stability of system.
The ultimate principle of the inventive method is based on hangs down principle of interference and space division multiplexing principle relevant, wide range light (white light).Based on the interfere type optical fiber white light strain transducer structure of non-equilibrium Mach-Zehnder optics autocorrelator as shown in Figure 4, promptly only connect the situation of a sensor 51 in the sensor array.The outgoing beam of low relevant wide spectrum light source 1 is divided into two bundles by first fiber coupler 21, a branch of flashlight is through the fixed arm 22 of Mach-Zehnder interferometer, directly output to the light path correlation detection unit 3 from the output port of second fiber coupler 26, a branch of in addition flashlight enters the input port b of optical circulator 23 through the output port of first fiber coupler 21, arrive delivery outlet d via input port b end, enter optical fiber collimator 24, and after mirror 25 reflections that are reflected, once more by the incident of d port, export from the f port, the light path that outputs to light path correlation detection unit 3, two light beams through second fiber coupler is as follows:
(1) transmitted light beam of the fixed arm of the nonequilibrium Mach-Zehnder interferometer of process:
a-＞b-＞g-＞h；
(2) transmitted light beam of the scan arm of the nonequilibrium Mach-Zehnder interferometer of process:
a-＞c-＞d-＞e-＞f-＞h；
Hence one can see that: differ fixing optical path difference (c-＞d-＞e-＞f-＞b-＞g), just be the optical path difference of Mach-Zehnder interferometer two arms between two light beams.
Two light beams are via the incident port h of the optical circulator 31 in the light path auto-correlation probe unit 3, only enter Transmission Fibers 4 from exit ports i, by the left side of Fibre Optical Sensor 51 reflection end face l and right reflection end face m reflection, arrive optical circulator 31 via Transmission Fibers 4 once more, only from port j outgoing, reach photodetector 32 through port i.
Have certain optical path difference inquiry light beam that equates from two bundles of non-equilibrium Mach-Zehnder optics autocorrelator 2 outgoing, reflected, cause static light path difference (when no strain loads) l-＞m equally by two end faces about Fibre Optical Sensor.For for the flashlight of optics autocorrelator 2 outgoing, by this section light path h-＞i-＞l-＞i-＞j between light path correlation detection unit 3 and the Transmission Fibers 4 is to be total to light path, therefore when carrying out the optics auto-correlation, can ignore, cause the l-that the only limits to sensor 51＞m end of additional optical path difference.When c-＞d-＞e-＞f-＞b-＞g and l-＞m when equating, can be by the accurately coupling that moves of scanning reflection mirror 23, make its two equate (l-＞m=c-＞d-＞e-＞f-＞b-＞g) fully, promptly, compensated by non-equilibrium Mach-Zehnder optics autocorrelator 2 fully by the two bundle optical path differences that flashlight had of Fibre Optical Sensor 51 left and right sides end face reflections.At this moment, the reflected signal of two end faces produces and interferes about Fibre Optical Sensor, coherence stack takes place on detector 32 surfaces, because the coherent length of wide range low-coherence light source is very short, be approximately several microns to tens microns, have only when the optical path difference of interference signal during, just can produce coherence stack, output white light interference pattern less than the coherent length of light source.
In the formula: I
1, I
2Be the signal intensity of reference beam and measuring beam, k is a wave number, and x is two interference signal optical path differences, and φ is an initial phase, and γ (x) is the light source autocorrelation function.
Specific to the optical fiber measurement system of Fig. 4, be measuring-signal and equate in the optical path difference of introducing between annular multiple beam maker catoptron 23 and the optical fiber collimator in light path that sensor 51 left and right sides end face reflections are accumulated and reference signal.
(nL
1+2X)-nL
2-＝2nl (2)
Wherein, l is the length of the Fibre Optical Sensor between the reflecting surface of the left and right sides, and n is the refractive index of fiber core, and X represents optical fiber collimator 24 to the distance between the catoptron 25, nL
1Be the light path of c-＞d-＞e-＞f, nL
2Light path for b-＞g.
As the above analysis:
(1) behind the non-equilibrium Mach-Zehnder optics of the process autocorrelator 2 and light path auto-correlation probe unit 3, Transmission Fibers 4 and sensor 51 of the flashlight that sends by light source, return light path auto-correlation probe unit 3, promptly light transmission path be a-＞b-＞g (h-＞i-＞l (m) of c-＞d-＞e-＞d-＞f)-＞i-＞j; Because the existence of optical circulator 22 and 31 makes light path have unidirectional transmission property, flashlight can't be got back to light source, has avoided the light feedback to cause the instability of light source.
(2) only produce the inquiry light beam that two bundles have certain optical path difference by non-equilibrium Mach-Zehnder optics autocorrelator 2, and because the unidirectional transmission property of light path, only through an optics autocorrelator 2, therefore when they and the caused optical path difference of sensor are complementary, can only cause an autocorrelation signal peak, suppress secondary light path coupling interaction noise.
(3) because the transmissison characteristic of Mach-Zehnder optics autocorrelator 2 and the unidirectional transmission property of light path auto-correlation probe unit 3, and there are not other unnecessary beam splitters in the light path, make by light source and send the flashlight that is reflected by Fibre Optical Sensor, full entry interventional procedures, greatly increased the interference signal light intensity.Light path topological structure disclosed by the invention is the present known the highest a kind of light path of light source utilization ratio.According to the optical interference signals etection theory as can be known: the enhancing of luminous power can be optimized the signal to noise ratio (S/N ratio) of interference signal, strengthens the accuracy of detection of interference system; Perhaps reduce the requirement of system, reduce the complicacy and the cost of system light source power.
Only occur near the light path coupling several microns between tens microns based on the interference fringe of the fibre optic interferometer of white light interference principle.Utilize this characteristics, need not to utilize complicated time-division or frequency multiplexing technique, can realize the multiplexing of sensor, as shown in Figure 5.With Fibre Optical Sensor 51 end to end composition serial array 5, as shown in Figure 6.The end face of each sensor 503 all has certain reflectivity.If the length of each sensor is greater than the coherent length of light source, then only there is single white light interference signal in interference fringe in coherent length separately, and promptly interference fringe is not disturbed mutually, and is separate; But by adjusting implementation space light path scanning to the scanning reflection mirror 25 in the non-equilibrium Mach-Zehnder optics autocorrelator 2, if the length of each sensor is not simultaneously, just can be distinguished a plurality of sensors, thereby realize to the inquiry of a plurality of external physical quantity with inquire, can realize very easily that distributed sensing measures.
By as seen above-mentioned, multiplexed and basic thought demodulation of distributed optical fiber white light interference sensor array is when being compensated by the variable light path difference that produces in the non-equilibrium Mach-Zehnder optics autocorrelator 2 by the optical path difference that sensor is introduced, light path coupling one to one takes place, make the white-light fringe of generation separate on the light path scanning space, do not disturb mutually, thereby realize the distributed sensing measurement.
As sensor l
jWhen being subjected to extraneous factor effect generation deformation such as strain, regulate variable parameter X
j, make the light path coupling, that is:
ΔX
j＝Δnl
j j＝1，2，3，... (3)
Suppose that Fibre Optical Sensor length is by l
1Change to l
1+ Δ l
1, second sensor is by l
2Change to l
2+ Δ l
2, N sensor is by l
NChange to l
N+ Δ l
N,, then can obtain the strain of each sensor institute perception by the variable quantity of survey sensor length
Light path autocorrelator and light path auto-correlation probe unit have all adopted the optics circulator with unidirectional transmission property among the present invention, make it have following advantage and characteristics are:
(1) except that the optical power attenuation that device loss causes, the power of light source all reaches detection array, and the signal power by the sensor array reflection also all arrives detector, when using same light source, even consider the decay of optical circulator, also be that the power that reaches detector doubles at least, greatly improved the utilization factor of light source.Light path topological structure disclosed by the invention is the present known the highest a kind of light path of light source utilization ratio.
(2) make the light signal that sends by light source only have the characteristic of fl transmission by in light path, introducing optical circulator, avoided twice (perhaps repeatedly), suppressed secondary (repeatedly) the light path coupling interaction noise that causes by the light path autocorrelator;
(3) because light signal can't be got back in the light source, avoided the light beam feedback, increased the stability of light-source system, the accuracy of signal measurement is provided.
In addition, its advantage and characteristic of also having is:
(4) the distributed optical fiber white light interference sensor system of the non-equilibrium Mach-Zehnder interferometer of employing, need not to adopt complicated time division multiplex or frequency multiplexing technique, only need by continuous space light path scanning, can realize inquiring and measuring to a plurality of sensor signals, technology is simple, is easy to realize.
(5) distributed optical fiber white light interference sensor array of the present invention's structure, can realize the array that Fibre Optical Sensor is laid, each sensor is independent of each other when measuring, sensor length can be determined by the user, its length can be selected arbitrarily in hundreds of rice scope from several centimetres, has the ability of multitask sensing, multi-sensor, local train sensing and large scale deformation sensing.
Description of drawings
Fig. 1 is typical white light interference Michelson interferometer structure synoptic diagram.
Fig. 2 is typical white-light fringe signal schematic representation.
Fig. 3 is based on the multiplexed light channel structure synoptic diagram of Fibre Optical Sensor of non-equilibrium Michelson interferometer structure light path autocorrelator.
Fig. 4 is based on the light channel structure synoptic diagram of the fibre optic interferometer connection single-sensor of non-equilibrium Mach-Zehnder interferometer structure light path autocorrelator.
Fig. 5 is the light path synoptic diagram of the fibre optic interferometer of non-equilibrium Mach-Zehnder interferometer structure light path autocorrelator when multiplexed.
Fig. 6 is based on the multi-channel optical fibre sensor construction connection diagram of photoswitch.
Fig. 7 is the structural representation of end to end serial topological structure fibre optic sensor arra.
Embodiment
For example the present invention is done description in more detail below in conjunction with accompanying drawing:
Based on a kind of scheme that is used for the distributing optical fiber sensing measuring system of non-equilibrium Mach-Zehnder structure optics autocorrelator, as shown in Figure 5.As shown in Figure 5, this distributed optical fiber white light interference sensor array is connected successively by wide spectrum light source 1, non-equilibrium Mach-Zehnder optics autocorrelator 2, light path auto-correlation probe unit 3, Transmission Fibers 4, fibre optic sensor arra 5 head and the tail and constitutes.Non-equilibrium Mach-Zehnder optics autocorrelator 2 is made up of first fiber coupler 21, three port photocirculators 23, optical fiber collimator 24, removable optical mirror 25 and second fiber coupler 26; Light path auto-correlation probe unit 3 is made up of three port photocirculators 31,33 and photo- detector 32,34.
As shown in Figure 5.During the strain sensing system works, the flashlight that sends by wide spectrum light source 1, be divided into two bundles by first fiber coupler 21 in the non-equilibrium Mach-Zehnder optics autocorrelator 2, the a branch of fixed arm 22 and second fiber coupler 26 through interferometer directly outputs in the light path correlation detection unit 3, a branch of in addition other arm through first coupling mechanism is input among the input port c of optical circulator 23, arrive delivery outlet d via input port c end, enter optical fiber collimator 24, and after mirror 25 reflections that are reflected, once more by the incident of d port, from the output of f port,, output in the light path correlation detection unit 3 via second fiber coupler 26.Above-mentioned two-beam is via the incident port h of the optical circulator 31 in the light path auto-correlation probe unit 3, only enter Transmission Fibers 4 from exit ports i, by the forward and backward reflection end face reflection of each sensor 51 in the fibre optic sensor arra 5, arrive optical circulator 31 via Transmission Fibers 4 once more, only from port j outgoing, reach photodetector 32 through port i; The output terminal of second fiber coupler can connect other a branch of Fibre Optical Sensor, its its light path analytical approach and aforementioned similar, and ben is different with the topological structure of Fig. 3, array R
10～R
1nWith R
10～R
1nOwing to isolated mutually by optical circulator 31 and 33 and adopt two detectors to survey optics respectively from relevant peak signal, so the no longer phase mutual interference of the two light signal, this also is the structure of the present invention another one outstanding feature compared of pre-structure with it; Be without loss of generality, as shown in Figure 6, can after light path auto-correlation probe unit 3, increase multichannel photoswitch 6, connect the more optical fiber sensor array, also second coupling mechanism can be replaced with 2 * N coupling mechanism or multi-channel optical fibre switch, connect the Optical Fiber Sensing Array on N road.When the variable light path difference that produces in by non-equilibrium Mach-Zehnder optics autocorrelator 2 when optical path difference that sensor is introduced compensates, detector will receive the peak value of the AC signal that is produced by interference, dynamic scan by light path, peak value to interference signal carries out tracking measurement, can obtain the information of sensor length change amount in real time.But follow the tracks of by continuous adjustment implementation space light path scanning to distance between optical fiber collimator 24 and the catoptron 25, because the length of each Fibre Optical Sensor is all different, therefore can be distinguished a plurality of sensors, thus the inquiry that realizes a plurality of external physical quantity with inquire.
Fibre Optical Sensor 51 is to be made of the fiber segment perpendicular to one section random length of fiber end face that two ends have certain reflectivity, typical structure as shown in Figure 7, each Fibre Optical Sensor constitutes (it is long to get 1000mm as sensor length) by the single-mode fiber 504 of same length, and two ends install ceramic insertion core 501 additional, end face is through after the polishing, obtains perpendicular to the reflectivity of transmission light direction more than or equal to 1% fiber end face.Fibre Optical Sensor 51 can be connected with sensor or optical fiber by porcelain bushing 502, and porcelain bushing plays the protective effect to the sensor end face simultaneously.Formed the optical reflection face 503 of an optical reflectivity 1%～3% between the fiber stub that two are utilized ferrule to connect.Several Fibre Optical Sensor 51 end to end fibre optic sensor arras 5 that just form a serial.
Claims (9)
1. the low relevant multiplex fibre optic interferometer of a non-equilibrium Mach-Zehnder optics autocorrelator is characterized in that: comprise wide spectrum light source (1), non-equilibrium Mach-Zehnder optics autocorrelator (2), light path auto-correlation probe unit (3), Transmission Fibers (4) and fibre optic sensor arra (5); Non-equilibrium Mach-Zehnder optics autocorrelator (2) is made up of first fiber coupler (21), three port photocirculator I (23), optical fiber collimator (24), removable optical mirror (25) and second fiber coupler (26); Light path auto-correlation probe unit (3) is made up of three port photocirculator II (31), photo-detector (32); First fiber coupler (21) has an optical input signals end and two optical output signal ends at least, second fiber coupler (26) have two optical input signals ends and two optical output signal ends at least; The optical input signals end of first fiber coupler (21) connects wide spectrum light source; Two optical output signal ends of first fiber coupler (21), two optical input signals ends of second fiber coupler (26), two ports of three port photocirculator I (23) connect in the form of a ring; The another port of three port photocirculator I (23) is connected with optical fiber collimator (24); At least one optical output signal end of second fiber coupler (26) connects Transmission Fibers (4); Transmission Fibers (4) connects fibre optic sensor arra (5).
2. the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator according to claim 1, it is characterized in that: described second fiber coupler has two optical output signal ends, light path auto-correlation probe unit of two optical output signal end difference, each light path auto-correlation probe unit connects fibre optic sensor arra by Transmission Fibers respectively.
3. the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator according to claim 1 and 2, it is characterized in that: described Optical Fiber Sensing Array is made up of several head and the tail Fibre Optical Sensor of serial connection successively, and the single-mode fiber that Fibre Optical Sensor is any by a segment length, two ends have fiber stub is formed a series of single-mode fiber sections that are uneven in length and constituted end to end serial array.
4. the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator according to claim 1 and 2, it is characterized in that: the splitting ratio of the optical output signal end of described first fiber coupler is adjusted between 1%～99%.
5. the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator according to claim 3, it is characterized in that: the splitting ratio of the optical output signal end of described first fiber coupler is adjusted between 1%～99%.
6. the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator according to claim 1 and 2 is characterized in that: the multichannel photoswitch is set between light path auto-correlation probe unit and Transmission Fibers.
7. the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator according to claim 3 is characterized in that: the multichannel photoswitch is set between light path auto-correlation probe unit and Transmission Fibers.
8. the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator according to claim 4 is characterized in that: the multichannel photoswitch is set between light path auto-correlation probe unit and Transmission Fibers.
9. the low relevant multiplex fibre optic interferometer of non-equilibrium Mach-Zehnder optics autocorrelator according to claim 5 is characterized in that: the multichannel photoswitch is set between light path auto-correlation probe unit and Transmission Fibers.
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| CN102183866A (en) * | 2011-05-09 | 2011-09-14 | 哈尔滨工程大学 | Imbalanced-Mach-Zehnder-based demodulation device for multiplexing optical fiber interferometer |
| CN105021844A (en) * | 2015-07-27 | 2015-11-04 | 中国科学技术大学 | All-fiber wind measurement laser radar apparatus baed on asymmetric M-Z interferometer and method |
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| CN106959302A (en) * | 2017-04-11 | 2017-07-18 | 东华大学 | A kind of pile body integrity detection system and method based on low coherence interference technology |
| CN106959302B (en) * | 2017-04-11 | 2020-04-07 | 东华大学 | Pile body integrity detection system and method based on low coherence interference technology |
| CN107631814A (en) * | 2017-09-14 | 2018-01-26 | 电子科技大学 | Light senses light channel structure, frequency displacement change detecting method and sensing device from relevant |
| CN108592963A (en) * | 2018-03-29 | 2018-09-28 | 北京大学 | A kind of suppressing method and its system of time division multiplexing optical fiber sensing system multiplicative noise |
| CN108592963B (en) * | 2018-03-29 | 2020-06-26 | 北京大学 | Method and system for inhibiting multiplicative noise of time division multiplexing optical fiber sensing system |
| CN109163749A (en) * | 2018-09-30 | 2019-01-08 | 中国电子科技集团公司第三十四研究所 | A kind of non-equilibrium Fiber-M-Z interferometer, its adjust platform and production method |
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