CN101025845A - Perimeter defense optical fiber sensor - Google Patents
Perimeter defense optical fiber sensor Download PDFInfo
- Publication number
- CN101025845A CN101025845A CN 200710038259 CN200710038259A CN101025845A CN 101025845 A CN101025845 A CN 101025845A CN 200710038259 CN200710038259 CN 200710038259 CN 200710038259 A CN200710038259 A CN 200710038259A CN 101025845 A CN101025845 A CN 101025845A
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- fiber
- port
- detector
- optical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 71
- 230000007123 defense Effects 0.000 title abstract description 3
- 239000004065 semiconductor Substances 0.000 claims abstract description 5
- 239000000835 fiber Substances 0.000 claims description 88
- 230000003287 optical effect Effects 0.000 claims description 22
- 230000010287 polarization Effects 0.000 claims description 17
- 230000008901 benefit Effects 0.000 abstract description 5
- 238000009434 installation Methods 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 230000005540 biological transmission Effects 0.000 description 7
- 230000008878 coupling Effects 0.000 description 7
- 238000010168 coupling process Methods 0.000 description 7
- 238000005859 coupling reaction Methods 0.000 description 7
- 230000007246 mechanism Effects 0.000 description 7
- 238000005452 bending Methods 0.000 description 6
- 230000009545 invasion Effects 0.000 description 6
- 230000001681 protective effect Effects 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000006870 function Effects 0.000 description 3
- 230000008447 perception Effects 0.000 description 3
- 230000010363 phase shift Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010205 computational analysis Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000001687 destabilization Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 210000000056 organ Anatomy 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Images
Landscapes
- Length Measuring Devices By Optical Means (AREA)
Abstract
A perimeter defense optical fiber sensor for safety precaution is characterized by comprising a light source, a sensing optical fiber, an optical fiber coupler, a first detector, a second detector, a signal processor and an optical fiber circulator, wherein the light source is a semiconductor laser with a single longitudinal mode or a small number of longitudinal modes, the beam splitting ratio of the optical fiber coupler is 1: 1, two ends of the sensing optical fiber are respectively connected with two homodromous ports of the optical fiber coupler to form a Sagnac ring, and the position relations of the components are as follows: the output end of the light source is connected with the first port of the optical fiber circulator, the second port of the optical fiber circulator is connected with the second port of the optical fiber coupler, the first port of the optical fiber coupler is connected with the signal processor through the first detector, and the third port of the optical fiber circulator is connected with the signal processor through the second detector. The invention not only can find the external disturbance, but also can determine the position of the external disturbance, and has the advantages of low cost, simple system structure, convenient expansion and simple installation.
Description
Technical field
The present invention relates to safety precaution, particularly a kind of perimeter defence optical fiber sensor, it utilizes single-mode fiber when being subjected to external disturbance, the effect that the phase place of transmission light wave and polarization state etc. change, the invasion that detection takes place regional circumference, and determine the position that invasion takes place.The present invention is mainly used in the safety precaution in zones such as military establishment, confidential zone, museum, bank.
Background technology
The safety precaution of modern society is an important problem.Protect important areas such as government organs, military base, airport, weapons and ammunitions storehouse, prison, bank vault, museum, generating plant, oil depot, communications facility, harbour or even national boundaries effectively, anti-illegal-inbreak is vital.To such an extent as to be widely used in residential quarter, confidential zone such as technology such as camera surveillance, infrared photography surveillance, infrared interruption sensings.But, the high chi in road, magic high a zhang, the fight between invasion and the defence does not stop.For this reason, must the multiple novel Defense Technology Journal of development.
Optical fiber is cheap, be easy to install, disguise better, is not subjected to electromagnetic interference (EMI), also extremely payes attention in circumferential protective.Formerly one of technology is based on multimode optical fiber speckle sensor [T.S.Francis, Appl.Opt.32,4685-4689 (1993); A.Malki, Appl.Opt.35,5198-5201 (1996) etc.].This method has had product to come out, and obtains to use in many occasions.Its principle be light wave in multimode optical fiber because the interference between the different transmission mode forms speckle, and speckle image is changed by external disturbance and writes down speckle with CCD, perhaps with light hurdle intercepting local light power, the disturbance that is subjected on just can the perception multimode optical fiber.This method requires to use extraordinary multimode optical fiber, and cost is than higher.Formerly two of technology, be based on the mechanism of single-mode fiber microbending loss, whether from the variation of fiber transmission attenuation, judging has external interference to take place.Compare with using multimode optical fiber, the price of single-mode fiber is lower.But the method remolding sensitivity with microbending loss perception external disturbance is lower.Be easy to generate wrong report.Above-mentioned two kinds of methods can not determine all which position invasion occurs in.Formerly three of technology, be to use optical time domain reflectometer to measure the method for disturbance, the echo of generation is with the variation of external disturbance when measuring light wave and transmit in optical fiber.This method can determine that with respect to the time delay of x time optical fiber is subjected to the position of disturbance according to the moment that receives echo.But, adopt this method signal very faint, Measuring Time is longer, responds very slowly, is not suitable for dynamic detection.And the price of time-domain reflectomer is also very high.Formerly four of technology, U.S. Pat 2003/0198425 A1 is provided with two fibre circuits in the circumferential protective system, and two-way transmits rightabout light wave respectively.Measure disturbance and the back light signal takes place be transferred to mistiming of check point, determine the position of disturbance generation at both forward and reverse directions.In this patent, some kinds of optical fiber circuit structures have been designed.But it is the technology of non-location (non-locating) that optical fiber Sagnac ring is considered to.In the application of circumferential protective sensor, that invades the position determines it is an important function.
Summary of the invention
The objective of the invention is to overcome above-mentioned the deficiencies in the prior art, a kind of perimeter defence optical fiber sensor that is used for safety precaution is provided, it can not only find external disturbance, and can determine the position of external disturbance, and have that cost is low, system architecture simple, be convenient to expansion and easy advantage is installed.
Principle of the present invention is based on fiber loop mirror, and fiber loop mirror is an optical fiber Sagnac loop (being designated hereinafter simply as the Sagnac ring) as shown in Figure 1.This loop is to connect one relatively by two output ports of fiber coupler to encircle and constitute.Light divides clockwise and counterclockwise both direction transmission from a port a input of fiber coupler from port c, d output back ring, interfere when getting back to fiber coupler.The light wave of phase stem portion is got back to input port fully.This just this loop structure be called as the reason of fiber loop mirror.Can not interfere the part that disappears mutually to export in the light wave from the port b of coupling mechanism.When being disturbed in the optical fiber loop, the variation of coherence of light wave will be caused, this variation will be detected at port b.For dynamic variation, since relevant with the time that is transferred to coupling mechanism counterclockwise clockwise with the position that disturbance takes place, therefore can calculate the position that disturbance takes place according to the time domain specification of this variable signal.
Fig. 2 is the synoptic diagram of the principle of this time domain waveform of generation.C is the light velocity in the optical fiber among the figure.If the disturbance place is divided into L with the loop total length
1And L
2Two sections, L
1Be the distance of clockwise light wave (CW) from fiber coupler to the disturbance origination point, L
2Be the distance of counterclockwise light wave (CCW) from fiber coupler to the disturbance origination point.The disturbance that this two-beam ripple is stood when getting back to coupling mechanism has a mistiming.From this time response of interference signal, just can calculate the position of disturbance point.This is a very important information for circumferential protective.
The necessary condition that the Sagnac ring has the interference reflection characteristic is that light wave must be with single mode transport in optical fiber.The optical fiber that is to say fiber coupler and formation loop all is single-mode fiber.If multimode optical fiber, the interference between the pattern is just very complicated, and the light signal that its average effect can cause disturbance masks.Therefore, this Sagnac ring sensor be is used for, the single-mode fiber susceptibility of disturbance to external world must be utilized.
The principle of destabilization sensing of the present invention is when utilizing single-mode fiber generation deformation, the effect that the polarization state of light wave and phase place change.Usually the power that produces of outside invading, will cause optical fiber bending, reverse, deformation such as vibration.The local bending of single-mode fiber must make the fiber segment at this place stretch, as shown in Figure 3.Optical fiber span length is L if bend, and crooked radius-of-curvature is R, according to geometric relationship, and approximate can being expressed as of elongation of crooked back optical fiber: Δ L ≈ L
3/ 24R
2Light wave has increased transmission range, and the phase place of light wave is changed: Δ φ=2 π n Δ L/ λ.N is the refractive index of optical fiber in the formula, and λ is an optical wavelength.As seen, disturbance phase shift reducing and increase with the radius-of-curvature of bending.
Simultaneously, during fibre-optical bending, inside of optical fibre will produce uneven Strain Distribution.Thereby cause that optical fiber is creating a difference perpendicular to the effective refractive index on the both direction of optical fiber axial plane, and birefringence effect has just taken place.This effect causes the variation of the polarization state of light wave.According to the analysis of stress and photoelastic effect, the size of this birefringence effect is:
δn＝(n
3r
2/4R
2)(p
11-p
12)(1+v)
In the formula: r is a fiber radius, and p is an elasto-optical coefficient, and v is a Poisson ratio.As seen, the birefringence that causes of fibre-optical bending also is reducing and increase with radius-of-curvature.
In fact fiber-optic vibration is exactly a kind of bending of periodic swinging, so its fundamental characteristics can obtain from the phase shift variations and the birefringence variation of above-mentioned static analysis.The direct result of optic fibre turning is the rotation of light wave plane of polarization.Therefore similar to the performance of above-mentioned birefringence effect.It is smaller generally to reverse odds under faint disturbance.Can draw from above-mentioned analysis, the phase shift variations and the birefringence that utilize optical means monitoring disturbance to cause change, just can the disturbed moving situation of perception optical fiber, thus constitute a kind of circumferential protective sensor spare.
Technical solution of the present invention is as follows:
A kind of perimeter defence optical fiber sensor; be characterized in constituting by light source, sensor fibre, fiber coupler, first detector, second detector, signal processor and fiber optical circulator; described light source is single longitudinal mode or the less semiconductor laser of longitudinal mode number; the splitting ratio of described fiber coupler is 1: 1; the two ends of described sensor fibre respectively with two of described fiber coupler in the same way port be connected; constitute a Sagnac ring; be used for around buildings that requires to defend or zone, the position of above-mentioned each element relation is as follows:
First port of the described fiber optical circulator of output termination of described light source, second port of the described fiber coupler of second port of this fiber optical circulator, first port of this fiber coupler connects described signal processor through first detector, and the 3rd port of described fiber optical circulator connects described signal processor through second detector.
The single-mode fiber that described sensor fibre is sold for the merchant.
Described sensor fibre is the two optical fiber cables of single mode, two optical fiber of two optical fiber cable one ends of this single mode link to each other with the two-port of described fiber coupler, two identical single-mode fibers of the usefulness of the other end of optical cable are connected to a polarization rotator, constitute the Sagnac ring of a mid point generation polarization rotation.
Perimeter defence optical fiber sensor of the present invention has following characteristics and advantage:
1, the present invention adopts the Sagnac loop that single-mode fiber constitutes, and has the function that can find external disturbance and determine its position.
2, because the single-mode fiber industry size is huge, price is lower than multimode optical fiber, and the components and parts comparative maturity of various single-mode fibers, and price also is lower than the less multimode optical fiber element of consumption, therefore with compare based on multimode optical fiber speckle sensor, have the low outstanding advantage of cost.
3, compare with sensor, method, have the advantage that optical signal power is big, highly sensitive, response speed is fast, cheap based on time-domain reflectomer.
4, system architecture is simple, is convenient to expansion; Install simple and easy.
Description of drawings
Fig. 1 is optical fiber Sagnac ring synoptic diagram
Fig. 2 utilizes the Sagnac ring to realize the principle schematic that the disturbance location is detected
The synoptic diagram that Fig. 3 optical fiber bends when being subjected to outer force-disturbance
Fig. 4 is one of perimeter defence optical fiber sensor embodiment of the present invention structural representation
Fig. 5 is two structural representations of perimeter defence optical fiber sensor embodiment of the present invention
The two optical fiber Sagnac rings of Fig. 6 are realized the principle schematic that the disturbance location is detected
Embodiment
The invention will be further described below in conjunction with drawings and Examples, but should not limit protection scope of the present invention with this.
See also Fig. 4 earlier, Fig. 4 is one of perimeter defence optical fiber sensor embodiment of the present invention structural representation.As seen from the figure; perimeter defence optical fiber sensor of the present invention; constitute by light source 3, sensor fibre 2, fiber coupler 4, first detector 51, second detector 52, signal processor 6 and fiber optical circulator 7; described light source 3 is single longitudinal mode or the less semiconductor laser of longitudinal mode number; the splitting ratio of described fiber coupler 4 is 1: 1; the two ends of described sensor fibre 2 respectively with two of described fiber coupler 4 in the same way port be connected; constitute a Sagnac ring; be used for around buildings that requires to defend or zone 1, the position relation of above-mentioned each element is as follows:
The first port a of the described fiber optical circulator 7 of output termination of described light source 3, the second port b of this fiber optical circulator 7 meets the second port b of described fiber coupler 4, the first port a of this fiber coupler 4 connects described signal processor 6 through first detector 51, and the 3rd port c of described fiber optical circulator 7 connects described signal processor 6 through second detector 52.
The single-mode fiber that described sensor fibre 2 is sold for the merchant.
Fig. 5 is two structural representations of perimeter defence optical fiber sensor embodiment of the present invention, and 21 is sensor fibre among the figure, adopts the two optical fiber cables of commercial single mode in the present embodiment.Two optical fiber of optical cable one end link to each other with the two-port of fiber coupler 4.Two identical single-mode fibers of the usefulness of the other end of optical cable are connected to a polarization rotator 9, constitute the Sagnac ring of a mid point generation polarization rotation.Polarization rotator can utilize commercial half-wave plate, and it makes the light wave of the transmission of both direction produce opposite rotation.Under this layout, disturbance point has the geometric distributions of symmetry for this dual fiber ring.Owing to adopted polarization rotator, clockwise and counterclockwise twice disturbance standing of light wave have different polarization properties, so when getting back to the fiber coupler place and interfere, will obtain the time-domain signal relevant with the position.This just provides information for the location of disturbance.Its principle schematic is seen Fig. 6.The far-end of the two optical fiber cables of dot-and-dash line representative is a mid point for the ring that connects among the figure.Each section of two optical fiber is disturbed certain halfway, and its length is divided into L
1And L
2For clockwise with counterclockwise light wave the first half distance is the same, and half distance of back is transmitted on an other optical fiber, and midpoint is through polarization rotator 9, and different variations has taken place polarization state.Therefore variation has also taken place in the result of interference of two light waves when getting back to fiber coupler.
In this optical fiber loop structure, the light wave of light source 3 emissions is through the port b of fiber optical circulator to fiber coupler 4, through coupling ratio is that 1: 1 coupling mechanism is divided into the two-beam that amplitude equates, enter respectively in two optical fiber of sensor fibre, and return from another optical fiber through polarization rotator 9 backs.Therefore the light wave that in sensor fibre, has the both direction transmission.Under stable situation, return the light wave of fiber coupler 4, because interference effect, a part is returned output from the second port b of fiber coupler 4; Received by second detector 52 through circulator 7 backs.A part will be received by first detector 51 from the first port a output of coupling mechanism 4 because polarization rotation effect can not interfere mutually to disappear in addition.The photosignal computational analysis in signal processor 6 that receives, and obtain the change information of time domain, invasion and position thereof are judged.
According to thought of the present invention, transmitting illuminant adopts the laser diode of common communications wave band 1550nm, single-mode tail fiber output, and direct drive, output power are 1mW; Adopt the merchant to sell 1: 1 fiber coupler and make up the Sagnac ring.The output light signal receives with the InGaAs-PIN detector, and amplifies with conventional amplifying circuit.Output signal data collecting card collection is recorded in the PC.When applying external force in Sagnac ring somewhere and making its crooked deformation, detector can detect the variation of signal intensity significantly.Two of technical scheme shown in Figure 5 though the fiber lengths that needs has increased by one times, does not need when laying to get back to the detecting instrument place, is convenient to use in the occasion that this requirement is arranged.
Claims (3)
1; a kind of perimeter defence optical fiber sensor; it is characterized in that by light source (3); sensor fibre (2); fiber coupler (4); first detector (51); second detector (52); signal processor (6); and fiber optical circulator (7) constitutes; described light source (3) is single longitudinal mode or the less semiconductor laser of longitudinal mode number; the splitting ratio of described fiber coupler (4) is 1: 1; the two ends of described sensor fibre (2) respectively with two of described fiber coupler (4) in the same way port be connected; constitute a Sagnac ring; be used for around the buildings that requires to defend or zone (1), the position of above-mentioned each element relation is as follows:
First port (a) of the described fiber optical circulator of output termination (7) of described light source (3), second port (b) of this fiber optical circulator (7) connects second port (b) of described fiber coupler (4), first port (a) of this fiber coupler (4) connects described signal processor (6) through first detector (51), and the 3rd port (c) of described fiber optical circulator (7) connects described signal processor (6) through second detector (52).
2, perimeter defence optical fiber sensor according to claim 1 is characterized in that the single-mode fiber that described sensor fibre (2) is sold for the merchant.
3, perimeter defence optical fiber sensor according to claim 1, it is characterized in that described sensor fibre (2) is the two optical fiber cables of single mode, two optical fiber of two optical fiber cable one ends of this single mode link to each other with the two-port of described fiber coupler (4), two identical single-mode fibers of the usefulness of the other end of optical cable are connected to a polarization rotator (9), constitute the Sagnac ring of a mid point generation polarization rotation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200710038259 CN101025845A (en) | 2007-03-21 | 2007-03-21 | Perimeter defense optical fiber sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200710038259 CN101025845A (en) | 2007-03-21 | 2007-03-21 | Perimeter defense optical fiber sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101025845A true CN101025845A (en) | 2007-08-29 |
Family
ID=38744109
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200710038259 Pending CN101025845A (en) | 2007-03-21 | 2007-03-21 | Perimeter defense optical fiber sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101025845A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101556724B (en) * | 2008-04-09 | 2011-06-01 | 中国科学院半导体研究所 | Safety management system of optical fiber perimeter and pattern recognition method thereof |
| CN103150859A (en) * | 2013-02-01 | 2013-06-12 | 北京佳讯飞鸿电气股份有限公司 | Foreign matter limit invasion monitoring system based on fiber Bragg gratings |
| CN104751585A (en) * | 2015-03-24 | 2015-07-01 | 中国电子科技集团公司第八研究所 | Fiber fence unit |
| CN111044771B (en) * | 2019-12-31 | 2021-01-05 | 华中科技大学 | Non-closed optical fiber loop current sensing device and current measuring method |
| CN115035667A (en) * | 2022-05-13 | 2022-09-09 | 南京邮电大学 | Photon fence system for optical fiber mode division multiplexing real-time video transmission |
-
2007
- 2007-03-21 CN CN 200710038259 patent/CN101025845A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101556724B (en) * | 2008-04-09 | 2011-06-01 | 中国科学院半导体研究所 | Safety management system of optical fiber perimeter and pattern recognition method thereof |
| CN103150859A (en) * | 2013-02-01 | 2013-06-12 | 北京佳讯飞鸿电气股份有限公司 | Foreign matter limit invasion monitoring system based on fiber Bragg gratings |
| CN104751585A (en) * | 2015-03-24 | 2015-07-01 | 中国电子科技集团公司第八研究所 | Fiber fence unit |
| CN111044771B (en) * | 2019-12-31 | 2021-01-05 | 华中科技大学 | Non-closed optical fiber loop current sensing device and current measuring method |
| CN115035667A (en) * | 2022-05-13 | 2022-09-09 | 南京邮电大学 | Photon fence system for optical fiber mode division multiplexing real-time video transmission |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AU760272B2 (en) | Intrinsic securing of fibre optic communication links | |
| CN100561144C (en) | Distributed optical fiber vibration sensing method and device | |
| US7514670B2 (en) | Distributed fiber optic sensor with location capability | |
| CN101871809B (en) | Defense area optical fiber distribution type vibration sensor and perimeter alarm system adopting same | |
| US5419636A (en) | Microbend fiber-optic temperature sensor | |
| AU1536900A (en) | Apparatus and method for monitoring a structure using a counter-propagating signal method for locating events | |
| CN103630229B (en) | A kind of differential coherence time domain scatter-type distributed optical fiber vibration sensing method and system | |
| CN110440900A (en) | A kind of optical fiber distributed type acoustic wave sensing system | |
| CN101025845A (en) | Perimeter defense optical fiber sensor | |
| CN110441919A (en) | Sagnac full polarization fibre interferometer system for the evaluation and test of optical fibre gyro noise | |
| CN101021961A (en) | Single-mode optical fiber perimeter defense sensor | |
| Yuan et al. | Loop topology based white light interferometric fiber optic sensor network for application of perimeter security | |
| CN104180831A (en) | Sensitivity-enhanced optical time domain reflection distributed Michelson interferometer based on two-core optical fiber | |
| CN101894438A (en) | Positioning optical fiber vibration intrusion-detection system capable of measuring pressure | |
| CN201032465Y (en) | Perimeter defense optical fiber sensor | |
| CN102313141A (en) | Optical fiber vibration sensing system for pipeline leakage detection | |
| CA2371576A1 (en) | Intrinsic securing of fibre optic communication links | |
| CN201043924Y (en) | Single-mode optical fiber perimeter defense sensor | |
| CN102646308A (en) | Perimeter security system based on single optical fiber and fiber bragg grating of single optical fiber | |
| CN108254101A (en) | A kind of polarization interference formula passive fiber temperature sensor | |
| CN102622840A (en) | Peripheral security protection system based on single-optical-fiber cable | |
| CN208968667U (en) | A kind of quasi-distributed acoustic detection sensor | |
| CN204537361U (en) | A kind of fiber fence unit | |
| CN201540180U (en) | Novel pressure sensing system | |
| CN201983851U (en) | Bireflection delayed type locatable all-fiber vibration sensor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |