CN105021216A - Optical fiber perimeter sensing device realizing polarization-induced fading resistance - Google Patents
Optical fiber perimeter sensing device realizing polarization-induced fading resistance Download PDFInfo
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- CN105021216A CN105021216A CN201410177760.XA CN201410177760A CN105021216A CN 105021216 A CN105021216 A CN 105021216A CN 201410177760 A CN201410177760 A CN 201410177760A CN 105021216 A CN105021216 A CN 105021216A
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Abstract
The invention provides an optical fiber perimeter sensing device realizing polarization-induced fading resistance. An Er-doped narrow linewidth fiber laser serves as a light source, and optical signals emitted by the light source are random polarization state signals. The polarization state of the optical signals emitted by the light source changes rapidly, thereby being equivalent to that light breaks up into a plurality of randomly-polarized tiny light components when the optical signals emitted by the light source are transmitted on two interference arms. The overall interference result received by detectors is the statistical average of interferences of the randomly-polarized tiny light components passing the two interference arms. Because the changing speed of the polarization state of polarized light output by the Er-doped narrow linewidth fiber laser is very high and is far higher than the detection speed of the detectors, the interference result tends to be stable and is half of the peak polarization state, and thus the problem of polarization-induced fading caused by various polarization disturbances in a system can be solved.
Description
Technical field
The invention belongs to sensing and detection technique field, particularly relate to a kind of optical fiber perimeter sensing device realizing anti-polarization decay.
Background technology
Along with the development of optical fiber sensing technology, Fibre Optical Sensor is successfully applied to the safety precaution fields such as perimeter intrusion detecting, distribution type fiber-optic circumference sensor-based system is mainly used in perimeter protection, earthquake detection etc., optical fiber used reaches dozens of kilometres kilometer even up to a hundred, if will be very expensive with polarization maintaining optical fibre and corresponding supporting original paper thereof, therefore based on the consideration of cost, Mach-Zehnder (Mach-Zehnder) interferometer generally adopts general single mode fiber.Due to single-mode fiber transmission is two orthogonal linearly polarized modes, and in fact corresponding with this two linearly polarized modes in single-mode fiber refractive index n
xand n
yand unequal, will birefringent phenomenon be produced like this.When optical fiber occur micro-curved, distortion or environment temperature etc. change time, the refractive index n that two linearly polarized modes of Optical Fiber Transmission are corresponding
xand n
yalso change thereupon, thus Mach-Zehnder interferometer signal arm or reference arm output polarisation of light state are changed, such two-beam is just also non-fully interference when interfering, thus causes the visibility of interfering rear signal to reduce; After interfering, the phase place of signal also can be subject to the impact of polarization state, light source and environment and cause phase of output signal change thus cause position calculation error simultaneously.When the polarization state of two interference lights is mutually orthogonal under extreme case, can cause the failure of interferometry, this can cause very large impact to the performance of system.In addition owing to interfering the visibility of rear signal to change, cause the amplitude that outputs signal unstable, provide the signal of amplitude stability therefore can not to follow-up judgement, have impact on identification and the judgement of signal, make the rate of failing to report of system and rate of false alarm higher.
Up to now, the technology that the polarization decay of existing various Fibre Optical Sensor suppresses is suggested, studies and apply.These solutions can be summarized as five classes.One is adopt polarization separation detection technique.This technology can use general single-mode fiber interference structure, by detecting respectively and comparing the luminous power on pairwise orthogonal polarization direction, realizes anti-polarization decay, and the subject matter of the program is that detection technique is complicated.Second method adopts to disturb inclined technology.Disturbing inclined technology is by distinct methods in fiber interference structure, carries out active, quick, periodic disturbance, realize the depolarization of two interference lights on time average, to realize the object of anti-polarization decay to polarisation of light state.The major issue of this method is that to disturb inclined cost compare high.The third method is that depolarization, to eliminate polarization phase noise, assigns depolarizer to solve polarization decay problem in fiber interference structure before light enters interference mechanism.But depolarization is general only effective to broad spectrum light source.4th kind of method is input polarization feedback control method.Program feedback control procedure is more complicated, and system operation maintenance cost is also higher.Lung biopsy is faraday rotation mirror method.By increasing reflecting element at sensor fibre end, light reflection end uses faraday rotation mirror effectively can improve the polarization stability of system, and the subject matter of the program is that system is more complicated.
Summary of the invention
The object of the invention is to solve existing distribution type fiber-optic circumference sensor-based system to degenerate because using single-mode fiber to there is polarization, thus the problem of quality of output signals and positioning precision is interfered in impact, proposes a kind of optical fiber perimeter method for sensing realizing anti-polarization decay.The present invention is by using er-doped narrow cable and wide optical fiber laser light source, the random polarization light signal utilizing it to send, realize anti-polarization decay phenomenon, the amplitude solving output signal is unstable, stablize the visibility that light path exports, in resolution system, various polarization is degenerated the polarization phase noise and polarization decay problem brought thus, improves the positioning precision of interference signal quality and sensor-based system.
Technical scheme of the present invention: a kind of optical fiber perimeter sensing device realizing anti-polarization decay, device adopts bidirectional optical fiber Mach-Zehnder interferometer, described interferometer comprises laser instrument 1, coupling mechanism 2, coupling mechanism 3, coupling mechanism 4, photodetector 5 and photodetector 6, connected mode is laser instrument butt coupling device 1, it is counterclockwise through coupling mechanism 3 coupling mechanism 4 clockwise respectively that coupling mechanism 2 is divided into two-way light source, coupling mechanism 3 connects photodetector 5, and coupling mechanism 4 connects photodetector 6; Described light source is narrow cable and wide optical fiber laser.
Described laser instrument sends the signal of random polarization state.
The present invention's beneficial effect is compared with prior art:
(1) result of interference of the present invention is the statistical average that the small light component of infinite multiple random polarization interferes, and therefore its intetference-fit strengthening is the half of peak value polarization, and result of interference is highly stable.In this system, components and parts are few, and system reliability is high.
(2) whole system is without the need to Polarization Control device and polarization maintaining optical fibre, and cost is low.
Accompanying drawing explanation
Fig. 1 is the location structure schematic diagram adopting bidirectional Mach-Zehnder interferometer
In figure: 1 is laser instrument, 2,3,4 is coupling mechanism, and 5,6 is photodetector.
Embodiment
Preferred embodiment of the present invention accompanying drawings is as follows:
Be illustrated in figure 1 the system location structure schematic diagram of employing bidirectional Mach-Zehnder interferometer scheme, figure comprises fiber laser 1, coupling mechanism 2, coupling mechanism 3, coupling mechanism 4, detector 5 and detector 6.The light sent when fiber laser is divided into two-way one road light to coupling mechanism 3 through coupling mechanism 2, after the two-arm of interferometer, interfere when arriving coupling mechanism 4, form a clockwise Mach-Zehnder interferometer, the signal after interference is accepted by detector 5 after guiding optical fiber; Through another Lu Guangzhi coupling mechanism 4 that coupling mechanism 2 separates, after the two-arm of interferometer, arrive coupling mechanism 3 and interfere, the Mach-Zehnder interferometer that also formation one is counterclockwise, the signal after interference is received by detector 4 after guiding optical fiber.When the external world has disturbing signal A to act on the two-arm of Mach-Zehnder interferometer, make fiber optic interferometric arm produce mechanical vibration, mechanical vibration change the optical path difference of Mach-Zehnder interferometer two-arm, thus change the phase place of interference signal.Like this by detecting the phase place change of interference signal, just vibration event can be detected.
Light source of the present invention is er-doped narrow cable and wide optical fiber laser, and the light signal that fiber laser sends is random polarization state signal, is divided into two-way through coupling mechanism 2, and this two-way light is formed clockwise and counterclockwise two interferometers respectively through coupling mechanism 3 and 4 again.In any one Mach-Zehnder interferometer, interfere the light component intensity of arm identical for two, polarization state is random.Two polarization states of interfering the light signal of arm are stochastic distribution, and the result of interference of detector is also random, and extreme case is when both polarization directions are consistent, and interfere the strongest, when polarization state is orthogonal, interference is zero.The light signal sent due to fiber laser is random polarization, so can be equivalent to light signal that light source sends two interfere arms transmit time, light is decomposed into the small light component of infinite multiple random polarization, the statistical average that the small light component that total result of interference that detector receives is through infinite multiple random polarization of two interference arms interferes.Because the speed of fiber laser polarization state change is far away higher than the response speed of detector, so its statistics result of interference is highly stable.So just can the polarization decay problem brought of various polarization scrambling in resolution system.
Claims (2)
1. one kind realizes the optical fiber perimeter sensing device of anti-polarization decay, device adopts bidirectional optical fiber Mach-Zehnder interferometer, described interferometer comprises laser instrument 1, coupling mechanism 2, coupling mechanism 3, coupling mechanism 4, photodetector 5 and photodetector 6, connected mode is laser instrument butt coupling device 1, it is counterclockwise through coupling mechanism 3 coupling mechanism 4 clockwise respectively that coupling mechanism 2 is divided into two-way light source, coupling mechanism 3 connects photodetector 5, and coupling mechanism 4 connects photodetector 6; It is characterized in that described light source is narrow cable and wide optical fiber laser.
2. a kind of optical fiber perimeter sensing device realizing anti-polarization decay according to claim 1, it is characterized in that, laser instrument used sends the signal of random polarization state.
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| CN201410177760.XA CN105021216A (en) | 2014-04-28 | 2014-04-28 | Optical fiber perimeter sensing device realizing polarization-induced fading resistance |
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Cited By (6)
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|---|---|---|---|---|
| CN105737867A (en) * | 2016-03-31 | 2016-07-06 | 深圳市太阳讯传感科技有限公司 | SNR (signal to noise ratio) control device and method for optical fiber perimeter safety protection system |
| CN106052842A (en) * | 2016-08-05 | 2016-10-26 | 上海交通大学 | Distributed fiber vibration sensing system capable of eliminating declining noises and demodulation method of system |
| CN107576341A (en) * | 2017-08-09 | 2018-01-12 | 武汉隽龙科技股份有限公司 | The apparatus and method that polarization decay is eliminated in OFDR |
| CN107677358A (en) * | 2017-09-08 | 2018-02-09 | 国网安徽省电力公司安庆供电公司 | Broken localization method outside a kind of determination circuit |
| CN109323712A (en) * | 2018-12-04 | 2019-02-12 | 桂林聚联科技有限公司 | A kind of random polarization light source |
| CN114018391A (en) * | 2021-11-04 | 2022-02-08 | 全球能源互联网研究院有限公司 | Method and device for inhibiting interference light intensity fading |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105737867A (en) * | 2016-03-31 | 2016-07-06 | 深圳市太阳讯传感科技有限公司 | SNR (signal to noise ratio) control device and method for optical fiber perimeter safety protection system |
| CN105737867B (en) * | 2016-03-31 | 2018-07-06 | 深圳市太阳讯传感科技有限公司 | A kind of optical fiber perimeter security protection system signal-to-noise ratio control device and method |
| CN106052842A (en) * | 2016-08-05 | 2016-10-26 | 上海交通大学 | Distributed fiber vibration sensing system capable of eliminating declining noises and demodulation method of system |
| CN107576341A (en) * | 2017-08-09 | 2018-01-12 | 武汉隽龙科技股份有限公司 | The apparatus and method that polarization decay is eliminated in OFDR |
| CN107576341B (en) * | 2017-08-09 | 2021-06-04 | 武汉昊衡科技有限公司 | Device and method for eliminating polarization fading in OFDR (offset frequency domain digital radiography) |
| CN107677358A (en) * | 2017-09-08 | 2018-02-09 | 国网安徽省电力公司安庆供电公司 | Broken localization method outside a kind of determination circuit |
| CN109323712A (en) * | 2018-12-04 | 2019-02-12 | 桂林聚联科技有限公司 | A kind of random polarization light source |
| CN114018391A (en) * | 2021-11-04 | 2022-02-08 | 全球能源互联网研究院有限公司 | Method and device for inhibiting interference light intensity fading |
| CN114018391B (en) * | 2021-11-04 | 2023-09-26 | 全球能源互联网研究院有限公司 | Method and device for inhibiting interference light intensity fading |
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Application publication date: 20151104 |