CN103528666A - Long-distance optical fiber vibration detection device and method on basis of Sagnac interference - Google Patents
Long-distance optical fiber vibration detection device and method on basis of Sagnac interference Download PDFInfo
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- CN103528666A CN103528666A CN201310470928.1A CN201310470928A CN103528666A CN 103528666 A CN103528666 A CN 103528666A CN 201310470928 A CN201310470928 A CN 201310470928A CN 103528666 A CN103528666 A CN 103528666A
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Abstract
The invention discloses a long-distance optical fiber vibration detection device on the basis of Sagnac interference, which comprises a light source, a photoelectric detector, an optical circulator, a 2*2 coupler and an optical-fiber delay fiber. A laser signal sent out by the light source enters the 2*2 coupler by the optical circulator; the optical signal is divided into two paths at the position of the 2*2 coupler; one path of optical signal A enters an optical fiber to be detected by the optical-fiber delay fiber and a Fresnel reflection optical signal returned from the tail end enters the 2*2 coupler; the other path of optical signal B directly enters the optical fiber to be detected and the Fresnel reflection optical signal returned from the tail end enters the optical-fiber delay fiber by the 2*2 coupler and passes through the optical-fiber delay fiber for one circle to return to the 2*2 coupler; and the optical signal is interfered at the position of the 2*2 coupler and an interference signal is sensed by the photoelectric detector through the optical circulator. Compared with a conventional single-ended interference optical path, a single-ended Sagnac interference optical-fiber optical path of the long-distance optical fiber vibration detection device has the advantage that insertion loss is reduced by about 5dB.
Description
Technical field
The present invention relates to technical field of measurement and test, particularly a kind of long-distance optical fiber vibration pick-up unit of interfering based on Sagnac, also relates to a kind of long-distance optical fiber vibration detection method of interfering based on Sagnac.
Background technology
Traditional single-end optical fiber Sagnac optical interference circuit is implemented to long distance and detects very much, and main cause has: (1) final signal of interfering that produces is that laser produces at the Fresnel reflection of optical fiber connector end face, and this makes interference light very faint; (2) in traditional single-end optical fiber Sagnac optical interference circuit, laser will be back and forth three times through 3 * 3 coupling mechanism, each attenuated optical signal 5dB, the attenuated optical signal being produced by coupling mechanism has just reached 15dB, causes interference signal intensity again to produce large decay.
As shown in Figure 1, in traditional single-end optical fiber Sagnac optical interference circuit, coupling mechanism 11 by 3 * 3 and fiber delay time fine 9 forms optical interference circuit, when having generation of vibration, the phase place of light changes, by interfering the variation that this variation is converted to light intensity, so just can detection fiber whether vibrate as long as detect light intensity.
The continuous light that light source 7 produces enters 3 * 3 coupling mechanism 11 from the second port 2, light is divided into 2 tunnels, and the first via, through the 4th port the 4-the first port one-the five-port 5, enters testing fiber 10, at optical fiber connector generation Fresnel reflection, reflected light enters 3 * 3 coupling mechanism 11 through five-port 5; The second tunnel directly enters testing fiber 10 through five-port 5, and at optical fiber connector generation Fresnel reflection, reflected light enters 3 * 3 coupling mechanisms 11 through five-port 5, through the first port one-four port 4, again enters 3 * 3 coupling mechanisms 11; The light loss of the 6th port 6 consumes.This two-way light is divided in light intensity 1:1 ratio by same light beam, and optical path difference is 0, at 3 * 3 coupling mechanism 11 places, interferes, and interference light enters photodetector 8 through the 3rd port 3.
When having optical fiber that vibration occurs, cause that the phase place of light changes, and the path difference that two-way light is advanced due to light, its time difference that produces phase place variation has any different, and while therefore interfering at 3 * 3 coupling mechanism 11 places, it is different that the phase place of two-way light changes.Phase place variation at 3 * 3 coupling mechanism 11 place's light converts light intensity variation to, converts the Strength Changes of electric signal at photodetector 8 places to.
The main optical device of single-end optical fiber Sagnac optical interference circuit is 3 * 3 coupling mechanisms 11, and light can produce the decay of 5dB through 3 * 3 coupling mechanisms, by optical path analysis above, known: the continuous light signal that laser instrument sends will be back and forth three times through 3 * 3 coupling mechanisms, the attenuated optical signal being produced by coupling mechanism so has just reached 15dB.The light signal interfering is that light signal produces through the end face Fresnel reflection of optical fiber connector, and the intensity of Fresnel reflection only has 4% of former intensity of reflected light, and interference signal light intensity is very weak.Therefore the fiber-optic vibration pick-up unit of interfering based on Sagnac of optical fiber is difficult to reach long distance detection, has greatly limited the practicalization of this light path.
Summary of the invention
The present invention proposes a kind of long-distance optical fiber vibration pick-up unit and method of interfering based on Sagnac, has solved the large problem of interference light loss in the long distance detection of existing single-end optical fiber Sagnac optical interference circuit.
Technical scheme of the present invention is achieved in that
The long-distance optical fiber vibration pick-up unit that Sagnac interferes, comprises that light source, photodetector, optical circulator, 2 * 2 coupling mechanisms and fiber delay time are fine;
The laser signal that described light source sends is through optical circulator, enter 2 * 2 coupling mechanisms, at 2 * 2 coupling mechanism place light signals, be divided into two-way: a road light signal A, enters testing fiber through fiber delay time fibre, the Fresnel reflection light signal that end returns, enters 2 * 2 coupling mechanisms; Another road light signal B, directly enters testing fiber, and the Fresnel reflection light signal that end returns, through 2 * 2 coupling mechanisms, enters fiber delay time fibre, through the fine circle of fiber delay time, gets back to 2 * 2 coupling mechanisms;
Light signal interferes at 2 * 2 coupling mechanism places, and interference signal process optical circulator is by photodetector sensing.
The invention allows for a kind of long-distance optical fiber vibration detection method of interfering based on Sagnac, comprise the following steps: the laser signal that light source sends is through optical circulator, enter 2 * 2 coupling mechanisms, at 2 * 2 coupling mechanism place light signals, be divided into two-way: a road light signal A, through fiber delay time fibre, enter testing fiber, the Fresnel reflection light signal that end returns, enters 2 * 2 coupling mechanisms; Another road light signal B, directly enters testing fiber, and the Fresnel reflection light signal that end returns, through 2 * 2 coupling mechanisms, enters fiber delay time fibre, through the fine circle of fiber delay time, gets back to 2 * 2 coupling mechanisms; Light signal interferes at 2 * 2 coupling mechanism places, and interference signal process optical circulator is by photodetector sensing.
The invention has the beneficial effects as follows:
(1) optic fibre light path that single-ended Sagnac interferes is compared with traditional single-ended optical interference circuit, and Insertion Loss has reduced about 5dB;
(2), under identical condition, only the improvement by light path just can, so that the detection range of the equipment of interfering based on single-end optical fiber Sagnac when surveying vibration signal grown 3 times, promote the application of this equipment in length detects apart from vibration signal greatly.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skills, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is the structural representation of traditional single-end optical fiber Sagnac optical interference circuit;
Fig. 2 is the structural representation of long-distance optical fiber vibration pick-up unit of interfering based on Sagnac of the present invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.
In realization, meet under the prerequisite of single-end optical fiber Sagnac interference, the very weak reason of existing light path interference signal mainly comes from the Insertion Loss of 3 * 3 coupling mechanisms, due to optical interference circuit need continuous light signal that laser instrument sends back and forth three times through 3 * 3 coupling mechanisms, produce 15dB decay, this is a very large Insertion Loss to original just very weak interference light signal, has also greatly limited the application of the fiber-optic vibration pick-up unit that in long distance detection, Sagnac interferes.
The present invention solves the large problem of interference light loss long distance detection from light path aspect, single-end optical fiber Sagnac optical interference circuit discards tradition, by the introducing of low-loss device ring of light device, meeting under the prerequisite of single-ended detection, the single-end optical fiber optical interference circuit pair of realizing based on Sagnac detects with the long distance of vibration signal.
As shown in Figure 2, long-distance optical fiber vibration pick-up unit of interfering based on Sagnac of the present invention, comprises light source 7, photodetector 8, optical circulator 26,2 * 2 coupling mechanisms 25 and fiber delay time fibre 9.
The laser signal that light source 7 sends is through optical circulator 26, enter 2 * 2 coupling mechanisms 25, light signal is divided into two-way herein: a road light signal A, through fiber delay time fibre 9, enter testing fiber 10, in Fig. 2, the transmission path of light signal A is port 21 → 23 → 22 → 24, the Fresnel reflection light signal that end returns, enters 2 * 2 coupling mechanisms 25; Another road light signal B, directly enter testing fiber, in Fig. 2, the transmission path of light signal B is port 21 → 24, the Fresnel reflection light signal that end returns, through 2 * 2 coupling mechanisms 25, enter fiber delay time fibre 9, through fine 9 one circles of fiber delay time, get back to 2 * 2 coupling mechanisms 25, in Fig. 2, the transmission path of light signal B is port 24 → 22 → 23.Identical at the two ways of optical signals light path at 2 * 2 coupling mechanism 25 places like this, phase place is identical, is strict coherent light.Therefore, light signal interferes at 2 * 2 coupling mechanism 25 places, and interference signal process optical circulator 26 is by photodetector 8 sensings.When having generation of vibration on testing fiber 10, the phase place of light signal A and light signal B changes respectively, but for two ways of optical signals, it is different that vibration signal passes to the light path of 2 * 2 coupling mechanisms 25.Very responsive for phase place owing to interfering, therefore can by interference signal, sense vibration at 2 * 2 coupling mechanism 25 places.
Single-end optical fiber Sagnac optical interference circuit of the present invention will be back and forth three times through 2 * 2 coupling mechanisms 25, each attenuated optical signal 3dB, the attenuated optical signal being produced by 2 * 2 coupling mechanisms like this has 9dB; Laser signal will arrive photodetector 8 through optical circulator 26 twice back and forth, each attenuated optical signal 0.6dB, and the attenuated optical signal being produced by optical circulator 26 like this has 1.2dB.Therefore, novel single-end optical fiber Sagnac optical interference circuit is because of photo-coupler in light path and optical circulator, and the light loss of generation is 10.2dB, than traditional Sagnac optical interference circuit Insertion Loss few 4.8dB.
The invention allows for a kind of long-distance optical fiber vibration detection method of interfering based on Sagnac, the method specifically comprises the following steps: the laser signal that light source sends is through optical circulator, enter 2 * 2 coupling mechanisms, at 2 * 2 coupling mechanism place light signals, be divided into two-way: a road light signal A, through fiber delay time fibre, enter testing fiber, the Fresnel reflection light signal that end returns, enters 2 * 2 coupling mechanisms; Another road light signal B, directly enters testing fiber, and the Fresnel reflection light signal that end returns, through 2 * 2 coupling mechanisms, enters fiber delay time fibre, through the fine circle of fiber delay time, gets back to 2 * 2 coupling mechanisms; Light signal interferes at 2 * 2 coupling mechanism places, and interference signal process optical circulator is by photodetector sensing.
Long-distance optical fiber vibration pick-up unit and the method for based on Sagnac, interfering that the present invention proposes, the optic fibre light path that single-ended Sagnac interferes is compared with traditional single-ended optical interference circuit, and Insertion Loss has reduced about 5dB.Under identical condition, only the improvement by light path just can, so that the detection range of the equipment of interfering based on single-end optical fiber Sagnac when surveying vibration signal grown 3 times, promote the application of this equipment in length detects apart from vibration signal greatly.
The foregoing is only preferred embodiment of the present invention, in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.
Claims (2)
1. a long-distance optical fiber vibration pick-up unit of interfering based on Sagnac, is characterized in that, comprises that light source, photodetector, optical circulator, 2 * 2 coupling mechanisms and fiber delay time are fine;
The laser signal that described light source sends is through optical circulator, enter 2 * 2 coupling mechanisms, at 2 * 2 coupling mechanism place light signals, be divided into two-way: a road light signal A, enters testing fiber through fiber delay time fibre, the Fresnel reflection light signal that end returns, enters 2 * 2 coupling mechanisms; Another road light signal B, directly enters testing fiber, and the Fresnel reflection light signal that end returns, through 2 * 2 coupling mechanisms, enters fiber delay time fibre, through the fine circle of fiber delay time, gets back to 2 * 2 coupling mechanisms;
Light signal interferes at 2 * 2 coupling mechanism places, and interference signal process optical circulator is by photodetector sensing.
2. a long-distance optical fiber vibration detection method of interfering based on Sagnac, is characterized in that, comprises the following steps:
The laser signal that light source sends, through optical circulator, enters 2 * 2 coupling mechanisms, at 2 * 2 coupling mechanism place light signals, is divided into two-way: a road light signal A, through fiber delay time fibre, enter testing fiber, and the Fresnel reflection light signal that end returns, enters 2 * 2 coupling mechanisms; Another road light signal B, directly enters testing fiber, and the Fresnel reflection light signal that end returns, through 2 * 2 coupling mechanisms, enters fiber delay time fibre, through the fine circle of fiber delay time, gets back to 2 * 2 coupling mechanisms; Light signal interferes at 2 * 2 coupling mechanism places, and interference signal process optical circulator is by photodetector sensing.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104792402A (en) * | 2015-04-16 | 2015-07-22 | 华中科技大学 | Acoustic wave sensing measurement device based on optical fiber sagnac interferometer |
| CN108593089A (en) * | 2018-05-02 | 2018-09-28 | 张岳 | A kind of vibration of optical sensor and inducing method based on birefringence resonance effect |
| CN110320442A (en) * | 2019-06-20 | 2019-10-11 | 永州电力勘测设计院有限公司 | Utilize the lightning stroke localization method of the single-ended OPGW transmission line of electricity from ring of optical fiber |
| CN113340402A (en) * | 2021-05-27 | 2021-09-03 | 无锡科晟光子科技有限公司 | Positioning type distributed optical fiber vibration detector based on double-light-source design |
-
2013
- 2013-09-29 CN CN201310470928.1A patent/CN103528666A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104792402A (en) * | 2015-04-16 | 2015-07-22 | 华中科技大学 | Acoustic wave sensing measurement device based on optical fiber sagnac interferometer |
| CN108593089A (en) * | 2018-05-02 | 2018-09-28 | 张岳 | A kind of vibration of optical sensor and inducing method based on birefringence resonance effect |
| CN108593089B (en) * | 2018-05-02 | 2020-08-04 | 张岳 | Optical vibration sensor based on birefringence resonance effect and sensing method |
| CN110320442A (en) * | 2019-06-20 | 2019-10-11 | 永州电力勘测设计院有限公司 | Utilize the lightning stroke localization method of the single-ended OPGW transmission line of electricity from ring of optical fiber |
| CN113340402A (en) * | 2021-05-27 | 2021-09-03 | 无锡科晟光子科技有限公司 | Positioning type distributed optical fiber vibration detector based on double-light-source design |
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Application publication date: 20140122 |