CN102853920A - High-sensitivity Mach-Zahnder interference system - Google Patents
High-sensitivity Mach-Zahnder interference system Download PDFInfo
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- CN102853920A CN102853920A CN2012103764291A CN201210376429A CN102853920A CN 102853920 A CN102853920 A CN 102853920A CN 2012103764291 A CN2012103764291 A CN 2012103764291A CN 201210376429 A CN201210376429 A CN 201210376429A CN 102853920 A CN102853920 A CN 102853920A
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Abstract
The invention discloses a high-sensitivity Mach-Zahnder interference system, which is characterized in that a broad-spectrum light source is connected with a first port of a circulator through an optical fiber, a second port of the circulator is connected with one end of an acousto-optic modulator through an optical fiber, a signal generator is connected with the acousto-optic modulator to supply a pulse signal, the other end of the acousto-optic modulator is connected with the input end of a first optical-fiber coupler through an optical fiber, two output optical fibers of the first optical-fiber coupler are connected with a sensing optical-fiber ring and a reference optical-fiber ring and additionally provided with a first polarization controller, a third port of the circulator is connected with a light spectrum analyzer, and the phase difference corresponding to the two optical-fiber rings is measured by outputting the light spectrum; and the sensing optical-fiber ring and the reference optical-fiber ring are respectively formed by joining the input ends and the output ends of a second coupler and a third coupler, and the length of the sensing optical-fiber ring is identical to that of the reference optical-fiber ring. Multiple times of optical oscillation inside the optical-fiber rings are utilized to accumulate the phase variation of the optical fibers, so that the measurement sensitivity is greatly improved. In addition, the wavelength division multiplexing can be realized.
Description
Technical field
The present invention relates to a kind of high sensitivity Mach Ceng Degan and relate to system.
Background technology
Mach-Zehnder interferometer is widely used in Fibre Optical Sensor, the optical fiber communication.
Mach-Zehnder interferometer two arm optical path differences commonly used have intensity and two kinds of demodulation methods of spectrum, the sensitivity of intensity demodulation is very high, but monochromaticity, frequency stability, power stability to light source have larger requirement, measurement result can be subjected to the impact of polarisation of light attitude simultaneously, needs to overcome the problem of stability in practical process.
The sensitivity of spectrum demodulation is not high, but demodulation mode is simple, and light source uses common wide spectrum light source to get final product, and is less demanding to the power stability of light source.The acquisition methods of interference spectrum mainly contains two kinds, and a kind of is directly to use the spectrometer measurement interference spectum; Another is the device that adds a meticulous length scanning of FP at the wide spectrum light source output terminal, and receiving end uses the power probe probe power to change, and changes by output waveform and obtains.It is convenient directly than the second that first method obtains interference spectum, but within the long period of spectrometer scanning wavelength, interference spectum can drift about, and this can reduce measuring accuracy.It is low that second method has a cost, and response is fast, but because the nonlinear characteristic of the long PZT in control FP chamber needs Application standard tool and FBG to carry out wavelength scaling.
After getting access to spectrum, can realize by the position at detected peaks peak separation or single peak the demodulation of optical path difference, but because interference spectum is the sinusoidal pattern function, so there is very large error in the peak value location.For single peak, although the level by peak wavelength and its correspondence time comes measurement of optical path difference that very high sensitivity is arranged, the inferior measurement of level easily produces error, so these two kinds of method precision are still not high.Professor Jiang Yi of Beijing Institute of Technology has proposed the demodulation method based on Fourier transform, and this method has advantages of that precision is high.But this method needs complicated signal processing.
Summary of the invention
Technical matters to be solved by this invention provides a kind of high sensitivity Mach Ceng Degan and relates to system, is used for Fibre Optical Sensor.
High sensitivity Mach Ceng Degan of the present invention relates to system and comprises wide spectrum light source, optical fiber circulator, acousto-optic modulator, signal generator, first, second, third fiber coupler, the first Polarization Controller, spectroanalysis instrument.
Described wide spectrum light source connects the first port of circulator by optical fiber, the second port of circulator connects acousto-optic modulator one end by optical fiber, signal generator connects acousto-optic modulator provides pulse signal, the other end of acousto-optic modulator connects the first fiber coupler input end by optical fiber, two output optical fibres of the first fiber coupler connect sensing fiber ring, reference optical fiber ring, and add the first Polarization Controller, the 3rd port of circulator connects spectroanalysis instrument, measures two corresponding phase differential of fiber optic loop by output spectrum; Described sensing fiber ring, reference optical fiber ring are respectively second, third coupling mechanism input/output terminal and connect to form, and described sensing fiber ring and reference optical fiber ring length equate.
The coupling ratio of described the first fiber coupler is 1:1; The splitting ratio of described second, third coupling mechanism is identical, is 1:99～1:9 respectively, and the equal corresponding high coupling ratio of insertion loss between the two-port in the described sensing fiber ring.
Described high sensitivity Mach Ceng Degan relates to system and also comprises the second Polarization Controller, the 3rd Polarization Controller, and described sensor fibre and reference optical fiber add second, third Polarization Controller respectively.
The pulse signal that described signal generator provides is that dutycycle, cycle are adjustable.
Described high sensitivity Mach Ceng Degan relates to first wave division multiplexer, the Second Wave division multiplexer that system comprises that also two bandwidth wavelength all equate, the common port of described first, second wavelength division multiplexer connects described the first fiber coupler, the 3rd fiber coupler by optical fiber respectively, the multiplexing end of described first, second wavelength division multiplexer is relative, adds respectively in twos described sensing fiber ring in the multiplexing end between the same channel.Because the different fiber ring is in different channels, independently carries out demodulation by wave bands different on output spectrum at last, realize the wavelength-division multiplex of sensing fiber ring.
Described Mach Ceng Degan relates to principle and is: wide spectrum optical is through being modulated into pulsed light on the AOM intensity, input the first fiber coupler after, can be along clockwise and counterclockwise both direction transmission.The light pulse of transmission can be owing to being coupled to two pulse trains of formation in the optical fiber ring cavity by second, third fiber coupler the time clockwise; Because two fiber optic loop equal in length, second, third fiber coupler coupling ratio is equal, and two pulse trains are overlapping in time, and upper corresponding pulse power of per two times equates.Light also can produce upper overlapping pulse train of two times equally, counterclockwise.These four pulse trains arrive spectrometer by AOM secondary intensity modulated through circulator at last.
Vibrate in sensing fiber ring from the clockwise pulsed light of the first fiber coupler output can one group of light pulse sequence of formation, and pulse power decays according to the loss of fiber optic loop individual pen; And directly the pulse power by the second fiber coupler is high more a lot of than first light pulse (being called for short 1 rank pulse) of pulse train, then the pulse that this power is higher is through the 3rd fiber coupler, one group of light pulse sequence of same formation, the m rank pulse of these two pulse trains is overlapping in time, and all is vibrations m time and form in the ring of correspondence; Latter two pulse train arrives the first fiber coupler input end simultaneously, AOM just is in next pulse and produces state, be the logical state of light, just allow two m rank pulses finally enter spectrometer by AOM, on spectrometer, will record so the spectrum of these two pulse interference gained.
Same pulse of propagating counterclockwise also can finally obtain the spectrum that two m rank pulse interference obtain.And since light path identical, the interference spectrum of gained with obtain clockwise consistent.The phase differential of these two m rank pulses is m times of 1 rank pulse phase difference.
Therefore, sensing fiber ring length l
1And the relation between the interference spectrum can be expressed as:
Here, l
1, l
2Be respectively the length of sensing fiber ring and reference optical fiber ring, l
1≈ l
2, n is the effective refractive index of fiber core, λ
1And λ
2Be respectively two adjacent peak wavelengths of interference spectum or valley wavelength.Just can demodulate the sensor fibre phase place by interference spectum by formula (1) changes.
Beneficial effect of the present invention is:
1, the present invention compares with traditional double light path Mach-Zehnder interferometer, utilizes light multiple oscillation in the fiber optic loop, and the accumulation fiber phase changes, and measurement sensitivity is improved greatly;
2, the present invention can by using wavelength division multiplex device, realize wavelength-division multiplex.
Description of drawings
Below in conjunction with the drawings and specific embodiments technical scheme of the present invention is further described in detail.
Fig. 1 is that high sensitivity Mach Ceng Degan of the present invention relates to system construction drawing;
Fig. 2 is the structural drawing of transducing part optical fiber ring cavity of the present invention;
Fig. 3 has provided the multiplexing schematic diagram of sensing fiber ring;
Embodiment
Fig. 1 has provided high sensitivity Mach Ceng Degan and has related to system construction drawing, and wide spectrum light source 1 output light is by the first port of optical fiber circulator 2, and the second port of optical fiber circulator 2 connects acousto-optic modulator 3, and the 3rd port of optical fiber circulator 2 connects spectrometer 4.Signal generator 5 connects acousto-optic modulator 3 and provides duty cycle adjustable pulse signal.The coupling ratio that acousto-optic modulator 3 other ends access the first fiber coupler 6, the first fiber couplers is 1:1.Two output terminals of the first fiber coupler 6 are connected by the welding mode with two optical fiber ring cavities.The optical fiber that connects at second, third fiber coupler adds 9, two optical fiber ring cavities of the first Polarization Controller respectively by second, third fiber coupler 7,8 input/output terminal weldings and add second, third Polarization Controller 10,11 and form.
Among Fig. 1, the requirement of the pulse signal that sends of signal source 5 is the time that pulse width is enclosed less than light transmission one in the fiber optic loop, and the cycle size is
Here l
1Be sensor fibre ring length, l
3Be the first fiber coupler output tail optical fiber and two fiber optic loop tail optical fiber total lengths and, l
4Be the fiber lengths of AOM to the first fiber coupler, c is the light velocity in the vacuum, and m is integer.
The first Polarization Controller 9 is used for eliminating because the interference of the both direction pulse that fiber birefringence causes among Fig. 1.Second, third Polarization Controller 10,11 is used for adjusting two corresponding m of ring rank pulse, makes the contrast of output interference spectum reach maximum.
Fig. 2 has provided transducing part fiber optic loop cavity configuration figure, the optical fiber ring cavity is 1:99 by two splitting ratios and forms to second, third fiber coupler 7,8 the 1:9, concrete method of attachment is identical, be A, B such as two input ends of fiber coupler among Fig. 2, two output terminals are C, D, AC and BD are straight-through arm, the insertion loss at the BD two ends in the access ring corresponding high coupling ratio, for example 0.1dB(99%), 0.5dB(90%).
Fig. 3 has provided the multiplexing schematic diagram of sensing fiber ring, first, second wavelength division multiplexer 12,13 is respectively the wavelength division multiplexer WDM that two bandwidth wavelength all equate, first, second wavelength division multiplexer 12,13 common port connect the first fiber coupler 6, the 3rd fiber coupler 8 by optical fiber respectively, first, second wavelength division multiplexer 12,13 multiplexing end are relative, in the multiplexing end, the same channel among adds the described fiber optic loop of Fig. 2 in twos.And the length of each sensing fiber ring of different channels equates with the reference optical fiber ring length, and the incoming fiber optic length 14 outside the sensing fiber ring also equates respectively, so just realizes the multiplexing of a plurality of fiber optic loop.For the light of clockwise propagation, different wave length enters different channels by 12, converges in the optical fiber by 13 again at last through different reference optical fiber rings.For the light of counterclockwise propagation, different wave length enters different channels by 13, converges in the optical fiber by 12 again at last through different reference optical fiber rings.Wavelength corresponding to the different channels of observing in the spectrometer is with regard to the phase information of corresponding different sensing fiber rings.
It should be noted last that, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although with reference to preferred embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement technical scheme of the present invention, and not breaking away from the spirit and scope of technical solution of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.
Claims (5)
1. a high sensitivity Mach Ceng Degan relates to system, it is characterized in that, comprises wide spectrum light source, optical fiber circulator, acousto-optic modulator, signal generator, first, second, third fiber coupler, the first Polarization Controller, spectroanalysis instrument;
Described wide spectrum light source connects the first port of circulator by optical fiber, the second port of circulator connects acousto-optic modulator one end by optical fiber, signal generator connects acousto-optic modulator provides pulse signal, the other end of acousto-optic modulator connects the first fiber coupler input end by optical fiber, two output optical fibres of the first fiber coupler connect sensing fiber ring, reference optical fiber ring, and add the first Polarization Controller, the 3rd port of circulator connects spectroanalysis instrument, measures two corresponding phase differential of fiber optic loop by output spectrum; Described sensing fiber ring, reference optical fiber ring are respectively second, third coupling mechanism input/output terminal and connect to form, and described sensing fiber ring and reference optical fiber ring length equate.
2. high sensitivity Mach Ceng Degan according to claim 1 relates to system, it is characterized in that, the coupling ratio of described the first fiber coupler is 1:1; The splitting ratio of described second, third coupling mechanism is identical, is 1:99～1:9 respectively, and the equal corresponding high coupling ratio of insertion loss between the two-port in the described sensing fiber ring.
3. high sensitivity Mach Ceng Degan according to claim 2 relates to system, it is characterized in that, also comprises the second Polarization Controller, the 3rd Polarization Controller, and described sensor fibre and reference optical fiber add second, third Polarization Controller respectively.
4. one of according to claim 1-3 described high sensitivity Mach Ceng Degan relates to system, it is characterized in that, the pulse signal that described signal generator provides is that dutycycle, cycle are adjustable.
5. high sensitivity Mach Ceng Degan according to claim 4 relates to system, it is characterized in that, also comprise first wave division multiplexer, Second Wave division multiplexer that two bandwidth wavelength all equate, the common port of described first, second wavelength division multiplexer connects described the first fiber coupler, the 3rd fiber coupler by optical fiber respectively, the multiplexing end of described first, second wavelength division multiplexer is relative, adds respectively in twos described sensing fiber ring in the multiplexing end between the same channel.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103542925A (en) * | 2013-09-23 | 2014-01-29 | 华中科技大学 | Quasi-distributed optical vibrating sensing device |
| CN104729548A (en) * | 2015-02-11 | 2015-06-24 | 宁波诺可电子科技发展有限公司 | Bio-directional common optical path distributed fiber optic interferometer |
| CN105806468A (en) * | 2016-05-06 | 2016-07-27 | 华中科技大学 | Fiber bragg grating vibration sensor and detection device thereof |
| CN106546177A (en) * | 2016-10-24 | 2017-03-29 | 金陵科技学院 | It is a kind of measurement fiber coupler tail optical fiber length difference away from system and method |
| CN108036728A (en) * | 2017-12-14 | 2018-05-15 | 大连理工大学 | A kind of phase difference solution mode fiber optics displacement measuring method and instrument |
| CN110057543A (en) * | 2019-04-24 | 2019-07-26 | 暨南大学 | Based on the wavefront measurement device coaxially interfered |
| CN113091603A (en) * | 2021-04-01 | 2021-07-09 | 深圳大学 | Interference device with adjustable free spectral range |
| CN113938201A (en) * | 2021-09-18 | 2022-01-14 | 华中科技大学 | Optical fiber network |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103542925A (en) * | 2013-09-23 | 2014-01-29 | 华中科技大学 | Quasi-distributed optical vibrating sensing device |
| CN103542925B (en) * | 2013-09-23 | 2015-05-20 | 华中科技大学 | Quasi-distributed optical vibrating sensing device |
| CN104729548A (en) * | 2015-02-11 | 2015-06-24 | 宁波诺可电子科技发展有限公司 | Bio-directional common optical path distributed fiber optic interferometer |
| CN105806468A (en) * | 2016-05-06 | 2016-07-27 | 华中科技大学 | Fiber bragg grating vibration sensor and detection device thereof |
| CN106546177A (en) * | 2016-10-24 | 2017-03-29 | 金陵科技学院 | It is a kind of measurement fiber coupler tail optical fiber length difference away from system and method |
| CN106546177B (en) * | 2016-10-24 | 2019-05-31 | 金陵科技学院 | It is a kind of measurement fiber coupler tail optical fiber length difference away from system and method |
| CN108036728A (en) * | 2017-12-14 | 2018-05-15 | 大连理工大学 | A kind of phase difference solution mode fiber optics displacement measuring method and instrument |
| CN110057543A (en) * | 2019-04-24 | 2019-07-26 | 暨南大学 | Based on the wavefront measurement device coaxially interfered |
| CN113091603A (en) * | 2021-04-01 | 2021-07-09 | 深圳大学 | Interference device with adjustable free spectral range |
| CN113938201A (en) * | 2021-09-18 | 2022-01-14 | 华中科技大学 | Optical fiber network |
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