CN1444019A - Optical fibre Michelson interferometer with optic circulator - Google Patents
Optical fibre Michelson interferometer with optic circulator Download PDFInfo
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Abstract
The present invention provides a fibre-optica Michelson interferometer with optical circulator between light source and coupler of general monomode fibre-optical Michelson interferometer and respectively mounting tow 45-deg Faraday rotators before reflectors of two optical-fibre arm ends, so that it not noly resolves the problem of optical isolation of light source, but also can be use the returned optical signal to raise the signal-noise ratio and sensitivity of the sensor. Besides, said interferometer uses the Faraday rotators, and can implement the polarization extraneous interferometer formed from general monomode optical fibre, and has no need of using polarization preserving fiber and its device.
Description
Technical field:
The invention belongs to the photoelectron technology field, it is particularly related to optical fibre Michelson interferometer.
Background technology
Optical fibre Michelson interferometer and optical fiber Mach-Zehnder interferometer are two kinds of fibre optic interferometers commonly used in the photoelectron technology, can make highly sensitive interferometric optical fiber sensor, they are widely used in the measurement of fibre optic hydrophone and electric field, magnetic field, temperature, stress and so on physical quantities.Two kinds of fibre optic interferometer structures as shown in Figure 1, 2.Fig. 1 is the optical fiber Mach-Zehnder interferometer, and it is made up of two 3dB (splitting ratio is 1: 1) fiber coupler 2, two fiber arms (sensor fibre arm 4 and reference optical fiber arm 5) and phase-modulator 12, transducer 3.Fig. 2 is an optical fibre Michelson interferometer, and it is made up of for 3 groups a 3dB fiber coupler 2, two 4,5, two catoptrons 8 of fiber arm and phase-modulator 12, transducer.Light wave in the optical fibre Michelson interferometer is reflected and returns along former road after mirror 8 reflects, because twice same coupling mechanism 2 of process of light wave, in fact can regard it as belong to a class together twin-beam fibre optic interferometer and [see document: Eric Udd with the optical fiber Mach-Zehnder interferometer, Fiber Optic sensors:An introduction for Engineersand Scientists, John Wiey ﹠amp; Sons, Inc., 1991. and Brian Cushaw ﹠amp; John Dakin, Optica Fiber Sensors, Artech House Boston and ondon, 1989.].
Following two advantages have been compared with the optical fiber Mach-Zehnder interferometer with the interferometric optical fiber sensor that optical fibre Michelson interferometer is made: first, because the transducer on twice process of light wave sensor fibre arm, the phase shift that external physical quantity produces on the sensor fibre arm is the twice of optical fiber Mach-Zehnder interferometer.Therefore, the sensitivity of optical fibre Michelson interferometer sensor also is the twice of optical fiber Mach-Zehnder interferometer sensor.Second, before optical fibre Michelson interferometer catoptron 8, add a Faraday spinner 10, as shown in Figure 3, then can eliminate the signal random fading that the optical polarization random variation is brought in the general single mode fiber interferometer, constitute the polarization irrelevant fibre optic interferometer, and do not need to use expensive polarization maintaining optical fibre and polarization-maintaining fiber coupler [to see document: A.D.Kersey, M.J.Marrone ﹠amp; M.A.Davis, Poarisation-insensitive fiber optic Michelson interferometer, Vo.27, No.6, EECTRONICS ETTERS, pp.518-519,1991. and E.Brinkmeyer, Forward-backward transmission of poarization-sensitive measurement, OPTICS ETTERS, pp.575-580,1981.].
But, the problem that optical fibre Michelson interferometer exists is to have only an output terminal to be connected with photo-detector in its two output terminals, the another one output terminal links to each other with light source 1, light source 1 is a laser diode, the light that turns back to light source 1 can cause that the laser diode output spectrum changes, and exerts an influence to visibility of interference fringes.Laser diode is to feedback auroral poles sensitivity, even ten thousand/several light reflection also can produce very big influence to laser diode.Existing solution is to need to add the optoisolator of isolation greater than 50dB between light source 1 and fibre optic interferometer, stops back light to enter light source 1., though adopt optoisolator to solve back light, there is 50% light wave that has heat transfer agent to lose to the interference of light sources problem.Because two output end signals of interferometer are complementary, if this part light through light-to-current inversion, carries out difference with another output end signal of interferometer and amplifies, can eliminate the intensity noise of light source, improve the performances such as signal to noise ratio (S/N ratio) of sensor.
Summary of the invention
Patent task of the present invention provides and a kind ofly can either overcome the heat transfer agent that back light carries interference of light sources problem, the back light that can make full use of again, and feedback light is used to improve the optical fibre Michelson interferometer of band optical circulator of the signal to noise ratio (S/N ratio) of interferometric optical fiber sensor.
The object of the present invention is achieved like this: the optical fibre Michelson interferometer of band optical circulator of the present invention is made up of light source laser diode 1, three ports light rings 11,3dB fiber coupler 2, transducer 3, two fiber arms 4,5, condenser lens 9, Faraday spinner 10, catoptron 8, it is by replacing optoisolators 16, two 45 araday spinners 10 have been installed respectively before two fiber arm terminal reflectors 8 are constituted with optical circulator 11 between the light source 1 of general single mode fiber Michelson interferometer and coupling mechanism 2, and its structure as shown in Figure 5.
Essence of the present invention is between the light source 1 and coupling mechanism 2 of optical fibre Michelson interferometer, replaces optoisolator 16 with optical circulator 11.It has not only solved back light to the interference of light sources problem, and the back light that the makes full use of heat transfer agent of carrying, and back light is used to improve the signal to noise ratio (S/N ratio) of interferometric optical fiber sensor.
The principle of work of optical circulator 11 is: optical circulator 11 is nonreciprocal passive devices of a kind of multiport input and output, it make light signal can only along the regulation the port sequential delivery.Shown in Figure 3 is the principle of work block diagram of three ports light rings.Incident light from 1 port (13 among Fig. 3) can only arrive 2 ports (14 among Fig. 3), and can not enter 3 ports (15 among Fig. 3), and the light of 2 port incidents can only arrive 3 ports, and can not return 1 port.
The course of work of the present invention is: optical circulator 11 is installed between the light source 1 and coupling mechanism 2 of optical fibre Michelson interferometer, 1 port and light source 1 join, 2 ports and coupling mechanism 2 join, and turn back to light access differential amplifier 7 after the signal of directly exporting from interferometer passes through light-to-current inversion respectively of 3 ports of optical circulator 11 from fibre optic interferometer.The light that laser diode sends enters interferometer from 1 port of optical circulator 11, and the light signal that returns from interferometer can only be from 2 ports to 3 port transmission, so optical circulator plays a part optoisolator to light source.The light wave of exporting from 3 ports of optical circulator 11 is carrying the sensing physical quantity information.Light wave in two output terminal outputs of fibre optic interferometer differs 180 ° on phase place, after therefore amplifying through difference, the optical fibre Michelson interferometer of band optical circulator can be offset the intensity noise of light source light power.Therefore, this programme can improve the signal to noise ratio (S/N ratio) and the sensitivity of optical fibre Michelson interferometer type sensor.
After optical circulator 11 is installed, the Michelson interferometer forms two output terminals, if after light-to-current inversion, add an amplifier (its enlargement factor is G) at the optical circulator output terminal, make two arms signal-balanced, behind differential amplifier 7, just can eliminate the intensity noise of light source.Labor is as follows:
If the optical fibre Michelson interferometer of band optical circulator is output as
I＝I
0(A+BcosΔ) (1)
I=I
0A, B, C are constants in (C-Bcos Δ ) formula.The intensity noise of supposing light source makes light intensity output that one fluctuating I be arranged
0(1+dx), dx=dI
n/ I
0DI
nIt is the absolute value of unit bandwidth intensity noise.The interchange of interferometer is output as
DI=I
0Adx+I
0Bd (2) signal to noise ratio (S/N ratio) is Bd φ/Adx.I is surveyed phase shift and is when signal to noise ratio (S/N ratio) is 1
(1) formula two complementary signals subtract each other, and obtain
I-I '=I
0I ' signal is amplified in [(A-C)+2Bcos Δ ] (4), makes that A-GC=0, G are the enlargement factor of amplifier, and then (4) formula becomes
I-I '=I
0(B+GB) cos Δ (5) can find out that by (5) formula the intensity noise item is disappeared.Therefore the interferometer signal to noise ratio (S/N ratio) can improve greatly after difference was amplified.
Before optical fibre Michelson interferometer catoptron 8, add Faraday spinner 10, as shown in Figure 3, can offset the polarization state random variation that the ordinary optic fibre birefringence effect produces, the interference fringe contrast that the polarization state variation is caused changes less than ± 5%, and the single-mode fiber Michelson interferometer that has therefore added the Faraday spinner can be regarded the polarization irrelevant fibre optic interferometer as.
The optical fibre Michelson interferometer output terminal back light signal that links to each other with light source normally solves with optoisolator the influence of the operating characteristic of laser diode, and the present invention is used for optical circulator the junction of optical fibre Michelson interferometer light source and interferometer, not only solved the light isolating problem of light source, and this part back light signal has been used to improve the signal to noise ratio (S/N ratio) and the sensitivity of sensor.In addition, interferometer has been realized the polarization irrelevant interferometer that general single mode fiber constitutes with the Faraday spinner, and does not need with polarization maintaining optical fibre and device thereof.
Therefore good effect of the present invention is embodied in:
(1) light that has solved light source and interferometer with optical circulator is isolated; (2) signal to noise ratio (S/N ratio) and the sensitivity of sensor have been improved; (3) can solve polarization state with the Faraday spinner and change the signal dropout that causes.
Description of drawings
Fig. 1 is the structural representation of optical fiber Mach-Zehnder interferometer
Fig. 2 is the structural representation of optical fibre Michelson interferometer
Fig. 3 is the structural representation of the optical fibre Michelson interferometer of polarization irrelevant
Fig. 4 is the structural representation of three port photocirculators
The structural representation of the optical fibre Michelson interferometer of the band optical circulator that Fig. 5 is
In the drawings, the 1st, light source laser diode, the 2nd, fiber coupler, the 3rd, transducer, the 4th, sensor fibre arm, the 5th, reference optical fiber arm, the 6th, photodiode, the 7th, differential amplifier, the 8th, catoptron, the 9th, condenser lens, the 10th, Faraday spinner, the 11st, optical circulator, the 12nd, phase-modulator, the 13rd, optical circulator 1 port, the 14th, optical circulator 2 ports, the 15th, optical circulator 3 ports, the 16th, optoisolator.
Embodiment:
The optical fibre Michelson interferometer of band optical circulator as shown in Figure 5.Optical circulator 11 can be the product of CIR-A-1-3-1-0 with the model of Leona Information Technology company limited.Ignore the insertion loss of fiber coupler 2 and other optical element, the reflectivity of establishing catoptron 8 is 100%, and the interferometer visibility is 1.The specific embodiment of the invention is by replacing optoisolator 16, all added 10 realizations of 45 araday spinners before two fiber arm terminal reflectors 8 with optical circulator 11 between general single mode fiber Michelson interferometer light source 1 and the coupling mechanism 2, and its structure as shown in Figure 5.If the encapsulation of interferometer makes sensor fibre arm and reference optical fiber arm isometric and be in the same external interference field, the environment thermal distortion is identical at the sensor fibre arm with the phase shift that the reference optical fiber arm produces with vibration, and the phase shift noise of environmental perturbation generation will disappear mutually.
Can obtain conclusion from the specific embodiment of the present invention: the optical fibre Michelson interferometer of band optical circulator of the present invention has at first solved the isolation and the both-end output difference of light source and has amplified raising interferometer signal to noise ratio (S/N ratio) problem; Secondly, light wave passes through transducer twice, and the optical fibre Michelson interferometer transducer sensitivity is the twice of optical fiber Mach-Zehnder interferometer.In addition, to add the polarization irrelevant fibre optic interferometer that the Faraday spinner constitutes be that the optical fiber Mach-Zehnder interferometer can not be accomplished to optical fibre Michelson interferometer.Therefore, the optical fibre Michelson interferometer performance of band optical circulator of the present invention is better than traditional double beam interferometer.
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101325455B (en) * | 2008-07-30 | 2010-12-29 | 哈尔滨工程大学 | A Sensing and Demodulating Device for Dual Reference Length Low Coherence Optical Fiber Ring Network |
| CN101957477A (en) * | 2010-05-31 | 2011-01-26 | 哈尔滨工程大学 | Polarization-preserving type fiber integrated Michelson interferometer |
| CN101963515A (en) * | 2010-09-29 | 2011-02-02 | 哈尔滨工程大学 | Distributed Michelson optical fibre white light interference sensing device |
| 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 |
| CN102401670A (en) * | 2011-04-06 | 2012-04-04 | 杭州安远科技有限公司 | Optical fiber interferometry system for reducing optical fiber birefringence influence |
| CN103261835A (en) * | 2010-10-14 | 2013-08-21 | 森西斯光纤公司 | Variable sensitivity interferometer systems |
| CN104180832A (en) * | 2013-05-24 | 2014-12-03 | 无锡万润光子技术有限公司 | Distributed orthogonal vector disturbance sensing system based on four-core optical fiber |
| CN104180831A (en) * | 2013-05-24 | 2014-12-03 | 无锡万润光子技术有限公司 | Sensitivity-enhanced optical time domain reflection distributed Michelson interferometer based on two-core optical fiber |
| CN104180830A (en) * | 2013-05-24 | 2014-12-03 | 无锡万润光子技术有限公司 | Distributed optical fiber fizeau interferometer based on light time domain reflection principle |
| CN104897302A (en) * | 2015-06-19 | 2015-09-09 | 中国计量学院 | Temperature sensor of photonic crystal optical fiber Michelson interferometer based on corrosion processing |
| CN104389588B (en) * | 2014-11-14 | 2017-02-22 | 大连理工大学 | Single-light-source optical fiber distribution temperature and fixed-point pressure measurement system and method |
-
2002
- 2002-03-08 CN CN 02113431 patent/CN1444019A/en active Pending
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101325455B (en) * | 2008-07-30 | 2010-12-29 | 哈尔滨工程大学 | A Sensing and Demodulating Device for Dual Reference Length Low Coherence Optical Fiber Ring Network |
| CN101957477A (en) * | 2010-05-31 | 2011-01-26 | 哈尔滨工程大学 | Polarization-preserving type fiber integrated Michelson interferometer |
| CN101963515A (en) * | 2010-09-29 | 2011-02-02 | 哈尔滨工程大学 | Distributed Michelson optical fibre white light interference sensing device |
| CN103261835A (en) * | 2010-10-14 | 2013-08-21 | 森西斯光纤公司 | Variable sensitivity interferometer systems |
| CN103261835B (en) * | 2010-10-14 | 2016-12-21 | 超音速光纤公司 | Sensitivity variable interferometer system |
| CN102401670A (en) * | 2011-04-06 | 2012-04-04 | 杭州安远科技有限公司 | Optical fiber interferometry system for reducing optical fiber birefringence influence |
| 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 |
| CN104180832A (en) * | 2013-05-24 | 2014-12-03 | 无锡万润光子技术有限公司 | Distributed orthogonal vector disturbance sensing system based on four-core optical fiber |
| CN104180831A (en) * | 2013-05-24 | 2014-12-03 | 无锡万润光子技术有限公司 | Sensitivity-enhanced optical time domain reflection distributed Michelson interferometer based on two-core optical fiber |
| CN104180830A (en) * | 2013-05-24 | 2014-12-03 | 无锡万润光子技术有限公司 | Distributed optical fiber fizeau interferometer based on light time domain reflection principle |
| CN104389588B (en) * | 2014-11-14 | 2017-02-22 | 大连理工大学 | Single-light-source optical fiber distribution temperature and fixed-point pressure measurement system and method |
| CN104897302A (en) * | 2015-06-19 | 2015-09-09 | 中国计量学院 | Temperature sensor of photonic crystal optical fiber Michelson interferometer based on corrosion processing |
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