CN101257348B - Heterodyne type differential interference optical fiber system - Google Patents
Heterodyne type differential interference optical fiber system Download PDFInfo
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- CN101257348B CN101257348B CN2008100355802A CN200810035580A CN101257348B CN 101257348 B CN101257348 B CN 101257348B CN 2008100355802 A CN2008100355802 A CN 2008100355802A CN 200810035580 A CN200810035580 A CN 200810035580A CN 101257348 B CN101257348 B CN 101257348B
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Abstract
The invention belongs to optical fibre technique field, particularly to a heterodyne type differential interference method and optical fiber system. A frequency shifter is used in a differential light path to form the differential interference to get one heterodyne signal, therefore effectively overcoming the mismatch of the multiplex zero-difference detection signal, enhancing the accuracy of data processing, and simplifying the process of the data. The optical fibre interference system of the invention has small volume, light weight, can realize the measuring of the dynamic signal such as velocity, pressure, strain, acoustic wave, earthquake wave, etc., and the functions of optic switch and filter in all-optical communication network.
Description
Technical field
The invention belongs to the optical fiber technology field, be specifically related to a kind of fiber optic interferometric system.
Background technology
Differential type interferometer structure has two bundle laser of a fixed response time, and induction can cause the information of phase change, forms differential interferometry.The typical application of differential interferometer is any reflecting surface velocity interferometer of researcher Barker system in 1972 at present; This system has developed perfect at present; 1996, Israel scientist Levin proposed similar all optical fibre structure, had injected new vitality for the differential type interferometer tests the speed.Differential interferometer need be constructed multi beam and interfered the output signal, recovers interferometric phase through multiple signals, yet; Because in actual the use, amplitude, phase information are easy to change with external environment between the multi-beam signal, cause interference fringe to recover unstable; Error appears; The work of signal processing automation is also made slow progress, and the scientific worker in use needs the more knowledge background, and this also is unfavorable for this The Application of Technology.The mode that adopts difference interference to combine with difference on the light path of the present invention, phase signal is extracted on one road heterodyne signal and launches, and has effectively overcome the do not match problem of the phase bit recovery unstability that causes of multiple signals.This technology can be widely used in sensing and optical communication field.
Summary of the invention
The object of the present invention is to provide a kind of heterodyne system difference fiber optic interferometric system that avoids the destabilization problems that the multiple signals interference signal do not match and cause.
Heterodyne system differential interference method provided by the invention is to introduce a frequency shifter in the wherein optical interference circuit in the differential interferometry light path, forms the heterodyne system differential interferometry, obtains one road difference interference signal, and the signal source of reducing as phase place successively.Based on said method, use fiber optic passive device and modulator configuration optical interference circuit, form optical fiber type differential interferometry system.
If the phase modulated that extraneous phase place causes is s (t), then the output signal of traditional differential interferometer can be expressed as
I
1＝A
1(t)+B
1(t)sinΦ(t) (1)
I
2＝A
2(t)+B
2(t)cosΦ(t) (2)
Wherein, Φ (t)=s (t)-s (t-τ), τ is the difference amount of delay in the light path.
The demodulation part of differential interferometer obtains the signal B that two-way has 90 degree phase differences through signal processing
1(t) B
2(t) sin Φ (t), B
1(t) B
2(t) cos Φ (t) through differential multiplication cross integration operation or phase unwrapping operation, can obtain interferometric phase Φ (t), and then obtain phase place s (t), and the method also is the demodulation mode that typical homodyne is interfered.Before carrying out this operation, in the interference signal, A
1(t), A
2(t), B
1(t), B
2(t) relation between must be confirmed through the Third Road signal at least; In multiple signals amplitude, the phase difference often with environment for use unmatched phenomenon appears; Cause interference fringe to recover unstable; Error occurs, the work of signal processing automation is also made slow progress, and therefore is badly in need of more perfect solution.The heterodyne system differential interference method that the present invention proposes addresses this problem exactly, through the method, obtains one road differential interferometry signal, can be expressed as
I＝A(t)+B(t)sin[ωt+Φ(t)+θ]
Wherein ω is the difference frequency of coherent laser, and θ is the static initial phase difference of coherent beam.
Through this one road signal; Use typical heterodyne signal demodulation method, can construct the orthogonal signalling of amplitudes such as two-way has, through differential multiplication cross integration operation or phase unwrapping operation; Can obtain interferometric phase Φ (t); And then obtaining phase place s (t), the core of this invention is in light path, to have used frequency shifter, has formed difference interference.
Constructed heterodyne system difference fiber optic interferometric system based on above-mentioned heterodyne system differential interference method, concrete like Fig. 1, shown in Figure 2.
Interference system described in Fig. 1, it by laser 1,1 * 2 fiber coupler 2, postpone optical fiber cable 3, heterodyne demodulation detector 4, frequency shifter 7,1 * 3 fiber coupler 8, optical transceiver 9 and tested surface 10 and form.Wherein, Laser 1 as light source is aimed at 1 * 2 fiber coupler 2; 2 ports havings 5 and another port 6 of 1 * 2 fiber coupler; 8 ports havings 11 of 1 * 3 fiber coupler, another port 12, another port 13, its middle port 5 connection delay optical fiber cables 3 are connected with frequency shifter 7 and with 1 * 3 fiber coupler, 8 port ones 1; The another port 6 of 1 * 2 fiber coupler 2 is connected with 1 * 3 fiber coupler another port 13; The another port 12 of 1 * 3 fiber coupler is connected with heterodyne demodulation detector 4.
So from light source---detector sees that the interfering beam of formation is following:
The light that laser 1 sends, after 2 beam split of 1 * 2 fiber coupler, the light of port 5; Through postponing optical fiber cable 3, get into 1 * 3 fiber coupler through port one 1 again, through optical transceiver 9; Shine on the tested surface 10, after reflection, get into beam split in 1 * 3 fiber coupler 8 through optical transceiver 9; The light of another port 12 gets into the heterodyne demodulation detector, and this is the 1st light beam; The light that laser 1 sends, after 2 beam split of 1 * 2 fiber coupler, the light of another port 6 is through frequency shifter 7; Another port 13 through 1 * 3 fiber coupler 8 connects, and gets into 1 * 3 fiber coupler 8, shines on the tested surface 10 through optical transceiver 9; After the reflection, get into 1 * 3 fiber coupler 8 through optical transceiver 9, after beam split; The entering heterodyne demodulation detector of another port 12, this is the 2nd light beam.Two light beams is the heterodyne coherent beam, restores information measured through the heterodyne demodulation detector.
This heterodyne system difference fiber optic interferometric system; Adopt one 1 * 2 fiber coupler and one 1 * 3 fiber coupler; The fiber coupler port number here should not be construed as the restriction of native system, for example changes 1 * 2 fiber coupler 2 into 2 * 2 fiber couplers and still drops within protection scope of the present invention.
This heterodyne system difference fiber optic interferometric system, with a frequency shifter, this frequency shifter refers to any device that can realize that laser center wavelength moves, the for example acousto-optic frequency shifters of acousto-optic principle.
This heterodyne system difference fiber optic interferometric system adopts a heterodyne demodulation detector.
This heterodyne system difference fiber optic interferometric system; Adopting optical transceiver and tested surface to constitute phase modulation system, also can be any Intrinsical fibre optic phase modulator, such as; On elastomer, twine a circle or multiturn optical fiber, utilize the elasto-optical effect of optical fiber to realize phase modulated; Also can be the crystal that optical index can change with the applied voltage signal, like lithium columbate crystal etc.
This heterodyne system difference fiber optic interferometric system, used optical fiber is monomode fiber or multimode fiber.
This heterodyne system difference fiber optic interferometric system, fiber coupler adopts on-plane surface coupler or plane coupler.
This heterodyne system difference fiber optic interferometric system; Used laser works wavelength is semiconductor laser diode or the semiconductor light-emitting-diode laser of 1.31 μ m or 1.55 μ m; Perhaps Distributed Feedback Laser, the perhaps short wavelength laser of wavelength 850nm or gas laser.
This heterodyne system difference fiber optic interferometric system, the connection between being connected of fiber coupler and optical fiber, the optical fiber adopts the mode of fusing to connect, being connected of light source and optical fiber, photodetector and optical fiber be connected the connection of employing wire jumper.
According to main idea of the present invention, can know:
Among Fig. 1, laser 1 can exchange with heterodyne demodulation detector 4, forms interference system, drops within the inventor's the protection range.
Among Fig. 2, laser 1 can exchange with heterodyne demodulation detector 4, forms interference system, drops within the inventor's the protection range.
Description of drawings
Fig. 1 heterodyne differential type of the present invention fiber optic interferometric system schematic.
Fig. 2 is and the similar heterodyne differential type of Fig. 1 fiber optic interferometric system schematic.
Fig. 3 is the test data figure of present embodiment.
Label among the figure: 1 is laser, and 2 is 1 * 2 fiber coupler, 4 heterodyne demodulation detectors; 3 for postponing optical fiber cable, and 5,6 is 2 ports of 1 * 2 fiber coupler, and 7 is frequency shifter; 8 is 1 * 3 fiber coupler; 9 is light probe, and 10 is tested surface, and 11,12,13 is 3 ports of 1 * 3 fiber coupler.
Embodiment
In the present embodiment; Used laser 1 is the Distributed Feedback Laser that nine divisions of China in remote antiquity, Sichuan photoelectricity company produces; Acousto-optic frequency shifters 7 is used the optical fiber coupled mode acousto-optic modulator of the M040-8J-FxS model of Britain Gooch & Housego; Heterodyne demodulation detector 4 is that 44 models of being produced are the InGaAs photodetector of GT322C500 and are furnished with demodulator circuit, and coupler and optical transceiver are single-mode optical-fibre coupler and the single mode collimater that Wuhan post and telecommunications research institute produces.Used optical fiber is produced in usa " healthy and free from worry " G652 type monomode fiber.Light source is that the FC/APC wire jumper is connected with interference system, interference system with the connected mode of detector.Adopt the mode of Fig. 1 to fuse, link together, use the Huo Bujinsen depression bar to produce the high-speed impact motion, the velocity test result of realization is as shown in Figure 3.
Claims (4)
1. a heterodyne system difference fiber optic interferometric system is characterized in that said system is made up of laser (1), 1 * 2 fiber coupler (2), delay optical fiber cable (3), heterodyne demodulation detector (4), frequency shifter (7), 1 * 3 fiber coupler (8), optical transceiver (9) and tested surface (10); Wherein, Laser (1) as light source is aimed at 1 * 2 fiber coupler (2); 1 * 2 fiber coupler (2) has first port (5) and second port (6); 1 * 3 fiber coupler (8) has the 3rd port (11), the 4th port (12), five-port (13), and wherein first port (5) connection delay optical fiber cable (3) is connected with frequency shifter (7) and with 1 * 3 fiber coupler (8) the 3rd port (11); Second port (6) of 1 * 2 fiber coupler (2) is connected with 1 * 3 fiber coupler five-port (13); 1 * 3 fiber coupler the 4th port (12) is connected with heterodyne demodulation detector (4); The light path of system is: the light that laser (1) sends, and after 1 * 2 fiber coupler (2) beam split, the light of first port (5); Through postponing optical fiber cable (3) and frequency shifter (7), get into 1 * 3 fiber coupler (8) through the 3rd port (11) again, through optical transceiver (9); Shine on the tested surface (10), after reflection, get into beam split in 1 * 3 fiber coupler (8) through optical transceiver (9); The light of the 4th port (12) gets into the heterodyne demodulation detector, and this is the 1st light beam; The light that laser (1) sends, after 1 * 2 fiber coupler (2) beam split, the light of second port (6) connects through the five-port (13) of 1 * 3 fiber coupler (8); Get into 1 * 3 fiber coupler (8), shine on the tested surface (10), after the reflection through optical transceiver (9); Get into 1 * 3 fiber coupler (8) through optical transceiver (9); After beam split, the entering heterodyne demodulation detector of the 4th port (12), this is the 2nd light beam; Two light beams is the heterodyne coherent beam, restores information measured through the heterodyne demodulation detector;
Perhaps said system is made up of laser (1), 1 * 2 fiber coupler (2), delay optical fiber cable (3), heterodyne demodulation detector (4), frequency shifter (7), 1 * 3 fiber coupler (8), optical transceiver (9) and tested surface (10); Wherein, Laser (1) as light source is aimed at 1 * 2 fiber coupler (2); 1 * 2 fiber coupler (2) has first port (5) and second port (6); 1 * 3 fiber coupler (8) has the 3rd port (11), the 4th port (12), five-port (13), wherein first port (5) connection delay optical fiber cable (3) and be connected with 1 * 3 fiber coupler (8) the 3rd port (11); Second port (6) of 1 * 2 fiber coupler (2) connects frequency shifter (7) and is connected with 1 * 3 fiber coupler five-port (13); The 4th port (12) of 1 * 3 fiber coupler is connected with heterodyne demodulation detector (4); The light path of system is: the light that laser (1) sends, and after 1 * 2 fiber coupler (2) beam split, the light of first port (5); Through postponing optical fiber cable (3), get into 1 * 3 fiber coupler (8) through the 3rd port (11) again, through optical transceiver (9); Shine on the tested surface (10), after reflection, get into beam split in 1 * 3 fiber coupler (8) through optical transceiver (9); The light of the 4th port (12) gets into the heterodyne demodulation detector, and this is the 1st light beam; The light that laser (1) sends, after 1 * 2 fiber coupler (2) beam split, the light of second port (6) is through frequency shifter (7); Five-port (13) through 1 * 3 fiber coupler (8) connects, and gets into 1 * 3 fiber coupler (8), shines on the tested surface (10) through optical transceiver (9); After the reflection, get into 1 * 3 fiber coupler (8) through optical transceiver (9), after beam split; The entering heterodyne demodulation detector of the 4th port (12), this is the 2nd light beam; Two light beams is the heterodyne coherent beam, restores information measured through the heterodyne demodulation detector.
2. heterodyne system difference fiber optic interferometric according to claim 1 system is characterized in that the used optical fiber of system is monomode fiber or multimode fiber.
3. heterodyne system difference fiber optic interferometric according to claim 1 system is characterized in that fiber coupler adopts on-plane surface coupler or plane coupler.
4. heterodyne system difference fiber optic interferometric according to claim 1 system; It is characterized in that said laser is that operation wavelength is semiconductor laser diode or the semiconductor light-emitting-diode laser of 1.31 μ m or 1.55 μ m; Perhaps Distributed Feedback Laser; Perhaps wavelength is the short wavelength laser of 850nm, perhaps gas laser.
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| CN103822655B (en) * | 2014-02-19 | 2016-04-27 | 西北工业大学 | A kind of device measuring large depth of field nanosecond scale Fast Process |
| CN104132677A (en) * | 2014-07-24 | 2014-11-05 | 中国科学院半导体研究所 | Heterodyne interference type optical fiber sensing time division multiplexing system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1431462A (en) * | 2003-02-28 | 2003-07-23 | 清华大学 | Frequency shift without chromatic aberration of wideband light source and device generation interferential heterodgne signal |
| US6788420B1 (en) * | 2002-01-29 | 2004-09-07 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Heterodyne interferometer with a phase modulated source |
| CN1844868A (en) * | 2006-04-28 | 2006-10-11 | 清华大学 | Method and apparatus for measuring laser wavelength by heterodyne interference method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US6788420B1 (en) * | 2002-01-29 | 2004-09-07 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Heterodyne interferometer with a phase modulated source |
| CN1431462A (en) * | 2003-02-28 | 2003-07-23 | 清华大学 | Frequency shift without chromatic aberration of wideband light source and device generation interferential heterodgne signal |
| CN1844868A (en) * | 2006-04-28 | 2006-10-11 | 清华大学 | Method and apparatus for measuring laser wavelength by heterodyne interference method |
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