CN102650524A - Differential dual-interference type closed loop fiber optic gyroscope based on birefringence modulation of wide frequency light source - Google Patents

Differential dual-interference type closed loop fiber optic gyroscope based on birefringence modulation of wide frequency light source Download PDF

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CN102650524A
CN102650524A CN2012101239896A CN201210123989A CN102650524A CN 102650524 A CN102650524 A CN 102650524A CN 2012101239896 A CN2012101239896 A CN 2012101239896A CN 201210123989 A CN201210123989 A CN 201210123989A CN 102650524 A CN102650524 A CN 102650524A
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China
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fiber optic
light source
polarization beam
beam apparatus
modulator
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CN2012101239896A
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Chinese (zh)
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CN102650524B (en
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杜士森
张祖琛
李彦
宋凝芳
金靖
肖智
李志敏
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北京航空航天大学
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Abstract

The invention discloses a differential dual-interference type closed loop fiber optic gyroscope based on birefringence modulation of a wide frequency light source. The differential dual-interference type closed loop fiber optic gyroscope comprises the light source, a first coupler, a second coupler, a first polarization beam splitter, a first modulator, a second modulator, a second polarization beam splitter, a fiber optic loop, a third polarization beam splitter, a first detector and a second detector. The differential dual-interference type closed loop fiber optic gyroscope has the advantages that closed loop control of the differential dual-interference type fiber optic gyroscope is realized; as the wide frequency light source with a very weak coherence characteristic is adopted, strong noise brought by various stray wave interference caused by a strong coherence characteristic of a laser light source is avoided; a SAGNAC effect is doubled; and the differential dual-interference type closed loop fiber optic gyroscope has a mature technical foundation and can satisfy a relatively high precision requirement.

Description

The two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference based on wide spectrum light source birefringence modulation

Technical field

The present invention relates to a kind of closed loop difference pair interferometric fiber optic gyroscopes of under the constant condition of fiber optic loop area and fiber lengths, realizing multiplication of SAGNAC effect and closed-loop control, belong to the fiber-optics gyroscope field.

Background technology

Optical fibre gyro is as a kind of very rapidly novel inertia angular-rate sensor of development, and is with its distinctive technology and performance advantage, high like structure of whole solid state, reliability, the life-span is long; Toggle speed is fast, and the response time is short; Measurement range is big, wide dynamic range; Shock resistance, vibration, resistance to chemical attack; Volume is little, in light weight, cost is low; Be fit to produce in enormous quantities etc., be widely used in each field.

General in the world optical fibre gyro form is single interfere type; Promptly utilize fast or slow axis realization SAGNAC interferometer of a cover light path (polarization-maintaining fiber coil), through resolving the SAGNAC phase shift that the carrier rotation causes according to the interference between the main wave train of two bundles of (CW), (CCW) propagation counterclockwise clockwise respectively.Though this interferometer is simple in structure; But continuous expansion along with the optical fibre gyro application; Contradiction between its volume, weight and the precision becomes increasingly conspicuous, and with existing technology and technological level, is keeping under the prerequisite of precision; Further reduce volume, the very difficult realization breakthrough of weight, vice versa.

The two interferometric fiber optic gyroscopes of difference are in a cover light path (polarization-maintaining fiber coil); Utilize its fast axle and slow axis to realize a SAGNAC interferometer respectively; The output of this two-way interferometer presents difference form, and after resolving through difference, the SAGNAC effect is doubled.At present; What the two interferometric fiber optic gyroscopes of difference adopted is open loop policy; Phase differential is very big between the light wave of every road interferometer output; So must utilize the good laser of coherence as light source realizing the interference between these light waves, but this has caused the interference between the various stray waves, thus the noise of the two interferometric fiber optic gyroscopes of open loop difference is big and be difficult to suppress.

Summary of the invention

To the objective of the invention is in order addressing the above problem, to propose a kind of closed loop difference pair interferometric fiber optic gyroscopes of under the constant condition of fiber optic loop area and fiber lengths, realizing multiplication of SAGNAC effect and closed-loop control.

The two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference based on wide spectrum light source birefringence modulation comprise light source, first coupling mechanism, second coupling mechanism, first polarization beam apparatus, first modulator, second modulator, second polarization beam apparatus, fiber optic loop, the 3rd polarization beam apparatus, first detector and second detector;

The A of the light source and first coupling mechanism 1End is fused to fusing point O with 45 ° 1, the C of first coupling mechanism 1The A of the port and second coupling mechanism 2Port is fused to fusing point O with 0 ° 2, the C of second coupling mechanism 2The port and first polarization beam apparatus are fused to fusing point O with 0 ° 3, two output terminals of first polarization beam apparatus are fused to fusing point O with an end of first modulator and second modulator with 0 ° respectively 4, O 5, the other end of first modulator and second modulator is fused to fusing point O with two input ends of second polarization beam apparatus with 0 ° respectively 6, O 7, an end of the output terminal of second polarization beam splitting and polarization-maintaining fiber coil is fused to fusing point O with 0 ° 8, the D of second coupling mechanism 2End is fused to fusing point O with an other end of fiber optic loop with 0 ° 9, the B of first coupling mechanism 1End is fused to fusing point O with the input end of the 3rd polarization beam apparatus with 0 ° 10, two output terminals of the 3rd polarization beam apparatus are fused to an O with first detector and second detector with 0 ° respectively 11, O 12

By wide spectrum light source, polarization-maintaining coupler, polarization beam apparatus; Modulator, polarization-maintaining fiber coil, detector constitutes; Wide spectrum light source output polarization light has produced through 45 ° of cross-couplings that two amplitudes equate, the vertical light wave in polarization direction; Propagate along fast, the slow axis of optical fiber respectively, make the two-way light wave separately and in fiber optic loop, propagate through polarization beam apparatus relatively independently, thereby realize two cover optical interference circuits with a set of equipment; The i.e. parallel running of the closed loop interference type optical fiber gyroscope of two cover technology maturations finally realizes doubling the SAGNAC effect through two-way output signal is carried out calculus of differences.

Advantage of the present invention:

(1) realized the closed-loop control of the two interference type optical fiber gyroscopes of difference;

(2) adopted the very weak wide spectrum light source of coherence, the various stray waves of having avoided laser light source strength coherence to cause are interfered and the very noisy that brings;

(3) the SAGNAC effect doubles;

(4) have the proven technique basis, can reach higher accuracy requirement;

Description of drawings

Fig. 1 is the two interference type optical fiber gyroscope structured flowcharts of closed loop difference;

Fig. 2 is fusing point O 1Place's light wave synoptic diagram;

Fig. 3 is the wide spectrum light source coherence function;

Fig. 4 is the modulation waveform that applies on the modulator;

Fig. 5 is the first detector place interference light intensity and phase modulation relation (fast axle optical interference circuit);

Fig. 6 is the second detector place interference light intensity and phase modulation relation (slow axis optical interference circuit).

Among the figure:

The 1-light source 2-first coupling mechanism 3-second coupling mechanism

The 4-first polarization beam apparatus 5-first modulator 6-second modulator

The 7-second polarization beam apparatus 8-fiber optic loop 9-the 3rd polarization beam apparatus

The 10-first detector 11-second detector

Embodiment

To combine accompanying drawing that the present invention is done further detailed description below.

The present invention is the two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference based on wide spectrum light source birefringence modulation; As shown in Figure 1, comprise light source 1, first coupling mechanism 2, second coupling mechanism 3, first polarization beam apparatus 4, first modulator 5, second modulator 6, second polarization beam apparatus 7, fiber optic loop 8, the 3rd polarization beam apparatus 9, first detector 10 and second detector 11;

The A of the light source 1 and first coupling mechanism 2 1End is fused to fusing point O with 45 ° 1, the C of first coupling mechanism 2 1The A of the port and second coupling mechanism 3 2Port is fused to fusing point O with 0 ° 2, the C of second coupling mechanism 3 2The port and first polarization beam apparatus 4 are fused to fusing point O with 0 ° 3, two output terminals of first polarization beam apparatus 4 are fused to fusing point O with an end of first modulator 5 and second modulator 6 with 0 ° respectively 4, O 5, the other end of first modulator 5 and second modulator 6 is fused to fusing point O with two input ends of second polarization beam apparatus 7 with 0 ° respectively 6, O 7, an end of the output terminal of second polarization beam splitting 7 and polarization-maintaining fiber coil 8 is fused to fusing point O with 0 ° 8, the D of second coupling mechanism 3 2End is fused to fusing point O with an other end of fiber optic loop 8 with 0 ° 9, the B of first coupling mechanism 2 1End is fused to fusing point O with the input end of the 3rd polarization beam apparatus 9 with 0 ° 10, two output terminals of the 3rd polarization beam apparatus 9 are fused to an O with first detector 10 and second detector 11 with 0 ° respectively 11, O 12

In the present invention, light source 1 is selected the wide range SLD light source with high-polarization for use, and model is SLD13; It is the PMC-X-2*2-1550-50/50-0-4X type polarization-maintaining coupler of Shenzhen Lang Guang company that coupling mechanism (first coupling mechanism 2 and second coupling mechanism 3) is selected polarization-maintaining coupler, model for use; Polarization beam apparatus (first polarization beam apparatus 4, second polarization beam apparatus 7 and the 3rd polarization beam apparatus 9) is selected the PBS-1*2-1550-S-N type polarization beam apparatus of Tianjin high beacon Science and Technology Ltd. for use; It is PMS1522-CX-TL that modulator (first modulator 5 and second modulator 6) is selected straight wave guide modulator, model for use; Fiber optic loop 8 is selected polarization-maintaining fiber coil for use; Detector (first detector 10 and second detector 11) is selected the PFTM901-001 type photodetector of Wuhan Telecommunication Devices Co., Ltd for use.

Light source 1 polarization light output E is at fusing point O 1Amplitude equates because 45 ° of cross-couplings have produced at the place, mutually perpendicular two wave train X in polarization direction and Y, and as shown in Figure 2 (wherein fast axle is the quick shaft direction of polarization maintaining optical fibre, representes with X; Slow axis is the slow-axis direction of polarization maintaining optical fibre, representes with Y); X, these two wave trains of Y are propagated along fast, the slow axis of polarization maintaining optical fibre respectively; Be separated into two independently light paths through first coupling mechanism 2 and second coupling mechanism, 3 backs by first polarization beam apparatus 4 successively; Through convergeing in the same polarization maintaining optical fibre via second polarization beam apparatus 7 again behind first modulator 5 and second modulator 6, propagate along fast, slow axis separately and enter into fiber optic loop 8 respectively; Characteristic based on polarization maintaining optical fibre; The two-way light wave will keep polarization state separately to propagate in optical fiber with different speed; The coherence of considering wide spectrum light source 1 again is (as shown in Figure 3; Wide spectrum light source normalization degree of coherence reduces rapidly with the increase of optical path difference; Promptly have only the two-beam of optical path difference in certain-length just can interfere, can effectively reduce the relevant error that Rayleigh scattering, polarization cross coupling and Kerr effect etc. dorsad cause) and integrally-built fiber lengths, two wave trains are at the output terminal (B of first coupling mechanism 2 1Port) can not overlap; Tangible interference can not take place each other yet; So can regard the two as two separate optical interference circuits, behind the 3rd polarization beam apparatus 9,, promptly realize the relatively independent optical interference circuit of two covers with a set of equipment respectively by first detector 10 and second detector, 11 output signals; Closed loop modulation technique to the ripe single interference type optical fiber gyroscope of each light path utilization obtains phase information respectively; On first modulator 5 and second modulator 6, add modulation waveform as shown in Figure 4 respectively, promptly respectively two separate light paths modulated that phase modulation is Φ with periodic square wave mM0± pi/2; The two-way interference waveform that obtains thus is respectively like Fig. 5, shown in Figure 6; What wherein Fig. 5 coordinate axis top was represented is that first via interferometer interference light intensity changes by the cosine rule; The bottom is the phase modulation (PM) waveform that adds, and the output waveform of first detector 10 is shown in the upper right corner, and output was straight line when gyro was static; Gyro when rotation working point is moved, output become one with the square-wave signal of square wave with frequency; What Fig. 6 coordinate axis top was represented is that No. the second interferometer interference light intensity changes by the cosine rule; The bottom is the phase modulation (PM) waveform that adds, and the output waveform of second detector 11 is shown in the upper right corner, and output was straight line when gyro was static; The working point is moved during the gyro rotation; Output become one with square wave with frequently square-wave signal, again the two-way result is carried out calculus of differences, thus the multiplication of realization SAGNAC effect under the constant condition of fiber optic loop area and fiber lengths.

Claims (7)

1. two interfere type closed-loop fiber optic gyroscope appearance of the difference based on wide spectrum light source birefringence modulation; It is characterized in that, comprise light source, first coupling mechanism, second coupling mechanism, first polarization beam apparatus, first modulator, second modulator, second polarization beam apparatus, fiber optic loop, the 3rd polarization beam apparatus, first detector and second detector;
The A of the light source and first coupling mechanism 1End is fused to fusing point O with 45 ° 1, the C of first coupling mechanism 1The A of the port and second coupling mechanism 2Port is fused to fusing point O with 0 ° 2, the C of second coupling mechanism 2The port and first polarization beam apparatus are fused to fusing point O with 0 ° 3, two output terminals of first polarization beam apparatus are fused to fusing point O with an end of first modulator and second modulator with 0 ° respectively 4, O 5, the other end of first modulator and second modulator is fused to fusing point O with two input ends of second polarization beam apparatus with 0 ° respectively 6, O 7, an end of the output terminal of second polarization beam splitting and polarization-maintaining fiber coil is fused to fusing point O with 0 ° 8, the D of second coupling mechanism 2End is fused to fusing point O with an other end of fiber optic loop with 0 ° 9, the B of first coupling mechanism 1End is fused to fusing point O with the input end of the 3rd polarization beam apparatus with 0 ° 10, two output terminals of the 3rd polarization beam apparatus are fused to an O with first detector and second detector with 0 ° respectively 11, O 12
2. the two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference based on wide spectrum light source birefringence modulation according to claim 1 is characterized in that described light source is selected the wide range SLD light source with high-polarization for use, and model is SLD13.
3. the two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference according to claim 1 based on wide spectrum light source birefringence modulation; It is characterized in that; Described first coupling mechanism and second coupling mechanism are selected polarization-maintaining coupler for use, and model is a PMC-X-2*2-1550-50/50-0-4X type polarization-maintaining coupler.
4. the two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference according to claim 1 based on wide spectrum light source birefringence modulation; It is characterized in that described first polarization beam apparatus, second polarization beam apparatus and the 3rd polarization beam apparatus are selected PBS-1*2-1550-S-N type polarization beam apparatus for use.
5. the two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference based on wide spectrum light source birefringence modulation according to claim 1 is characterized in that described first modulator and second modulator are selected the straight wave guide modulator for use, and model is PMS 1522-CX-TL.
6. the two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference based on wide spectrum light source birefringence modulation according to claim 1 is characterized in that described fiber optic loop is selected polarization-maintaining fiber coil for use.
7. the two interfere type closed-loop fiber optic gyroscope appearance of a kind of difference based on wide spectrum light source birefringence modulation according to claim 1 is characterized in that described first detector and second detector are selected PFTM901-001 type photodetector for use.
CN201210123989.6A 2012-04-25 2012-04-25 Differential dual-interference type closed loop fiber optic gyroscope based on birefringence modulation of wide frequency light source CN102650524B (en)

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CN104075705A (en) * 2014-06-26 2014-10-01 中航捷锐(北京)光电技术有限公司 Optical fiber gyroscope for improving velocity sensitivity
CN104075704A (en) * 2014-06-26 2014-10-01 中航捷锐(北京)光电技术有限公司 Digital closed loop optical fiber gyroscope with double-interferometer system
CN104236537A (en) * 2014-09-12 2014-12-24 北京航空航天大学 Light source intensity noise suppression digital double closed-loop method based on intensity modulator
CN104613985A (en) * 2015-02-12 2015-05-13 重庆华渝电气集团有限公司 Method for improving interchangeability of fiber-optic gyroscope in navigation system
CN108387787A (en) * 2018-01-16 2018-08-10 清华大学 A kind of integrated common path interference electric field measurement system for eliminating polarization correlated noise

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104075705A (en) * 2014-06-26 2014-10-01 中航捷锐(北京)光电技术有限公司 Optical fiber gyroscope for improving velocity sensitivity
CN104075704A (en) * 2014-06-26 2014-10-01 中航捷锐(北京)光电技术有限公司 Digital closed loop optical fiber gyroscope with double-interferometer system
CN104236537A (en) * 2014-09-12 2014-12-24 北京航空航天大学 Light source intensity noise suppression digital double closed-loop method based on intensity modulator
CN104236537B (en) * 2014-09-12 2017-08-11 北京航空航天大学 Light source intensity noise based on intensity modulator suppresses digital double closed-loop method
CN104613985A (en) * 2015-02-12 2015-05-13 重庆华渝电气集团有限公司 Method for improving interchangeability of fiber-optic gyroscope in navigation system
CN104613985B (en) * 2015-02-12 2017-09-29 重庆华渝电气集团有限公司 The method for improving optical fibre gyro interchangeability in navigation system
CN108387787A (en) * 2018-01-16 2018-08-10 清华大学 A kind of integrated common path interference electric field measurement system for eliminating polarization correlated noise

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