CN105547336A - Fiber grating sensing demodulation device and method on the basis of photoelectric oscillation loop - Google Patents
Fiber grating sensing demodulation device and method on the basis of photoelectric oscillation loop Download PDFInfo
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- CN105547336A CN105547336A CN201510870825.3A CN201510870825A CN105547336A CN 105547336 A CN105547336 A CN 105547336A CN 201510870825 A CN201510870825 A CN 201510870825A CN 105547336 A CN105547336 A CN 105547336A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/268—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light using optical fibres
Abstract
The present invention discloses a fiber grating sensing demodulation device and method on the basis of a photoelectric oscillation loop. The device provided by the invention comprises a photoelectric oscillation loop which is formed by connecting an electrooptical modulator, a first three-port optical circulator, a fiber-optic amplifier, a photoelectric detector, a radio-frequency amplifier, a radio-frequency filter and a 3dB three-port radio frequency power divider in order; a broadband light source is connected with the input port of a second three-port optical circulator; the output port of the second three-port optical circulator is connected with the input port of the electrooptical modulator; the second port of the second three-port optical circulator is connected with a sensing Prague fiber grating; the second port of the first three-port optical circulator is connected with a chirp Prague fiber grating; and one output port of the 3dB three-port radio frequency power divider is connected with the electric drive port of the electrooptical modulator, and the other output port of the 3dB three-port radio frequency power divider is connected with a radio frequency meter. The novel fiber grating sensing demodulation method through adoption of the microwave photonic technology provided by the invention is suitable for the application of low-cost and high-precision fiber grating demodulation.
Description
Technical field
The present invention relates to microwave photon technology, photoelectron technology and optical fiber sensing technology, belong to the technical field adopting microwave photon technology to carry out optical fiber grating sensing and demodulation.
Background technology
Fiber-optic grating sensor have volume little, lightweight, be easy to realize the remote and characteristic such as distributed measurement and anti-electromagnetic interference (EMI), be therefore widely used in the telemeasurement field of temperature, stress and refractive index.
Traditional fiber grating demodulation method often adopts optical filter demodulation method, such as tunable F-P filter method, non-equilibrium M-Z fibre optic interferometer method and grating matching method etc.These methods or higher to the performance requirement of optical filter, cost is higher; Or need more optical filter, the higher and complex structure of cost, more difficult practical.Therefore, develop fast demodulation and go out the method for optic fiber grating wavelength variable quantity and low-cost equipment has great importance.
Summary of the invention
The object of the invention is to the deficiency for existing Optical Demodulation technology, optoelectronic oscillation loop is utilized sensing bragg grating to be converted to the frequency shift amount of radiofrequency signal with the wavelength variable quantity of extraneous sensing parameter, a kind of novel fiber grating sensing demodulation method is provided, thus realize the optic fiber grating wavelength demodulation of low-cost and high-precision, provide the device realizing the method simultaneously.
For achieving the above object, the present invention is by the following technical solutions:
Based on the fiber grating sensing demodulation device of optoelectronic oscillation loop, comprise by electrooptic modulator, one or three port photocirculator, fiber amplifier, photodetector, radio frequency amplifier, radio-frequency filter and 3dB tri-port RF Power Splitter be the connected optoelectronic oscillation loop formed successively, wideband light source is connected with the input port of the two or three port photocirculator, the output port of described two or three port photocirculator is connected with the input port of described electrooptic modulator, second port of described two or three port photocirculator is connected with a sensing bragg grating, second port of described one or three port photocirculator is connected with a chirped fiber Bragg gratings, one output port of described 3dB tri-port RF Power Splitter is connected with the electric drive port of described electrooptic modulator, another output port of described 3dB tri-port RF Power Splitter is connected with a rf frequency meter.
Adopt the above-mentioned fiber grating sensing demodulation device based on optoelectronic oscillation loop to carry out the method for fiber grating demodulation, comprise the following steps:
1) light that described wideband light source is launched arrives described sensing bragg grating through described two or three port photocirculator, light through the reflection of sensing bragg grating arrives described electrooptic modulator through the two or three port photocirculator again, the light signal exported by electrooptic modulator arrives chirped fiber Bragg gratings reflection through the input port of the one or three port photocirculator, after the output port of the one or three port photocirculator arrives the amplification of described fiber amplifier, enter described photodetector and carry out opto-electronic conversion, the electric signal obtained is by the amplification of radio frequency amplifier, the filtering of radio-frequency filter, the electric drive port of electrooptic modulator is arrived through 3dB tri-port RF Power Splitter, electro-optic conversion is carried out by electrooptic modulator, form optoelectronic oscillation loop and so forth, the radiofrequency signal obtaining certain frequency at the output port of 3dB tri-port RF Power Splitter exports, its frequency is
f＝kc/nL(1)
Wherein n is optical fibre refractivity, and c is the light velocity in vacuum, and L is optoelectronic oscillation loop-length, and k is integer, and k value size is determined by radio-frequency filter frequency size, exports radio frequency signal frequency and is determined by radio-frequency filter frequency; Radio-frequency filter bandwidth is less than the free spectral range f=c/nL of vibration harmonic wave on the one hand, determines the measurement range of this sensing demodulating system on the other hand;
2) when extraneous sensing parameter change, the reflection peak wavelength of sensing bragg grating described in optoelectronic oscillation loop can change thereupon, its knots modification is Δ λ, then the reflection position of its correspondence in described chirped fiber Bragg gratings can change, its variable quantity can be expressed as Δ z=Δ λ/D, wherein D is the chirp rate of chirped fiber Bragg gratings, now, exports radio frequency signal frequency and is changed to
f'＝kc/n(L+Δz)(2)
3) rf frequency measurement amount output signal frequency is adopted, then can according to (1) (2) two formula obtain the changes delta z of light at chirped fiber Bragg gratings reflection position, then obtained the wavelength variable quantity of sensing bragg grating by Δ λ=Δ z/D, thus demodulation is carried out to sensing parameter.
After adopting technique scheme, the present invention is compared with background technology, and tool has the following advantages:
Present invention utilizes the dispersion characteristics of optoelectronic oscillation frequency loop characteristic and chirped fiber grating, radio frequency signal frequency knots modification is exported because sensing cloth glug optic fiber grating wavelength changes the optoelectronic oscillation loop caused by measuring, carry out bragg grating sensing and demodulation, the present invention is relative to other traditional measurement schemes, possess roomy, the anti-electromagnetic interference (EMI) of band, be suitable for the outstanding advantages such as high precision, low cost and miniaturization, greatly reduce cost and the complexity of measurement.The present invention is a kind of sensing and demodulating Bragg fiber grating method that novel employing microwave photon technology realizes, and is very suitable for low-cost and high-precision sensing and demodulating.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention;
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
Embodiment as shown in Figure 1, based on a fiber grating sensing demodulation device for optoelectronic oscillation loop, it comprises wideband light source the 1, the 23 port photocirculator 2, sensing bragg grating 3, electrooptic modulator the 4, the 1 port photocirculator 5, chirped fiber Bragg gratings 6, fiber amplifier 7, photodetector 8, radio frequency amplifier 9, radio-frequency filter 10,3dB tri-port RF Power Splitter 11 and rf frequency meter 12.
The connection of above all parts is as follows, wideband light source 1 is connected with the input port of the two or three port photocirculator 2, the output port of the two or three port photocirculator 2 is connected with the input port light of electrooptic modulator 4, second port of the two or three port photocirculator 2 is connected with one end of sensing bragg grating 3, the output port of electrooptic modulator 4 is connected with the input port light of the one or three port photocirculator 5, the output port of the one or three port photocirculator 5 is connected with the input port of fiber amplifier 7, second port of the one or three port photocirculator 5 is connected with chirped fiber Bragg gratings 6, the output port of fiber amplifier 7 is connected with the input port light of photodetector 8, the output port of photodetector 8 is electrically connected with the input port of radio frequency amplifier 9, the output port of radio frequency amplifier 9 is connected with the input port of radio-frequency filter 10, the output port of radio-frequency filter 10 is connected with the input port of 3dB tri-port RF Power Splitter 11, an output port of 3dB tri-port RF Power Splitter 11 is connected with the electric drive port of electrooptic modulator 4, the another one output port of 3dB tri-port RF Power Splitter 11 is connected with rf frequency meter 12.Electrooptic modulator the 4, the 1 port photocirculator 5, fiber amplifier 7, photodetector 8, radio frequency amplifier 9, radio-frequency filter 10 and the 3dB tri-port RF Power Splitter 11 that are wherein connected successively form optoelectronic oscillation loop.
Above-mentioned fiber grating sensing demodulation device is adopted to comprise the following steps to the method for carrying out sensing and demodulating:
1) light that wideband light source 1 is launched arrives sensing bragg grating 3 through the two or three port photocirculator 2, and reflect through sensing bragg grating 3, electrooptic modulator 4 is arrived again by the two or three port photocirculator 2, the light signal exported by electrooptic modulator 4 is after the input port arrival chirped fiber Bragg gratings 6 of the one or three port photocirculator 5 reflects, output port through the one or three port photocirculator 5 arrives fiber amplifier 7 and amplifies, enter photodetector 8 and carry out opto-electronic conversion, the electric signal obtained is by the amplification of radio frequency amplifier 9, the filtering of radio-frequency filter 10, the electric drive port of electrooptic modulator 4 is arrived through 3dB tri-port RF Power Splitter 11, electro-optic conversion is carried out by electrooptic modulator 4, form optoelectronic oscillation loop and so forth, the radiofrequency signal obtaining certain frequency at the output port of 3dB tri-port RF Power Splitter 11 exports, its frequency is
f＝kc/nL(1)
Wherein n is optical fibre refractivity, and c is the light velocity in vacuum, and L is optoelectronic oscillation loop-length, and k is integer.K value size is determined by radio-frequency filter 10 frequency size, exports radio frequency signal frequency simultaneously and is determined by radio-frequency filter 10 frequency; The bandwidth of radio-frequency filter 10 is less than the free spectral range f=c/nL of vibration harmonic wave on the one hand, which determines the measurement range of this sensing demodulating system on the other hand.
2) when extraneous sensing parameter change, in optoelectronic oscillation loop, the reflection peak wavelength of sensing bragg grating 3 can change thereupon, its knots modification is Δ λ, then the reflection position of its correspondence in chirped fiber Bragg gratings 6 can change, its variable quantity can be expressed as Δ z=Δ λ/D, and wherein D is the chirp rate of chirped fiber Bragg gratings 6.Now, export radio frequency signal frequency to be changed to
f'＝kc/n(L+Δz)(2)
3) adopt rf frequency meter 12 to measure and export radio frequency signal frequency, then can according to (1) (2) two formula obtain the changes delta z of light at chirped fiber Bragg gratings 6 reflection position, then obtained the wavelength variable quantity of sensing bragg grating 3 by Δ λ=Δ z/D, thus demodulation is carried out to sensing parameter.
Present invention employs optoelectronic oscillation loop, the light reflected by sensing bragg grating 3 is as the light source of optoelectronic oscillation loop, and chirped fiber Bragg gratings 6 is set in optoelectronic oscillation loop time delay is provided, when extraneous sensing parameter change, cause the change of the reflection wavelength of sensing bragg grating 3, thus make the reflection position change of this light signal in chirped fiber Bragg gratings 6.Sensing bragg grating 3 reflection wavelength is positioned at the broadband reflection band of chirped fiber Bragg gratings 6.Therefore the light path of optoelectronic oscillation loop can change, thus causes the change of the radio frequency output signal frequency of optoelectronic oscillation loop.Measured by rf frequency meter 11 and export radio frequency signal frequency change, obtain the changed wavelength of sensing bragg grating, thus realize the demodulation to sensing parameter.
The above; be only the present invention's preferably embodiment, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claim.
Claims (2)
1. based on the fiber grating sensing demodulation device of optoelectronic oscillation loop, it is characterized in that: comprise by electrooptic modulator, one or three port photocirculator, fiber amplifier, photodetector, radio frequency amplifier, radio-frequency filter and 3dB tri-port RF Power Splitter be the connected optoelectronic oscillation loop formed successively, wideband light source is connected with the input port of the two or three port photocirculator, the output port of described two or three port photocirculator is connected with the input port of described electrooptic modulator, second port of described two or three port photocirculator is connected with a sensing bragg grating, second port of described one or three port photocirculator is connected with a chirped fiber Bragg gratings, one output port of described 3dB tri-port RF Power Splitter is connected with the electric drive port of described electrooptic modulator, another output port of described 3dB tri-port RF Power Splitter is connected with a rf frequency meter.
2. adopt the fiber grating sensing demodulation device based on optoelectronic oscillation loop according to claim 1 to carry out the method for fiber grating demodulation, it is characterized in that: comprise the following steps
1) light that described wideband light source is launched arrives described sensing bragg grating through described two or three port photocirculator, light through the reflection of sensing bragg grating arrives described electrooptic modulator through the two or three port photocirculator again, the light signal exported by electrooptic modulator arrives chirped fiber Bragg gratings reflection through the input port of the one or three port photocirculator, after the output port of the one or three port photocirculator arrives the amplification of described fiber amplifier, enter described photodetector and carry out opto-electronic conversion, the electric signal obtained is by the amplification of radio frequency amplifier, the filtering of radio-frequency filter, the electric drive port of electrooptic modulator is arrived through 3dB tri-port RF Power Splitter, electro-optic conversion is carried out by electrooptic modulator, form optoelectronic oscillation loop and so forth, the radiofrequency signal obtaining certain frequency at the output port of 3dB tri-port RF Power Splitter exports, its frequency is
f＝kc/nL(1)
Wherein n is optical fibre refractivity, and c is the light velocity in vacuum, and L is optoelectronic oscillation loop-length, and k is integer, and k value size is determined by radio-frequency filter frequency size, exports radio frequency signal frequency simultaneously and is determined by radio-frequency filter frequency; Radio-frequency filter bandwidth is less than the free spectral range f=c/nL of vibration harmonic wave on the one hand, determines the measurement range of this sensing demodulating system on the other hand;
2) when extraneous sensing parameter change, the reflection peak wavelength of sensing bragg grating described in optoelectronic oscillation loop can change thereupon, its knots modification is Δ λ, then the reflection position of its correspondence in described chirped fiber Bragg gratings can change, its variable quantity can be expressed as Δ z=Δ λ/D, wherein D is the chirp rate of chirped fiber Bragg gratings, now, exports radio frequency signal frequency and is changed to
f'＝kc/n(L+Δz)(2)
3) rf frequency measurement amount output signal frequency is adopted, then can according to (1) (2) two formula obtain the changes delta z of light at chirped fiber Bragg gratings reflection position, then obtained the wavelength variable quantity of sensing bragg grating by Δ λ=Δ z/D, thus demodulation is carried out to sensing parameter.
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| CN108400516A (en) * | 2018-05-04 | 2018-08-14 | 北京交通大学 | A kind of optical-electronic oscillator stress sensing system based on Nonlinear Dispersive element |
| CN108879295A (en) * | 2018-08-06 | 2018-11-23 | 北京无线电计量测试研究所 | A kind of high stability optical-electronic oscillator and control method |
| CN108955939A (en) * | 2018-07-19 | 2018-12-07 | 南京航空航天大学 | A kind of fiber grating temperature sensor demodulating system |
| CN108981762A (en) * | 2018-06-19 | 2018-12-11 | 广东工业大学 | Thermostabilization sensing demodulating system and method are carried out using the double phase-shifted fiber gratings in narrowband |
| CN109520533A (en) * | 2019-01-23 | 2019-03-26 | 国网江西省电力有限公司信息通信分公司 | Fiber grating demodulation device and method based on fiber optic loop microwave photon filter |
| CN112683313A (en) * | 2020-12-15 | 2021-04-20 | 南京信息职业技术学院 | Sensor array device of multi-photoelectric oscillator and measuring method |
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