CN206399453U - A kind of signal receiving device and phase-shifted fiber grating demodulating system - Google Patents
A kind of signal receiving device and phase-shifted fiber grating demodulating system Download PDFInfo
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- CN206399453U CN206399453U CN201621392340.4U CN201621392340U CN206399453U CN 206399453 U CN206399453 U CN 206399453U CN 201621392340 U CN201621392340 U CN 201621392340U CN 206399453 U CN206399453 U CN 206399453U
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Abstract
The utility model discloses a kind of signal receiving device and phase-shifted fiber grating demodulating system, multiple spot can not be carried out while the problem of sensing to solve existing phase-shifted fiber grating sensor-based system, realize that demodulation accuracy is high, multiple phase-shifted fiber gratings can be multiplexed, and measurement range is big.The system includes frequency swept laser, coupler, first annular device, the second circulator, phase-shifted fiber grating array, gas absorption chamber, optical fiber FP interferometers, photodetector group, data acquisition device and demodulation module.
Description
Technical field
The utility model is related to fibre optical sensor field, more particularly to a kind of signal receiving device and phase-shifted fiber grating
Demodulating system.
Background technology
Fiber Bragg Grating FBG is as a kind of new sensor, because its unique advantage has more and more been closed
Note, application field is also increasingly extensive.Compared to traditional electricity, optical sensor, the transducing signal of fiber grating is compiled for wavelength
Code is without by electromagnetic interference, sensitivity is high and is easy to multiplexing.When it is influenceed by physical quantitys such as ambient temperature, pressure,
Its centre wavelength can change, therefore the sensor based on fiber grating can be used for the change of measurement external physical quantity.Optical fiber
Grating sensing system has the advantages that corrosion-resistant, stable chemical performance, small volume, lightweight, can be widely applied to measurement temperature,
The physical quantitys such as pressure, strain, acceleration, have been obtained extensively in fields such as civil structure, Aero-Space, petrochemical industry and medical science at present
General application.
Traditional fiber grating sensor reflection bandwidth is 0.2nm-0.5nm, and its temperature and the demodulation accuracy highest strained can
Reach 0.1 DEG C and 1 microstrain.And sensory field is increasingly increasing the demand of high-precision sensor, the demodulation of fiber grating
Precision is limited to its reflection bandwidth, reduces reflection bandwidth and is conducive to improving wavelength resolution.Phase-shifted fiber grating is as a kind of new
The fiber grating of type, the arrowband transmission peaks that it has enable it to be used for high-precision sensing field, such as ultrasonic sensing, weak signal
Detection etc..Phase-shifted fiber grating is a kind of non-homogeneous periodic optical grating, and index distribution is discontinuous.The grating is in conventional fiber cloth
The a certain privileged site of glug grating introduces π phase shift, produces the grating of 2 mutual out-phase.The grating class of this 2 mutual out-phase
It is similar to wavelength selective resonance chamber, it is allowed to which the light of resonance wavelength is injected into stopband, the extremely narrow transmission of a line width is opened in stopband
Window, the 3-dB bandwidth of the window is about 10pm, and its bandwidth reduces a number compared with the reflection bandwidth of ordinary optic fibre grating
Magnitude, and the centre wavelength and external world's strain, temperature of arrowband transmission peaks are linear, therefore it is suitable for high-precision sensing.
Edge filter method is used phase-shifted fiber grating traditional demodulation scheme more, although the demodulation scheme sensitivity is high,
Easily influence by environment temperature, it is necessary to the centre wavelength for adjusting light source in real time realizes optimum sensitivity, to add system complex
Degree.The measurement range of the other program is small, can only cover the size of transmission bandwidth, about 10pm scope.It is limited to manufacture craft,
The centre wavelength of each phase-shifted fiber grating can not accomplish the uniformity of pm magnitudes, so each sensing point is required to be equipped with one
Narrow-linewidth laser light source, it is impossible to carry out multiple spot using a set of light-source system and sense simultaneously.
The content of the invention
In order to overcome the defect of prior art, the technical problems to be solved in the utility model is to provide a kind of signal and receives dress
Put and phase-shifted fiber grating demodulating system, can not carry out multiple spot solving existing phase-shifted fiber grating sensor-based system senses simultaneously
The problem of, realize that demodulation accuracy is high, multiple phase-shifted fiber gratings can be multiplexed, and measurement range is big.
In order to solve the above technical problems, a kind of signal receiving device in the utility model, including frequency swept laser, coupling
Device, first annular device, the second circulator, phase-shifted fiber grating array, gas absorption chamber, optical fiber FP interferometers, photodetector
Group and data acquisition module；
The sweep light of the frequency swept laser output is divided into the first via, the second road and the 3rd tunnel after the coupler and swept
Frequency light；The first via sweep light is incided after the phase-shifted fiber grating array by the first annular device, and passes through institute
State first annular device output phase shift fiber grating sensing signal；Second tunnel sweep light is incided after the gas absorption chamber,
The transmission signal of output gas absorption chamber；The 3rd tunnel sweep light incides the optical fiber FP by second circulator to be done
After interferometer, and pass through the second circulator output optical fibre FP interferometer reflection signals；The phase-shifted fiber grating transducing signal,
The transmission signal of the gas absorption chamber and the optical fiber FP interferometer reflections signal are after the photodetector group, respectively
It is converted into after correspondence analog signal, collection of simulant signal is completed by the data acquisition module.
Alternatively, the instantaneous line width of the frequency swept laser is less than 10pm magnitudes.
Alternatively, phase-shifted fiber grating array is connected in same optical fiber by least two phase-shifted fiber grating.
Specifically, phase-shifted fiber grating array is constituted by being connected at least two phase-shifted fiber grating in same optical fiber.
Specifically, the phase-shifted fiber grating array carries out port number extension by space division multiplexing.
Alternatively, the photodetector group includes the first photodetector, the second photodetector and the spy of the 3rd photoelectricity
Survey device.
Alternatively, the 3rd tunnel sweep light incides the optical fiber FP interferometers by second circulator, passes through
The optical fiber FP interferometers are carried out etc. after wave number subdivision, and the wave number interval reflection peak such as have by second circulator output
Optical fiber FP interferometer reflection signals.
In order to solve the above technical problems, a kind of phase-shifted fiber grating demodulating system in the utility model, including such as take up an official post
Meaning one signal receiving device and demodulation module.
The utility model has the beneficial effect that：
The utility model, which effectively solves existing phase-shifted fiber grating sensor-based system, can not carry out multiple spot while the problem of sensing,
Realize that demodulation accuracy is high, multiple phase-shifted fiber gratings can be multiplexed, and measurement range is big.
Brief description of the drawings
Fig. 1 is a kind of structural representation of signal receiving subsystem in the utility model embodiment；
Fig. 2 is demodulating algorithm principle flow chart in the utility model embodiment；
Fig. 3 is time-domain signal schematic diagram on three detectors in the utility model embodiment.
Embodiment
In order to solve problem of the prior art, the utility model provides a kind of signal receiving subsystem.The utility model
The non-linear jittering noise for the swept light source that the signal receiving subsystem of proposition is used and the arrowband transmission peaks of phase-shifted fiber grating
Bandwidth is in 10pm magnitudes, if using traditional gamma correction scheme, the error introduced is larger, it is therefore desirable to carry out high
The gamma correction of precision.Come school using the combined type absolute wavelength reference based on optical fiber FP interferometers and gas absorption chamber for this
It is non-linear in quasi wave long scan, nonlinear calibration precision is improved to pm magnitudes, and can will be multiple by wavelength-division, time division multiplexing
Phase shift optical fiber multiplexing carries out multiple spot high-precision large-range sensing on an optical fiber.Below in conjunction with accompanying drawing and embodiment, to this
Utility model is further elaborated.It should be appreciated that specific embodiment described herein is only to explain that this practicality is new
Type, does not limit the utility model.
As shown in figure 1, the utility model embodiment provides a kind of phase-shifted fiber grating demodulating system, including frequency swept laser
1st, 1x3 couplers 2, first annular device 3, the second circulator 8, phase-shifted fiber grating array 4, gas absorption chamber 6, optical fiber FP interference
Instrument 9, photodetector group (including photoelectric sensor 5,7 and 10) and data acquisition module 11；
The sweep light that the frequency swept laser 1 is exported is divided into the first via, the second road and the 3rd tunnel after the coupler 2
Sweep light；The first via sweep light is incided after the phase-shifted fiber grating array 4 by the first annular device 3, and is led to
Cross the output phase shift fiber grating sensing signal of first annular device 3；Second tunnel sweep light incides the gas and absorbed
Behind room 6, the transmission signal of output gas absorption chamber；The 3rd tunnel sweep light is incided described by second circulator 8
After optical fiber FP interferometers 9, and pass through the output optical fibre FP interferometer reflection signals of the second circulator 8；The phase shift optical fiber light
Grid transducing signal, the transmission signal of the gas absorption chamber and the optical fiber FP interferometer reflections signal pass through the photodetection
After device group, it is converted into respectively after correspondence analog signal, collection of simulant signal is completed by the data acquisition module 11.
On the basis of above-described embodiment, it is further proposed that the variant embodiment of above-described embodiment, needs explanation herein
It is, in order that description is brief, the only description and the difference of above-described embodiment in each variant embodiment.
In one embodiment of the present utility model, the instantaneous line width of the frequency swept laser is less than 10pm magnitudes.Phase shift
Optical fiber optical grating array is connected in same optical fiber by least two phase-shifted fiber grating.
Furtherly, at least two phase-shifted fiber grating is connected in same optical fiber by wavelength-division and time-sharing multiplex.
Further say, the phase-shifted fiber grating array carries out port number extension by space division multiplexing.
The photodetector group includes the first photodetector 5, the second photodetector 7 and the 3rd photodetector
10。
The utility model, which effectively solves existing phase-shifted fiber grating sensor-based system, can not carry out multiple spot while the problem of sensing,
Realize that demodulation accuracy is high, multiple phase-shifted fiber gratings can be multiplexed, and measurement range is big.
Specifically, the utility model has used narrow linewidth frequency swept laser 1, and the instantaneous line width of the laser is less than 10pm amounts
Level, can collect the arrowband transmission peak-to-peak signal in phase-shifted fiber grating reflectance spectrum in time domain.
Multiple phase-shifted fiber gratings can be connected in same optical fiber by wavelength-division, time division multiplexing, and can further be passed through
Space division multiplexing carries out port number extension, improves the sensing point quantity of system.
Gas absorption chamber 6 and optical fiber FP interferometers 9 have been used collectively as wavelength reference simultaneously.Gas absorption chamber is as exhausted
To standard of wavelength, and optical fiber FP interferometers 9 then as etc. wave number interval multiple wavelengths filter, the two may be constructed with absolute ripple
The wavelength chi of long mark.Furtherly, optical fiber FP interferometers 9 such as can carry out at the wave number subdivision, interferometer reflection spectrum to frequency sweep spectrum
In frequency sweep track between each peak can be approximately linear scan so that effectively non-linear during calibration frequency sweep, improve wavelength
The accuracy of demodulation.
In another embodiment of the present utility model, the 3rd tunnel sweep light is incided by second circulator
The optical fiber FP interferometers, after the wave number subdivision such as optical fiber FP interferometers progress, and it is defeated by second circulator
Go out have etc. wave number interval reflection peak optical fiber FP interferometer reflection signals.
Furtherly, demodulation module is increased on the signal receiving device, you can constitute phase-shifted fiber grating demodulation system
System.
Conciliate that is, the phase-shifted fiber grating demodulating system includes as above signal receiving device described in any one
Mode transfer block.
Wherein, the demodulation module is used to be demodulated the analog signal of collection.Wherein, demodulation module 12 is specially to locate
Manage device.
Specifically, the relative position that demodulation module composes each peak according to gas absorption spectrum line and optical fiber FP interferometer reflections is closed
System, determines that optical fiber FP interferometer reflections compose the absolute wavelength at each peak.Then the narrow of phase-shifted fiber grating is found by peak-seeking algorithm
Time-domain position with transmission peaks, the reflection peak of adjacent optical fiber FP interferometers is found in this position both sides, and then by linearly inserting
Value-based algorithm calculates the centre wavelength of phase-shifted fiber grating arrowband transmission peaks, realizes a wide range of while multiple phase-shifted fiber gratings
High accuracy demodulation.
Illustrate.
As shown in figure 1, narrow linewidth frequency swept laser 1 is a light source with output tail optical fiber, its output light is through overcoupling
Device 2 is divided into three beams, and the first beam reaches phase-shifted fiber grating array 4 by circulator 3 and (is illustrated as 2 phase-shifted fiber grating strings
Connection), its reflected light is received by the 3rd port of circulator by photodetector 5；Second beam light of coupler output passes through
Gas absorption chamber 6, its transmitted light is received by photodetector 7；The three-beam of coupler passes through circulator 8, reaches optical fiber FP
Interferometer 9, three port of its interference signal through circulator is received by photodetector 10.Due to narrow linewidth frequency swept laser
Its output center wavelength is with time periodically continued change, therefore reflection or transmitted spectrum signal can be converted into time domain light intensity letter
Number, received by three photodetectors, be converted into after analog electrical signal entering the solution based on data collecting card 11 and processor 12
Mode transfer block.
In reference signal, the absorption line of gas absorption chamber can as absolute wavelength standard, optical fiber FP interferometers because
The particular design of its chamber length can obtain the interference fringe that FSR is 50pm magnitudes, can be with shape with reference to the absorption line of gas absorption chamber
Into lambad labeling etc. wave number interval wavelength chi, the centre wavelength of the arrowband transmission peaks of phase-shifted fiber grating can be carried out high
Precision measure.The method of measurement is linear interpolation method, can measure phase shift light by measuring the relative position of arrowband transmission peaks
The change of fine raster center wavelength, realizes the sensing and demodulating of physical quantity to external world.
The flow chart of demodulating algorithm of the present utility model is as shown in Fig. 2 gather three after synchronization using data collecting card
Analog signal on photodetector, using the collection signal of a complete cycle as process object, first by analog electrical signal
Digital-to-analogue conversion and digital filtering are carried out, by setting suitable peak-seeking threshold value and peak width to determine phase-shifted fiber grating arrowband transmission peaks
Position.As shown in figure 3,1. signal is phase-shifted fiber grating transducing signal, 2. signal is optical fiber FP interferometer reflection peak-to-peak signals,
3. signal is the transmission signal of gas absorption chamber.By the transmission peaks of gas absorption chamber, its line width is narrower, about 10pm magnitudes, and
The FSR of optical fiber FP interferometers is about 50pm, and it is then a definite value to be converted into frequency values, therefore can pass through the exhausted of gas absorption spectrum line
The absolute wavelength at each interferometer reflection peak can be oriented to the FSR value of wavelength and interferometer, thus above-mentioned two reference signal
Just the wavelength chi at the wave number interval such as one is constituted.
By taking wherein some sensing phase-shifted fiber grating as an example, if meta is set to t at that timesensOr, can be looked for by peak-seeking algorithm
The position t at the interferometer reflection peak of its adjacent both sides on to time domainref1And tref2, its corresponding wavelength is respectively λref1And λref2。
Sensing phase-shifted fiber grating centre wavelength can be solved by interpolation algorithmAnd this
The change of centre wavelength and external physical quantity can realize the sensing of physical quantity to external world in one-to-one relationship.
In the utility model：
1. the multiplexing of multiple phase-shift fiber grating.Multiple phase-shifted fiber gratings can be connected on same by wavelength-division, time division multiplexing
In root optical fiber, and port number extension further can be carried out by space division multiplexing, improve the sensing point quantity of system.
2. it is big to demodulate scope.I.e. dynamic range is big, and the scope of conventional method demodulation is saturating no more than phase-shifted fiber grating arrowband
The 3-dB bandwidth at peak, about 10pm are penetrated, and the demodulation rule is not limited, can carry out wide range sensing, it, which demodulates scope, is
Determined by swept bandwidth and grating multiplexing quantity.
3. high accuracy.Gamma correction method has been used, using the optical fiber FP interferometers that can be finely divided to swept frequency range (certainly
It is 50pm magnitudes by spectrum journey), make frequency sweep is non-linear to be calibrated, and high-precision absolute wavelength is obtained by gas absorption chamber
Demodulation.
Although This application describes particular example of the present utility model, those skilled in the art can not depart from this reality
With designing modification of the present utility model on the basis of new concept.
Those skilled in the art are not departing from the base of the utility model content under the inspiration of the utility model technical concept
On plinth, various improvement can also be made to of the present utility model, this still falls within protection domain of the present utility model.
Claims (8)
1. a kind of signal receiving device, it is characterised in that described device includes frequency swept laser, coupler, first annular device, the
Second ring device, phase-shifted fiber grating array, gas absorption chamber, optical fiber FP interferometers, photodetector group and data acquisition module；
The sweep light of the frequency swept laser output is divided into the first via, the second road and the 3rd tunnel frequency sweep after the coupler
Light；The first via sweep light is incided after the phase-shifted fiber grating array by the first annular device, and by described
First annular device output phase shift fiber grating sensing signal；Second tunnel sweep light is incided after the gas absorption chamber, defeated
Go out the transmission signal of gas absorption chamber；The 3rd tunnel sweep light incides the optical fiber FP by second circulator interferes
After instrument, and pass through the second circulator output optical fibre FP interferometer reflection signals；The phase-shifted fiber grating transducing signal, institute
The transmission signal and the optical fiber FP interferometer reflections signal of gas absorption chamber are stated after the photodetector group, is turned respectively
Change into after correspondence analog signal, collection of simulant signal is completed by the data acquisition module.
2. device as claimed in claim 1, it is characterised in that the instantaneous line width of the frequency swept laser is less than 10pm magnitudes.
3. device as claimed in claim 1, it is characterised in that phase-shifted fiber grating array is by being connected in same optical fiber extremely
Few 2 phase-shifted fiber gratings composition.
4. device as claimed in claim 3, it is characterised in that at least two phase-shifted fiber grating passes through wavelength-division and timesharing
Multiplexing is connected in same optical fiber.
5. device as claimed in claim 4, it is characterised in that the phase-shifted fiber grating array is led to by space division multiplexing
Road number extension.
6. device as claimed in claim 1, it is characterised in that the photodetector group includes the first photodetector, the
Two photodetectors and the 3rd photodetector.
7. the device as described in any one in claim 1-5, it is characterised in that the 3rd tunnel sweep light passes through described
Second ring device incides the optical fiber FP interferometers, after the wave number subdivision such as optical fiber FP interferometers progress, and passes through institute
State the second circulator output with etc. wave number interval reflection peak optical fiber FP interferometer reflection signals.
8. a kind of phase-shifted fiber grating demodulating system, it is characterised in that the phase-shifted fiber grating demodulating system includes such as right
It is required that signal receiving device described in any one and demodulation module in 1-7.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108204827A (en) * | 2016-12-16 | 2018-06-26 | 中国电子科技集团公司电子科学研究院 | A kind of phase-shifted fiber grating demodulating system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108204827A (en) * | 2016-12-16 | 2018-06-26 | 中国电子科技集团公司电子科学研究院 | A kind of phase-shifted fiber grating demodulating system |
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