CN209279996U - Multi-channel optical fibre current sensor based on wavelength-division multiplex - Google Patents
Multi-channel optical fibre current sensor based on wavelength-division multiplex Download PDFInfo
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- CN209279996U CN209279996U CN201822116209.0U CN201822116209U CN209279996U CN 209279996 U CN209279996 U CN 209279996U CN 201822116209 U CN201822116209 U CN 201822116209U CN 209279996 U CN209279996 U CN 209279996U
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Abstract
The utility model provides a kind of multi-channel optical fibre current sensor based on wavelength-division multiplex, and polarised light generating device exports m route polarised light, and each route polarised light enters a sensing branch；Light beam is reflected using reflection-type optical fiber grating in each sensing branch.The reflected light of each sensing branch output can interfere in polarised light generating device, be transmitted to optical fiber filter later.Optical fiber filter can be according to setting sequence by the corresponding interference light conduction of different sensing branches, the corresponding interference light intensity of different sensing branches is converted to electric signal by photodetector, it may be possible to which the electric signal detected according to photodetector is counter to release current value detected in corresponding sensing branch.Above scheme provided by the utility model makes same set of optical fiber filter connect multiple sensing branches with photodetector, to the electric current in precise measurement different measuring points, is greatly saved the economic cost of fibre optic current sensor based on wavelength-division multiplex technique.
Description
Technical field
The utility model relates to fiber-optic current sensor technical field more particularly to a kind of multi-channel optical fibres based on wavelength-division multiplex
Current sensor.
Background technique
Fibre optic current sensor is usually made of acquisition module and Fibre Optical Sensor ring, and an acquisition module can only connect
One Fibre Optical Sensor ring.Using the fibre optic current sensor of digital closed loop technology, eigenfrequency is up to hundreds of kHz, sample rate
Also it in kHz magnitude, and for certain applications occasion, generally requires to monitor multiple electric current measuring points, and compared to fiber-optic current sensor
The signal modulation frequency of device, current signal to be measured are equivalent to gradual amount or DC quantity, of less demanding to the response speed of measurement,
Even the sometimes requirement to output data refresh time, therefore can be excellent by the technology of fibre optic current sensor only in second-time
Gesture realizes the Configuration of Optical Fiber Current of multiplexing, and different Fibre Optical Sensor rings is connected using the same acquisition module, benefit
It is realized with multiplexing technique while formula measurement is scanned to multiple electric current measuring points.
Current existing multiplexing scheme includes space division multiplexing and time division multiplexing.The former is to be adopted by photoswitch by a set of
Collection module connects multiple Fibre Optical Sensor rings and has been attached to different electric current measuring points when photoswitch switches between different channels
On Fibre Optical Sensor ring, to realize multichannel measurement, since each Fibre Optical Sensor ring is there is intrinsic measurement error, because
This still needs to increase essential status monitoring member in multichannel measuring point in practice to guarantee the measuring precision
Part, such as temperature sensor, for carrying out online compensation to measurement error；The latter is to be adopted one by broadband optical fiber coupler
Collection module is connect with multiple Fibre Optical Sensor rings, and the different optical fiber of length is added in the input optical cable of each Fibre Optical Sensor ring and prolongs
Shi Huan, therefore different Fibre Optical Sensor rings return to the time difference of optical signal, can demodulate each sensing by time-multiplexed method
The current information returned in ring, this solution increases the demand costs to polarization maintaining optical fibre, with the increase of multiplex channel, sensing
The cost of device also will constantly rise, and similarly improve the scheme cost for needing that status monitoring is carried out to multichannel measuring point.
Utility model content
The utility model is intended to provide a kind of multi-channel optical fibre current sensor based on wavelength-division multiplex, to solve the prior art
It is middle to realize that the existing technology that structure is complicated, at high cost is asked when measuring to multiple current detecting points using multiplexing technique
Topic.
To solve the above problems, the utility model provides a kind of multi-channel optical fibre current sensor based on wavelength-division multiplex, packet
Include m sensing branch, polarised light generating device, optical fiber filter and photodetector:
The sensing branch includes fiber optic loop and the optical-fibre wave plate and reflection-type optical fiber light that the fiber optic loop both ends are arranged in
Grid；It is passed through inside the fiber optic loop by electrical conductor；Wherein, the reflection-type optical fiber grating in the different sensing branches is used
In the light beam of reflection different wave length；
The polarised light generating device exports m route polarised light, and a sensing is entered per the linearly polarized light described all the way
Branch；Each route polarised light includes the orthogonal two bunch polarised light in polarization direction；
In each sensing branch, the linearly polarized light is after the optical-fibre wave plate, the fiber optic loop by described anti-
It is obtained after the reflection of emitting fiber grating, the reflected light exports after the fiber optic loop and the optical-fibre wave plate；The reflected light
Wavelength it is corresponding with the reflection wavelength of the reflection-type optical fiber grating, the reflected light includes that polarization direction is mutually perpendicular to and has
Dephased two bunch polarised light, the phase difference are generated according to the electric current in the electrical conductor；
The linearly polarized light generating device receives the reflected light of each sensing branch output；It is each described anti-
The two bunch polarised lights penetrated in light interfere in the linearly polarized light generating device, and what is obtained after different reflecting interferences is dry
Light is related to corresponding to different wavelength；
The optical fiber filter is configured with multiple optical channels, and the gating wavelength of different optical channels corresponds to different sensing branches
Interference light；The optical fiber filter receives all interference lights of the linearly polarized light generating device output, according to setting sequence
Each optical channel output is sequentially turned on to the interference light of inductive sensing branch；
The photodetector detects the light intensity of the interference light of the optical fiber filter output, and obtains and the light intensity pair
The electric signal answered, the electric signal are used to obtain the current value of the electrical conductor in phase inductive sensing branch.
Optionally, anti-in any two sensings branch in the above-mentioned multi-channel optical fibre current sensor based on wavelength-division multiplex
The difference DELTA λ of the reflection wavelength of emitting fiber grating is all larger than Δ λmax；Wherein, Δ λmax=MAX [Δ λ1,Δλ2,……Δ
λm],ΔλiThe wave length shift range in temperature change of the reflection-type optical fiber grating in branch is sensed for i-th.
Optionally, in the above-mentioned multi-channel optical fibre current sensor based on wavelength-division multiplex, the polarised light generating device packet
It includes light source, optical transmission apparatus, be polarized and coupled apparatus, polarization-maintaining time delay optical fiber ring and beam splitter, in which:
The optical transmission apparatus, first input end are connect with the output end of the light source, the first output end with it is described
It is polarized and the connection of the first input end of coupled apparatus, the optical signal that the light source issues is transmitted to described through the optical transmission apparatus
It is polarized and coupled apparatus；
It is described to be polarized and the first output end of coupled apparatus is connect with the first input end of the polarization-maintaining time delay optical fiber ring, institute
The first output end for stating polarization-maintaining time delay optical fiber ring is connect with the first input end of the beam splitter；It is described be polarized and coupled apparatus will
The optical signal is converted to and is transmitted to institute through the polarization-maintaining time delay optical fiber ring after the orthogonal two bunch polarised light in polarization direction
State beam splitter；
For the beam splitter configured with second output terminal, m the first output ends and m the second input terminals, each of which is first defeated
Outlet is connect with the input terminal of a sensing branch, described in each of which second input terminal is connect with the output end of a sensing branch
The second output terminal of beam splitter is connect with the second input terminal of the polarization-maintaining time delay optical fiber ring；The beam splitter is by polarization direction phase
Mutually two vertical bunch polarised lights are divided into m route polarised light, obtain after the sensing branch instead per the linearly polarized light described all the way
It penetrates after light is back to the beam splitter and is exported through the polarization-maintaining time delay optical fiber ring；
It is described to be polarized and the second input terminal of coupled apparatus is connect with the second output terminal of the polarization-maintaining time delay optical fiber ring, it connects
Receive the reflected light of beam splitter output, reflected light it is described be polarized and coupler in interfere to obtain interference light after export；
Second input terminal of the optical transmission apparatus is polarized and the second output terminal of coupled apparatus is connect, the light with described
The second output terminal of transmission apparatus is connect with the input terminal of the optical fiber filter；The optical transmission apparatus receive described in be polarized and
It exports after the interference light of coupled apparatus output to the optical fiber filter.
Optionally, in the above-mentioned multi-channel optical fibre current sensor based on wavelength-division multiplex, the optical transmission apparatus is optical fiber
Circulator；Or,
The optical transmission apparatus includes fibre optic isolater and the fiber coupler that connect with the fibre optic isolater.
Optionally, in the above-mentioned multi-channel optical fibre current sensor based on wavelength-division multiplex, the beam splitter is broadband polarization-maintaining
Fiber coupler or polarization maintaining optical fibre wavelength division multiplexer.
Optionally, described to be polarized and coupled apparatus packet in the above-mentioned multi-channel optical fibre current sensor based on wavelength-division multiplex
Include optical fiber polarizer and straight waveguide phase modulator；The tail of the tail optical fiber of the optical fiber polarizer and the straight waveguide phase modulator
Fibre is using 45 ° to axis welding.
Optionally, described to be polarized and coupled apparatus packet in the above-mentioned multi-channel optical fibre current sensor based on wavelength-division multiplex
Include Y waveguide phase-modulator and polarization beam combiner；One branch's tail optical fiber of the Y waveguide phase-modulator and polarization beam combiner
One branch's tail optical fiber is using 90 ° to axis welding；Another branch's tail optical fiber of the Y waveguide phase-modulator and polarization beam combiner
Another branch's tail optical fiber is using 0 ° to axis welding.
The utility model provides a kind of multi-channel optical fibre current sensor based on wavelength-division multiplex, including m sensing branch, partially
Shake photogenerated device, optical fiber filter and photodetector.The polarised light generating device exports m route polarised light, per all the way
The linearly polarized light enters a sensing branch；Each route polarised light includes that orthogonal two bunch in polarization direction is inclined
Shake light.Light beam is reflected using reflection-type optical fiber grating in each sensing branch, therefore can guarantee that reflection obtains
The reflection wavelength of the corresponding reflection-type optical fiber grating of light beam is corresponding.The reflected light of each sensing branch output can be
It is interfered in polarised light generating device, is transmitted to optical fiber filter later.It can be according to setting sequence using optical fiber filter
Gate different optical channels, the optical signal of the corresponding wavelength of each optical channel, therefore can guarantee that optical fiber filter can be with
According to setting sequence by the corresponding interference light conduction of different sensing branches.Photodetector is according to same sequence by different sensings
The corresponding interference light intensity of branch is converted to electric signal.Since sensing branch, the optical channel of optical fiber filter and photodetector are defeated
Electric signal out has certain corresponding relationship, therefore counter can release corresponding biography according to the electric signal that photodetector detects
Feel current value detected in branch.Above scheme provided by the utility model is based on wavelength-division multiplex technique, makes same unjacketed optical fiber
Filter connects multiple sensing branches with photodetector and is greatly saved to the electric current in precise measurement different measuring points
The economic cost of fibre optic current sensor.
Detailed description of the invention
Fig. 1 is that the structure of the multi-channel optical fibre current sensor based on wavelength-division multiplex described in the utility model one embodiment is shown
It is intended to；
Fig. 2 is that the structure of the multi-channel optical fibre current sensor based on wavelength-division multiplex described in another embodiment of the utility model is shown
It is intended to；
Fig. 3 is that difference described in the utility model one embodiment senses reflection wavelength difference and optical fiber filter in branch
The relation schematic diagram of spatially selecting filtering band；
Fig. 4 is the fiber-optic current sensor based on the scanning of fiber F-P filter wavelength described in the utility model one embodiment
Device multiplexes schematic diagram；
Fig. 5 is the data acquisition principle figure based on fiber F-P filter described in the utility model one embodiment；
Fig. 6 is the modulating frequency table corresponding with scanning voltage of signal detection system described in the utility model one embodiment；
Fig. 7 is the time-sharing method principle signal of the modulation /demodulation of signal detection system described in the utility model one embodiment
Figure.
Specific embodiment
The utility model embodiment is further illustrated below in conjunction with attached drawing.It needs in the description of the present invention,
Bright is unless specifically defined or limited otherwise, term " installation ", " connected ", " connection " shall be understood in a broad sense, for example, can
To be to be fixedly connected, may be a detachable connection, or be integrally connected；It can be mechanical connection, be also possible to be electrically connected；It can
To be to be connected directly, the connection of two component internals can also be can be indirectly connected through an intermediary.For this field
For those of ordinary skill, the concrete meaning of above-mentioned term in the present invention can be understood with concrete condition.
Embodiment 1
The present embodiment provides a kind of multi-channel optical fibre current sensor based on wavelength-division multiplex passes as shown in Figure 1, including m
Feel branch 1, polarised light generating device 2, optical fiber filter 3 and photodetector 4.Wherein, the sensing branch 1 includes fiber optic loop
101 and the optical-fibre wave plate 102 and reflection-type optical fiber grating 103 at 101 both ends of fiber optic loop are set；In the fiber optic loop 101
Portion is passed through by electrical conductor 104；Wherein, the reflection-type optical fiber grating 103 in the different sensing branches 1 is for reflecting not
The light beam of co-wavelength；The polarised light generating device 2 exports m route polarised light, and an institute is entered per the linearly polarized light described all the way
State sensing branch 1；Each route polarised light includes the orthogonal two bunch polarised light in polarization direction；In each sensing branch
In road 1, the linearly polarized light is anti-by the reflection-type optical fiber grating 103 after the optical-fibre wave plate 101, the fiber optic loop 102
It is obtained after penetrating, the reflected light exports after the fiber optic loop 102 and the optical-fibre wave plate 101；The wavelength of the reflected light with
The reflection wavelength of the reflection-type optical fiber grating 103 is corresponding, and the reflected light includes that polarization direction is mutually perpendicular to and has phase
Two bunch polarised lights of potential difference, the phase difference are generated according to the electric current in the electrical conductor 104.
The linearly polarized light generating device 2 receives the reflected light that each sensing branch 1 exports；It is each described
Two bunch polarised lights in reflected light interfere in the linearly polarized light generating device 2, obtain after different reflecting interferences
Interference light correspond to different wavelength；The optical fiber filter 3 is configured with multiple optical channels, the gating wavelength of different optical channels
Interference light corresponding to different sensing branches 1；The optical fiber filter 3 receives the institute that the linearly polarized light generating device 2 exports
There is interference light, sequentially turns on each optical channel output to the interference light of inductive sensing branch 1 according to setting sequence；The photodetector
The light intensity for the interference light that the 4 detection optical fiber filters 3 export, and obtain electric signal corresponding with the light intensity, the telecommunications
Number for obtaining the current value of the electrical conductor 104 in phase inductive sensing branch 1.
In above scheme, the mutually orthogonal linearly polarized light in multichannel polarization direction is through respectively enteing in different sensing branches 1
Transmission, is reflected by the fiber grating 103 of sensor fibre end, and the sensing principle of each sensing branch 1 is identical, unique area
It is not that the reflection wavelength on different sensing branches 1 is different.By taking one of sensing branch 1 as an example, polarization direction is mutually orthogonal
Two bunch polarised lights become left-handed and right-circularly polarized light respectively at optical-fibre wave plate 101, into being transmitted in fiber optic loop 102,
The current induced magnetic field transmitted in electrical conductor 104 is based on Faraday magnetooptical effect, keeps this two beam circle in fiber optic loop 102 inclined
Phase difference, referred to as Faraday magneto-optical angle of phase displacement are produced between vibration light, the reflection-type optical fiber grating 103 through sensor fibre end is anti-
After penetrating, the polarization mode of two beam circularly polarized lights exchanges (i.e. left-handed rotation becomes right-handed rotation, and right-handed rotation becomes left-handed rotation), again by
Fiber optic loop 102, and Faraday effect is undergone to double the Faraday magneto-optical angle of phase displacement between two beam circularly polarized lights.This two beam circle is inclined
After light shake again by optical-fibre wave plate 101, linearly polarized light return is reverted to, and polarization mode exchanges.Two bunch returned are inclined
Vibration light enters linearly polarized light generating device 2 and interferes, modulation of the size of interference light intensity by Faraday magneto-optical angle of phase displacement,
Therefore the current information in electrical conductor 104 is carried in interference light signal, interference light signal enters optical fiber filter 3, optical fiber
Filter 3 can carry out spatially selecting filtering to the interference light signal in different wave length section, and the interference light signal being strobed reaches photoelectricity and visits
Electric signal is converted to after surveying device 4, electric signal demodulates the electric current in electrical conductor 104 after can be used for being acquired by signal processing circuit
Information.By gating the control of wavelength to optical fiber filter 3, the interference light returned on different sensing branches 1 can be successively scanned
Signal, to realize to the different measurements for sensing electric current in electrical conductor 104 in branches 1.
In above scheme, it is based on wavelength-division multiplex technique, making same set of optical device combination, (such as optical fiber filter 3, photoelectricity are visited
Survey device 4 etc.) it can connect multiple sensing branches 1, to the electric current in precise measurement different measuring points, it is greatly saved optical fiber electricity
The economic cost of flow sensor.Since this programme uses multiplexing structure, the engineering cost of single current measuring point can be with
Sensing branch can arbitrarily be increased and decreased when reducing with increasing for branch of multiplexing, and applying at the scene under the premise of light source bandwidth is enough
Normal work of the road without influencing other sensing branches.Moreover, because sensing optical path is designed using pure optical means, it is used
Optical device is passive device, will not be influenced by adverse circumstances such as external high voltage, high-intensity magnetic fields.
Embodiment 2
Multi-channel optical fibre current sensor provided in this embodiment based on wavelength-division multiplex, as shown in Fig. 2, therein described inclined
Vibration photogenerated device 2 includes light source 201, optical transmission apparatus 202, is polarized and coupled apparatus 203,204 and of polarization-maintaining time delay optical fiber ring
Beam splitter 205, wherein the optical transmission apparatus 202, first input end is connect with the output end of the light source 201, and first
Output end is polarized and the first input end of coupled apparatus 203 is connect with described, and the optical signal that the light source 201 issues is through the light
Transmission apparatus 202 is transmitted to described be polarized and coupled apparatus 203；It is described to be polarized and the first output end of coupled apparatus 203 and institute
State polarization-maintaining time delay optical fiber ring 204 first input end connection, the first output end of the polarization-maintaining time delay optical fiber ring 204 with described point
The first input end of beam device 205 connects；It is described be polarized and coupled apparatus 203 by the optical signal be converted to polarization direction mutually hang down
The beam splitter 205 is transmitted to through the polarization-maintaining time delay optical fiber ring 204 after two straight bunch polarised lights；The beam splitter 205 is matched
M the first output ends and m the second input terminals are equipped with, each of which first output end is connect with the input terminal of a sensing branch 1,
Each of which second input terminal is connect with the output end of a sensing branch 1；The beam splitter 205 is orthogonal by polarization direction
Two bunch polarised lights are divided into m route polarised light, obtain reflected light return after the sensing branch 1 per the linearly polarized light described all the way
To the beam splitter 205, the second output terminal of beam splitter 205 is connect with the second input terminal of the polarization-maintaining time delay optical fiber ring 204,
Reflected light exports after polarization-maintaining time delay optical fiber ring 204；It is described to be polarized and the second input terminal of coupled apparatus 203 and the polarization-maintaining
The second output terminal of time delay optical fiber ring 204 connects, and receives the reflected light that the beam splitter 205 exports, and reflected light is polarized described
And it interferes to export after obtaining interference light in coupler 203；Second input terminal of the optical transmission apparatus 202 is polarized with described
And the second output terminal connection of coupled apparatus 203, the second output terminal of the optical transmission apparatus 202 and the optical fiber filter 3
Input terminal connection；The optical transmission apparatus 202 receive it is described be polarized and interference light that coupled apparatus 203 exports after output to institute
State optical fiber filter 3.
It is understood that in the transmission process of above-mentioned optical signal or light beam, in addition to the reflected light of the sensing output of branch 1
Except, what is transmitted in optical path is the optical signal for including each wavelength, finally, the gating function of optical fiber filter 3 can be passed through, according to
The interference light of secondary selection different wave length enters in photodetector 4.
In above scheme, the optical transmission apparatus 202 is fiber optical circulator；Or, the optical transmission apparatus 202 includes optical fiber
Isolator and the fiber coupler being connect with the fibre optic isolater.Described its major function of optical transmission apparatus 202 is light letter
Number transmission, therefore the general device configured with corresponding optical signal input and output port, such as fiber optic loop can be used
Row device.In addition, the light of different transmission directions influences each other in order to prevent, if when using devices such as fiber couplers, it can be simultaneously
Increase optoisolator, can guarantee that reflected light signal will not generate interference to light source using optoisolator.
In addition, the beam splitter 205 in above scheme, major function is the optical signal that will be received on first direction
It is exported after being divided into multi beam, while the multi beam optical signal received on another direction is combined into a branch of rear output, can used
Broadband polarization-maintaining fiber coupler or polarization maintaining optical fibre wavelength division multiplexer, middle width strip polarization-maintaining fiber coupler and polarization maintaining optical fibre wavelength-division are multiple
With device, fast, slow axis work is supported simultaneously.
Further, described to be polarized and coupled apparatus 203 be realized by the following two kinds mode:
(1) it is polarized described in and coupled apparatus 203 includes optical fiber polarizer and straight waveguide phase modulator；The optical fiber is polarized
The tail optical fiber of the tail optical fiber of device and the straight waveguide phase modulator is using 45 ° to axis welding.
(2) it is polarized described in and coupled apparatus 203 includes Y waveguide phase-modulator and polarization beam combiner；The Y waveguide phase
One branch's tail optical fiber of one branch's tail optical fiber of modulator and polarization beam combiner is using 90 ° to axis welding；The Y waveguide phase tune
Another branch's tail optical fiber of another branch's tail optical fiber of device processed and polarization beam combiner is using 0 ° to axis welding.
From it is described be polarized and coupled apparatus 203 in the light beam that exports become the mutually orthogonal two bunch polarization in polarization direction
Light, the linearly polarized light transmit in polarization-maintaining time delay optical fiber ring, into the beam splitter 205 for having light beam splitting function, polarization direction
Mutually orthogonal linearly polarized light is respectively enterd and is transmitted in different sensing branches 1 after beam splitter 5.
Preferably, in above scheme, the optical fiber filter 3 can use fiber F-P filter, it is possible to understand that optical fiber F-
The gating wavelength of P filter can be configured by adjusting its scanning voltage, so even being different reflection type opticals
The back wave of fine grating with certain drift, can also be made by adjusting the scanning voltage of F-P filter its with it is corresponding anti-
Ejected wave length is adapted.The wavelength scanning range representative value of fiber F-P filter is tens nanometers, can cover the frequency of wide spectrum light source
Spectral limit, wavelength resolution is up to micromicron magnitude, and measuring instrument moderate cost, can meet the requirement of engineer application.Using
The specific implementation of the multiplex fibre optic current sensor of F-P optical fiber filter can be divided into multi-channel data acquisition and multichannel
Two step combination Fig. 5 of modulation /demodulation of signal distribute a time t for F-P filter for each sensing branch,
The above two steps operation is needed to be implemented in time t, therefore including between length scanning section and data collection zone:
(1) multi-channel data acquisition step
Multi-channel data acquisition method is specifically divided into two steps again, and the first step is to carry out central wavelength to multipath interference optical signal to sweep
It retouches, second step is to carry out data acquisition to the optical power of specific central wavelength.
Wherein, the concrete methods of realizing of central wavelength scanning is as follows: due to the reflection wavelength meeting of reflection-type optical fiber grating 103
Certain wavelength difference DELTA λ should be set as temperature is drifted about, therefore between the reflection wavelength of different sensing branches 1, and protected
Demonstrate,prove the temperature compensation range that range of temperature corresponding to this wavelength difference DELTA λ is more than fibre optic current sensor.That is, appointing
The difference DELTA λ of the reflection wavelength of reflection-type optical fiber grating in two sensing branch of meaning is all larger than Δ λmax；Wherein, Δ λmax=MAX
[Δλ1,Δλ2,……Δλm],ΔλiThe wavelength in temperature change of the reflection-type optical fiber grating in branch is sensed for i-th
Range of drift.When carrying out spatially selecting filtering using fiber F-P filter, gating bandwidth may be configured as just being equal to the wavelength difference,
As shown in Figure 3.λ in figure1For the reflection wavelength of reflection-type optical fiber grating 103 in a sensing branch 1, similarly λ2、λ3It is other two
The reflection wavelength of reflection-type optical fiber grating 103 in a sensing branch 1.Because the reflection wavelength of different reflection-type optical fiber gratings is all
The influence that will receive temperature change generates drift and influence degree is possible to different, therefore in this programme any two is reflected
The difference of wavelength is greater than the maximum value in the wave length shift of all reflection-type optical fiber gratings, can be avoided temperature change and gives optical fiber electricity
Flow sensor bring error.
In above scheme, optical fiber filter 103 determines the back wave of each reflection-type optical fiber grating by length scanning
The drift value of long central wavelength, it is further according to the reflection wavelength of reflection-type optical fiber grating and the relationship of its local environment temperature
Calculate the environment temperature of reflection-type optical fiber grating, and using this temperature as fibre optic current sensor in this sensing branch into
Temperature source when trip temperature error compensation.In addition, when fibre optic current sensor switches between different sensing branches, fiber F-P
The scanning voltage range of filter is different, and the scan period T of certain time width can be arranged according to the quantity of sensing branch, so that
All sensing branches can be scanned through in each cycle T.On entire time shaft, the multiplexing method of difference sensing branch is as schemed
Shown in 4, wherein Tn(n=1,2,3 ...) is n-th of scan period, λm(m=1,2,3 ...) is the anti-of m-th of sensing branch
Ejected wave is long.
By above method, the central wavelength of the corresponding interference light of multiple sensing branches can determine, and guarantee optical fiber
Filter only exports the interference light of a wavelength at any time, only corresponds to a sensing branch.
(2) modulation /demodulation of multiple signals
This step is realized that the optical signal that signal detection system exports photodetector is examined by signal detection system
It surveys, after the central wavelength and determining corresponding sensing branch for the interference light that optical fiber filter exports in step (1), makes light
The scanning voltage of fiber filter rests on accurate central wavelength strobe position, and photodetector exports optical fiber filter at this time
The light intensity of interference light carry out data acquisition, collected optical power can be used to demodulate tested current value.Timesharing can be used
Processing makes mutually indepedent between the signal processing of different sensing branches.Concrete methods of realizing are as follows:
(1) correct modulating frequency is set
The optical path transition time determines that the modulating frequency of signal detection system, optical path corresponding to difference sensing branch are getted over
Time is different, therefore need to debug the modulating frequency of each sensing branch correctly in calibration, and be written for signal processing
In chip, the scanning voltage section of optical fiber filter and the reflection wavelength of sensing branch are corresponded, each sensing branch
It is provided when modulating frequency is by demarcating, and also corresponding with the scanning voltage section of optical fiber filter, when the scanning of optical fiber filter
When voltage changes, corresponding modulating frequency is known by look-up table, is applied on phase-modulator, modulating frequency and scanning
The corresponding relationship of voltage is as shown in Figure 6.Wherein sensing branch 1 corresponds to reflected wavelength lambda1, scanning voltage corresponding to filter
For U0-U1, the modulating frequency of signal detection system is f1.Therefore, the corresponding relationship of above-mentioned data is stored in letter correspondingly
In number detection system.
(2) time division modulation and demodulation
Modulation and demodulation and data acquisition to optical signal carry out simultaneously, due to mutually only between the acquisition of each circuit-switched data
Vertical, therefore modulation and demodulation is also independent from each other, time-sharing method is as shown in fig. 7, P in figurenmFor in n-th of cycle period from
The m collected return optical power in sensing branch road, InmFor the demodulation current value for sensing branch in n-th of cycle period to m.
As previously mentioned, the current value in electrical conductor will affect the phase difference of two beam polarised lights in fiber optic loop, phase difference
Influence whether the interference of two beam polarised lights, interference light intensity corresponds to the electric signal that photodetector detects, therefore passes through demodulation
The electric signal of photodetector can be back-calculated to obtain corresponding current value.
The present embodiment is applied in combination using reflective fiber grating as reflecting element, and with optical fiber filter, due to anti-
Emitting fiber grating itself has good temperature sensitivity and an anti-electromagnetic interference capability, the central wavelength of reflection only with optical fiber
Temperature locating for grating is related with stress, when reflection-type optical fiber grating is set in device outside be necessarily provided with protection packaging,
Stress influence can be protected it from by protection packaging, thus the wavelength shift of reflection-type optical fiber grating can consider only with temperature
There is a relationship, therefore can determine the environment temperature locating for it using the drift value of reflection-type optical fiber optical grating reflection wavelength, and make
Temperature source when temperature error compensation is carried out for current value calculated result.At the same time, according to reflection-type optical fiber optical grating reflection wave
Long drift value counter can also push away in fiber optic loop the error term that generates due to magneto-optic coefficient variation, can be with using both the above method
It determines the error of faraday's phase shift in fiber optic loop, and then obtains the error of interference light intensity and the mistake of current value calculated result
Difference, error can be adjusted current value calculated result accordingly.It is hereby achieved that more accurate current value calculated result.
Finally, it should be noted that the above various embodiments is only to illustrate the technical solution of the utility model, rather than it is limited
System；Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should
Understand: it is still possible to modify the technical solutions described in the foregoing embodiments, or to some or all of
Technical characteristic is equivalently replaced；And these are modified or replaceed, it does not separate the essence of the corresponding technical solution, and this is practical new
The range of each embodiment technical solution of type.
Claims (7)
1. a kind of multi-channel optical fibre current sensor based on wavelength-division multiplex, which is characterized in that including m sensing branch, polarised light
Generating device, optical fiber filter and photodetector:
The sensing branch includes fiber optic loop and the optical-fibre wave plate and reflection-type optical fiber grating that the fiber optic loop both ends are arranged in；Institute
It states and is passed through inside fiber optic loop by electrical conductor；Wherein, the reflection-type optical fiber grating in the different sensing branches is for anti-
Penetrate the light beam of different wave length；
The polarised light generating device exports m route polarised light, and a sensing branch is entered per the linearly polarized light described all the way；
Each route polarised light includes the orthogonal two bunch polarised light in polarization direction；
In each sensing branch, the linearly polarized light is after the optical-fibre wave plate, the fiber optic loop by the reflection-type
It is obtained after fiber grating reflection, reflected light exports after the fiber optic loop and the optical-fibre wave plate；The wavelength of the reflected light with
The reflection wavelength of the reflection-type optical fiber grating is corresponding, and the reflected light includes that polarization direction is mutually perpendicular to and has phase difference
Two bunch polarised lights, the phase difference according in the electrical conductor electric current generate；
The linearly polarized light generating device receives the reflected light of each sensing branch output；Each reflected light
In two bunch polarised lights interfered in the linearly polarized light generating device, the interference light obtained after different reflecting interferences
Corresponding to different wavelength；
The optical fiber filter is configured with multiple optical channels, and the gating wavelength of different optical channels corresponds to the dry of different sensing branches
Relate to light；The optical fiber filter receives all interference lights of the linearly polarized light generating device output, successively according to setting sequence
Each optical channel output is connected to the interference light of inductive sensing branch；
The photodetector detects the light intensity of the interference light of the optical fiber filter output, and obtains corresponding with the light intensity
Electric signal, the electric signal are used to obtain the current value of the electrical conductor in phase inductive sensing branch.
2. the multi-channel optical fibre current sensor according to claim 1 based on wavelength-division multiplex, it is characterised in that:
The difference DELTA λ of the reflection wavelength of reflection-type optical fiber grating in any two sensings branch is all larger than Δ λmax；Wherein, Δ λmax
=MAX [Δ λ1,Δλ2,……Δλm],ΔλiIt is the reflection-type optical fiber grating in i-th of sensing branch in temperature change
Wave length shift range.
3. the multi-channel optical fibre current sensor according to claim 1 based on wavelength-division multiplex, which is characterized in that the polarization
Photogenerated device includes light source, optical transmission apparatus, is polarized and coupled apparatus, polarization-maintaining time delay optical fiber ring and beam splitter, in which:
The optical transmission apparatus, first input end are connect with the output end of the light source, and the first output end is polarized with described
And the first input end connection of coupled apparatus, the optical signal that the light source issues are transmitted to described be polarized through the optical transmission apparatus
And coupled apparatus；
It is described to be polarized and the first output end of coupled apparatus is connect with the first input end of the polarization-maintaining time delay optical fiber ring, the guarantor
First output end of inclined time delay optical fiber ring is connect with the first input end of the beam splitter；It is described to be polarized and coupled apparatus be described
Optical signal is converted to and is transmitted to described point through the polarization-maintaining time delay optical fiber ring after the orthogonal two bunch polarised light in polarization direction
Beam device；
The beam splitter is configured with second output terminal, m the first output ends and m the second input terminals, each of which first output end
It is connect with the input terminal of a sensing branch, each of which second input terminal connect the beam splitting with the output end of a sensing branch
The second output terminal of device is connect with the second input terminal of the polarization-maintaining time delay optical fiber ring；The beam splitter mutually hangs down polarization direction
Two straight bunch polarised lights are divided into m route polarised light, obtain reflected light after the sensing branch per the linearly polarized light described all the way
It is exported after being back to the beam splitter through the polarization-maintaining time delay optical fiber ring；
It is described to be polarized and the second input terminal of coupled apparatus is connect with the second output terminal of the polarization-maintaining time delay optical fiber ring, receive institute
State beam splitter output reflected light, reflected light it is described be polarized and coupler in interfere to obtain interference light after export；
Second input terminal of the optical transmission apparatus is polarized and the second output terminal of coupled apparatus is connect, the optical transport with described
The second output terminal of device is connect with the input terminal of the optical fiber filter；The optical transmission apparatus is polarized and couples described in receiving
It exports after the interference light of device output to the optical fiber filter.
4. the multi-channel optical fibre current sensor according to claim 3 based on wavelength-division multiplex, it is characterised in that:
The optical transmission apparatus is fiber optical circulator；Or,
The optical transmission apparatus includes fibre optic isolater and the fiber coupler that connect with the fibre optic isolater.
5. the multi-channel optical fibre current sensor according to claim 4 based on wavelength-division multiplex, it is characterised in that:
The beam splitter is broadband polarization-maintaining fiber coupler or polarization maintaining optical fibre wavelength division multiplexer.
6. according to the described in any item multi-channel optical fibre current sensors based on wavelength-division multiplex of claim 3-5, it is characterised in that:
It is described to be polarized and coupled apparatus includes optical fiber polarizer and straight waveguide phase modulator；The tail optical fiber of the optical fiber polarizer with
The tail optical fiber of the straight waveguide phase modulator is using 45 ° to axis welding.
7. according to the described in any item multi-channel optical fibre current sensors based on wavelength-division multiplex of claim 3-5, it is characterised in that:
It is described to be polarized and coupled apparatus includes Y waveguide phase-modulator and polarization beam combiner；The one of the Y waveguide phase-modulator
One branch's tail optical fiber of a branch's tail optical fiber and polarization beam combiner is using 90 ° to axis welding；The Y waveguide phase-modulator it is another
Another branch's tail optical fiber of a branch's tail optical fiber and polarization beam combiner is using 0 ° to axis welding.
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Cited By (2)
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| CN109405859A (en) * | 2018-12-17 | 2019-03-01 | 北京世维通光智能科技有限公司 | Multi-channel optical fibre current sensor and its control method, system based on wavelength-division multiplex |
| CN111308547A (en) * | 2020-03-21 | 2020-06-19 | 哈尔滨工程大学 | Six-dimensional seismic wave measuring device based on composite interferometer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109405859A (en) * | 2018-12-17 | 2019-03-01 | 北京世维通光智能科技有限公司 | Multi-channel optical fibre current sensor and its control method, system based on wavelength-division multiplex |
| CN111308547A (en) * | 2020-03-21 | 2020-06-19 | 哈尔滨工程大学 | Six-dimensional seismic wave measuring device based on composite interferometer |
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