CN110057307A - A kind of method and fibre optic interferometer improving fibre optic interferometer strain sensitivity - Google Patents
A kind of method and fibre optic interferometer improving fibre optic interferometer strain sensitivity Download PDFInfo
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- CN110057307A CN110057307A CN201910341775.8A CN201910341775A CN110057307A CN 110057307 A CN110057307 A CN 110057307A CN 201910341775 A CN201910341775 A CN 201910341775A CN 110057307 A CN110057307 A CN 110057307A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
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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
- G01D21/00—Measuring or testing not otherwise provided for
- G01D21/02—Measuring two or more variables by means not covered by a single other subclass
Abstract
The present invention discloses a kind of method and fibre optic interferometer for improving fibre optic interferometer strain sensitivity, and structure includes coupler, Polarization Controller and two sections of polarization maintaining optical fibres.The present invention introduces different optical path differences using two kinds of polarization maintaining optical fibres, when the length difference of two sections of polarization maintaining optical fibres meets preset condition, the spectrum of the structure will include different frequency components, to generate cursor effect, the spectrum of interference light is made of envelope spectrum and fine spectrum, the strain sensitivity of envelope spectrum increases compared to the strain sensitivity of the interferometer of single hop polarization maintaining optical fibre composition, greatly improves sensing sensitivity.The present invention cascades two sections of polarization maintaining optical fibres, sensitivity by calculating discovery sensor is determined by the length and intrinsic sensitivity of polarization maintaining optical fibre, compared with the interferometer based on single polarization maintaining optical fibre, in strain and temperature change differential responses occur for envelope and fine spectrum, with the potentiality for realizing strain and temperature synchro measure, and structure is simple, and it is easy to make, it is at low cost.
Description
Technical field
The present invention relates to technical field of optical fiber sensing, more particularly, to a kind of raising fibre optic interferometer strain sensitivity
Method and fibre optic interferometer.
Background technique
Fibre optic strain sensor is the important candidate of monitoring structural health conditions and distributed sensing application.It is passed with traditional strain
Sensing method is compared, and Fibre Optical Sensor has the characteristics that small in size, production is simple, electromagnetism interference, high resolution.Up to the present,
It has already been proposed many different types of fibre-optical sensing devices, such as fiber grating and fibre optic interferometer.It is answered in fiber grating
Become in sensor, fiber bragg grating (Fiber Bragg Grating, FBG) and long-period gratings (Long Period
Fiber Grating, LPG) it is all potential sensing element, and obtained extensive research.These sensors are easily fabricated, but
Strain sensitivity is low, and typical fiber-optic grating sensor strain sensitivity only has 1.2pm/ μ ε, based on long-period fiber grating
Strain transducer sensitivity only has 7.6pm/ μ ε.The sensitivity of interferometric optical fiber sensor is higher, but manufacturing process usually compares
It is complicated.In addition, cursor effect is a kind of method that can increase substantially sensitivity, but the sensor based on cursor effect is usual
Two independent interferometers are needed, structure is complicated.
One of the sensor is common problem encountered is that strain sensing will receive the interference of temperature.In order to solve this problem,
Multi parameter simultaneous measuring sensor based on matrix method becomes an attractive solution.A kind of feasible method is to set
Meter is based on multiple-mode interfence interferometer, and this method realizes that multi-parameter senses simultaneously using the difference of various modes, but this sensor
It is less reproducible.Another method is to cascade two individual fibers devices with different sensitivity, but this method still faces
The challenge that structure is complicated, at high cost.
Summary of the invention
In view of the drawbacks of the prior art, it is an object of the invention to solve existing fiber strain transducer high sensitivity with it is low
The technical issues of the problem of cost, simple structure cannot get both and strain sensing are easy by temperature interference.
To achieve the above object, in a first aspect, the present invention provides a kind of fibre optic interferometer, comprising: coupler, Polarization Control
Device, first segment polarization maintaining optical fibre and second segment polarization maintaining optical fibre；
The first end of the coupler receives input light, and input light is divided into two bundles by the coupler；
One end of the second end connection first segment polarization maintaining optical fibre of the coupler, the third end of the coupler connects polarization
One end of controller, one end of the other end connection second segment polarization maintaining optical fibre of the Polarization Controller, the first segment polarization-maintaining light
The fine other end is connected with the other end of second segment polarization maintaining optical fibre, the first segment polarization maintaining optical fibre fast axle and second segment polarization maintaining optical fibre
The angle of fast axle is predetermined angle；The coupler, Polarization Controller, first segment polarization maintaining optical fibre and second segment polarization maintaining optical fibre group
At fiber optic loop, the Polarization Controller is used to control the po-larization rotational angular introduced in fiber optic loop；
Input light is divided into two bundles by the coupler, a branch of to pass through the respectively along passing through fiber optic loop clockwise and anticlockwise
One section of polarization maintaining optical fibre to second segment polarization maintaining optical fibre returns to coupler, and another beam passes through second segment polarization maintaining optical fibre to first segment polarization-maintaining light
Fibre returns to coupler, and two beam input lights introduce phase difference when passing through two sections of polarization maintaining optical fibres, two beam input lights after returning to coupler
It interferes, obtains interference light；
4th end of the coupler exports interference light, when the length difference of first segment polarization maintaining optical fibre and second segment polarization maintaining optical fibre
When meeting preset condition, the spectrum of the interference light is made of envelope spectrum and fine spectrum, the strain sensitivity phase of the envelope spectrum
Strain sensitivity than the interferometer of single hop polarization maintaining optical fibre composition increases.
Optionally, the transmissivity of the interference light of the Sagnac fibre optic interferometer output are as follows:
Wherein, T indicates transmissivity, and first end to the first segment polarization maintaining optical fibre stitching portion that α and β respectively indicate coupler introduces
Po-larization rotational angular, β indicates the po-larization rotational angular that introduces to coupler third end stitching portion of second segment polarization maintaining optical fibre, θ expression institute
Predetermined angle is stated, B indicates the birefringence of two sections of polarization maintaining optical fibres, and λ indicates wavelength, the L of input light1Indicate first segment polarization maintaining optical fibre
Length, L2Indicate the length of second segment polarization maintaining optical fibre；
Work as L1And L2Difference be less than preset threshold when, it is described it is fine spectrum by high frequency period functionCertainly
Fixed, the envelope spectrum is by low-frequency cycle functionIt determines, forms tandem type cursor effect.
Optionally, the strain sensitivity K of the envelope spectrumε,EIt is sensitive with the strain of the interferometer of single hop polarization maintaining optical fibre composition
Spend KεMeet relational expression:L0Indicate the length for receiving effects of strain part in wherein one section of polarization maintaining optical fibre.
Optionally, the relationship that the wave length shift of the Sagnac fibre optic interferometer changes with parameter is expressed as follows:
Wherein, Δ λEWith Δ λFThe displacement for respectively indicating envelope spectrum and finely composing, Δ ε indicate strain variation amount, and Δ T is indicated
Temperature variation, Kε,EIndicate the strain sensitivity of envelope spectrum, Kε,FIndicate the strain sensitivity finely composed, KT,EIndicate envelope spectrum
Temperature sensitivity, KT,FIndicate the temperature sensitivity finely composed.
Optionally, the first segment polarization maintaining optical fibre and second segment polarization maintaining optical fibre are panda type polarization-preserving fiber.
Second aspect, the present invention provide a kind of method for improving fibre optic interferometer strain sensitivity, include the following steps:
Single hop polarization maintaining optical fibre in interferometer is replaced with into two sections of polarization maintaining optical fibres, two sections of polarization maintaining optical fibres are connected, and two
The angle of section polarization maintaining optical fibre fast axle is predetermined angle；
When the length difference of two sections of polarization maintaining optical fibres meets preset condition, via the interference obtained after two sections of polarization maintaining optical fibres effects
The spectrum of light is made of envelope spectrum and fine spectrum, generates cursor effect, and the strain sensitivity of the envelope spectrum compares single hop polarization-maintaining
The strain sensitivity of the interferometer of optical fiber composition increases.
Optionally, the length difference of two sections of polarization maintaining optical fibres meets preset condition, specifically: the length of two sections of polarization maintaining optical fibres
Difference is less than preset threshold；
The transmissivity of the interference light of the fibre optic interferometer output are as follows:
Wherein, T indicates transmissivity, and α indicates the polarization rotation that coupler first end to first segment polarization maintaining optical fibre stitching portion introduces
Corner, β indicate that the po-larization rotational angular that second segment polarization maintaining optical fibre is introduced to coupler third end stitching portion, θ indicate the preset angle
Degree, B indicate the birefringence of two sections of polarization maintaining optical fibres, and λ indicates wavelength, the L of input light1Indicate the length of first segment polarization maintaining optical fibre, L2
Indicate the length of second segment polarization maintaining optical fibre；
Work as L1And L2Difference be less than preset threshold when, it is described it is fine spectrum by high frequency period functionCertainly
Fixed, the envelope spectrum is by low-frequency cycle functionIt determines, forms tandem type cursor effect.
Optionally, the strain sensitivity K of the envelope spectrumε,EIt is sensitive with the strain of the interferometer of single hop polarization maintaining optical fibre composition
Spend KεMeet relational expression:L0Indicate the length for receiving effects of strain part in wherein one section of polarization maintaining optical fibre.
Optionally, the relationship that the wave length shift of 8 fibre optic interferometer changes with parameter is expressed as follows:
Wherein, Δ λEWith Δ λFThe displacement for respectively indicating envelope spectrum and finely composing, Δ ε indicate strain variation amount, and Δ T is indicated
Temperature variation, Kε,EIndicate the strain sensitivity of envelope spectrum, Kε,FIndicate the strain sensitivity finely composed, KT,EIndicate envelope spectrum
Temperature sensitivity, KT,FIndicate the temperature sensitivity finely composed.
Optionally, two sections of polarization maintaining optical fibres are panda type polarization-preserving fiber.
In general, through the invention it is contemplated above technical scheme is compared with the prior art, have below beneficial to effect
Fruit:
The present invention is cascaded using polarization maintaining optical fibre similar in two segment length, and fast axle angle is predetermined angle, and to wherein
One section of preset length carries out strain measurement, so that the interferometer of this structure is generated cursor effect, substantially increases the spirit of sensing
Sensitivity.
The present invention makes the knot by analyzing and being arranged suitable parameter by calculating the transmission function of cascade polarization maintaining optical fibre
What the transmission spectrum of structure was composed by envelope and finely forms, and respectively corresponds change and temperature change generates different reactions, realize strain
It is measured while with temperature, and has obtained the expression formula of sensitivity, eliminate influence of the temperature to strain sensitivity.
It is the configuration of the present invention is simple, easy to make, reproducible, at low cost, it can be used as one and be applied in Practical Project
Good selection.
Detailed description of the invention
Fig. 1 is the principle assumption diagram of fibre optic interferometer provided in an embodiment of the present invention；
Fig. 2 (a) is the strain sensing experimental principle figure of fibre optic interferometer provided in an embodiment of the present invention；
Fig. 2 (b) is the temperature sensing experimental principle figure of fibre optic interferometer provided in an embodiment of the present invention；
Fig. 3 is that the Sagnac fibre optic interferometer strain sensing provided in an embodiment of the present invention based on two polarization maintaining optical fibres is real
The relation schematic diagram of the envelope and the wave length shift finely composed and strain tested；
Fig. 4 is that the Sagnac fibre optic interferometer temperature sensing provided in an embodiment of the present invention based on two polarization maintaining optical fibres is real
The relation schematic diagram of the envelope and the wave length shift finely composed and temperature tested.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.As long as in addition, technical characteristic involved in the various embodiments of the present invention described below
Not constituting a conflict with each other can be combined with each other.
In current field there are aiming at the problem that, it is highly sensitive it is an object of the invention to solve existing fiber strain transducer
The problem of the problem of degree cannot get both with low cost, simple structure and strain sensing are easy by temperature interference.
To achieve the goals above, the invention proposes a kind of, and Sagnac (Sagnac) optical fiber based on cursor effect is dry
Interferometer, structure include three-dB coupler, general single mode fiber, Polarization Controller and two sections of polarization maintaining optical fibres.Wherein, Sagner
Gram it is a kind of classification of fibre optic interferometer, refers specifically to the light that light beam is divided into two beam reversals transmission, finally generate the ring of interference
Shape interferometer.
Specifically, the length of two sections of polarization maintaining optical fibres is respectively 28cm and 23cm.
Specifically, the angle of two sections of polarization maintaining optical fibre fast axles is 45 °.
Specifically, strain is measured using wherein one section of polarization maintaining optical fibre length is a part of 12.5cm.
Specifically, measurement while which can realize strain and temperature.
Specifically, which can produce cursor effect, greatly improve sensitivity, test the strain for measuring envelope and finely composing
Sensitivity is respectively 58.0pm/ μ ε and 5.9pm/ μ ε, and temperature sensitivity is respectively -1.05nm/ DEG C and -1.36nm/ DEG C.
Specifically, polarization maintaining optical fibre can choose panda type polarization-preserving fiber.
Fig. 1 is the principle assumption diagram of fibre optic interferometer provided in an embodiment of the present invention, as shown in Figure 1, wherein comprising tradition
Single mode optical fiber, three-dB coupler OC, Polarization Controller PC and two sections of polarization maintaining optical fibre (Polarization-maintaining
Fiber, PMF).In this structure, light is inputted from coupler one end, and after coupler, light is divided into two beams, respectively along suitable
Hour hands introduce phase differences, are returning to coupler after passing through ring with fiber optic loop, two sections of polarization maintaining optical fibres of passage in transit are passed through counterclockwise, hair
Raw interference, obtains interference spectrum.In order to study conveniently, discussion coupler coupling ratio be 0.5 the case where.
Wherein, Polarization Controller PC is used to control the po-larization rotational angular introduced in fiber optic loop.
Compared with general Sagnac interferometer, two sections of polarization maintaining optical fibres are welded together by this structure, insert optical fiber
In ring, instead of single polarization maintaining optical fibre.Polarization maintaining optical fibre so is cascaded to this section, is easy to get, it is propagated in light along different directions
When, Jones matrix is respectively as follows:
Wherein MCWAnd MCCWIt is the Jones matrix for cascading polarization maintaining optical fibre clockwise and anticlockwise respectively, θ is two
Angle between polarization maintaining optical fibre fast axle,WithIt is the phase difference that two sections of polarization maintaining optical fibres introduce respectively, meetsWherein, λ is wavelength, L1、L2It is the length of two PMF, B is the two-fold of polarization maintaining optical fibre
Penetrate rate.
Specifically, for two sections of polarization maintaining optical fibres other than length is different, other parameters are all the same.
In the case where coupling ratio is 0.5, the relationship of input light and output light be can simplify are as follows:
Wherein, Einx,Einy,EoutxAnd EoutyIt is the component of incident field and optical output field in x-axis and y-axis, α table respectively
Show that the po-larization rotational angular that the first end of coupler is introduced to first segment polarization maintaining optical fibre stitching portion, β indicate second segment polarization maintaining optical fibre extremely
The po-larization rotational angular that coupler third end stitching portion introduces.
Its transmissivity are as follows:
Joint type (1)-(5), the transmissivity of this available structure are as follows:
It can be seen that, two frequency components being contained in the spectrum of this structure by formula (6), weight can be determined by θ, alpha+beta,
Wherein θ is determined in two polarization maintaining optical fibre weldings, is no longer changed later, and alpha+beta can be adjusted by Polarization Controller, and Polarization Controller can be with
Adjust the summation of alpha+beta.Specifically, can control alpha+beta when experiment is π/4.
If the optical path difference of two polarization maintaining optical fibres is close, cos [π B (L1+L2)/λ] a high frequency period function can be regarded as,
cos[πB(L1-L2)/λ] low-frequency cycle function can be regarded as.It can be seen that final spectrum includes that a high frequency is finely composed, by
cos[πB(L1+L2)/λ] it determines.Additionally it contained a lower-frequency envelope, mainly by cos [π B (L1-L2)/λ] it determines.This structure
Tandem type cursor effect can be formed, has amplification effect to sensitivity and dynamic range.
In one example, in order to generate cursor effect, PMF1Length PMF should be set2Near, as mentioning above
To experiment in the parameter that is arranged are as follows: L1=28cm, L2=23cm, B=0.0006, θ=45 °, structure are as shown in Figure 1.
Based on the sensor of cascade PMF, in sensing process, strain is applied to a PMF, temperature is applied to two PMF
Variation.With temperature or the variation of strain, envelope and fine spectrum can be all subjected to displacement, by determining envelope and fine spectral peak
Formula is analyzed, and the displacement of spectrum can be calculated.
For the single Sagnac interferometer based on PMF, when strain or temperature change, spectrum can be subjected to displacement.It answers
The calculation formula of sensibility variable and temperature sensitivity:
Wherein, B indicates that the double refractive inde of PMF, L indicate the length of PMF, and Δ ε is strain variation amount, Δ λεIndicate this
The corresponding wave length shift of strain variation, Δε(BL) indicate that the corresponding optical path difference of this section of polarization maintaining optical fibre changes in the strain applied
Variation afterwards, KεIndicate the strain sensitivity of PMF.Similarly, Δ T is temperature variation, Δ λTIndicate that this temperature change is corresponding
Wave length shift, ΔT(BL) variation of the corresponding optical path difference of this section of polarization maintaining optical fibre after ambient temperature change, K are indicatedTIndicate PMF's
Temperature sensitivity.
It is L using length in wherein one section of polarization maintaining optical fibre for cascade PMF0A part come detect strain.Strain is drawn
The envelope displacement of the lines risen can indicate are as follows:
Δλε,EIndicate wavelength shift of the envelope under strain variation, Kε,EIndicate the strain sensitivity of envelope, L1, L2Point
Not Biao Shi two sections of PMF length, Δε(BL0) indicate this section of L0The corresponding optical path difference of the PMF of length is after external world's strain changes
Variation.Comparison expression (7) and (9), the envelope sensitivity of available cascade PMF and the sensitivity of PMF meet relationship:
Work as L1And L2When relatively, sensitivity is amplified.This cursor effect bring amplification for embodying cascade PMF is made
With magnification M are as follows:
And it finely composes by cos [π B (L1+L2)/λ] it determines, it is sensitive that the strain finely composed can be similarly calculated with formula (7) comparison
Spend Kε,FAre as follows:
In temperature measurement, two sections of optical fiber are all used to experience temperature change, and two sections of optical fiber also can all generate optical path difference change
Change.It is compared with formula (8), envelope spectrum temperature sensitivity can indicate respectively with fine spectrum temperature sensitivity are as follows:
Wherein, KT,ERepresent the temperature sensitivity of envelope spectrum, KT,FRepresent the temperature sensitivity finely composed, ΔT[B(L1-
L2)], ΔT[B(L1+L2)] optical path difference for the PMF introducing that length is corresponded in envelope spectrum and fine spectrum is respectively indicated in temperature change
Variation afterwards.
By formula (10), (12), (13), (14) be can see, and in strain measurement, the envelope spectrum for cascading PMF has vernier
The amplified strain sensitivity of effect, fine spectrum have the strain sensitivity after reducing.In temperature measurement, the packet of PMF is cascaded
Network spectrum and fine spectrum suffer from temperature sensitivity identical with list PMF.The notable difference of this sensitivity make it have strain and
The potentiality of temperature simultaneously measuring, the relationship that wave length shift changes with parameter can be provided by following cross matrix:
Wherein, Δ λEWith Δ λFIt is the displacement for the envelope and fine lines measured.
In order to verify the actual performance of the sensor, strain and temperature measurement experiment have been carried out.Strain sensing experimental provision
Shown in schematic diagram such as Fig. 2 (a).In order to observe the real time spectrum of optical fiber structure, contained in device a spectrometer (OSA,
Yokogawa AQ6370c) He Yitai wide spectrum light source (BBS), it is strained to apply to optical fiber, has used two optical fiber in experiment
Adjusting bracket can fix optical fiber and make small displacement.In experiment, structure of fiber_optic is fixed on PMF is sensed on platform, two-stage
Between primary leading be L0=12.5cm, that is, the length for receiving strain is L0=12.5cm, adjustable minimum step are 10
μm, the corresponding stress for applying 80 μ ε.In addition, Fig. 2 (b) is the experimental provision for measuring temperature, spectrometer OSA and width have equally been used
Spectrum light source BBS to observe spectrum in real time.In order to apply temperature change, thermoelectric cooler (Thermal Electric is used
Cooler, TEC), it is 0.1 DEG C that minimum temperature, which adjusts step-length,.Firstly, being carried out to the Sagnac interferometer based on single PMF
Temperature and strain sensing experiment, using linear fit, in one experiment, the sensitivity measure of strain and temperature is 20pm/ μ ε
With -1.38nm/ DEG C.
Then the Sagnac interferometer based on two PMF is tested.Strain changes with the relationship of wave length shift such as
Shown in Fig. 3.After linear fit, envelope spectrum and the strain sensitivity finely composed are respectively 58.0pm/ μ ε and 5.9pm/ μ ε, compared to single
The Sagnac interferometer of a PMF, envelope spectral sensitivity are greatly improved, and fine spectral sensitivity slightly reduces, with theory point
Analysis is consistent.Sensitivity magnification M=2.9 can be calculated, the amplification coefficient that formula (11) is predicted is 2.5, theoretical value and experiment
Measured value is consistent substantially, and existing error may be inaccurate caused by optical fiber length measuring.
Experiment also demonstrates the temperature performance of the structure.Two sections of PMF are placed on TEC, are heated to respectively from 20 DEG C
80 DEG C, step-length is 5 DEG C.After obtaining the spectrum under different temperatures, can with strain measurement test in identical method wrapped
Network and the drift finely composed, temperature and the relationship that wave crest is displaced are as shown in Figure 4.It is obvious that when the temperature increases, envelope and fine
Spectrum is all mobile to shorter wavelength direction.By linear fit, obtain envelope and the temperature sensitivity finely composed be respectively-
1.05nm/ DEG C and -1.36nm/ DEG C.As shown in experiment above, the temperature sensitivity of single PMF is -1.38nm/ DEG C, basic to differ
Less, consistent with theory analysis, illustrate the temperature sensitivity and the temperature sensitive of list PMF that cascade the envelope spectrum of PMF and finely compose
It spends approximately uniform.According to strain and temperature sensitivity that experiment obtains, strain and temperature synchro measure may be implemented.
The present invention discloses a kind of Sagnac fibre optic interferometer based on cursor effect, and structure includes three-dB coupler, general
Logical single mode optical fiber, Polarization Controller and two segment length are respectively the polarization maintaining optical fibre of 28cm and 23cm.The present invention is using two kinds of guarantors
Polarisation fibre introduces different optical path differences, therefore the spectrum of the structure is by comprising different frequency components, so that cursor effect is generated,
Greatly improve sensing sensitivity.The present invention cascades two sections of polarization maintaining optical fibres, by the sensitivity for calculating discovery sensor
It is determined by the length and intrinsic sensitivity of polarization maintaining optical fibre, compared with the interferometer based on single polarization maintaining optical fibre, envelope and fine spectrum
Differential responses occur in strain and temperature change, therefore there are the potentiality for realizing strain and temperature synchro measure, and structure letter
It is single, it is easy to make, it is at low cost.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.
Claims (10)
1. a kind of fibre optic interferometer characterized by comprising coupler, Polarization Controller, first segment polarization maintaining optical fibre and second
Section polarization maintaining optical fibre；
The first end of the coupler receives input light, and input light is divided into two bundles by the coupler；
One end of the second end connection first segment polarization maintaining optical fibre of the coupler, the third end of the coupler connects Polarization Control
One end of device, one section of the other end connection second segment polarization maintaining optical fibre of the Polarization Controller, the first segment polarization maintaining optical fibre
The other end is connected with the other end of second segment polarization maintaining optical fibre, the first segment polarization maintaining optical fibre fast axle and second segment polarization maintaining optical fibre fast axle
Angle be predetermined angle；The coupler, Polarization Controller, first segment polarization maintaining optical fibre and second segment polarization maintaining optical fibre form light
Fine ring, the Polarization Controller are used to control the po-larization rotational angular introduced in fiber optic loop；
Input light is divided into two bundles by the coupler, and edge passes through fiber optic loop clockwise and anticlockwise respectively, a branch of to pass through first segment
Polarization maintaining optical fibre to second segment polarization maintaining optical fibre returns to coupler, and another beam passes through second segment polarization maintaining optical fibre to first segment polarization maintaining optical fibre and returns
To coupler, two beam input lights introduce phase difference when passing through two sections of polarization maintaining optical fibres, and two beam input lights after returning to coupler occur
Interference, obtains interference light；
4th end of the coupler exports interference light, when the length difference of first segment polarization maintaining optical fibre and second segment polarization maintaining optical fibre meets
When preset condition, the spectrum of the interference light is made of envelope spectrum and fine spectrum, and the strain sensitivity of the envelope spectrum is compared to single
The strain sensitivity of the interferometer of section polarization maintaining optical fibre composition increases.
2. fibre optic interferometer according to claim 1, which is characterized in that the Sagnac fibre optic interferometer output is done
Relate to the transmissivity of light are as follows:
Wherein, T indicates transmissivity, and α indicates the polarization rotation that first end to the first segment polarization maintaining optical fibre stitching portion of coupler introduces
Angle, β indicate that the po-larization rotational angular that second segment polarization maintaining optical fibre is introduced to coupler third end stitching portion, θ indicate the predetermined angle,
B indicates the birefringence of two sections of polarization maintaining optical fibres, and λ indicates wavelength, the L of input light1Indicate the length of first segment polarization maintaining optical fibre, L2Table
Show the length of second segment polarization maintaining optical fibre；
Work as L1And L2Difference be less than preset threshold when, it is described it is fine spectrum by high frequency period functionIt determines, institute
Envelope spectrum is stated by low-frequency cycle functionIt determines, forms tandem type cursor effect.
3. fibre optic interferometer according to claim 2, which is characterized in that the strain sensitivity K of the envelope spectrumε,EWith list
The strain sensitivity K of the interferometer of section polarization maintaining optical fibre compositionεMeet relational expression:L0Indicate wherein one section
Receive the length of effects of strain part in polarization maintaining optical fibre.
4. fibre optic interferometer according to claim 3, which is characterized in that the wavelength of the Sagnac fibre optic interferometer floats
The relationship changed with parameter is moved to be expressed as follows:
Wherein, Δ λEWith Δ λFThe displacement for respectively indicating envelope spectrum and finely composing, Δ ε indicate strain variation amount, and Δ T indicates temperature
Variable quantity, Kε,EIndicate the strain sensitivity of envelope spectrum, Kε,FIndicate the strain sensitivity finely composed, KT,EIndicate the temperature of envelope spectrum
Spend sensitivity, KT,FIndicate the temperature sensitivity finely composed.
5. fibre optic interferometer according to any one of claims 1 to 4, which is characterized in that two sections of polarization maintaining optical fibres are panda
Type polarization maintaining optical fibre.
6. a kind of method for improving fibre optic interferometer strain sensitivity, which comprises the steps of:
Single hop polarization maintaining optical fibre in interferometer is replaced with into two sections of polarization maintaining optical fibres, two sections of polarization maintaining optical fibres are connected, two sections of guarantors
The angle of polarisation fibre fast axle is predetermined angle；
When the length difference of two sections of polarization maintaining optical fibres meets preset condition, via the interference light obtained after two sections of polarization maintaining optical fibres effects
Spectrum is made of envelope spectrum and fine spectrum, and the strain sensitivity of the envelope spectrum is compared to the interferometer that single hop polarization maintaining optical fibre forms
Strain sensitivity increases.
7. the method according to claim 6 for improving fibre optic interferometer strain sensitivity, which is characterized in that two sections of guarantors
The length difference of polarisation fibre meets preset condition, specifically: the length difference of two sections of polarization maintaining optical fibres is less than preset threshold；
The transmissivity of the interference light of the fibre optic interferometer output are as follows:
Wherein, T indicates transmissivity, and α indicates the polarization rotation that first end to the first segment polarization maintaining optical fibre stitching portion of coupler introduces
Angle, β indicate that the po-larization rotational angular that second segment polarization maintaining optical fibre is introduced to coupler third end stitching portion, θ indicate the predetermined angle,
B indicates the birefringence of two sections of polarization maintaining optical fibres, and λ indicates wavelength, the L of input light1Indicate the length of first segment polarization maintaining optical fibre, L2Table
Show the length of second segment polarization maintaining optical fibre；
Work as L1And L2Difference be less than preset threshold when, it is described it is fine spectrum by high frequency period functionIt determines, institute
Envelope spectrum is stated by low-frequency cycle functionIt determines, forms tandem type cursor effect.
8. the method according to claim 7 for improving fibre optic interferometer strain sensitivity, which is characterized in that the envelope spectrum
Strain sensitivity Kε,EWith the strain sensitivity K of the interferometer of single hop polarization maintaining optical fibre compositionεMeet relational expression:L0Indicate the length for receiving effects of strain part in wherein one section of polarization maintaining optical fibre.
9. the method according to claim 8 for improving fibre optic interferometer strain sensitivity, which is characterized in that 8 optical fiber
The relationship that the wave length shift of interferometer changes with parameter is expressed as follows:
Wherein, Δ λEWith Δ λFThe displacement for respectively indicating envelope spectrum and finely composing, Δ ε indicate strain variation amount, and Δ T indicates temperature
Variable quantity, Kε,EIndicate the strain sensitivity of envelope spectrum, Kε,FIndicate the strain sensitivity finely composed, KT,EIndicate the temperature of envelope spectrum
Spend sensitivity, KT,FIndicate the temperature sensitivity finely composed.
10. according to the described in any item methods for improving fibre optic interferometer strain sensitivity of claim 6 to 9, which is characterized in that
Two sections of polarization maintaining optical fibres are panda type polarization-preserving fiber.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111122512A (en) * | 2019-12-20 | 2020-05-08 | 天地（常州）自动化股份有限公司 | Polypyrrole coating optical fiber volatile organic compound sensor and manufacturing method thereof |
| CN113358037A (en) * | 2021-08-10 | 2021-09-07 | 中国计量科学研究院 | Laser displacement measuring device and method |
| CN114460044A (en) * | 2022-02-18 | 2022-05-10 | 北京航空航天大学 | Reflection type all-fiber hydrogen concentration and humidity sensor |
| CN116105778A (en) * | 2023-04-12 | 2023-05-12 | 广东海洋大学深圳研究院 | Optical fiber sensing system for synchronous measurement of temperature and salt |
| US11965821B1 (en) | 2023-04-12 | 2024-04-23 | Guangdong Ocean University | Optical fiber sensing system for temperature and salinity synchronous measurement |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2676226Y (en) * | 2003-12-17 | 2005-02-02 | 中国科学院上海光学精密机械研究所 | Multipurpose full gloss optical reshaper based on Sagnarc ring |
| CN106768474A (en) * | 2016-12-15 | 2017-05-31 | 中国计量大学 | The method and device of vernier enlarge-effect is produced based on single Sagnac interference rings |
| CN206656954U (en) * | 2017-04-21 | 2017-11-21 | 中国计量大学 | A kind of Sagnac interference-type optical fiber hydrogen gas sensors based on vernier enlarge-effect |
| CN107894245A (en) * | 2017-12-11 | 2018-04-10 | 哈尔滨工程大学 | A kind of polarization maintaining optical fibre interferometer strained with temperature simultaneously measuring |
| CN209820413U (en) * | 2019-04-26 | 2019-12-20 | 华中科技大学 | Optical fiber interferometer |
-
2019
- 2019-04-26 CN CN201910341775.8A patent/CN110057307B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2676226Y (en) * | 2003-12-17 | 2005-02-02 | 中国科学院上海光学精密机械研究所 | Multipurpose full gloss optical reshaper based on Sagnarc ring |
| CN106768474A (en) * | 2016-12-15 | 2017-05-31 | 中国计量大学 | The method and device of vernier enlarge-effect is produced based on single Sagnac interference rings |
| CN206656954U (en) * | 2017-04-21 | 2017-11-21 | 中国计量大学 | A kind of Sagnac interference-type optical fiber hydrogen gas sensors based on vernier enlarge-effect |
| CN107894245A (en) * | 2017-12-11 | 2018-04-10 | 哈尔滨工程大学 | A kind of polarization maintaining optical fibre interferometer strained with temperature simultaneously measuring |
| CN209820413U (en) * | 2019-04-26 | 2019-12-20 | 华中科技大学 | Optical fiber interferometer |
Non-Patent Citations (3)
| Title |
|---|
| HAO LIAO等: "Sensitivity amplification of fiber-optic in-line Mach–Zehnder Interferometer sensors with modified Vernier-effect", OPTICS EXPRESS, vol. 25, no. 22 * |
| 杨远洪;刘硕;陆林;靳伟;: "基于保偏光子晶体光纤Sagnac干涉仪的温度不敏感压力传感技术", 红外与激光工程, no. 08 * |
| 樊帆;赵建林;文喜星;姜碧强;: "强度解调型光纤光栅法布里-珀罗干涉仪的应变传感灵敏度分析", 中国激光, no. 06 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111122512A (en) * | 2019-12-20 | 2020-05-08 | 天地（常州）自动化股份有限公司 | Polypyrrole coating optical fiber volatile organic compound sensor and manufacturing method thereof |
| CN113358037A (en) * | 2021-08-10 | 2021-09-07 | 中国计量科学研究院 | Laser displacement measuring device and method |
| CN113358037B (en) * | 2021-08-10 | 2021-11-09 | 中国计量科学研究院 | Laser displacement measuring device and method |
| CN114460044A (en) * | 2022-02-18 | 2022-05-10 | 北京航空航天大学 | Reflection type all-fiber hydrogen concentration and humidity sensor |
| CN116105778A (en) * | 2023-04-12 | 2023-05-12 | 广东海洋大学深圳研究院 | Optical fiber sensing system for synchronous measurement of temperature and salt |
| US11965821B1 (en) | 2023-04-12 | 2024-04-23 | Guangdong Ocean University | Optical fiber sensing system for temperature and salinity synchronous measurement |
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