CN105424252B - A kind of fiber grating surge sensor and processing method - Google Patents
A kind of fiber grating surge sensor and processing method Download PDFInfo
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- CN105424252B CN105424252B CN201510999979.2A CN201510999979A CN105424252B CN 105424252 B CN105424252 B CN 105424252B CN 201510999979 A CN201510999979 A CN 201510999979A CN 105424252 B CN105424252 B CN 105424252B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/0052—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes measuring forces due to impact
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
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Abstract
The present invention relates to field of measuring technique, especially a kind of fiber grating surge sensor and processing method.The technical problem to be solved by the present invention is to：For utilization unequal arm optical fiber Mach Zehnder interference devices, cause the wavelength of fiber grating to move surge and is converted to interference signal, to detect the measurement method of phase difference there are the shortcomings that, it is proposed that a kind of side-hole fiber grating sensor measures surge.Light pulse signal in the present invention by three port circulator third port outputs carries out two level amplification, is exported to signal processing apparatus after being carried out at the same time signal delay；Signal processing apparatus receives the optical signal that amplification and delay singly export, and light pulse signal is converted to by electric signal by the photoelectric converter of signal processing apparatus, then after being recorded by the oscillograph of signal processing apparatus, calculating shock wave pressure is carried out by the processor of signal processing apparatus.
Description
Technical field
The present invention relates to field of measuring technique, especially a kind of fiber grating surge sensor and processing method.
Background technology
In Shock wave physics, detonation physics field, the accurate surge that measures closes the equation of state of material and this structure
System, burning-detonation conversion, high explosive Impact Initiation and the detonation property of the explosive containing energy, the impact phase transition of material and material are dynamic
State is damaged and the researchs such as fracture are of great significance.The accurate surge measured in medium is to conventional weapon designing technique, broken
Bad effect is studied and new material research has direct reference significance.
Document<The surge in explosive is measured using fiber-optic grating sensor>(P.G.Van't Hof,L.K.Cheng,
J.H.G.Schopltes,W.C.Prinse.Dynamic Pressure Measurement of Shock Waves in
Explos ives by Means of a Fiber Bragg Grat ing Sensor,Proc.of SPIE Vol.6279,
62791Y, (2007) 0277-786/07.) it has reported using unequal arm optical fiber Mach-Zehnder interference device, by surge
Cause the wavelength of fiber grating to move and be converted to interference signal, to detect the measurement method of phase difference.The institute of document report
It is about 1GPa to survey peak impact pressure, and system time resolving power is sub-micro second-time.The technology has the following disadvantages：1) system
Time resolution sheet is sub-micro second-time, is difficult complete response to fast impact process, causes signal " distortion ", even " lose "；2)
Advance Accurate Calibration pressure-volume curve is needed, surge otherwise can not be calculated；3) it is difficult accurately by unequal arm optical fiber
The optical path difference of Mach-Zehnder interference devices is controlled in 1 ± 0.1mm or so；4) peak value of surveyed surge is too small, about
1GPa。
Invention content
The technical problem to be solved by the present invention is to：It, will for unequal arm optical fiber Mach-Zehnder interference device is utilized
Surge causes the wavelength movement of fiber grating to be converted to interference signal, is lacked existing for the measurement method of phase difference to detect
Point proposes a kind of side-hole fiber grating sensor to measure surge.Its specific invention content is as follows：
1) cause the wavelength of fiber grating to move (transient state spectrum signal) surge and be converted to time-domain signal, then pass through
Photodetector and digital oscilloscope complete signal record；
2) time-domain signal is converted to by transient state spectrum signal using dispersion Fourier Transform Technique, to obtain surge
The wavelength of fiber grating is caused to move.
The technical solution adopted by the present invention is as follows：
A kind of fiber grating surge sensor includes：
Laser, for generating repetition, Femtosecond Optical Pulses, time domain waveform is as shown in Fig. 2, its spectrum is as shown in Figure 3.
Three port circulators, for receiving the femto-second laser pulse that laser generates by three port circulator first ports
Signal, and pass through three port circulator second port outputs；The light pulse exported from three port circulator second ports is lateral opening
After fiber grating reflection, spectrum will be split into two narrow " Gauss " pulse；Its spectral shape is as shown in Figure 4.When side-hole fiber light
When grid are by percussion, the wavelength interval Δ λ of two narrow " Gauss " shape pulse will change；By side-hole fiber optical grating reflection
Light pulse afterwards is exported from three port circulator third ports to amplification and dispersion list from three port circulator second port inputs
Member；
Amplification and dispersion element, for the light pulse of three port circulator third ports outputs to be amplified, then into
Row dispersion Fourier transformation is by the progress two level amplification after being transformed to time-domain signal of light pulse, finally by amplified time-domain signal
It exports to signal processing apparatus；
Signal processing apparatus, the time-domain signal for receiving amplification and dispersion element output, and pass through signal processing apparatus
Photoelectric converter time-domain signal is converted into electric signal, then by the oscillograph recording electric signal of signal processing apparatus after,
Data processing is carried out again, and shock wave pressure is finally calculated according to formula (1)：
Δ λ=KP·P (1)
Wavelength interval Δ λ between " Gauss shape " spectrum of two of which separation is only related with shock wave pressure P, KPFor wave
Length-pressure-constant has substantial connection with the material of side-hole fiber grating, structure..
Further, the amplification and delay cell include for carrying out the erbium-doped fiber amplifier of signal amplification, being used for
The preposition raman amplifier of signal amplification, the optical fiber for carrying out dispersion Fourier transformation and the postposition Raman for signal amplification are put
Big device.
Further, after the oscillograph recording electric signal of described processing unit, then data processing is carried out, according to formula
(1) calculating the detailed process of shock wave pressure is：
Step 21：The time-domain signal I (t) of oscillograph recording is periodic signal, and cycle T is the repetition frequency of femto-second laser
The inverse of rate；Time-domain signal I in i-th of periodi(t) corresponding frequency-region signal is Ii(λ), and time-domain signal when
Between the wavelength X of t and frequency-region signal have the relationships of formula (2)：
Wherein c is vacuum light speed；λ0For the centre wavelength of laser, λ is the non-central wavelength of laser, between center
Near wavelength；Z is fiber lengths；β1、β2Respectively it is the inverse and group velocity dispersion of group velocity of the optical fiber under centre wavelength；
Step 22：If Ii(t)、IiThe interval of two separation " Gauss " pulses of (λ) is respectively Δ ti、Δλi, then they have
The relationship of formula (3).
In formula, D is dispersion parameter, with group velocity dispersion β2Relationship：
Step 23：According to formula (1), by IiThe wavelength interval Δ λ of (λ)iDivided by wavelength-pressure-constant KP, so that it may it is somebody's turn to do
Pressure P in periodi。
Further, the step 22 includes：
Step 221：By Ii(t) t at the time of two separation " Gauss " peak value of pulses correspond toi1、ti2Bring the right side of formula (2) into
Side, and by Ii(λ) corresponding two peak wavelength λi1、λi2Bringing the left side of formula (2) into can obtain：
Step 222：The both sides of formula (5), formula (4) are subtracted each other, can be obtained
Formula (6) left side is deformed, can be obtained
Step 223：Formula (7) is brought into the left side of formula (6) to be obtained：
It enablesThen formula (8) is transformed to formula (3), obtains Δ λi：
Further, the laser repetition rate is 50MHZ~200MHz；Line width is 50nm~100nm；Mean power
For 50mW~200mW；The rise time of pulse is 1ps~100fs；Centre wavelength is 1550nm.
A kind of fiber grating surge processing method includes：
Step 1：Femtosecond laser signal is generated by laser；
Step 2：Three port circulators receive the femtosecond laser arteries and veins that laser generates by three port circulator first ports
Signal is rushed, and passes through three port circulator second port outputs；The light pulse exported from three port circulator second ports is by side
After the fiber grating reflection of hole, spectrum will be split into two narrow " Gauss " pulse, and spectral shape is as shown in Figure 4.Work as side-hole fiber
When grating is by percussion, the wavelength interval Δ λ of two narrow " Gauss " pulse will change；By side-hole fiber optical grating reflection
Light pulse afterwards is exported from three port circulator third ports to amplification and dispersion list from three port circulator second port inputs
Member；
Step 3：It is used to put the light pulse of three port circulator third port outputs by amplification and delay cell
Greatly, it then carries out carrying out two level amplification after frequency-region signal is transformed to time-domain signal by dispersion Fourier transformation, after finally amplifying
Time-domain signal export to signal processing apparatus；
Step 4：The time-domain signal of amplification and dispersion element output is received by signal processing apparatus, and passes through signal processing
Time-domain signal is converted to electric signal by the photoelectric converter of device, then passes through the oscillograph recording electric signal of signal processing apparatus
Afterwards, then data processing is carried out, shock wave pressure is finally calculated according to formula (1)：
Δ λ=Kp·P (1)
Wavelength interval Δ λ between " Gauss " spectrum of two of which separation is only related with shock wave pressure P, KPFor wave
Length-pressure-constant.
Further, the amplification and delay cell include for carrying out the erbium-doped fiber amplifier of signal amplification, being used for
The preposition raman amplifier of signal amplification, the dispersive optical fiber for carrying out dispersion Fourier transformation and the postposition for signal amplification are drawn
Graceful amplifier.
Further, after the oscillograph recording electric signal of the signal processing apparatus, then data processing is carried out, last basis
Formula (1) calculate shock wave pressure detailed process be：
Step 21：The time-domain signal I (t) of oscillograph recording is periodic signal, and cycle T is the repetition frequency of femto-second laser
The inverse of rate；Time-domain signal I in i-th of periodi(t) corresponding frequency-region signal is Ii(λ), and time-domain signal when
Between the wavelength X of t and frequency-region signal have the relationships of formula (2)：
Wherein c is vacuum light speed；λ0For the centre wavelength of laser, λ is the non-central wavelength of laser, between center
Near wavelength；Z is fiber lengths；β1、β2Respectively it is the inverse and group velocity dispersion of group velocity of the optical fiber under centre wavelength；
Step 22：If Ii(t)、IiThe interval of two separation " Gauss " pulses of (λ) is respectively Δ ti、Δλi, then they have
The relationship of formula (3).
In formula, D is dispersion parameter, with group velocity dispersion β2Relationship：
Step 23：According to formula (1), by IiThe wavelength interval Δ λ of (λ)iDivided by wavelength-pressure-constant KP, so that it may it is somebody's turn to do
Pressure P in periodi。
Further, the step 22 includes：
Step 221：By Ii(t) t at the time of two separation " Gauss " peak value of pulses correspond toi1、ti2Bring the right side of formula (2) into
Side, and by Ii(λ) corresponding two peak wavelength λi1、λi2Bringing the left side of formula (2) into can obtain：
Step 222：The both sides of formula (5), formula (4) are subtracted each other, can be obtained
Formula (6) left side is deformed, can be obtained
Step 223：Formula (7) is brought into the left side of formula (6) to be obtained：
It enablesThen formula (8) is transformed to formula (3), obtains Δ λi：
Further, the laser repetition rate is 50MHZ~200MHz；Line width is 50nm~100nm；Mean power
For 50mW~200mW；The rise time of pulse is 1ps~100fs；Centre wavelength is 1550nm.
In conclusion by adopting the above-described technical solution, the beneficial effects of the invention are as follows：
1) this sensor survey surge pressure be increased to 10GPa ((can measuring pressure peak value be laser line width/it is lateral opening
Pressure-wavelength constant of fiber grating) left and right, expand the measurement range of fiber bragg grating pressure sensor.
2) system response time, can be more up to 10ns (system response time is the inverse of laser repetition rate) left and right
Truly respond impact process；
3) this sensor use side-hole fiber grating wavelength movement only with the wired sexual intercourse of surge, and and temperature
It is unrelated, therefore the sensor does not need nominal pressure-volume curve.
Description of the drawings
Examples of the present invention will be described by way of reference to the accompanying drawings, wherein：
Fig. 1 is the structure diagram of side-hole fiber grating surge sensor of the present invention.
Fig. 2 is the output optical pulse schematic diagram of laser
Fig. 3 is the spectral schematic of laser
Fig. 4 is the reflectance spectrum figure of side-hole fiber grating.
Fig. 5 is the time-domain signal figure of oscillograph recording.
Fig. 6 is frequency domain signal diagrams.
Specific implementation mode
All features disclosed in this specification or disclosed all methods or in the process the step of, in addition to mutually exclusive
Feature and/or step other than, can combine in any way.
Any feature disclosed in this specification (including any accessory claim, abstract and attached drawing), except non-specifically chatting
It states, can be replaced by other alternative features that are equivalent or have similar purpose.That is, unless specifically stated, each feature is only
It is an example in a series of equivalent or similar characteristics.
Related description of the present invention：
1, the technical indicator of main components is as follows：
A) laser in the present invention is repetition mode locking femto-second laser, and important technological parameters are：1) repetition rate：
50MHZ-200MHz；2) line width：50nm-100nm；3) mean power：50mW-200mW；4) rise time of pulse：50fs-
1000fs；Centre wavelength：1550nm.It is preferred that the repetition rate of laser is 100MHz, and centre wavelength 1550nm, femtosecond pulse
Line width for 100fs, frequency spectrum is 50nm；The grating length of side-hole fiber grating is 5mm；Wavelength-pressure-constant is 5nm/GPa.
B) the key technical indexes of 3 ports light rings is：1) line width：50nm-100nm；2) return loss ＞ 50dB；3)
Centre wavelength 1550nm.
C) the key technical indexes of side-hole fiber grating is：1) grating length：2mm-10mm；2) wavelength-pressure-constant is
1nm/GPa-10nm/GPa；3) centre wavelength 1550nm.
D) the key technical indexes of erbium-doped fiber amplifier is：1) gain：30dB-50dB；2) noise：＜ 2dB；3) center
Wavelength 1550nm.
E) the key technical indexes of raman amplifier is:1) gain：＞ 10dB；2) noise:＜ 1dB；3) centre wavelength
1550nm；4) service band：C-band.
F) the key technical indexes of optical fiber is:1) group velocity dispersion：17.4ps nm-1km-1 (centre wavelength 1550nm)；
2) group velocity：2.04 × 108m/s (centre wavelength 1550nm).
G) the key technical indexes of photodetector is：1) bandwidth：＞ 15GHz；2) gain：＞ 1000V/W；3 operating waves
Long range：800nm-1700nm.
H) the key technical indexes of digital oscilloscope is：1) bandwidth：＞ 12.5GHz；2 sample rates：＞ 50GS/s；3) it records
Length：＞ 10M Samples.
2, operation principle：When side-hole fiber grating of the shock wave in the present apparatus, each light pulse quilt of laser
It will be split into two " Gauss " pulses after side-hole fiber optical grating reflection, the frequency interval of two " Gaussian pulse " is acted on lateral opening
The modulation of surge on fiber grating.Shock wave is us magnitudes in the time of side-hole fiber grating, there is presently no
Infrared Transient spectral technique can get off the process record.Therefore, we introduce a kind of dispersion Fourier Transform Technique, by wink
State spectrum is converted to time-domain signal, then completes signal record by photodetector and digital oscilloscope.Finally, we are to showing
The time-domain signal of wave device record carries out data processing, frequency-region signal is obtained, to obtain surge.
Fig. 1 gives the structure diagram of side-hole fiber grating surge sensor.3 ends are passed through in each pulse of laser
The ports A of mouth optical circulator enter the side-hole fiber grating of the ports B and the effect that is hit.Light pulse is by side-hole fiber optical grating reflection
Afterwards, then from the ports B of 3 ports light rings enter C-terminal mouth, put in advance by erbium-doped fiber amplifier, preposition raman amplifier,
Dispersion Fourier transformation is carried out subsequently into single mode optical fiber, while light amplification is carried out by postposition raman amplifier.Finally, color is completed
The signal after Fourier transformation is dissipated by photodetector, oscillograph recording.
Fig. 2 gives the output optical pulse schematic diagram of laser, and Fig. 3 is the spectral schematic of laser.We select to swash
The repetition rate of light device is 100MHz, centre wavelength 1550nm, femtosecond pulse 100fs, and the line width of frequency spectrum is 50nm.
Fig. 4 is the reflectance spectrum figure of side-hole fiber grating, and the wavelength interval Δ λ between " Gauss " spectrum of two separation is only
It is related with surge Δ P, there is the relationship of formula (1)：
Δ λ=KP·ΔP (1)
In formula, KPFor wavelength-pressure-constant, there is substantial connection with the material of side-hole fiber grating, structure, what we selected
The wavelength of side-hole fiber grating-pressure-constant KPFor 5nm/GPa.
We select healthy and free from worry SMF-28e types single mode optical fiber as dispersive optical fiber, β1、β2With D in centre wavelength 1550nm
Value be respectively 5ns/m, 14.3ps2/km and -17.4ps/ (nmkm).
The time resolving power of side-hole fiber grating sensor is substantially determined that we select by the repetition rate of laser
Laser repetition rate be 100MHz, then the time resolving power of sensor be 10ns；Side-hole fiber grating sensor
Effective system bandwidth is mainly limited by the line width of repetition mode locking femto-second laser, erbium-based amplifier, and 30nm- is typically in the range of
The effective system bandwidth of 60nm, the side-hole fiber grating sensor that we select are about 50nm, due to wavelength-pressure of sensor
Constant is 5nm/GPa, then it can survey peak impact pressure and can reach 10GPa.
The process that chatted side-hole fiber grating surge sensor obtains surge is：
Step 21：The time-domain signal I (t) of oscillograph recording is that (cycle T is falling for the repetition rate of laser to periodic signal
Number) as shown in Figure 5.Time-domain signal I in i-th of periodi(t) corresponding frequency-region signal Ii(λ) is (in Fu of time-domain signal
Leaf transformation, and the similar spatial Fourier transform for meeting Fraunhofer diffraction condition), as shown in fig. 6, having identical shape
Formula, and the time t of time-domain signal and the wavelength X of frequency-region signal have the relationship of formula (2)：
Wherein, c is vacuum light speed；λ0For the centre wavelength of laser, λ is the non-central wavelength of laser, in
Near cardiac wave length；Z is fiber lengths；β1、β2Respectively it is the inverse and group velocity color of group velocity of the optical fiber under centre wavelength
It dissipates.β1About 5ns/m；Z is fiber lengths, β2For 14.3ps2/km
Step 22：If Ii(t)、IiThe interval of two separation " Gauss " pulses of (λ) is respectively Δ ti、Δλi, then they have
The relationship of formula (3).
In formula, D is dispersion parameter, and value is -17.4ps/ (nmkm)；Itself and group velocity dispersion β2Relationship：
Step 23：According to formula (1), by IiThe wavelength interval Δ λ of (λ)iDivided by wavelength-pressure-constant KP, so that it may it is somebody's turn to do
Pressure P in periodi。
Step 24:Using i-th of period of time-domain signal as abscissa, PiAs ordinate, then surge-can be made
Time graph.
Further, the step 22 includes：
Step 221：By Ii(t) t at the time of two separation " Gauss " peak value of pulses correspond toi1、ti2Bring the right side of formula (2) into
Side, and by Ii(λ) corresponding two peak wavelength λi1、λi2Bringing the left side of formula (2) into can obtain：
Step 222：The both sides of formula (5), formula (4) are subtracted each other, can be obtained
Formula (6) left side is deformed, can be obtained
Step 223：Formula (7) is brought into the left side of formula (6) to be obtained：
It enablesThen formula (8) is transformed to formula (3), obtains Δ λi：
The invention is not limited in specific implementation modes above-mentioned.The present invention, which expands to, any in the present specification to be disclosed
New feature or any new combination, and disclose any new method or process the step of or any new combination.
Claims (8)
1. a kind of fiber grating surge sensor, it is characterised in that including
Laser, for generating repetition femtosecond laser signal；
Three port circulators, for receiving the femto-second laser pulse letter that laser generates by three port circulator first ports
Number, and pass through three port circulator second port outputs；The light pulse exported from three port circulator second ports is by lateral opening light
After fine optical grating reflection, spectrum will be split into two narrow " Gauss " pulse；It is two narrow when side-hole fiber grating is by percussion
The wavelength interval Δ λ of " Gauss " shape pulse will change；It is annular from three ports by the light pulse after side-hole fiber optical grating reflection
Device second port inputs, and is exported from three port circulator third ports to amplification and dispersion element；
Then amplification and dispersion element carry out color for the light pulse of three port circulator third port outputs to be amplified
Fourier transformation is dissipated to be transformed to light pulse to carry out two level amplification after time-domain signal, finally by amplified time-domain signal export to
Signal processing apparatus；
Signal processing apparatus, the time-domain signal for receiving amplification and dispersion element output, and the light for passing through signal processing apparatus
Time-domain signal is converted to electric signal by electric transducer, then by the oscillograph recording electric signal of signal processing apparatus after, then into
Row data processing calculates shock wave pressure according to formula (1)：
Δ λ=KP·P (1)
Wavelength interval Δ λ between " Gauss shape " spectrum of two of which separation is only related with shock wave pressure P, KPFor wavelength-pressure
Force constant；
After the oscillograph recording electric signal of the signal processing apparatus, then data processing is carried out, shock wave is calculated according to formula (1)
The detailed process of pressure is：
Step 21：The time-domain signal I (t) of oscillograph recording is periodic signal, and cycle T is the repetition rate of femto-second laser
It is reciprocal；Time-domain signal I in i-th of periodi(t) corresponding frequency-region signal is Ii(λ), and the time t of time-domain signal with
The wavelength X of frequency-region signal has the relationship of formula (2)：
Wherein c is vacuum light speed；λ0For the centre wavelength of laser, λ is the non-central wavelength of laser, between centre wavelength
Near；Z is fiber lengths；β1、β2The respectively inverse and group velocity dispersion of group velocity of the optical fiber under centre wavelength；
Step 22：If Ii(t)、IiThe interval of two separation " Gauss " pulses of (λ) is respectively Δ ti、Δλi, then they have formula (3)
Relationship；
In formula, D is dispersion parameter, with group velocity dispersion β2Relationship：
Step 23：According to formula (1), by IiThe wavelength interval Δ λ of (λ)iDivided by wavelength-pressure-constant KP, so that it may obtain the period
Interior pressure Pi。
2. a kind of fiber grating surge sensor according to claim 1, it is characterised in that the amplification and dispersion
Unit includes preposition raman amplifier, the progress color for carrying out the erbium-doped fiber amplifier of signal amplification, amplifying for signal
Dissipate the optical fiber of Fourier transformation and the postposition raman amplifier for signal amplification.
3. a kind of fiber grating surge sensor according to claim 2, it is characterised in that the step 22 includes：
Step 221：By Ii(t) t at the time of two separation " Gauss " peak value of pulses correspond toi1、ti2Bring the right of formula (2) into, and
By Ii(λ) corresponding two peak wavelength λi1、λi2Bringing the left side of formula (2) into can obtain：
Step 222：The both sides of formula (5), formula (4) are subtracted each other, can be obtained
Formula (6) left side is deformed, can be obtained
Step 223：Formula (7) is brought into the left side of formula (6) to be obtained：
It enablesThen formula (8) is transformed to formula (3), obtains Δ λi：
4. a kind of fiber grating surge sensor according to one of claims 1 to 3, it is characterised in that the laser
It is 50MHZ~200MHz to think highly of complex frequency；Line width is 50nm~100nm；Mean power is 50mW~200mW；The rising of pulse
Time is 1ps~100fs；Centre wavelength is 1550nm.
5. a kind of fiber grating surge processing method, it is characterised in that including：
Step 1：The Femtosecond Optical Pulses of repetition are generated by laser；
Step 2：Three port circulators receive the femto-second laser pulse that laser generates by three port circulator first ports to be believed
Number, and pass through three port circulator second port outputs；The light pulse exported from three port circulator second ports is by lateral opening light
After fine optical grating reflection, spectrum will be split into two narrow " Gauss " pulse；It is two narrow when side-hole fiber grating is by percussion
The wavelength interval Δ λ of " Gauss " pulse will change；By the light pulse after side-hole fiber optical grating reflection from three port circulators
Second port inputs, and is exported from three port circulator third ports to amplification and dispersion element；
Step 3：It is used to the light pulse of three port circulator third port outputs being amplified by amplification and dispersion element, so
It carries out carrying out two level amplification after frequency-region signal is transformed to time-domain signal by dispersion Fourier transformation afterwards, finally by amplified time domain
Signal is exported to signal processing apparatus；
Step 4：The time-domain signal of amplification and dispersion element output is received by signal processing apparatus, and passes through signal processing apparatus
Photoelectric converter time-domain signal is converted into electric signal, then by the oscillograph recording electric signal of signal processing apparatus after,
Data processing is carried out again, and shock wave pressure is finally calculated according to formula (1)：
Δ λ=Kp·P (1)
Wavelength interval Δ λ between " Gauss " spectrum of two of which separation is only related with shock wave pressure P, KPFor wavelength-pressure
Constant；
After the oscillograph recording electric signal of the signal processing apparatus, then data processing is carried out, is finally calculated and rushed according to formula (1)
The detailed process of pressure of hammer wave is：
Step 21：The time-domain signal I (t) of oscillograph recording is periodic signal, and cycle T is the inverse of the repetition rate of laser；
Time-domain signal I in i-th of periodi(t) corresponding frequency-region signal Ii(λ) (Fourier transformation of time-domain signal, and it is similar
Meet the spatial Fourier transform of Fraunhofer diffraction condition), as shown in fig. 6, there is identical form, and time domain is believed
Number time t and the wavelength X of frequency-region signal have the relationships of formula (2)：
Wherein, c is vacuum light speed；λ0For the centre wavelength of laser, λ is the non-central wavelength of laser, between centre wavelength
Near；Z is fiber lengths；β1、β2Respectively it is the inverse and group velocity dispersion of group velocity of the optical fiber under centre wavelength；
Step 22：If Ii(t)、IiThe interval of two separation " Gauss " pulses of (λ) is respectively Δ ti、Δλi, then they have formula (3)
Relationship；
In formula, D is dispersion parameter, with group velocity dispersion β2Relationship：
Step 23：According to formula (1), by IiThe wavelength interval Δ λ of (λ)iDivided by wavelength-pressure-constant KP, so that it may obtain the period
Interior pressure Pi。
6. a kind of fiber grating surge processing method according to claim 5, it is characterised in that described to amplify and prolong
Slow unit includes preposition raman amplifier for carrying out the erbium-doped fiber amplifier of signal amplification, amplifying for signal, progress
The dispersive optical fiber of dispersion Fourier transformation and the postposition raman amplifier amplified for signal.
7. a kind of fiber grating surge processing method according to claim 5, it is characterised in that step 22 packet
It includes：
Step 221：By Ii(t) t at the time of two separation " Gauss " peak value of pulses correspond toi1、ti2Bring the right of formula (2) into, and
By Ii(λ) corresponding two peak wavelength λi1、λi2Bringing the left side of formula (2) into can obtain：
Step 222：The both sides of formula (5), formula (4) are subtracted each other, can be obtained
Formula (6) left side is deformed, can be obtained
Step 223：Formula (7) is brought into the left side of formula (6) to be obtained：
It enablesThen formula (8) is transformed to formula (3), obtains Δ λi：
8. a kind of fiber grating surge processing method according to one of claim 5 to 7, it is characterised in that described to swash
It is 50MHZ~200MHz that light, which thinks highly of complex frequency,；Line width is 50nm~100nm；Mean power is 50mW~200mW；Pulse it is upper
It is 1ps~100fs to rise the time；Centre wavelength is 1550nm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| CN110530565B (en) * | 2019-09-23 | 2021-04-13 | 中国工程物理研究院流体物理研究所 | Multi-path time measuring device and method based on optical fiber probe |
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| CN101144380A (en) * | 2007-08-28 | 2008-03-19 | 天津爱天光电子科技有限公司 | High sensitivity lateral opening optical fiber optical grating temperature pressure sensing detecting system unrelated with polarization |
| CN101793570A (en) * | 2009-10-21 | 2010-08-04 | 南京大学 | Sensing method of optical-fiber Bragg grating laser device |
| CN102322937A (en) * | 2011-08-15 | 2012-01-18 | 西北核技术研究所 | Impact wave travel time parameter measuring method and device |
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| US5361313A (en) * | 1993-05-11 | 1994-11-01 | Martin Marietta Corporation | Two-mode remote fiber optic sensor |
| CN1230253A (en) * | 1996-09-09 | 1999-09-29 | 蓝路研究公司 | Fiber optic grating transverse strain sensor system |
| CN1844856A (en) * | 2006-05-26 | 2006-10-11 | 北京交通大学 | Transverse stress sensing system and implementation method of photonic crystal fiber with grating written |
| CN101144380A (en) * | 2007-08-28 | 2008-03-19 | 天津爱天光电子科技有限公司 | High sensitivity lateral opening optical fiber optical grating temperature pressure sensing detecting system unrelated with polarization |
| CN101793570A (en) * | 2009-10-21 | 2010-08-04 | 南京大学 | Sensing method of optical-fiber Bragg grating laser device |
| CN102322937A (en) * | 2011-08-15 | 2012-01-18 | 西北核技术研究所 | Impact wave travel time parameter measuring method and device |
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