CN105424252A - Optical fiber grating shock pressure sensor and processing method - Google Patents

Abstract

The invention relates to the technical field of measurement, and particularly relates to an optical fiber grating shock pressure sensor and processing method. The invention aims to provide a side hole optical fiber grating sensor to measure shock pressure by aiming at the defects of a measurement method which measures phase difference by utilizing a ranging arm optical fiber Mach-Zehnder interference device to convert wavelength shift of the optical fiber gating caused by shock pressure into interference signals. Secondary amplification is performed on optical pulse signals outputted by the third port of a three-port circulator, and signal delay is performed simultaneously and then the optical pulse signals are outputted to a signal processing device; and the signal processing device receives the optical signals outputted by the amplification and delay port and the optical pulse signals are converted into electric signals by the photoelectric converter of the signal processing device, and then recording is performed by the signal processing device and an oscilloscope so that shock wave pressure is calculated by the processor of the signal processing device.

Description

A kind of fiber grating surge pressure sensor and disposal route

Technical field

The present invention relates to field of measuring technique, especially a kind of fiber grating surge pressure sensor and disposal route.

Background technology

In Shock wave physics, detonation physics field, accurately measure surge pressure to the equation of state of material and constitutive relation, containing can the burning-detonation conversion of explosive, high explosive Impact Initiation and detonation property, the impact phase transition of material and the research such as dynamic damage of material and fracture significant.Surge pressure in accurate measuring media has direct reference significance to conventional weapon designing technique, damage effect research and new material research.

Document < utilizes the surge pressure > (P.G.Van'tHof in fiber-optic grating sensor measurement explosive, L.K.Cheng, J.H.G.Schopltes, W.C.Prinse.DynamicPressureMeasurementofShockWavesinExplo sivesbyMeansofaFiberBraggGratingSensor, Proc.ofSPIEVol.6279, 62791Y, (2007) 0277-786/07.) report and utilized unequal arm optical fiber Mach-Zehnder interference device, surge pressure caused the wavelength of fiber grating to move and be converted to interference signal, thus the measuring method of detected phase difference.Document report survey peak impact pressure and be about 1GPa, system time resolving power is submicrosecond magnitude.This technology has the following disadvantages: 1) system time differentiates this for submicrosecond magnitude, is difficult to totally linearization, causes signal " distortion ", even " loss " to fast impact process; 2) need Accurate Calibration pressure-volume curve in advance, otherwise cannot surge pressure be calculated; 3) be difficult to accurately the optical path difference of unequal arm optical fiber Mach-Zehnder interference device be controlled at about 1 ± 0.1mm; 4) to survey the peak value of surge pressure too little, be about 1GPa.

Summary of the invention

Technical matters to be solved by this invention is: for utilizing unequal arm optical fiber Mach-Zehnder interference device, surge pressure caused the wavelength of fiber grating to move and be converted to interference signal, thus the shortcoming that the measuring method of detected phase difference exists, a kind of side-hole fiber grating sensor is proposed to measure surge pressure.Its concrete summary of the invention is as follows:

1) surge pressure caused the wavelength of fiber grating to move (transient state spectrum signal) and be converted to time-domain signal, then by photodetector and digital oscilloscope settling signal record;

2) adopt dispersion Fourier Transform Technique that time-domain signal is converted to transient state spectrum signal, thus acquisition surge pressure cause the wavelength of fiber grating to move.

The technical solution used in the present invention is as follows:

A kind of fiber grating surge pressure sensor comprises:

Laser instrument, for generation of repetition, Femtosecond Optical Pulses, as shown in Figure 2, its spectrum as shown in Figure 3 for its time domain waveform.

Three port circulators, for the femto-second laser pulse signal produced by three port circulator first port accepts laser instruments, and are exported by three port circulator second ports; From three port circulator second ports export light pulse by after side-hole fiber optical grating reflection, spectrum will be split into two narrow " Gauss " pulses; Its spectral shape as shown in Figure 4.When side-hole fiber grating is subject to percussive action, the wavelength interval Δ λ of two narrow " Gauss " shapes pulse will change; Inputted from three port circulator second ports by the light pulse after side-hole fiber optical grating reflection, export amplification and dispersion element to from three port circulator the 3rd ports;

Amplify and dispersion element, light pulse for being exported by three port circulator the 3rd ports is amplified, then carry out dispersion Fourier transform by light pulse be transformed to time-domain signal after carry out secondary amplification, finally by amplify after time-domain signal export signal processing apparatus to;

Signal processing apparatus, for receiving the time-domain signal of amplification and dispersion element output, and by the photoelectric commutator of signal processing apparatus, time-domain signal is converted to electric signal, then by after the oscillograph recording electric signal of signal processing apparatus, carry out data processing again, finally calculate shock wave pressure according to formula (1):

Δλ＝K _P·P(1)

Wavelength interval Δ λ wherein between two " Gauss's shape " spectrum be separated is only relevant with shock wave pressure P, K _pfor wavelength-pressure-constant, there is substantial connection with the material of side-hole fiber grating, structure.。

Further, described amplification and delay cell comprise Erbium-Doped Fiber Amplifier (EDFA), the preposition raman amplifier for signal amplification, the optical fiber carrying out dispersion Fourier transform and the rearmounted raman amplifier amplified for signal for carrying out signal amplification.

Further, after the oscillograph recording electric signal of described treating apparatus, then carry out data processing, the detailed process calculating shock wave pressure according to formula (1) is:

Step 21: time-domain signal I (t) of oscillograph recording is periodic signal, and its cycle T is the inverse of the repetition frequency of femto-second laser; Time-domain signal I in i-th cycle _it () frequency-region signal corresponding with it is I _i, and the wavelength X of the time t of time-domain signal and frequency-region signal has the relation of formula (2) (λ):

$2\mathrm{\&pi;}c(\frac{1}{\mathrm{\&lambda;}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(2\right)$

Wherein c is vacuum light speed; λ ₀for the centre wavelength of laser instrument, λ is the non-central wavelength of laser instrument, and it is near centre wavelength; Z is fiber lengths; β ₁, β ₂be respectively the Reciprocals sums GVD (Group Velocity Dispersion) for the group velocity of optical fiber under centre wavelength;

Step 22: establish I _i(t), I _i(λ) interval of two separation " Gauss " pulse is respectively Δ t _i, Δ λ _i, then they have the relation of formula (3).

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;z}---\left(3\right)$

In formula, D is dispersion parameter, itself and GVD (Group Velocity Dispersion) β ₂relation:

Step 23: according to formula (1), by I _i(λ) wavelength interval Δ λ _idivided by wavelength-pressure-constant K _p, just can obtain the pressure P in this cycle _i.

Further, described step 22 comprises:

Step 221: by I _it moment t that two separation " Gauss " peak value of pulses of () are corresponding _i1, t _i2bring the right of formula (2) into, and by I _i(λ) two corresponding with it peak wavelength λ _i1, λ _i2the left side bringing formula (2) into can obtain:

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i1}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i1}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(4\right)$

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i2}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(5\right)$

Step 222: the both sides of formula (5), formula (4) are subtracted each other, can obtain

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{12}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=\frac{t_{i2}-t_{i1}}{{\mathrm{\&beta;}}_{2}Z}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(6\right)$

Formula (6) left side is out of shape, can obtains

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=-2\mathrm{\&pi;}c\frac{({\mathrm{\&lambda;}}_{i2}-{\mathrm{\&lambda;}}_{i1})}{{\mathrm{\&lambda;}}_{i1}{\mathrm{\&lambda;}}_{i2}}\&ap;-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}---\left(7\right)$

Step 223: the left side that formula (7) brings formula (6) into can be obtained:

$-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}=\frac{{\mathrm{\&Delta;t}}_1}{{\mathrm{\&beta;}}_{2}Z}---\left(8\right)$

Order then formula (8) is transformed to formula (3), obtains Δ λ _i:

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;Z}---\left(3\right).$

Further, described laser instrument repetition frequency is 50MHZ ~ 200MHz; Live width is 50nm ~ 100nm; Average power is 50mW ~ 200mW; The rise time of pulse is 1ps ~ 100fs; Centre wavelength is 1550nm.

A kind of fiber grating surge pressure disposal route comprises:

Step 1: produce femtosecond laser signal by laser instrument;

Step 2: the femto-second laser pulse signal that three port circulators are produced by three port circulator first port accepts laser instruments, and exported by three port circulator second ports; From three port circulator second ports export light pulse by after side-hole fiber optical grating reflection, spectrum will be split into two narrow " Gauss " pulses, and its spectral shape is as shown in Figure 4.When side-hole fiber grating is subject to percussive action, the wavelength interval Δ λ of two narrow " Gauss " pulses will change; Inputted from three port circulator second ports by the light pulse after side-hole fiber optical grating reflection, export amplification and dispersion element to from three port circulator the 3rd ports;

Step 3: amplified by the light pulse of amplifying and delay cell is used for three port circulator the 3rd ports export, then carry out carrying out secondary amplification after frequency-region signal is transformed to time-domain signal by dispersion Fourier transform, finally export the time-domain signal after amplification to signal processing apparatus;

Step 4: the time-domain signal being received amplification and dispersion element output by signal processing apparatus, and by the photoelectric commutator of signal processing apparatus, time-domain signal is converted to electric signal, then by after the oscillograph recording electric signal of signal processing apparatus, carry out data processing again, finally calculate shock wave pressure according to formula (1):

Δλ＝K _p·P(1)

Wavelength interval Δ λ wherein between two " Gauss " spectrum be separated is only relevant with shock wave pressure P, K _pfor wavelength-pressure-constant.

Further, described amplification and delay cell comprise Erbium-Doped Fiber Amplifier (EDFA), the preposition raman amplifier for signal amplification, the dispersive optical fiber carrying out dispersion Fourier transform and the rearmounted raman amplifier amplified for signal for carrying out signal amplification.

Further, after the oscillograph recording electric signal of described signal processing apparatus, then carry out data processing, according to the detailed process of formula (1) calculating shock wave pressure be finally:

Step 21: time-domain signal I (t) of oscillograph recording is periodic signal, and its cycle T is the inverse of the repetition frequency of femto-second laser; Time-domain signal I in i-th cycle _it () frequency-region signal corresponding with it is I _i, and the wavelength X of the time t of time-domain signal and frequency-region signal has the relation of formula (2) (λ):

$2\mathrm{\&pi;}c(\frac{1}{\mathrm{\&lambda;}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(2\right)$

Wherein c is vacuum light speed; λ ₀for the centre wavelength of laser instrument, λ is the non-central wavelength of laser instrument, and it is near centre wavelength; Z is fiber lengths; β ₁, β ₂be respectively the Reciprocals sums GVD (Group Velocity Dispersion) for the group velocity of optical fiber under centre wavelength;

Step 22: establish I _i(t), I _i(λ) interval of two separation " Gauss " pulse is respectively Δ t _i, Δ λ _i, then they have the relation of formula (3).

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;z}---\left(3\right)$

In formula, D is dispersion parameter, itself and GVD (Group Velocity Dispersion) β ₂relation:

Step 23: according to formula (1), by I _i(λ) wavelength interval Δ λ _idivided by wavelength-pressure-constant K _p, just can obtain the pressure P in this cycle _i.

Further, described step 22 comprises:

Step 221: by I _it moment t that two separation " Gauss " peak value of pulses of () are corresponding _i1, t _i2bring the right of formula (2) into, and by I _i(λ) two corresponding with it peak wavelength λ _i1, λ _i2the left side bringing formula (2) into can obtain:

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i1}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i1}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(4\right)$

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i2}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(5\right)$

Step 222: the both sides of formula (5), formula (4) are subtracted each other, can obtain

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=\frac{t_{i2}-t_{i1}}{{\mathrm{\&beta;}}_{2}Z}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(6\right)$

Formula (6) left side is out of shape, can obtains

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=-2\mathrm{\&pi;}c\frac{({\mathrm{\&lambda;}}_{i2}-{\mathrm{\&lambda;}}_{i1})}{{\mathrm{\&lambda;}}_{i1}{\mathrm{\&lambda;}}_{i2}}\&ap;-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}---\left(7\right)$

Step 223: the left side that formula (7) brings formula (6) into can be obtained:

$-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(8\right)$

Order then formula (8) is transformed to formula (3), obtains Δ λ _i:

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;Z}---\left(3\right).$

Further, described laser instrument repetition frequency is 50MHZ ~ 200MHz; Live width is 50nm ~ 100nm; Average power is 50mW ~ 200mW; The rise time of pulse is 1ps ~ 100fs; Centre wavelength is 1550nm.

In sum, owing to have employed technique scheme, the invention has the beneficial effects as follows:

1) surge pressure surveyed of this sensor brings up to 10GPa ((can measuring pressure peak value be the pressure-wave-length constant of the live width/side-hole fiber grating of laser instrument) left and right, expands the measurement range of fiber bragg grating pressure sensor.

2) system response time can reach the 10ns inverse of laser instrument repetition frequency (system response time be) left and right, can respond impact process comparatively truly;

3) wavelength of the side-hole fiber grating of this sensor employing moves the only linear relation with surge pressure, and temperature independent, and therefore this sensor does not need nominal pressure-volume curve.

Accompanying drawing explanation

Examples of the present invention will be described by way of reference to the accompanying drawings, wherein:

Fig. 1 is the structured flowchart of side-hole fiber grating surge pressure sensor of the present invention.

Fig. 2 is the output optical pulse schematic diagram of laser instrument

Fig. 3 is the spectrum schematic diagram of laser instrument

Fig. 4 is the reflected light spectrogram of side-hole fiber grating.

Fig. 5 is the time-domain signal figure of oscillograph recording.

Fig. 6 is frequency domain signal diagrams.

Embodiment

All features disclosed in this instructions, or the step in disclosed all methods or process, except mutually exclusive feature and/or step, all can combine by any way.

Arbitrary feature disclosed in this instructions (comprising any accessory claim, summary and accompanying drawing), unless specifically stated otherwise, all can be replaced by other equivalences or the alternative features with similar object.That is, unless specifically stated otherwise, each feature is an example in a series of equivalence or similar characteristics.

Related description of the present invention:

1, the technical indicator of main components is as follows:

A) laser instrument in the present invention is repetition locked mode femto-second laser, and its important technological parameters is: 1) repetition frequency: 50MHZ-200MHz; 2) live width: 50nm-100nm; 3) average power: 50mW-200mW; 4) rise time of pulse: 50fs-1000fs; Centre wavelength: 1550nm.The repetition frequency of preferred laser is 100MHz, and centre wavelength is 1550nm, and femtosecond pulse is 100fs, and the live width of 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) live 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 (EDFA) is: 1) gain: 30dB-50dB; 2) noise: < 2dB; 3) centre 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) GVD (Group Velocity Dispersion): 17.4psnm-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 wavelength ranges: 800nm-1700nm.

H) the key technical indexes of digital oscilloscope is: 1) bandwidth: > 12.5GHz; 2 sampling rates: > 50GS/s; 3) record length: > 10MSamples.

2, principle of work: when the side-hole fiber grating of shock wave at this device, each light pulse of laser instrument will be split into two " Gauss " pulses after side-hole fiber optical grating reflection, the frequency interval of two " Gauss pulses " is subject to the modulation of the surge pressure acted on side-hole fiber grating.Shock wave is us magnitude in the time of side-hole fiber grating, does not also have Infrared Transient spectral technique this process record can be got off at present.Therefore, we introduce a kind of dispersion Fourier Transform Technique, and transient state spectrum is converted to time-domain signal, then by photodetector and digital oscilloscope settling signal record.Finally, we carry out data processing to the time-domain signal of oscillograph recording, obtain frequency-region signal, thus obtain surge pressure.

Fig. 1 gives the structured flowchart of side-hole fiber grating surge pressure sensor.Each pulse of laser instrument enters B port and the side-hole fiber grating of the effect of being hit through the A port of 3 ports light rings.Light pulse is by after side-hole fiber optical grating reflection, C port is entered again from the B port of 3 ports light rings, put in advance by Erbium-Doped Fiber Amplifier (EDFA), preposition raman amplifier, then enter single-mode fiber and carry out dispersion Fourier transform, carried out light amplification by rearmounted raman amplifier simultaneously.Finally, the signal after dispersion Fourier transform is completed by photodetector, oscillograph recording.

Fig. 2 gives the output optical pulse schematic diagram of laser instrument, and Fig. 3 is the spectrum schematic diagram of laser instrument.We select the repetition frequency of laser instrument to be 100MHz, and centre wavelength is 1550nm, and femtosecond pulse is 100fs, and the live width of frequency spectrum is 50nm.

Fig. 4 is the reflected light spectrogram of side-hole fiber grating, and the wavelength interval Δ λ between two " Gauss " spectrum be separated is only relevant with surge pressure Δ P, has the relation of formula (1):

Δλ＝K _P·ΔP(1)

In formula, K _pfor wavelength-pressure-constant, there is substantial connection with the material of side-hole fiber grating, structure, the wavelength-pressure-constant K of the side-hole fiber grating that we select _pfor 5nm/GPa.

We select healthy and free from worry SMF-28e type single-mode fiber as dispersive optical fiber, its β ₁, β ₂5ns/m, 14.3ps2/km and-17.4ps/ (nmkm) is respectively in the value of centre wavelength 1550nm with D.

The time resolving power of side-hole fiber grating sensor is determined by the repetition frequency of laser instrument substantially, and the repetition frequency of the laser instrument that we select is 100MHz, then the time resolving power of sensor is 10ns; The effective system bandwidth of side-hole fiber grating sensor is mainly subject to the restriction of live width of repetition locked mode femto-second laser, erbium-based amplifier, general between 30nm-60nm, the effective system bandwidth of the side-hole fiber grating sensor that we select is about 50nm, wavelength-pressure-constant due to sensor is 5nm/GPa, then it can be surveyed peak impact pressure and can reach 10GPa.

Chat side-hole fiber grating surge pressure sensor and obtain the process of surge pressure and be:

Step 21: time-domain signal I (t) of oscillograph recording for periodic signal (cycle T is the inverse of the repetition frequency of laser instrument) as shown in Figure 5.Time-domain signal I in i-th cycle _it frequency-region signal I that () is corresponding with it _i(λ) (the Fourier transform of time-domain signal, and the similar spatial fourier transform meeting Fraunhofer diffraction condition), as shown in Figure 6, there is identical form, and the wavelength X of the time t of time-domain signal and frequency-region signal there is the relation of formula (2):

$2\mathrm{\&pi;}c(\frac{1}{\mathrm{\&lambda;}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(2\right)$

Wherein, c is vacuum light speed; λ ₀for the centre wavelength of laser instrument, λ is the non-central wavelength of laser instrument, and it is near centre wavelength; Z is fiber lengths; β ₁, β ₂be respectively the Reciprocals sums GVD (Group Velocity Dispersion) for the group velocity of optical fiber under centre wavelength.β ₁be about 5ns/m; Z is fiber lengths, β ₂for 14.3ps2/km

Step 22: establish I _i(t), I _i(λ) interval of two separation " Gauss " pulse is respectively Δ t _i, Δ λ _i, then they have the relation of formula (3).

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;z}---\left(3\right)$

In formula, D is dispersion parameter, and its value is-17.4ps/ (nmkm); Itself and GVD (Group Velocity Dispersion) β ₂relation:

$D=-\frac{2\mathrm{\&pi;}c}{{\mathrm{\&lambda;}}_0^2}{\mathrm{\&beta;}}_2.$

Step 23: according to formula (1), by I _i(λ) wavelength interval Δ λ _idivided by wavelength-pressure-constant K _p, just can obtain the pressure P in this cycle _i.

Step 24: using i-th of time-domain signal cycle as horizontal ordinate, P _ias ordinate, then can make percussive pressure force-time curve.

Further, described step 22 comprises:

Step 221: by I _it moment t that two separation " Gauss " peak value of pulses of () are corresponding _i1, t _i2bring the right of formula (2) into, and by I _i(λ) two corresponding with it peak wavelength λ _i1, λ _i2the left side bringing formula (2) into can obtain:

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i1}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i1}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(4\right)$

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i2}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(5\right)$

Step 222: the both sides of formula (5), formula (4) are subtracted each other, can obtain

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=\frac{t_{i2}-t_{i1}}{{\mathrm{\&beta;}}_{2}Z}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(6\right)$

Formula (6) left side is out of shape, can obtains

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=-2\mathrm{\&pi;}c\frac{({\mathrm{\&lambda;}}_{i2}-{\mathrm{\&lambda;}}_{i1})}{{\mathrm{\&lambda;}}_{i1}{\mathrm{\&lambda;}}_{i2}}\&ap;-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}---\left(7\right)$

Step 223: the left side that formula (7) brings formula (6) into can be obtained:

$-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(8\right)$

Order then formula (8) is transformed to formula (3), obtains Δ λ _i:

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;Z}---\left(3\right)$

The present invention is not limited to aforesaid embodiment.The present invention expands to any new feature of disclosing in this manual or any combination newly, and the step of the arbitrary new method disclosed or process or any combination newly.

Claims (10)

1. a fiber grating surge pressure sensor, is characterized in that comprising

Laser instrument, for generation of repetition femtosecond laser signal;

Three port circulators, for the femto-second laser pulse signal produced by three port circulator first port accepts laser instruments, and are exported by three port circulator second ports; From three port circulator second ports export light pulse by after side-hole fiber optical grating reflection, spectrum will be split into two narrow " Gauss " pulses; When side-hole fiber grating is subject to percussive action, the wavelength interval Δ λ of two narrow " Gauss " shapes pulse will change; Inputted from three port circulator second ports by the light pulse after side-hole fiber optical grating reflection, export amplification and dispersion element to from three port circulator the 3rd ports;

Amplify and dispersion element, light pulse for being exported by three port circulator the 3rd ports is amplified, then carry out dispersion Fourier transform by light pulse be transformed to time-domain signal after carry out secondary amplification, finally by amplify after time-domain signal export signal processing apparatus to;

Signal processing apparatus, for receiving the time-domain signal of amplification and dispersion element output, and by the photoelectric commutator of signal processing apparatus, time-domain signal is converted to electric signal, then by after the oscillograph recording electric signal of signal processing apparatus, carry out data processing again, calculate shock wave pressure according to formula (1):

Δλ＝K _P·P(1)

Wavelength interval Δ λ wherein between two " Gauss's shape " spectrum be separated is only relevant with shock wave pressure P, K _pfor wavelength-pressure-constant.

2. a kind of fiber grating surge pressure sensor according to claim 1, is characterized in that described amplification and dispersion element comprise Erbium-Doped Fiber Amplifier (EDFA), the preposition raman amplifier for signal amplification, the optical fiber carrying out dispersion Fourier transform and the rearmounted raman amplifier amplified for signal for carrying out signal amplification.

3. a kind of fiber grating surge pressure sensor according to claim 2, after it is characterized in that the oscillograph recording electric signal of described number treating apparatus, then carry out data processing, the detailed process calculating shock wave pressure according to formula (1) is:

Step 21: time-domain signal I (t) of oscillograph recording is periodic signal, and its cycle T is the inverse of the repetition frequency of femto-second laser; Time-domain signal I in i-th cycle _it () frequency-region signal corresponding with it is I _i, and the wavelength X of the time t of time-domain signal and frequency-region signal has the relation of formula (2) (λ):

$2\mathrm{\&pi;}c(\frac{1}{\mathrm{\&lambda;}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(2\right)$

Wherein c is vacuum light speed; λ ₀for the centre wavelength of laser instrument, λ is the non-central wavelength of laser instrument, and it is near centre wavelength; Z is fiber lengths; β ₁, β ₂be respectively the Reciprocals sums GVD (Group Velocity Dispersion) of the group velocity of optical fiber under centre wavelength;

Step 22: establish I _i(t), I _i(λ) interval of two separation " Gauss " pulse is respectively Δ t _i, Δ λ _i, then they have the relation of formula (3);

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;z}---\left(3\right)$

In formula, D is dispersion parameter, itself and GVD (Group Velocity Dispersion) β ₂relation:

Step 23: according to formula (1), by I _i(λ) wavelength interval Δ λ _idivided by wavelength-pressure-constant K _p, just can obtain the pressure P in this cycle _i.

4. a kind of fiber grating surge pressure sensor according to claim 3, is characterized in that described step 22 comprises:

Step 221: by I _it moment t that two separation " Gauss " peak value of pulses of () are corresponding _i1, t _i2bring the right of formula (2) into, and by I _i(λ) two corresponding with it peak wavelength λ _i1, λ _i2the left side bringing formula (2) into can obtain:

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i1}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i1}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(4\right)$

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i2}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(5\right)$

Step 222: the both sides of formula (5), formula (4) are subtracted each other, can obtain

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=\frac{t_{i2}-t_{i1}}{{\mathrm{\&beta;}}_{2}Z}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(6\right)$

Formula (6) left side is out of shape, can obtains

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=-2\mathrm{\&pi;}c\frac{({\mathrm{\&lambda;}}_{i2}-{\mathrm{\&lambda;}}_{i1})}{{\mathrm{\&lambda;}}_{i1}{\mathrm{\&lambda;}}_{i2}}\&ap;-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}---\left(7\right)$

Step 223: the left side that formula (7) brings formula (6) into can be obtained:

$-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(8\right)$

Order then formula (8) is transformed to formula (3), obtains Δ λ _i:

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;Z}---\left(3\right).$

5., according to a kind of fiber grating surge pressure sensor one of Claims 1-4 Suo Shu, it is characterized in that described laser instrument repetition frequency is 50MHZ ~ 200MHz; Live width is 50nm ~ 100nm; Average power is 50mW ~ 200mW; The rise time of pulse is 1ps ~ 100fs; Centre wavelength is 1550nm.

6. a fiber grating surge pressure disposal route, is characterized in that comprising:

Step 1: the Femtosecond Optical Pulses being produced repetition by laser instrument;

Step 2: the femto-second laser pulse signal that three port circulators are produced by three port circulator first port accepts laser instruments, and exported by three port circulator second ports; From three port circulator second ports export light pulse by after side-hole fiber optical grating reflection, spectrum will be split into two narrow " Gauss " pulses; When side-hole fiber grating is subject to percussive action, the wavelength interval Δ λ of two narrow " Gauss " pulses will change; Inputted from three port circulator second ports by the light pulse after side-hole fiber optical grating reflection, export amplification and dispersion element to from three port circulator the 3rd ports;

Step 3: amplified by the light pulse of amplifying and delay cell is used for three port circulator the 3rd ports export, then carry out carrying out secondary amplification after frequency-region signal is transformed to time-domain signal by dispersion Fourier transform, finally export the time-domain signal after amplification to signal processing apparatus;

Step 4: the time-domain signal being received amplification and dispersion element output by signal processing apparatus, and by the photoelectric commutator of signal processing apparatus, time-domain signal is converted to electric signal, then by after the oscillograph recording electric signal of signal processing apparatus, carry out data processing again, finally calculate shock wave pressure according to formula (1):

Δλ＝K _p·P(1)

Wavelength interval Δ λ wherein between two " Gauss " spectrum be separated is only relevant with shock wave pressure P, K _pfor wavelength-pressure-constant.

7. a kind of fiber grating surge pressure sensor according to claim 6, is characterized in that described amplification and delay cell comprise Erbium-Doped Fiber Amplifier (EDFA), the preposition raman amplifier for signal amplification, the dispersive optical fiber carrying out dispersion Fourier transform and the rearmounted raman amplifier amplified for signal for carrying out signal amplification.

8. a kind of fiber grating surge pressure sensor according to claim 7, after it is characterized in that the oscillograph recording electric signal of described signal processing apparatus, carry out data processing again, according to the detailed process of formula (1) calculating shock wave pressure be finally:

Step 21: time-domain signal I (t) of oscillograph recording is periodic signal, and cycle T is the inverse of the repetition frequency of laser instrument; Time-domain signal I in i-th cycle _it frequency-region signal I that () is corresponding with it _i(λ) (the Fourier transform of time-domain signal, and the similar spatial fourier transform meeting Fraunhofer diffraction condition), as shown in Figure 6, there is identical form, and the wavelength X of the time t of time-domain signal and frequency-region signal there is the relation of formula (2):

$2\mathrm{\&pi;}c(\frac{1}{\mathrm{\&lambda;}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(2\right)$

Wherein, c is vacuum light speed; λ ₀for the centre wavelength of laser instrument, λ is the non-central wavelength of laser instrument, and it is near centre wavelength; Z is fiber lengths; β ₁, β ₂be respectively the Reciprocals sums GVD (Group Velocity Dispersion) for the group velocity of optical fiber under centre wavelength;

Step 22: establish I _i(t), I _i(λ) interval of two separation " Gauss " pulse is respectively Δ t _i, Δ λ _i, then they have the relation of formula (3);

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;z}---\left(3\right)$

In formula, D is dispersion parameter, itself and GVD (Group Velocity Dispersion) β ₂relation:

Step 23: according to formula (1), by I _i(λ) wavelength interval Δ λ _idivided by wavelength-pressure-constant K _p, just can obtain the pressure P in this cycle _i.

9. a kind of fiber grating surge pressure sensor according to claim 8, is characterized in that described step 22 comprises:

Step 221: by I _it moment t that two separation " Gauss " peak value of pulses of () are corresponding _i1, t _i2bring the right of formula (2) into, and by I _i(λ) two corresponding with it peak wavelength λ _i1, λ _i2the left side bringing formula (2) into can obtain:

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i1}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i1}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(4\right)$

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_0})=\frac{t_{i2}-{\mathrm{\&beta;}}_{1}Z}{{\mathrm{\&beta;}}_{2}Z}---\left(5\right)$

Step 222: the both sides of formula (5), formula (4) are subtracted each other, can obtain

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=\frac{t_{i2}-t_{i1}}{{\mathrm{\&beta;}}_{2}Z}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(6\right)$

Formula (6) left side is out of shape, can obtains

$2\mathrm{\&pi;}c(\frac{1}{{\mathrm{\&lambda;}}_{i2}}-\frac{1}{{\mathrm{\&lambda;}}_{i1}})=-2\mathrm{\&pi;}c\frac{({\mathrm{\&lambda;}}_{i2}-{\mathrm{\&lambda;}}_{i1})}{{\mathrm{\&lambda;}}_{i1}{\mathrm{\&lambda;}}_{i2}}\&ap;-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}---\left(7\right)$

Step 223: the left side that formula (7) brings formula (6) into can be obtained:

$-2\mathrm{\&pi;}c\frac{{\mathrm{\&Delta;\&lambda;}}_i}{{\mathrm{\&lambda;}}_0^2}=\frac{{\mathrm{\&Delta;t}}_i}{{\mathrm{\&beta;}}_{2}Z}---\left(8\right)$

Order then formula (8) is transformed to formula (3), obtains Δ λ _i:

${\mathrm{\&Delta;\&lambda;}}_i=\frac{{\mathrm{\&Delta;t}}_i}{D\&CenterDot;Z}---\left(3\right).$

10., according to a kind of fiber grating surge pressure sensor one of claim 6 to 9 Suo Shu, it is characterized in that described laser instrument repetition frequency is 50MHZ ~ 200MHz; Live width is 50nm ~ 100nm; Average power is 50mW ~ 200mW; The rise time of pulse is 1ps ~ 100fs; Centre wavelength is 1550nm.