Fiber optic sensor and measurement method, apparatus and storage medium

1 . A fiber optic sensor, at least comprising: a light source, a vector network analyzer, an electro-optic intensity modulator, a fiber optic containing a weak reflection grating array, a fiber optic amplifier, a fiber optic coupler, a dispersion compensator, a demodulator;

wherein, the electro-optic intensity modulator, coupled to the light source, the vector network analyzer, and the fiber optic containing the weak reflection grating array, is configured to:

modulate a microwave signal generated by the vector network analyzer into an optical signal generated by the light source, and

input a modulated optical signal into the fiber optic containing the weak reflection grating array;

the fiber optic amplifier, coupled to the fiber optic containing the weak reflection grating array and the fiber optic coupler, is configured to:

receive a reflected signal output by the fiber optic containing the weak reflection grating array, and

input an amplified reflected signal into the fiber optic coupler;

the fiber optic coupler, coupled to the fiber optic amplifier, the dispersion compensator, and the demodulator, is configured to:

split the amplified reflected signal, input an obtained first split signal into the dispersion compensator, and input an obtained second split signal into the demodulator;

the dispersion compensator, coupled to the fiber optic coupler and the demodulator, is configured to:

perform dispersion compensation on the first split signal, and

input a dispersion-compensated first split signal into the demodulator;

the demodulator, coupled to the fiber optic coupler and the dispersion compensator, is configured to:

demodulate a received signal to obtain each sub-signal of the second split signal and each sub-signal of the dispersion-compensated first split signal;

according to a historical second split signal and a dispersion-compensated historical first split signal determined at a historical measurement moment, and the second split signal and the dispersion-compensated first split signal determined at a current moment, determine a change delay for each sub-signal in the dispersion-compensated first split signal and a change delay for each sub-signal in the second split signal at the current moment; and

for each of the sub-signals, according to a change delay for the sub-signal, determine change amounts at a grating corresponding to the sub-signal and at a fiber optic segment connected with the grating.

2 . The fiber optic sensor according to claim 1 , wherein the fiber optic coupler comprises a first fiber optic coupler and a second fiber optic coupler;

the first fiber optic coupler, coupled to the fiber optic amplifier, the dispersion compensator, and the second fiber optic coupler, is configured to:

split the amplified reflected signal which is amplified by the fiber optic amplifier,

input the obtained first split signal into the dispersion compensator, and

input the obtained second split signal into the second fiber optic coupler;

the dispersion compensator, coupled to the first fiber optic coupler and the second fiber optic coupler, is configured to input the dispersion-compensated first split signal into the second fiber optic coupler;

the second fiber optic coupler, coupled to the first fiber optic coupler, the dispersion compensator, and the demodulator, is configured to:

couple the dispersion-compensated first split signal and the second split signal, to obtain a signal to be measured, and

input the signal to be measured into the demodulator.

3 . The fiber optic sensor according to claim 2 , further comprising an optical amplifier coupled to the second fiber optic coupler and the demodulator;

the optical amplifier is configured to:

receive the signal to be measured output by the second fiber optic coupler,

amplify the signal to be measured, and

input an amplified signal to be measured into the demodulator.

4 . The fiber optic sensor according to claim 1 , further comprising a fiber optic circulator, wherein an input end of the fiber optic circulator is coupled to an output end of the electro-optic intensity modulator, an input/output end of the fiber optic circulator is coupled to the fiber optic containing the weak reflection grating array, and an output end of the fiber optic circulator is coupled to the fiber optic amplifier.

5 . The fiber optic sensor according to claim 1 , further comprising a photodetector;

an input end of the photodetector is coupled to an output end of the fiber optic coupler and an output end of the dispersion compensator, an output end of the photodetector is coupled to an input end of the demodulator, the photodetector is configured to:

obtain a first electrical signal corresponding to the dispersion-compensated first split signal,

obtain a second electrical signal corresponding to the second split signal, and

input the first electrical signal and the second electrical signal into the demodulator;

the demodulator is further configured to:

determine a historical first electrical signal determined at the historical measurement moment as the dispersion-compensated historical first split signal,

determine a historical second electrical signal determined at the historical measurement moment as the historical second split signal,

determine the first electrical signal determined at the current moment as the dispersion-compensated first split signal, and

determine the second electrical signal determined at the current moment as the second split signal.

6 . The fiber optic sensor according to claim 1 , further comprising a fiber optic polarizer coupled to the light source, and a fiber optic polarization controller coupled to the fiber optic polarizer and the electro-optic intensity modulator;

wherein the fiber optic polarizer and the fiber optic polarization controller are configured to perform polarization control on the optical signal generated by the light source.

7 . The fiber optic sensor according to claim 1 , wherein the fiber optic containing the weak reflection grating array comprises a target fiber optic connected with an object to be measured and a reference fiber optic floatingly connected with the object to be measured; wherein,

the demodulator is further configured to:

according to a received second split signal and a dispersion-compensated first split signal corresponding to the reference fiber optic, determine change amounts at each grating and at each fiber optic segment between gratings in the reference fiber optic, to obtain a first change amount;

according to a received second split signal and a dispersion-compensated first split signal corresponding to the target fiber optic, determine change amounts at each grating and at each fiber optic segment between gratings in the target fiber optic, to obtain a second change amount; and

according to the first change amount and the second change amount, determine a change amount of the object to be measured.

8 . The fiber optic sensor according to claim 1 , wherein the demodulator is configured to:

determine a dispersion compensation function corresponding to the dispersion compensator;

for each of the sub-signals in the dispersion-compensated first split signal, according to the determined change delay of the signal and the dispersion compensation function, determine a change amount of a center wavelength of the grating corresponding to the sub-signal; and

according to the change amount of the center wavelength and physical properties of the fiber optic containing the weak reflection grating array, determine the change amount at the grating corresponding to the sub-signal;

wherein, the physical properties at least comprise an elastic-optic effect coefficient and a thermo-optic effect coefficient.

9 . The fiber optic sensor according to claim 8 , wherein a dispersion delay introduced by the dispersion compensator to perform dispersion comprises a change delay and a historical delay;

the demodulator is further configured to:

according to the dispersion-compensated first split signal, determine dispersion delays of sub-signals respectively corresponding to gratings in the fiber optic containing the weak reflection grating array;

according to the dispersion-compensated historical first split signal, determine historical delays of the sub-signals respectively corresponding to the gratings in the fiber optic containing the weak reflection grating array; and

for each of the gratings, according to the historical delay and the dispersion delay of the sub-signal corresponding to the grating, determine a change delay of the sub-signal corresponding to the grating.

10 . The fiber optic sensor according to claim 9 , wherein the demodulator is further configured to:

for each of the gratings in the fiber optic containing the weakly reflective-weak reflection grating array, according to the dispersion-compensated first split signal, determine a third delay of the sub-signal corresponding to the grating at the current moment, and a fourth delay of a sub-signal corresponding to an adjacent grating of the grating; and

according to the third delay and the fourth delay determined at the current moment, and a historical third delay and a historical fourth delay determined according to the dispersion-compensated historical first split signal, determine the change delay.

11 . The fiber optic sensor according to claim 1 , wherein the demodulator is further configured to:

for every two adjacent sub-signals of the second split signal, determine delays when the two sub-signals are transmitted along the fiber optic containing the weak reflection grating array, respectively as a first delay and a second delay determined at the current moment;

according to the first delay and the second delay, and a historical first delay and a historical second delay determined according to the historical second split signal, determine an optical path delay;

according to the optical path delay, determine a change amount of an optical path difference of the fiber optic segment between the two adjacent gratings corresponding to the two sub-signals; and

according to the change amount of the optical path difference and physical properties of the fiber optic containing the weak reflection grating array, determine a change amount at the fiber optic segment between the two adjacent gratings;

wherein, the physical properties at least comprise an elastic-optic effect coefficient, a thermo-optic effect coefficient, an effective refractive index, and a physical length of the fiber optic segment between the two adjacent gratings.

12 . The fiber optic sensor according to claim 1 , wherein the change amount comprises at least one of a temperature change amount or a deformation amount.

13 . A measurement method, wherein the measurement method is applied to a fiber optic sensor, the fiber optic sensor at least comprises following components: a light source, a vector network analyzer, an electro-optic intensity modulator, a fiber optic containing a weak reflection grating array, a fiber optic amplifier, a fiber optic coupler, a dispersion compensator, a demodulator;

the method comprises:

inputting a modulated optical signal into the fiber optic containing the weak reflection grating array, wherein the modulated optical signal is generated according to an optical signal generated by the light source and a microwave signal generated by the vector network analyzer;

splitting a reflected signal generated by the fiber optic containing the weak reflection grating array to obtain a first split signal and a second split signal, and performing dispersion compensation on the first split signal to obtain a dispersion-compensated first split signal;

according to a historical second split signal and a dispersion-compensated historical first split signal determined at a historical measurement moment, and the second split signal and the dispersion-compensated first split signal determined at a current moment, determining a change delay for each sub-signal in the dispersion-compensated first split signal and a change delay for each sub-signal in the second split signal at the current moment; and

for each of the sub-signals, according to a change delay for the sub-signal, determining a change amount at a grating corresponding to the sub-signal and a change amount at a fiber optic segment connected with the grating.