CN116839758A - Optical fiber sensing demodulation system with high signal-to-noise ratio and high precision and implementation method thereof - Google Patents
Optical fiber sensing demodulation system with high signal-to-noise ratio and high precision and implementation method thereof Download PDFInfo
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Abstract
The invention relates to an optical fiber sensing demodulation system with high signal-to-noise ratio and high precision and an implementation method thereof. The device comprises an optical path demodulation unit, a photoelectric conversion circuit unit and a signal processing unit; the optical path demodulation unit comprises an optical fiber grating FBGA serving as a reference optical fiber grating, an optical fiber grating FBGB serving as a sensing optical fiber grating, an acousto-optic modulator AOM for modulating a light source into a pulse light, a first 3-port circulator for splitting the transmission light and the incident light of the optical fiber grating FBGA, and a second 3-port circulator for connecting the reflected light of the optical fiber grating FBGB into a photoelectric receiving sub-module ROSA; the photoelectric conversion circuit unit comprises a photoelectric receiving sub-module ROSA for converting the reflected light of the fiber bragg grating FBGB into a current signal, and the current signal is converted into a voltage signal through a series resistor; the signal processing unit comprises a phase-locked loop PLL for collecting voltage signals and an MCU for integrating display. The system has the advantages of strong noise immunity, high demodulation precision, simple structure, low cost, portability and the like, and avoids the use of a spectrometer, an optical power meter and a demodulator.
Description
Technical Field
The invention belongs to the field of optical fiber temperature sensors, and particularly relates to an optical fiber sensing demodulation system with high signal-to-noise ratio and high precision and an implementation method thereof.
Background
The fiber bragg grating (FiberBragg Gratin, FBG) sensor has the characteristics of being passive, strong in interference resistance, strong in corrosion resistance and the like, and is suitable for distributed measurement in the electricity-fear environments such as tunnels and pipe galleries. The signal demodulation is a core technology applied to the fiber grating sensor, and the traditional method is to demodulate wavelength shift caused by the influence of temperature on the refractive index in the optical signal transmission process, so that the optical fiber grating sensor has higher safety. However, the wavelength shift needs to be observed by a spectrometer, so that the system is large in size and high in cost, and practical popularization is limited. Many studies have proposed replacing wavelength demodulation with phase demodulation. The phase interference demodulation method utilizes the reference light and the sensing light to generate a certain phase difference after interference, and the light intensity of the interference light is detected by the photoelectric detector to obtain phase information, so that the phase interference demodulation method has the advantages of high sensitivity, strong anti-interference performance and the like. However, the interferometric phase demodulation method requires strict interferometric conditions and complex algorithms, and has the problems of small dynamic range, low demodulation speed, complex structure, difficult manufacture and the like, and is difficult to mass production. In comparison with the former two, the light intensity demodulation method converts the relative wavelength shift of the sensing light and the reference light into light intensity, and the demodulation is realized by measuring the light intensity change of the output spectrum, such as a Sagnac edge filtering method and an overlap spectrum power monitoring method. The Sagnac edge filtering method has the advantages of simple structure and lower manufacturing cost, but the principle is that interference filtering is adopted, and the stability of the system is still limited by interference conditions. The overlap spectrum power monitoring method is to realize demodulation by monitoring the power of the overlap spectrum of two paths of fiber gratings, the system is simple and easy to realize, but the traditional power monitoring is direct current signals, noise resistance is poor, the interference of a light source and a light path is easy to occur, and the demodulation precision is low. In order to improve noise resistance and accuracy, the sensor head needs to adopt a sensitization type fiber bragg grating, and the sensitization type fiber bragg grating has a special packaging structure, is high in price and low in flexibility, and is not suitable for bending or soaking in liquid.
Disclosure of Invention
The invention aims to solve the problems of high price, impractical performance, poor noise immunity and the like existing in the prior structure by using demodulation methods such as a spectrometer, an optical power meter, a direct current light intensity demodulation and the like, and provides a high-signal-to-noise-ratio high-precision optical fiber sensing demodulation system and an implementation method thereof.
In order to achieve the above purpose, the technical scheme of the invention is as follows: a high-signal-to-noise ratio high-precision optical fiber sensing demodulation system comprises an optical path demodulation unit, a photoelectric conversion circuit unit and a signal processing unit; the optical path demodulation unit monitors temperature change by utilizing the linear relation between the power and the wavelength offset of the reflection spectrums of the two FBGs; the photoelectric conversion circuit unit converts the output of the optical path demodulation unit into a voltage signal and transmits the voltage signal to the signal processing unit; the signal processing unit displays temperature monitoring conditions according to the voltage signals and based on the voltage-temperature relationship.
In an embodiment of the present invention, the optical path demodulation unit includes an optical fiber grating FBGA as a reference optical fiber grating, an optical fiber grating FBGB as a sensing optical fiber grating, an acousto-optic modulator AOM for modulating the light source into the pulse light, a first 3-port circulator for splitting the transmitted light and the incident light of the optical fiber grating FBGA, and a second 3-port circulator for switching the reflected light of the optical fiber grating FBGB into the ROSA of the optoelectronic receiving sub-module;
the photoelectric conversion circuit unit comprises a photoelectric receiving submodule ROSA used for converting reflected light of the fiber bragg grating FBGB into a current signal and converting the current signal into a voltage signal through a series resistor;
the signal processing unit comprises a phase-locked loop (PLL) for collecting voltage signals, an integrated display MCU and an upper computer which is connected with the MCU through wireless communication and used for displaying temperature condition information.
In an embodiment of the invention, one end of the AOM is connected with a broadband light source ASE, and the other end is connected with a port 1 of the first 3-port circulator; the 2 ports of the first 3-port circulator are connected with one end of the fiber bragg grating FBGA, and the 3 ports are connected with one end of the fiber bragg grating FBGB; the second 3-port circulator is connected with one end of the fiber bragg grating FBGA, the 2-port circulator is connected with one end of the fiber bragg grating FBGB, and the 3-port circulator is connected with one end of the photoelectric receiving sub-module ROSA; the other end of the fiber bragg grating FBGA is sleeved by a cap; the other end of the fiber bragg grating FBGB is sleeved by a cap; the other end of the optical receiving sub-module ROSA is connected with one end of a phase-locked loop PLL; the other end of the phase-locked loop PLL is connected with the MCU.
In an embodiment of the present invention, a continuous light source generated by a broadband light source ASE is modulated by an acousto-optic modulator AOM and becomes pulse light, and when an optical fiber grating FBGA and an optical fiber grating FBGB are in the same temperature environment on the premise of neglecting transmission loss, the light intensity reflected by the optical fiber grating FBGB is unchanged; when the fiber grating FBGB is affected by temperature, the reflected light intensity changes along with the temperature; the temperature condition monitoring can be realized by measuring the corresponding relation between the reflected light power and the temperature and calibrating the sensing relation; the light intensity is converted into an electric signal by the photoelectric receiving submodule ROSA, and the frequency of the electric signal is consistent with the frequency of pulse light modulation.
In one embodiment of the invention, the broadband light source ASE generates a light source with a central wavelength of 1540nm-1560nm and a power of 20 mW.
In one embodiment of the present invention, the pulsed light has a frequency of 10KHz.
In an embodiment of the present invention, the fiber grating FBGA and the fiber grating FBGB are chirped fiber gratings.
In an embodiment of the present invention, the bandwidths of the fiber bragg grating FBGA and the fiber bragg grating FBGB are both 10nm, the center wavelength of the fiber bragg grating FBGA is 1550nm, and the center wavelength of the fiber bragg grating FBGB is 1555nm.
In an embodiment of the present invention, the PLL is a two-phase PLL.
The invention also provides a realization method of the optical fiber sensing demodulation system based on the high signal-to-noise ratio and high precision, on the basis of overlapping spectrum power monitoring, a continuous light source is modulated into pulse light with a certain frequency through an optical path demodulation unit, the sensed light intensity is converted into a voltage electric signal through a photoelectric conversion circuit unit and then the signal intensity is detected by a phase-locked loop in a signal processing unit, the output of the phase-locked loop is direct current quantity irrelevant to the phase, the amplitude of a voltage signal to be detected can be demodulated at the output end of the phase-locked loop only by keeping the frequency of a reference signal and the pulse modulation consistent, and then the temperature monitoring condition can be displayed based on the voltage-temperature relation.
Compared with the prior art, the invention has the following beneficial effects: on the basis of overlapping spectrum power monitoring, the continuous light source is modulated into pulse light with a certain frequency, and the sensed light intensity is converted into a pulse signal by the photoelectric detector and then the signal intensity is detected by the phase-locked loop. The novel system provided by the advantage that the phase-locked loop can extract weak signals from noise has the advantages of strong noise resistance, wide dynamic range and high precision, and the common FBG is adopted as a sensing head, so that the cost is low and the flexibility is good. Meanwhile, the phase-locked loop used by the system adopts a double-phase-locked structure, the output is a direct current quantity irrelevant to the phase, and the amplitude of the signal to be detected can be demodulated at the output end only by keeping the frequency of the reference signal as same as that of the pulse light source. Monitoring power changes is more direct and efficient than demodulation methods based on wavelength scanning and phase detection. Compared with the Sagnac light intensity demodulation method, the phase-locked loop-based detection mode has the advantages of high signal-to-noise ratio, high precision, good stability and the like. The system avoids the use of a spectrometer, an optical power meter and a demodulator, and has the advantages of simple and visual structure, low cost, portability and the like.
Drawings
Fig. 1 is a schematic diagram of a system according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating the reflectance spectrum and temperature variation according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of phase-locked loop weak signal extraction according to an embodiment of the invention.
Fig. 4 is a phase-locked voltage-temperature characteristic curve according to an embodiment of the invention.
Fig. 5 is a diagram illustrating comparison of signal to noise ratios of a system according to an embodiment of the present invention.
Fig. 6 is a graph of the demodulation result of the present invention.
Fig. 7 is a graph of real-time tracking of the actual temperature of the system.
Detailed Description
The technical scheme of the invention is specifically described below with reference to the accompanying drawings. In order to make the features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below:
as shown in fig. 1, the present invention provides a high signal-to-noise ratio and high precision optical fiber sensing demodulation system, which comprises: an optical path demodulation unit, a photoelectric conversion circuit unit, and a signal processing unit. The optical path demodulation unit comprises two paths of fiber gratings FBGA and FBGB, an acousto-optic modulator AOM and 2 3-port circulators, and the temperature change is monitored by utilizing the linear relation between the power and the wavelength offset of the reflection spectrums of the two FBGs; the photoelectric conversion circuit unit is connected with a resistor in series by a ROSA (optical signal processing) of the photoelectric receiving sub-module to realize current-voltage conversion. The signal processing unit comprises a double-phase-locked PLL and an integrated display MCU, the phase-locked voltage is transmitted to the upper computer in a wireless mode, and the upper computer displays the temperature condition according to the calibrated voltage-temperature relationship.
In this embodiment, the broadband light source ASE is used to generate a light source with a center wavelength of 1540nm-1560nm and a power of 20 mW;
in this embodiment, the acousto-optic modulator is used to modulate the continuous light source into a pulse light of 10KHz, one end is connected with ASE, and the other end is connected with the 3-port circulator 1.
In this embodiment, the 3-port circulator 1 is used for splitting the transmitted light and the incident light of the chirped fiber grating FBGA, and the 1-port circulator is connected to the AOM, the 2-port circulator is connected to the chirped fiber grating FBGA, and the 3-port circulator is connected to the chirped fiber grating FBGB.
In this embodiment, the 3-port circulator 2 is used to couple reflected light of the FBGB into the ROSA. The port 1 of the 3-port circulator 2 is connected with the FBGA, the port 2 is connected with the chirped fiber grating FBGB, and the port 3 is connected with the ROSA.
In this embodiment, the chirped fiber grating FBGA is used as a reference fiber grating, one end is connected to the 2 port of the 3-port circulator 1, and the other end is sleeved by a cap and is not connected in the air.
The chirped fiber grating FBGB is used as a sensing fiber grating, one end of the chirped fiber grating FBGB is connected with the 2 port of the 3-port circulator 2, and the other end of the chirped fiber grating FBGB is sleeved by a cap and is not connected in the air.
In this embodiment, the ROSA is configured to convert the reflected light of the FBGB into a current signal, and after being connected in series with a resistor, the ROSA is converted into a voltage signal for the PLL to collect. One end is connected with the 3 port of the 3-port circulator 2, and the other end is connected with a phase-locked loop PLL.
In this embodiment, the PLL is configured to lock and extract a 10KHz signal, so as to effectively suppress the photoelectric noise and improve the signal-to-noise ratio of the system. The phase-locked loop PLL is a two-phase-locked loop, and has a signal source and a multiplication filter built in. The signal source is used to generate a reference signal and another reference signal with a 90 degree phase offset, the frequency of which can be set. The multiplying filter is used for multiplying and filtering the two paths of reference signals with the input signals respectively to obtain direct current signals. One end of the PLL is connected with the ROSA, the other end of the PLL is connected with the MCU, and a display module is integrated in the MCU.
In this embodiment, the MCU transmits the phase-locked output voltage to the upper computer in a wireless manner.
In this embodiment, the upper computer displays a temperature monitoring condition according to the voltage-temperature relationship calibrated by the experiment.
In this embodiment, the light source is AOM modulated to reach 2 ports from 1 port of the circulator 1, 2 ports are connected to the FBGA, and 3 ports of the circulator 1 are connected to 1 port of the circulator 2. The optical signal is reflected by the FBGA and then enters the FBGB through the 2 ports of the circulator 2, and the reflected light of the FBGB enters the ROSA through the 3 ports of the circulator 2. The ROSA converts the converted current into voltage through serial current and then provides the voltage to the phase-locked loop. When the FBGA and the FBGB are in the same temperature environment, the reflection spectrum of the FBGB is unchanged. When the FBGA is in a certain fixed temperature state and the FBGB is affected by temperature, the center wavelength of the FBGB is shifted (in the long wave or short wave direction). Fig. 2 is a schematic diagram of a reflection spectrum in which FBGA is used as a reference fiber grating and FBGB is used as a sensing fiber grating. The center wavelength shifts in the long-wavelength direction due to the positive temperature characteristic of the fiber grating wavelength shift. When the center wavelength of the FBGB is larger than that of the FBGA, the overlap spectrum becomes small as shown in fig. 2 (b); conversely, the overlap spectrum becomes large, as shown in fig. 2 (c).
Assuming that the bandwidth of the FBGB is B T The wavelength shift amount caused by the influence of temperature is delta lambda B The reflection spectrum width of the FBGA and the FBGB isOr +.>Wavelength offset Δλ B Corresponding optical power variation delta P T For the sum of the optical powers P (lambda) corresponding to the wavelengths lambda of the points within the offset, i.e
Wherein k=a 1 P I B I ，a I Is the loss factor of the three-port circulator, P I Is the total power incident on the FBGB, B I Is the bandwidth of the incident light. When the bandwidth and power of the incident light are constant, k is constant, so the change in optical power is proportional to the shift in wavelength. Since the wavelength shift of the fiber bragg grating is proportional to the temperature, the change of the optical power is proportional to the temperature, and the temperature can be calibrated by measuring the optical power value.
The sensing signal is a weak signal which is submerged in noise under the influence of the circulator and the photoelectric detector, and the phase-locked amplifier can extract the weak signal from the noise and accurately measure the weak signal. The conventional Phase-locked loop is based on a Phase Sensitive Detection (PSD) (Phase-Sensitive Detection) which uses a reference signal having the same frequency and a fixed Phase relation with a signal to be measured as a reference, extracts a signal component related to the reference signal, and filters out noise components other than the reference frequency. The system uses a dual-phase-locked loop, outputs a direct current signal irrelevant to the phase of the signal, and the reference signal only needs to be consistent with the frequency of the signal to be detected without synchronization, so that the schematic diagram is shown in fig. 3.
The optical signal in the system is pulse type, and the signal obtained after photoelectric conversion is pulse type. Assuming that the pulse signal is Fourier decomposed intoWherein A is I 、w、/>The amplitude, frequency and phase of the input signal, respectively. The two paths of reference signals are S respectively R1 (t)＝A R sin (wt+delta) and S R2 (t)＝A R cos (wt+delta), wherein A R W, delta are the amplitude, frequency and phase of the reference signal, respectively. The input signal and the two paths of reference signals respectively enter a multiplier to obtain S psd1 (t) and S psd2 (t) then
S psd1 (t) and S psd2 (t) obtaining S after each pass through a low pass filter LPF1 (t) and S LPF2 (t)：
For S LPF1 (t) and S LPF2 (t) squaring and then squaring to obtain S out (t)：
From this, S out And (t) is a direct current signal which is independent of the frequency and phase of the signal, and the reference signal only needs to be consistent with the frequency of the signal to be detected, and does not need to be synchronized. Setting the amplitude of the reference signal to be 1V, and multiplying the acquired data during data processingThe amplitude of the signal to be measured can be obtained.
In this embodiment, a physical test setup test is performed according to the schematic diagram of fig. 1. In the experiment, a mode of heating the constant-temperature water tank in a water bath is adopted. The temperature is continuously heated to 90 ℃ from 10 ℃, sampling is carried out every 5s, and the temperature in the water tank and the phase-locked voltage are synchronously transmitted to the upper computer in real time by using a standard electronic temperature sensor. In experiments, a signal source was used to generate a pulse signal and a reference signal. We set a pulse signal of 10kHz with a duty cycle of 50% as the modulation signal and set the amplitude of the reference signal to 1V. The phase-locked sampled voltage versus temperature is shown in fig. 4. From fig. 4 it can be seen that the linear fits of the heating process and the cooling process are very close, so we only show the linear fit of the heating process in fig. 4. Wherein the R square of the linear fitness is about 0.99935, and the Temperature Coefficient (TC) of the proposed sensor is 0.796 mV/. Degree.C.
When the voltage temperature coefficient is so small, it is difficult to accurately identify the sampling voltage from noise. A temperature sensitive fiber bragg grating may be required as a sensor head. However, the cost, flexibility and temperature range of the system are limited by its particular packaging configuration. In this system, when the sensor head is a plain fiber grating, we use a PLL to extract the sampled voltage from the noise. The anti-noise performance of the system is verified through a comparison experiment with a direct current light intensity signal demodulation system. The results are shown in fig. 5, where fig. 5 (a) shows the noise as a function of temperature, and fig. 5 (b) shows the signal-to-noise ratio as a function of temperature. As shown in FIG. 5 (a), the middle line represents the modified system, the maximum noise value is 0.11mV, and the line with large fluctuation in the up-down direction represents the previous system, and the maximum noise value is 0.0188V. It can be seen that the PLL suppresses the noise of the proposed system greatly.
In this embodiment, the MCU sends the data to the PC remote monitoring terminal. Fig. 6 shows the measured temperature of the system. The temperature is measured continuously in the range of 10 ℃ to 90 ℃, including heating and cooling. As shown in fig. 6, the heating process and the cooling process are substantially identical, so we only show the linear fitting data of the heating process in fig. 6. The R square of the linear fitness is 0.99985 and the slope is 1.00187. The maximum standard deviation of the test temperature value is about 0.4981 ℃ when the test temperature value is close to the set temperature, which shows that the sensor has higher precision. Fig. 7 shows a real-time tracking graph of the actual temperature of the system, and it can be seen that the demodulation temperature can track the set temperature with high accuracy and low noise.
The above is a preferred embodiment of the present invention, and all changes made according to the technical solution of the present invention belong to the protection scope of the present invention when the generated functional effects do not exceed the scope of the technical solution of the present invention.
Claims (10)
1. The optical fiber sensing demodulation system with high signal-to-noise ratio and high precision is characterized by comprising an optical path demodulation unit, a photoelectric conversion circuit unit and a signal processing unit; the optical path demodulation unit monitors temperature change by utilizing the linear relation between the power and the wavelength offset of the reflection spectrums of the two FBGs; the photoelectric conversion circuit unit converts the output of the optical path demodulation unit into a voltage signal and transmits the voltage signal to the signal processing unit; the signal processing unit displays temperature monitoring conditions according to the voltage signals and based on the voltage-temperature relationship.
2. The high signal-to-noise ratio high accuracy fiber optic sensing demodulation system of claim 1 wherein,
the optical path demodulation unit comprises an optical fiber grating FBGA serving as a reference optical fiber grating, an optical fiber grating FBGB serving as a sensing optical fiber grating, an acousto-optic modulator AOM for modulating a light source into a pulse light, a first 3-port circulator for splitting the transmission light and the incident light of the optical fiber grating FBGA, and a second 3-port circulator for connecting the reflected light of the optical fiber grating FBGB into a photoelectric receiving sub-module ROSA;
the photoelectric conversion circuit unit comprises a photoelectric receiving submodule ROSA used for converting reflected light of the fiber bragg grating FBGB into a current signal and converting the current signal into a voltage signal through a series resistor;
the signal processing unit comprises a phase-locked loop (PLL) for collecting voltage signals, an integrated display MCU and an upper computer which is connected with the MCU through wireless communication and used for displaying temperature condition information.
3. The high signal-to-noise ratio high precision optical fiber sensing demodulation system according to claim 2, wherein one end of the acousto-optic modulator AOM is connected with a broadband light source ASE, and the other end is connected with a 1 port of a first 3-port circulator; the 2 ports of the first 3-port circulator are connected with one end of the fiber bragg grating FBGA, and the 3 ports are connected with one end of the fiber bragg grating FBGB; the second 3-port circulator is connected with one end of the fiber bragg grating FBGA, the 2-port circulator is connected with one end of the fiber bragg grating FBGB, and the 3-port circulator is connected with one end of the photoelectric receiving sub-module ROSA; the other end of the fiber bragg grating FBGA is sleeved by a cap; the other end of the fiber bragg grating FBGB is sleeved by a cap; the other end of the optical receiving sub-module ROSA is connected with one end of a phase-locked loop PLL; the other end of the phase-locked loop PLL is connected with the MCU.
4. The optical fiber sensing demodulation system with high signal to noise ratio and high precision according to claim 3, wherein continuous light source generated by broadband light source ASE is changed into pulse light after modulation of an acousto-optic modulator AOM, and under the premise of neglecting transmission loss, when the optical fiber grating FBGA and the optical fiber grating FBGB are in the same temperature environment, the light intensity reflected by the optical fiber grating FBGB is unchanged; when the fiber grating FBGB is affected by temperature, the reflected light intensity changes along with the temperature; the temperature condition monitoring can be realized by measuring the corresponding relation between the reflected light power and the temperature and calibrating the sensing relation; the light intensity is converted into an electric signal by the photoelectric receiving submodule ROSA, and the frequency of the electric signal is consistent with the frequency of pulse light modulation.
5. The high signal to noise ratio high precision optical fiber sensing demodulation system according to claim 2 wherein the broadband light source ASE generates a light source with a center wavelength of 1540nm-1560nm and a power of 20 mW.
6. The high signal-to-noise ratio high accuracy fiber optic sensing demodulation system of claim 2 wherein the pulsed light frequency is 10KHz.
7. The high signal-to-noise ratio high precision optical fiber sensing demodulation system according to claim 2, wherein the optical fiber grating FBGA and the optical fiber grating FBGB are both chirped optical fiber gratings.
8. The optical fiber sensing demodulation system with high signal to noise ratio and high precision according to claim 2, wherein the bandwidths of the optical fiber grating FBGA and the optical fiber grating FBGB are 10nm, the center wavelength of the optical fiber grating FBGA is 1550nm, and the center wavelength of the optical fiber grating FBGB is 1555nm.
9. The high signal-to-noise ratio high accuracy optical fiber sensing demodulation system of claim 2 wherein the phase-locked loop PLL is a two-phase-locked PLL loop.
10. The method for realizing the optical fiber sensing demodulation system with high signal-to-noise ratio and high precision based on any one of claims 1-9 is characterized in that on the basis of overlapping spectrum power monitoring, a continuous light source is modulated into pulse light with a certain frequency through an optical path demodulation unit, the sensed light intensity is converted into a voltage electric signal through a photoelectric conversion circuit unit and then is detected into signal intensity by a phase-locked loop in a signal processing unit, the output of the phase-locked loop is direct current quantity irrelevant to phase, the amplitude of a voltage signal to be detected can be demodulated at the output end of the phase-locked loop only by keeping the frequency of a reference signal and the pulse modulation consistent, and then the temperature monitoring condition can be displayed based on the voltage-temperature relation.
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| CN117109646A (en) * | 2023-10-25 | 2023-11-24 | 杭州奕力科技有限公司 | Sensing demodulation method of linear chirped fiber grating |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117109646A (en) * | 2023-10-25 | 2023-11-24 | 杭州奕力科技有限公司 | Sensing demodulation method of linear chirped fiber grating |
| CN117109646B (en) * | 2023-10-25 | 2024-02-23 | 杭州奕力科技有限公司 | Sensing demodulation method of linear chirped fiber grating |
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