A multicore optical fiber distributed sensing system and a measurement method

Abstract

The application provides a kind of multicore optical fiber distributed sensing system and measurement method, and the multicore optical fiber distributed sensing system includes laser, circulator and optical fiber loop structure, laser is connected with the first port of circulator, and the second port of optical fiber loop structure is connected with circulator;It also includes optical wavelength division multiplexer, first optical detector and second optical detector, the multiplexing port of optical wavelength division multiplexer is connected with the third port of circulator, and the two distribution ports of optical wavelength division multiplexer are connected with first optical detector and second optical detector respectively, and optical wavelength division multiplexer is used to separate Stokes light signal and anti-Stokes light signal in Raman scattering light, first optical detector is used to convert Stokes light signal into Stokes electrical signal, and second optical detector is used to convert anti-Stokes light signal into anti-Stokes electrical signal.The embodiment of the application realizes the fusion of two independent optical fiber sensing systems, and realizes the simultaneous measurement of temperature and bending two parameters.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber sensing, and particularly relates to a multi-core optical fiber distributed sensing system and a measuring method. BACKGROUND

[0002] Distributed optical fiber sensing can measure information along the line of the optical fiber, and is widely used in long-distance line monitoring. By measuring different scattered light, different physical information of the optical fiber can be obtained. Among them, Raman distributed temperature sensing (RDTS) obtains temperature information by measuring the intensity of Raman scattered light. RDTS has outstanding advantages such as long-distance full-distributed measurement, anti-electromagnetic radiation, real-time continuous measurement, and has been explored in the past few decades. Raman distributed temperature sensing system has been widely used in power grid, oil and gas pipeline, nuclear industry and other fields. Due to easy deployment, single-end Raman distributed temperature sensing solution is usually used for remote temperature sensing. It collects backscattered anti-stokes (AS) and stokes (S) signals to filter out temperature-independent intensity changes. However, since the anti-stokes Raman scattered light and the stokes Raman scattered light have different wavelengths, this solution will be significantly affected by wavelength-dependent loss (WDL), thereby causing temperature measurement error. Among them, the anti-stokes has a shorter wavelength, which can avoid errors caused by wavelength-dependent loss and dispersion. In order to avoid the influence of wavelength-dependent loss, a double-end Raman distributed temperature sensing system using only AS signal (AS-only) emerges as the times require. The AS-only solution can improve the stability of the Raman distributed temperature sensing system by eliminating temperature errors caused by wavelength-dependent loss. However, in order to eliminate temperature-independent intensity changes, single-wavelength demodulation usually adopts a double-end detection scheme. Therefore, the double-end Raman distributed temperature sensing system solution is the first choice of single-wavelength demodulation in complex application environment. The commonly used double-end structure is the optical fiber folding method, in which the optical fiber is folded in half, and the two ends of the optical fiber are connected to the Raman distributed temperature sensing device. Then the backscattered anti-stokes signals at both ends are collected and demodulated to obtain the temperature curve. However, using a single optical fiber to form a loop may encounter difficulties in actual laying environment. For example, in actual application, it is necessary to fold two optical fibers or one optical fiber into a loop, which is extremely inconvenient to deploy. An improvement of single-end AS-only Raman distributed temperature sensing is to use a reflector at the end of the sensing optical fiber. However, strong reflection will cause saturation of the photodetector, and multiple reflections may occur due to one or more end faces of the optical fiber connection, thereby causing errors in temperature demodulation.

[0003] In another aspect, in application scenarios such as power communication optical cable and cable tunnel monitoring, it is required to simultaneously complete distributed temperature sensing and distributed bending sensing in the idle core or sensing optical fiber of the power communication optical cable. Limited by the remaining number of idle cores or sensing optical fiber cores, it is required to multiplex temperature sensing and bending sensing on a limited number of cores, and temperature parameter demodulation needs to be independent of bending parameter demodulation. However, the change of backscattered Stokes light and anti-Stokes light at any position of the sensing optical fiber of the traditional Raman distributed optical fiber sensor is related to the temperature and bending of the optical fiber, so it is difficult to decouple the temperature and bending, which leads to the difficulty of qualitative analysis of the change of Raman scattered light in the actual application of the Raman distributed optical fiber sensing system, and limits its application in some scenarios. Multiplexing two independent distributed optical fiber sensing systems in a single optical fiber or a single core will increase the difficulty of signal separation and detection at the receiving end due to signal crosstalk and power problems, and also reduce the signal-to-noise ratio at the receiving end. SUMMARY

[0004] Embodiments of the present application provide a multi-core optical fiber distributed sensing system and a measurement method to realize the fusion of two independent optical fiber sensing systems and the simultaneous measurement of temperature and bending parameters.

[0005] In a first aspect, embodiments of the present application provide a multi-core optical fiber distributed sensing system, comprising a laser, a circulator and an optical fiber loop structure, the laser being connected to a first port of the circulator, and the optical fiber loop structure being connected to a second port of the circulator;

[0006] Further comprising an optical wavelength division multiplexer, a first optical detector and a second optical detector, the multiplexing port of the optical wavelength division multiplexer being connected to a third port of the circulator, and the two demultiplexing ports of the optical wavelength division multiplexer being connected to the first optical detector and the second optical detector respectively, the optical wavelength division multiplexer being used to separate Stokes light signals and anti-Stokes light signals in Raman scattered light, the first optical detector being used to convert the Stokes light signals into Stokes electrical signals, and the second optical detector being used to convert the anti-Stokes light signals into anti-Stokes electrical signals.

[0007] Optionally, an optical switch is further included, which is connected between the optical fiber loop structure and the second port of the circulator.

[0008] Optionally, the optical fiber loop structure comprises a first multi-core fiber fan-in fan-out module, a second multi-core fiber fan-in fan-out module and a multi-core fiber.

[0009] The two output ports of the optical switch are connected with two ports of the first multicore fiber fan-in / fan-out module, the first multicore fiber fan-in / fan-out module is connected with the second multicore fiber fan-in / fan-out module through the multicore fiber, and the two ports of the second multicore fiber fan-in / fan-out module are connected through single-mode optical fibers.

[0010] Optionally, the multicore fiber includes a central core and a bias core.

[0011] The two ports of the first multicore fiber fan-in / fan-out module connected with the optical switch correspond to the central core and the bias core respectively.

[0012] Optionally, the system further includes a data acquisition card and a central processing unit.

[0013] The two channels of the data acquisition card are connected with the first optical detector and the second optical detector respectively, and are used to receive the Stokes electric signal and the anti-Stokes electric signal.

[0014] The central processing unit is connected with the data acquisition card, and is used to demodulate temperature data from the anti-Stokes electric signal and demodulate bending data from the Stokes electric signal.

[0015] Optionally, the laser is further connected with a trigger port of the data acquisition card, and is used to trigger the data acquisition card to receive the Stokes electric signal and the anti-Stokes electric signal synchronously when emitting a laser pulse.

[0016] Optionally, the system further includes a doped fiber amplifier, which is connected between the laser and the first port of the circulator.

[0017] In a second aspect, an embodiment of the present application provides a measurement method based on the multicore fiber distributed sensing system of the first aspect, including:

[0018] Collecting measurement light intensity data by the first optical detector and the second optical detector, the measurement light intensity data being light intensity data in a measurement process, including an anti-Stokes light signal and a Stokes light signal;

[0019] Demodulating temperature T(z) of different positions of the sensing optical fiber along a line according to the anti-Stokes light signal obtained by the second optical detector;

[0020] Demodulating bending loss B(z, R) of different positions of the sensing optical fiber along the line according to the Stokes light signal obtained by the first optical detector and the temperature of different positions of the sensing optical fiber along the line.

[0021] Optionally, the following conditions are met:

[0022]

[0023] wherein z is a position, T(z) is a temperature at the position z, T0 is an ambient temperature at a reference optical fiber, J is a geometric mean set at the position z in two arithmetic mean result sets, and J0 is a first element of the geometric mean set;

[0024]

[0025] wherein h is a Planck constant, k is a Boltzmann constant, and Δv is a Raman shift.

[0026] Optionally, the following is satisfied:

[0027]

[0028] wherein φ s is an optical intensity of the sensing optical fiber at the position z, φ rs is an optical intensity of the reference optical fiber, is an optical intensity of the reference optical fiber collected in a pre-calibration stage, is an optical intensity of the sensing optical fiber at the position z collected in the pre-calibration stage, and Tc(z) is an optical intensity of the sensing optical fiber at z measured in the pre-calibration stage.

[0029] The multi-core optical fiber distributed sensing system provided by the embodiment of the present application separates Stokes light and anti-Stokes light in the back Raman scattering light in the sensing optical fiber through an optical wavelength division multiplexer. A first optical detector is used to detect a Stokes light signal (i.e., Stokes light), and a Stokes electrical signal is formed according to the Stokes light signal. A second optical detector is used to detect an anti-Stokes light signal (i.e., anti-Stokes light), and an anti-Stokes electrical signal is formed according to the anti-Stokes light signal. Thus, temperature and bending sensing information can be obtained according to the Stokes electrical signal and the anti-Stokes electrical signal, respectively, and two independent optical fiber sensing systems are fused together to realize simultaneous measurement of two parameters of temperature and bending. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 FIG. 1 is a schematic diagram of a multi-core optical fiber distributed sensing system provided by an embodiment of the present application;

[0031] Figure 2 FIG. 2 is a flowchart of a measurement method based on the multi-core optical fiber distributed sensing system provided by an embodiment of the present application. DETAILED DESCRIPTION

[0032] The present application will be further described below in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, only the parts related to the present application are shown in the drawings, but not all the structures.

[0033] Figure 1 A schematic diagram of a multi-core fiber distributed sensing system is provided for an embodiment of the present application, referring to Figure 1 The multi-core fiber distributed sensing system comprises a laser 10, a circulator 30 and a fiber loop structure 50. The laser 10 is connected to a first port of the circulator 30, and the fiber loop structure 50 is connected to a second port of the circulator 30. The multi-core fiber distributed sensing system further comprises an optical wavelength division multiplexer 60, a first optical detector 71 and a second optical detector 72. A multiplexing port of the optical wavelength division multiplexer 60 is connected to a third port of the circulator 30. Two demultiplexing ports of the optical wavelength division multiplexer 60 are connected to the first optical detector 71 and the second optical detector 72 respectively. The optical wavelength division multiplexer 60 is used to separate the Stokes light signal and the anti-Stokes light signal in the Raman scattered light. The first optical detector 71 is used to convert the Stokes light signal into a Stokes electrical signal, and the second optical detector 72 is used to convert the anti-Stokes light signal into an anti-Stokes electrical signal.

[0034] The multi-core fiber distributed sensing system provided by the embodiment of the present application separates the Stokes light and the anti-Stokes light in the back Raman scattered light in the sensing fiber through the optical wavelength division multiplexer 60. The first optical detector 71 is used to detect the Stokes light signal (i.e. the Stokes light), and the Stokes electrical signal is formed according to the Stokes light signal. The second optical detector 72 is used to detect the anti-Stokes light signal (i.e. the anti-Stokes light), and the anti-Stokes electrical signal is formed according to the anti-Stokes light signal. Thus, the temperature and the bending sensing information can be obtained according to the Stokes electrical signal and the anti-Stokes electrical signal respectively, and two independent optical fiber sensing systems are fused together to realize the simultaneous measurement of the two parameters of temperature and bending.

[0035] Exemplarily, referring to Figure 1 The laser 10 emits a laser pulse, the laser pulse is transmitted to the second port of the circulator 30 via the first port of the circulator 30, and is transmitted to the fiber loop structure 50 by the second port of the circulator 30. The laser pulse processed by the fiber loop structure 50 is transmitted to the third port of the circulator 30, and is transmitted to the optical wavelength division multiplexer 60 by the third port of the circulator 30, and then the Stokes light signal and the anti-Stokes light signal in the Raman scattered light can be separated by the optical wavelength division multiplexer 60.

[0036] Exemplarily, referring to Figure 1 The laser 10 emits a laser pulse, the width of the laser pulse is 30 ns, and the wavelength of the laser pulse generated by the laser 10 is 1550 nm.

[0037] Optionally, referring to Figure 1The multi-core optical fiber distributed sensing system further comprises an optical switch 40 connected between the optical fiber loop structure 50 and the second port of the circulator 30. One side port of the optical switch 40 is connected to the optical fiber loop structure 50, and the other side port of the optical switch 40 is connected to the second port of the circulator 30.

[0038] For example, referring to Figure 1 The optical switch 40 is a multi-path optical switch, specifically a 1x2 optical switch. The optical switch 40 has a control interface for switching control. The control interface of the optical switch 40 is connected to the central processor 90 for switching the direction of the optical path under the control of the central processor 90. The control interface of the optical switch 40 is connected to the I / O channel of the central processor 90. The optical switch 40 is used to switch the direction of the optical path through different cores. By measuring the backscattered anti-Stokes light in the two cores, the result can be self-calibrated to eliminate the influence of temperature-independent light intensity changes. In other embodiments, in the embodiment where the central processor 90 lacks an I / O channel, the control interface of the optical switch 40 can be connected to the data acquisition card 80.

[0039] Optionally, referring to Figure 1 The optical fiber loop structure 50 comprises a first multi-core fiber fan-in fan-out module 51, a second multi-core fiber fan-in fan-out module 52, and a multi-core fiber 53. The two output ports of the optical switch 40 are respectively connected to the two ports of the first multi-core fiber fan-in fan-out module 51, the multi-core fiber 53 is connected between the first multi-core fiber fan-in fan-out module 51 and the second multi-core fiber fan-in fan-out module 52, and the two ports of the second multi-core fiber fan-in fan-out module 52 are connected by a single-mode optical fiber. Due to the spatial consistency of the first multi-core fiber fan-in fan-out module 51 and the second multi-core fiber fan-in fan-out module 52, the result can be improved by averaging the temperature of the two cores. This single-end loop structure does not require a separate optical fiber loop to be laid, reducing the difficulty and cost of actual construction.

[0040] The embodiment of the present application injects a single beam of light signal of high homogeneity multi-core fiber 53 to generate Raman scattered light, respectively utilizes the different components of the Raman scattered light signal which are easily affected by temperature and fiber bending, but also considers that the Stokes light will still be affected by a large temperature change, and demodulates the temperature data from the anti-Stokes signal, and then demodulates the bending physical quantity data from the light intensity data in the Stokes light signal. The embodiment of the present application combines two independent distributed sensing systems together, while reducing the use amount of cores, also improves the accuracy of bending physical quantity demodulation.

[0041] For example, the multi-core fiber 53 is specifically a homogeneous multi-core fiber, the cores of the homogeneous multi-core fiber are not only consistent in size, but also consistent in refractive index. The homogeneous multi-core fiber can be a 7-core fiber.

[0042] Optionally, the multicore optical fiber 53 comprises a central core and a core offset. The two ports of the first multicore fiber fan-in fan-out module 51 connected with the optical switch 40 correspond to the central core and a core offset respectively. When the multicore optical fiber 53 is bent, the central core is not stressed, while the Raman scattering generated by the core offset is sensitive to the bending.

[0043] Optionally, referring to Figure 1 , the multicore optical fiber distributed sensing system further comprises a data acquisition card 80 and a central processing unit 90. Two channels of the data acquisition card 80 are connected with the first optical detector 71 and the second optical detector 72 respectively, and the data acquisition card 80 is used to receive the Stokes electrical signal and the anti-Stokes electrical signal. The central processing unit 90 is connected with the data acquisition card 80, and the central processing unit 90 is used to demodulate the temperature data from the anti-Stokes electrical signal and the bending data from the Stokes electrical signal.

[0044] Optionally, referring to Figure 1 , the laser 10 is further connected with a trigger port of the data acquisition card 80, and the laser 10 is further used to trigger the data acquisition card 80 to receive the Stokes electrical signal and the anti-Stokes electrical signal synchronously when emitting the laser pulse.

[0045] Optionally, referring to Figure 1 , the multicore optical fiber distributed sensing system further comprises a doped fiber amplifier 20 connected between the laser 10 and the first port of the optical circulator 30. The laser 10 is connected with the doped fiber amplifier 20, and the doped fiber amplifier 20 is connected with the first port of the optical circulator 30.

[0046] Figure 2 A flow chart of a measurement method based on the multicore optical fiber distributed sensing system is provided for the embodiment of the present application, referring to Figure 1 and Figure 2 , the measurement method based on the multicore optical fiber distributed sensing system comprises:

[0047] S110, collecting measurement light intensity data by the first optical detector and the second optical detector, the measurement light intensity data being the light intensity data in the measurement process, including the anti-Stokes light signal and the Stokes light signal.

[0048] S120, demodulating the temperature T(z) of different positions along the sensing optical fiber according to the anti-Stokes light signal obtained by the second optical detector.

[0049] S130, demodulating the bending loss B(z, R) of different positions along the sensing optical fiber according to the Stokes light signal obtained by the first optical detector and the temperature of different positions along the sensing optical fiber.

[0050] In the embodiment of the present application, in order to realize the synchronization of bending and temperature and discriminative measurement, the ROTDR (Raman Optical Time-Domain Reflectometry) is used to detect the loss characteristics of Raman Stokes light, so as to obtain the curvature information (i.e. bending information). Compared with anti-Stokes light, the intensity of Stokes light is less affected by temperature. Moreover, the wavelength of Stokes light is larger than that of anti-Stokes light and Rayleigh backscattering light, and the Stokes light is more likely to leak when the optical fiber is bent. Therefore, the bending loss is equivalent to the bending detection, that is, the demodulation result of the bending loss is taken as the bending detection result. Although the Stokes light is less sensitive to temperature change compared with the anti-Stokes light, the influence of temperature on the intensity of Stokes light still exists when the environmental temperature changes greatly. In order to avoid the influence of temperature on the curvature measurement, the temperature demodulation is performed first, and the temperature demodulation result T(z) of the sensing optical fiber is introduced into the bending loss demodulation.

[0051] Optionally, the temperature T(z) satisfies:

[0052]

[0053] wherein z is a position, T(z) is a temperature at the position z, T0 is an environmental temperature at a reference optical fiber, J is a geometric mean set at the position z in two arithmetic mean result sets, and J0 is a first element of the geometric mean set.

[0054]

[0055] wherein h is a Planck constant, k is a Boltzmann constant, and Δv is a Raman frequency shift.

[0056] Optionally, the bending loss B(z, R) satisfies:

[0057]

[0058] wherein φ s is an optical intensity of the sensing optical fiber at the position z, φ rs is an optical intensity of the reference optical fiber, is an optical intensity of the reference optical fiber collected in the pre-calibration stage, is an optical intensity of the sensing optical fiber at the position z collected in the pre-calibration stage, and Tc(z) is an optical intensity of the sensing optical fiber at z measured in the pre-calibration stage. The parameters in the formula satisfied by the temperature T(z) are not repeated here.

[0059] Optionally, in the measurement method based on the multi-core optical fiber distributed sensing system, the pre-calibration step can be further included before the above step S10.

[0060] S11, acquire the ambient temperature T0 of the reference optical fiber; collect the light intensity of the Stokes light of the sensing optical fiber and the reference optical fiber to obtain and

[0061] wherein, is the light intensity of the reference optical fiber collected in the pre-calibration stage, is the light intensity of the sensing optical fiber at position z collected in the pre-calibration stage.

[0062] S12, collect calibration light intensity data through the first light detector and the second light detector, the calibration light intensity data being the light intensity data in the pre-calibration stage, including the anti-Stokes light signal and the Stokes light signal.

[0063] S13, demodulate the temperature Tc(z) of the entire sensing optical fiber.

[0064] wherein, the temperature Tc(z) satisfies:

[0065]

[0066] The parameters introduced in the formula satisfied by the temperature T(z) are not repeated here.

[0067] Optionally, the measurement method based on the multi-core optical fiber distributed sensing system further includes the collection and processing of data in the data acquisition card 80, and specifically includes:

[0068] S21, simultaneously collect multiple data by two channels of the data acquisition card, and perform arithmetic averaging on the data of the same point. For example, 60,000 times of data are simultaneously collected by two channels of the data acquisition card.

[0069] S22, control the light switch to switch the direction of light propagation.

[0070] S23, simultaneously collect multiple data by two channels of the data acquisition card, and perform arithmetic averaging on the data of the same point. For example, 60,000 times of data are simultaneously collected by two channels of the data acquisition card.

[0071] S24, perform geometric averaging of the same point on the two arithmetic average results of each channel.

[0072] In this step, geometric averaging of the same point is performed on the two arithmetic average results of each channel in the two channels.

[0073] In the embodiment of the application, compared with the multi-fiber cable, the spatial consistency of the first multi-core optical fiber fan-in fan-out module 51 and the second multi-core optical fiber fan-in fan-out module 52 is higher, and the application averages the Stokes light and anti-Stokes light data collection results of the two cores, thereby reducing noise and improving the signal-to-noise ratio of the sampling data.

[0074] Note that the above merely describes preferred embodiments of the present application and the principles of the technology applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, modifications, combinations and substitutions can be made by those skilled in the art without departing from the scope of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the claims.

Claims

1. A multi-core fiber optic distributed sensing system, characterized in that, It includes a laser, a circulator, and an optical fiber loop structure, wherein the laser is connected to a first port of the circulator, and the optical fiber loop structure is connected to a second port of the circulator; It also includes an optical wavelength division multiplexer, a first photodetector, and a second photodetector. The multiplexing port of the optical wavelength division multiplexer is connected to the third port of the circulator. The two demultiplexing ports of the optical wavelength division multiplexer are respectively connected to the first photodetector and the second photodetector. The optical wavelength division multiplexer is used to separate the Stokes light signal and the anti-Stokes light signal in the Raman scattered light. The first photodetector is used to convert the Stokes light signal into a Stokes electrical signal, and the second photodetector is used to convert the anti-Stokes light signal into an anti-Stokes electrical signal. It also includes an optical switch, which is connected between the optical fiber loop structure and the second port of the circulator; It also includes a data acquisition card and a central processing unit; The two channels of the data acquisition card are respectively connected to the first photodetector and the second photodetector, and are used to receive the Stokes electrical signal and the anti-Stokes electrical signal; The central processing unit is connected to the data acquisition card and is used to demodulate the temperature at different locations along the sensing fiber from the anti-Stokes electrical signal. The bending loss at different locations along the sensing fiber is demodulated from the Stokes electrical signal and the temperature at different locations along the sensing fiber. ; The process of acquiring and processing data from the data acquisition card specifically includes: The data acquisition card collects data multiple times simultaneously through its two channels, and then performs an arithmetic average on the data from the same location. Control the optical switch to switch the direction of light propagation; The data acquisition card collects data multiple times simultaneously through its two channels, and then performs an arithmetic average on the data from the same location. For each channel, calculate the geometric mean of the two arithmetic mean results at the same points. temperature satisfy: ； in, For location, For position The temperature at that location To reference the ambient temperature at the fiber optic cable, Position in the set of two arithmetic mean results The geometric mean set at that location The first element of the geometric mean set; ； in, Let be Planck's constant. Boltzmann's constant, For Raman frequency shift; Bending loss satisfy: ； in, For sensing fiber at position The light intensity at that location, For the reference fiber's light intensity, The light intensity of the reference fiber collected during the pre-calibration phase. The sensing fiber optic data collected during the pre-calibration phase is located at... The light intensity at that location, For the sensing fiber measured in the pre-calibration stage The temperature at that location.

2. The multi-core fiber optic distributed sensing system according to claim 1, characterized in that, The optical fiber loop structure includes a first multi-core optical fiber fan-in fan-out module, a second multi-core optical fiber fan-in fan-out module, and multi-core optical fibers. The two output ports of the optical switch are respectively connected to the two ports of the first multi-core fiber fan-in fan-out module. The first multi-core fiber fan-in fan-out module and the second multi-core fiber fan-in fan-out module are connected by the multi-core fiber. The two ports of the second multi-core fiber fan-in fan-out module are connected by a single-mode fiber.

3. The multi-core fiber optic distributed sensing system according to claim 2, characterized in that, The multi-core optical fiber includes a central core and a lateral core; The two ports of the first multi-core fiber fan-in / fan-out module, which is connected to the optical switch, correspond to the central fiber core and one of the off-cores, respectively.

4. The multi-core fiber optic distributed sensing system according to claim 1, characterized in that, The laser is also connected to the trigger port of the data acquisition card, and is used to synchronously trigger the data acquisition card to receive the Stokes electrical signal and the anti-Stokes electrical signal when emitting laser pulses.

5. The multi-core fiber optic distributed sensing system according to claim 1, characterized in that, It also includes an erbium-doped amplifier connected between the laser and the first port of the circulator.

6. A measurement method based on the multi-core fiber optic distributed sensing system of claim 1, characterized in that, include: The light intensity data is collected by the first photodetector and the second photodetector. The light intensity data is the light intensity data during the measurement process, including the anti-Stokes light signal and the Stokes light signal. Based on the anti-Stokes light signal acquired by the second photodetector, the temperature at different locations along the sensing fiber is demodulated. ; Based on the Stokes light signal acquired by the first photodetector and the temperature at different locations along the sensing fiber, the bending loss at different locations along the sensing fiber is demodulated. .

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