WO2014101754A1

WO2014101754A1 - Multi-core optical fibre, sensing device adopting multi-core optical fibre and running method therefor

Info

Publication number: WO2014101754A1
Application number: PCT/CN2013/090356
Authority: WO
Inventors: 杜兵
Original assignee: 西安金和光学科技有限公司
Priority date: 2012-12-26
Filing date: 2013-12-24
Publication date: 2014-07-03
Also published as: CN103901532A

Abstract

A multi-core optical fibre and a sensor based on the multi-core optical fibre and a running method therefor. The multi-core optical fibre comprises a transmission fibre core (15) and a plurality of sensing fibre cores (16), the length of the sensing fibre core (16) being not less than the length of the transmission fibre core (15). The sensor based on the multi-core optical fibre comprises a light source module (12), the multi-core optical fibre and optical detector modules (5, 7, 8). The light source module (12) injects optical signals in the transmission fibre core (15). The optical detector modules (5, 7, 8) detect the variation of optical signals in all or a part of the sensing fibre cores (16), eliminate interference through the comparison of the response of more than two sensing fibre cores (16) to the physical quantities to be detected in one and the same position, and improve the test accuracy. Also disclosed is a corresponding running method for the sensor based on the multi-core optical fibre.

Description

Multi-core optical fiber, sensing device using the same, and operating method thereof

The invention relates to a novel multi-core optical fiber and a sensing device based on the multi-core optical fiber, in particular to a multi-core optical fiber comprising three cores or more than three cores, and a point type based on the multi-core optical fiber Or distributed fiber optic sensing devices and methods of operation thereof.

Background technique

Chinese Patent Application No. 201120130642. 5 The "Twin-Core Based Temperature Sensing Device" patent discloses a temperature sensing device that uses a broadband source, a dual-core fiber, and a spectrum analyzer. When the temperature changes, the dual-core fiber The distance between the two cores also changes, resulting in a change in the wavelength of the optical signal of the core in which the broadband optical signal is injected is coupled to the core of the uninjected optical signal, and the change is detected by the optical spectrum analyzer, thereby completing The temperature monitoring is simple in structure and wide in temperature monitoring, but its test parameters are single, the instrument is expensive, and distributed monitoring cannot be realized.

The existing distributed or quasi-distributed optical fiber sensing devices are mainly inspection devices for backscattered light in optical fibers, including the most commonly used optical time domain reflectometer (0TDR), fiber Raman temperature sensing device, Brillouin scattering sensing device and Bragg fiber grating sensing device. In the first three sensing devices, since the backscattered light containing the sensing information in the optical fiber is small relative to the incident light, the general backscattered light ratio is generally The power of the forward transmission optical signal is three to six orders of magnitude small, so the detection of backscattered light is difficult. In order to remove the noise, it is often necessary to use the sampling integrator for many times to extract the weak signal, thereby making the monitoring equipment more complicated and costly. High and low real-time performance, and the maximum distance monitored by it is less than 100 km; while the quasi-distributed optical fiber sensing device composed of Bragg fiber grating has a strong reflected light signal, but the optical signal between the fiber gratings is easy. Mutual interference, so the number of fiber gratings is small, and the number of fiber gratings on each fiber is only a few dozen at most, which is difficult to achieve. On the other hand, the existing optical fiber communication technology is developing rapidly, and the distance of its non-relay communication is easily more than several hundred kilometers. If the erbium-doped or Raman fiber amplification device is used, it can reach thousands of kilometers. The main reason is that the intensity of the forward-propagating optical signal is much greater than that of the back-scattered optical signal. If there is a distributed sensing device that monitors the change of the optical signal based on forward transmission, the distributed optical fiber can be greatly extended. The distance monitored, however, such a device is not currently retrieved. Summary of the invention

The invention discloses a multi-core optical fiber and a sensing device based on the multi-core optical fiber, A core fiber is an optical fiber having three or more cores, such as a three-core fiber, a four-core fiber, or a five-core fiber. By detecting changes in optical signal transmission in all or part of the core, point or distributed can be achieved. The purpose of the monitoring. And there are two or more sensing cores, and by comparing the difference of the optical signals transmitted in the two sensing cores, the fluctuation of the optical power generated by the non-measurement physical quantity in the light source or the optical signal transmission can be eliminated, thereby Eliminating the error introduced by it, it proposes a new solution for the practical application of the intensity type fiber sensing device. The optical fiber sensing device has the advantages of convenient use, low cost and good application prospect.

In order to solve the above technical problems, the technical solution adopted by the present invention is:

A multi-core optical fiber comprising an inner cladding of an optical fiber and a core disposed in the inner cladding, wherein at least three cores are disposed on the inner cladding, wherein one core is a transmission core, and the other core is sensed The core, each sensing core has a length not less than the length of the transmission core, and at least one of the sensing cores has a length greater than a length of the transmission core.

Further, the inner cladding has an outer cladding layer, and the inner cladding layer has a refractive index greater than the outer cladding refractive index. Preferably, the cross section of the inner cladding along the radial direction of the optical fiber is a non-circular symmetric defect cladding. The radial cross section of the non-circular symmetric defect cladding layer may be a rectangle, a part of a circular shape, an elliptical shape, a polygonal shape, etc., so that when the optical signal is propagated in the transmission core, part of the escaped optical signal does not Near the inner cladding and the outer edge of the outer cladding, the edge portion is propagated and consumed, but is reflected and passed through the transmission core or the sensing core, which is eventually captured by the core, thereby reducing the attenuation of optical signal transmission. .

Preferably, the sensing core is arranged in a spiral shape in the inner cladding. Further, the sensing core is disposed around the transmission core in a spiral shape, and the transmission core is located at an axial center position of the spiral formed by the sensing core. Preferably, the transmission core is located at an axial center position of the entire optical fiber.

Preferably, each of the sensing cores has a different distance from the transmission core. Therefore, different sensing cores acquire different optical signal sizes at the same physical quantity to be measured, and the comparison between the two can eliminate the error introduced by the light source or other non-measured physical quantity caused by the fluctuation of the optical signal size, thereby The test results of the intensity type optical fiber sensing device are more accurate and practical.

Further, at least two of the sensing cores have different refractive index indices. Different sensing cores have different ability to capture optical signals and bind optical signals, which is convenient for eliminating test errors. Preferably, at least two of the sensing cores have different core diameters.

Further, the multi-core optical fiber is an optical fiber composed of a polymer material, an optical fiber composed of multi-component glass, an optical fiber composed of fluoride glass, or an optical fiber composed of quartz glass.

A fiber-optic sensing device based on a multi-core fiber, comprising a control module, a light source module, a coupling module, a photodetector module, and a processing module, wherein the control module is coupled to the light source module and controls the latter to emit an optical signal, and the light source module and the coupling The module is connected, the coupling module is connected to one end of the multi-core fiber, and the multi-core fiber has at least three cores disposed on the inner cladding, wherein one core is transmitted The fiber core, the other core is a sensing core, and at least one sensing core has a different length than the length of the transmitting core; the coupling module is a transmission fiber that couples the optical signal only into the multi-core fiber. a coupling module of the core; the other end of the multi-core fiber is connected to the photodetector module, and the photodetector module simultaneously acquires optical signals transmitted in each core of the multi-core fiber, and the photodetector module Processing module connection.

The way to run it is: The steps are as follows:

1) comprising a sensing fiber, wherein the length of the transmission core and the sensing core are different, the control module controls the light source module to emit a pulsed light signal, and the pulsed light signal is injected into the transmission core of one end of the multi-core fiber through the coupler Internal transmission

2) The pulsed optical signal is transmitted from one end of the multi-core optical fiber to the other end in the transmission core, and is acquired by the photodetector module disposed at the other end of the multi-core optical fiber, and the photodetector module converts the pulsed optical signal into The electrical signal is transmitted to the processing module;

3) When somewhere on the multi-core fiber is changed by the physical quantity to be measured, the optical signal transmitted in the transmission core is partially coupled into two or more sensing cores and in each sensing fiber In-core transmission, since the transmission core and the sensing core have different lengths, the optical signal has different transmission speeds between the two, and the optical signals in the transmission core and the sensing core are sequentially arranged to reach the multi-core optical fiber. One end is acquired by the photodetector module, and the photodetector module converts the acquired optical signal into an electrical signal and transmits it to the processing module. The processing module calculates the size and position of the physical quantity to be measured according to the size and time interval of the electrical signal. Thereby completing the purpose of monitoring. Preferably, the fiber-optic sensing device based on the multi-core fiber is connected to the coupling module 2 at the other end of the multi-core fiber, and the coupling module 2 includes at least two channels, and each channel has no interference with each other. The at least two sensing cores in the multi-core fiber are respectively connected to the two channels, and are respectively connected to the photodetector module 1 and the photodetector module 2 through the coupling module 2; the photodetector module 1 and the photodetector module 2 Connect to the processing module.

The steps of its operation method are as follows:

2) The pulsed optical signal is transmitted from one end of the multi-core optical fiber to the other end in the transmission core, and the coupling module 2 is disposed at the other end of the multi-core optical fiber, and the coupling module 2 includes at least two channels, each of which The channels are not interfered with each other, and at least two sensing cores in the multi-core fiber are respectively connected to two channels, and are respectively connected to the photodetector module 1 and the photodetector module 2 through the coupling module 2; The module 1 and the photodetector module 2 are connected to the processing module;

3) When a certain part of the multi-core fiber is changed by the physical quantity to be measured, the transmission core is transmitted internally. The transmitted optical signal is partially coupled into two or more sensing cores and transmitted within each sensing core, wherein at least two of the sensing optical signals transmitted within the core are respectively received by the photodetector module The two photodetector modules respectively convert the optical signal into an electrical signal and transmit it to the processing module, and the processing module eliminates the light source or the non-test according to the size of the two electrical signals and the comparison between the two. The error introduced by the change of the optical signal power caused by the influence of the physical quantity, and then the time interval, thereby calculating the size and position of the physical quantity to be measured, and completing the purpose of monitoring.

A further preferred solution of the fiber-optic sensing device based on the multi-core fiber is that the other end of the multi-core fiber is connected to the coupling module three, and the coupling module three includes at least three channels, and each channel has no interference with each other. At least two sensing cores and a transmitting core in the multi-core fiber are respectively connected to three channels, and through the coupling module three respectively, a photodetector module, a photodetector module 2 and a photodetector module three The photodetector module 1, the photodetector module 2 and the photodetector module 3 are connected to the processing module.

The operation steps of the program are as follows:

2) The pulsed optical signal is transmitted from one end of the multi-core optical fiber to the other end in the transmission core, and the coupling module 3 is disposed at the other end of the multi-core optical fiber, and the coupling module 3 includes at least three channels, each of which The channels are not interfered with each other, and at least two sensing cores and transmission cores in the multi-core fiber are respectively connected to three channels, and the photodetector module and the photodetector module are respectively connected through the coupling module three. The second and the photodetector modules are connected; the photodetector module 1, the photodetector module 2 and the photodetector module 3 are connected to the processing module;

3) When somewhere on the multi-core fiber is changed by the physical quantity to be measured, the optical signal transmitted in the transmission core is partially coupled into two or more sensing cores and in each sensing fiber In-core transmission, wherein at least two sensing cores and optical signals transmitted in the transmission core are respectively obtained by the photodetector module 1, the photodetector module 2 and the photodetector module 3, and the three photodetector modules respectively The optical signal is converted into an electrical signal and transmitted to the processing module. The processing module eliminates the influence of the light source or the unmeasured physical quantity according to the size of the electrical signal transmitted by the photodetector module 1 and the photodetector module 2 and the comparison between the two. The error introduced by the change of the optical signal power, and then the time interval of the electrical signal transmitted by the photodetector module three, thereby calculating the size and position of the physical quantity to be measured, and completing the monitoring, the photodetector module The light detector module 2 and the light detecting module 3 are one of an optical power meter, a photon counter, a spectrum analyzer, and a wavelength meter.

Preferably, the light source module is one of a single wavelength light source, a multi-wavelength light source or a broadband light source. Preferably, the light reflecting device is a fiber grating, a light reflecting mirror or an optical fiber containing bubbles. The present invention has the following advantages over the prior art:

1. The forward monitoring technology enables the optical signal to be transmitted at a long distance, meeting the actual needs of natural gas pipelines and petroleum pipelines. Compared with the current Brillouin scattering monitoring device on the market, it has the advantages of low cost, long monitoring distance and high precision. , has a good market prospects.

2. Since the sensing fiber used has at least three cores, at least one of which is an optical signal transmission core, and at least one of the sensing cores has a length greater or smaller than the transmission core, the optical signal is The speed of transmission in the transmission core and the sensing core is different. When the multi-core fiber changes, such as microbending, bending, deformation, temperature change, and other physical quantity changes, the injected optical signal escapes and has a part. Coupling into the sensing core of the uninjected optical signal, and being captured by the photodetector module at the end of the multi-core fiber, detecting the pulsed optical signal and containing the physical quantity to be measured due to the difference in the transmission speed of the optical signals in the two cores The other optical signal in the sensing core reaches the photodetector module in order, thereby distinguishing the size and time interval of different optical signals, and the size of the physical quantity to be measured can be known according to the size of the optical signal containing the physical quantity to be measured. According to the interval between the detecting pulse optical signal and the optical signal containing the physical quantity to be measured, the position of the physical quantity to be measured can be calculated, thereby completing the distributed The purpose of monitoring. When there are multiple changes on the multi-core fiber, a sequence of multiple pulsed optical signals is formed.

3. Since at least two sensing cores are included, and the physical parameters of the two sensing cores are different, such as different distances from the transmission core, different refractive index indexes, and different lengths, coupling into the two from the transmission core The optical signals of the sensing cores are also different. By comparing the difference in the size of the transmitted optical signals in the two sensing cores, the influence of the fluctuation of the light source fluctuations can be eliminated, the test error can be reduced, or the detection dynamics of the optical fiber sensing device can be improved. Scope; or two different physical quantity parameters can be monitored at the same time, such as monitoring the temperature and strain parameters of a position at the same time, which increases the test parameters of the fiber-optic sensing device and extends the range of use.

4. Since the device injects optical signals into only one transmission core in the multi-core fiber and detects the optical signals in the other sensing core, this is a dark field monitoring technology with high precision and accuracy.

In summary, the multi-core optical fiber and the optical fiber sensing device based on the multi-core optical fiber have the advantages of simple structure, low cost, long monitoring distance, and can realize point or distributed monitoring and sensing, and have better performance. market expectation.

The technical solution of the present invention will be further described in detail below through the accompanying drawings and embodiments.

DRAWINGS

1 is a schematic structural view of Embodiment 1 of the present invention.

2 is a schematic structural view of a cross section of the multi-core optical fiber of FIG. 1.

Fig. 3 is a structural schematic view showing the refractive index distribution of the multi-core fiber in the radial direction of Fig. 2.

Figure 4 is a partial schematic view of a multi-core fiber.

Figure 5 is a schematic cross-sectional view of a multi-core fiber with a defective inner cladding.

Figure 6 is a schematic structural view of Embodiment 2 of the present invention. FIG. 7 is a schematic structural view of Embodiment 3 of the present invention. Description of the reference signs:

4 coupling module three; 5 - photodetector module three; 6 - processing module;

7-photodetector module one; 8-photodetector module two;

9 coupling module 2; 10 - control module; 11 a multi-core fiber; 12 - light source module;

13 coupling module one; 14 one output module; 15 - transmission core; 16 - sensing core;

19-auxiliary fiber; 24-outer layer; 25-coating layer;

33—Light reflecting device.

Specific ii^

Example 1

As shown in FIG. 1, FIG. 2, FIG. 3 and FIG. 4, a multi-core optical fiber and a multi-core optical fiber-based optical sensing device, the optical fiber sensing device comprises a control module 10, a light source module 12, a coupling module 13, and a light The detector module 7 and the processing module 6, the control module 10 is connected to the light source module 12 and controls the latter to emit an optical signal, preferably a pulsed optical signal, and the light source module 12 and the coupling module 13 are connected by an auxiliary optical fiber 19, The coupling module 13 is connected to one end of the multi-core optical fiber 11. The multi-core optical fiber 11 has at least three cores disposed on the inner cladding 23, one of the cores is a transmission core 15, and the other core is sensed. The core 16 has at least one sensing core 16 having a different length than the length of the transmission core 15; the coupling module 13 is a coupling module for coupling the optical signal into the transmission core 15 in the multi-core optical fiber 11 The other end of the multi-core optical fiber 11 is connected to the photodetector module 7 , and the photodetector module 7 simultaneously acquires the optical signal transmitted in each core of the multi-core optical fiber 11 , and the photodetector module 1 7 is connected to the processing module 6. Preferably, the processing module 6 is connected to an output module 14, such as a terminal such as a display or a printer.

When performing distributed monitoring, since the multi-core optical fiber 11 is used, there are at least three cores, at least one of which is an optical signal transmission core 15, and at least one of the sensing cores 16 has a length greater or smaller. When the core 15 is transported, the speed at which the optical signal is transmitted in the transmission core 15 and the sensing core 16 is different. When the multi-core optical fiber 11 changes, such as microbending, bending, deformation, etc., the pulsed light is injected. The signal escapes and is partially coupled into the sensing core 16 of the near-uninjected optical signal, thereby being captured by the photodetector module 7 at the end of the multi-core optical fiber 11 due to the different transmission speeds of the optical signals in the two cores. The detecting pulse light signal and the optical signal in the other sensing core 16 containing the physical quantity to be tested arrive at the photodetector module 7 in order, thereby distinguishing the size and time interval of different optical signals, according to the inclusion of the test The size of the physical quantity of the optical signal can know the magnitude of the physical quantity to be measured, and the position of the physical quantity to be measured can be calculated according to the interval time between the detection pulse optical signal and the optical signal containing the physical quantity to be measured, thereby completing The purpose of distributed monitoring. When there are multiple changes in the multi-core fiber 11, a sequence of a plurality of pulsed optical signals is formed. When performing point monitoring, the light source module 12 emits a pulsed light signal And continuous optical signals can be used for monitoring purposes.

The photodetector module 7 , the photodetector module 28 , and the photodetecting module 3 17 may be one of an optical power meter, a photon counter, a spectrum analyzer, and a wavelength meter.

The light source module 12 can be one of a single wavelength source, a multi-wavelength source or a broadband source. For example, a single-wavelength light source is a DFB laser, and its output optical signal has a stable wavelength and a large power. The multi-wavelength source can be constructed from a plurality of DFB lasers.

When the photodetector module 7 , the photodetector module 2 , and the photodetector module 3 5 are optical power meter and photon counter testing instruments, preferably, the light source module 12 can be a single wavelength light source and a multi-wavelength light source. In one of the detectors of the device of the present invention, the power of the pulse or continuous optical signal is collected, and the magnitude of the physical quantity to be measured can be calculated according to the power level; when the photodetector module 7 and the photodetector module 2 Preferably, the light source module 12 is one of a multi-wavelength light source or a broadband light source, and the device of the present invention collects wavelength information of a pulse or a continuous optical signal, and Based on this information, the magnitude of the physical quantity to be measured can be derived.

The multi-core optical fiber is: an inner cladding 23 including an optical fiber and a core disposed in the inner cladding 23, and at least three cores are disposed on the inner cladding 23, wherein one core is a transmission core 21, and the other core is Sensing the core 16, each sensing core 16 has a length no less than the length of the transmission core, and at least one of the sensing cores 16 has a length greater than the length of the transmission core.

Or: The multi-core fiber 11 has at least three cores disposed on the inner cladding 23, one of the cores is the transmission core 15, and the other cores are the sensing cores 16, and the length of each sensing core 16 is not It is larger than the length of the transmission core 15, and at least one of the sensing cores 16 has a length smaller than the length of the transmission core 15.

Further, the inner cladding layer 23 has an outer cladding layer 24, and the inner cladding layer 23 has a refractive index greater than that of the outer cladding layer 24. Further, the inner cladding layer has an outer cladding layer, and the inner cladding layer has a refractive index index larger than that of the outer cladding layer.

Preferably, the cross section of the inner cladding 23 along the radial direction of the multi-core optical fiber 11 is a non-circular symmetric defect cladding layer, as shown in FIG. The radial cross section of the non-circular symmetric defect cladding layer may be a rectangle, a part of a circular shape, an elliptical shape, a polygonal shape, etc., so that when the optical signal is propagated in the transmission core 15, a part of the escaped optical signal does not It is absorbed near the edge portions of the inner cladding 23 and the outer cladding 24 and is consumed, but is reflected and passed through the transmission core 15 or the sensing core 16, which is eventually mostly captured by the core, thereby reducing Attenuation of optical signal transmission.

At least one of the sensing cores 16 is disposed in the inner cladding 23 in a spiral shape. Further, the pitches of the spirals are the same.

At least one of the sensing cores 16 is disposed in the inner cladding 23 in a spiral shape. Further, the pitches of the spirals are different.

The sensing core 16 is disposed around the transmission core 15 in a spiral shape.

The transmission core 15 is located at an axial center position of the spiral formed by the sensing core 16. The distances of the respective sensing cores 16 from the transmission core 15 are different.

The transmission core 15 is located at the axial center position of the entire multi-core optical fiber 11.

At least two of the sensing cores 16 have different refractive index indices.

At least two of the sensing cores 16 have different core diameters.

The multi-core optical fiber 11 is an optical fiber composed of a polymer material, an optical fiber composed of multi-component glass, an optical fiber composed of fluoride glass, or an optical fiber composed of quartz glass.

Example 2

An optical fiber sensing device as shown in FIG. 6 is different from the first embodiment in that the other end of the multi-core optical fiber 11 is connected to the coupling module 3, and the coupling module 3 4 includes three channels, each of which The channels are not interfered with each other. The at least two sensing cores 16 and the transmission cores 15 in the multi-core optical fiber 11 are respectively connected to three channels, and are respectively connected to the photodetector module through the coupling module 3 4 The photodetector module 2 and the photodetector module 3 are connected; the photodetector module 7 and the photodetector module 2 and the photodetector module 3 are connected to the processing module 6.

The operation steps of the program are as follows:

1) comprising a sensing fiber 11, wherein the length of the transmission core 15 and the sensing core 16 are different, the control module 10 controls the light source module 12 to emit a pulsed light signal, and the pulsed light signal is injected into the multi-core through the coupler 13 Transmission in the transmission core 15 at one end of the optical fiber 11;

2) The pulsed optical signal is transmitted from one end of the multi-core optical fiber 11 to the other end in the transmission core 15, and the coupling module 3 is disposed at the other end of the multi-core optical fiber 11, and the coupling module 3 4 includes at least three Channels, each channel having no interference with each other, at least two sensing cores 16 and transmission cores 15 in the multi-core fiber 11 are respectively connected to three channels, and respectively through the coupling module three 4 The photodetector module 7 , the photodetector module 2 8 and the photodetector module 3 5 are connected; the photodetector module 7 , the photodetector module 2 8 and the photodetector module 3 5 are connected to the processing module 6;

3) When somewhere on the multi-core optical fiber 11 is changed by the physical quantity to be measured, the optical signal transmitted in the transmission core 15 is partially coupled into two or more sensing cores 16 and The sensing core 16 transmits, wherein at least two of the sensing core 16 and the optical signal transmitted in the transmission core 15 are respectively acquired by the photodetector module 7, the photodetector module 2, and the photodetector module 3 The three photodetector modules respectively convert the optical signal into an electrical signal and transmit it to the processing module 6. The processing module 6 compares the size of the electrical signal transmitted by the photodetector module 7 and the photodetector module 2 and the comparison between the two. The error introduced by the change of the optical signal power caused by the influence of the light source or the unmeasured physical quantity is eliminated, and then the time interval of the electrical signal transmitted by the photodetector module 3 5 is used to calculate the magnitude and position of the physical quantity to be measured, and Complete the purpose of monitoring.

In this embodiment, if the coupling module 3 is replaced by the coupling module 2, and the coupling module 2 has independent dual channels, the two sensing cores 16 can be respectively connected to the photodetector module by the module. Detector module 2 8 connection, can also achieve the error introduced by eliminating the change of optical signal, and calculation The size and relative position of the physical quantity to be measured are obtained, and the purpose of monitoring is completed.

In this embodiment, the structure, connection relationship and working principle of the remaining portions are the same as those of the first embodiment. Example 3

As shown in FIG. 7 , the embodiment is different from the embodiment 1 in that: an optical fiber sensing device based on a multi-core optical fiber 11 includes a control module 10 , a light source module 12 , a coupling module 13 , and a photodetector module 7 . And the processing module 6, the control module 10 is connected to the light source module 12 and controls the latter to emit an optical signal, the light source module 12 is connected to the coupling module 13 , and the coupling module 13 is connected to one end of the multi-core optical fiber 11 The multi-core optical fiber 11 has at least three cores disposed on the inner cladding 23, one of the cores is a transmission core 15, and the other core is a sensing core 16, and at least one of the sensing cores 16 has a length and a transmission fiber. The length of the core 15 is different; the coupling module 13 has at least two channels, and each channel has no interference with each other, and one of the channels is a transmission fiber that causes the optical signal emitted by the light source module 12 to be coupled only into the multi-core fiber 11. The core 15 is connected to the sensing core 16 of the multi-core fiber 11 , and the transmitted optical signal in the sensing core 16 is connected to the photodetector module through the coupling module 13 , and the light is detected. 7 acquires the module 16 transmits a sensed core optical signal, a photodetector Ί module 6 is connected with the processing module; the other end of the multi-core optical fiber 11 of the light reflecting means 33 is disposed.

The light reflecting means 33 is a fiber grating, a light reflecting mirror or an optical fiber containing bubbles.

Preferably, the coupling module 13 disposed at one end of the multi-core optical fiber 11 includes at least three channels, each of which has no interference with each other, and at least two sensing fibers in the multi-core optical fiber 11 The core 16 and the transmission core 15 are respectively connected to three channels, and are respectively connected to the photodetector module 7, the photodetector module 2 and the light source module 12 through the coupling module 13; the photodetector module 7 and the light detecting The module module 2 is connected to the processing module 6; the photodetector module and the photodetector module 2 8 respectively acquire the optical signals transmitted in the sensing core 16 of the multi-core optical fiber 11.

In this embodiment, the structure, connection relationship and working principle of the remaining portions are the same as those of the first embodiment. The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments in accordance with the technical spirit of the present invention still belong to the present technology. Within the scope of protection of the program.

Claims

Claim

A multi-core optical fiber comprising an inner cladding (23) of an optical fiber and a core disposed in the inner cladding (23), characterized in that at least three cores are disposed on the inner cladding (23), one of the cores For the transmission core (15), the other core is the sensing core (16), each sensing core (16) is not less than the length of the transmission core (15), and has at least one sensing fiber The length of the core (16) is greater than the length of the transmission core (15).

The multi-core optical fiber according to claim 1, wherein the inner cladding layer (23) has an outer cladding layer (24), and the inner cladding layer (23) has a refractive index greater than that of the outer cladding layer (24). Index of refraction.

3. A multi-core optical fiber according to claim 2, characterized in that the inner cladding (23) has a non-circularly symmetrical defect cladding along a radial section of the multi-core optical fiber (11).

A multi-core optical fiber according to claim 1 or 3, characterized in that the sensing core (16) is arranged in a spiral shape in the inner cladding (23).

The multi-core optical fiber according to claim 4, wherein: said sensing core (16) is arranged in a spiral shape around the transmission core (15), and said transmission core (15) is located The axial center position of the spiral formed by the core (16).

6. A multi-core optical fiber according to claim 5, characterized in that said respective sensing cores (16) are at different distances from the transmission core (15).

A multi-core optical fiber according to claim 1, characterized in that at least two of said sensing cores (16) have different refractive index indices.

A multi-core optical fiber according to claim 1, characterized in that at least two of said sensing cores (16) have different core diameters.

9. A multi-core fiber-based sensing device comprising a control module (10), a light source module (12), a coupling module one (13), a photodetector module one (7) and a processing module (6), a control module (10) connecting with the light source module (12) and controlling the latter to emit an optical signal, the light source module (12) is connected to the coupling module (13), and the coupling module one (13) and one end of the multi-core optical fiber (11) Connecting, the multi-core fiber (11) has at least three cores disposed on the inner cladding (23), one of the cores is a transmission core (15), and the other core is a sensing core (16). At least one sensing core (16) has a different length than the length of the transmission core (15); the coupling module (13) is an optical signal a coupling module coupled only into the transmission core (15) in the multi-core fiber (11); at the other end of the multi-core fiber (11), connected to the photodetector module (7), the photodetector module (7) Simultaneously acquiring optical signals transmitted in each core of the multi-core optical fiber (11), and the photodetector module one (7) is connected to the processing module (6).

10. The multi-core fiber-based sensing device according to claim 9, wherein: the other end of the multi-core optical fiber (11) is connected to the coupling module two (9), and the coupling module two (9) Included in the at least two channels, each channel does not interfere with each other, at least two sensing cores (16) in the multi-core fiber (11) are respectively connected to two channels, and through the coupling module (9) respectively connected to the photodetector module one (7) and the photodetector module two (8); the photodetector module one

(7) Connect with the photodetector module 2 (8) and the processing module (6).

11. The multi-core optical fiber-based sensing device according to claim 9, wherein: the other end of the multi-core optical fiber (11) is connected to the coupling module three (4), and the coupling module is three (4) Included in the at least three channels, each channel does not interfere with each other, and at least two sensing cores (16) and transmission cores (15) in the multi-core fiber (11) are respectively connected to three channels And through the coupling module three (4) respectively connected to the photodetector module one (7), the photodetector module two (8) and the photodetector module three (5); the photodetector module one (7), light detection The module 2 (8) and the photodetector module 3 (5) are connected to the processing module (6).

12. A multi-core optical fiber-based sensing device according to claim 9, 10 or 11, characterized in that: the inner cladding (23) of the multi-core optical fiber (11) has an outer cladding (24), which is wrapped The refractive index of the layer (23) is greater than the refractive index of the outer cladding (24), and the cross section of the inner cladding (23) along the radial direction of the multi-core optical fiber (11) is a non-circular symmetric defect cladding.

13. A multi-core fiber-based sensing device according to claim 9, wherein: in said multi-core fiber (11), said sensing core (16) is arranged in a spiral shape in an inner package In the layer (23), the transmission core (15) is located at an axial center position of the spiral formed by the sensing core (16), and the respective sensing cores (16) are away from the transmission core (15). The distance is different.

14. A multi-core fiber-based sensing device comprising a control module (10), a light source module (12), a coupling module two (9), a photodetector module one (7) and a processing module (6), a control module (10) connecting with the light source module (12) and controlling the latter to emit an optical signal, the light source module (12) is connected with the coupling module two (9), and the coupling module two (9) and one end of the multi-core optical fiber (11) Connecting, the multi-core fiber (11) has at least three cores disposed on the inner cladding (23), wherein one core is a transmission core (15), the other core being a sensing core (16) having at least one sensing core (16) having a different length than the transmission core (15); said coupling module two (9) There are at least two channels, each channel does not interfere with each other, one of which is to make the optical signal from the light source module (12) only couple into the transmission core (15) in the multi-core fiber (11), and the other channel Multi-core fiber

The sensing core (16) of (11) is connected, and the transmitted optical signal in the sensing core (16) is connected to the photodetector module one (7) through the coupling module two (9), and the photodetector module one (7) Sensing the optical signal transmitted in the core (16), the photodetector module (7) is connected to the processing module (6);

The other end of (11) is provided with a light reflecting means (33).

15. A multi-core fiber-based sensing device according to claim 14, wherein: at least one of the coupling modules three (4) disposed at one end of the multi-core fiber (11) comprises at least three channels. Each channel does not interfere with each other, and at least two sensing cores (16) and transmission cores (15) in the multi-core fiber (11) are respectively connected to three channels, and through the coupling module three ( 4) respectively connected to the photodetector module one (7), the photodetector module two (8) and the light source module (12); the photodetector module one (7) and the photodetector module two (8) and the processing module (6) The photodetector module (7) and the photodetector module 2 (8) respectively acquire optical signals transmitted in the sensing core (16) of the multi-core optical fiber (11).

A multi-core fiber-based sensing device according to claim 14, wherein: said light reflecting means (33) is a fiber grating, a light reflecting mirror or an optical fiber containing bubbles.

17. A method of operating a sensing device based on a multi-core fiber, characterized in that:

1) comprising a sensing fiber (11) having a different length of the transmitting core (15) and the sensing core (16), and the control module (10) controlling the light source module (12) to emit a pulsed light signal, pulsed light The signal is transmitted through the coupler (13) into the transmission core (15) at one end of the multi-core fiber (11);

2) The pulsed optical signal is transmitted from one end of the multi-core optical fiber (11) to the other end in the transmission core (15), and is received by the photodetector module one (7) disposed at the other end of the multi-core optical fiber (11), The photodetector module (7) converts the pulsed optical signal into an electrical signal and transmits it to the processing module (6) _;

3) When somewhere on the multi-core fiber (11) is changed by the physical quantity to be measured, the optical signal transmitted in the transmission core (15) is partially coupled into two or more sensing cores ( 16) transmitted within each sensing core (16). Since the lengths of the transmitting core (15) and the sensing core (16) are different, the optical signal transmits at a different speed between the two, and then transmits Core (15) and sensing The optical signal in the core (16) arrives at the other end of the multi-core fiber (11) and is acquired by the photodetector module (7). The photodetector module (7) converts the acquired optical signal into an electrical signal. It is transmitted to the processing module (6), and the processing module (6) calculates the size and position of the physical quantity to be measured according to the size and time interval of the electrical signal, thereby completing the monitoring purpose.

18. A method of operating a multi-core fiber-based sensing device according to claim 17, wherein: said inner cladding (23) of said multi-core fiber (11) has an outer cladding (24), an inner cladding

The index of refraction of (23) is larger than the index of refraction of the outer cladding (24), and the cross section of the inner cladding (23) along the radial direction of the multi-core fiber (11) is a non-circularly symmetric defect cladding.

19. A method of operating a sensing device based on a multi-core fiber, characterized in that:

2) The pulsed optical signal is transmitted from one end of the multi-core optical fiber (11) to the other end in the transmission core (15), and a coupling module 2 (9) is disposed at the other end of the multi-core optical fiber (11), and the coupling is performed. Module two

(9) containing at least two channels, each channel not interfering with each other, at least two sensing cores (16) in the multi-core fiber (11) are respectively connected to two channels, and pass through The coupling module two (9) is respectively connected to the photodetector module one (7) and the photodetector module two (8); the photodetector module one

(7) and the photodetector module 2 (8) is connected to the processing module (6);

3) When somewhere on the multi-core fiber (11) is changed by the physical quantity to be measured, the optical signal transmitted in the transmission core (15) is partially coupled into two or more sensing cores ( 16) and transmitted within each sensing core (16), wherein at least two of the sensing optical cores (16) transmit optical signals respectively by the photodetector module one (7) and the photodetector module two (8) Obtaining, the two photodetector modules respectively convert the optical signal into an electrical signal and transmit it to the processing module (6), and the processing module (6) removes the change of the optical signal power according to the magnitude of the electrical signals of the two and the comparison between the two. The error is then passed through the time interval to calculate the size and position of the physical quantity to be measured, and the purpose of monitoring is completed.

20. A method of operating a multi-core fiber-based sensing device according to claim 19, wherein: said inner cladding (23) of said multi-core fiber (11) has an outer cladding (24), an inner cladding

The index of refraction of (23) is greater than the index of refraction of the outer cladding (24), and the cross section of the inner cladding (23) along the radial direction of the multi-core fiber (11) is a non-circularly symmetric defect cladding.

21. A method of operating a sensing device based on a multi-core fiber, characterized in that:

2) The pulsed optical signal is transmitted from one end of the multi-core optical fiber (11) to the other end in the transmission core (15), and a coupling module three (4) is disposed at the other end of the multi-core optical fiber (11), and the coupling is performed. Module three

(4) containing at least three channels, each channel not interfering with each other, at least two sensing cores (16) and transmission cores (15) in the multi-core fiber (11) respectively and three The channels are connected, and are connected to the photodetector module one (7), the photodetector module two (8) and the photodetector module three (5) through the coupling module three (4) respectively; the photodetector module one (7) , the photodetector module 2 (8) and the photodetector module 3 (5) are connected to the processing module (6);

3) When somewhere on the multi-core fiber (11) is changed by the physical quantity to be measured, the optical signal transmitted in the transmission core (15) is partially coupled into two or more sensing cores ( 16) and transmitted within each sensing core (16), wherein at least two sensing cores (16) and optical signals transmitted in the transmitting core (15) are respectively received by the photodetector module (7) The photodetector module 2 (8) and the photodetector module 3 (5) are obtained, and the three photodetector modules respectively convert the optical signal into an electrical signal and transmit it to the processing module (6), and the processing module (6) according to the light detection The size of the electrical signal transmitted by the module one (7) and the photodetector module (8) and the comparison between the two, eliminating the error introduced by the change of the optical signal power, and then passing the electricity transmitted by the photodetector module three (5) The time interval of the signal, thereby calculating the size and position of the physical quantity to be measured, and completing the purpose of monitoring.

22. The operating method of a multi-core optical fiber-based sensing device according to claim 21, wherein: the inner cladding (23) of the multi-core optical fiber (11) has an outer cladding layer (24), an inner cladding layer The index of refraction of (23) is greater than the index of refraction of the outer cladding (24), and the cross section of the inner cladding (23) along the radial direction of the multi-core fiber (11) is a non-circularly symmetric defect cladding.