An optical fiber monitoring device integrating fiber Bragg grating sensors

Abstract

The present invention provides an optical fiber monitoring device integrating fiber Bragg grating sensors, which includes a tunable laser, a processing module, a fusion detection module, and a plurality of fiber Bragg grating sensors arranged on an optical fiber, connected in sequence. By integrating the tunable laser with the fiber Bragg grating sensors, it can not only monitor the attenuation and breakpoints of the optical fiber, but also monitor physical quantities such as temperature and stress through the fiber Bragg grating sensors, occupying less optical fiber resources, and greatly reducing the complexity and cost of the device at the same time. The present invention can achieve cross decoupling of temperature and stress, avoid misjudgment of the state of the power optical cable network caused by cross sensitivity problems during multi-parameter measurement, and at the same time achieve unified processing for different detection optical wavelengths.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber sensing, and particularly relates to an optical fiber monitoring device integrating fiber Bragg grating sensors. Background Art

[0002] Optical fiber is an important communication medium, which has the advantages of low transmission loss and large communication bandwidth, and its performance and reliability directly affect the stable operation of the communication system. Optical fiber monitoring is a technical means for monitoring the attenuation and breakpoints of optical fibers. It

[0003] Optical fiber monitoring is a technology for monitoring the attenuation and breakpoints of communication optical fibers. Its technical principle is to emit an optical pulse to the measured optical fiber, and at the same time record the curve of the scattered or reflected signal intensity and the reception time of the pulse. The distance can be obtained through the reception time of the scattered or reflected signal and the propagation speed of light in the optical fiber, and finally the curve of the distance and the scattered or reflected signal intensity can be obtained. By analyzing this curve, the attenuation along the optical fiber, as well as events such as optical fiber breakpoints and fusion joints, can be known.

[0004] With the development of technology, in order to more comprehensively monitor the overall state of optical fibers, the monitoring requirements for physical quantities such as temperature and stress at key points along the optical fiber are increasing. The existing optical fiber monitoring technology can only effectively monitor the attenuation and breakpoints of optical fibers, and cannot simultaneously monitor the attenuation, breakpoints, temperature, stress and other physical quantities of optical fibers. To realize the monitoring of physical quantities such as temperature and stress, additional monitoring systems and monitoring lines are required, the implementation process is complex, it occupies a large amount of optical fiber resources, and the overall cost is high. Summary of the Invention

[0005] In order to overcome the deficiencies of large occupation of optical fiber resources and high cost in the above-mentioned existing technologies, the present invention provides an optical fiber monitoring device integrating fiber Bragg grating sensors, which includes a tunable laser, a processing module, a fusion detection module, and a plurality of fiber Bragg grating sensors arranged on the optical fiber, connected in sequence. The tunable laser is used to emit narrow-linewidth lasers of various wavelengths based on the requirements for monitoring the temperature and stress of the optical fiber, and is also used to emit narrow-linewidth lasers of a fixed wavelength based on the requirements for monitoring the attenuation and breakpoints of the optical fiber. When monitoring the temperature and stress of the optical fiber, the processing module is used to divide the narrow-linewidth lasers of various wavelengths into two detection lights and process the two detection lights. The fusion detection module is used to transmit a part of one of the detection lights to the optical fiber, and monitor the temperature and stress of the measured optical fiber through the fiber Bragg grating sensors. When monitoring the attenuation and breakpoints of the measured optical fiber, the processing module is used to divide the narrow-linewidth laser of the fixed wavelength into two detection lights and process the two detection lights. The fusion detection module is also used to transmit a part of one of the detection lights to the optical fiber to obtain the reflected light from the optical fiber, and fuse the processed other detection light, the remaining detection light of one of the detection lights, and the reflected light from the optical fiber to monitor the attenuation and breakpoints of the measured optical fiber. By integrating the tunable laser with the fiber Bragg grating sensors, not only can the attenuation and breakpoints of the optical fiber be monitored, but also physical quantities such as temperature and stress can be monitored, with small occupation of optical fiber resources, and at the same time, the complexity and cost of the device are greatly reduced.

[0006] In order to achieve the above-mentioned invention purpose, the present invention adopts the following technical solutions:

[0007] The present invention provides an optical fiber monitoring device integrating fiber Bragg grating sensors, which includes a tunable laser, a processing module, a fusion detection module, and a plurality of fiber Bragg grating sensors arranged on the optical fiber, connected in sequence;

[0008] The tunable laser is used to emit narrow-linewidth lasers of various wavelengths based on the requirements for monitoring the temperature and stress of the optical fiber, and is also used to emit narrow-linewidth lasers of a fixed wavelength based on the requirements for monitoring the attenuation and breakpoints of the optical fiber;

[0009] When monitoring the temperature and stress of the optical fiber, the processing module is used to divide the narrow-linewidth lasers of various wavelengths into two detection lights and process the two detection lights. The fusion detection module is used to transmit a part of one of the detection lights to the optical fiber, and monitor the temperature and stress of the measured optical fiber through the fiber Bragg grating sensors;

[0010] When monitoring the attenuation and break point of the optical fiber under test, the processing module is used to divide the narrow-linewidth laser with a fixed wavelength into two detection lights and process the two detection lights; the fusion detection module is also used to transmit a part of one of the detection lights to the optical fiber to obtain the reflected light from the optical fiber, and fuse the processed other detection light, the remaining detection light of one of the detection lights, and the reflected light from the optical fiber to monitor the attenuation and break point of the optical fiber under test.

[0011] The processing module includes a first wavelength division multiplexer, a first coupler, an optical amplifier, a second wavelength division multiplexer, and a first isolator;

[0012] The first wavelength division multiplexer is used to: screen the laser to obtain two detection lights, transmit one of the detection lights to the second wavelength division multiplexer, and transmit the other detection light to the first coupler;

[0013] The first coupler is used to: split the other laser into a Rayleigh local oscillator reference light and a Rayleigh detection light, transmit the Rayleigh local oscillator reference light to the fusion detection module, and at the same time transmit the Rayleigh detection light to the optical amplifier;

[0014] The optical amplifier is used to: amplify the modulated Rayleigh detection light and transmit the amplified Rayleigh detection light to the second wavelength division multiplexer;

[0015] The second wavelength division multiplexer is used to: fuse the laser from the first wavelength division multiplexer and the Rayleigh detection light from the optical amplifier;

[0016] The first isolator is used to: transmit the fused detection light to the fusion detection module.

[0017] The processing module further includes a modulator, which is located between the first coupler and the optical amplifier and is used to modulate the Rayleigh detection light.

[0018] The polarization scrambler is used to: perform polarization scrambling on the Rayleigh local oscillator reference light from the first coupler to obtain the polarization-scrambled Rayleigh local oscillator reference light;

[0019] The second isolator is used to: transmit the polarization-scrambled Rayleigh local oscillator reference light to the second coupler;

[0020] The second coupler is used to: receive the detection light from the first isolator, the fiber grating reflected light and the Rayleigh scattered light reflected from the fiber optic line, couple the polarization-scrambled Rayleigh local oscillator reference light and the Rayleigh scattered light, and transmit the coupled coherent Rayleigh scattered light to the photodetector;

[0021] The photodetector is used to: convert the coherent Rayleigh scattered light into an electrical signal.

[0022] The fiber optic monitoring device further includes a control module;

[0023] The control module is configured to: send a control signal to the tunable laser to control the tunable laser to emit a specified laser in the signal;

[0024] The control signal includes the wavelength, pulse width, and power of the laser.

[0025] The control module is further configured to send a pulse modulation signal to the modulator to control the modulator to modulate the Rayleigh probe light.

[0026] The fusion detection module further includes a detection and processing module;

[0027] The detection and processing module is configured to: demodulate the electrical signal.

[0028] The modulator is an acousto-optic modulator.

[0029] The optical amplifier is an erbium-doped optical amplifier.

[0030] The first isolator is further configured to: isolate the Rayleigh local oscillator reference light, fiber grating reflected light, and Rayleigh scattered light from the second coupler;

[0031] The second isolator is further configured to: isolate the fiber grating reflected light from the second coupler.

[0032] Compared with the closest prior art, the technical solution provided by the present invention has the following beneficial effects:

[0033] The optical fiber monitoring device integrating fiber Bragg grating sensors provided by the present invention includes a tunable laser, a processing module, a fusion detection module, and a plurality of fiber Bragg grating sensors arranged on the optical fiber, which are connected in sequence; the tunable laser is used to emit narrow-linewidth lasers of various wavelengths based on the requirements for monitoring the temperature and stress of the optical fiber, and is also used to emit narrow-linewidth lasers of a fixed wavelength based on the requirements for monitoring the attenuation and breakpoints of the optical fiber; when monitoring the temperature and stress of the optical fiber, the processing module is used to divide the narrow-linewidth lasers of various wavelengths into two detection lights and process the two detection lights; the fusion detection module is used to transmit a part of one of the detection lights to the optical fiber, and monitor the temperature and stress of the measured optical fiber through the fiber Bragg grating sensors; when monitoring the attenuation and breakpoints of the measured optical fiber, the processing module is used to divide the narrow-linewidth laser of the fixed wavelength into two detection lights and process the two detection lights; the fusion detection module is further used to transmit a part of one of the detection lights to the optical fiber to obtain the reflected light from the optical fiber, and fuse the processed other detection light, the remaining detection light of one of the detection lights, and the reflected light from the optical fiber to monitor the attenuation and breakpoints of the measured optical fiber. By integrating the tunable laser with the fiber Bragg grating sensors, not only can the attenuation and breakpoints of the optical fiber be monitored, but also the monitoring of physical quantities such as temperature and stress can be realized, occupying less optical fiber resources, and at the same time greatly reducing the complexity and cost of the device;

[0034] In the present invention, a plurality of fiber Bragg grating sensors are arranged on the optical fiber. The accuracy of physical quantities such as temperature and stress monitored by the fiber Bragg grating sensors is high, and high-precision multi-parameter measurement of the attenuation, temperature, stress, disturbance, etc. along the optical fiber can be realized, thereby providing accurate data support for the evaluation of the entire life cycle of the optical fiber and the status monitoring of important monitoring points along its line;

[0035] In the present invention, the second coupler is used to couple the Rayleigh local oscillator reference light and the Rayleigh scattered light after polarization scrambling to obtain coherent Rayleigh scattered light, and the detection and processing module is used to demodulate the electrical signals from the photoelectric sensor, so that the cross-decoupling of temperature and stress can be realized, and the misjudgment of the state of the power optical cable network caused by the cross-sensitivity problem during multi-parameter measurement can be avoided;

[0036] In the present invention, the control module sends control signals such as the wavelength, pulse width, and power of the laser to the tunable laser, and the tunable laser emits laser according to the control signals. At the same time, the control module sends a pulse modulation signal to the modulator, and the modulator modulates the Rayleigh detection light from the first coupler according to the pulse modulation signal, realizing the simultaneous control of the tunable laser and the modulator.

[0037] The present invention uses a first wavelength division multiplexer to separate the laser into Rayleigh detection light and FBG detection light, and uses a second coupler to couple the Rayleigh local oscillator reference light and the Rayleigh scattered light. When the detection light is the Rayleigh detection light, coherent detection is achieved through the second coupler; when the detection light is the Rayleigh scattered light, the second coupler has no effect on the scattered / FBG reflected light, realizing unified processing for different detection light wavelengths. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a structural diagram of an optical fiber monitoring device integrating an optical fiber grating sensor in an embodiment of the present invention;

[0039] Figure 2 is another structural diagram of an optical fiber monitoring device integrating an optical fiber grating sensor in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The present invention will be further described in detail below with reference to the accompanying drawings.

[0041] The FBG optical sensor, namely the fiber Bragg grating sensor, is abbreviated as the fiber grating sensor. It is a fiber sensor with the highest frequency of use and the widest range. This sensor can change the wavelength of the reflected light wave according to the changes in environmental temperature and / or strain. The fiber Bragg grating is formed by exposing a small section of photosensitive optical fiber to a light wave with a periodic intensity distribution through holographic interference or phase mask method. In this way, the refractive index of the optical fiber will be permanently changed according to the intensity of the irradiated light wave. The periodic change in the refractive index caused by this method is called the fiber Bragg grating.

[0042] An embodiment of the present invention provides an optical fiber monitoring device integrating an optical fiber grating sensor, such as Figure 1 , including a tunable laser, a processing module, a fusion detection module, and a plurality of optical fiber grating sensors arranged on the optical fiber, which are connected in sequence.

[0043] The tunable laser is used to emit narrow-linewidth lasers of various wavelengths based on the requirements for monitoring the temperature and stress of the optical fiber, and is also used to emit narrow-linewidth lasers of a fixed wavelength based on the requirements for monitoring the attenuation and breakpoints of the optical fiber;

[0044] When monitoring the temperature and stress of the optical fiber, the processing module is used to divide the narrow-linewidth lasers of various wavelengths into two paths of detection light and process the two paths of detection light; the fusion detection module is used to transmit a part of the detection light of one path of detection light to the optical fiber, and monitor the temperature and stress of the optical fiber under test through the optical fiber grating sensor;

[0045] When monitoring the attenuation and break point of the fiber under test, the processing module is used to divide the narrow linewidth laser with a fixed wavelength into two detection lights and process the two detection lights; the fusion detection module is also used to transmit a part of one of the detection lights to the optical fiber to obtain the reflected light from the optical fiber, and fuse the processed other detection light, the remaining detection light of one of the detection lights, and the reflected light from the optical fiber to monitor the attenuation and break point of the fiber under test.

[0046] As Figure 2 shown, the processing module includes a first wavelength division multiplexer, a first coupler, an optical amplifier, a second wavelength division multiplexer, and a first isolator;

[0047] The first wavelength division multiplexer is used to: screen the C-band narrow linewidth laser output by the tunable laser in steps of 1 pm to obtain two detection lights, transmit one of the detection lights (i.e., the laser with other wavelengths except the 1550 nm wavelength) to the second wavelength division multiplexer, and transmit the other detection light (the laser with a wavelength of 1550 nm) to the first coupler;

[0048] The first coupler is used to: split the other laser into a Rayleigh local oscillator reference light and a Rayleigh detection light, transmit the Rayleigh local oscillator reference light to the fusion detection module, and at the same time transmit the Rayleigh detection light to the optical amplifier;

[0049] The optical amplifier is used to: amplify the modulated Rayleigh detection light and transmit the amplified Rayleigh detection light to the second wavelength division multiplexer;

[0050] The second wavelength division multiplexer is used to: fuse the laser from the first wavelength division multiplexer and the Rayleigh detection light from the optical amplifier;

[0051] The first isolator is used to: transmit the fused detection light to the fusion detection module.

[0052] The processing module further includes a modulator, which is located between the first coupler and the optical amplifier and is used to modulate the Rayleigh detection light.

[0053] The fusion detection module includes a polarization scrambler, a second isolator, a second coupler, and a photodetector;

[0054] The polarization scrambler is used to: perform polarization scrambling on the Rayleigh local oscillator reference light from the first coupler to obtain the polarization-scrambled Rayleigh local oscillator reference light;

[0055] The second isolator is used to: transmit the polarization-scrambled Rayleigh local oscillator reference light to the second coupler;

[0056] The second coupler is configured to: receive the probe light from the first isolator, the fiber grating reflected light and the Rayleigh scattered light reflected from the optical fiber line, couple the Rayleigh local oscillator reference light and the Rayleigh scattered light after polarization scrambling, and transmit the coupled coherent Rayleigh scattered light to a photodetector;

[0057] The photodetector is configured to: convert the coherent Rayleigh scattered light into an electrical signal.

[0058] The optical fiber monitoring device further includes a control module;

[0059] The control module is configured to: send a control signal to the tunable laser to control the specified laser in the signal emitted by the tunable laser; the control signal includes the wavelength, pulse width and power of the laser.

[0060] The control module is further configured to send a pulse modulation signal to the modulator to control the modulator to modulate the Rayleigh probe light.

[0061] The fusion detection module further includes a detection and processing module;

[0062] The detection and processing module is configured to: demodulate the electrical signal.

[0063] The modulator is an acousto-optic modulator;

[0064] The optical amplifier is an erbium-doped optical amplifier.

[0065] Due to the bi-directional transmission of the optical path and the self-characteristics of the second coupler, the first isolator is used to isolate the Rayleigh local oscillator reference light, the fiber grating reflected light and the Rayleigh scattered light from the second coupler; the second isolator is used to isolate the fiber grating reflected light from the second coupler.

[0066] In the embodiment of the present invention, the first wavelength division multiplexer is used to separate the C-band narrow linewidth laser into Rayleigh probe light with a wavelength of 1550 nm and FBG probe light (i.e., other lasers in the C-band narrow linewidth laser except the Rayleigh probe light with a wavelength of 1550 nm), and the second coupler is used to couple the Rayleigh local oscillator reference light and the Rayleigh scattered light. When the probe light is the Rayleigh probe light with a wavelength of 1550 nm, coherent detection is achieved through the second coupler; when the probe light is other wavelengths in the C-band, the second coupler has no effect on the scattered / FBG reflected light, realizing unified processing for different probe light wavelengths.

[0067] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Those of ordinary skill in the art can still modify or equivalently replace the specific implementation manners of the present invention with reference to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. An optical fiber monitoring device integrating fiber Bragg grating sensors, characterized in that, It includes a tunable laser, a processing module, a fusion detection module, and multiple fiber Bragg grating sensors disposed on an optical fiber, which are connected in sequence; The tunable laser is used to emit narrow-linewidth lasers of various wavelengths based on the requirements for monitoring the temperature and stress of the optical fiber, and is also used to emit narrow-linewidth lasers of a fixed wavelength based on the requirements for monitoring the attenuation and breakpoints of the optical fiber; When monitoring the temperature and stress of the optical fiber, the processing module is used to divide the narrow-linewidth lasers of various wavelengths into two detection lights and process the two detection lights; The fusion detection module is used to transmit a part of one of the detection lights to the optical fiber, and monitor the temperature and stress of the measured optical fiber through the fiber Bragg grating sensor; When monitoring the attenuation and breakpoints of the measured optical fiber, the processing module is used to divide the narrow-linewidth laser of the fixed wavelength into two detection lights and process the two detection lights; the fusion detection module is also used to transmit a part of one of the detection lights to the optical fiber to obtain the reflected light from the optical fiber, and fuse the processed other detection light, the remaining detection light of one of the detection lights, and the reflected light from the optical fiber to monitor the attenuation and breakpoints of the measured optical fiber; The processing module includes a first wavelength division multiplexer, a first coupler, an optical amplifier, a second wavelength division multiplexer, and a first isolator; The first wavelength division multiplexer is used to: screen the laser to obtain two detection lights, transmit one of the detection lights to the second wavelength division multiplexer, and transmit the other detection light to the first coupler; The first coupler is used to: split the other laser into a Rayleigh local oscillator reference light and a Rayleigh detection light, transmit the Rayleigh local oscillator reference light to the fusion detection module, and at the same time transmit the Rayleigh detection light to the optical amplifier; The optical amplifier is used to: amplify the modulated Rayleigh detection light and transmit the amplified Rayleigh detection light to the second wavelength division multiplexer; The second wavelength division multiplexer is used to: fuse the laser from the first wavelength division multiplexer and the Rayleigh detection light from the optical amplifier; The first isolator is used to: transmit the fused detection light to the fusion detection module; The fusion detection module includes a polarization scrambler, a second isolator, a second coupler, and a photodetector; The polarization scrambler is used to: perform polarization scrambling on the Rayleigh local oscillator reference light from the first coupler to obtain the polarization-scrambled Rayleigh local oscillator reference light; The second isolator is used to: transmit the polarization-scrambled Rayleigh local oscillator reference light to the second coupler; The second coupler is used to: receive the detection light from the first isolator, the fiber Bragg grating reflected light and Rayleigh scattered light reflected from the optical fiber line, couple the polarization-scrambled Rayleigh local oscillator reference light and the Rayleigh scattered light, and transmit the coupled coherent Rayleigh scattered light to the photodetector; The photodetector is used to: convert the coherent Rayleigh scattered light into an electrical signal.

2. The optical fiber monitoring device integrating an optical fiber grating sensor according to claim 1, characterized in that The processing module further includes a modulator, which is located between the first coupler and the optical amplifier and is used to modulate the Rayleigh detection light.

3. The optical fiber monitoring device integrating an optical fiber grating sensor according to claim 2, characterized in that, The optical fiber monitoring device further includes a control module; The control module is configured to: send a control signal to the tunable laser to control the emission of a specified laser in the signal emitted by the tunable laser; The control signal includes the wavelength, pulse width, and power of the laser.

4. The optical fiber monitoring device integrating an optical fiber grating sensor according to claim 3, characterized in that, The control module is further configured to send a pulse modulation signal to the modulator to control the modulator to modulate the Rayleigh probe light.

5. The optical fiber monitoring device integrating an optical fiber grating sensor according to claim 1, characterized in that, The fusion detection module further includes a detection and processing module; The detection and processing module is configured to: demodulate the electrical signal.

6. The optical fiber monitoring device integrating an optical fiber grating sensor according to claim 2, characterized in that, The modulator is an acousto-optic modulator.

7. The optical fiber monitoring device integrating an optical fiber grating sensor according to claim 1, characterized in that, The optical amplifier is an erbium-doped optical amplifier.

8. The optical fiber monitoring device integrating an optical fiber grating sensor according to claim 1, characterized in that, The first isolator is further configured to: isolate the Rayleigh local oscillator reference light, the fiber grating reflected light, and the Rayleigh scattered light from the second coupler.

9. The fiber optic monitoring device integrating a fiber Bragg grating sensor according to claim 1, characterized in that, The second isolator is further configured to: isolate the fiber grating reflected light from the second coupler.

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