CN117346879A - Long-distance optical fiber distributed acoustic wave sensing device based on repeater - Google Patents

Long-distance optical fiber distributed acoustic wave sensing device based on repeater Download PDF

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CN117346879A
CN117346879A CN202311330495.XA CN202311330495A CN117346879A CN 117346879 A CN117346879 A CN 117346879A CN 202311330495 A CN202311330495 A CN 202311330495A CN 117346879 A CN117346879 A CN 117346879A
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optical fiber
distributed acoustic
sensing
wavelength division
repeater
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杨悦
徐汉锋
钟一博
吴超钒
宛立君
李东明
葛辉良
谢勇
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715 Research Institute Of China Shipbuilding Corp
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715 Research Institute Of China Shipbuilding Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06754—Fibre amplifiers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
    • H01S3/1123—Q-switching
    • H01S3/115—Q-switching using intracavity electro-optic devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)

Abstract

The invention relates to a long-distance optical fiber distributed acoustic wave sensing device based on a repeater, which consists of a first optical fiber distributed acoustic sensing system, a second optical fiber distributed acoustic sensing system, a front section sensing optical fiber, a rear section sensing optical fiber and a repeater; the repeater is embedded in the joint of the front section sensing optical fiber and the rear section sensing optical fiber and is respectively connected with the front section sensing optical fiber and the rear section sensing optical fiber, and is used for amplifying light pulses transmitted by the first optical fiber distributed acoustic sensing system and the second optical fiber distributed acoustic sensing system in a long distance and amplifying and outputting generated interference light signals; the first optical fiber distributed acoustic sensing system is connected with the head end of the front section of sensing optical fiber, and the tail end of the rear section of sensing optical fiber is connected with the second optical fiber distributed acoustic sensing system; the first optical fiber distributed acoustic sensing system outputs amplified pulse excitation light to be input into the front-section sensing optical fiber to realize the detection of the front half part of the front-section sensing optical fiber. According to the invention, the repeater is added in the sensing optical fiber, so that the sensing optical fiber can be detected in a segmented manner and the pulse light can be amplified, and the sensing distance of the distributed optical fiber can be increased.

Description

Long-distance optical fiber distributed acoustic wave sensing device based on repeater
Technical field:
the invention belongs to the technical field of optical fiber distributed sensing, and particularly relates to a long-distance optical fiber distributed acoustic wave sensing device based on a repeater.
The background technology is as follows:
the distributed optical fiber sensor has been widely used in various fields due to the characteristics of long sensing distance, distributed detection, multiple measurable parameters, high sensitivity and the like. Among them, all-fiber distributed acoustic wave sensor (FODAS) based on phase sensitive optical time domain reflectometer (Φ -OTDR) has been successfully applied in the fields of petroleum exploration, geological structure detection, pipeline safety monitoring, underwater sound detection, etc. in recent years. The DAS based on phi-OTDR uses an optical fiber as a sensitive element and a transmission medium, and realizes the continuous distributed detection of external acoustic wave information along the optical fiber through the phase change of backward Rayleigh scattered light in the optical fiber. Because the sensing optical fiber has transmission loss, the power of the detection light and the backward Rayleigh scattering light can be gradually attenuated in the transmission process in the optical fiber, and when the power of the incoming optical fiber is too high, nonlinear effect can occur in the optical fiber, so that the energy of the detection signal light is greatly transferred and consumed, and the sensing signal-to-noise ratio is reduced, and therefore, the distributed acoustic wave sensing with a longer distance is difficult to realize.
The system comprises single-end or double-end pumping amplification and remote pumping erbium-doped fiber, so that the sensing distance is prolonged, but the remote pumping erbium-doped fiber and double-end pumping amplification mixed technology is needed for realizing the long-distance sensing of more than hundred kilometers, the gain of the whole-process optical path signal is uneven, the signal to noise ratio is poor, and the sensing distance of 140km at the longest is realized. For example, a relay amplifying device for realizing long-distance distributed optical fiber sensing is disclosed in chinese patent application publication No. CN106788752 a, and the relay amplifying device is composed of an optical power amplifier, a pre-optical amplifier, a distributed optical amplifier, a filter and a circulator to amplify strong excitation light and weak sensing light signals, but a Φ -OTDR system needs one relay amplifying device every 50km of optical fiber, and two relay amplifying devices are needed to realize 150km of sensing distance, and the types of devices needed by the relay amplifying device are many.
Therefore, further improvements are needed.
The invention comprises the following steps:
the invention aims to solve the technical problem of providing a long-distance optical fiber distributed acoustic wave sensing device based on a repeater.
The invention provides a long-distance optical fiber distributed acoustic wave sensing device based on a repeater, which consists of a first optical fiber distributed acoustic sensing system, a second optical fiber distributed acoustic sensing system, a front section sensing optical fiber, a rear section sensing optical fiber and a repeater; wherein,
the repeater is embedded in the joint of the front section sensing optical fiber and the rear section sensing optical fiber and is connected with the front section sensing optical fiber and the rear section sensing optical fiber, and is used for amplifying light pulses transmitted by the first optical fiber distributed acoustic sensing system and the second optical fiber distributed acoustic sensing system in a long distance and amplifying and outputting generated interference light signals;
the first optical fiber distributed acoustic sensing system is connected with the head end of the front section of sensing optical fiber, and the tail end of the rear section of sensing optical fiber is connected with the second optical fiber distributed acoustic sensing system; the first optical fiber distributed acoustic sensing system outputs amplified pulse excitation light to be input into a front section sensing optical fiber to realize the detection of the front half part of the front section sensing optical fiber, and simultaneously outputs the pulse excitation light to be remotely transmitted to a repeater through the front section sensing optical fiber and then to be input into the tail end of the front section sensing optical fiber after being amplified by the repeater to realize the detection of the rear half part of the front section sensing optical fiber;
the second optical fiber distributed acoustic sensing system outputs the amplified pulse excitation light to the tail end of the rear-section sensing optical fiber to realize the detection of the rear half part of the rear-section sensing optical fiber, and simultaneously outputs the pulse excitation light to be remotely transmitted to the repeater through the rear-section sensing optical fiber and amplified by the repeater to be input to the head end of the rear-section sensing optical fiber to realize the detection of the front half part of the rear-section sensing optical fiber.
Preferably, the first optical fiber distributed acoustic sensing system and the second optical fiber distributed acoustic sensing system respectively comprise a first light source, a first coupler, a second light source, a second coupler, a first wavelength division multiplexer, an optical modulator, an arbitrary waveform generator, a first optical amplifier, a second wavelength division multiplexer, a first circulator, a first pump, a third wavelength division multiplexer, a third coupler, a fourth coupler, a first photoelectric detection module, a second photoelectric detection module and a signal demodulation module which are sequentially arranged on an optical path; wherein,
the output end of the first light source is connected with the input end of the first coupler, the output end of the second light source is connected with the input end of the second coupler, one of the output ends of the first coupler and the second coupler is respectively connected with the first input end and the second input end of the first wavelength division multiplexer, the output end of the first wavelength division multiplexer is connected with the input end of the optical modulator, the output end of the arbitrary waveform generator is connected with the modulation input end of the optical modulator, the output end of the optical modulator is connected with the input end of the first optical amplifier, the output end of the first optical amplifier is connected with the input end of the second wavelength division multiplexer, the second output end of the second wavelength division multiplexer is connected with the input end of the first circulator, one end of the output end of the first circulator is connected with the second input end of the third wavelength division multiplexer, the other output end of the first pump is connected with the one input end of the third wavelength division multiplexer, the output end of the third wavelength division multiplexer is connected with the front-section sensing, the other output end of the second pump is connected with the other output end of the third wavelength division multiplexer, the other output end of the second pump is connected with the second input end of the second optical detector is connected with the second optical detector module, and the second optical detector is connected with the second optical detector module.
Preferably, the repeater is composed of a second pump, a fourth wavelength division multiplexer, a second circulator, a fifth coupler, a second optical amplifier, a third pump, a fifth wavelength division multiplexer, a third circulator, a sixth coupler and a third optical amplifier which are sequentially arranged, a front-section sensing optical fiber which is connected with the third wavelength division multiplexer in the first optical fiber distributed acoustic sensing system is connected with the output end of the fourth wavelength division multiplexer, the output end of the second pump is connected with one input end of the fourth wavelength division multiplexer, one output end of the second circulator is connected with the other input end of the fourth wavelength division multiplexer, the other output end of the second circulator is connected with one input end of the fifth coupler, and the output end of the fifth coupler is connected with the input end of the second optical amplifier; the back section sensing optical fiber connected from the third wavelength division multiplexer in the second optical fiber distributed acoustic sensing system is connected with the output end of the fifth wavelength division multiplexer, the output end of the third pump is connected with one input end of the fifth wavelength division multiplexer, one output end of the third circulator is connected with the other input end of the fifth wavelength division multiplexer, the other output end of the third circulator is connected with one input end of the sixth coupler, and the output end of the sixth coupler is connected with the input end of the third optical amplifier.
Preferably, one output end of the second wavelength division multiplexer in the first optical fiber distributed acoustic sensing system is remotely transmitted to the input end of the second circulator of the repeater through the front section of sensing optical fiber; the other output end of the first coupler in the first optical fiber distributed acoustic sensing system is remotely transmitted to the other input end of the fifth coupler of the repeater through the front section of sensing optical fiber; one output end of a second wavelength division multiplexer in the second optical fiber distributed acoustic sensing system is remotely transmitted to the input end of a third circulator of the repeater through a rear section sensing optical fiber, and the other output end of a first coupler in the second optical fiber distributed acoustic sensing system is remotely transmitted to the other input end of a sixth coupler of the repeater through the rear section sensing optical fiber.
Preferably, the output end of the second optical amplifier in the repeater is remotely transmitted to the input end of the fourth coupler in the first optical fiber distributed acoustic sensing system through the front-section sensing optical fiber; the output end of the third optical amplifier in the repeater is remotely transmitted to the input end of the fourth coupler in the second optical fiber distributed acoustic sensing system through the rear sensing optical fiber.
Preferably, the first light source and the second light source in the first optical fiber distributed acoustic sensing system and the second optical fiber distributed acoustic sensing system are light sources with two different central wavelengths, and are used for respectively detecting the front half part and the rear half part of each section of sensing optical fiber, so that interference generated when two beams of detection pulse light are transmitted in the sensing optical fiber is avoided, and detection is influenced.
Preferably, the first wavelength division multiplexer and the second wavelength division multiplexer in the first optical fiber distributed acoustic sensing system and the second optical fiber distributed acoustic sensing system are respectively used for combining and de-combining the light waves with two wavelengths.
Preferably, any waveform generator in the first optical fiber distributed acoustic sensing system and the second optical fiber distributed acoustic sensing system is used for generating a pulse modulation signal to drive the optical modulator.
Preferably, the first photoelectric detection module and the second photoelectric detection module in the first optical fiber distributed acoustic sensing system and the second optical fiber distributed acoustic sensing system are light balance detection modules, and are used for eliminating direct current influence in interference signals.
Further, the first pump, the second pump and the third pump are used for generating pump light to provide gain for the detection pulse light and prolong the sensing distance.
As a further technical scheme, when the sensing optical fiber is affected by the sound pressure signal, the length of the sensing optical fiber is changed, so that the phase of backward rayleigh scattered light in the sensing optical fiber is changed, and therefore, the backward rayleigh scattered light and local continuous light generate a phase difference to form interference fringes. The demodulation module demodulates the interference signal to obtain a corresponding acoustic signal.
Compared with the prior art, the invention has the following advantages:
in order to realize long-distance distributed optical fiber acoustic sensing, the invention adds the repeater among the sensing optical fibers, divides the sensing optical fibers into two sections for independent detection, reduces the detection distance of the detection pulse light in the optical fiber distributed acoustic sensing system, and effectively prolongs the sensing distance of the optical fiber distributed acoustic sensing system. The repeater provides enough gain for the detection pulse light through pumping distributed amplification so as to overcome the optical fiber loss, change the power distribution of the detection pulse light along the sensing optical fiber, improve the detection pulse light power at the lower part of the detection pulse light power, and further realize long-distance sensing. The optical cable embedded into the repeater is fused with the distributed optical fiber acoustic sensing technology, so that the remote monitoring of the positioning type long-distance distributed optical fiber acoustic sensor is realized.
And the invention injects the detection pulse light into one end of each section of sensing optical fiber after the pump distributed amplification, and simultaneously transmits the detection pulse light to the repeater in a long distance through the transmission optical fiber, and injects the detection pulse light into the other end of each section of sensing optical fiber after the pump distributed amplification, so as to segment each section of sensing optical fiber again, thereby realizing the simultaneous segmented detection of the two ends. By combining single-ended pumping distributed amplification and sensing optical fiber segmented detection, the detection pulse optical power at the lower part of the detection pulse optical power is improved, and further the flatness of the whole-course optical path signal gain is improved, so that acoustic sensing with higher signal-to-noise ratio is realized.
Meanwhile, the distributed optical fiber acoustic sensing system adopts a coherent heterodyne detection mode, and can extract phase information at different positions by combining a corresponding demodulation algorithm, so that the distributed optical fiber acoustic sensing system is relatively simple in structure and easy to realize. Meanwhile, the heterodyne detection mode can detect weak acoustic signals, the signal-to-noise ratio of the system is high, the sensitivity is high, and long-distance sensing can be realized.
Description of the drawings:
FIG. 1 is a schematic diagram of a long-distance optical fiber distributed acoustic wave sensing link based on a repeater;
fig. 2 is a schematic structural diagram of a long-distance optical fiber distributed acoustic wave sensor device based on a repeater according to the present invention.
In the figure, 1, a first light source, 2, a second light source, 3, a first coupler, 4, a second coupler, 5, a first wavelength division multiplexer, 6, an optical modulator, 7, an arbitrary waveform generator, 8, a first optical amplifier, 9, a second wavelength division multiplexer, 10, a first circulator, 11, a first pump, 12, a third wavelength division multiplexer, 13, a third coupler, 14, a fourth coupler, 15, a first photoelectric detection module, 16, a second photoelectric detection module, 17, a signal demodulation module, 18-1, a first optical fiber distributed acoustic sensor system, 18-2, a second optical fiber distributed acoustic sensor system, 19, a front-stage sensing optical fiber, 20, a fourth wavelength division multiplexer, 21, a second pump, 22, a second circulator, 23, a fifth coupler, 24, a second optical amplifier, 25, a third circulator, 26, a fifth wavelength division multiplexer, 27, a third pump, 28, a sixth coupler, 29, a third optical amplifier, 30, 31, a rear-stage optical fiber sensor system.
The specific embodiment is as follows:
the invention is further described in terms of specific embodiments in conjunction with the following drawings:
as shown in fig. 1-2, the present embodiment provides a repeater-based long-distance optical fiber distributed acoustic wave sensing device, which is composed of two FODAS systems, two sections of sensing optical fibers and a repeater 30; the two FODAS systems are respectively a first optical fiber distributed acoustic sensing system 18-1 and a second optical fiber distributed acoustic sensing system 18-2; the two sections of sensing optical fibers are respectively a front section of sensing optical fiber 19 and a rear section of sensing optical fiber 31.
The repeater 30 is embedded in the junction of the two sensing fibers to connect the front sensing fiber 19 and the rear sensing fiber 31 for amplifying the light pulses transmitted from the first optical fiber distributed acoustic sensor system 18-1 and the second optical fiber distributed acoustic sensor system 18-2 and amplifying the generated interference light signals.
The first optical fiber distributed acoustic sensing system 18-1 is connected with the head end of the front section sensing optical fiber 19, the tail end of the rear section sensing optical fiber 31 is connected with the second optical fiber distributed acoustic sensing system 18-2, the first optical fiber distributed acoustic sensing system 18-1 outputs amplified pulse excitation light to be input into the front half part of the front section sensing optical fiber 19 to realize detection of the front half part of the front section sensing optical fiber, and meanwhile, the output pulse excitation light is remotely transmitted to the repeater 30 through the front section sensing optical fiber 19 and is amplified by the repeater 30 and then is input into the tail end of the front section sensing optical fiber 19 to realize detection of the rear half part of the front section sensing optical fiber;
the second optical fiber distributed acoustic sensing system 18-2 outputs the amplified pulse excitation light to the tail end of the rear-section sensing optical fiber 31 to realize the detection of the rear half part of the rear-section sensing optical fiber, and simultaneously outputs the pulse excitation light to the repeater 30 through the rear-section sensing optical fiber 31 for long distance transmission, and the pulse excitation light is amplified by the repeater 30 and then is input to the head end of the rear-section sensing optical fiber 31 to realize the detection of the front half part of the rear-section sensing optical fiber.
In this embodiment, the lengths of the front sensing fiber 19 and the rear sensing fiber 31 are 100km.
The first optical fiber distributed acoustic sensing system and the second optical fiber distributed acoustic sensing system respectively comprise a first light source 1, a first coupler 3, a second light source 2, a second coupler 4, a first wavelength division multiplexer 5, an optical modulator 6, an arbitrary waveform generator 7, a first optical amplifier 8, a second wavelength division multiplexer 9, a first circulator 10, a first pump 11, a third wavelength division multiplexer 12, a third coupler 13, a fourth coupler 14, a first photoelectric detection module 15, a second photoelectric detection module 16 and a signal demodulation module 17 which are sequentially arranged on an optical path; wherein,
the output end of the first light source 1 is connected with the input end of the first coupler 3, the output end of the second light source 2 is connected with the input end of the second coupler 4, one of the output ends of the first coupler 3 and the second coupler 4 is respectively connected with the first input end and the second input end of the first wavelength division multiplexer 5, the output end of the first wavelength division multiplexer 5 is connected with the input end of the optical modulator 6, the output end of the arbitrary waveform generator 7 is connected with the modulation input end of the optical modulator 6, the output end of the optical modulator 6 is connected with the input end of the first optical amplifier 8, the output end of the first optical amplifier 8 is connected with the input end of the second wavelength division multiplexer 9, the second output end of the second wavelength division multiplexer 9 is connected with the input end of the first circulator 10, one end of the output end of the first circulator 10 is connected with the second input end of the third wavelength division multiplexer 12, the other output end of the first circulator 10 is connected with one input end of the third coupler 13, the output end of the first pump 11 is connected with one input end of the third wavelength division multiplexer 12, the output end of the third wavelength division multiplexer 12 is connected with the front-section sensing optical fiber 19, the other output end of the second coupler 4 is connected with the other input end of the third coupler 13, the two output ends of the third coupler 13 are connected with the first photoelectric detection module 15, the two output ends of the fourth coupler 14 are connected with the second photoelectric detection module 16, and the output ends of the first photoelectric detection module 15 and the second photoelectric detection module 16 are connected with the input end of the signal demodulation module 17.
The repeater consists of a second pump 21, a fourth wavelength division multiplexer 20, a second circulator 22, a fifth coupler 23, a second optical amplifier 24, a third pump 27, a fifth wavelength division multiplexer 26, a third circulator 25, a sixth coupler 28 and a third optical amplifier 29 which are sequentially arranged, a front-stage sensing optical fiber 19 which is connected with a third wavelength division multiplexer 12 in the first optical fiber distributed acoustic sensing system is connected with the output end of the fourth wavelength division multiplexer 20, the output end of the second pump 21 is connected with one input end of the fourth wavelength division multiplexer 20, one output end of the second circulator 22 is connected with the other input end of the fourth wavelength division multiplexer 20, the other output end of the second circulator 22 is connected with one input end of the fifth coupler 23, and the output end of the fifth coupler 23 is connected with the input end of the second optical amplifier 24; the rear sensing optical fiber 31 connected from the third wavelength division multiplexer 12 in the second optical fiber distributed acoustic sensing system is connected with the output end of the fifth wavelength division multiplexer 26, the output end of the third pump 27 is connected with one input end of the fifth wavelength division multiplexer 26, one output end of the third circulator 25 is connected with the other input end of the fifth wavelength division multiplexer 26, the other output end of the third circulator 25 is connected with one input end of the sixth coupler 28, and the output end of the sixth coupler 28 is connected with the input end of the third optical amplifier 29.
As a preferred embodiment, one output end of the second wavelength division multiplexer 9 inside the first optical fiber distributed acoustic sensing system is remotely transmitted to the input end of the second circulator 22 of the repeater through the front-stage sensing optical fiber 19; the other output end of the first coupler 3 in the first optical fiber distributed acoustic sensing system is remotely transmitted to the other input end of the fifth coupler 23 of the repeater through the front section of sensing optical fiber 19; one output end of the second wavelength division multiplexer 9 in the second optical fiber distributed acoustic sensing system is remotely transmitted to the input end of the third circulator 25 of the repeater through the rear-section sensing optical fiber 31, and the other output end of the first coupler 3 in the second optical fiber distributed acoustic sensing system is remotely transmitted to the other input end of the sixth coupler 28 of the repeater through the rear-section sensing optical fiber 31.
As a preferred embodiment, the output end of the second optical amplifier 24 inside the repeater is remotely transmitted to the input end of the fourth coupler 14 inside the first optical fiber distributed acoustic sensing system through the front-end sensing optical fiber 19; the output end of the third optical amplifier 29 in the repeater is remotely transmitted to the input end of the fourth coupler 14 in the second optical fiber distributed acoustic sensing system through the rear sensing optical fiber 31.
Specifically, in this embodiment, the device includes a first optical fiber distributed acoustic sensing system 18-1, a second optical fiber distributed acoustic sensing system 18-2, a front section sensing optical fiber 19 with a length of 100km, a repeater 30, and a rear section sensing optical fiber 31 with a length of 100km as well; the first optical fiber distributed acoustic sensing system 18-1 and the second optical fiber distributed acoustic sensing system 18-2 are composed of a first light source 1, a second light source 2, a first coupler 3, a second coupler 4, a first wavelength division multiplexer 5, an optical modulator 6, an arbitrary waveform generator 7, a first optical amplifier 8, a second wavelength division multiplexer 9, a first circulator 10, a first pump 11, a third wavelength division multiplexer 12, a third coupler 13, a fourth coupler 14, a first photoelectric detection module 15, a second photoelectric detection module 16 and a signal demodulation module 17; the repeater 30 is composed of a fourth wavelength division multiplexer 20, a second pump 21, a second circulator 22, a fifth coupler 23, a second optical amplifier 24, a third circulator 25, a fifth wavelength division multiplexer 26, a third pump 27, a sixth coupler 28, and a third optical amplifier 29.
The first optical fiber distributed acoustic sensing system 18-1 outputs the amplified pulse excitation light to the front end of the front section of sensing optical fiber 19 of 100km to realize acoustic detection of the front 50km optical fiber, and simultaneously outputs the pulse excitation light to the repeater 30 through the optical fiber for long distance transmission, and the pulse excitation light is amplified by the repeater 30 and then is input to the tail end of the front section of sensing optical fiber 19 to realize acoustic detection of the rear 50km optical fiber; the second optical fiber distributed acoustic sensing system 18-2 outputs the amplified pulse excitation light to the tail end of the rear section sensing optical fiber 31 of 100km for acoustic detection of the rear 50km optical fiber, and simultaneously outputs the pulse excitation light to the repeater 30 through the optical fiber for long distance transmission, and the amplified pulse excitation light is input to the head end of the rear section sensing optical fiber 31 for acoustic detection of the front 50km optical fiber.
The first light source 1 and the second light source 2 output continuous light, and two narrow linewidth lasers with different wavelengths are adopted, and the central wavelength is around 1550 nm.
The first wavelength division multiplexer 5 is used for combining light of two wavelengths into one beam, the second wavelength division multiplexer 9 is used for demultiplexing light of two wavelengths combined into one beam into two wavelengths, and a dense wavelength division multiplexer may be used.
The optical modulator 6 is used to modulate the continuous light into pulse light, and an acousto-optic modulator or an electro-optic modulator can be used to modulate the pulse width of the light pulse.
An arbitrary waveform generator 7 is used to drive the optical modulator 6 to generate pulsed light, either a high sample rate signal generator or an acousto-optic modulator driver may be employed.
The first optical amplifier 8, the optical second amplifier 24, and the third optical amplifier 29 are used to amplify the optical power of the pulsed light, and an erbium-doped fiber amplifier, or a praseodymium-doped fiber amplifier may be used.
The first pump 11, the second pump 21 and the third pump 27 are used for providing a pump light source for distributed amplification of the probe pulse light, and raman pumping can be used.
The third wavelength division multiplexer 12, the fourth wavelength division multiplexer 20 and the fifth wavelength division multiplexer 26 are used for coupling the pump light and the detection pulse light into the sensing optical fiber, and wavelength division multiplexers of commercial corresponding wave bands can be adopted.
The first photoelectric detection module 15 and the second photoelectric detection module 16 are used for converting interference optical signals into electric signals, and direct current interference in the interference signals is eliminated by adopting an optical balance detector.
The signal demodulation module 17 is used for performing data processing and demodulation on the electric signals, restoring information such as the position and the phase of an external sound field, and realizing distributed sound wave real-time monitoring.
Working principle: the continuous light output by the first light source 1 and the second light source 2 of the FODAS system is divided into two beams by the first coupler 3 and the second coupler 4 respectively, the continuous light output by the first output port of the first coupler 3 and the first output port of the second coupler 4 is combined into one beam by the first wavelength division multiplexer 5, then modulated into pulse light by the optical modulator 6, the pulse light is amplified by the first optical amplifier 8 and then output the required high-power detection pulse light, and then the pulse light is demultiplexed into two wavelengths (wavelength one and wavelength two) by the second wavelength division multiplexer 9.
The detection pulse light with the wavelength II obtained in the first optical fiber distributed acoustic sensing system 18-1 enters the third wavelength division multiplexer 12 through the first circulator 10, meanwhile, pump light generated by the first pump 11 enters the third wavelength division multiplexer 12, the pump light and the detection pulse light enter the front section sensing optical fiber 19 of 100km through the third wavelength division multiplexer 12 to realize the detection of the front 50km optical fiber, when the pump light power reaches a nonlinear effect threshold value, the pump light energy is transferred to the detection pulse light, the backward Rayleigh scattered light with the power increased is obtained in the front section sensing optical fiber 19, the pumping distributed amplification is completed, the backward Rayleigh scattered light output through the first circulator 10 and the local continuous light output through the second coupler 4 are interfered in the third coupler 13 to generate interference signals, and then the interference signals are converted into electric signals through the first photoelectric detection module 15; the obtained detection pulse light with the wavelength I is remotely transmitted to the second circulator 22 in the repeater 30 through the transmission optical fiber, the pump light generated by the second pump 21 and the detection pulse light output by the second circulator 22 enter the front section sensing optical fiber 19 of 100km through the fourth wavelength division multiplexer 20 to realize the detection of the rear 50km optical fiber, the backward Rayleigh scattered light output by the second circulator 22 and the local continuous light output by the first coupler 3 remotely transmitted to the inside of the repeater 30 through the optical fiber are interfered by the fifth coupler 23 to generate interference signals, and the interference pulse light output by the fifth coupler 23 is amplified by the second optical amplifier 24 and then remotely transmitted back to the fourth coupler 14 in the first optical fiber distributed acoustic sensing system 18-1 through the front section sensing optical fiber, and then is converted into electric signals through the second photoelectric detection module 16.
The signal demodulation module 17 processes and demodulates the electric signals obtained by the first photoelectric detection module 15 and the second photoelectric detection module 16, restores information such as the position and the phase of an external sound field, and realizes distributed acoustic wave sensing of the front-stage sensing optical fiber 19. The detection process of the second optical fiber distributed acoustic sensing system 18-2 is similar to that of the first optical fiber distributed acoustic sensing system 18-1, except that in the second optical fiber distributed acoustic sensing system 18-2, detection pulse light enters a rear section sensing optical fiber 31 of 100km through a third wavelength division multiplexer 12 to realize detection of a rear section sensing optical fiber of 50km, the obtained detection pulse light with a first wavelength is remotely transmitted to a third circulator 25 in a repeater 30 through a transmission optical fiber, pump light generated by a third pump 27 and detection pulse light output through the third circulator 25 enter the rear section sensing optical fiber 31 of 100km through a fifth wavelength division multiplexer 26 to realize detection of a front section sensing optical fiber of 50km, backward Rayleigh scattered light output through the third circulator 25 and local continuous light output through the first coupler 3 in the repeater 30 are subjected to interference generation interference signals through a sixth coupler 28, the interference pulse light output by the sixth coupler 28 is remotely transmitted back to the third circulator 25 through the optical fiber to the third circulator 25 after being amplified, the pump light generated by the third pump light and the detection pulse light enters the rear section sensing optical fiber 25 to realize detection of 100km through the rear section sensing optical fiber 31 of the rear section sensing optical fiber, the detection pulse light is converted into electric signals by the second optical fiber distributed acoustic sensor system 16, and the second optical fiber module 16 is subjected to the phase-conversion of the acoustic sensor module 16, and the external information is restored to realize the detection of the acoustic module 16. Two sections of 100km sensing optical fibers are connected through a repeater 30, and finally the distributed optical fiber acoustic sensing system realizes a sensing distance of 200km long distance.
According to the invention, the repeater is added between the sensing optical fibers, the sensing optical fibers are divided into two sections to be detected respectively through the two FODAS systems, so that the detection distance of the detection pulse light in a single FODAS system is reduced; the two ends of each section of sensing optical fiber are simultaneously detected in a segmented mode by utilizing two detection pulse lights with different wavelengths, and the distributed Raman amplification is adopted to provide enough gain for the detection pulse lights so as to overcome the optical fiber loss, improve the detection pulse light power at the lower part of the detection pulse light power and effectively extend the sensing distance of the system; and a coherent heterodyne detection mode is adopted, so that the signal to noise ratio of the system is increased, and the sensitivity is improved.

Claims (9)

1. A long-distance optical fiber distributed acoustic wave sensing device based on a repeater is characterized in that: the device consists of a first optical fiber distributed acoustic sensing system (18-1), a second optical fiber distributed acoustic sensing system (18-2), a front section of sensing optical fiber (19), a rear section of sensing optical fiber (31) and a repeater (30); wherein,
the repeater (30) is embedded in the joint of the front section sensing optical fiber (19) and the rear section sensing optical fiber (31) and is respectively connected with the front section sensing optical fiber (19) and the rear section sensing optical fiber (31) and is used for amplifying light pulses transmitted by the first optical fiber distributed acoustic sensing system (18-1) and the second optical fiber distributed acoustic sensing system (18-2) in a long distance and amplifying and outputting generated interference light signals;
the first optical fiber distributed acoustic sensing system (18-1) is connected with the head end of the front section of sensing optical fiber (19), and the tail end of the rear section of sensing optical fiber (31) is connected with the second optical fiber distributed acoustic sensing system (18-2); the first optical fiber distributed acoustic sensing system (18-1) outputs amplified pulse excitation light to be input into a front section sensing optical fiber (19) to realize front half detection of the front section sensing optical fiber, and simultaneously outputs the pulse excitation light to be remotely transmitted to a repeater (30) through the front section sensing optical fiber (19), amplified by the repeater (30) and then input into the tail end of the front section sensing optical fiber (19) to realize rear half detection of the front section sensing optical fiber;
the second optical fiber distributed acoustic sensing system (18-2) outputs the amplified pulse excitation light to the tail end of the rear-section sensing optical fiber (31) to realize the detection of the rear half part of the rear-section sensing optical fiber, and simultaneously outputs the pulse excitation light to be remotely transmitted to the repeater (30) through the rear-section sensing optical fiber (31), amplified by the repeater (30) and then input to the head end of the rear-section sensing optical fiber (31) to realize the detection of the front half part of the rear-section sensing optical fiber.
2. The repeater-based long-distance fiber optic distributed acoustic wave sensing device of claim 1, wherein: the first optical fiber distributed acoustic sensing system (18-1) and the second optical fiber distributed acoustic sensing system (18-2) comprise a first light source (1), a second light source (2), a first coupler (3), a second coupler (4), a first wavelength division multiplexer (5), an optical modulator (6), an arbitrary waveform generator (7), a first optical amplifier (8), a second wavelength division multiplexer (9), a first circulator (10), a first pump (11), a third wavelength division multiplexer (12), a third coupler (13), a fourth coupler (14), a first photoelectric detection module (15), a second photoelectric detection module (16) and a signal demodulation module (17) which are sequentially arranged on an optical path; wherein,
the output end of the first light source (1) is connected with the input end of the first coupler (3), the output end of the second light source (2) is connected with the input end of the second coupler (4), one of the output ends of the first coupler (3) and the second coupler (4) is respectively connected with two input ends of the first wavelength division multiplexer (5), the output end of the first wavelength division multiplexer (5) is connected with the input end of the optical modulator (6), the output end of the arbitrary waveform generator (7) is connected with the modulation input end of the optical modulator (6), the output end of the optical modulator (6) is connected with the input end of the first optical amplifier (8), the output end of the first optical amplifier (8) is connected with the input end of the second wavelength division multiplexer (9), one output end of the second wavelength division multiplexer (9) is connected with the input end of the first circulator (10), one output end of the first circulator (10) is connected with one input end of the third wavelength division multiplexer (12), the output end of the first circulator (10) is connected with the other output end of the third wavelength division multiplexer (13), the other output end of the second circulator (13) is connected with the other input end of the third wavelength division multiplexer (12), the other output end of the third wavelength division multiplexer (13) is connected with the other input end of the third wavelength division multiplexer (13), two output ends of the third coupler (13) are connected with the first photoelectric detection module (15), two output ends of the fourth coupler (14) are connected with the second photoelectric detection module (16), and output ends of the first photoelectric detection module (15) and the second photoelectric detection module (16) are connected with input ends of the signal demodulation module (17).
3. The repeater-based long-distance fiber optic distributed acoustic wave sensing device of claim 2, wherein: the repeater (30) consists of a second pump (21), a fourth wavelength division multiplexer (20), a second circulator (22), a fifth coupler (23), a second optical amplifier (24), a third circulator (25), a fifth wavelength division multiplexer (26), a third pump (27), a sixth coupler (28) and a third optical amplifier (29) which are sequentially arranged, a front-section sensing optical fiber (19) connected from the third wavelength division multiplexer (12) in the first optical fiber distributed acoustic sensing system (18-1) is connected with the output end of the fourth wavelength division multiplexer (20), the output end of the second pump (21) is connected with one input end of the fourth wavelength division multiplexer (20), one output end of the second circulator (22) is connected with the other input end of the fourth wavelength division multiplexer (20), the other output end of the second circulator (22) is connected with one input end of the fifth coupler (23), and the output end of the fifth coupler (23) is connected with the input end of the second optical amplifier (24); the rear section sensing optical fiber (31) connected from the third wavelength division multiplexer (12) in the second optical fiber distributed acoustic sensing system (18-2) is connected with the output end of the fifth wavelength division multiplexer (26), the output end of the third pump (27) is connected with one input end of the fifth wavelength division multiplexer (26), one output end of the third circulator (25) is connected with the other input end of the fifth wavelength division multiplexer (26), the other output end of the third circulator (25) is connected with one input end of the sixth coupler (28), and the output end of the sixth coupler (28) is connected with the input end of the third optical amplifier (29).
4. The repeater-based long-distance fiber optic distributed acoustic wave sensing device of claim 3, wherein: an output end of a second wavelength division multiplexer (9) of the first optical fiber distributed acoustic sensing system (18-1) is remotely transmitted to an input end of a second circulator (22) through a front-section sensing optical fiber (19); the other output end of the first coupler (3) of the first optical fiber distributed acoustic sensing system (18-1) is remotely transmitted to the other input end of the fifth coupler (23) of the repeater (30) through the front-section sensing optical fiber (19); one output end of a second wavelength division multiplexer (9) of the second optical fiber distributed acoustic sensing system (18-2) is remotely transmitted to an input end of a third circulator (25) of the repeater (30) through a rear-section sensing optical fiber (31), and the other output end of a first coupler (3) of the second optical fiber distributed acoustic sensing system (18-2) is remotely transmitted to the other input end of a sixth coupler (28) of the repeater (30) through the rear-section sensing optical fiber (31).
5. The repeater based long distance fiber optic distributed acoustic wave sensing device of claim 4, wherein: the output end of the second optical amplifier (24) of the repeater (30) is remotely transmitted to the input end of the fourth coupler (14) of the first optical fiber distributed acoustic sensing system (18-1) through the front-end sensing optical fiber (19); the output end of the third optical amplifier (29) of the repeater (30) is remotely transmitted to the input end of the fourth coupler (14) of the second optical fiber distributed acoustic sensing system (18-2) through the rear sensing optical fiber (31).
6. The repeater-based long-distance fiber optic distributed acoustic wave sensing device of claim 2, wherein: the first optical source (1) and the second optical source (2) in the first optical fiber distributed acoustic sensing system (18-1) and the second optical fiber distributed acoustic sensing system (18-2) are two optical sources with different center wavelengths.
7. The repeater-based long-distance fiber optic distributed acoustic wave sensing device of claim 2, wherein: the first wavelength division multiplexer (5) and the second wavelength division multiplexer (9) in the first optical fiber distributed acoustic sensing system (18-1) and the second optical fiber distributed acoustic sensing system (18-2) are respectively used for combining and de-combining light waves with two wavelengths.
8. The repeater-based long-distance fiber optic distributed acoustic wave sensing device of claim 2, wherein: an arbitrary waveform generator (7) in the first optical fiber distributed acoustic sensing system (18-1) and the second optical fiber distributed acoustic sensing system (18-2) is used for generating a pulse modulation signal to drive the optical modulator.
9. The repeater-based long-distance fiber optic distributed acoustic wave sensing device of claim 2, wherein: the first photoelectric detection module (15) and the second photoelectric detection module (16) in the first optical fiber distributed acoustic sensing system (18-1) and the second optical fiber distributed acoustic sensing system (18-2) are light balance detection modules.
CN202311330495.XA 2023-10-13 2023-10-13 Long-distance optical fiber distributed acoustic wave sensing device based on repeater Pending CN117346879A (en)

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