CN110631617B - Long-distance high-resolution Brillouin optical time domain analysis method - Google Patents

Long-distance high-resolution Brillouin optical time domain analysis method Download PDF

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CN110631617B
CN110631617B CN201910900099.3A CN201910900099A CN110631617B CN 110631617 B CN110631617 B CN 110631617B CN 201910900099 A CN201910900099 A CN 201910900099A CN 110631617 B CN110631617 B CN 110631617B
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light
optical fiber
optical
pulse
module
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CN110631617A (en
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陈科新
吴正明
张树龙
姜明武
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Suzhou Guangge Technology Co Ltd
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Suzhou Guangge Technology Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35338—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using other arrangements than interferometer arrangements
    • G01D5/35354—Sensor working in reflection
    • G01D5/35358—Sensor working in reflection using backscattering to detect the measured quantity
    • G01D5/35364—Sensor working in reflection using backscattering to detect the measured quantity using inelastic backscattering to detect the measured quantity, e.g. using Brillouin or Raman backscattering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
    • G01D5/35383—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using multiple sensor devices using multiplexing techniques
    • G01D5/35387—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using multiple sensor devices using multiplexing techniques using wavelength division multiplexing

Abstract

The invention discloses a long-distance high-resolution Brillouin optical time domain analysis method, which comprises the following steps of: generating pulsed light I, pulsed light II, sweep-frequency continuous light I and sweep-frequency continuous light II; the first pulse light is emitted from the head end of the first optical fiber to be detected, and the second pulse light is emitted from the tail end of the second optical fiber to be detected; the continuous light I is emitted from the head end of the transmission optical fiber I and is emitted from the tail end of the transmission optical fiber I and then is emitted into the tail end of the optical fiber I to be detected, and the continuous light II is emitted from the tail end of the transmission optical fiber II and is emitted from the head end of the transmission optical fiber II and then is emitted into the head end of the optical fiber II to be detected; forming a first detection light in the first optical fiber to be detected and forming a second detection light in the second optical fiber to be detected; collecting the light intensity of the first detection light and converting the light intensity into a first digital signal, and collecting the light intensity of the second detection light and converting the light intensity into a second digital signal; calculating to obtain a first measurement data and a second measurement data; splicing the first measurement data and the second measurement data to obtain final measurement data; the invention has long measuring distance, good precision and high spatial resolution.

Description

Long-distance high-resolution Brillouin optical time domain analysis method
Technical Field
The invention relates to the technical field of optical measurement, in particular to a long-distance high-resolution Brillouin optical time domain analyzer.
Background
Compared with Brillouin Optical Time Domain Reflectometer (BOTDR) and other distributed optical fiber sensing systems, the Brillouin Optical Time Domain Analyzer (BOTDA) has the advantages of high measuring speed, long measuring distance, high spatial resolution and high measuring precision; as shown in fig. 1, in the conventional BOTDA, the optical fiber adopts a loop structure configured in a U-shaped round-trip configuration; pulse pump light and continuous probe light are injected from two ends of the optical fiber, the frequency of the pulse pump light is fixed and unchanged, and the frequency of the continuous probe light is scanned back and forth, so that the optical fiber Brillouin spectrum is scanned, and the optical fiber temperature and strain sensing is realized.
However, the accuracy of the BOTDA in the whole measurement range is deteriorated with the increase of the optical fiber distance due to the gradual attenuation of the pulsed pump light caused by the increase of the measurement distance, the non-local effect caused by the limited extinction ratio of the pulsed pump light, the insufficient transmission distance caused by the limitation of the stimulated brillouin threshold of the continuous probe light, and the like, the measurement accuracy of the head end of the optical fiber (near the input end of the pulsed pump light) is high, and the measurement accuracy of the tail end of the optical fiber (near the input end of the continuous probe light) is poor, which is particularly obvious in long-distance measurement, so that the high spatial resolution is difficult to achieve in the long-distance measurement under the requirement of ensuring the measurement accuracy.
At present, in the temperature or stress measurement application in the fields of oil and gas pipelines, overhead lines OPGW, seabed photoelectric composite cables, seabed optical cables and the like, the requirements on long distance, high spatial resolution and high measurement precision are more and more; for example, the transmission distance from an onshore switch station to an offshore booster station of an existing wind farm in Jiangsu even exceeds 100km (namely, the loop exceeds 200 km), and as the offshore wind farm is developed from offshore to open sea, a shallow sea is developed to a deep sea, so that the requirement of remote measurement is more and more urgent; then, the measuring distance of domestic and foreign commercialized systems can only be 60km (namely 120km loop), and the precision can be guaranteed to be +/-1 ℃ when the spatial resolution is 3.5 m; the existing effective improvement schemes include heterodyne detection, host near-end pumping amplification and far-end remote pumping amplification, the former scheme is complex and has high implementation difficulty, and the latter scheme cannot solve the contradiction between long distance and high spatial resolution and high measurement precision, so a method capable of solving the problems needs to be found.
Disclosure of Invention
In view of the above, there is a need to overcome at least one of the above-mentioned drawbacks in the prior art, and the present invention provides a long-distance high-resolution brillouin optical time domain analysis method, comprising the steps of: generating pulsed light I, pulsed light II, sweep-frequency continuous light I and sweep-frequency continuous light II; the first pulse light is emitted from the head end of the first optical fiber to be detected of the photoelectric composite cable, and the second pulse light is emitted from the tail end of the second optical fiber to be detected of the photoelectric composite cable; the sweep frequency continuous light I is emitted from the head end of the transmission optical fiber I, emitted from the tail end of the transmission optical fiber I and then emitted into the tail end of the optical fiber I to be detected through optical amplification, and the sweep frequency continuous light II is emitted from the tail end of the transmission optical fiber II, emitted from the head end of the transmission optical fiber II and then emitted into the head end of the optical fiber II to be detected through optical amplification; the pulsed light I and the swept frequency continuous light I interact in the optical fiber I to be detected to form a probe light I, and the pulsed light II and the swept frequency continuous light II interact in the optical fiber II to be detected to form a probe light II; collecting the light intensity of the first detection light and converting the light intensity into a first digital signal, and collecting the light intensity of the second detection light and converting the light intensity into a second digital signal; calculating to obtain first measurement data from the head end to the tail end of the first optical fiber to be measured according to the first digital signal, and calculating to obtain second measurement data from the tail end to the head end of the second optical fiber to be measured according to the second digital signal; and splicing the first measurement data and the second measurement data according to the precision of the first measurement data and the second measurement data to obtain final measurement data.
According to the background technology of the patent and the prior art, the current scheme for improving the long-distance measurement precision of the BOTDA comprises heterodyne detection, near-end pumping amplification and far-end remote pumping amplification of a host, wherein the scheme of the former is complex and has high realization difficulty, and the latter can not solve the contradiction between long distance and high spatial resolution and high measurement precision; the invention discloses a long-distance high-resolution Brillouin optical time domain analysis method, which comprises the steps of injecting a beam of pulse light into a to-be-measured optical fiber in a photoelectric composite cable from the head end of the photoelectric composite cable, and injecting a beam of continuous light from the tail end of the photoelectric composite cable to the to-be-measured optical fiber in the photoelectric composite cable after the continuous light is amplified at a position close to the tail end of the photoelectric composite cable, so that measurement data of the to-be-measured optical fiber from the head end to the tail end of the photoelectric composite cable is measured and used as measurement data I; simultaneously, injecting a beam of pulse light into the optical fiber II to be measured in the photoelectric composite cable from the tail end of the photoelectric composite cable, and injecting a beam of continuous light from the head end of the photoelectric composite cable to the optical fiber II to be measured in the photoelectric composite cable after the continuous light is amplified at a position close to the head end of the photoelectric composite cable, so that the measured data of the optical fiber II to be measured from the tail end to the head end of the photoelectric composite cable is measured and used as second measured data; the measurement system and the measurement system have the same measurement time and measurement simultaneously, and the measurement system is spliced with the measurement data I and the measurement data II through the data inversion system to obtain final measurement data with high precision, so that long-distance measurement is realized, the measurable distance is at least 100km, the spatial resolution is high, and the measurement precision is good.
The first transmission optical fiber and the second transmission optical fiber can be any two single-core single-mode optical fibers in the same photoelectric composite cable, and can also be any one single-core single-mode optical fiber in different photoelectric composite cables, and the first transmission optical fiber, the second transmission optical fiber and the first optical fiber to be tested can be located in the same photoelectric composite cable or not.
The main control system is used for fitting each position point of the first optical fiber to be measured by using a frequency point-intensity discrete point group value to obtain a central frequency value of each point, and the temperature or strain value can be calculated through the change of the central frequency value to be used as the first measurement data; and the second main control system uses the frequency point-intensity discrete point group value to fit at each position point of the second optical fiber to be measured to obtain the central frequency value of each point, and the temperature or strain value can be calculated through the change of the central frequency value to be used as the second measurement data.
In addition, the long-distance high-resolution Brillouin optical time domain analysis method disclosed by the invention also has the following additional technical characteristics:
further, the swept-frequency continuous light is subjected to optical amplification and then is subjected to filtering processing to be emitted to the tail end of the first optical fiber to be detected; and the swept frequency continuous light II is subjected to optical amplification and then is subjected to filtering treatment and then is emitted into the head end of the optical fiber II to be detected.
Further, the swept-frequency continuous light is optically amplified and then is emitted into the tail end of the first optical fiber to be detected through a one-way channel; and the swept frequency continuous light II is optically amplified and then is emitted into the head end of the optical fiber II to be detected through a one-way channel.
The unidirectional channel is an isolation module, such as a fiber optic isolator.
Further, the head end of the photoelectric composite cable is used as a starting point to intercept data of 30-70% of the first measured data as first intercepted data, the tail end of the photoelectric composite cable is used as a starting point to intercept the rest of data in front of the second measured data as second intercepted data, and the head end of the photoelectric composite cable is used as a starting point to splice the first intercepted data and the second intercepted data to obtain the final measured data.
Under the same working condition, the interception ratios of the first measurement data and the second measurement data are both 50%.
Further, the generation of the pulsed light i, the pulsed light ii, the swept continuous light i and the swept continuous light ii includes the following steps: dividing a laser beam into two beams, and dividing the laser beam into two beams; one beam of the first laser beam is subjected to pulse modulation to form a first pulse light, and one beam of the second laser beam is subjected to pulse modulation to form a second pulse light; and the other beam of the first laser forms the first swept-frequency continuous light through frequency sweeping, and the other beam of the second laser forms the second swept-frequency continuous light through pulse modulation.
Further, the generation of the pulsed light i, the pulsed light ii, the swept continuous light i and the swept continuous light ii includes the following steps: pulse-modulating the pulse laser to form the pulse light I; one beam of the pulse laser II is subjected to pulse modulation to form pulse light II; frequency locking between the first continuous light laser and the first pulse laser is performed to form the first swept continuous light; and the second continuous light laser passes through the frequency lock between the second pulse laser and the second continuous light laser to form the second swept continuous light.
The first pulse laser is used for forming the first pulse light; the second pulse laser is used for forming a second pulse light; the continuous laser I is used for forming sweep-frequency continuous light I; the continuous laser II is used for forming the sweep continuous light II.
Furthermore, the number of the photoelectric composite cables is N, each photoelectric composite cable is provided with a first optical fiber to be detected and a second optical fiber to be detected, before the first pulse light, the second pulse light, the first sweep frequency continuous light and the second sweep frequency continuous light are generated, a plurality of 1 × N optical switches are switched, so that the first optical fiber to be detected and the first sweep frequency continuous light, which are incident into the first pulse light, are the same optical fiber, the second optical fiber to be detected and the second optical fiber to be detected, which are incident into the second pulse light, are the same optical fiber, and the first optical fiber to be detected and the second optical fiber to be detected, which are incident into the first pulse light, are two optical fibers in the same photoelectric composite cable respectively.
According to another aspect of the present invention, there is provided a long-distance high-resolution brillouin optical time domain analyzer based on the above-mentioned long-distance high-resolution brillouin optical time domain analysis method, including: the measurement system is provided with a first pulse continuous light generation module, a first signal processing and collecting module, a first communication module, a first main control module and a first optical amplification module; the first pulse continuous optical module is provided with a first pulse output end and a first continuous optical output end; the pulse output end I is connected with a first port of the optical fiber circulator I, a second port of the optical fiber circulator I is used for being directly or indirectly connected with a head end of a first optical fiber to be detected of the photoelectric composite cable, the continuous light output end I is used for being directly or indirectly connected with a head end of a first transmission optical fiber, and an input end and an output end of the optical amplification module I are respectively used for being directly or indirectly connected with a tail end of the first transmission optical fiber and a tail end of the first optical fiber to be detected; the third port of the first optical fiber circulator is connected with the input end of the first signal processing and collecting module, and the first main control module is in communication connection with the first signal processing and collecting module and the first communication module; the second measurement system is provided with a second pulse continuous light generation module, a second signal processing and collecting module, a second communication module, a second main control module and a second optical amplification module; the second pulse continuous light module is provided with a second pulse output end and a second continuous light output end; the second pulse output end is connected with a first port of a second optical fiber circulator, a second port of the second optical fiber circulator is used for being directly or indirectly connected with the tail end of a second optical fiber to be detected of the photoelectric composite cable, the second continuous light output end is used for being directly or indirectly connected with the tail end of a second transmission optical fiber, and the input end and the output end of the second optical amplification module are respectively used for being directly or indirectly connected with the head end of the second transmission optical fiber and the head end of the second optical fiber to be detected; a third port of the second optical fiber circulator is connected with an input end of the second signal processing and collecting module, and the second main control module is in communication connection with the second signal processing and collecting module and the communication module; and the data inversion system is respectively in communication connection with the first communication module and the second communication module.
In addition, the long-distance high-resolution Brillouin optical time domain analysis method disclosed by the invention also has the following additional technical characteristics:
further, the first optical amplification module is an erbium-doped fiber amplifier (EDFA) or a Raman Fiber Amplifier (RFA); and the second optical amplification module is an erbium-doped fiber amplifier (EDFA) or a Raman Fiber Amplifier (RFA).
Furthermore, the measurement system also comprises a first isolation module, the input end of the first isolation module is directly or indirectly connected with the output end of the first optical amplification module, and the output end of the first isolation module is used for being directly or indirectly connected with the tail end of the first optical fiber to be measured; the second measurement system further comprises a second isolation module, the input end of the second isolation module is directly or indirectly connected with the output end of the second optical amplification module, and the output end of the second isolation module is used for being directly or indirectly connected with the head end of the second optical fiber to be measured.
Further, the first isolator and the second isolator adopt optical fiber Isolators (ISO).
After the pulse light passes through the optical fiber to be detected, the pulse light is reversely cut off by the ISO, so that the direct current background of the pulse light with the limited extinction ratio cannot be transmitted into the transmission optical fiber through the ISO to act with the continuous light, the continuous light enters the optical fiber to be detected through the ISO in the forward direction and then is subjected to energy interaction with the pulse light, the generation of a non-local effect is effectively reduced, in addition, due to the existence of the ISO, the pulse light is cut off, the acquisition time of the signal processing acquisition module is reduced to half of the original acquisition time, and the measurement time is effectively shortened.
Furthermore, the measurement system also comprises a first filtering module, the input end of the first filtering module is directly or indirectly connected with the output end of the first optical amplification module, and the output end of the first filtering module is used for being directly or indirectly connected with the tail end of the first optical fiber to be measured; the second measurement system further comprises a second filtering module, the input end of the second filtering module is directly or indirectly connected with the output end of the second optical amplification module, and the output end of the second filtering module is used for being directly or indirectly connected with the head end of the second optical fiber to be measured.
The first filtering module adopts a Wavelength Division Multiplexer (WDM) or a Fiber Bragg Grating (FBG) module; and the second filtering module adopts a Wavelength Division Multiplexer (WDM) or a Fiber Bragg Grating (FBG) module.
The central wavelength of the filtering module is continuous optical wavelength, and when the optical amplification module adopts an EDFA, spontaneous emission ASE noise of the EDFA can be filtered; when the optical amplification module adopts the RFA, the Raman pump light of the RFA can be filtered, and the influence of noise is reduced.
The system further comprises a first host and a second host, wherein the first host comprises the first pulse continuous optical module, the first signal processing and collecting module, the first communication module, the first main control module and the second optical amplifying module; the host computer II comprises the pulse continuous optical module II, the signal processing and collecting module II, the communication module II, the main control module II and the optical amplifying module I.
Furthermore, the first host further comprises a second isolator and a second filtering module; the second host further comprises the first isolator and the first filtering module.
Further, the measuring system also comprises a first laser and a first coupler; the first pulse continuous optical module is provided with a first pulse optical module and a first continuous optical module; the output end of the first laser is connected with the input end of the first coupler, and the two output ends of the first coupler are respectively connected with the first pulse light module and the first continuous light module; the second measurement system further comprises a second laser and a second coupler; the second pulse continuous optical module is provided with a second pulse optical module and a second continuous optical module; and the output end of the second laser is connected with the input end of the second coupler, and the two output ends of the second coupler are respectively connected with the second pulse light module and the second continuous light module.
Furthermore, the first host further comprises the first laser and the first coupler; the second host further comprises a second laser and a second coupler.
Further, the continuous optical module I is provided with a microwave source I and an electro-optical modulator I; the optical input end of the first electro-optical modulator is connected with one output end of the first coupler, and the electrical signal input end of the first electro-optical modulator is connected with the microwave source; the output end of the first electro-optical modulator is used for being directly or indirectly connected with the head end of the first transmission optical fiber; the continuous optical module II is provided with a microwave source II and an electro-optical modulator II; the optical input end of the second electro-optical modulator is connected with one output end of the second coupler, and the electrical signal input end of the second electro-optical modulator is connected with the microwave source; the output end of the electro-optical modulator II is used for being directly or indirectly connected with the tail end of the transmission optical fiber II; the first pulse light module is provided with a first pulse modulation unit; the pulse light module II is provided with a pulse modulation unit II.
Further, the microwave amplitude of the microwave source is 10-14 GHz.
Furthermore, the first continuous optical module further comprises a first optical amplifier and a first adjustable optical attenuator, the output end of the first electro-optical modulator is connected with the input end of the first optical amplifier, and the output end of the first optical amplifier is used for being directly or indirectly connected with the head end of the first transmission optical fiber; the second continuous optical module is also provided with a second optical amplifier and a second adjustable optical attenuator, the output end of the second electro-optical modulator is connected with the input end of the second optical amplifier, and the output end of the second optical amplifier is used for being directly or indirectly connected with the tail end of the second transmission optical fiber. Furthermore, the measurement system is provided with a frequency locking modulation module I; the pulse continuous optical module I is provided with a pulse optical module I and a continuous optical module I, and the pulse optical module I is provided with a pulse laser I and a pulse modulation unit I; the first continuous optical module is provided with a first continuous optical laser, and the output end of the first continuous optical laser is used for being directly or indirectly connected with the head end of the first transmission optical fiber; the first frequency locking modulation module is respectively connected with the first pulse laser and the first continuous light laser; the second measurement system is provided with a second frequency locking modulation module; the pulse continuous optical module II is provided with a pulse optical module II and a continuous optical module II, and the pulse optical module is provided with a pulse laser II and a pulse modulation unit II; the second continuous optical module is provided with a second continuous light laser, and the output end of the second continuous light laser is used for being directly or indirectly connected with the tail end of the second transmission optical fiber; and the second frequency locking modulation module is respectively connected with the second pulse laser and the second continuous light laser.
Further, the first pulse modulation unit is an electro-optical modulator (EOM), an acousto-optical modulator (AOM) or a Semiconductor Optical Amplifier (SOA).
Furthermore, the first continuous optical module further comprises a first optical amplifier and a first adjustable optical attenuator, the output end of the first continuous optical laser 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 first adjustable optical attenuator, and the output end of the first adjustable optical attenuator is used for being directly or indirectly connected with the head end of the first transmission optical fiber; the continuous optical module II is also provided with a second optical amplifier and a second adjustable optical attenuator, the output end of the second laser for continuous light is connected with the input end of the second optical amplifier, the output end of the second optical amplifier is connected with the input end of the second adjustable optical attenuator, and the output end of the second adjustable optical attenuator is used for being directly or indirectly connected with the tail end of the second transmission optical fiber.
Furthermore, the first pulse light module further comprises a first optical amplifier, a first adjustable optical attenuator and a first polarization scrambler, and the second pulse light module further comprises a second optical amplifier, a second adjustable optical attenuator and a second polarization scrambler.
Further, the first frequency locking modulation module and the second frequency locking modulation module are optical phase locking modules (OPLLs).
Performing frequency locking at about 12GHz between the pulsed laser and the continuous light laser by using an optical phase locking module (OPLL); the laser emitted by the pulse laser is modulated by EOM/AOM/SOA to form pulse light.
Furthermore, the measuring system also comprises a pulse 1 xN optical switch I and a continuous 1 xN optical switch I; the input end of the first pulse 1 xN optical switch is connected with the second port of the first optical fiber circulator, and the N output ends of the first pulse 1 xN optical switch are respectively used for being connected with the head ends of the first optical fibers to be tested of the N photoelectric composite cables; the input end of the first continuous 1 xN optical switch is connected with the output end of the first optical amplification module, and the N output ends of the first continuous 1 xN optical switch are respectively used for being connected with the tail ends of the N optical fibers to be detected; the second measurement system further comprises a second pulse 1 xN optical switch and a second continuous 1 xN optical switch; the input end of the pulse 1 xN optical switch II is connected with the second port of the optical fiber circulator II, and N output ends of the pulse 1 xN optical switch II are respectively used for being connected with the tail ends of the optical fibers II to be tested of the N photoelectric composite cables; the input end of the continuous 1 xN optical switch II is connected with the output end of the optical amplification module II, and N output ends of the continuous 1 xN optical switch II are respectively used for being connected with the head ends of N optical fibers II to be detected; the first main control module is in communication connection with the first pulse 1 xN optical switch and the second continuous 1 xN optical switch; and the second main control module is in communication connection with the second pulse 1 xN optical switch and the first continuous 1 xN optical switch.
Furthermore, the first host further comprises a first pulse 1 × N optical switch and a second continuous 1 × N optical switch; the second host further comprises a second pulse 1 xN optical switch and a first continuous 1 xN optical switch.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a block diagram of a prior art Brillouin optical time domain analyzer;
fig. 2 is a structural block diagram of a long-distance high-resolution brillouin optical time domain analyzer provided in the present invention;
fig. 3 is a schematic view of a first host and a second host provided in the present invention respectively connected to N photoelectric composite cables;
FIG. 4 is a diagram illustrating measurement data one provided by the present invention;
FIG. 5 is a diagram of measurement data II provided by the present invention;
fig. 6 is a schematic diagram of the final measurement data provided by the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout; the embodiments described below with reference to the drawings are illustrative only and should not be construed as limiting the invention.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "lateral", "vertical", and the like, indicate orientations and positional relationships based on the orientations and positional relationships shown in the drawings, are used only for convenience in describing the present invention and for simplification of description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
The invention has the following conception that the head end and the tail end of the photoelectric composite cable are respectively provided with a measuring system, the measuring system is used for injecting a beam of pulse light from the head end of the photoelectric composite cable to a to-be-measured optical fiber in the photoelectric composite cable and injecting a beam of continuous light, the continuous light is injected from the tail end of the photoelectric composite cable to the to-be-measured optical fiber in the photoelectric composite cable after being amplified at a position close to the tail end of the photoelectric composite cable, and therefore the measured data of the to-be-measured optical fiber from the head end to the tail end of the photoelectric composite cable is measured and taken as the first measured data; meanwhile, the second measurement system injects a beam of pulse light from the tail end of the photoelectric composite cable to the second optical fiber to be measured in the photoelectric composite cable and injects a beam of continuous light, the continuous light is amplified at a position close to the head end of the photoelectric composite cable and then is injected from the head end of the photoelectric composite cable to the second optical fiber to be measured in the photoelectric composite cable, and therefore measurement data of the second optical fiber to be measured from the tail end to the head end of the photoelectric composite cable are measured and serve as second measurement data; and splicing the first measurement data and the second measurement data through a data inversion system to obtain final measurement data with high precision, thereby realizing long-distance measurement, wherein the measurable distance is at least 100km, and the spatial resolution is high and the measurement precision is good.
FIG. 1 is a block diagram of a prior art Brillouin optical time domain analyzer; fig. 2 is a structural block diagram of a long-distance high-resolution brillouin optical time domain analyzer provided in the present invention; fig. 3 is a schematic view of a first host and a second host provided in the present invention respectively connected to N photoelectric composite cables; FIG. 4 is a diagram illustrating measurement data one provided by the present invention; FIG. 5 is a diagram of measurement data II provided by the present invention; fig. 6 is a schematic diagram of the final measurement data provided by the present invention.
As shown in fig. 2, according to an embodiment of the present invention, a long-distance high-resolution brillouin optical time domain analysis method includes the following steps: generating pulsed light I, pulsed light II, sweep-frequency continuous light I and sweep-frequency continuous light II; the first pulse light is emitted from the head end of the first optical fiber to be detected of the photoelectric composite cable, and the second pulse light is emitted from the tail end of the second optical fiber to be detected of the photoelectric composite cable; the sweep frequency continuous light I is emitted from the head end of the transmission optical fiber I, emitted from the tail end of the transmission optical fiber I and then emitted into the tail end of the optical fiber I to be detected through optical amplification, and the sweep frequency continuous light II is emitted from the tail end of the transmission optical fiber II, emitted from the head end of the transmission optical fiber II and then emitted into the head end of the optical fiber II to be detected through optical amplification; the pulsed light I and the swept frequency continuous light I interact in the optical fiber I to be detected to form a probe light I, and the pulsed light II and the swept frequency continuous light II interact in the optical fiber II to be detected to form a probe light II; collecting the light intensity of the first detection light and converting the light intensity into a first digital signal, and collecting the light intensity of the second detection light and converting the light intensity into a second digital signal; calculating to obtain first measurement data from the head end to the tail end of the first optical fiber to be measured according to the first digital signal, and calculating to obtain second measurement data from the tail end to the head end of the second optical fiber to be measured according to the second digital signal; and splicing the first measurement data and the second measurement data according to the precision of the first measurement data and the second measurement data to obtain final measurement data.
According to the background technology of the patent and the prior art, the current scheme for improving the long-distance measurement precision of the BOTDA comprises heterodyne detection, near-end pumping amplification and far-end remote pumping amplification of a host, wherein the scheme of the former is complex and has high realization difficulty, and the latter can not solve the contradiction between long distance and high spatial resolution and high measurement precision; the invention discloses a long-distance high-resolution Brillouin optical time domain analysis method, which comprises the steps of injecting a beam of pulse light into a to-be-measured optical fiber in a photoelectric composite cable from the head end of the photoelectric composite cable, and injecting a beam of continuous light from the tail end of the photoelectric composite cable to the to-be-measured optical fiber in the photoelectric composite cable after the continuous light is amplified at a position close to the tail end of the photoelectric composite cable, so that measurement data of the to-be-measured optical fiber from the head end to the tail end of the photoelectric composite cable is measured and used as measurement data I; simultaneously, injecting a beam of pulse light into the optical fiber II to be measured in the photoelectric composite cable from the tail end of the photoelectric composite cable, and injecting a beam of continuous light from the head end of the photoelectric composite cable to the optical fiber II to be measured in the photoelectric composite cable after the continuous light is amplified at a position close to the head end of the photoelectric composite cable, so that the measured data of the optical fiber II to be measured from the tail end to the head end of the photoelectric composite cable is measured and used as second measured data; the measurement system and the measurement system have the same measurement time and measurement simultaneously, and the measurement system is spliced with the measurement data I and the measurement data II through the data inversion system to obtain final measurement data with high precision, so that long-distance measurement is realized, the measurable distance is at least 100km, the spatial resolution is high, and the measurement precision is good.
The first transmission optical fiber and the second transmission optical fiber can be any two single-core single-mode optical fibers in the same photoelectric composite cable, and can also be any one single-core single-mode optical fiber in different photoelectric composite cables, and the first transmission optical fiber, the second transmission optical fiber and the first optical fiber to be tested can be located in the same photoelectric composite cable or not.
The main control system is used for fitting each position point of the first optical fiber to be measured by using a frequency point-intensity discrete point group value to obtain a central frequency value of each point, and the temperature or strain value can be calculated through the change of the central frequency value to be used as the first measurement data; and the second main control system uses the frequency point-intensity discrete point group value to fit at each position point of the second optical fiber to be measured to obtain the central frequency value of each point, and the temperature or strain value can be calculated through the change of the central frequency value to be used as the second measurement data.
In addition, the long-distance high-resolution Brillouin optical time domain analysis method disclosed by the invention also has the following additional technical characteristics:
according to some embodiments of the present invention, the swept-frequency continuous light is optically amplified and then emitted into the end of the first optical fiber under test through a filtering process; and the swept frequency continuous light II is subjected to optical amplification and then is subjected to filtering treatment and then is emitted into the head end of the optical fiber II to be detected.
According to some embodiments of the present invention, the swept-frequency continuous light is optically amplified and then emitted into the end of the first optical fiber under test through a one-way channel; and the swept frequency continuous light II is optically amplified and then is emitted into the head end of the optical fiber II to be detected through a one-way channel.
The unidirectional channel is an isolation module, such as a fiber optic isolator.
According to some embodiments of the present invention, the head end of the optical-electrical composite cable is used as a starting point to intercept data of the first 30-70% of the measurement data as first intercepted data, the tail end of the optical-electrical composite cable is used as a starting point to intercept the remaining data before the second measurement data as second intercepted data, and the head end of the optical-electrical composite cable is used as a starting point to splice the first intercepted data and the second intercepted data to obtain the final measurement data.
Under the same working condition, the interception ratios of the first measurement data and the second measurement data are both 50%.
According to some embodiments of the invention, the generating of the pulsed light one, the pulsed light two, the swept continuous light one and the swept continuous light two comprises the steps of: dividing a laser beam into two beams, and dividing the laser beam into two beams; one beam of the first laser beam is subjected to pulse modulation to form a first pulse light, and one beam of the second laser beam is subjected to pulse modulation to form a second pulse light; and the other beam of the first laser forms the first swept-frequency continuous light through frequency sweeping, and the other beam of the second laser forms the second swept-frequency continuous light through pulse modulation.
According to some embodiments of the invention, the generating of the pulsed light one, the pulsed light two, the swept continuous light one and the swept continuous light two comprises the steps of: pulse-modulating the pulse laser to form the pulse light I; one beam of the pulse laser II is subjected to pulse modulation to form pulse light II; frequency locking between the first continuous light laser and the first pulse laser is performed to form the first swept continuous light; and the second continuous light laser passes through the frequency lock between the second pulse laser and the second continuous light laser to form the second swept continuous light.
The first pulse laser is used for forming the first pulse light; the second pulse laser is used for forming a second pulse light; the continuous laser I is used for forming sweep-frequency continuous light I; the continuous laser II is used for forming the sweep continuous light II.
According to some embodiments of the present invention, before the pulsed light i, the pulsed light ii, the swept-frequency continuous light i and the swept-frequency continuous light ii are generated, parameters of each optical module are set, and working parameters of a module for collecting light intensity, including a sampling interval, a sampling point number and the like, are set.
According to some embodiments of the present invention, the number of the photoelectric composite cables is N, each of the photoelectric composite cables has a first optical fiber to be measured and a second optical fiber to be measured, before the first pulse light, the second pulse light, the first swept-frequency continuous light and the second swept-frequency continuous light are generated, a plurality of 1 × N optical switches are switched so that the first optical fiber to be measured which is incident into the first pulse light and the first optical fiber to be measured which is incident into the first swept-frequency continuous light are the same optical fiber, the second optical fiber to be measured which is incident into the second pulse light and the second optical fiber to be measured which is incident into the second swept-frequency continuous light are the same optical fiber, and the first optical fiber to be measured which is incident into the first pulse light and the second optical fiber to be measured which is incident into the second pulse light are two optical fibers in the same photoelectric composite.
According to another aspect of the present invention, there is provided a long-distance high-resolution brillouin optical time domain analyzer based on the above-mentioned long-distance high-resolution brillouin optical time domain analysis method, including: the measurement system is provided with a first pulse continuous light generation module, a first signal processing and collecting module, a first communication module, a first main control module and a first optical amplification module; the first pulse continuous optical module is provided with a first pulse output end and a first continuous optical output end; the pulse output end I is connected with a first port of the optical fiber circulator I, a second port of the optical fiber circulator I is used for being directly or indirectly connected with a head end of a first optical fiber to be detected of the photoelectric composite cable, the continuous light output end I is used for being directly or indirectly connected with a head end of a first transmission optical fiber, and an input end and an output end of the optical amplification module I are respectively used for being directly or indirectly connected with a tail end of the first transmission optical fiber and a tail end of the first optical fiber to be detected; the third port of the first optical fiber circulator is connected with the input end of the first signal processing and collecting module, and the first main control module is in communication connection with the first pulse continuous optical module, the first signal processing and collecting module and the first communication module to control the operation of each module; the second measurement system is provided with a second pulse continuous light generation module, a second signal processing and collecting module, a second communication module, a second main control module and a second optical amplification module; the second pulse continuous light module is provided with a second pulse output end and a second continuous light output end; the second pulse output end is connected with a first port of a second optical fiber circulator, a second port of the second optical fiber circulator is used for being directly or indirectly connected with the tail end of a second optical fiber to be detected of the photoelectric composite cable, the second continuous light output end is used for being directly or indirectly connected with the tail end of a second transmission optical fiber, and the input end and the output end of the second optical amplification module are respectively used for being directly or indirectly connected with the head end of the second transmission optical fiber and the head end of the second optical fiber to be detected; a third port of the second optical fiber circulator is connected with an input end of a second signal processing and collecting module, and the second main control module is in communication connection with the second pulse continuous optical module, the second signal processing and collecting module and the communication module to control the operation of each module; and the data inversion system is respectively in communication connection with the first communication module and the second communication module.
In addition, the long-distance high-resolution Brillouin optical time domain analyzer disclosed by the invention also has the following additional technical characteristics:
according to some embodiments of the present invention, the first signal processing and collecting module comprises a first photoelectric sensor, a first signal amplifying module and a first signal collecting module; and the signal processing and collecting module II comprises a photoelectric sensor II, a signal amplifying module II and a signal collecting module II.
According to some embodiments of the invention, the first optical amplification module is an erbium-doped fiber amplifier (EDFA) or a Raman Fiber Amplifier (RFA); and the second optical amplification module is an erbium-doped fiber amplifier (EDFA) or a Raman Fiber Amplifier (RFA).
According to some embodiments of the present invention, the measurement system further includes a first isolation module, an input end of the first isolation module is directly or indirectly connected to an output end of the first optical amplification module, and an output end of the first isolation module is used for being directly or indirectly connected to a tail end of the first optical fiber to be measured; the second measurement system further comprises a second isolation module, an input end of the second isolation module is directly or indirectly connected with an output end of the second optical amplification module, and an output end of the second isolation module is used for being directly or indirectly connected with a head end of the second optical fiber to be measured, as shown in fig. 2.
According to some embodiments of the invention, the first isolator and the second isolator employ fiber optic Isolators (ISO).
After the pulse light passes through the optical fiber to be detected, the pulse light is reversely cut off by the ISO, so that the direct current background of the pulse light with the limited extinction ratio cannot be transmitted into the transmission optical fiber through the ISO to act with the continuous light, the continuous light enters the optical fiber to be detected through the ISO in the forward direction and then is subjected to energy interaction with the pulse light, the generation of a non-local effect is effectively reduced, in addition, due to the existence of the ISO, the pulse light is cut off, the acquisition time of the signal processing acquisition module is reduced to half of the original acquisition time, and the measurement time is effectively shortened.
According to some embodiments of the present invention, the measurement system further includes a first filtering module, an input end of the first filtering module is directly or indirectly connected to an output end of the first optical amplifying module, and an output end of the first filtering module is used for being directly or indirectly connected to a tail end of the first optical fiber to be measured; the second measurement system further comprises a second filtering module, an input end of the second filtering module is directly or indirectly connected with an output end of the second optical amplification module, and an output end of the second filtering module is used for being directly or indirectly connected with a head end of the second optical fiber to be measured, as shown in fig. 2.
According to some embodiments of the invention, the first filtering module employs a Wavelength Division Multiplexer (WDM) or a Fiber Bragg Grating (FBG) module; and the second filtering module adopts a Wavelength Division Multiplexer (WDM) or a Fiber Bragg Grating (FBG) module.
The central wavelength of the filtering module is continuous optical wavelength, and when the optical amplification module adopts an EDFA, spontaneous emission ASE noise of the EDFA can be filtered; when the optical amplification module adopts the RFA, the Raman pump light of the RFA can be filtered, and the influence of noise is reduced.
According to some embodiments of the present invention, the optical amplifier further comprises a first host and a second host, wherein the first host comprises the first pulse continuous optical module, the first signal processing and collecting module, the first communication module, the first main control module and the second optical amplifying module; the second host comprises the second pulse continuous optical module, the second signal processing and collecting module, the second communication module, the second main control module and the first optical amplifying module, as shown in fig. 2.
According to some embodiments of the present invention, the first host further comprises a second isolator and a second filtering module; the second host further comprises the first isolator and the first filtering module, as shown in fig. 2.
According to some embodiments of the present invention, the measurement system further comprises a first laser and a first coupler; the first pulse continuous optical module is provided with a first pulse optical module and a first continuous optical module; the output end of the first laser is connected with the input end of the first coupler, and the two output ends of the first coupler are respectively connected with the first pulse light module and the first continuous light module; the second measurement system further comprises a second laser and a second coupler; the second pulse continuous optical module is provided with a second pulse optical module and a second continuous optical module; and the output end of the second laser is connected with the input end of the second coupler, and the two output ends of the second coupler are respectively connected with the second pulse light module and the second continuous light module.
According to some embodiments of the invention, the first host further comprises the first laser and the first coupler; the second host further comprises a second laser and a second coupler.
According to some embodiments of the present invention, the first continuous light module has a first microwave source and a first electro-optical modulator; the optical input end of the first electro-optical modulator is connected with one output end of the first coupler, and the electrical signal input end of the first electro-optical modulator is connected with the microwave source; the output end of the first electro-optical modulator is used for being directly or indirectly connected with the head end of the first transmission optical fiber; the continuous optical module II is provided with a microwave source II and an electro-optical modulator II; the optical input end of the second electro-optical modulator is connected with one output end of the second coupler, and the electrical signal input end of the second electro-optical modulator is connected with the microwave source; the output end of the electro-optical modulator II is used for being directly or indirectly connected with the tail end of the transmission optical fiber II; the first pulse light module is provided with a first pulse modulation unit; the pulse light module II is provided with a pulse modulation unit II.
According to some embodiments of the invention, the microwave source has a microwave amplitude of 10-14 GHz.
According to some embodiments of the present invention, the first continuous optical module further has a first optical amplifier and a first adjustable optical attenuator, an output end of the first electro-optical modulator is connected to an input end of the first optical amplifier, and an output end of the first optical amplifier is used for being directly or indirectly connected to a head end of the first transmission optical fiber; the second continuous optical module is also provided with a second optical amplifier and a second adjustable optical attenuator, the output end of the second electro-optical modulator is connected with the input end of the second optical amplifier, and the output end of the second optical amplifier is used for being directly or indirectly connected with the tail end of the second transmission optical fiber.
According to some embodiments of the present invention, the measurement system has a first frequency locking modulation module; the pulse continuous optical module I is provided with a pulse optical module I and a continuous optical module I, and the pulse optical module I is provided with a pulse laser I and a pulse modulation unit I; the first continuous optical module is provided with a first continuous optical laser, and the output end of the first continuous optical laser is used for being directly or indirectly connected with the head end of the first transmission optical fiber; the first frequency locking modulation module is respectively connected with the first pulse laser and the first continuous light laser; the second measurement system is provided with a second frequency locking modulation module; the pulse continuous optical module II is provided with a pulse optical module II and a continuous optical module II, and the pulse optical module is provided with a pulse laser II and a pulse modulation unit II; the second continuous optical module is provided with a second continuous light laser, and the output end of the second continuous light laser is used for being directly or indirectly connected with the tail end of the second transmission optical fiber; and the second frequency locking modulation module is respectively connected with the second pulse laser and the second continuous light laser.
According to some embodiments of the invention, the first pulse modulation unit is an electro-optical modulator (EOM) or an acousto-optical modulator (AOM) or a Semiconductor Optical Amplifier (SOA).
According to some embodiments of the present invention, the first continuous optical module further has a first optical amplifier and a first adjustable optical attenuator, an output end of the first continuous optical laser is connected to an input end of the first optical amplifier, an output end of the first optical amplifier is connected to an input end of the first adjustable optical attenuator, and an output end of the first adjustable optical attenuator is used for being directly or indirectly connected to a head end of the first transmission optical fiber; the continuous optical module II is also provided with a second optical amplifier and a second adjustable optical attenuator, the output end of the second laser for continuous light is connected with the input end of the second optical amplifier, the output end of the second optical amplifier is connected with the input end of the second adjustable optical attenuator, and the output end of the second adjustable optical attenuator is used for being directly or indirectly connected with the tail end of the second transmission optical fiber.
According to some embodiments of the present invention, the first pulse optical module further has a first optical amplifier, a first adjustable optical attenuator, and a first polarization scrambler, and the second pulse optical module further has a second optical amplifier, a second adjustable optical attenuator, and a second polarization scrambler.
According to some embodiments of the present invention, the first frequency-locked modulation module and the second frequency-locked modulation module are optical phase-locked modules (OPLLs).
Performing frequency locking at about 12GHz between the pulsed laser and the continuous light laser by using an optical phase locking module (OPLL); the laser emitted by the pulse laser is modulated by EOM/AOM/SOA to form pulse light.
According to some embodiments of the invention, the measurement system further comprises a pulsed 1 xn optical switch one and a continuous 1 xn optical switch one; the input end of the first pulse 1 xN optical switch is connected with the second port of the first optical fiber circulator, and the N output ends of the first pulse 1 xN optical switch are respectively used for being connected with the head ends of the first optical fibers to be tested of the N photoelectric composite cables; the input end of the first continuous 1 xN optical switch is connected with the output end of the first optical amplification module, and the N output ends of the first continuous 1 xN optical switch are respectively used for being connected with the tail ends of the N optical fibers to be detected; the second measurement system further comprises a second pulse 1 xN optical switch and a second continuous 1 xN optical switch; the input end of the pulse 1 xN optical switch II is connected with the second port of the optical fiber circulator II, and N output ends of the pulse 1 xN optical switch II are respectively used for being connected with the tail ends of the optical fibers II to be tested of the N photoelectric composite cables; the input end of the continuous 1 xN optical switch II is connected with the output end of the optical amplification module II, and N output ends of the continuous 1 xN optical switch II are respectively used for being connected with the head ends of N optical fibers II to be detected; the first main control module is in communication connection with the first pulse 1 xN optical switch and the second continuous 1 xN optical switch; the second main control module is in communication connection with the second pulse 1 × N optical switch and the first continuous 1 × N optical switch, as shown in fig. 2 and 3.
Switching of a pulse 1 xN optical switch and a continuous 1 xN optical switch is controlled through a main control module, so that the first pulse light to be detected and the first sweep continuous light to be detected are the same optical fiber, the first sweep continuous light to be detected and the second pulse light to be detected are the same optical fiber, the first pulse light to be detected and the second sweep continuous light to be detected are the same optical fiber, and the second pulse light to be detected are the same optical fiber respectively in the photoelectric composite cable, as shown in fig. 3. According to some embodiments of the present invention, the first host further comprises the pulsed 1 xn optical switch one and the continuous 1 xn optical switch two; the second host further comprises a second pulse 1 xN optical switch and a first continuous 1 xN optical switch.
According to one embodiment of the invention, the measurement distance is 80km (loop 160 km), each measurement system employs a single laser scheme, and laser one and laser two employ 1550.12nm narrow linewidth lasers (NKT Basik-Mikro-E15); the first coupler and the second coupler adopt a bias beam splitter PMISO; the first continuous optical module and the second continuous optical module respectively comprise a 12GHz microwave source, a 20GHz bandwidth electro-optic modulator (MX-LN-10), a continuous light amplification EDFA module and a Variable Optical Attenuator (VOA); the pulsed light module I and the pulsed light module II comprise a 200MHz AOM (T-M200-0.1C 2J-3-F2S), a pulsed light amplification EDFA module, a Variable Optical Attenuator (VOA) and a Polarization Scrambler (PS); the first optical amplification module and the second optical amplification module both adopt Raman amplifiers (BG-RFA-M-1450-500 mW-FC/APC); both the first filtering module and the second filtering module adopt 1450-1550 WDM (1450 nm and ASE noise is filtered); the first isolation module and the second isolation module both adopt 1550nm two-stage ISO; as shown in fig. 4, the abscissa represents the distance from the head end to the tail end of the photoelectric composite cable from left to right, and the measured data i has higher data accuracy at the head end and lower tail end accuracy at the head end of the photoelectric composite cable; the second measurement data is shown in fig. 5, the horizontal coordinate represents the distance from the tail end to the head end of the photoelectric composite cable from left to right, the second measurement data has higher data accuracy at the tail end of the photoelectric composite cable and lower head end accuracy; the first communication module of the first host and the second communication module of the second host send the first measurement data and the second measurement data to a data inversion system through a communication optical fiber network; the inversion system intercepts the first measured data from 0-46km on the abscissa as shown in fig. 4 as the first intercepted data, intercepts the second measured data from 0-34km on the abscissa as shown in fig. 5 as the second intercepted data, and then splices the first intercepted data and the second intercepted data to obtain the final measured data as shown in fig. 6.
Comparing fig. 4 and 5 with fig. 6, it can be seen that the overall accuracy of the final measurement data is high.
Any reference to "one embodiment," "an embodiment," "example embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention; the schematic representations in various places in the specification do not necessarily refer to the same embodiment; further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
While specific embodiments of the invention have been described in detail with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention; in particular, reasonable variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the foregoing disclosure, the drawings and the appended claims without departing from the spirit of the invention; except variations and modifications in the component parts and/or arrangements, the scope of which is defined by the appended claims and equivalents thereof.
Any reference to "one embodiment," "an embodiment," "example embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention; the schematic representations in various places in the specification do not necessarily refer to the same embodiment; further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments.
While specific embodiments of the invention have been described in detail with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention; in particular, reasonable variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the foregoing disclosure, the drawings and the appended claims without departing from the spirit of the invention; except variations and modifications in the component parts and/or arrangements, the scope of which is defined by the appended claims and equivalents thereof.

Claims (7)

1. A long-distance high-resolution Brillouin optical time domain analysis method is characterized by comprising the following steps of:
generating pulsed light I, pulsed light II, sweep-frequency continuous light I and sweep-frequency continuous light II;
the first pulse light is emitted from the head end of the first optical fiber to be detected of the photoelectric composite cable, and the second pulse light is emitted from the tail end of the second optical fiber to be detected of the photoelectric composite cable;
the sweep frequency continuous light I is emitted from the head end of the transmission optical fiber I, emitted from the tail end of the transmission optical fiber I and then emitted into the tail end of the optical fiber I to be detected through optical amplification, and the sweep frequency continuous light II is emitted from the tail end of the transmission optical fiber II, emitted from the head end of the transmission optical fiber II and then emitted into the head end of the optical fiber II to be detected through optical amplification;
the pulsed light I and the swept frequency continuous light I interact in the optical fiber I to be detected to form a probe light I, and the pulsed light II and the swept frequency continuous light II interact in the optical fiber II to be detected to form a probe light II;
collecting the light intensity of the first detection light and converting the light intensity into a first digital signal, and collecting the light intensity of the second detection light and converting the light intensity into a second digital signal;
calculating to obtain first measurement data from the head end to the tail end of the first optical fiber to be measured according to the first digital signal, and calculating to obtain second measurement data from the tail end to the head end of the second optical fiber to be measured according to the second digital signal;
and splicing the first measurement data and the second measurement data according to the precision of the first measurement data and the second measurement data to obtain final measurement data.
2. The method for analyzing the Brillouin optical time domain with the long distance and the high resolution according to claim 1, wherein the swept-frequency continuous light is optically amplified and then is emitted into the end of the first optical fiber to be measured through filtering; and the swept frequency continuous light II is subjected to optical amplification and then is subjected to filtering treatment and then is emitted into the head end of the optical fiber II to be detected.
3. The method for analyzing the Brillouin optical time domain with the long distance and the high resolution according to claim 1, wherein the swept-frequency continuous light is optically amplified and then emitted to the end of the first optical fiber to be measured through a one-way channel; and the swept frequency continuous light II is optically amplified and then is emitted into the head end of the optical fiber II to be detected through a one-way channel.
4. The method of claim 1, wherein the first 30-70% of data of the first measurement data is intercepted as first intercepted data from a head end of the optical-electrical composite cable, the remaining data in front of the second measurement data is intercepted as second intercepted data from a tail end of the optical-electrical composite cable, and the first intercepted data and the second intercepted data are spliced to obtain final measurement data.
5. The method according to claim 1, wherein the generating of the first pulse light, the second pulse light, the first swept-continuous light and the second swept-continuous light comprises:
dividing a laser beam into two beams, and dividing the laser beam into two beams;
one beam of the first laser beam is subjected to pulse modulation to form a first pulse light, and one beam of the second laser beam is subjected to pulse modulation to form a second pulse light;
and the other beam of the first laser forms the first swept-frequency continuous light through frequency sweeping, and the other beam of the second laser forms the second swept-frequency continuous light through pulse modulation.
6. The method according to claim 1, wherein the generating of the first pulse light, the second pulse light, the first swept-continuous light and the second swept-continuous light comprises:
pulse-modulating the pulse laser to form the pulse light I; one beam of the pulse laser II is subjected to pulse modulation to form pulse light II;
frequency locking between the first continuous light laser and the first pulse laser is performed to form the first swept continuous light; and the second continuous light laser passes through the frequency lock between the second pulse laser and the second continuous light laser to form the second swept continuous light.
7. A long-range high-resolution Brillouin optical time domain analysis method according to claim 1, it is characterized in that the number of the photoelectric composite cables is N, each photoelectric composite cable is provided with a first optical fiber to be tested and a second optical fiber to be tested, before the generation of the pulsed light I, the pulsed light II, the swept continuous light I and the swept continuous light II, the optical fiber I to be detected and the optical fiber I to be detected of the sweep frequency continuous light I which are injected into the pulse light I are the same optical fiber, the optical fiber II to be detected and the optical fiber II to be detected of the sweep frequency continuous light II which are injected into the pulse light I are the same optical fiber, and the optical fiber I to be detected and the optical fiber II to be detected which are injected into the pulse light II are respectively the same two optical fibers in the photoelectric composite cable by switching a plurality of 1 xN optical switches.
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