CN117387671A - Dual-wavelength microwave interference optical fiber sensing and positioning system and method based on loop-back link - Google Patents

Dual-wavelength microwave interference optical fiber sensing and positioning system and method based on loop-back link Download PDF

Info

Publication number
CN117387671A
CN117387671A CN202311427045.2A CN202311427045A CN117387671A CN 117387671 A CN117387671 A CN 117387671A CN 202311427045 A CN202311427045 A CN 202311427045A CN 117387671 A CN117387671 A CN 117387671A
Authority
CN
China
Prior art keywords
microwave
optical fiber
wavelength division
division multiplexer
sensing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202311427045.2A
Other languages
Chinese (zh)
Inventor
胡雨晗
李少波
王东杰
张磊
吕明阳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CETC 54 Research Institute
Original Assignee
CETC 54 Research Institute
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CETC 54 Research Institute filed Critical CETC 54 Research Institute
Priority to CN202311427045.2A priority Critical patent/CN117387671A/en
Publication of CN117387671A publication Critical patent/CN117387671A/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • G01D5/35306—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 an interferometer arrangement
    • G01D5/35322—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 an interferometer arrangement using interferometer with one loop with several directions of circulation of the light, e.g. Sagnac interferometer
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • 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
    • 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

Abstract

The invention provides a dual-wavelength microwave interference optical fiber sensing and positioning system and method based on a loop-back link, and belongs to the field of optical fiber sensing. The system comprises a system front end and a system tail end, wherein the system front end and the system tail end are respectively arranged at two ends of a sensing optical fiber: the front end of the system comprises a first transmitting module, a first receiving module, a second transmitting module, a second receiving module, a first wavelength division multiplexer and a second wavelength division multiplexer; the tail end of the system comprises a third wavelength division multiplexer, a fourth wavelength division multiplexer and a delay optical fiber. The invention utilizes the wavelength division multiplexing technology to fuse the microwave interference optical fiber sensor, realizes the distributed positioning of the microwave interference optical fiber sensing through the dual-wavelength loop optical fiber link, obtains the time delay quantity related to the disturbance occurrence position through the cross-correlation operation after carrying out signal processing on two phase signals, and further realizes the distributed disturbance positioning on the optical fiber sensing link. The invention solves the problem that a single microwave interference optical fiber sensor cannot realize distributed positioning.

Description

Dual-wavelength microwave interference optical fiber sensing and positioning system and method based on loop-back link
Technical Field
The invention belongs to the field of optical fiber sensing, and particularly relates to a dual-wavelength microwave interference optical fiber sensing positioning system and method based on a loop-back link.
Background
The distributed optical fiber sensor has the unique advantages of corrosion resistance, electromagnetic interference resistance, adaptation to extreme environments and the like, and can be applied to the fields of perimeter security, pipeline monitoring, earthquake detection and the like. The microwave interference optical fiber sensor uses the microwave photon technology to modulate the optical wave by using the intensity modulator, and realizes the optical fiber sensing by calculating the phase change quantity of the optical carrier microwave after transmission in the optical fiber link. Compared with the common optical fiber sensor based on light wave interference or light wave reflection, the microwave interference optical fiber sensor has the advantages of low cost, smaller influence by factors such as loss and dispersion in an optical fiber link and the like, and is suitable for application scenes such as submarine seismic monitoring. However, the existing microwave interference optical fiber sensor can only realize integral sensing, namely, the external disturbance information on the whole sensing link can only be monitored together, but can not realize disturbance distributed positioning.
Disclosure of Invention
In view of this, the present invention provides dual wavelength microwave interference fiber optic sensing and positioning systems and methods based on loop-back links. The invention utilizes the wavelength division multiplexing technology to fuse the microwave interference optical fiber sensors, realizes the distributed positioning of the microwave interference optical fiber sensing through the design of the dual-wavelength loop-back optical fiber link, and solves the problem that a single microwave interference optical fiber sensor cannot realize the distributed positioning.
The invention adopts the technical scheme that:
the dual-wavelength microwave interference optical fiber sensing and positioning system based on the loop-back link is used for positioning the interference position in the sensing optical fiber and comprises a system front end and a system tail end, wherein the system front end and the system tail end are respectively arranged at two ends of the sensing optical fiber:
the front end of the system comprises a first transmitting module, a first receiving module, a second transmitting module, a second receiving module, a first wavelength division multiplexer and a second wavelength division multiplexer; the first transmitting module is connected with the first receiving module, the second transmitting module is connected with the second receiving module, the first transmitting module and the second transmitting module are both connected with the first wavelength division multiplexer, and the first receiving module and the second receiving module are both connected with the second wavelength division multiplexer; the light wavelength of the first transmitting module and the first receiving module is lambda 1, and the light wavelength of the second transmitting module and the second receiving module is lambda 2, lambda 1 is not equal to lambda 2;
the tail end of the system comprises a third wavelength division multiplexer, a fourth wavelength division multiplexer and a delay optical fiber;
the first wavelength division multiplexer is connected with the third wavelength division multiplexer through a first sensing optical fiber, the second wavelength division multiplexer is connected with the fourth wavelength division multiplexer through a second sensing optical fiber, and the third wavelength division multiplexer and the fourth wavelength division multiplexer are also connected with each other through two independent optical fibers; the first sensing optical fiber and the second sensing optical fiber are two different fiber cores in the sensing optical cable.
Further, the first transmitting module and the second transmitting module have the same structure, and include: a narrow linewidth laser 12, an intensity modulator 13, a microwave signal source 14, a microwave power divider 15, a light emitting interface 16 and a microwave output interface 17; wherein, the light emitting interface 16 is used for connecting with the wavelength division multiplexer, the microwave output interface 17 is used for connecting with the receiving module;
in the transmitting module, a microwave signal output by a microwave signal source is split through a microwave power distributor, one path of the microwave signal is output through a microwave output interface and is provided for the receiving module, the other path of the microwave signal is transmitted to an intensity modulator, laser emitted by a narrow linewidth laser passes through the intensity modulator, an optical carrier microwave signal is generated based on the microwave signal transmitted by the microwave signal source, and the optical carrier microwave signal is output to a sensing optical fiber through an optical transmitting interface;
the first receiving module and the second receiving module have the same structure and comprise: a microwave phase shifter 18, a microwave mixer 19, a photoelectric detector 20, an analog-to-digital conversion card 21, a microwave input interface 22 and a light receiving interface 23; wherein, the light receiving interface 23 is used for connecting with the wavelength division multiplexer, the microwave input interface 22 is used for connecting with the transmitting module;
in the receiving module, the optical carrier microwave signal from the transmitting module is received through the microwave input interface, the optical carrier microwave signal is subjected to phase control through the microwave phase shifter and then is transmitted to the microwave mixer, in addition, the optical carrier microwave signal from the sensing optical fiber is received through the optical receiving interface, the optical carrier microwave signal is converted into a microwave signal through the photoelectric detector and then is transmitted to the microwave mixer, the microwave mixer mixes the microwave signal from the photoelectric detector with the microwave signal from the microwave phase shifter, and the mixed signal is converted into a digital signal through the analog-to-digital conversion card so as to be convenient for subsequent data processing.
The dual-wavelength microwave interference optical fiber sensing and positioning method based on the loop-back link comprises the following steps:
the front end and the tail end of the system as claimed in claim 1 are respectively arranged at two ends of the sensing optical fiber, and a sensing optical fiber link with a loop-back structure is constructed, wherein in the link, the same disturbance can generate twice phase modulation on light transmitted in the link;
let the disturbance arriving at the photodetector first beThe time difference between the two phase modulations is τ, the disturbance after reaching the photodetector is +.>The signal received by the photodetector in the first receiving module is:
lambda is set to 2 The time required for the transmission of light of wavelength in a delay fiber is denoted as τ 2 The signal received by the photodetector in the second receiving module is:
in data processing, R is as follows 1 For a period of time τ 2 Is shifted in time to obtain R 3 ：
From R 1 、R 2 、R 3 The following two signals are derived:
the two signals have constant time difference tau, and the cross-correlation function R is obtained by performing cross-correlation operation on the two signals xy ：
For R xy Searching peak, calculating the offset of the peak relative to the center position, and calculating the time difference tau;
the time for the disturbance to reach the tail end of the system is tau/2, and the length L of the disturbance from the tail end of the system is calculated according to tau x ：
Wherein n is the refractive index of the optical fiber, and c is the speed of light in vacuum;
and completing the distributed positioning of the disturbance.
The invention has the beneficial effects that:
1. the invention utilizes the wavelength division multiplexing technology to fuse the microwave interference optical fiber sensor, realizes the distributed positioning of the microwave interference optical fiber sensing through the design of a dual-wavelength loop optical fiber link, and obtains the time delay quantity related to the occurrence position of disturbance through the cross-correlation operation by carrying out signal processing on two phase signals, thereby realizing the distributed disturbance positioning on the optical fiber sensing link.
2. The invention solves the problem that a single microwave interference optical fiber sensor cannot realize distributed positioning.
Drawings
FIG. 1 is a block diagram of a dual wavelength distributed microwave interference fiber sensing and positioning system based on a loop-back link.
FIG. 2 is a schematic diagram of a configuration of a transmitting module used in the dual wavelength distributed microwave interference fiber sensing and positioning system based on a loop-back link of the present invention.
FIG. 3 shows a configuration of a receiving module used in the dual wavelength distributed microwave interference fiber optic sensing and positioning system based on a loop-back link according to the present invention.
FIG. 4 shows a disturbance signal R received by the dual-wavelength distributed microwave interference optical fiber sensing and positioning system based on a loop-back link 1 And R is R 2 Is a data map of (a).
FIG. 5 is a graph of X (t- τ) and Y (t) data calculated in the positioning algorithm of the dual wavelength distributed microwave interference fiber sensing positioning system based on the loop-back link of the present invention.
FIG. 6 is a schematic diagram of a cross-correlation function obtained in a positioning algorithm of the dual-wavelength distributed microwave interference optical fiber sensing positioning system based on a loop-back link.
Reference numerals in the drawings: 1. a first transmitting module; 2. a first receiving module; 3. a second transmitting module; 4. a second receiving module; 5. a first wavelength division multiplexer; 6. a second wavelength division multiplexer; 7. a third wavelength division multiplexer; 8. a fourth wavelength division multiplexer; 9. a delay optical fiber; 10. a first sensing optical fiber; 11. a second sensing optical fiber; 12. a narrow linewidth laser; 13. an intensity modulator; 14. a microwave signal source; 15. a microwave power divider; 16. an optical emission interface; 17. a microwave output interface; 18. a microwave phase shifter; 19. a microwave mixer; 20. a photodetector; 21. an analog-to-digital conversion card; 22. a microwave input interface; 23. an optical receiving interface.
Detailed Description
The invention will be described in further detail with reference to the accompanying drawings and examples of implementation.
A dual-wavelength microwave interference optical fiber sensing and positioning system based on a loop-back link has a structure shown in figure 1. It comprises the following steps:
front end of system: a first transmitting module 1, a first receiving module 2, a second transmitting module 3, a second receiving module 4, a first wavelength division multiplexer 5, a second wavelength division multiplexer 6;
sensing link: a first sensing optical fiber 10, a second sensing optical fiber 11;
system tail end: a third wavelength division multiplexer 7, a fourth wavelength division multiplexer 8, and a delay fiber 9;
fig. 2 shows a structure of a transmitting module, including: a narrow linewidth laser 12, an intensity modulator 13, a microwave signal source 14, a microwave power divider 15, a light emitting interface 16 and a microwave output interface 17;
fig. 3 shows a structure of a receiving module, including: the device comprises a microwave phase shifter 18, a microwave mixer 19, a photoelectric detector 20, an analog-to-digital conversion card 21, a microwave input interface 22 and a light receiving interface 23;
in the system, a single microwave interference optical fiber sensor is composed of a pair of transmitting modules and a pair of receiving modules. The functions of the transmitting module and the receiving module and the working principle of the microwave interference optical fiber sensor are described as follows:
in the transmitting module, laser emitted by the narrow linewidth laser passes through the intensity modulator to generate an optical carrier microwave signal, the optical carrier microwave signal is sourced from a microwave signal source, and finally the optical carrier microwave signal is output to the sensing optical fiber through the optical transmitting interface. Meanwhile, the microwave signals output by the microwave signal source are split through the microwave power distributor, one path is used for modulating the light waves, and the other path is output through the microwave output interface and is provided for the receiving module.
In the receiving module, a microwave signal from the transmitting module is received through a microwave input interface, and then the phase of the microwave signal is controlled through a microwave phase shifter so as to ensure the sensitivity of the sensing system. The optical receiving interface is used for receiving the optical carrier microwave signal from the sensing optical fiber, the photoelectric detector is used for converting the optical carrier microwave signal into a microwave signal, the microwave signal and the microwave signal from the microwave phase shifter are input into the microwave mixer for mixing, and the mixed signal is converted into a digital signal through the analog-to-digital conversion card so as to facilitate subsequent data processing.
Let the light emitted by the narrow linewidth laser be:
wherein A is the light amplitude, ω L In order to be the angular frequency of the light,is the optical phase. The intensity modulated laser light I 1 The method comprises the following steps:
wherein D is 1 Representing the DC component of light, A 1 The term is microwave term omega RF In order to be the angular frequency of the light,is the microwave phase. And the light returned from the sensing fiber optic link is:
where τ is the delay of light transmission in the sensing fiber link, expressed as:
where n is the refractive index of the fiber, L is the fixed length of the sensing fiber link, and c is the speed of light in vacuum. Delta L (t) is the change length of the sensing optical fiber link, and external stress, temperature and vibration are caused by the influence of photoelastic effectFactors such as the modulation of the phase of the transmitted light and the effect of photoelastic effect can be uniformly accounted for by DeltaL (t). Will I 2 The phase items which are fixed and unchanged in the phase are combined and recorded asThe amount of change in phase is denoted +.>The signal to be measured of the sensor is obtained. I via photoelectric detection 2 Comprises only I 2 The amplitude of the signal R is output by the photoelectric detector after DC removal out Expressed as:
microwave signal R output by microwave signal source and passing through phase shifter ref The method comprises the following steps:
wherein,is the phase after the phase shift of the microwave phase shifter. R is R out And R is R ref Mixing is carried out at a microwave mixer, microwave interference occurs, the microwave mixer outputs a low-pass filtered low-frequency signal, and the output R mix Expressed as:
by controlling the phase shifterAnd also consider->Typically a small signal, R mix The method comprises the following steps:
namely, the microwave interference optical fiber sensing is realized.
In the system, the sensing link is of a loop-back structure, namely, an optical carrier microwave signal is transmitted to the tail end of the system from the front end of the system through a first sensing optical fiber and is transmitted to the front end of the system from the tail end of the system through a second sensing optical fiber. At the tail end of the system, the first sensing optical fiber is connected with the first sensing optical fiber through the wavelength division multiplexer and the delay optical fiber, so that a loop back transmission link from the front end of the system to the tail end of the system and then to the front end of the system is formed. The first sensing optical fiber and the second sensing optical fiber are two different fiber cores of the same sensing optical cable, so that when disturbance acts on the sensing optical cable, the first sensing optical fiber and the second sensing optical fiber are subjected to phase modulation, and the modulated disturbance signals are basically the same.
In the system, the first transmitting module is connected with the first receiving module, and the wavelength of light transmitted and received by the first transmitting module is lambda 1. The second transmitting module is connected with the second receiving module, and the wavelength of light transmitted and received by the second transmitting module is lambda 2. And the two pairs of single sensors formed by the transmitting module and the receiving module are fused through a wavelength division multiplexing technology to form the dual-wavelength sensing system. The optical signals of lambda 1 and lambda 2 are multiplexed together through a first wavelength division multiplexer and input to a first sensing optical fiber, and the looped-back optical signals from a second sensing optical fiber are demultiplexed through a second wavelength division multiplexer and input to a first receiving module and a second receiving module respectively. At the tail end of the system, multiplexing and de-multiplexing are carried out through a third wavelength division multiplexer and a fourth wavelength division multiplexer, so that light with the wavelength of lambda 1 is directly looped back to the second sensing optical fiber from the first sensing optical fiber, and light with the wavelength of lambda 2 is looped back to the second sensing optical fiber after passing through the delay optical fiber from the first sensing optical fiber.
The distributed positioning method adopting the system comprises the following specific modes:
because the sensing optical fiber link is a loop-back structure, the same disturbance can generate two phase modulations on the light transmitted in the link, and the disturbance which reaches the photoelectric detector firstly is thatThe time difference between the two phase modulations is τ, the disturbance after reaching the photodetector is +.>The signal received by the photodetector in the first receiving module is:
lambda is set to 2 The time required for the transmission of light of wavelength in a delay fiber is denoted as τ 2 The signal received by the photodetector in the second receiving module is:
in data processing, R is as follows 1 For a period of time τ 2 Can then obtain R 3 ：
From R 1 、R 2 、R 3 The following two signals can be derived:
it can be seen that there is a constant time difference τ between the two signals. By performing cross-correlation operation on the two signals, a cross-correlation function R can be obtained xy ：
By reacting R xy And searching peak, and calculating the offset of the peak relative to the center position, so as to calculate tau. The time for the disturbance to reach the tail end of the system is tau/2, so that the length L of the disturbance from the tail end of the system can be obtained according to tau x ：
Where n is the refractive index of the fiber and c is the speed of light in vacuum. Obtaining L x The distributed positioning of the disturbance is completed.
The principle of the invention is as follows:
as shown in fig. 1, the light source wavelengths of the two emission modules in the system are all around 1550nm, but not exactly the same, so as to realize wavelength division multiplexing. One possible structure of the transmitting module is shown in fig. 2, and the transmitting module is used for injecting an optical carrier microwave signal into the sensing link, wherein the transmitting module mainly comprises a narrow linewidth laser, a microwave signal source and an intensity modulator, and the frequency of the microwave output by the microwave signal source can be set to be 10GHz. One possible configuration of the receiving module is shown in fig. 3, and functions to receive the optical carrier microwave signal from the sensing link, perform photoelectric conversion, and mix the original microwave signal from the transmitting module with the detected microwave signal, thereby obtaining the information of optical phase change in the link. Because the optical paths of the light with two wavelengths in the tail end of the system are different, the same phase change signal has different mathematical forms after reaching the photoelectric detector, and the distance between the disturbance occurrence position and the tail end of the system can be calculated by performing corresponding data processing on the signals with two wavelengths by utilizing the characteristic, so that the distributed positioning is realized. Computer simulation is carried out on the dual-wavelength positioning algorithm, the sampling rate of data acquisition is set to 500000Sa/s, the disturbance signal is a 500Hz sinusoidal signal, the disturbance occurrence position is 20km away from the tail end of the system, the length of the delay fiber is 20km, and then the signal R is 1 And R is R 2 As shown in the figure4. For R 1 And R is R 2 The data processing is performed such that X (t- τ) and Y (t) are identical in waveform but have a time delay as shown in FIG. 5. The cross-correlation function obtained by cross-correlating X (t- τ) with Y (t) is shown in FIG. 6, and the offset of the peak position of the cross-correlation function relative to the center position (500000) can be calculated to be 50, namely the time delay between X (t- τ) and Y (t) can be calculated to be 0.1ms, so that the distance L between the disturbance occurrence position and the tail end of the system can be calculated x And 20km, the disturbance positioning is realized.
In a word, the invention utilizes the dual-wavelength microwave interference optical fiber sensor to realize disturbance positioning on the loop-back optical fiber link, and can solve the problem that a single microwave interference optical fiber sensor cannot realize distributed positioning.

Claims (3)

1. The dual-wavelength microwave interference optical fiber sensing and positioning system based on the loop-back link is characterized by being used for positioning the interference position in the sensing optical fiber and comprising a system front end and a system tail end, wherein the system front end and the system tail end are respectively arranged at two ends of the sensing optical fiber:
the front end of the system comprises a first transmitting module, a first receiving module, a second transmitting module, a second receiving module, a first wavelength division multiplexer and a second wavelength division multiplexer; the first transmitting module is connected with the first receiving module, the second transmitting module is connected with the second receiving module, the first transmitting module and the second transmitting module are both connected with the first wavelength division multiplexer, and the first receiving module and the second receiving module are both connected with the second wavelength division multiplexer; the light wavelength of the first transmitting module and the first receiving module is lambda 1, and the light wavelength of the second transmitting module and the second receiving module is lambda 2, lambda 1 is not equal to lambda 2;
the tail end of the system comprises a third wavelength division multiplexer, a fourth wavelength division multiplexer and a delay optical fiber;
the first wavelength division multiplexer is connected with the third wavelength division multiplexer through a first sensing optical fiber, the second wavelength division multiplexer is connected with the fourth wavelength division multiplexer through a second sensing optical fiber, and the third wavelength division multiplexer and the fourth wavelength division multiplexer are also connected with each other through two independent optical fibers; the first sensing optical fiber and the second sensing optical fiber are two different fiber cores in the sensing optical cable.
2. The loop-back link based dual wavelength microwave interferometric fiber optic sensing and positioning system of claim 1, wherein the first and second transmitting modules are identical in structure, comprising: a narrow linewidth laser (12), an intensity modulator (13), a microwave signal source (14), a microwave power distributor (15), an optical emission interface (16) and a microwave output interface (17); wherein, the light emission interface (16) is used for connecting with the wavelength division multiplexer, the microwave output interface (17) is used for connecting with the receiving module;
in the transmitting module, a microwave signal output by a microwave signal source is split through a microwave power distributor, one path of the microwave signal is output through a microwave output interface and is provided for the receiving module, the other path of the microwave signal is transmitted to an intensity modulator, laser emitted by a narrow linewidth laser passes through the intensity modulator, an optical carrier microwave signal is generated based on the microwave signal transmitted by the microwave signal source, and the optical carrier microwave signal is output to a sensing optical fiber through an optical transmitting interface;
the first receiving module and the second receiving module have the same structure and comprise: the device comprises a microwave phase shifter (18), a microwave mixer (19), a photoelectric detector (20), an analog-to-digital conversion card (21), a microwave input interface (22) and a light receiving interface (23); wherein, the light receiving interface (23) is used for connecting with the wavelength division multiplexer, the microwave input interface (22) is used for connecting with the transmitting module;
in the receiving module, the optical carrier microwave signal from the transmitting module is received through the microwave input interface, the optical carrier microwave signal is subjected to phase control through the microwave phase shifter and then is transmitted to the microwave mixer, in addition, the optical carrier microwave signal from the sensing optical fiber is received through the optical receiving interface, the optical carrier microwave signal is converted into a microwave signal through the photoelectric detector and then is transmitted to the microwave mixer, the microwave mixer mixes the microwave signal from the photoelectric detector with the microwave signal from the microwave phase shifter, and the mixed signal is converted into a digital signal through the analog-to-digital conversion card so as to be convenient for subsequent data processing.
3. The dual-wavelength microwave interference optical fiber sensing and positioning method based on the loop-back link is characterized by comprising the following steps of:
the front end and the tail end of the system as claimed in claim 1 are respectively arranged at two ends of the sensing optical fiber, and a sensing optical fiber link with a loop-back structure is constructed, wherein in the link, the same disturbance can generate twice phase modulation on light transmitted in the link;
let the disturbance arriving at the photodetector first beThe time difference between the two phase modulations is τ, the disturbance after reaching the photodetector is +.>The signal received by the photodetector in the first receiving module is:
lambda is set to 2 The time required for the transmission of light of wavelength in a delay fiber is denoted as τ 2 The signal received by the photodetector in the second receiving module is:
in data processing, R is as follows 1 For a period of time τ 2 Is shifted in time to obtain R 3 ：
From R 1 、R 2 、R 3 The following two signals are derived:
the two signals have constant time difference tau, and the cross-correlation function R is obtained by performing cross-correlation operation on the two signals xy ：
For R xy Searching peak, calculating the offset of the peak relative to the center position, and calculating the time difference tau;
the time for the disturbance to reach the tail end of the system is tau/2, and the length L of the disturbance from the tail end of the system is calculated according to tau x ：
Wherein n is the refractive index of the optical fiber, and c is the speed of light in vacuum;
and completing the distributed positioning of the disturbance.
CN202311427045.2A 2023-10-31 2023-10-31 Dual-wavelength microwave interference optical fiber sensing and positioning system and method based on loop-back link Pending CN117387671A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311427045.2A CN117387671A (en) 2023-10-31 2023-10-31 Dual-wavelength microwave interference optical fiber sensing and positioning system and method based on loop-back link

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311427045.2A CN117387671A (en) 2023-10-31 2023-10-31 Dual-wavelength microwave interference optical fiber sensing and positioning system and method based on loop-back link

Publications (1)

Publication Number Publication Date
CN117387671A true CN117387671A (en) 2024-01-12

Family

ID=89462854

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202311427045.2A Pending CN117387671A (en) 2023-10-31 2023-10-31 Dual-wavelength microwave interference optical fiber sensing and positioning system and method based on loop-back link

Country Status (1)

Country Link
CN (1) CN117387671A (en)

Similar Documents

Publication Publication Date Title
US11193818B2 (en) Frequency modulation demodulator based on fiber grating sensor array
CN105136177B (en) The distribution type optical fiber sensing equipment and method of a kind of submillimeter spatial resolution
CN102506913B (en) Interference type optical fiber distribution disturbance sensor and disturbance location method thereof
CN103837188B (en) A kind of photodetector frequency response measurement device and measuring method thereof
CN110672137B (en) Interference type optical fiber vibration sensing system based on wavelength division multiplexing and microwave photon technology
CN102281107A (en) Dispersion measuring device and method for fiber optical device
CN102546007A (en) Device and method for realizing frequency measurement of multifrequency microwave signals by using Brillouin scattering
CN108614126B (en) Angular velocity measurement device and method based on wideband adjustable optical-electronic oscillator
CN113315573B (en) Optical-assisted broadband microwave instantaneous frequency measurement method
CN113098595B (en) Method, system and device for measuring group delay of few-mode optical fiber differential mode
CN104363047A (en) Light vector network analyzer system based on double-channel Mach-Zehnder modulator
CN108254062A (en) A kind of phase sensitive optical time domain reflection vibration detection device based on chaotic modulation
JPS63113323A (en) Optical detecting method and device thereof
CN105352446A (en) Sub-nano strain level multi-point multiplexing fiber grating quasi static strain sensor system
US11956016B2 (en) Hybrid sensing-communication optical system and method
CN115200691A (en) Few-mode optical fiber distributed acoustic sensing system and signal processing method thereof
CN205192442U (en) Ya na grade multiple spot multiplexed optical fiber grating quasi -state strain sensor system of meeting an emergency
RU2721739C1 (en) Fiber-optic instantaneous frequency measuring system of multiple microwave signals
CN101937602A (en) Multi-site optical fiber vibration invasion monitoring device
CN117387671A (en) Dual-wavelength microwave interference optical fiber sensing and positioning system and method based on loop-back link
Misbakhov Combined raman DTS and address FBG sensor system for distributed and point temperature and strain compensation measurements
CN209689740U (en) A kind of distribution type fiber-optic vibration measuring system
Jeon et al. Optical fiber chromatic dispersion measurement using bidirectional modulation of an optical intensity modulator
Hu et al. Dual wavelength microwave frequency fiber interferometer system for distributed localization based on time delay estimation
CN116972890B (en) Optical fiber sensor and modulation method thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination