CN114754855B - Dynamic remote pump distributed optical fiber vibration monitoring device for single light source pumping - Google Patents
Dynamic remote pump distributed optical fiber vibration monitoring device for single light source pumping Download PDFInfo
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- CN114754855B CN114754855B CN202210221107.3A CN202210221107A CN114754855B CN 114754855 B CN114754855 B CN 114754855B CN 202210221107 A CN202210221107 A CN 202210221107A CN 114754855 B CN114754855 B CN 114754855B
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- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
Abstract
The invention relates to the technical field of distributed optical fiber sensing, and provides a dynamic remote pump distributed optical fiber vibration monitoring device for single-light source pumping, which aims to solve the problems of insufficient signal-to-noise ratio and non-uniform optical amplification adjustment of long-distance distributed optical fiber vibration sensing, and comprises a first laser, a second laser, a detector, a computer, a plurality of optical fibers to be detected, a multi-channel adjustable optical attenuator, a plurality of transmission optical fibers and a plurality of remote pump modules; the invention uses the pumping light output by the second laser as the pumping light source of erbium-doped optical fiber amplification, raman amplification and remote pump amplification. Meanwhile, the problem of uneven optical signal distribution in the traditional optical amplification scheme is compensated by utilizing the combined configuration of a plurality of cascaded remote pump modules and a multi-channel adjustable optical attenuator, so that a longer sensing distance and a higher signal-to-noise ratio are realized.
Description
Technical Field
The invention relates to the technical field of distributed optical fiber sensing, in particular to a dynamic remote pump distributed optical fiber vibration monitoring device for single-light source pumping.
Background
Distributed optical fiber vibration sensing technology represented by phase sensitive optical time domain reflectometer (phi-OTDR) is widely studied for its characteristics of long distance and large-range monitoring. The huge loss of optical signals caused by long-distance transmission becomes a main factor for restricting a long-distance distributed optical fiber vibration sensing system, and the problems of reduced spatial resolution or reduced signal-to-noise ratio of the system caused by nonlinear effect exist in a mode of increasing pulse light width or increasing pulse light fiber entering power to prolong the sensing distance of the phi-OTDR system.
Therefore, the optical amplification technology is adopted in the phi-OTDR system, so that the system sensing distance can be prolonged while the system spatial resolution is ensured. However, in the conventional optical amplification technical scheme represented by raman pumping amplification and brillouin pumping amplification, the problem of uneven optical signal distribution still exists, meanwhile, the use of multiple types of pumping light sources is not beneficial to the adjustment of the optical amplification performance of a system, and finally, the problem of nonlinear effect can be caused by excessively high signal optical power, and the problem of insufficient signal-to-noise ratio can exist in excessively low signal optical power.
Therefore, the dynamic remote pump amplification technology of single light source pumping is adopted, the problems of uneven distribution of optical signals and non-uniform adjustment of optical amplification can be solved, the method has important significance for improving portability, practicality and suitability of the distributed optical fiber vibration sensing system, and the long-distance distributed vibration sensing system is more close to a real practical product, so that important economic value and social value are generated.
Disclosure of Invention
The invention provides a dynamic remote pump distributed optical fiber vibration monitoring device of single light source pumping, which aims to solve the problems of insufficient signal-to-noise ratio and non-uniform optical amplification adjustment of long-distance distributed optical fiber vibration sensing. The invention uses a single pumping light source with the wavelength of 1480nm as the pumping light source of erbium-doped optical fiber amplification, raman amplification and remote pump amplification in the system. Meanwhile, the problem of uneven optical signal distribution in the traditional optical amplification scheme is compensated by utilizing the combined configuration of a plurality of cascaded remote pump modules and a multi-channel adjustable optical attenuator, so that a longer sensing distance and a higher signal-to-noise ratio are realized.
In order to solve the technical problems, the invention adopts the following technical scheme: a dynamic remote pump distributed optical fiber vibration monitoring device of single light source pumping comprises a first laser, a second laser, a detector, a computer, a plurality of optical fibers to be tested, a multi-channel adjustable optical attenuator, a plurality of transmission optical fibers and a plurality of remote pump modules;
the laser emitted by the first laser is divided into two beams by a first light splitter, one beam is used as local light to be incident to a first optical fiber coupler, the other beam is used as detection light to be modulated into pulse light by an acousto-optic modulator, the pulse light is sequentially connected with a plurality of optical fibers to be detected after passing through an a port and a b port of a first circulator and a first wavelength division multiplexer, a remote pump module is connected between the two connected optical fibers to be detected, and the last optical fiber to be detected is connected with an optical isolator;
the laser emitted by the second laser is used as pumping light to be divided into a plurality of beams, wherein one beam of the laser is subjected to Raman amplification in an optical fiber to be tested connected with the first wavelength division multiplexer, the second beam of the laser is divided into a plurality of beams by a multi-channel adjustable optical attenuator, and each beam of the laser is respectively connected with the pumping signal input end of one remote pump module after passing through the transmission optical fiber;
the remote pump module comprises a second circulator, a second wavelength division multiplexer, a first erbium-doped optical fiber, a third circulator, a second optical fiber coupler, a third wavelength division multiplexer and a second erbium-doped optical fiber; the port a of the second circulator is connected with the second end of the former optical fiber to be tested, the port b is connected with the port a of the second wavelength division multiplexer, the port c is connected with the port a of the third wavelength division multiplexer, the port c of the second wavelength division multiplexer is connected with the port a of the third circulator through the first erbium-doped optical fiber, the port c of the third wavelength division multiplexer is connected with the port c of the third circulator through the second erbium-doped optical fiber, and the port b of the third circulator is used as the output end of the remote pump module to be connected with the latter optical fiber to be tested; the input end of the second optical fiber coupler is used as a pumping signal input end and is used for dividing the pumping signal output by the multi-channel adjustable optical attenuator into two beams, one beam is output to the b port of the second wavelength division multiplexer, the pulse light output in the previous optical fiber to be tested is amplified through the first erbium-doped optical fiber, the other beam is output to the b port of the third wavelength division multiplexer, and the backward Rayleigh scattering signal entering the second erbium-doped optical fiber is amplified;
the c port of the first circulator is connected with a first optical fiber coupler after passing through an optical filter, the first optical fiber coupler is used for combining local light and a backward Rayleigh scattering signal output from the c port of the first circulator and then sending the combined light to the detector, and the computer is connected with the detector and is used for calculating and obtaining vibration information in each optical fiber to be detected according to a detection signal of the detector.
The pulse optical amplifier comprises a fourth wavelength division multiplexer and a third erbium-doped optical fiber, wherein an a port of the fourth wavelength division multiplexer is connected with the acousto-optic modulator, a c port of the fourth wavelength division multiplexer is connected with one end of the third erbium-doped optical fiber, a b port of the fourth wavelength division multiplexer is connected with a third beam of laser emitted by the second laser, and the other end of the third erbium-doped optical fiber is connected with an a end of the first circulator.
The first laser is a narrow linewidth laser with a wavelength of 1550nm and the second laser has a wavelength of 1480nm.
The length of the transmission optical fiber connected with each remote pump module is equal to the sum of the lengths of the optical fibers to be measured positioned at the proximal ends of the corresponding remote pump modules.
The four optical fibers to be tested are respectively a first optical fiber to be tested, a second optical fiber to be tested, a third optical fiber to be tested, a fourth optical fiber to be tested and a third optical fiber to be tested, and the remote pump modules comprise three remote pump modules which are respectively a first remote pump module, a second remote pump module and a third remote pump module; the first optical fiber to be tested, the first remote pump module, the second optical fiber to be tested, the second remote pump module, the third optical fiber to be tested, the third remote pump module and the fourth optical fiber to be tested are connected in sequence;
the multi-channel adjustable optical attenuator divides pumping light signals into three beams, wherein one beam is connected with a first remote pump module through the first transmission optical fiber, the other beam is connected with a second remote pump module through the second transmission optical fiber, the third beam is connected with a third remote pump module through the third transmission optical fiber, the length of the first transmission optical fiber is equal to the first optical fiber to be measured, the length of the second transmission optical fiber is equal to the sum of the first optical fiber to be measured and the second optical fiber to be measured, and the length of the third transmission optical fiber is equal to the sum of the first optical fiber to be measured, the second optical fiber to be measured and the third optical fiber to be measured.
The first optical fiber coupler is an optical fiber coupler with a light splitting ratio of 90:10, wherein 90% of the optical fiber coupler is used as detection light, 10% of the optical fiber coupler is used as local light, and the second optical fiber coupler is an optical fiber coupler with a light splitting ratio of 50:50.
The control end of the multi-channel adjustable optical attenuator is connected with the computer, and the computer is also used for controlling the power of each output end of the multi-channel adjustable optical attenuator so as to control the pumping signals input in each remote pump module.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention uses single light source pump as the pump light source of erbium-doped fiber amplification, raman amplification and remote pump amplification in the system to construct the mixed light amplification structure, thereby avoiding the problem of spontaneous radiation noise superposition caused by the traditional light amplification scheme, facilitating the linkage adjustment of multiple types of light amplification devices, realizing optimized light amplification gain output and improving the signal to noise ratio of the system.
2. According to the invention, a cascade remote pump amplification technology is utilized, remote pump modules are arranged in sections to realize multi-stage amplification of 1550 nm-band optical signals, so that the problem of uneven optical signal distribution caused by optical amplification technologies such as erbium-doped optical fiber amplification, raman amplification, brillouin amplification and the like in a traditional scheme is solved, the signal-to-noise ratio of a system is improved, and long-distance distributed optical fiber vibration sensing detection is realized.
3. According to the invention, the power of 1480nm pump light in the cascade remote pump module is dynamically regulated by utilizing the multichannel adjustable optical attenuator, and the power proportion of the multi-section remote pump module is uniformly regulated, so that the nonlinear effect problem caused by the excessively high signal light power and the signal-to-noise ratio deficiency problem caused by the excessively low signal light power are avoided, and the flatness of the all-fiber light power is comprehensively improved.
Drawings
FIG. 1 is a schematic diagram of a dynamic remote pump distributed optical fiber vibration monitoring device for single light source pumping according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a remote pump module according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a dynamic remote pump distributed optical fiber vibration monitoring device for single-light source pumping according to a second embodiment of the present invention;
in the figure, 1, a first laser, 2, a first optical splitter, 3, an acousto-optic modulator, 4, a signal generator, 5, a fourth wavelength division multiplexer, 6, a third erbium-doped optical fiber, 7, a first circulator, 8, a first wavelength division multiplexer, 9, a first optical fiber to be tested, 10, a second circulator, 11, a second wavelength division multiplexer, 12, a first erbium-doped optical fiber, 13, a third circulator, 14, a second optical fiber to be tested, 15, a pulse optical amplifier, 19, a third optical fiber to be tested, 24, a fourth optical fiber to be tested, 25, an optical isolator, 26, an optical filter, 27, a first optical fiber coupler, 28, a detector, 29, a computer, 30, a second laser, 31, a multichannel adjustable optical attenuator, 32, a first transmission optical fiber, 33, a second optical fiber coupler, 34, a third wavelength division multiplexer, 35, a second erbium-doped optical fiber, 36, a second transmission optical fiber, 41, a third transmission optical fiber, 47, a first telepump, 48, a telepump module, a tele-pump module, 49 and a tele-pump module.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments; all other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
As shown in fig. 1, a first embodiment of the present invention provides a dynamic remote pump distributed optical fiber vibration monitoring device for single-light source pumping, which includes a first laser 1, a second laser 30, a detector 28, a computer 29, a multi-channel tunable optical attenuator 31, a first optical fiber to be measured 9, a second optical fiber to be measured 14, a third optical fiber to be measured 19, a fourth optical fiber to be measured 24, a first remote pump module 47, a second remote pump module 48, a third remote pump module 49, a first transmission optical fiber 32, a second transmission optical fiber 36, and a third transmission optical fiber 41.
The laser beam emitted by the first laser 1 is split into two beams after passing through the first beam splitter 2, one beam is used as local light to be incident to the first optical fiber coupler 27, the other beam is used as probe light to be modulated into pulse light by the acousto-optic modulator 3, the pulse light passes through the pulse light amplifier 15, and then passes through the port and the port b of the first circulator 7a and the port b and the first wavelength division multiplexer 8 to be sequentially connected with the first optical fiber 9 to be tested, the first remote pump module 47, the second optical fiber 14 to be tested, the second remote pump module 48, the third optical fiber 19 to be tested, the third remote pump module 49, the fourth optical fiber 24 to be tested and the optical isolator 25.
The laser light emitted by the second laser 30 is split into multiple beams as pumping light, one beam of the pumping light is raman amplified by the first wavelength division multiplexer 8 and then the pulse light in the optical fiber 9 to be tested connected with the first wavelength division multiplexer, the second beam of the pumping light is split into multiple beams by the multi-channel adjustable optical attenuator 31, and each beam of the pumping light is respectively connected with the pumping signal input end of one remote pump module after passing through one transmission optical fiber. For example, one of the bundles is connected to the pump signal input of the first remote pump module 47 via the first transmission fiber 32, the other bundle is connected to the pump signal input of the second remote pump module 48 via the second transmission fiber 36, and the third bundle is connected to the pump signal input of the third remote pump module 48 via the third transmission fiber 41.
In this embodiment, the first remote pump module 47, the second remote pump module 48, and the third remote pump module 49 have the same structure, and as shown in fig. 2, the first remote pump module includes a second circulator 10, a second wavelength division multiplexer 11, a first erbium-doped fiber 12, a third circulator 13, a second fiber coupler 33, a third wavelength division multiplexer 34, and a second erbium-doped fiber 35. In each remote pump module, the a port of the second circulator 10 is a pulse signal input end and a backward Rayleigh scattering signal output end, and is connected with the optical fiber to be measured at the previous stage, and the b port of the third circulator 13 is a pulse signal output end and a backward Rayleigh scattering signal input end, and is connected with the optical fiber to be measured at the next stage.
Taking the first remote pump module 47 as an example, wherein the a port of the second circulator 10 is used as a pulse signal input end to be connected with the second end of the first optical fiber 9 to be tested, the b port of the second circulator 10 is connected with the a port of the second wavelength division multiplexer 11, the c port of the second wavelength division multiplexer 11 is connected with the a port of the third wavelength division multiplexer 34, the c port of the second wavelength division multiplexer 11 is connected with the a port of the third circulator 13 through the first erbium-doped optical fiber 12, the c port of the third wavelength division multiplexer 34 is connected with the c port of the third circulator 13 through the second erbium-doped optical fiber 35, and the b port of the third circulator 13 is used as a pulse signal output end of the first remote pump module 47 to be connected with the first end of the second optical fiber 14 to be tested; the input end of the second optical fiber coupler 33 is used as a pumping signal input end, and is used for dividing the pumping signal output by the multi-channel adjustable optical attenuator 31 into two beams, wherein one beam is output to the b port of the second wavelength division multiplexer 11, the pulse light output by the first optical fiber 9 to be tested is subjected to erbium-doped optical fiber amplification through the first erbium-doped optical fiber 12, the other beam is output to the b port of the third wavelength division multiplexer 34, and the backward Rayleigh scattering signal entering the second erbium-doped optical fiber 35 through the c port of the third circulator 13 is subjected to erbium-doped optical fiber amplification; the c port of the first circulator 7 is connected with a first optical fiber coupler 27 after passing through an optical filter 26, the first optical fiber coupler 27 is used for combining local light and a backward Rayleigh scattering signal output from the c port of the first circulator 7 and then sending the combined light to the detector 28, and the computer 29 is connected with the detector 28 and is used for calculating and obtaining vibration information in each optical fiber to be tested according to detection signals of the detector 28.
Specifically, in this embodiment, the first laser 1 is a narrow linewidth laser with a wavelength of 1550nm, and the second laser 30 is a multiplexed output laser with a wavelength of 1480nm. The wavelength can make the laser output by the second laser 30 meet the pumping condition, so that the laser can amplify 1550nm pulse light in the first erbium-doped optical fiber 12 and then enter the optical fiber to be measured of the next stage, and at the same time, can amplify backward Rayleigh scattered light generated in the optical fiber to be measured of the next stage in the second erbium-doped optical fiber 35, thereby improving the signal to noise ratio of the measurement signal.
Further, in this embodiment, the first optical splitter 2 is an optical fiber coupler with a splitting ratio of 90:10, wherein 90% is used as the probe light, 10% is used as the local light, and the second optical fiber coupler 33 is an optical fiber coupler with a splitting ratio of 50:50. The splitting ratio of the first splitter 2 and the second fiber coupler 33 can also be adjusted according to actual needs.
Specifically, as shown in fig. 1, in this embodiment, the a-port and the b-port of the first wavelength division multiplexer 8, the second wavelength division multiplexer 11, and the third wavelength division multiplexer 34 are located at one end, and the c-port is located at the other end, where the wavelength of the a-port is 1550nm, the wavelength of the b-port is 1480nm, and the wavelength of the c-port is 1550/1480nm.
Specifically, in the present embodiment, the transmission directions of the optical signals in the first circulator 7, the second circulator 10, and the third circulator 13 are as follows: a-port-b-port-c-port.
Further, in this embodiment, the length of the transmission fiber connected to each remote pump module is equal to the sum of the lengths of the optical fibers to be measured at the proximal end of the corresponding remote pump module, that is, the length of the first transmission fiber 32 is equal to the first optical fiber to be measured 9, the length of the second transmission fiber 36 is equal to the sum of the first optical fiber to be measured 9 and the second optical fiber to be measured 14, and the length of the third transmission fiber 41 is equal to the sum of the first optical fiber to be measured 9, the second optical fiber to be measured 14, and the third optical fiber to be measured 19.
Further, in this embodiment, the control end of the multi-channel variable optical attenuator 31 is connected to the computer 29, and the computer is further configured to control the power of each output end of the multi-channel variable optical attenuator 31 to control the pump signal input in each remote pump module. In addition, the b port of the computer is connected with the control end of the second laser 30, and the output control signal thereof controls the pumping laser signal output of the second laser 30.
Example two
As shown in fig. 3, a second embodiment of the present invention provides a dynamic remote pump distributed optical fiber vibration monitoring device for single-light source pumping, which has a structure substantially the same as that of the first embodiment, and includes a first laser 1, a second laser 30, a detector 28, a computer 29, a multi-channel tunable optical attenuator 31, four optical fibers to be tested, three transmission fibers and three remote pump modules. Unlike the first embodiment, in this embodiment, the pulsed optical amplifier includes a fourth wavelength division multiplexer 5 and a third erbium-doped fiber 6, where an a port of the fourth wavelength division multiplexer 5 is connected to the acousto-optic modulator 3, a c port of the fourth wavelength division multiplexer 5 is connected to one end of the third erbium-doped fiber 6, a b port of the fourth wavelength division multiplexer is connected to a third beam of laser light emitted by the second laser 30, and another end of the third erbium-doped fiber 6 is connected to an a end of the first circulator 7.
Specifically, in this embodiment, the first laser 1 is a narrow linewidth laser with a wavelength of 1550nm, and the second laser 30 is a multiplexed output laser with a wavelength of 1480nm. The wavelength can make the laser output by the second laser 30 meet the pumping condition, so that the laser can amplify 1550nm pulse light in the first erbium-doped optical fiber 12 in each remote pump module and then make the amplified pulse light enter the next-stage optical fiber to be measured, and at the same time, can amplify backward Rayleigh scattered light generated in the next-stage optical fiber to be measured in the second erbium-doped optical fiber 35, thereby improving the signal-to-noise ratio of the measurement signal.
In this embodiment, the pump light emitted by the second laser 30 is split into a part, and coupled into the third erbium-doped fiber 6 together with the pulse light by the fourth wavelength division multiplexer 5, so as to provide the pump signal light for the third erbium-doped fiber 6, and the pulse light modulated by the acousto-optic modulator 3 can be amplified.
Further, in this embodiment, the first optical splitter 2 is an optical fiber coupler with a splitting ratio of 90:10, wherein 90% is used as the probe light, 10% is used as the local light, and the second optical fiber coupler 33 is an optical fiber coupler with a splitting ratio of 50:50.
Further, in this embodiment, the control end of the multi-channel variable optical attenuator 31 is connected to the computer 29, and the computer is further configured to control the power of each output end of the multi-channel variable optical attenuator 31 to control the pump signal input in each remote pump module. In addition, the b port of the computer is connected with the control end of the second laser 30, and the output control signal thereof controls the pumping laser signal output of the second laser 30.
Specifically, as shown in fig. 1, in this embodiment, the first wavelength division multiplexer 8, the second wavelength division multiplexer 11, the third wavelength division multiplexer 34, and the fourth wavelength division multiplexer 5 are located at one end, the a port and the b port are located at the other end, where the wavelength of the a port is 1550nm, the wavelength of the b port is 1480nm, and the wavelength of the c port is 1550/1480nm. In the present embodiment, the transmission directions of the optical signals in the first circulator 7, the second circulator 10, and the third circulator 13 are: a-port-b-port-c-port.
In this embodiment, the pulse signal output from the acousto-optic modulator 3 can be amplified by splitting the pump light signal output from the second laser 30 into one beam and coupling the beam into the third erbium-doped fiber 6 through the fourth wavelength division multiplexer 5.
The working principle of the invention is as follows:
1. the first laser 1 emits continuous narrow linewidth laser with the center wavelength of 1550nm, the continuous narrow linewidth laser is divided into two parts with the power ratio of 90% and 10% by the first optical splitter 2, and after the 10% laser is output from the c port of the first optical splitter 2 as local light, the laser is connected to the a input end of the first optical fiber coupler 27; 90% of laser is output from a b port of the first optical splitter 2 as detection light and then is input into the acousto-optic modulator 3, the signal generator 4 is connected with a modulation signal input end of the acousto-optic modulator 3 and provides pulse signals with periodically alternating high peak power and low peak power for the acousto-optic modulator, and the acousto-optic modulator 3 modulates continuous detection light into pulse light under the driving of the signal generator 4 and generates frequency shift of 200 MHz; the modulated pulse light is output from the acousto-optic modulator 3 to the port a of the fourth wavelength division multiplexer 5; the b output end of the second laser 30 outputs 1480nm pump light to the b input end of the fourth wavelength division multiplexer 5, and the pulse optical signal and 1480nm pump light are output to the input end of the third erbium-doped optical fiber 6 through the c port of the fourth wavelength division multiplexer 5, so that the pulse signal light amplification is realized; the amplified pulse optical signal is input to an a port of the first wavelength division multiplexer 8 through an a port and a b port of the first circulator 7; the c output end of the second laser 30 outputs 1480nm pump light to the b port of the first wavelength division multiplexer 8 as a high-power pump source for raman amplification of the system, and the c port of the first wavelength division multiplexer 8 is connected to the input end of the optical fiber 9 to be tested, and the pump light signal and the pulse light signal are input into each optical fiber to be tested. And the vibration signal applied to the optical fiber to be detected is used for detecting and identifying the system. The pulse optical signal is output through the isolator 25 after passing through the first optical fiber 9 to be tested, the first remote pump module 47, the second optical fiber 14 to be tested, the second remote pump module 48 … … and then analogizing to the fourth optical fiber 24 to be tested. The backward Rayleigh scattering signal generated in the fourth optical fiber 24 to be tested returns to the c port of the first wavelength division multiplexer 8 after passing through the third remote pump module 49, the second optical fiber 19 to be tested, the second remote pump modules 48 and … … in sequence, then enters the b port of the first circulator 7 after passing through the a port of the first wavelength division multiplexer 8 in sequence, and enters the detector 28 after being output from the c port of the first circulator 7, passes through the 1550nm optical filter 26 and the first optical fiber coupler 27, and enters the detector 28 together with 10% of local light. And (3) after the signals detected by the detector are calculated by a computer, obtaining vibration signals in each optical fiber to be detected.
2. The pump light output by the d port of the second laser 30 is attenuated by the multi-channel adjustable optical attenuator 31, and then is divided into multiple beams to be input into each remote pump module, and the pulse light signal and the backward rayleigh scattering light signal in each remote pump module are amplified respectively.
3. In the first remote pump module 47, the a port of the second circulator 10 receives the pulse light output from the previous optical fiber 9 to be tested, and then the pulse light is output from the b port of the second circulator 10 and then is incident to the a input end of the second wavelength division multiplexer 11; the a port of the second optical fiber coupler 33 receives the pump light signal through the first transmission optical fiber 32, then outputs the pump light signal to the b port of the second wavelength division multiplexer 11 through the b port, the c port of the second wavelength division multiplexer 11 couples the 1480nm pump light signal with the pulse light signal input by the b output end of the second circulator 10, inputs the pulse light signal to the input end of the second erbium-doped optical fiber 12 for second-stage optical amplification, and sends the amplified signal to the next-stage optical fiber to be tested and the remote pump module after passing through the a port and the b port of the third circulator 13; similarly, the second remote pump module 48 and the third remote pump module 49 sequentially amplify the pulse signal after passing through the optical fiber to be tested. The optical signal amplified by the fourth stage is unidirectionally transmitted through the fourth optical fiber 24 to be measured of the last stage, and the optical signal is input to the input end of the optical isolator 25, where the optical isolator 25 is used for preventing reflected laser from affecting the backward scattering signal.
4. In the third remote pump module 49, the b port of the third circulator 13 receives the backward rayleigh scattering signal output by the fourth fiber 24 to be tested, then the signal is output from the c port of the third circulator 13 to the second erbium-doped fiber 35, the b port of the third wavelength division multiplexer 34 receives the pumping light signal output by the c port of the second fiber coupler 33, the pumping light signal is output from the c port and then is sent to the second erbium-doped fiber 35, then the backward rayleigh scattering signal is subjected to first-stage amplification in the second erbium-doped fiber 35, the amplified backward rayleigh scattering signal enters the c port of the second circulator 10 after passing through the c port and the a port of the third wavelength division multiplexer 34, then returns to the third fiber 19 to be tested and the second remote pump module 48 from the c port and the a port of the second circulator 10 in sequence, and similarly, the second remote pump module 48 and the first remote pump module 47 sequentially amplify the backward rayleigh scattering signal at the second stage and the third stage, then returns to the first wavelength division multiplexer 8 after passing through the first fiber 9 to be tested, and finally enters the first optical filter 27 and the first remote multiplexer 27 and the first optical filter 27.
In addition, it should be noted that, although the above embodiment only provides an explanation of amplifying the distributed optical fiber to be measured by three remote pump modules, according to the teachings of the embodiments of the present invention, a person skilled in the art may adjust the number of remote pump modules and the distribution situation of the optical fiber to be measured according to the actual measurement needs, for example, set five optical fibers to be measured and four remote pump modules, where one remote pump module is distributed between each optical fiber to be measured.
In summary, the present invention provides a dynamic remote pump distributed optical fiber vibration monitoring device for single light source pumping, which uses multiple paths of laser signals output by the second laser 30, one beam provides pumping signal light for the third erbium-doped fiber 6, and further uses the pumping signal light as EDFA of the preamplifier to amplify the pulse signal light; the other beam is coupled into a first optical fiber 9 to be tested through a first wavelength division multiplexer 8, so that Raman amplification of pulse optical signals in the optical fiber to be tested is realized, and the optimal signal transmission of the pre-amplification of the pulse optical signals can be realized through proportioning of two paths of 1480nm pump light; the third beam is connected with the multi-channel adjustable attenuator 31, the multi-channel adjustable attenuator 31 divides the pumping light signals into a plurality of beams, the pumping light signals are respectively input into a remote pump module 47 through a transmission optical fiber, and the plurality of remote pump modules are connected in series to realize multi-stage remote pump amplification; the c output end of the computer 29 is connected with the a input end of the multi-channel adjustable optical attenuator 31 to control the power of the 1480nm pump light injected into each remote pump module, and the signal-to-noise ratio of the vibration signal to be tested is improved according to the difference of the signal to be tested.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (7)
1. The dynamic remote pump distributed optical fiber vibration monitoring device for single-light source pumping is characterized by comprising a first laser (1), a second laser (30), a detector (28), a computer (29), a plurality of optical fibers to be tested, a multi-channel adjustable optical attenuator (31), a plurality of transmission optical fibers and a plurality of remote pump modules;
the laser emitted by the first laser (1) is divided into two beams by a first beam splitter (2), one beam is used as local light to be incident to a first optical fiber coupler (27), the other beam is used as detection light to be modulated into pulse light by an acousto-optic modulator (3), the pulse light is sequentially connected with a plurality of optical fibers to be detected by a first circulator (7) a port and b port and a first wavelength division multiplexer (8) after passing through a pulse light amplifier (15), a remote pump module (47) is connected between the two optical fibers to be detected, and the last optical fiber to be detected is connected with an optical isolator (25);
the laser emitted by the second laser (30) is used as pumping light to be divided into a plurality of beams, wherein one beam carries out Raman amplification on pulse light in an optical fiber to be tested connected with the first wavelength division multiplexer (8), the second beam is divided into a plurality of beams by a multi-channel adjustable optical attenuator (31), and each beam of light is respectively connected with a pumping signal input end of a remote pump module (47) after passing through a transmission optical fiber;
the remote pump module comprises a second circulator (10), a second wavelength division multiplexer (11), a first erbium-doped optical fiber (12), a third circulator (13), a second optical fiber coupler (33), a third wavelength division multiplexer (34) and a second erbium-doped optical fiber (35); the a port of the second circulator (10) is connected with the second end of the previous optical fiber to be tested, the b port of the second circulator (10) is connected with the a port of the second wavelength division multiplexer (11), the c port of the second wavelength division multiplexer (11) is connected with the a port of the third circulator (13) through the first erbium-doped optical fiber (12), the c port of the third wavelength division multiplexer (34) is connected with the c port of the third circulator (13) through the second erbium-doped optical fiber (35), and the b port of the third circulator (13) is used as the output end of the remote pump module (47) to be tested; the input end of the second optical fiber coupler (33) is used as a pumping signal input end and is used for dividing a pumping signal output by the multi-channel adjustable optical attenuator (31) into two beams, one beam is output to the b port of the second wavelength division multiplexer (11), pulse light output in the previous optical fiber to be tested is amplified through the first erbium-doped optical fiber (12), the other beam is output to the b port of the third wavelength division multiplexer (34), and a backward Rayleigh scattering signal entering the second erbium-doped optical fiber (35) is amplified;
the c port of the first circulator (7) is connected with a first optical fiber coupler (27) after passing through an optical filter (26), the first optical fiber coupler (27) is used for combining local light and a backward Rayleigh scattering signal output from the c port of the first circulator (7) and then sending the combined light to the detector (28), and the computer (29) is connected with the detector (28) and is used for calculating and obtaining vibration information in each optical fiber to be detected according to detection signals of the detector (28).
2. The single light source pumped dynamic remote pump distributed optical fiber vibration monitoring device according to claim 1, wherein the pulse optical amplifier (15) comprises a fourth wavelength division multiplexer (5) and a third erbium-doped optical fiber (6), an a port of the fourth wavelength division multiplexer (5) is connected with the acousto-optic modulator (3), a c port is connected with one end of the third erbium-doped optical fiber (6), a b port is connected with a third beam of laser light emitted by the second laser (30), and the other end of the third erbium-doped optical fiber (6) is connected with an a end of the first circulator (7).
3. The single light source pumped dynamic remote pump distributed optical fiber vibration monitoring device according to claim 1, wherein the first laser (1) is a narrow linewidth laser with a wavelength of 1550nm and the second laser (30) has a wavelength of 1480nm.
4. The single light source pumped dynamic remote pump distributed optical fiber vibration monitoring device of claim 1, wherein the length of the transmission optical fiber connected to each remote pump module is equal to the sum of the lengths of the optical fibers to be measured at the proximal end of the corresponding remote pump module.
5. The single-light-source-pumped dynamic remote pump distributed optical fiber vibration monitoring device according to claim 1, wherein the number of the optical fibers to be tested is four, namely a first optical fiber to be tested (9), a second optical fiber to be tested (14), a third optical fiber to be tested (19) and a fourth optical fiber to be tested (24), and the remote pump modules comprise three, namely a first remote pump module (47), a second remote pump module (48) and a third remote pump module (49); the first optical fiber to be tested (9), the first remote pump module (47), the second optical fiber to be tested (14), the second remote pump module (48), the third optical fiber to be tested (19), the third remote pump module (49) and the fourth optical fiber to be tested (24) are connected in sequence;
the multi-channel adjustable optical attenuator (31) divides pump light signals into three bundles, one bundle is connected with a first remote pump module (47) through the first transmission optical fiber (32), the other bundle is connected with a second remote pump module (48) through the second transmission optical fiber (36), the third bundle is connected with a third remote pump module (49) through the third transmission optical fiber (41), the length of the first transmission optical fiber (32) is equal to the sum of the first optical fiber (9) to be measured and the second optical fiber (14) to be measured, the length of the second transmission optical fiber (36) is equal to the sum of the first optical fiber (9) to be measured, the second optical fiber (14) to be measured and the third optical fiber (19) to be measured.
6. The single light source pumped dynamic remote pump distributed optical fiber vibration monitoring device according to claim 1, wherein the first optical splitter (2) is an optical fiber coupler with a split ratio of 90:10, 90% of the optical fiber coupler is used as probe light, 10% of the optical fiber coupler is used as local light, and the second optical fiber coupler (33) is an optical fiber coupler with a split ratio of 50:50.
7. A single light source pumped dynamic remote pump distributed optical fiber vibration monitoring device according to claim 1, characterized in that the control terminal of the multi-channel variable optical attenuator (31) is connected to the computer (29), which is further adapted to control the power of the respective output terminal of the multi-channel variable optical attenuator (31) for controlling the pump signal input in the respective remote pump module (47).
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| JPH08247790A (en) * | 1995-03-10 | 1996-09-27 | Sefuto Kenkyusho:Kk | Position detection apparatus |
| CN204177478U (en) * | 2014-09-01 | 2015-02-25 | 中国石油天然气股份有限公司 | A kind of fiber-optic vibration checkout equipment amplified based on the distant pump of different fibre |
| CN109632076A (en) * | 2019-01-31 | 2019-04-16 | 电子科技大学 | The amplification system and method for long-distance optical fiber distribution sound wave sensing |
| CN113810110A (en) * | 2021-11-19 | 2021-12-17 | 北京邮电大学 | Transmission system based on hybrid fiber amplifier |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20020159138A1 (en) * | 2001-04-30 | 2002-10-31 | Meiyu Zou | Access device for pump source in cascade erbium-doped fiber amplification |
| WO2019039590A1 (en) * | 2017-08-25 | 2019-02-28 | 日本電信電話株式会社 | Optical amplification repeating system, and optical amplifier |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08247790A (en) * | 1995-03-10 | 1996-09-27 | Sefuto Kenkyusho:Kk | Position detection apparatus |
| CN204177478U (en) * | 2014-09-01 | 2015-02-25 | 中国石油天然气股份有限公司 | A kind of fiber-optic vibration checkout equipment amplified based on the distant pump of different fibre |
| CN109632076A (en) * | 2019-01-31 | 2019-04-16 | 电子科技大学 | The amplification system and method for long-distance optical fiber distribution sound wave sensing |
| CN113810110A (en) * | 2021-11-19 | 2021-12-17 | 北京邮电大学 | Transmission system based on hybrid fiber amplifier |
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