CN102589459A - Fully-distributed optical fiber sensor in combination of optical fiber Raman frequency shifter and Raman amplifier - Google Patents

Abstract

The invention discloses a fully-distributed optical fiber sensor in combination of an optical fiber Raman frequency shifter and a Raman amplifier. After shifting frequency for 13.2 THz by the optical fiber Raman frequency shifter, an optical fiber pulsing laser produces a broad spectrum Raman laser with a 1660nm wave band, wherein the broad spectrum Raman laser is served as the broad spectrum light source of the fully-distributed optical fiber sensor for performing the incidence of a sensing fiber; the deformation and the breaking of the optical fiber can be detected based on the reverse Rayleigh scattering strength ratio of the sensing fiber; the 1550nm wave band produced in the sensing fiber undergoes reverse anti-Stokes Raman scattering and is amplified by the optical fiber Raman amplifier; the temperature information at each section of the optical fiber can be obtained by deducting the influence produced by straining according to the strength ratio of the anti-Stokes Raman scattered light to the Rayleigh scattered light; the inspection on the training and the temperature is out of cross effect; the detection point on the sensing fiber can be located by using an optical time domain reflection technology. The fully-distributed optical fiber sensor is applied to the monitoring of petrochemical pipes, tunnels and large-scale civil engineering within ultra-long range of 100 kilometers, as well as disaster prediction monitoring.

Description

Fully Distributed Optical Fiber Sensor Fused with Fiber Raman Frequency Shifter and Raman Amplifier

technical field

The invention relates to the field of optical fiber sensors, in particular to a distributed optical fiber Rayleigh and Raman scattering photon strain and temperature sensor.

Background technique

The optical fiber sensor network developed in recent years can realize the safety and health monitoring and disaster forecasting and monitoring of large-scale civil engineering, electric power engineering, petrochemical industry, traffic bridges, tunnels, subway stations, dams, embankments and mining projects. There are two types of optical fiber sensors: one is a quasi-distributed optical fiber sensor network composed of point sensors such as fiber grating (FBG) and fiber optic method white (F-P) "hanging" (laying) on the optical fiber and using optical time domain technology , the main problem of the quasi-distributed optical fiber sensor network is that the optical fiber between point sensors is only the transmission medium, so there is a detection "blind zone"; another type uses the intrinsic characteristics of optical fiber, optical fiber Rayleigh, Raman and Brillouin Scattering effect, using a fully distributed optical fiber sensor network composed of optical time domain (OTDR) technology, to measure strain and temperature. The optical fiber in the fully distributed optical fiber sensor network is both the transmission medium and the sensing medium, and there is no detection blind area.

Zhang Zaixuan's "Fully Distributed Optical Fiber Rayleigh and Raman Scattering Photon Strain and Temperature Sensor" (Chinese Invention Patent, Patent No.: 200910099463.7, authorized on September 29, 2010) provides a simple structure, good signal-to-noise ratio, Distributed optical fiber Rayleigh and Raman scattering photon strain and temperature sensors with good reliability are suitable for the detection range of medium and short-range 0-15km fully distributed optical fiber sensor networks. However, it can no longer fully meet the urgent needs of the safety and health monitoring of oil pipelines and transmission power cables in recent years, and the long-range and ultra-long-distance fully distributed optical fiber Rayleigh, Raman and Brillouin scattering strain and temperature sensor networks.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the prior art and provide a fully distributed optical fiber sensor that integrates an optical fiber Raman frequency shifter and a Raman amplifier. 100km distributed optical fiber Rayleigh and Raman scattering photon strain and temperature sensors.

The purpose of the present invention is achieved through the following technical solutions: a fully distributed optical fiber sensor that fuses an optical fiber Raman frequency shifter and a Raman amplifier, including a fiber optic pulse laser, and the optical fiber Raman frequency shifter consists of a single-mode fiber and a 1660nm Composition of laser sheet, optical fiber wavelength division multiplexer, optical fiber coupler, optical fiber Raman laser, sensing optical fiber, optical fiber narrowband reflection filter, photoelectric receiving module, digital signal processor and industrial computer. The fiber pulse laser emits laser light and enters the fiber Raman frequency shifter, which is frequency-shifted from 13.2THz to 1660nm band. As a wide-spectrum light source, the laser enters the fiber wavelength division multiplexer. The fiber wavelength division multiplexer has four ports, and its input port It is connected to the output port of the fiber Raman frequency shifter, and the COM output port is connected to the sensing fiber through a fiber narrowband reflection filter and a fiber coupler; the fiber Raman laser, the fiber coupler and the sensing fiber form a C-band fiber Raman amplifier , the 1660nm band wide-spectrum Rayleigh backscattered light generated in the sensing fiber is connected to an input port of the photoelectric receiving module through a 1450nm fiber narrowband reflection filter and an output port of the fiber wavelength division multiplexer, and is converted by photoelectricity After amplification, it is input to a port of the digital signal processor; generated in the sensing fiber, the 1550nm band wide-spectrum reverse anti-Stokes Raman scattered light amplified by the Raman amplifier passes through the 1450nm fiber narrowband reflection filter and the fiber optic The other output port of the wavelength division multiplexer is connected with the other input port of the photoelectric receiving module, and input to the other port of the digital signal processor after photoelectric conversion and amplification, and the digital signal processor is connected with the industrial computer. After demodulation by the digital signal processor and the industrial computer, the deformation and fracture of the optical fiber are detected by using the principle that the Rayleigh scattering intensity of the optical fiber is modulated by the strain of the optical fiber. Based on the principle that the optical fiber anti-Stokes Raman light intensity is modulated by the temperature of the optical fiber, the The ratio of optical fiber anti-Stokes Raman light intensity to optical fiber Rayleigh scattered light intensity detects the temperature of the optical fiber, and the influence of strain is deducted, and there is no cross effect between them.

The ultra-long-distance fully distributed optical fiber sensor fused with the optical fiber Raman frequency shifter is characterized in that the central wavelength of the high-power pulse laser is 1550nm, the spectral width is 0.1nm, the laser pulse width is 10-30ns adjustable, and the peak power It is adjustable from 1-1kW, and the repetition frequency is adjustable from 500Hz-800Hz.

The ultra-long-distance fully distributed optical fiber sensor of the fusion optical fiber Raman frequency shifter is characterized in that it adopts an optical fiber Raman frequency shifter, which is composed of a 1km single-mode optical fiber and a 1660nm bandpass filter, and the filter center wavelength It is 1660nm, the spectral bandwidth is 28nm, the transmittance is 98%, and the isolation to 1550nm laser is >45dB.

The fiber Raman frequency shifter shifts the frequency of the fiber laser in the 1550nm band by 13.2THz to the 1660nm band, and broadens the spectral bandwidth of the laser, as a wide-spectrum light source for fully distributed fiber optic sensors.

The fully distributed optical fiber sensor of the described fusion optical fiber Raman frequency shifter, Raman amplifier is characterized in that optical fiber wavelength division multiplexer, it has 1660nm laser input port, COM output port, 1550nm output port and 1660nm output port etc. four ports.

The fully distributed optical fiber sensor of the fusion optical fiber Raman frequency shifter and Raman amplifier is characterized in that one end of the optical fiber coupler is connected with the optical fiber Raman laser, and the other two ends are respectively connected with the sensing optical fiber and the optical fiber narrowband reflection filter connected to the device.

The fusion optical fiber Raman frequency shifter and the fully distributed optical fiber sensor of the Raman amplifier are characterized in that the central wavelength of the optical fiber Raman laser is 1450.0nm, the spectral bandwidth is 0.1nm, and the output power is adjustable from 100-1200mW. A coupler, a fiber Raman laser and a sensing fiber constitute a C-band fiber Raman amplifier.

The fully distributed optical fiber sensor of the fusion optical fiber Raman frequency shifter and Raman amplifier is characterized in that the sensing optical fiber adopts G652 single-mode optical fiber or LEAF optical fiber for 100km communication, and carbon-coated single-mode optical fiber is used for special occasions.

Carbon-coated single-mode fiber is a special fiber that deposits a layer of amorphous carbon on the surface of the bare fiber during the drawing process. This carbon sealing coating technology solves the long-term reliability problems such as the decrease of mechanical strength of the optical fiber due to static fatigue and the increase of transmission loss due to the diffusion of hydrogen into the quartz glass body. This carbon-coated optical fiber can work reliably for a long time in harsh and harsh environments. Carbon-coated optical fiber is to add a layer of dense carbon film with a thickness of 35 to 70nm on the cladding surface of the optical fiber, and then coat a layer of UV-curable organic coating. The dense carbon film can greatly enhance the protection of the bare optical fiber in harsh environments. To ensure its durability, the sensing optical fiber is laid on site. The optical fiber has no electricity, anti-electromagnetic interference, radiation resistance, corrosion resistance, and good reliability. The optical fiber is both a transmission medium and a sensing medium.

The fully distributed optical fiber sensor of the fusion optical fiber Raman frequency shifter and Raman amplifier is characterized in that the central wavelength of the optical fiber narrowband reflection filter is 1450.0nm, the spectral bandwidth is 0.5nm, and the reflectivity is 99%.

The fully distributed optical fiber sensor of the fusion fiber Raman frequency shifter and Raman amplifier is characterized in that the photoelectric receiving module adopts two low-noise InGaAs photoelectric avalanche diodes and low-noise broadband preamplifier integrated chip MAX4107 and three-stage Composition of the main amplifier.

Working principle of fiber Raman frequency shifter :

When the incident laser ν ₀ interacts nonlinearly with the fiber molecules, a phonon is emitted, which is called Stokes Raman scattering photon, and a phonon is absorbed, which is called anti-Stokes Raman scattering photon Δν. The phonon frequency is 13.2THz, and the incident laser ν ₀ produces a frequency shift:

ν= _ν0 ±Δν; (1)

It is called fiber optic Raman frequency shifter, which can be made into fiber optic Raman frequency shifter. If the incident laser light exceeds a certain threshold, the Stokes wave ν=ν ₀ -Δν in the fiber increases rapidly in the fiber medium, and most of the power of the pump light can be converted into Stokes light. The Raman scattering phenomenon becomes the working principle of the fiber optic Raman frequency shifter. Fiber Raman frequency shifter consists of 1km single-mode fiber, which can combine 1550nm fiber pulse laser and 1660nm bandpass filter to convert 1550nm fiber pulse laser into 1660nm band wide-spectrum Raman laser.

Working Principle of Distributed Fiber Raman Amplifier

The switching gain of the amplifier is:

; (2)

是放大器的泵浦光输入功率，是拉曼增益系数

是光纤的有效截面，

 为光纤的有效作用长度 （考虑了光纤对泵浦的吸收损耗），其表达式如下： in,

is the pump light input power of the amplifier, is the Raman gain coefficient

is the effective cross-section of the fiber,

is the effective length of the optical fiber (considering the absorption loss of the optical fiber to the pump), and its expression is as follows:

  ；                    （3）

; (3)

For fiber Raman amplifiers, only when the pump power exceeds a certain threshold, it is possible to generate stimulated Raman amplification to the signal. The Stokes wave in the fiber ν=ν ₀ -Δν increases rapidly in the fiber medium, Most of the power of the pump light can be converted into Stokes light, which has the effect of Raman amplification. The gain can suppress the transmission loss of the fiber and improve the working distance of the fully distributed fiber strain and temperature sensors. This stimulated pull The Mann scattering phenomenon is used to increase the working distance of the fully distributed optical fiber sensor. Usually, the gain of the optical fiber Raman amplifier can reach 25dB, which is equivalent to increasing the working distance of the sensor by nearly 60km.

The principle of distributed optical fiber Rayleigh scattering photon sensor to measure deformation :

The fiber pulse laser emits laser pulses and injects them into the sensing fiber through the integrated fiber wavelength division multiplexer. The interaction between the laser and the fiber molecules produces Rayleigh scattered light with the same frequency as the incident photon, and the Rayleigh scattered light is transmitted and stored in the fiber. The loss is exponentially attenuated with the length of the fiber, and the scattered light intensity at the back end is expressed by the following formula:

      ；                           （4）

;(4)

为入射光波长处的光纤传输损耗。 In the above formula, is the light intensity incident on the fiber, L is the length of the fiber, I is the light intensity of the back Rayleigh scattered light at the fiber length L ,

is the fiber transmission loss at the incident light wavelength.

，则总损耗

，局域处的光强有一个跌落，光强由

减少为

，形变造成的附加损耗通过光强的改变进行测量： Since the optical fiber lays the sensing optical fiber on the detection site, when the site environment is deformed or cracked, the optical fiber laid on the site will be bent, and the optical fiber will generate local loss, forming additional loss of the optical fiber.

, the total loss

, the light intensity at the local area has a drop, and the light intensity is determined by

reduced to

, the additional loss due to deformation is measured by the change in light intensity:

       ；                                 （5）

; (5)

The relationship between deformation or crack size and fiber loss is calculated by using a simulation model and measured by a simulation test in a laboratory. the

The principle of temperature measurement by distributed optical fiber Raman scattering photon sensor :

When the incident laser light interacts nonlinearly with the fiber molecules, a phonon is released, called Stokes Raman scattering photons, and a phonon is absorbed, called anti-Stokes Raman scattering photons, the phonon frequency of fiber molecules It is 13.2THz. The thermal distribution of the number of particles on the molecular energy level of the optical fiber obeys Boltzmann's law, and the anti-Stokes back Raman scattering light intensity in the optical fiber is:

   ；           （6）

;(6)

It is modulated by the fiber temperature, the temperature modulation function R _a :

     ；               （7）

;(7)

h is the Planck constant, Δν is the phonon frequency of a fiber molecule, which is 13.2THz, k is the Boltzmann constant, and T is the Kelvin absolute temperature.

In the present invention, the optical fiber Rayleigh channel is used as a reference signal, and the temperature is detected by the ratio of anti-Stokes Raman scattered light and Ray scattered light intensity:

 ；           （8）

; (8)

The temperature information of each segment of the fiber is obtained from the ratio of anti-Stokes Raman scattered light and Ray scattered light to light intensity of the optical fiber Raman optical time domain reflectance (OTDR) curve at the fiber detection point, and the influence of strain is deducted.

The beneficial effect of the present invention is that: the fully distributed optical fiber sensor fusion optical fiber Raman frequency shifter of the present invention fusion fiber Raman frequency shifter and Raman amplifier can move the laser light to the 1660nm wave band and have a 28nm wide spectrum, suppressing Coherent noise and move the anti-Stokes Raman light with temperature information in the sensing fiber to the low-loss band of 1550nm fiber, which improves the signal-to-noise ratio of the sensor system; integrates the C-band fiber Raman amplifier to amplify The anti-Stokes Raman light in the 1550nm band has a gain of nearly 25dB, which is equivalent to increasing the measurement length by 60km. While measuring the on-site temperature, it can measure the on-site deformation, cracks and temperature without intersecting each other. The sensing optical fiber laid on the disaster prevention site is insulated, uncharged, anti-electromagnetic interference, radiation-resistant, corrosion-resistant, and intrinsically safe. The optical fiber is both a transmission medium and a sensing medium, and it is an intrinsic type of sensor. Sensing optical fiber, and has a long life of more than 50 years, the invention is suitable for ultra-long-distance 100km fully distributed optical fiber strain and temperature sensing network.

Description of drawings

Fig. 1 is the schematic diagram of the fully distributed optical fiber sensor of fusion optical fiber Raman frequency shifter and Raman amplifier;

In the figure, fiber pulse laser 11, single-mode fiber 12, 1660nm laser sheet 13, fiber wavelength division multiplexer 14, fiber coupler 15, fiber Raman laser 16, sensing fiber 17, fiber narrowband reflective filter 18, A photoelectric receiving module 19 , a digital signal processor 20 , and an industrial computer 21 .

Detailed ways

The purpose and effects of the present invention will become more apparent by describing the present invention in detail below with reference to the accompanying drawings.

Referring to Fig. 1, the fully distributed optical fiber sensor of the present invention fusion optical fiber Raman frequency shifter and Raman amplifier comprises: optical fiber pulse laser 11, single-mode optical fiber 12, 1660nm laser chip 13, optical fiber wavelength division multiplexer 14, optical fiber coupling device 15, optical fiber Raman laser 16, sensing optical fiber 17, optical fiber narrowband reflection filter 18, photoelectric receiving module 19, digital signal processor 20 and industrial computer 21. The single-mode fiber 12 and the 1660nm laser sheet 13 form a fiber Raman frequency shifter; the fiber pulse laser 11 emits laser light and enters the fiber Raman frequency shifter, after frequency shifting 13.2THz to the 1660nm band, the laser light enters the fiber wavelength division multiplexer as a wide-spectrum light source. With the device 14, the optical fiber wavelength division multiplexer 14 has four ports, its input port is connected with the output port of the optical fiber Raman frequency shifter, and the COM output port is connected with the sensor through the optical fiber narrowband reflection filter 18 and the optical fiber coupler 15 The optical fiber 17 is connected; the optical fiber Raman laser 16, the optical fiber coupler 15 and the sensing optical fiber 17 form a C-band optical fiber Raman amplifier, and the 1660nm band wide spectrum reverse Rayleigh scattered light generated in the sensing optical fiber 17 is reflected by the 1450nm optical fiber narrowband An output port of the optical filter 18 and the optical fiber wavelength division multiplexer 14 is connected with an input port of the photoelectric receiving module 19, and is input to a port of the digital signal processor 20 after being amplified by photoelectric conversion; , the 1550nm band broad-spectrum reverse anti-Stokes Raman scattered light amplified by the Raman amplifier passes through the 1450nm optical fiber narrowband reflective filter 18 and another output port of the optical fiber wavelength division multiplexer 14 and the photoelectric receiving module 19 The other input port is connected to the other port of the digital signal processor 20 after photoelectric conversion and amplification, and the digital signal processor 20 is connected to the industrial computer 21 .

The central wavelength of the fiber pulse laser 11 is 1550nm, the spectral width is 0.2nm, the laser pulse width is 10ns, the peak power is adjustable at 100W, and the repetition frequency is adjustable at 500Hz-800KHz.

Described optical fiber Raman frequency shifter, it is made up of 1km single-mode optical fiber 12 and 1660nm laser plate 13, and optical filter center wavelength is 1660nm, spectral bandwidth 28nm, transmittance 98%, to the isolation degree of 1550nm laser > 45dB .

Described optical fiber wavelength division multiplexer 14, it has four ports such as 1660nm laser input port, COM output port, 1550nm output port and 1660nm output port.

One end of the fiber coupler 15 is connected to a fiber Raman laser 16 , and the other two ends are connected to a sensing fiber 17 and a fiber narrowband reflection filter 18 respectively.

The central wavelength of the fiber Raman laser 16 is 1450.0nm, the spectral bandwidth is 0.1nm, and the output power is adjustable from 100-1200mW. The fiber coupler 15, the fiber Raman laser 16 and the sensing fiber 17 form a C-band fiber Raman amplifier.

The sensing optical fiber 17 adopts G652 single-mode optical fiber or LEAF optical fiber for 100km communication, and carbon-coated single-mode optical fiber is used for special occasions.

The optical fiber narrow-band reflective filter 18 has a center wavelength of 1450.0 nm, a spectral bandwidth of 0.5 nm, and a reflectivity of 99%.

The photoelectric receiving module 19 is composed of two low-noise InGaAs photoelectric avalanche diodes, a low-noise broadband preamplifier integrated chip MAX4107 and a three-stage main amplifier.

Described digital signal processor 20 adopts the ATS 9642 type 16 two-channel of Alazar Tech.

High-speed broadband signal acquisition and processing card.

The working process of the present invention is as follows: when working, the optical pulse laser sends laser pulses into the fiber Raman frequency shifter, and the fiber Raman frequency shifter shifts the frequency of the fiber pulse laser in the 1550nm band by 13.2THz to the 1660nm band as a fully distributed optical fiber Broad-spectrum light source for the sensor. Broad-spectrum laser pulses enter the sensing fiber through the fiber optic wavelength division multiplexer, fiber optic narrow-band reflection filter and fiber coupler, and the 1660nm band reverse Rayleigh scattering generated in the sensing fiber passes through the wavelength division multiplexer and photoelectric receiving The module converts the optical signal into an analog electrical signal and amplifies it, and obtains the strain information from the intensity ratio of Rayleigh scattered light; a C-band fiber Raman amplifier is composed of a fiber Raman laser, a fiber coupler and a sensing fiber, and the sensing fiber The anti-Stokes Raman scattering generated in the 1550nm band is amplified by the optical fiber Raman amplifier, and then passed through the wavelength division multiplexer. The amplified anti-Stokes Raman scattering light with temperature information passes through the photoelectric receiving module. The intensity ratio of anti-Stokes Raman scattered light to Rayleigh scattered light, deducting the influence of strain to obtain the temperature information of each section of the optical fiber, there is no cross effect in the detection of strain and temperature, using optical time domain reflection to detect The detection point positioning (fiber radar positioning). Through the demodulation of the digital signal processor and the strain and temperature demodulation software, the strain and temperature measurement are calibrated, and the strain and temperature changes at each point on the 100km sensing fiber are obtained within 60 seconds, and the temperature measurement accuracy is ±2oC, which is controlled by the computer. The communication interface and communication protocol are used for remote network transmission. When the detection point on the sensing fiber reaches the set strain or temperature alarm set value, an alarm signal is sent to the alarm controller.

Claims (8)

1. A fully distributed optical fiber sensor that combines a fiber Raman frequency shifter and a Raman amplifier, characterized in that it includes: a fiber pulse laser (11), a single-mode fiber (12), and a 1660nm laser chip (13) , optical fiber wavelength division multiplexer (14), optical fiber coupler (15), optical fiber Raman laser (16), sensing optical fiber (17), optical fiber narrowband reflective filter (18), photoelectric receiving module (19), Digital signal processor (20) and industrial computer (21), etc.; among them, single-mode fiber (12) and 1660nm laser sheet (13) constitute fiber Raman frequency shifter, fiber Raman laser (16), fiber coupler ( 15) Combined with the sensing fiber (17) to form a C-band fiber Raman amplifier; the fiber pulse laser (11) emits laser light and enters the fiber Raman frequency shifter, and after frequency shifting from 13.2THz to 1660nm band, the laser light enters the fiber wave as a wide-spectrum light source The division multiplexer (14), the optical fiber wavelength division multiplexer (14) has four ports, its 1660nm laser input port is connected with the output port of the optical fiber Raman frequency shifter, and the COM output port passes through the optical fiber narrowband reflection filter ( 18) and the fiber coupler (15) are connected with the sensing fiber (17); the 1660nm band wide-spectrum Rayleigh backscattered light generated in the sensing fiber (17) passes through the fiber narrowband reflection filter (18) and the fiber The 1660nm output port of the wavelength division multiplexer (14) is connected to an input port of the photoelectric receiving module (19), and is input to a port of the digital signal processor (20) after being amplified by photoelectric conversion; in the sensing fiber (17) The 1550nm band wide-spectrum reverse anti-Stokes Raman scattered light amplified by the Raman amplifier passes through the 1550nm output port of the optical fiber narrowband reflection filter (18) and the optical fiber wavelength division multiplexer (14) and the photoelectric receiver The other input port of the module (19) is connected to the other port of the digital signal processor (20) after being amplified by photoelectric conversion, and the digital signal processor (20) is connected to the industrial computer (21). 2. The fully distributed optical fiber sensor fused with optical fiber Raman frequency shifter and Raman amplifier according to claim 1, characterized in that, the central wavelength of the optical fiber pulse laser (11) is 1550nm, and the spectral width is 0.2nm , The laser pulse width is adjustable from 10-30ns, the peak power is adjustable from 100W, and the repetition frequency is adjustable from 500Hz-800KHz. 3. The fully distributed optical fiber sensor that fuses a fiber Raman frequency shifter and a Raman amplifier according to claim 1, wherein the fiber Raman frequency shifter consists of a 1km single-mode fiber (12) and a 1660nm laser (13), the central wavelength of the filter is 1660nm, the spectral bandwidth is 28nm, the transmittance is 98%, and the isolation to 1550nm laser is >45dB. 4. The fully distributed optical fiber sensor fused with optical fiber Raman frequency shifter and Raman amplifier according to claim 1, characterized in that the optical fiber wavelength division multiplexer (14) has a 1660nm laser input port, Four ports such as COM output port, 1550nm output port and 1660nm output port. 5. The fully distributed optical fiber sensor fused with fiber Raman frequency shifter and Raman amplifier according to claim 1, characterized in that, the central wavelength of the fiber Raman laser (16) is 1450.0nm, and the spectral bandwidth is 0.1 nm, the output power is adjustable from 100-1200mW. 6. The fully distributed optical fiber sensor fused with optical fiber Raman frequency shifter and Raman amplifier according to claim 1, characterized in that, the sensing optical fiber (17) adopts G652 single-mode optical fiber and LEAF optical fiber for 100km communication or carbon-coated single-mode fiber. 7. The fully distributed optical fiber sensor fused with optical fiber Raman frequency shifter and Raman amplifier according to claim 1, characterized in that, the central wavelength of the optical fiber narrowband reflective filter (18) is 1450.0nm, and the spectrum Bandwidth 0.5nm, reflectivity 99%. 8. The fusion optical fiber Raman frequency shifter according to claim 1, the fully distributed optical fiber sensor of the Raman amplifier, characterized in that, the photoelectric receiving module (19) adopts two low-noise InGaAs photoelectric avalanche diodes and The low-noise broadband preamplifier is composed of integrated chip MAX4107 and three-stage main amplifier.

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