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Long-distance optical fiber Bragg grating sensing method and device based on self-heterodyne detection

A fiber Bragg and grating sensing technology, applied in the field of sensing, can solve the problems of limiting the application range of sensing devices, increasing back Rayleigh scattering, and increasing complexity, and achieves simple structure, increased sensing distance, and control convenient effect

Inactive Publication Date: 2012-08-01
NANJING UNIV
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Problems solved by technology

Moreover, the increase of input optical power will also lead to the increase of back Rayleigh scattering, affecting the signal-to-noise ratio
In order to solve these problems, the sensing device needs to add additional devices, which further increases the complexity
This will limit the practical application range of the sensing device

Method used

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  • Long-distance optical fiber Bragg grating sensing method and device based on self-heterodyne detection
  • Long-distance optical fiber Bragg grating sensing method and device based on self-heterodyne detection

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Embodiment Construction

[0009] Such as figure 1 As shown, a long-distance fiber Bragg grating sensing device based on self-heterodyne detection technology includes a narrow linewidth wavelength tunable laser 1, a three-port 3dB optical coupler 2, a polarization scrambler 3, an optical pulse modulation module 4, Optical isolator 5, two long-distance optical fibers of the same (or similar) length 6 and 9, optical circulator 7, sensing fiber Bragg grating 8, frequency shifting module 10, four-port 3dB coupler 11, balanced photodetector 12 , Signal acquisition analysis and control module 13. The output port of the wavelength tunable laser 1 is connected to the port of the single-port end of the three-port 3dB optical coupler 2, one port of the two-port end of the three-port 3dB optical coupler 2 is connected to the input port of the scrambler 3, and the Another port of the dual-port end is connected to the input port of the optical pulse modulation module 4; the output port of the optical pulse modulati...

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Abstract

The invention relates to a long-distance optical fiber Bragg grating sensing method and device based on self-heterodyne detection. A single frequency light beam sent from a wavelength adjustable narrow line width laser is split into two parts of light beam with the same intensity after passing through a triport optical fiber coupler, one part of the light beam passes through a scrambler and is used as an intrinsic light, and the other part of the light beam passes through a light pulse modulation module and is modulated into a pulse detection light; and the detection pulse light passes through an optical isolator, enters a segment of a long-distance transmission optical fiber, and then enters a sensing optical fiber grating array through a far-end light circulator; and the signal reflected from the optical fiber grating shifts frequency of the returned reflection sensing signal through a frequency shift module and then enters a four-port optical coupler together with the intrinsic light, and the generated coherent light signal enters a balance photoelectric detector through the other two ports of the optical coupler and is converted to an electrical signal. The electrical signal received and converted by a signal collection analysis and control module is collected and analyzed to obtain the time domain track of the sensing signal, and the peak power is the power of the coherent signal.

Description

technical field [0001] The invention belongs to the field of sensing technology, and relates to a method for improving detection sensitivity based on self-heterodyne detection technology combined with a wavelength-tunable laser and a long-distance sensing method for eliminating back Rayleigh scattering structures, that is, a long-distance fiber Bragg grating Sensing method and device implementing the method. Background technique [0002] Fiber Bragg Grating (FBG) has the advantages of high sensitivity, anti-electromagnetic interference, simple structure and high resolution, and its application in the field of sensing has attracted great attention. In practical applications, long-distance fiber grating sensing devices can be widely used in various fields such as oil pipelines and substations. Due to the influence of factors such as Rayleigh scattering and loss of optical fiber, when a broadband light source is used for research on fiber grating sensing devices, the farthest ...

Claims

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Application Information

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IPC IPC(8): G01D5/353G01D5/38
Inventor 许国良蔡江江赵晓东
Owner NANJING UNIV
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