Optical cable wiring structure based on POTDR system for measuring disturbance

A wiring structure and optical cable technology, applied in the field of polarized light time domain reflection detection, can solve the problem of no optical cable birefringence sensitivity optical cable wiring method, etc., and achieve the effects of improving sensitivity, large laying area, and improving accuracy

Active Publication Date: 2019-09-13
NANJING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The change of the polarization state of the light wave in the optical cable is mainly caused by the change of the birefringence, and so far, the optical cable wiring method basically adopts the straight wiring, and there is almost no research on the optical cable wiring method to improve the birefringence sensitivity of the optical cable.

Method used

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  • Optical cable wiring structure based on POTDR system for measuring disturbance
  • Optical cable wiring structure based on POTDR system for measuring disturbance
  • Optical cable wiring structure based on POTDR system for measuring disturbance

Examples

Experimental program
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Effect test

Embodiment 1

[0044] figure 1 (a) shows the S-shaped wiring structure. Such as figure 1As shown in (a), the optical cable is arranged in an "S" shape on a bottom line. According to the analysis of the working principle, if the phase difference caused by the bending birefringence δ≥0.02π, the downward bending radius R≤68mm caused by stepping is required. However, due to the limitation of the height of the base, it can be obtained that the distance between the contact end of the optical cable and the ground and the base is l, and the length of the optical cable affected by the bending is about The actual phase difference change is less than 0.02π. In order to achieve the required phase difference, it is necessary to further reduce the radius of the downward bend. According to the calculation, the required downward bending radius is R=30mm, and the length of the affected optical cable at this time is 8.71πmm. At this time, the force required to make the optical cable bend like this is ...

Embodiment 2

[0047] figure 1 (b) shows the ring wiring structure. Such as figure 1 As shown in (b), the optical cable is laid on the base line in a ring shape. In this wiring structure, the induced birefringence is still mainly caused by bending. The layout parameters are approximately equal to those in the S"-shaped wiring scheme, but the difference is that due to the circular layout, under the same external event, the length of the affected optical cable becomes twice that of Embodiment 1. Due to more The optical cable disperses the force of stepping on it, so the pressure per unit length of the optical cable will be less than that of the "S" shape wiring scheme. But because the length of the affected optical cable has doubled, the overall sensitivity is better than that of embodiment one, but for the same monitoring area, the required cable length will double.

[0048] In this embodiment, we bend and fix the optical cable on the bottom line according to the loop wiring method, and t...

Embodiment 3

[0050] figure 1 (c) shows the overlapping ring wiring structure. Such as figure 1 As shown in (c), in the overlapping ring wiring structure, the overlapping ring layout is similar to the ring layout, but on the basis of it, the following circular arc line is placed on the previous circular arc line, so there are more bending points, The higher degree of bending can significantly improve the sensitivity of the system on the second wiring scheme.

[0051] In this embodiment, we bend and fix the optical cable on the bottom line according to the loop wiring method, and then place the optical cable on the figure 2 Between the coupler and the polarizer, the optical fiber signal is collected in different places of the optical cable by taking the walking of a normal person as an example. Then the collected signal is processed with MATLAB software, in which Figure 5 is the differential curve result of the polarization signal obtained by applying pressure at two different position...

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Abstract

The invention discloses an optical cable wiring structure based on a POTDR system for measuring disturbance. The optical cable wiring structure comprises a pulse laser, a polarizer, a coupler, an analyzer, a detector, a signal collection module, a signal processing module, an optical cable and a bottom line; the optical cable is horizontally bent and arranged on the bottom line, and the bottom line is used for generating a bottom height for the optical cable, so that the optical cable is bent in a vertical direction when subjected to a vertical pressure. The optical cable cable is arranged inan ''S'' shape on the bottom line; or the optical cable is coiled into a plurality of circles to be arranged on the bottom line, the circle centers of the circles are distributed on the bottom line, and the adjacent circle centers have the same distance, and the circles have the same size and are not overlapped with each other; or the circles have the same size and are partially overlapped with each other. Compared with straight wiring, the optical cable wiring structure disclosed by the invention not only has a larger effective pavement area, but also can bend the optical cable to a greater extent under the same stress variation, thereby greatly improving the sensitivity of the POTDR system and improving the accuracy of intrusion detection.

Description

technical field [0001] The invention relates to the field of polarized light time-domain reflection detection, in particular to an optical cable wiring structure for measuring disturbance based on a POTDR system. Background technique [0002] The Polarization Optical Time-Domain Reflectometer (POTDR) can realize the distributed measurement of the disturbance to the optical fiber by detecting the change of the polarization state of the light wave in the optical fiber, and has great application potential in the field of perimeter security. However, most of the current sensing research on POTDR is to directly load the vibration signal on the bare optical fiber. However, the bare optical fiber is easy to break and is difficult to be directly used in actual measurement tasks outdoors or indoors. In practical applications, it is often necessary to use optical cables with good protection for optical fibers as the sensing medium. In the POTDR experiment carried out with optical ca...

Claims

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Application Information

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IPC IPC(8): G01D5/353G01H9/00
CPCG01D5/35354G01D5/35374G01H9/004
Inventor 窦蓉蓉张子敬张伦强张元成庄建军
Owner NANJING UNIV
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