scholarly journals Improvement of Performance for Raman Assisted BOTDR by Analyzing Brillouin Gain Spectrum

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 116
Author(s):  
Qiang Huang ◽  
Junqiang Sun ◽  
Wenting Jiao ◽  
Li Kai
Keyword(s):  
Spatial Resolution ◽  
Measurement Accuracy ◽  
Gain Spectrum ◽  
Analysis Method ◽  
Optical Time Domain Reflectometer ◽  
Starting Point ◽  
First Occurrence ◽  
Brillouin Gain ◽  
Optical Time ◽  
The Mathematical Model

We propose a simplified partitioned Brillouin gain spectrum (BGS) analysis method to enhance the spatial resolution and measurement accuracy of a Brillouin optical time-domain reflectometer (BOTDR) assisted by a first-order Raman pump. We theoretically derive the mathematical model of the partitioned BGS and analyze the superposition process of sub-Brillouin signals within a theoretical spatial resolution range. We unified all the unknown constant parameters of the calculation process to simplify the partitioned BGS analysis method and the value of the uniform parameter is attained through the system test data and numerical analysis. Moreover, to automate data processing, the starting point of the temperature/strain change is determined by the first occurrence of the maximum Brillouin frequency shift (BFS), then the position where the partitioned BGS analysis method calculation begins is obtained. Using a 100 ns probe pulse and partitioned BGS analysis method, we obtain a spatial resolution of 0.4 m in the 78.45-km-long Raman-assisted BOTDR system, and the measurement accuracy is significantly improved. In addition, we achieve a strain accuracy of 5.6 με and a spatial resolution of 0.4 m in the 28.5-km-long BOTDR without Raman amplification.

scholarly journals The Influence of Laser Linewidth on the Brillouin Shift Frequency Accuracy of BOTDR

2018 ◽  
Vol 9 (1) ◽  
pp. 58 ◽  
Author(s):  
Qing Bai ◽  
Min Yan ◽  
Bo Xue ◽  
Yan Gao ◽  
Dong Wang ◽  
...  
Keyword(s):  
Probe Pulse ◽  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Gain Spectrum ◽  
Laser Source ◽  
Laser Linewidth ◽  
Optical Time Domain Reflectometer ◽  
Brillouin Gain ◽  
Optical Time ◽  
Shift Frequency

This paper analyzes the influence of laser linewidth on the measurement accuracy of a frequency-scanning Brillouin optical time domain reflectometer (FS-BOTDR), allowing for both the width of Brillouin gain spectrum and the signal-to-noise ratio (SNR) of the BOTDR system. The measurement accuracy of the Brillouin frequency shift (BFS) is theoretically investigated versus the duration of the probe pulse and the linewidth of the laser source, by numerically simulating how a FS-BOTDR works and evaluating the Brillouin gain spectrum (BGS) width and the system SNR. The simulation results show that the BFS accuracy is improved as the laser linewidth becomes narrower when the probe pulse width is fixed. We utilize five types of lasers with respective linewidths of 1.05 MHz, 101 kHz, 10.2 kHz, 3.1 kHz, and 98 Hz to compare the BFS measurement accuracy over a ~10 km optical sensing fiber. The experimental results demonstrate that the root-mean-square error (RMSE) of BFS decreases with the laser linewidth narrowing from 1.05 MHz to 3.1 kHz, which is in good agreement with the numerical simulation. However, the RMSE of BFS increases when the laser linewidth is less than 3.1 kHz, which may arise from the coherent Rayleigh noise due to a too narrow laser linewidth. The results can provide a theoretical basis and experimental guidance for choosing the appropriate laser linewidth in BOTDR.

Improvement of Spatial Resolution for Strain Measurement with Brillouin Optical Time-Domain Reflectometer by Fitting Method Based on Equivalent Optical Pulse

2008 ◽  
Vol 28 (1) ◽  
pp. 43-49 ◽  
Author(s):  
王峰 Wang Feng ◽  
张旭苹 路元刚'南京大学光通信工程研究中心 Zhang Xuping ◽  
江苏 南京 Lu Yuangang ◽  
董玉明 Dong Yuming
Keyword(s):  
Spatial Resolution ◽  
Time Domain ◽  
Strain Measurement ◽  
Optical Pulse ◽  
Optical Time Domain Reflectometer ◽  
Fitting Method ◽  
Optical Time ◽  
Time Domain Reflectometer

The Performance Analysis of Fiber Distributed Vibration Monitoring Technology Based on φ-OTDR

2013 ◽  
Vol 336-338 ◽  
pp. 192-195
Author(s):  
Ji Qiang Wang ◽  
Yuan Liu ◽  
Mo Yu Hou ◽  
Lin Zhao ◽  
Tong Yu Liu
Keyword(s):  
Spatial Resolution ◽  
Sampling Rate ◽  
Vibration Monitoring ◽  
Monitoring Technology ◽  
Optical Time Domain Reflectometer ◽  
Response Range ◽  
Phase Sensitive ◽  
Point Positioning ◽  
Optical Time ◽  
Time Domain Reflectometer

The performance of the fiber distributed vibration monitoring technology based on the phase sensitive optical time domain reflectometer (φ-OTDR) is reseached. the principle of fiber distributed vibration monitoring of the φ-OTDR and multi-point positioning are illustrated. And this paper indicates the feasibility of realizing multi-point positioning by the φ-OTDR system, and carry on a further research on the φ-OTDR system ́s frequency response range, measuring distance, spatial resolution and other aspects. The inverse proportion relations between the frequency range and distance of the φ-OTDR system, and the relations among spatial resolution, laser pulse width, refractive index and sampling rate are illustrated.

Reflectometric measurements of thermally expanded core area

2010 ◽  
Vol 58 (4) ◽  
pp. 513-517 ◽  
Author(s):  
M. Ratuszek ◽  
Z. Zakrzewski ◽  
J. Majewski
Keyword(s):  
Time Domain ◽  
Theoretical Calculations ◽  
Single Mode ◽  
Core Area ◽  
Analysis Method ◽  
Optical Time Domain Reflectometer ◽  
Mode Field ◽  
Optical Time ◽  
Time Domain Reflectometer

Reflectometric measurements of thermally expanded core area In this work an analysis method of one-way optical time domain reflectometer (OTDR) measurements has been presented. This method uniquely confirms mode field radii matching in diffusion transit area of the thermally expanded core (TEC) of thermally connected single mode telecommunication fibers. A comparison of reflectometric measurements with theoretical calculations of losses in TEC areas has been demonstrated.

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