Brillouin gain spectrum manipulation using multifrequency pump and probe for slope-assisted BOTDA with wider dynamic range

Abstract We propose slope assisted Brillouin optical time domain analysis (SA-BOTDA) with virtual Brillouin gain spectrum (BGS) generated by multifrequency pump and probe. The virtual BGS having a wide linear slope region of 100 MHz is easily generated by employing time-to-space spectral shaping technique that has been originally developed for generating short optical pulses. We demonstrate the distribution of virtual BGS realized by using five spectral components of pump and probe.

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Effects of Pump-Pulse Width and Temperature on Experimental Brillouin Gain Spectrum Obtained from Brillouin Optical Time-Domain Analysis Sensors

Bangladesh Journal of Physics ◽

10.3329/bjphy.v27i1.49727 ◽

2020 ◽

Vol 27 (1) ◽

pp. 69-80

Author(s):

Abul Kalam Azad

Keyword(s):

Pump Pulse ◽

Time Domain ◽

Pulse Width ◽

Nonlinear Least Squares ◽

Time Domain Analysis ◽

Domain Analysis ◽

Gain Spectrum ◽

Least Squares Curve Fitting ◽

Brillouin Gain ◽

Optical Time

In this paper, the characteristics of Brillouin gain spectrum (BGS) obtained from a Brillouin optical time-domain analysis (BOTDA) sensor are investigated and analyzed experimentally. The measured BGSs obtained for various pump-pulse widths and temperatures are fitted with different spectrum profiles using nonlinear least-squares curve fitting technique. The fitting performances of used profiles are presented and analyzed. Based on such performances, the proper spectrum profile to be used in the fitting process is determined and used to extract key parameters of the measured BGSs accurately. The variations of such key parameters with pump-pulse widths and temperatures are also investigated and analyzed. The results reveal that pump-pulse widths and temperatures have significant effects on the extracted key parameters of the measured BGSs obtained from BOTDA sensors. Bangladesh Journal of Physics, 27(1), 69-80, June 2020

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

Applied Sciences ◽

10.3390/app9010058 ◽

2018 ◽

Vol 9 (1) ◽

pp. 58 ◽

Cited By ~ 2

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.

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Cost-Effective Brillouin Optical Time-Domain Analysis Sensor Using a Single Optical Source and Passive Optical Filtering

Journal of Sensors ◽

10.1155/2016/8243269 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

H. Iribas ◽

J. Urricelqui ◽

J. Mariñelarena ◽

M. Sagues ◽

A. Loayssa

Keyword(s):

Time Domain ◽

Cost Effective ◽

Optical Filters ◽

Time Domain Analysis ◽

Domain Analysis ◽

Optical Source ◽

Optical Filtering ◽

Spectral Components ◽

Optical Time ◽

The Cost

We present a simplified configuration for distributed Brillouin optical time-domain analysis sensors that aims to reduce the cost of the sensor by reducing the number of components required for the generation of the two optical waves involved in the sensing process. The technique is based on obtaining the pump and probe waves by passive optical filtering of the spectral components generated in a single optical source that is driven by a pulsed RF signal. The optical source is a compact laser with integrated electroabsorption modulator and the optical filters are based on fiber Bragg gratings. Proof-of-concept experiments demonstrate 1 m spatial resolution over a 20 km sensing fiber with a 0.9 MHz precision in the measurement of the Brillouin frequency shift, a performance similar to that of much more complex setups. Furthermore, we discuss the factors limiting the sensor performance, which are basically related to residual spectral components in the filtering process.

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