Improvement of the measurement accuracy of distributed Brillouin sensing via radio frequency filtering

Schneider

2021

Sensors

Self Cite

As one of the most consolidated distributed fiber sensors based on stimulated Brillouin scattering, the Brillouin optical time-domain analyzer (BOTDA) has been developed for decades. Despite the commercial availability and outstanding progresses which has been achieved, the intrinsic Lorentzian gain spectrum restricts the sensing performance from possible further enhancements and hence limits the field of validity of the technique. In this paper, the novel method of engineering the gain spectral properties of the Brillouin scattering and its application on static and dynamic BOTDA sensors will be reviewed. Such a spectral property engineering has not only provided improvements to BOTDA, but also might open a new way to enhance the performance of all kinds of distributed Brillouin fiber sensors.

Section: Benefits Of Brillouin Spectral Property Engineering In Stmentioning

confidence: 99%

Benefits of Spectral Property Engineering in Distributed Brillouin Fiber Sensing

Schneider

2021

Sensors

Self Cite

“…Long-term stability would require active stabilization. A DC-270 MHz low pass filter at the output of the main photodetector (PD) [33], [34], limits the noise at the input of the digital recording oscilloscope, while being wide enough to preserve the spatial resolution offered by the temporal characteristics of the pump pulse. Triggering of both the pump pulse and trace recording are controlled by the DTG.…”

Section: Experiments a Setupmentioning

confidence: 99%

Gain Spectrum Engineering in Slope-Assisted Dynamic Brillouin Optical Time-Domain Analysis

Bhatta

Bohbot

et al. 2020

J. Lightwave Technol.

Self Cite

Slope-Assisted Brillouin Optical Time Domain Analysis (SA-BOTDA) is a fast and distributed sensing technique that interrogates the Brillouin gain spectrum (BGS) near the middle of the linear region of its slope, allowing the measurement of high frequency vibrations. However, environmentally-induced deviations of the interrogation point from the rather small linear region around the optimum frequency position, result in harmonic distortion and changes in the slope value, which determines the gain-to-frequency conversion factor. Engineering the BGS by adding a loss probe, we propose a novel and improved version of SA-BOTDA, having a significantly wider drift tolerance for the interrogation point. Here, using a 14 ns pump pulse and a judicious choice of the frequency of the loss probe, we demonstrate an engineered BGS having a 70% wider frequency range (as compared with the conventional BGS), where the interrogation point can drift without compromising either the prescribed level of harmonic distortion or the given slope tolerance, further benefiting the flexibility and usage of SA-BOTDA.

“…The averaging increases the measurement time significantly and limits real-time acquisition, particularly in dynamic sensing applications [ 16 , 17 ]. Many approaches like wavelet de-noising techniques [ 18 ], 2D and 3D image restoration [ 19 ] and the employing of radio frequency (RF) low pass filtering [ 20 ] have been applied to reduce the noise level in BOTDA. Nevertheless, these methods might increase the post-processing time.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Noise Induced by Stimulated Brillouin Scattering in Distributed Sensing

Kadum

Schneider

2020

Sensors

Self Cite

The excess noise due to stimulated Brillouin scattering (SBS) in gain and loss-based Brillouin optical time-domain analyzers (BOTDA) has been investigated theoretically and experimentally for the first time to the best of our knowledge. This investigation provides a full insight to the SBS-induced noise distribution, which mainly comes from phase-to-intensity conversion noise and the beating noise between the probe wave and spontaneous Brillouin scattering. A complete theoretical model, which is in good agreement with the experimental results, is presented to describe the noise. The results show that a loss-based BOTDA setup gives a better noise performance than a gain-based one in both time and frequency domain. The SBS-induced noise has been characterized in dependence on the pump and probe power and the spatial resolution.