Intensifying Brillouin distributed fibre sensors using image processing

Abstract

Image processing is proposed to enhance the performance of Brillouin distributed fibre sensors. The technique exploits the two-dimensional nature of the measurements, so that each frequency-position pair is assimilated to a pixel of a noisy image. Based on the level of redundancy existing in the two-dimensional information, the method offers unmatched denoising capabilities when compared to classic unidimensional denoising methods, even if those ones are consecutively used in distance and frequency domains. With no modification of the basic configuration, up to ~14 dB SNR improvement is experimentally demonstrated with unobservable loss of spatial resolution. A figure-of-merit of 115'000 is verified.

Novel scanning method for distortion-free BOTDA measurements

“…It should be highlighted that this kind of measurements at 100 km with 2 m resolution are basically impossible to perform with conventional DSB setups. These performances can only be reached by using range enhancement techniques such as pump pulse coding [12,13], Raman assistance [14,15], image processing [16,17] or combinations of them [18,19]. This comes from the low SNR resulting from the reduced probe power (<-5 dBm/sideband) required to avoid spectral distortions in the measurements and the large cumulated fiber loss (20 dB for 100 km sensing range) experienced by the probe before reaching the detector.…”

“…Making use of the improved operating conditions demonstrated before for the proposed scheme and owing to the increased probe power, measurements along 100 km with 2 m resolution turned possible without the need of additional advanced methods, such as coding techniques [12,13], distributed amplification [14,15], image processing [16,17] or some combinations of them [18,19]. Figure 13(a) shows the BOTDA amplitude trace at the averaged peak gain frequency (pump-probe frequency shift of ~10.856 GHz) along the 100 km fiber span.…”

“…Actually, methods such as pulse coding [12,13], Raman distributed amplification [14,15], image processing [16,17], and some combinations of them [18,19] have allowed a significant boost in SNR and sensor performance; however, their capability to enable implementations with very high figure-of-merit [6] has been compromised by the use of low probe power levels, thus preventing those advanced techniques from performing at their maximum potential. Providing a solution to pump depletion issues, which could also enable the use of advanced methods, would be a significant step forward to enhance the performance of BOTDA sensors.…”

“…An important aspect of the reported phenomenon is that it affects not only standard BOTDA configurations [6][7][8][9]11], but also any other advanced technique making use of the DSB/SSB probe scheme [12][13][14][15][16][17][18][19]. Actually, methods such as pulse coding [12,13], Raman distributed amplification [14,15], image processing [16,17], and some combinations of them [18,19] have allowed a significant boost in SNR and sensor performance; however, their capability to enable implementations with very high figure-of-merit [6] has been compromised by the use of low probe power levels, thus preventing those advanced techniques from performing at their maximum potential.…”

Novel Concepts and Recent Progress in Distributed Optical Fiber Sensing

“…In a pure transdisciplinary approach, powerful algorithms employed to improve the quality of an image can be applied on the data represented in Fig. 2b, in particular image denoising procedures [16]. These advanced algorithms analyze the image by defining 2D windows on which sophisticated nonlinear averaging procedures are applied, thus relying on redundancies and similarities in the image.…”