Enhancement of Strain/Temperature Measurement Range and Spatial Resolution in Brillouin Optical Correlation Domain Analysis Based on Convexity Extraction Algorithm

Abstract

We propose and experimentally demonstrate a novel method to enhance the performance of the Brillouin optical correlation domain analysis (BOCDA) by analyzing the shape characteristic of the measured Brillouin gain spectrum. We theoretically analyze and simulate the operation of BOCDA, and it is found that the Brillouin signal peak generated at the correlation peak shows a sharp Lorentzian shape with a large value of convexity, while the background noise structure stacked from other positions shows a smooth trapezoidal shape with a small value of convexity. By extracting the convexity of measured BGS, the signal part can be enhanced while the noise part is suppressed drastically, which leads to an enlarged strain/temperature measurement range and a narrowed spatial resolution for BOCDA. This concept is verified by both numerical simulation and experiments. By using this method, a >16-mε/800-• C strain/temperature measurement range and a fivefold-improved spatial resolution are achieved experimentally without extra hardware complexity.

High-Spatial-Resolution Dynamic Strain Measurement Based on Brillouin Optical Correlation-Domain Sensors

“…Meanwhile, al. proposed a BGS reconstruction algorithm to further improve the SR to 8 cm ov m fiber and extend the strain range to 800 MHz [46]. To address the lack of flexibility due to the double-end access to the fiber in the conventional BOCDA system, a single-end sine-FM BOCDA system was proposed in 2019, which can provide an ultrahigh sampling rate, single-end access, a large dynamic range, and high SR simultaneously [45].…”

“…For 3, there is a trade-off problem between the high accuracy or wide range and fast measurement. In order to achieve high-speed and real-time measurement, especially of dynamic strain caused by vibration, fast Brillouin DOFSs based on fast-sweep [39][40][41][42][43][44][45][46][47][48][49][50][51][52], sweep-free [53][54][55], and slope-assisted [56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71] methods have been proposed.…”

Recent Progress in Long-Range Brillouin Optical Correlation Domain Analysis

“…In 1999 and 2000, the first realization of BOCDA was proposed based on a frequency modulation (FM) source using a sinusoidal wave, where a 40 cm resolution is demonstrated, and the obstacles for the conventional pulse-based techniques are overcome [11,12]. Moreover, several enhanced schemes have been proposed to achieve a higher resolution, such as the three-electrode laser with a large push-pull-type current [13], intensity modulation [14][15][16], convexity extraction algorithm [17], etc. [18,19].…”

Recent progress in slope-assisted Brillouin optical correlation-domain reflectometry

“…Their performance has been dramatically enhanced, and even sub-centimeter spatial resolution and real-time operation have been achieved. Another Brillouin-based distributed sensing technique is a correlation-domain technique, which include Brillouin optical correlation-domain analysis (BOCDA) [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] and Brillouin optical correlationdomain reflectometry (BOCDR) . These techniques have not only sub-centimeter spatial resolution but also a unique advantage of random accessibility to measuring points.…”