Genetic-optimised aperiodic code for distributed optical fibre sensors

Abstract

Distributed optical fibre sensors deliver a map of a physical quantity along an optical fibre, providing a unique solution for health monitoring of targeted structures. Considerable developments over recent years have pushed conventional distributed sensors towards their ultimate performance, while any significant improvement demands a substantial hardware overhead. Here, a technique is proposed, encoding the interrogating light signal by a single-sequence aperiodic code and spatially resolving the fibre information through a fast post-processing. The code sequence is once forever computed by a specifically developed genetic algorithm, enabling a performance enhancement using an unmodified conventional configuration for the sensor. The proposed approach is experimentally demonstrated in Brillouin and Raman based sensors, both outperforming the state-of-the-art. This methodological breakthrough can be readily implemented in existing instruments by only modifying the software, offering a simple and cost-effective upgrade towards higher performance for distributed fibre sensing.

High-Performance Distributed Brillouin Optical Fiber Sensing

“…Extending the sensing range for distributed Brillouin optical fiber sensors is always a perpetual topic, and a long sensing distance is vital for the monitoring of large-scale infrastructures, such as oil/gas pipelines and power lines [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58]. However, due to the Kerr effect [39,40] and non-local effect [41][42][43], the sensing range is usually limited to a few tens of kilometers.…”

Reconstruction Compression Correlation Demodulation for Raman Optical Time Domain Reflection

“…Distributed optical fiber sensors are mainly divided into the Rayleigh fiber-optic sensors, [12,13] the spontaneous/stimulated Brillouin fiber-optic sensors, [14,15] and the spontaneous Raman fiber-optic sensors. [16][17][18][19] Among these approaches, the Raman optical time domain reflection (ROTDR) sensor has become a research hotspot due to its distributed temperature detection, [18] simple device, [19] fast measurement speed, [9] etc. In ROTDR, the spatial resolution is an extremely important performance index, it represents the smallest unit or the smallest measuring blind zone that the system can distinguish.…”

“…[28,29] Therefore, improving the spatial resolution of the system while maintaining a long sensing distance is a critical problem for the ROTDR. Recently, some advanced demodulation methods are developed, such as special fiber sensing, [26,27] optical pulse coding, [19,[30][31][32] and deconvolution algorithm. [33] The special fiber sensing technology, such as few-mode fiber (FMF), can suppress the influence of intermodal dispersion over the long sensing distance.…”

“…[26] The 1.04 and 2.58 m spatial resolution performance at 19.09 and 21.7 km are demonstrated based on the graded-index FMF. [27] The optical pulse coding technologies, such as cyclic pulse codes, [31,32] simplex codes, [30] and genetic-optimized codes, [19] are also proposed based on either directly or externally modulated semiconductor lasers. The optical pulse coding is conceptually the most cost effective.…”

“…The optical pulse coding is conceptually the most cost effective. [19] It can allow more light flux to be injected into the sensing fiber without changing the pulse width. It can extend the effective sensing distance of the system while maintaining the spatial resolution.…”