Distributed and discrete hydrogen monitoring through optical fiber sensors based on optical frequency domain reflectometry

Abstract

The potential of discrete and distributed fiber-based sensors exploiting the Rayleigh scattering signature of doped amorphous silica is investigated for the real time monitoring of molecular hydrogen (H 2 ) detection. We showed that the impact of the refractive index changes induced by the H 2 diffusion into the silica host matrix can be used to detect and quantify this gas presence through two approaches: first via the related fiber length variation and second through the observed spectral shift. Comparing the obtained results with H 2 diffusion calculations, we can estimate the sensor sensitivity thresholds to be ∼10 16 n molecule cm −3 for the distributed measurements (spatial resolution better than 1 mm) and below ∼10 19 n molecule cm −3 for the discrete-one. The presented architecture of the sensor is well adapted to the monitoring of slowly evolving H 2 concentrations such as the ones expected in nuclear waste repositories as the time response of the sensor remains limited by the diffusion of the gas within the optical fiber. These threshold values and time responses can be easily improved by optimizing the length, the composition and/or the geometry of the sensing fiber.

Machine Learning Applications in Optical Fiber Sensing: A Research Agenda

“…Left ventricular assist devices (LVAD) and mild traumatic brain injury are terms in Quadrant II. These terms refer to key areas of research where fiber optic sensing and machine learning have been used to solve critical healthcare problems [31,96,97]. For example, fiber-sensing technology has been used to improve LVAD monitoring and control.…”

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Recent advances in radiation-hardened fiber-based technologies for space applications

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Machine Learning Approaches in Brillouin Distributed Fiber Optic Sensors

“…This has already made DFOSs attractive for a wide range of applications, including structural health monitoring of civil and geotechnical structures [1][2][3][4][5], pipeline and borehole monitoring for leak detection [6], seismic activity monitoring [7][8][9][10] or even the condition monitoring of high-voltage submarine cables [11] and deep earth dynamics in oceans [12]. Even though the most common measurands are temperature and strain, DFOSs can directly or indirectly measure the humidity [13][14][15], pressure [16], displacement [4,17], radiation [18][19][20], gas concentration [21,22], etc.…”