A new gas detection technique through cross-correlation with a complex aperiodic FBG

• Published in: Scientific reports Vol. 14; no. 1; p. 9939
• Main Authors: Rahme, Matthew, Tuthill, Peter, Betters, Christopher, Large, Maryanne, Leon-Saval, Sergio
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30.04.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/1075/1079; 639/624/1075/1083; 639/624/1075/187; 639/624/1107/527/2257; 639/624/400/385; Absorption; Acetylene; Contaminants; Correlation; Cross-correlation spectroscopy; Fiber Bragg gratings; Gas detection; Gases; Humanities and Social Sciences; multidisciplinary; Optical filters; Science; Science (multidisciplinary); Signal-to-noise ratio; Optical filters; Fiber Bragg gratings; Cross-correlation spectroscopy; Gas detection
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-024-59841-7

Optical cross-correlation is a technique that can achieve both high specificity and high sensitivity when deployed as the basis for a sensing technology. Offering significant gains in cost, size and complexity, it can also deliver significantly higher signal-to-noise ratios than traditional approaches such as absorption methodologies. In this paper, we present an optical cross-correlation technology constructed around a bespoke customised Fiber Bragg Grating (FBG). Exploiting the remarkable flexibility in design enabled by multiple aperiodic Bragg gratings, optical filters are devised that exactly mimic the absorption features of a target gas species (for this paper, acetylene C 2 H 2 ) over some waveband of interest. This grating forms the heart of the sensor architecture described here that employs modulated optical cross-correlation for gas detection. An experimental demonstration of this approach is presented, and shown to be capable of differentiating between different concentrations of the C 2 H 2 target gas. Furthermore these measurements are shown to be robust against interloper species, with minimal impact on the detection signal-to-noise arising from the introduction of contaminant gases. This represents is a significant step toward the use of customised FBGs as low-cost, compact, and highly customisable photonic devices for deployment in gas detection.