High-Sensitivity Hydrogen Detection with Tantalum Metal Hydride-Coated Tilted Fibre Bragg Gratings
Kasun Prabuddha Dissanayake (TU Delft - Aerospace Engineering)
Ziqing Yuan (TU Delft - Applied Sciences)
Herman Schreuders (TU Delft - Applied Sciences)
Théo Travers (TU Delft - Aerospace Engineering)
Lars J. Bannenberg (TU Delft - RID/TS/Instrumenten groep)
Roger M. Groves (TU Delft - Aerospace Engineering)
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Abstract
This article presents the development and characterization of a tilted fiber Bragg grating (TFBG) hydrogen sensor functionalised with a nanometre-scale multilayer thin film stack comprising tantalum (Ta), palladium-gold (Pd0.6Au0.4), and polytetrafluoroethylene (PTFE). Ta is introduced as a novel optical fiber sensing material for hydrogen detection, offering unique advantages in sensitivity, reversibility, and hysteresis-free behavior. The optical design of the TFBG ensures efficient coupling to cladding modes, enabling a stable and repeatable hydrogen-induced spectral response when coated with Ta. The sensor was tested over a wide hydrogen concentration range from 0.001% to 100% H
2 at room temperature. Experimental results demonstrate a measurable and reversible optical response in the mean center wavelength of the cladding mode resonances, averaged over the 1520–1580-nm spectral envelope, with a minimum detection limit of 0.001% (~10 ppm) H
2 and a maximum mean wavelength shift of approximately 15 pm at 100% H
2. The Ta coating provides excellent optical performance, characterized by an absence of hysteresis and a large, nearly constant relative sensitivity across an exceptionally wide sensing range spanning at least five orders of magnitude in hydrogen concentration. Sensor stability and repeatability were further confirmed through extended cycling between 0.1% and 4% H
2, validating the robustness of the cladding mode response. These results highlight both the unique TFBG-based optical architecture and the role of Ta as a highperformance coating, supporting the potential of the Ta-TFBG sensor for sensitive, low-level hydrogen detection in aerospace and energy applications.
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