Significance Hydrogen energy, with its high energy density and renewability, has emerged as a preferred solution to address environmental challenges and optimize energy structures. However, safety concerns related to hydrogen leakage and abnormal concentration fluctuations remain critical barriers to its widespread adoption. Consequently, the development of reliable technologies for real-time hydrogen monitoring is of paramount importance. Among various detection methods, optical fiber-based hydrogen sensing technology has garnered significant attention due to its exceptional advantages, including intrinsic safety, immunity to electromagnetic interference, compact size, and suitability for remote and distributed monitoring. This paper provides a comprehensive review of recent advancements in optical fiber hydrogen sensing technologies, with a focus on elucidating the interaction mechanisms between hydrogen-sensitive materials and hydrogen molecules, as well as analyzing the structural characteristics and performance metrics of diverse sensor configurations.
Progress Significant progress has been made in the design and optimization of hydrogen-sensitive materials such as palladium (Pd) and its alloys, tungsten oxide (WO
3), and graphene-based composites. These materials enable hydrogen detection through mechanisms such as refractive index changes due to chemisorption, plasma effects, and others. Fiber optic sensor structures, such as fiber Bragg gratings (FBGs), long-period gratings (LPGs), and Fabry-Perot interferometers, have been extensively explored. For example, palladium-coated fiber Bragg grating sensors exhibit fast response times (less than 30 seconds) and high sensitivity (33 pm/vol%), while fiber grating hydrogen sensors integrating tungsten oxide amplify the hydrogen response sensitivity by a factor of 16.11 using the vernier effect. Recent innovations, such as structural functionalized sensors using palladium nano-arrays and hybrid plasma-photonic sensors, have further increased the detection limit to sub-ppm levels.
Despite these advancements, challenges persist in balancing sensitivity, response speed, long-term stability, and environmental adaptability. Material degradation under cyclic hydrogen exposure and cross-sensitivity to temperature fluctuations remain critical issues. Future research directions include the development of novel nanocomposite coatings, advanced signal demodulation algorithms, and multi-parameter sensing platforms. Additionally, the integration of artificial intelligence for real-time data processing and the implementation of sensor networks for large-scale infrastructure monitoring represent promising avenues.
Conclusion and Prospects Optical fiber hydrogen sensors exhibit immense potential for ensuring safety in hydrogen-related applications, particularly in scenarios requiring explosion-proof operation, remote monitoring, and distributed sensing across complex systems. As key technical hurdles—such as material durability and system miniaturization—are progressively addressed, these sensors are poised to play a pivotal role in advancing the commercialization and large-scale deployment of hydrogen energy. Their evolution will not only enhance safety protocols but also accelerate the global transition toward sustainable energy ecosystems. This review underscores the transformative impact of optical fiber sensing technologies in realizing a hydrogen-powered future.