Fiber optic sensing for structural health monitoring in harsh environments advancing degradation physics signal robustness and long term reliability prediction

Fiber optic sensing (FOS) technologies have emerged as transformative platforms for structural health monitoring (SHM) of critical infrastructure operating in harsh environments. Unlike conventional electrical sensors, fiber optic sensors offer intrinsic immunity to electromagnetic interference, multiplexing capability, distributed sensing over tens of kilometres, and small footprint suitable for structural embedding. However, the transition from laboratory validation to long-term field deployment in extreme conditions including thermal extremes, high radiation fields, aggressive chemical environments, and severe mechanical loading remains impeded by a durability-reliability gap that this review systematically addresses. This paper presents the first critical synthesis integrating three foundational pillars which are the physics of environmental degradation mechanisms affecting silica and specialty optical fibers; signal robustness engineering encompassing temperature-strain decoupling, drift compensation, machine learning-enhanced denoising, and fault-tolerant network architectures; and long-term reliability science including accelerated life testing protocols, physics-of-failure modelling, and field validation case studies spanning nuclear reactors, offshore wind turbines, aerospace platforms, and extreme-climate civil infrastructure. A comprehensive gap analysis of existing standards (Telcordia GR-326, IEC 60793, MIL-STD) reveals critical deficiencies in SHM-specific qualification frameworks, and a roadmap toward standardized test protocols and regulatory acceptance pathways is proposed. Emerging frontiers including sapphire fibers, carbon nanotube coatings, physics-informed neural networks, and autonomous self-healing sensor networks are critically evaluated. The review concludes with actionable recommendations for researchers, practitioners, standards bodies, and funding agencies to accelerate the maturation and widespread deployment of reliable FOS-SHM systems in the world’s most demanding operational environments.