Mitigating Hysteresis in Metal-Coated Fibers via Optimized Thermal Treatment for Advanced Distributed High-Temperature Sensing Applications

作者：Koustav Dey, Rony Kumer Saha, B. Zhang, S. Narasimman, Farhan Mumtaz, Jeffrey D. Smith, Rex E. Gerald, Ronald J. O’Malley, Jie Huang · 发表于：IEEE Transactions on Instrumentation and Measurement · 年份：2026 · DOI：10.1109/tim.2026.3652753 · 被引用次数：4 · 研究领域：Advanced Fiber Optic Sensors、Electrical and Thermal Properties of Materials、Thermography and Photoacoustic Techniques

Metal-coated optical fibers are widely employed in sensing applications owing to their superior mechanical strength and corrosion resistance. However, their calibration at elevated temperatures is hindered by hysteresis, manifested as discrepancies between heating and cooling cycles, primarily caused by residual strain from mismatched thermal expansion coefficients (TECs) between the metal coating and silica cladding. This research introduces an optimal heat treatment procedure aimed at minimizing the impact of the mismatch in TECs between the cladding and the coating materials that causes the residual strain in gold (Au) and copper (Cu) coated fibers for achieving reliable distributed high temperature sensing up to 500 °C using Optical Frequency Domain Reflectometry (OFDR) technology. The treatment facilitates stress relaxation and microstructural modifications, including surface diffusion, grain growth and oxidation (for Cu coatings), which collectively induce partial interfacial delamination and thereby suppress hysteresis. This work presents the first comprehensive experimental study to systematically investigate and demonstrate the mitigation of hysteresis through an optimized heat treatment process and its underlying mechanisms in metal-coated fibers, supported by microstructural insights. The identified treatment range of 25–300 °C achieves substantial reductions in residual strain, lowering hysteresis effects by approximately 90.2% in Cu-coated fibers and 86.6% in Au-...