Transition Layer and Surface Roughness Effects on the Response of Metal-Based Fiber-Optic Corrosion Sensors

This paper presents experimental results, approximate analytical formulations, and numerical simulation results to analyze the reflectance from a metalized fiber tip under corrosion, which is part of a corrosion sensor. Moreover, the dynamics of corrosion on a thin metallic film is modeled computationally by considering a proposed roughness fitting function to consider the evolution of film thickness and shape during the corrosion process. For this modeling, COMSOL Multiphysics is used to simulate the optical signal reflected from the transducer element of the sensor. The simulation results for the optical signal reflected from a rough metallic film are compared with experimental and analytical results. The results reveal that the corrosion process generates an inhomogeneous metallic structure that allows the occurrence of surface plasmon resonance, and the proposed simple surface roughness model can be used to describe the dynamic process of corrosion of an aluminum film that is deposited on the end-facet of an optical fiber.