Stress Sensitivity Analysis of Optical Fiber Bragg Grating-Based Fabry-Perot Interferometric Sensors

A stress sensitivity analysis of optical fiber-based Fabry-Perot (FP) sensors has been performed, taking into account the influence of fiber loss on the interferometric sensitivity. The sensitivity increases proportionally with the interferometric cavity length, but it decreases with the attenuation present along the optical path. In addition, fibers constructed from materials with lower Young's modulus provide higher intrinsic stress sensitivity. In this study, three fiber materials have been studied: fused silica, poly (methyl methacrylate) (PMMA), and cyclic transparent optical polymer (CYTOP), which have different Young's modulus and optical attenuation. In general, PMMA-based FPs are best for the shortest cavity lengths due to their lower Young's modulus, the performance of silica dominates for long cavities due to the lowest fiber loss and CYTOP is the best choice for medium length cavities. The boundaries between the three length regimes depend on the operating wavelength (which strongly influences the fiber loss) and the reflectivity of the mirrors forming the interferometer. Where the mirrors take the form of fiber Bragg gratings, the grating length also impacts the system performance. The presented model can be used to identify which material offers the highest stress sensitivity when the physical and optical characteristics of a FP stress sensor have been predefined.