Modeling and Analysis of Fiber Optic Bragg Grating Shape Sensors

The present work aims at modeling of fiber Bragg gratings (FBG) used as shape sensors. FBGs, which are commonly used for sensing physical parameters (e.g., strain, temperature, pressure), can be effectively used for shape detection in flexible bodies. They can be embedded in flexible structures for in-situ measurement of curvature. In order to design the embedded sensors and identify the spectral response of FBG, the effects of different geometrical and structural parameters on the optical response of the fiber should be investigated. In this paper, an opto-mechanical model is developed to assess the shape detection with FBGs. In the proposed model, non-symmetric coating of optical fibers with metallic materials is investigated. The model is a combination of structural and optical analyses; the structural analysis is used to find the change in optical properties of the sensor due to photo-elastic effect and the optical analysis is conducted to find the spectral response of FBG. It is shown that the non-symmetric coating can increase the sensitivity of the sensor. While the bare sensor shows little sensitivity to the curvature, the sensitivity increases with non-symmetric coating.