Abstract:
This study investigates how macroscopic mechanical deformations, specifically bending and twisting, influence the transmission capabilities of an optical waveguide. The core of the research lies in analyzing how mechanical stresses and strains distort the optical indicatrix of the fiber's medium, which in turn produces optical anisotropy and creates spatially varying refractive indices. These spatially dependent refractive indices are incorporated directly into the full-wave Maxwell's equations, which are then discretized using a high-order vector finite element method. This numerical approach allows for the accurate modeling of complex deformations while reducing computational requirements. The study examines several fiber configurations: straight, bent at various angles, twisted at different rates, and a combination of bent and twisted. By propagating a Gaussian pulse through each configuration, the authors report on the resulting optical activities, total energy, and power loss inside the core. The findings demonstrate that bending causes an asymmetric power loss that is dependent on the bending direction. At higher bend angles, the leaked pulse can be guided back into the core. In contrast, twisting the fiber results in a symmetric, circular dispersion of the pulse that is dependent on the radial variation and is not re-guided back into the core.
