Theoretical and numerical studies on macrobending losses in multimode fibers.

摘要

This dissertation reports the background, theory, and numerical studies of bending losses in multimode optical fibers, including effects of mechanical deformation. We justify the use of a ray model by calculating the total number of modes in multimode fibers of practical interest. We theoretically extend Jacomme's model for ray tracing to bent multimode graded-index fibers, including a detailed consideration of mechanical deformation. We use numerical methods to solve the ray tracing differential equations and compute the bending losses for a variety of initial ray distributions, including models of laser and LED illumination. We compare the computed results with published data and conclude that the numerical results match well with empirical data for bending radii larger than 3 cm. Future work will focus on a modified model for smaller bending radii by taking into account torsional strain introduced during bending loss tests.