The Influence of Refractive Index Disturbance of Ring-core Fiber with Central Air Hole on Modes Separating

In this paper, the influences of the ring thickness, the maximum refractive index of the ring and curve steepness on the mode separation are analyzed. The model is established with considering the actual fiber fabrication, especially the transition range between two adjacent layers are studied. Then we manufacture the ring-core fiber with central air hole. This study has reference significance for the structure design of vortex optical fibers.