Fano resonances in kagome fibers

Confinement Loss of microstructured fibers whose cladding is composed by a triangular arrangement of tubes of various shapes is theoretically and numerically investigated. Kagome Fibers belong from this family of fibers with cladding tubes with hexagonal shape. The shape of the cladding tubes is proved to strongly affect the performance of the microstructured fiber. In order to understand the reasons for this behavior, the spectral properties of the tubes that constitute the cladding are investigated first. It is proved that also these tubes suffer from additional Fano Resonances when they are given a polygonal shape. It is proved that, by using the analytical model developed for the stand alone polygonal tubes, it is possible to predict the spectral position of Fano Resonances also in microstructured fibers. This is extremely important since it suggest new ways to reduce confinement loss in kagome fibers and microstructured fibers in general.