title: Group delay spread analysis of strongly coupled 3-core fibers: an effect of bending and twisting.
abstract: The effect of bending and twisting on the group delay spread (GDS) of strongly coupled 3-core fibers is investigated. For the random perturbation inducing modal coupling in the fiber, two physical mechanisms, microbending or macrobending with random twist, are considered. Calculated results show that both mechanisms lead to the same effect, namely, reduced GDS under strong coupling regime. Furthermore, a novel fiber structure having an air-hole at the center is proposed for reducing the GDS. By placing the air-hole, the effective index difference between fundamental and the higher order modes is reduced, leading to strong modal mixing in the fiber, and hence, small GDS. Calculated GDS of the fiber with air-hole is almost 1/5 compared with that of the fiber without air-hole.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fujisawa
authors.forename: Kunimasa
authors.initials: K
authors.lastname: Saitoh