Different implementations of G.657B bend-insensitive single-mode fibers with ultra-low bend losses, still compatible to G.652D

摘要

Single Mode Fibers (SMF) showing improved bending resistance compared with standard G.652D SMF are mandatory for the Fiber-to-the-Home deployment (cf. ITU-T G657A&B recommendation). Different profile designs allow reaching G.657B bend-losses levels while staying compatible with the legacy G.652D recommendation. They all exhibit a depressed refractive index area in the cladding layer near the core that enables improved confinement of the light to the core area. Recently, questions have been raised concerning the bend-loss for extreme conditions; suggestions have been made to specify fiber bend radius as low as 5 mm. In this paper we address this development and compare the performances of three different types of structures, as well as standard step-index fibers (i.e. without any cladding assistance) for the sake of comparison. At last, we discuss the impact of the heterogeneity of the profile over a cross section on the fiber characteristics and in particular on the bend-loss performances.