Fundamental studies on flat bunched optical fibers

To produce an ultra-high fiber count optical cable with ultra-high density for subscriber loop applications, a new multicore fiber format, called "flat bunch fiber" format has been developed and manufactured. Individual cores in a flat bunch fiber format were arranged in a line contacted with neighboring claddings. This new format gave some advantages over existing optical fibers, from high density and mass-spliceability viewpoints. In this paper, fundamental characteristics of a flat bunch fiber, such as optical loss, bending, microbending, and tensile strength were mainly studied experimentally, comparing with an existing fiber. As a result, good characteristics to use in practice were shown. Moreover, crosstalk, which was one item of great concern for this kind of optical fiber, was the order to -40 dB for 500-m long optical fiber.