Synthesis and Properties of Perfluorinated Polyimides

Abstract

Silica-based single-mode optical fibers are used as the transmission medium in current optical telecommunication systems.1 The transmission light is near-IR. Degradation of communication quality under transmission is minimized by using a 1.3 μm wavelength because the refractive index dispersion of these optical fibers is zero at this wavelength, which is thus called the zero-dispersion wavelength. On the other hand, this optical fiber has a minimum transmission loss at 1.55 μm. Techniques have been developed to shift the zero-dispersion wavelength of silicabased optical fibers to 1.55 μm. Future telecommunication subscriber systems will use both 1.3 and 1.55 μm as communication wavelengths2 (e.g., 1.3 μm for communication service and 1.55 μm for one-directional video service). The refractive index of the core of the optical fibers is made slightly higher than that of the cladding in order to confine the transmitted optical signals. A small amount of GeO2 is doped into the core of the commonly used silica-based optical fibers in order to increase the refractive index. Since doping into the core is undesirable from the point of view of decreasing the transmission loss, fluorine is doped into the cladding of optical fibers to achieve very low transmission loss. The