POLYMER OPTICAL-FIBER WITH HIGH THERMAL-STABILITY AND LOW OPTICAL LOSSES BASED ON NOVEL DENSELY CROSS-LINKED POLYCARBOSILOXANES

A multimode step-index polymer optical fiber has been developed based on a highly crosslinked polycarbosiloxane as the core material and a f luorinated polyolefin (poly(fluoroethylene-co-fluoropropylene)-FEP) cl adding layer. The combination offered a system with a high thermal sta bility, both optically and dimensionally, up to at least 200 degrees C . The polymer optical fiber was produced by injection of a poly(phenyl methylvinylhydro)siloxane crosslinkable prepolymer in an FEP tubing, a fter which the prepolymer was cured in situ. From attenuation measurem ents losses as low as 0.98 dB/m at 780 nm were found. The refractive i ndices of the core material and the cladding are 1.48 and 1.30, respec tively. The large difference in refractive index results in a high val ue for the numerical aperture of 0.70. The prepolymer is a single-comp onent, self-crosslinking, and conveniently processable system. The com bination of a low attenuation and easy processability makes these mate rials very suitable not only for polymer optical fibers, but for all k inds of optical components. (C) 1998 John Wiley & Sons, Inc.