High Performance Graded Index Polymer Optical Fibers

摘要

Experimental and theoretical studies of the optical properties of large core stepindex (SI) plastic optical fibers (POF) and graded index (GI) POFs are reported. A set of criteria and analyses of physical parameters are developed in context to the major issues of POF applications in short-distance communication systems. Analyses are presented to show how the measured POF optical attenuation affects the overall performance in wavelength division multiplexing (WDM) and how use of perfluorinated polymers can overcome limitation inherent to current POF materials. Results of POF optical bandwidth measurements by direct picosecond time domain methods are reported and their relationship to refractive index profiles theoretically analyzed by the WKB and finite-element methods. Two high-resolution optical techniques of refracted near-field and transverse interferometric methods are presented and used to measure the index profiles of large core POFs. Results reveal that the index profile of current GI POF is not parabolic, but consists of two markedly different regions. Analysis of the index profile reveals that strong mode coupling increases the GI POF bandwidth from its profile-determined value of 0.43 GHz to its measured value of 3.0 GHz for 100m. We further study mode coupling effect inside POFs through various experimental techniques, including pulse broadening-length dependence measurements and far-field radiation pattern measurements.