Optimization of the Refractive-Index Distribution of High-Bandwidth GI Polymer Optical Fiber Based on Both Modal and Material Dispersions

Abstract

ABSTRACT:The optimum refractive-index distribution of the high bandwidth graded-index polymer optical fiber (GI POF) in which material dispersion is taken into account was clarified for the first time. Since modal dispersion remarkably decreases by GI POF, this paper focuses on the ultimate bandwidth achieved by POF, quantitatively estimating the material dispersion as well as modal dispersion. The results indicated that the bandwidth of the poly(methyl methacrylate) (PMMA) based GI POF was dominated by material dispersion when the required data rate becomes larger than a few Gb s-1 • It was also confirmed that material dispersion strongly depends on the matrix polymer and that use of fluorinated polymer whose material dispersion (-0.078 nsnm-1 km-1 ) is lower than that ofPMMA (-0.305nsnm-1 km-1 ) allows for a lOGbs-1 signal transmission.KEY WORDS Polymer Optical Fiber I Graded-Index

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“…The GI profile of the fiber in the core region is usually approximately determined by the power law equation16–21: where n 1 and n 2 are the refractive indices of the core center and the cladding, respectively, a the core radius, and g the index exponent. The Δ and g values are very important because they are directly related to the transmission speed.…”

“…The Δ and g values are very important because they are directly related to the transmission speed. The transmission speed is highest when g is about 2 and Δ is 0.01–0.02 16–21. To evaluate Δ and g of the core part, we plotted log{1−[ n ( r ) 2 / n 1 2 ]} with log ( r / a ).…”

Fabrication of a gradient refractive index preform using laminar shear mixing

“…Generally, the GI profile of the preform (core part) can be written as12 Here r is the radial distance from the center of the preform, R is the radius of the preform, n 0 is the refractive index at the center of the preform, and n 1 is the refractive index at the periphery of the perform, and the dimensionless parameter g is defined as the index profile shape. The index difference (Δ) is defined as The transmission speed is highest when g is about 2 and Δ is 0.01 to 0.02 if there is no material dispersion 12–15. To evaluate Δ and g of the core part, we plotted log{1 − [ n ( r ) 2 / n 0 2 ]} with log ( r / R ) after we rescaled r / R = 0.65 (end of core part) to 1, as shown in the inset of Figure 4.…”

Fabrication of refractive index distributions in polymer using a photochemical reaction

“…where r is the radial distance from the center axis, n 0 is the refractive index at the center, a is the coefficient, and g is the index exponent. For GI optical fibers with minimum mordal dispersion, a value g in the range of 1.9-2.4 21,22 is required. This result indicates that the refractive index profile control method investigated in this work can give an appropriate profile for GI-POF.…”