Bandwidth Enhancement of Step Index Plastic Optical Fibers Through a Thermal Treatment

Proper thermal treatment of large core step index plastic optical fibers resulted in a transmission bandwidth improvement of ${>}{35%}$ and optical loss decrease by approximately 7%. These improved properties remained after almost a year, with the fibers being subjected to environmental temperature variations of ${>}{\rm 30}^{\circ}{\rm C}$ over the year. The improvement of the fiber properties is attributed to the decreased accumulated modal dispersion resulting from the improved homogeneity of the PMMA material due to the thermal treatment. This interpretation has been experimentally verified. The impact of overfilled launching of light in the fiber has been examined as well.