Modal dispersion and impacts of mode filtering on visible light communications over standard fibers

A theoretical study was conducted to investigate the contributions of an individual fiber mode in mode-filtering techniques for enhancing bandwidth-distance product. The study used standard single mode fiber (SMF) for visible light communication over fiber (ViLiCOF). In the worst fiber dispersion at 405nm and at 637nm wavelengths, the standard SMF supports 10 and 4 linearly polarized modes respectively. Their performances after mode filtering took place were compared and the results reveal that; without accounting attenuation caused by Rayleigh scattering and Urbach tail effects, the small discrepancies between modal group indices of fundamental and slowest modes are very sensitive to the fiber bandwidth-distance product. In addition, the results of this study support the previous idea of mode filtering techniques as the methods for enhancing fiber bandwidth product; however, the evidence from this study suggests that fiber mode with the largest modal group indices should be targeted as their presence contributes the maximum modal delay. Furthermore, the results show the possibility of extending bandwidth of standard SMF to include visible light spectrum.