Propagation in lowest order modes of multimode graded index fiber, resulting in: very low transmission loss, low modal noise, high data security, and high data rate capabilities

摘要

This invention relates to optical fiber communication systems where data light is launched into a very small set of the lowest order propagation modes of multimode graded-index fibers, resulting in very high data rate transmission capability. We have determined, experimentally and theoretically, that light launched into a small set of a few lowest order propagation modes, or launched only into the fundamental propagation mode of multimode graded-index fiber, converts into and within a limited small set of lowest order modes due to severe bending perturbations that may occur in deployed multimode graded-index fiber transmission cable. Low modal time dispersion of the limited small set of lowest order modes is much less than when all modes of the multimode graded-index fiber are launched, yielding a much higher data rate transmission capability. Added advantages are: low transmission loss, low modal noise, and data security. Methods for launching the small set of lowest order propagation modes or the fundamental propagation modes into a single multimode graded-index fiber or into a plurality of multimode fibers in other optical fiber communication networks are described.