Patent ID: 6185346
Filing Date: 2001-02-06
Classification: G02B,H04B

Abstract:
A fiber optic communication system, comprising:a multimode graded-index fiber, contained within a transmission cable of said system;light source, launching modulated light into a singlemode waveguide;first small set of lowest order propagation modes of said multimode graded-index fiber;said modulated light, propagating in said singlemode waveguide, launched into said first small set of lowest order propagation modes of said multimode graded-index fiber, by aligning said singlemode waveguide coaxially and in contact with the core of said multimode graded-index fiber;a second limited small set of lowest order propagation modes, arising from fiber bending perturbations of the lowest order fundamental mode of said multimode graded-index fiber in said transmission cable;said second limited small set of lowest order propagation modes, containing, at least, all propagation modes of said first small set of lowest order propagation modes launched into said multimode graded-index fiber;wherein said modulated light launched into said first set of modes may convert into modes of said second limited small set of lowest order propagation modes arising from fiber bending perturbations within said transmission cable;optical detector;said modulated light, propagating to the end of fiber, is detected by said optical detector;whereby said modulated light, transmitted by said multimode graded-index fiber in said transmission cable, propagates with low transmission loss, low modal noise, high data security, and high data rate capability, despite fiber bending perturbations in said transmission cable, wherein said high data rate is due to small modal time dispersion of the small number of modes in said second limited small set of lowest order propagation modes of said multimode graded-index fiber.