Multi-mode bending-resistant fiber and production method thereof

Abstract

A multimode fiber including a core and a cladding. The core has a radius (R) of 24-26 μm, the refractive index profile thereof is a parabola, and the maximum relative refractive index difference (Δ1) is 0.9-1.1%. The cladding surrounds the core and includes from inside to outside an inner cladding, a middle cladding, and an outer cladding; a radius (R) of the inner cladding is 1.04-1.6 times that of the core, and a relative refractive index difference (Δ2) thereof is −0.01-0.01%; the middle cladding is a graded refractive index cladding whose radius (R) is 1.06-1.8 times that of the core, and a relative refractive index difference thereof is decreased from Δ2 to Δ4; and a radius (R) of the outer cladding is 2.38-2.63 times that of the core, and a relative refractive index difference (Δ4) thereof is between −0.20 and −0.40%. The invention reduces the additional bending loss of the fiber, improves the bending resistance and mechanical properties, basically eliminates the internal stress, and ensures the service life even working for a long term under the condition of low radius. The method for producing the fiber is simple, effective, and suitable for mass production.