The invention relates to a gradual
refractive index bending resistant multimode
optical fiber, which includes a sandwich layer and a cladding, and is characterized in that the
radius of the sandwich layer is 20 to 50 microns; the
refractive index of the sandwich layer is distributed in a gradient
gradation type, the distribution
power exponent Alpha is 1.89 to 1.97, and the maximum relative refringence
delta 1% max of the sandwich layer is 0.9% to 2.72%; the inner cladding is arranged adjacent to the sandwich layer, the
radius of the inner cladding is 22 to 57 microns, and the relative refringence
delta 2% is minus 0.02% to 0.02%; and a middle cladding and an outer cladding are arranged outwards the inner cladding sequentially, the middle cladding is a pure
quartz glass layer, the
radius of the middle cladding is 32 to 60 microns, the relative refringence
delta 3% is minus 0.01% to 0.01%. The gradual
refractive index bending resistant multimode
optical fiber provided by the invention not only reduces the bending dissipation of the
optical fiber, but also guarantees that optical
fiber has
high transmission bandwidth at a 1300 nm window, effectively improves the light collection and concentration capabilities of the optical
fiber to LEDs, VCSELs or LDs through increasing the core
diameter and
numerical aperture, and improves the
coupling fault-tolerant capability of luminous devices, namely between the
light source and the light transmitting device, i.e. between optical fibers.