The invention relates to a bend-resistance multimode
optical fiber, comprising a core layer and cladding
layers. The bend-resistance multimode
optical fiber is characterized in that the
radius R1 of the core layer is 23-27 microns, the
refractive index section of the core layer is a parabola, and the cladding
layers outside the core layer successively comprise an inner cladding layer, a sunken ring, a rising ring and a sunken outer cladding layer; the thickness W2 of the single edge of the inner cladding layer is 0-2.5 microns, and the relative refractivity
delta 2 of the inner cladding layer is -0.1% to 0.1%; the thickness W3 of the single edge of the sunken ring is 0.5-6 microns, and the minimum relative refractivity
delta 3 min of the sunken ring is from -0.1% to -0.3%; the thickness W4 of the single edge of the rising ring is 0.5-10 microns, and the rising ring is a pure silica layer; the thickness W5 of the
signal edge of the sunken outer cladding layer is 17-39 microns, and the minimum relative refractivity
delta 5 min of the sunken outer cladding layer is from -0.15% to -0.6%; and delta 3 min is larger than delta 5 min. The bend-resistance multimode
optical fiber has the characteristics of extremely low
macro-bending additional attenuation, has the identical
macro-bending property at dual-communication windows (850nm and 1300nm) and
macro-bending flat feature; and the
refractive index of the sunken ring is higher than that of the sunken outer cladding layer in the optical fibre cladding layer, and the
band width of the bending-insensitive multimode optical
fiber can be effectively improved.