Large numerical aperture bend resistant multimode optical fiber

A bend-resistant optical fiber which is multi-moded at 1300 nm comprising a core, an inner cladding, a low index ring, and an outer cladding, wherein:

• the core is formed from silica-based glass and comprises a graded index of refraction with a core alpha profile where 1.9≦αC≦2.1, a maximum relative refractive index percent Δ1Max% relative to pure silica glass, and a numerical aperture NA of greater than 0.23;
• the inner cladding surrounds and is in direct contact with the core, the inner cladding having a graded index of refraction with an inner cladding alpha profile αIC, a maximum relative refractive index percent Δ2Max% relative to pure silica glass, and a minimum relative refractive index percent Δ2Min% relative to pure silica glass, wherein Δ1Max%>Δ2Max%;
• the low index ring surrounds and is in direct contact with the extended core region such that the low index ring is spaced apart from the core, the low index ring having a relative refractive index percent Δ3% relative to pure silica glass, a radial thickness of at least 1 micron and a profile volume with an absolute magnitude of greater than 50%-μm2, wherein Δ2Min%≧Δ3%;
• the outer cladding surrounds and is in direct contact with the low index ring, the outer cladding comprising a relative refractive index percent Δ4% relative to pure silica glass, wherein Δ1Max%>Δ4%≧Δ2Max%.

A bend resistant optical fiber which is multi-moded at 1300 nm comprising a core, an inner cladding, a low index ring and an outer cladding, wherein:

• the core is formed from silica-based glass and comprises a graded index of refraction with a core alpha profile where 1.9≦αC≦2.1, a maximum relative refractive index percent Δ1Max% relative to pure silica glass, and a numerical aperture NA of greater than 0.23;
• the inner cladding surrounds and is in direct contact with the core, the inner cladding having a maximum relative refractive index percent Δ2Max% relative to pure silica glass, a minimum relative refractive index percent Δ2Min% relative to pure silica glass, a radial thickness of at least 0.5 microns, wherein Δ2Max%−Δ2Min≦0.1% and Δ1Max%>Δ2Max%;
• the low index ring that surrounds and is in direct contact with the inner cladding such that the low index ring is spaced apart from the core, the low index ring having a relative refractive index percent Δ3% relative to pure silica glass, a radial thickness of at least 0.5 microns and a profile volume with an absolute magnitude of greater than 50%-μm2, wherein the minimum relative refractive index percent Δ2Min% of the inner cladding is greater than or equal to Δ3%;
• and
• the outer cladding surrounds and is in direct contact with the low index ring, the outer cladding comprising a relative refractive index percent Δ4% relative to pure silica glass, wherein Δ1Max%>Δ4%≧Δ2Max%.