Patent ID: 8565568

Claim:
A multimode optical fiber, comprising: a central core surrounded by an outer cladding, said central core having (i) an outer radius r 1 of about 25±1.5 microns, (ii) an alpha-index profile, (iii) a maximum refractive index difference Δn 1 with respect to said outer cladding, and (iv) at said outer radius r 1 , a refractive index difference Δn end with respect to said outer cladding; an inner cladding positioned between said central core and said outer cladding, said inner cladding having (i) an outer radius r 2 , (ii) a width w 2 , and (iii) a refractive index difference Δn 2 with respect to said outer cladding; and a buried trench positioned between said inner cladding and said outer cladding, said buried trench having (i) an outer radius r ext , (ii) a width w 3 , (iii) a refractive index difference Δn 3 with respect to said outer cladding, and (iv) a volume v 3 ; wherein, at a wavelength of 850 nanometers, the optical fiber has an outer DMD value (0-23 microns) of less than 0.20 ps/m as measured over 750 meters of the optical fiber; and wherein said inner cladding's refractive index difference Δn 2 , said inner cladding's width w 2 , and said buried trench's refractive index difference Δn 3 satisfy the following inequalities: 1000 ×Δn 3 >A ×(1000 ×Δn 2 ) 2 +B ×(1000 ×Δn 2 )+ C ; and 1000 ×Δn 3 <D ×(1000 ×Δn 2 ) 2 +E ×(1000 ×Δn 2 )+ F; where: A=182.29×w 2 3 −550×w 2 2 +545×w 2 −177.32, B=−135.42×w 2 3 +402×w 2 2 −399×w 2 +130.22, C=15×w 2 3 −57.25×w 2 2 +60.9×w 2 −25.37, D=−83.137×w 2 3 +235.06×w 2 2 −219.52×w 2 +66.66, E=129.56×w 2 3 −388.67×w 2 2 +378.13×w 2 −121.11, and F=−48.28×w 2 3 +137.84×w 2 2 −129.9×w 2 +38.97.