Patent ID: 8588568

Claim:
A graded index multimode optical fiber comprising: (a) a core comprising silica doped with germania and at least one co-dopant, c-d, the co-dopant comprising one of P 2 O 5 or F or B 2 O 3 , the core extending from a centerline at r=0 to an outermost core radius, r 1 and having a dual alpha, α 1 and α; (b) an inner cladding surrounding and in contact with the core; (c) an outer cladding surrounding and in contact with the inner cladding, at least one region of the inner cladding having a lower refractive index than the outer cladding and being off-set from said core; and the germania is disposed in the core with a germania dopant concentration profile, C Ge1 (r), and the core has a center germania concentration at the centerline, C Ge1 , greater than or equal to 0, and an outermost germania concentration C Ge2 , at r 1 , wherein C Ge2 , is greater than or equal to 0; and wherein the co-dopant is disposed in the core with a co-dopant concentration profile, C c-d (r), and the core has a center co-dopant concentration at the centerline, C c-d1 , greater than or equal to 0, and an outermost co-dopant concentration C c-d2 , at r 1 , wherein C c-d2 is greater than or equal to 0; and C Ge (r)=C Ge1 −(C Ge1 −C Ge2 )(1−x 1 )r α1 −(C Ge1 −C Ge2 )x 1 r α2 ; C c-d (r)=C c-d1 −(C c-d1 −C c-d2 )x 2 r α1 −(C c-d1 −C c-d2 )(1−x 2 )r 2 ; 1.8< 1 <2.4, 1.8<α 2 <3.1; and −10<x 1 <10 and −10<x 2 <10.