Patent ID: 8737791

Claim:
A multi-mode optical fiber having a center and comprising the following sequential concentric regions extending radially outward from the center: an alpha core region having an essentially alpha profile extending radially from the center of the optical fiber to a distance R1, with an index n 1 at the core center, the alpha core region has n ( r )=[ n 1 2 −( n 1 2 −n clad 2 )( r/R 2) α ] 1/2 , where r is the radius of the fiber, n 1 is the refractive index at center of core, R2 is the radius of the core, n clad is the refractive index of the cladding, and α is a free parameter whose value is in the range 1.7 to 2.2; an index step at R1 defined by a refractive index difference n s −n clad , wherein n s is the refractive index at R1 and n clad is the refractive index of an inner cladding region extending radially outward from R1 for a distance greater than 0.5 microns, a trench region extending radially from inner cladding, and an outer cladding region extending radially outward from the trench region.