Depressed graded index multi-mode optical fiber

A multi-mode optical waveguide fiber comprising a central core region having an outer radius ra, surrounded by an inner cladding region having an outer radius ric, said inner cladding region having a lower index of refraction than said central core region such that the fiber is depressed, wherein both the central core region and the inner cladding region are doped with fluorine, wherein the refractive index profile of the central core region is of the gradient index type and said central core region in the range of rε[0-ra] comprises germanium at a maximum concentration within the range of 0.5 percent by weight to 4.0 percent by weight taken at a given radius, wherein said fiber has an overfilled modal bandwidth >500 MHz.km at a wavelength of 850 nm and 1300 nm, according to IEC 60793-2-10, and wherein a maximum refractive index difference of the central core is substantially equal to zero.