A method for manufacturing a multimode optical fiber, MMF, for a VCSEL-based communication system, the fibre having a cladding, and a core with a refractive index profile defined by n r = n 1 1 − 2 Δ r a α where: n 1 is a refractive index at a center of said core; r is the radial position inside the fiber core relative to its central axis; a is the radius of said core; α is a parameter defining a shape of the refractive index profile; Δ= ( n 1 - n 2)/ n 1; and n 2 is a refractive index of said core at r = a, said method comprising the steps of: a) obtaining at least one channel parameter associated with each of a VCSEL and said MMF; b) for a first operating wavelength, determining an α opt 1 value using said at least one parameter, where for said first operating wavelength said α opt 1 value minimizes a group delay of said MMF when said α is set equal to said α opt 1; c) for a second operating wavelength, determining an α opt 2 value using said at least one parameter, where for said second operating wavelength said α opt 2 value minimizes said group delay of said MMF when said α is set equal to said α opt 2; d) based on said α opt 1 value and said α opt 2 value, selecting an α temp value; e) for each of said first and second operating wavelengths, computing a differential mode delay, DMD, plot and a relative group delay t g by using said α temp value; f) for each of said first and second operating wavelengths, computing a modal-chromatic bandwidth by using said respective DMD plot; g) for each of said first and second operating wavelengths, calculating a maximum channel reach value by using said respective modal-chromatic bandwidth, where for said first operating wavelength said respective maximum channel reach value is R1 and for said second operating wavelength said respective maximum channel reach value is R2; h) adjusting said α temp value when R1 ≠ R2 such that α temp = α temp ± x, and repeating steps (e) - (h) wherein when R1 > R2 said α temp value is adjusted such that α temp = α temp + x, and when R1 < R2 said α temp value is adjusted such that α temp = α temp - x; i) setting said α to said α temp value when R1 = R2; and j) producing said MMF. n 1 is a refractive index at a center of said core; r is the radial position inside the fiber core relative to its central axis; a is the radius of said core; α is a parameter defining a shape of the refractive index profile; Δ= ( n 1 - n 2)/ n 1; and n 2 is a refractive index of said core at r = a, a) obtaining at least one channel parameter associated with each of a VCSEL and said MMF; b) for a first operating wavelength, determining an α opt 1 value using said at least one parameter, where for said first operating wavelength said α opt 1 value minimizes a group delay of said MMF when said α is set equal to said α opt 1; c) for a second operating wavelength, determining an α opt 2 value using said at least one parameter, where for said second operating wavelength said α opt 2 value minimizes said group delay of said MMF when said α is set equal to said α opt 2; d) based on said α opt 1 value and said α opt 2 value, selecting an α temp value; e) for each of said first and second operating wavelengths, computing a differential mode delay, DMD, plot and a relative group delay t g by using said α temp value; f) for each of said first and second operating wavelengths, computing a modal-chromatic bandwidth by using said respective DMD plot; g) for each of said first and second operating wavelengths, calculating a maximum channel reach value by using said respective modal-chromatic bandwidth, where for said first operating wavelength said respective maximum channel reach value is R1 and for said second operating wavelength said respective maximum channel reach value is R2; h) adjusting said α temp value when R1 ≠ R2 such that α temp = α temp ± x, and repeating steps (e) - (h) wherein when R1 > R2 said α temp value is adjusted such that α temp = α temp + x, and when R1 < R2 said α temp value is adjusted such that α temp = α temp - x; i) setting said α to said α temp value when R1 = R2; and j) producing said MMF.