A method of creating optical fiber to exhibit predetermined length-dependent characteristics (e.g., chromatic dispersion, polarization mode dispersion, cutoff wavelength, birefringence) includes the steps of: characterizing the fiber's selected characteristic(s) as a function of length; and performing a “treatment” which modifies the refractive index over the given length to adjust the defined parameter to fall within a defined tolerance window. These steps may be repeated one or more times until the measure of the parameter falls with the defined tolerance limits. The treatment process may include, for example, a low energy actinic radiation exposure, anneal, mechanical strain, DC voltage, plasma application, etc. Indeed, if the treatment process is repeated, a different technique may be used to adjust the refractive index (“different” processes include, for example, modifying the strength/time of a UV exposure, temperatures for annealing, etc.).