Method of manufacturing an optical fiber using axial tension control to reduce axial variations in optical properties

A method of manufacturing a tuned optical fiber, comprising:

• providing in a furnace a first preform from a set of preforms, each preform in the set of preforms having an axial variation in soot overclad thickness, the axial variation in soot overclad thickness leading to a variation in a cable cut-off wavelength λC of the preform as a function of axial position relative to a target value of the cable cut-off wavelength λC;
• drawing a reference optical fiber from the first preform using a constant draw tension;
• determining a variation in the cable cut-off wavelength λC of the reference optical fiber as a function of axial position relative to the target value of the cable cut-off wavelength λC;
• and
• drawing from a second preform from the set of preforms a tuned optical fiber, the drawing from the second preform including using a time-varying draw tension, the time-varying draw tension reducing the variation in the cable cut-off wavelength λC as a function of axial position relative to the target value in the tuned optical fiber to less than the variation in the cable cut-off wavelength λC as a function of axial position relative to the target value in the reference optical fiber;
• wherein the cable cut-off wavelength of the tuned optical fiber varies by no more than 10 nm from a mean value of the cable cut-off wavelength for a length of the tuned optical fiber of at least 5 kilometers;
• and
• wherein the time-varying draw tension is either within a first draw-tension regime where the cable cut-off wavelength λC decreases with increasing draw tension or within a second draw-tension regime where the cable cut-off wavelength λC increases with increasing draw tension, the first draw-tension regime comprising a draw tension in the range from about 70 grams (g) to about 120 g and the second draw-tension region comprising a draw tension in the range from about 125 g to about 200 g.