A method for determining at least one parameter of a periodic spin function (z)
with period p, to be applied to an optical fiber along its length z during a drawing
process. At least one parameter is selected so that (I) where 1
is about 0.05 and y1 is the first of the three components y1(z),
y2(z), y3(z) of a periodic function y(z) of period p such
that (II) where LB is an expected beat length of said optical fiber
and (z) is the derivative of the spin function (z) with respect to
the length z. The method is effective for substantially reducing the PMD of optical
fibers drawn when applying a spin function.
