Methods and apparatuses negate a measured mechanical twist of an optical
fiber by introducing a counteracting twist to bring the net mechanical twist closer
to zero, which reduces the fiber's polarization mode dispersion (PMD). A spool
of optical fiber having undesirable mechanical twist is mounted and fiber is drawn
from the end of the spool to impart a specified counteracting mechanical twist.
Additionally, the spool may be controllably rotated by a control system while optical
fiber is drawn there from, allowing the system to generate a precise amount of
counteracting mechanical twist in the fiber.