Abstract: In a process for producing a low polarization mode dispersion optical fiber, which comprises the steps of drawing a glass preform into an optical fiber and of spinning, during drawing, the optical fiber about an optical fiber axis, the spinning is imparted according to a bidirectional and substantially trapezoidal spin function, which includes zones (P) of substantially constant amplitude (plateau) and zones of transition (T) where inversion of the spin direction takes place, wherein the extension (p) of the zones of substantially constant amplitude is greater than the extension (t) of the zones of transition, and the number of inversions of the direction of spin in a length of fiber of 20 m is at most two.

Abstract: The hydroxyl content in an optical fiber is stabilized by a manufacturing process involving exposure of the optical fiber to a mixture of deuterium and a predetermined amount of hydrogen.

Abstract: A method and apparatus for manufacturing an optical fiber includes the steps and/or means of: drawing a fiber from a heated preform by applying a pulling force to the fiber; spinning the fiber while it is drawn, wherein the step of spinning the fiber includes the sub-steps of winding the fiber on a spin roller by a winding arc, such that a friction force is generated between the fiber and the spin roller resulting from the winding arc and from the pulling force; axially displacing the spin roller such that the fiber is caused to roll over the spin roller surface by the friction force.

Abstract: In a process for producing a low polarization mode dispersion optical fiber, which comprises the steps of drawing a glass preform into an optical fiber and of spinning, during drawing, the optical fiber about an optical fiber axis, the spinning is imparted according to a bidirectional and substantially trapezoidal spin function, which includes zones (P) of substantially constant amplitude (plateau) and zones of transition (T) where inversion of the spin direction takes place, wherein the extension (p) of the zones of substantially constant amplitude is greater than the extension (t) of the zones of transition, and the number of inversions of the direction of spin in a length of fiber of 20 m is at most two.

Abstract: The present invention relates to a method and apparatus for cooling an optical fiber during the drawing process of said fiber. In particular the present method for cooling an optical fiber comprises flowing a cooling gas onto the optical fiber wherein the flow direction of the cooling gas is substantially transversal with respect the longitudinal axis of the fiber. It has been found that by employing a flow of cooling gas being substantially transversal to the longitudinal axis of the drawn fiber, the cooling efficiency of the fiber may be substantially improved.

Abstract: An optical fibre tensioning device, receiving at its input an optical fibre from a traction device and capable of supplying the optical fibre from its output to a device for storing the fibre. The tensioning device comprises at least one fixed pulley on which the optical fibre is wound for a first length, and at least one movable pulley on which the optical fibre is wound for a second length. A device for measuring the tension applied to the fibre and a motorized device for moving the movable pulley interact with each other to control a distance (Dp) between axes of the pulleys in such a way as to automatically keep the tension applied to the fibre essentially constant.

Abstract: A method for manufacturing an optical fiber (100) having low PMD, comprises the steps of: a) heating at least one end portion (3a) of a preform (3); b) drawing an optical fiber (100) from a free end of said heated end portion (3a) along a fiber drawing axis (I—I); c) coating said optical fiber (100) with a suitable coating material; d) applying to said coated optical fiber (100) a torque about said fiber drawing axis (I—I), e) winding said coated optical fiber (100) onto a collecting spool (9). According to the invention, step d) is carried out by means of a pulley (16) supported upstream of said collecting spool (9) and rotated about the fiber drawing axis (I—I), said optical fiber (100) being wound up onto said pulley (16) for an angle of at least about 360°. Advantageously, such method also allows to notably increase the amount of optical fiber produced per unit of time with respect to the prior art.

Abstract: Optical fiber tensioning device, receiving at its input an optical fiber (35) from a traction device (37) and capable of supplying the optical fiber from its output to a device (40) for storing the fiber. The tensioning device (1) comprises at least one fixed pulley (32) on which the optical fiber (35) is wound, for a certain length at least, and at least one movable pulley (9) on which the optical fiber (35) is wound, for a certain length at least. A device for measuring the tension applied to the fiber and a motorized device (24, 26, 5, 7) for moving the movable pulley (9) interact with each other to control the distance (Dp) between the axes (33, 20) of the pulleys (32, 9) in such a way as to automatically keep the tension applied to the fiber essentially constant.