Abstract: An anti-PMD system comprises a pulley which oscillates in rotation and applies a torsion torque alternately in the clockwise direction and in the counterclockwise direction to an optical fiber during drawing of the optical fiber to reduce its PMD. A portion of a peripheral external surface of the pulley intended to be in contact with the optical fiber during drawing is convex.

Abstract: An optical fiber drawing installation is equipped with an oscillating pulley that applies torsion to the fiber alternately in one rotation direction and then in the opposite direction. To control the torsion applied to the fiber, images are formed of the fiber and the pulley. The images are analyzed to determine the position of the fiber relative to the pulley. The torsion is calculated from the calculated position, on the assumption that the fiber rolls on the pulley.

Abstract: The invention provides an anti-PMD system comprising: an anti-PMD pulley (1) over which an optical fiber (4) is to roll and which is mounted to rotate about an axis of rotation (ar); and at least two optical fiber guide devices (2, 3) situated on either side of the anti-PMD pulley (1); the axis of rotation (ar) of the anti-PMD pulley (1) being stationary; the only degree of freedom of the anti-PMD pulley (1) being rotation about the axis of rotation (ar) of the anti-PMD pulley (1); and at least one of the guide devices (2, 3) being movable in translation in a translation direction (dt) that is not orthogonal to the axis of rotation (ar) of the anti-PMD pulley (1).

Abstract: The invention provides an anti-PMD system comprising: an anti-PMD pulley (1) over which an optical fiber (4) is to roll and which is mounted to rotate about an axis of rotation (ar); and at least two optical fiber guide devices (2, 3) situated on either side of the anti-PMD pulley (1); the axis of rotation (ar) of the anti-PMD pulley (1) being stationary; the only degree of freedom of the anti-PMD pulley (1) being rotation about the axis of rotation (ar) of the anti-PMD pulley (1); and at least one of the guide devices (2, 3) being movable in translation in a translation direction (dt) that is not orthogonal to the axis of rotation (ar) of the anti-PMD pulley (1).

Abstract: An optical fiber drawing installation is equipped with an oscillating pulley that applies torsion to the fiber alternately in one rotation direction and then in the opposite direction. To control the torsion applied to the fiber, images are formed of the fiber and the pulley. The images are analyzed to determine the position of the fiber relative to the pulley. The torsion is calculated from the calculated position, on the assumption that the fiber rolls on the pulley.

Abstract: An anti-PMD system comprises a pulley which oscillates in rotation and applies a torsion torque alternately in the clockwise direction and in the counterclockwise direction to an optical fiber during drawing of the optical fiber to reduce its PMD. A portion of a peripheral external surface of the pulley intended to be in contact with the optical fiber during drawing is convex.

Abstract: A method of cooling an optical fiber while it is being drawn through contact with at least one cooling fluid in at least one cooling area, wherein said method is such that fast cooling, i.e. cooling that is faster than cooling in the surrounding air, is followed by slow cooling, i.e. cooling slower than cooling in the surrounding air, the temperature of the fiber in an intermediate area between the two cooling areas lying in the range 1200° C. to 1700° C. in the case of silica glass fibers.

Abstract: The method consists of increasing the flowrate of argon injected into the bottom of a fiber-drawing furnace when a weld between two sections of a preform is being drawn during the operation of drawing a fiber from a preform. This prevents the weld causing an excessive increase in the diameter of the resulting fiber and/or an excessive variation in the drawing speed.

Abstract: A method of cooling an optical fiber while it is being drawn through contact with at least one cooling fluid in at least one cooling area, wherein said method is such that fast cooling, i.e. cooling that is faster than cooling in the surrounding air, is followed by slow cooling, i.e. cooling slower than cooling in the surrounding air, the temperature of the fiber in an intermediate area between the two cooling areas lying in the range 1200° C. to 1700° C. in the case of silica glass fibers.