Anti-PMD system

• US 7,209,604 B2
• Filed: 06/16/2004
• Issued: 04/24/2007
• Est. Priority Date: 06/24/2003
• Status: Active Grant

• Current Assignee: Draka Comteq BV (Prysmian SPA)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Dougdag, Kamel, Lainet, Eric
• Primary Examiner(s): Font; Frank G.
• Assistant Examiner(s): Hughes; James P.
• Application Number:
  US10/867,782
• Publication Number:
  US 20050018943A1
• Time in Patent Office: 1,042 Days
• Field of Search: 385/11, 385/147, 654/02
• US Class Current: 385/11
• CPC Class Codes: C03B 2203/19 Alternating positive/negative spins or twists
• CPC Class Codes: C03B 2203/36 Dispersion modified fibres, e.g. wavelength or polarisation shifted, flattened or compensating fibres (DSF, DFF, DCF)
• CPC Class Codes: C03B 2205/06 Rotating the fibre fibre about its longitudinal axis
• CPC Class Codes: C03B 37/032 for glass optical fibres

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).

Claims

1. 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 system being characterized in that the axis of rotation (ar) of the anti-PMD pulley (1) is stationary;

in that the only degree of freedom of the anti-PMD pulley (1) is rotation about the axis of rotation (ar) of the anti-PMD pulley (1); and

in that at least one of the guide devices (2, 3) is movable in translation in a translation direction (dt) that is not orthogonal to the axis of rotation (ar) of the anti-PMD pulley (1).

2. An anti-PMD system according to claim 1, characterized in that, while the optical fiber (4) is being drawn:

the guide device (2, 3) that is movable in translation angularly offsets the optical fiber (4) relative to a plane (PP) perpendicular to the axis of rotation (ar) of the anti-PMD pulley (1); and

the anti-PMD pulley (1) applies twisting torque to the optical fiber (4) alternately in the clockwise direction and in the counterclockwise direction so as to reduce the PMD of the optical fiber (4).

3. An anti-PMD system according to claim 2, characterized in that said translation direction (dt) of the guide device (2, 3) that is movable in translation lies in a plane parallel both to the axis of rotation (ar) of the anti-PMD pulley (1) and the travel direction (dd1, dd2) of the optical fiber (4) where it passes through the guide device (2, 3) while the optical fiber (4) is being drawn.

4. An anti-PMD system according to claim 3, characterized in that said translation direction (dt) is parallel to the axis of rotation (ar) of the anti-PMD pulley (1).

5. An anti-PMD system according to claim 1, characterized in that the distance between at least one point of contact between the optical fiber (4) and the guide device (2, 3) that is movable in translation, and at least one point of contact between the optical fiber (4) and the anti-PMD pulley (1) is less than or equal to the radius (R) of the anti-PMD pulley (1).

6. An anti-PMD system according to claim 5, characterized in that the distance between at least one point of contact between the optical fiber (4) and the guide device (2, 3) that is movable in translation, and at least one point of contact between the optical fiber (4) and the anti-PMD pulley (1) is less than or equal to half the radius (R) of the anti-PMD pulley (1).

7. An anti-PMD system according to claim 1, characterized in that the guide device (2, 3) that is movable in translation includes at least two guide fingers (21 &

22;

31 &

32) between which the optical fiber (4) passes while the optical fiber (4) is being drawn.

8. An anti-PMD system according to claim 7, characterized in that the guide fingers (21 &

22;

31 &

32) are movable in rotation about mutually distinct axes (23 &

24;

33 &

34).

9. An anti-PMD system according to claim 7, characterized in that the spacing between the guide fingers (21 &

22;

31 &

32) is such as to avoid damaging the covering on the optical fiber (4) while the optical fiber (4) is being drawn, and to control the angular displacement between the plane of the optical fiber (4) and the plane (PP) of the anti-PMD pulley (1).

10. An anti-PMD system according to claim 1, characterized in that the guide device (2, 3) that is movable in translation is a V-groove pulley whose axis of rotation is parallel to the axis of rotation (ar) of the anti-PMD pulley (1).

11. An anti-PMD system according to claim 1, characterized in that the movement in translation of the guide device (2, 3) that is movable in translation is slower at the ends of the stroke of said movement than in the middle of the stroke of said movement so as to impart a twist profile to the optical fiber (4) that is being drawn that is triangular rather than being sinusoidal.

12. An anti-PMD system according to claim 1, characterized in that at least the guide device (3) situated downstream from the anti-PMD pulley (1) relative to the travel direction (dd2) of the optical fiber (4) while the optical fiber (4) is being drawn is movable in translation in said translation direction (dt).

13. An anti-PMD system according to claim 12, characterized in that the anti-PMD system further comprises additional optical fiber guide means situated downstream from the downstream guide device (3) relative to the travel direction (dd2) of the optical fiber (4) while the optical fiber (4) is being drawn.

14. An anti-PMD system according to claim 1, characterized in that at least the guide device (2) situated upstream from the anti-PMD pulley (1) relative to the travel direction (dd1) of the optical fiber (4) while the optical fiber (4) is being drawn is movable in translation in said translation direction (dt), and in that the anti-PMD system further comprises additional optical fiber guide means situated upstream from the upstream guide device (2) relative to the travel direction (dd1) of the optical fiber (4) while the optical fiber (4) is being drawn.

15. An anti-PMD system according to claim 1, characterized in that both guide devices (2, 3) are movable in translation in said translation direction (dt).

16. An anti-PMD system according to claim 15, characterized in that both the two guide devices (2, 3) move in mutually opposite directions along said translation direction (dt).

17. An anti-PMD system according to claim 1, characterized in that the anti-PMD pulley (1) is a deflector pulley.

18. An anti-PMD system according to claim 1, characterized in that the anti-PMD system includes a deflector pulley, and in that the anti-PMD pulley (1) is situated downstream from the deflector pulley relative to the travel direction (dd2) of the optical fiber (4) while the optical fiber (4) is being drawn.