Photochromic optical waveguides and method for the preparation thereof

1. An optical waveguide comprising a matrix and an optical path including a photochromic diarylethene polymer having the general formula (Ia)

wherein

X is S, O, Se, Te, or N—R, wherein R is hydrogen or a linear or branched (C 1-12 )alkyl group;

R 1 is hydrogen, a linear or branched (C 1-12 )alkyl or (C 1-12 )alkoxy group;

R 2 is a linear or branched (C 1-12 )alkyl group; and

m=4–100.

2. The optical waveguide according to claim 1 , wherein X is S, Se or Te.

3. The optical waveguide according to claim 2 , wherein X is S.

4. The optical waveguide according to claim 1 , wherein R 1 is hydrogen or a (C 1-3 )alkyl group.

5. The optical waveguide according to claim 1 , wherein the optical path is surrounded by a matrix comprising a photochromic diarylethene polymer having the general formula (Ib)

wherein

X is S, O, Se, Te, or N—R, wherein R is hydrogen or a linear or branched (C 1-12 )alkyl group;

R 1 is hydrogen, a linear or branched (C 1-12 )alkyl or (C 1-12 )alkoxy group;

R 2 is a linear or branched (C 1-12 )alkyl group; and

m=4–100.

6. The optical waveguide according to claim 5 , wherein X is S, Se or Te.

7. The optical waveguide according to claim 6 , wherein X is S.

8. The optical waveguide according to claim 5 , wherein R 1 is hydrogen or a (C 1-3 )alkyl group.

9. The optical waveguide according to claim 1 , wherein said photochromic diarylethene polymer is dispersed in said matrix.

10. The optical waveguide according to claim 1 , wherein said matrix is selected from polystyrene, polymethylmethacrylate (PMMA), polycarbonate, polysulphone, polyimide, fluorinated or deuterated PMMA, and mixtures thereof.

11. A method for the preparation of an optical waveguide comprising the steps of:

a) dissolving in an organic solvent a photochromic diarylethene polymer having formula (1b)

b) mixing the thus obtained solution and a polymeric matrix until a dispersion is obtained;

c) preparing a film by depositing said dispersion on a substrate; and

d) irradiating said film so as to form an optical path comprising a photochromic diarylethene polymer having formula (Ia)

wherein in formula (1b) and (1a)

X is S, O, Se, Te, or N—R, wherein R is hydrogen or a linear or branched (C 1-12 )alkyl group;

R 1 is hydrogen, a linear or branched (C 1-12 )alkyl or (C 1-12 )alkoxy group;

R 2 is a linear or branched (C 1-12 )alkyl group; and

m=4–100.

12. The method according to claim 11 , wherein X is S, Se or Te.

13. The method according to claim 12 , wherein X is S.

14. The method according to claim 11 , wherein R 1 is hydrogen or a (C 1-3 )alkyl group.

15. The method according to claim 11 , wherein the organic solvent is a chlorinated solvent.

16. The method according to claim 11 , wherein the photochromic diarylethene polymer of the invention is dissolved in said matrix at a concentration not higher than 20% by weight.

17. The method according to claim 16 , wherein said concentration is between 0.1% and 15% by weight.

18. The method according to claim 17 , wherein the concentration is between about 5 and about 10% by weight.