Optical fiber and method for making an optical fiber

1. A method of making an optical fiber, the method comprising: assembling a plurality of elongate elements to define an elongate void; using a deposition technique to form within the void a material contacting at least some of the elements while maintaining the elongate void; and drawing a preform, including the assembly of elongate elements, into an optical fiber, wherein the deposition technique is selected from the group consisting of:

forming the material in situ from a vapour or liquid phase;

forming the material with a chemical vapour deposition process;

forming the material with a thermal chemical vapour reaction;

forming the material by forming a soot and sintering the soot;

forming the material with a liquid phase deposition;

forming the material by providing a sol, allowing the sol to gel, and firing the gel; and

forming the material by providing a liquid material and setting the material.

2. The method according to claim 1 , wherein the material contacts substantially all of the elements.

3. The method according to claim 1 , wherein the material forms in crevices or gaps between adjacent elements.

4. The method according to claim 2 , wherein the material forms in crevices or gaps between adjacent elements.

5. The method according to claim 1 , wherein the material forms a layer that substantially lines the elongate void.

6. The method according to claim 1 , wherein the material substantially seals the void from other regions of the preform.

7. The method according to claim 1 , further including the step of maintaining a pressure differential between the elongate void and other regions of the preform.

8. The method according to claim 7 , wherein the pressure differential is maintained during at least a part of the drawing step.

9. The method according to claim 1 , wherein the material is formed in situ from a vapour or liquid phase.

10. The method according to claim 1 , wherein the step of forming the material comprises a chemical vapour deposition process.

11. The method according to claim 1 , wherein the material is formed by a thermal chemical vapour reaction.

12. The method according to claim 1 , wherein the step of forming the material comprises forming a soot and sintering the soot to form the material.

13. The method according to claim 12 , wherein the soot comprises silica particles.

14. The method according to claim 11 , wherein the reaction does not involve the formation of a soot.

15. The method according to any claim 1 , wherein the step of forming the material comprises a liquid phase deposition.

16. The method according to claim 1 , wherein the step of forming the material comprises providing a sol, allowing the sol to gel and firing the gel to form the material.

17. The method according to claim 16 , wherein the sol comprises a suspension of silica particles.

18. The method according to claim 1 , wherein the step of forming the material comprises providing a liquid material and setting the material.

19. The method according to claim 1 , wherein other elongate elements are arranged around the first-mentioned elongate elements.

20. The method according to claim 1 , wherein the elongate void is part of a core region of the fiber.

21. The method according to claim 1 , wherein the fiber is arranged to guide light in a hollow core defect by virtue of a photonic band-gap.