Optical connector and connection structure of optical fibers

Abstract

An optical connector having: a ferrule into which a first optical fiber is inserted; an optical fiber connector disposed at an back end of the ferrule; and a cross-linkable refractive index matching member attached onto an end face on a back end side of the first optical fiber. The end face on the back end side of the first optical fiber and an end face of a second optical fiber to be inserted into the optical fiber connector from a back end side thereof are to be connected by a butting connection. The cross-linkable refractive index matching member is formed such that a cross-linkable refractive index matching agent is coated on the end face on the back end side of the first optical fiber, and the coated agent is cross-linked and hardened.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments according to the invention will be explained below referring to the drawings, wherein:

FIG. 1 is a cross sectional view showing an optical connector (after a butting connection of optical fibers) in a preferred embodiment according to the invention;

FIG. 2 is a side view showing an example of an optical fiber to be housed in an optical connector in a preferred embodiment according to the invention;

FIG. 3A is a side view showing an example of an optical fiber being attached with a cross-linkable refractive index matching member at the end face thereof, to be housed in an optical connector in a preferred embodiment (Examples 1 and 2) according to the invention (a partially enlarged view showing an end portion of the optical fiber shown in FIG. 2);

FIG. 3B is a side view showing an example of an optical fiber being attached with a cross-linkable refractive index matching member at the end face thereof, to be housed in an optical connector in a preferred embodiment (Examples 3 and 4) according to the invention (a partially enlarged view showing an end portion of the optical fiber shown in FIG. 2);

FIG. 4 is a cross sectional view showing an optical connector (before an insertion of a wedge to a wedge insertion groove) in a preferred embodiment according to the invention;

FIG. 5 is a side view showing an optical connector (after an insertion of a wedge to a wedge insertion groove) in a preferred embodiment according to the invention;

FIG. 6A is a cross sectional view showing an optical connector (before an insertion of a wedge to a wedge insertion groove) in a preferred embodiment according to the invention (a cross sectional view taken along the line A-A in FIG. 4);

FIG. 6B is a cross sectional view showing an optical connector (after an insertion of a wedge to a wedge insertion groove) in a preferred embodiment according to the invention (a cross sectional view taken along the line B-B in FIG. 5);

FIG. 7 is a cross sectional view showing an optical connector (after an insertion of a wedge to a wedge insertion groove) in a preferred embodiment according to the invention;

FIG. 8 is a cross sectional view showing an example of a second optical fiber to be inserted to an optical connector in a preferred embodiment according to the invention and an optical connector in Comparative Example;

FIG. 9 is a graph showing a temperature condition (a relation between a temperature and an elapsed time) in a test (a continuous temperature and humidity cycle test) conducted by using an optical connector in a preferred embodiment according to the invention and an optical connector in Comparative Example;

FIG. 10 is a graph showing a temperature condition (a relation between a temperature and an elapsed time) in a test (a temperature cycle test) conducted by using an optical connector in a preferred embodiment according to the invention and an optical connector in Comparative Example;

FIG. 11 is a graph showing a temperature condition (a relation between a temperature and an elapsed time) in a test (a temperature and humidity cycle test) conducted by using an optical connector in a preferred embodiment according to the invention and an optical connector in Comparative Example;

FIG. 12 is a graph showing a temperature condition (a relation between a temperature and an elapsed time) in a test (a low temperature test) conducted by using an optical connector in a preferred embodiment according to the invention and an optical connector in Comparative Example;

FIG. 13 is a graph showing a relation between a thickness (μm) of the cross-linkable refractive index matching member and an increase of loss (dB) measured in the temperature cycle test while a thickness of the cross-linkable refractive index matching member is changed, the member attached to the end surface in back-end side of the first optical fiber in the first preferred embodiment (Examples 1, 2) according to the invention; and

FIG. 14 is a graph showing a relation between a thickness (μm) of the cross-linkable refractive index matching member and an increase of loss (dB) measured in the temperature cycle test while a thickness of the cross-linkable refractive index matching member is changed, the member attached to the end surface in back-end side of the first optical fiber in the first preferred embodiment (Examples 3, 4) according to the invention.

Claims

1. An optical connector comprising: a ferrule into which a first optical fiber is inserted;an optical fiber connector disposed at an back end of the ferrule; anda cross-linkable refractive index matching member attached onto an end face on a back end side of the first optical fiber,wherein the end face on the back end side of the first optical fiber and an end face of a second optical fiber to be inserted into the optical fiber connector from a back end side thereof are to be connected by a butting connection, andthe cross-linkable refractive index matching member is formed such that a cross-linkable refractive index matching agent is coated on the end face on the back end side of the first optical fiber, and the coated agent is cross-linked and hardened.

2. The optical connector according to claim 1, wherein: the end face on the back end side of the first optical fiber is formed spherical.

3. The optical connector according to claim 1, wherein: the cross-linkable refractive index matching member comprises a refractive index within 1.46±0.05.

4. The optical connector according to claim 1, wherein: the cross-linkable refractive index matching member comprises a rate of change in refractive index within ±2% at a temperature of −40 to 70° C.

5. The optical connector according to claim 1, wherein: the cross-linkable refractive index matching member comprises an optical transmittance of 80% or more.

6. The optical connector according to claim 1, wherein: the cross-linkable refractive index matching member comprises a breaking elongation of 50% or more.

7. The optical connector according to claim 1, wherein: the cross-linkable refractive index matching member comprises a glass adhesive force of 50 g/10 mm width or more.

8. The optical connector according to claim 1, wherein: the cross-linkable refractive index matching member comprises a thickness of 5 to 100 μm.

9. The optical connector according to claim 1, wherein: a face of the cross-linkable refractive index matching member to contact the end face of the second optical fiber to be inserted into the optical fiber connector from the back end side thereof is formed spherical.

10. The optical connector according to claim 1, wherein: the cross-linkable refractive index matching member is attached to only the end face of the first optical fiber.

11. The optical connector according to claim 1, wherein: the cross-linkable refractive index matching member is attached ranging from the end face to a side face of the first optical fiber.

12. The optical connector according to claim 2, wherein: the spherical form of the end face on the back end side of the first optical fiber comprises a curvature radius of 0.1 to 30 mm.

13. The optical connector according to claim 1, wherein: the optical fiber connector comprises a plate comprising a groove with a cross-sectional area greater than the second optical fiber to be inserted from the back end side thereof.

14. The optical connector according to claim 13, wherein: the groove comprises a V-shaped groove.

15. The optical connector according to claim 1, wherein: the second optical fiber comprises a holey fiber.

16. A connection structure of optical fibers comprising: a first optical fiber;a ferrule into which the first optical fiber is inserted;an optical fiber connector disposed at a back end of the ferrule;a second optical fiber inserted into the optical fiber connector from a back end side thereof; anda cross-linkable refractive index matching member attached onto an end face on a back end side of the first optical fiber,wherein the end face on the back end side of the first optical fiber and an end face of a second optical fiber are connected by a butting connection, andthe cross-linkable refractive index matching member is formed such that a cross-linkable refractive index matching agent is coated on the end face on the back end side of the first optical fiber, and the coated agent is cross-linked and hardened.

17. The connection structure according to claim 16, wherein: the end face on the back end side of the first optical fiber is formed spherical.

18. The connection structure according to claim 16, wherein: the cross-linkable refractive index matching member comprises a refractive index within 1.46±0.05.

19. The connection structure according to claim 16, wherein: the cross-linkable refractive index matching member comprises a rate of change in refractive index within ±2% at a temperature of −40 to 70° C.

20. The connection structure according to claim 16, wherein: the cross-linkable refractive index matching member comprises an optical transmittance of 80% or more.

21. The connection structure according to claim 16, wherein: the cross-linkable refractive index matching member comprises a breaking elongation of 50% or more.

22. The connection structure according to claim 16, wherein: the cross-linkable refractive index matching member comprises a glass adhesive force of 50 g/10 mm width or more.

23. The connection structure according to claim 16, wherein: the cross-linkable refractive index matching member comprises a thickness of 5 to 100 μm.

24. The connection structure according to claim 16, wherein: a face of the cross-linkable refractive index matching member in contact with the end face of the second optical fiber by being inserted into the optical fiber connector from the back end side thereof is formed spherical.

25. The connection structure according to claim 16, wherein: the cross-linkable refractive index matching member is attached onto only the end face of the first optical fiber.

26. The connection structure according to claim 16, wherein: the cross-linkable refractive index matching member is attached ranging from the end face to a side face of the first optical fiber.

27. The connection structure according to claim 17, wherein: the spherical form of the end face on the back end side of the first optical fiber comprises a curvature radius of 0.1 to 30 mm.

28. The connection structure according to claim 16, wherein: the optical fiber connector comprises a plate comprising a groove with a cross-sectional area greater than the second optical fiber inserted from the back end side thereof.

29. The connection structure according to claim 28, wherein: the groove comprises a V-shaped groove.

30. The connection structure according to claim 16, wherein: the second optical fiber comprises a holey fiber.