DEVICE FOR COUPLING TWO OPTICAL FIBERS, INTENDED TO BE USED IN CONNECTORS

Abstract

The invention relates to a new device for aligning two expanded beam optical fibers, including an alignment tube in which a relay lens is mounted. The invention is particularly intended to the integration into connectors, notably current connectors.

Claims

1. A device for aligning a first and a second optical fibers each comprising an end mounted into a ferrule, comprising: an alignment tube in which the two ferrules are mounted in an interference fit, the two ferrules being opposite and spaced with each other; an optical component that provides for both a non-physical contact and a low optical coupling loss between the first and second fibers, said component being positioned by a spacer substantially at the midpoint between the first fiber and the second fiber, such that the image of the end face of the first fiber is coincident with the end face of the second fiber.

2. A device according to claim 1 wherein the optical component is a relay lens.

3. A device according to claim 1, wherein the optical component is a graded-index (GRIN) lens.

4. A device according to claim 1, wherein the optical component is a stub terminus.

5. A device according to claim 1, wherein the tube, the spacer and the optical component are molded as a monolithic component.

6. A device according to claim 1, wherein the tube, the spacer and the optical componentare separate components assembled together.

7. A device according to claim 1, wherein the optical component is coated with one or more antireflection coatings.

8. A device according to claim 1, wherein the tube is split.

9. A single contact optical fiber connector comprising a device according to claim 1.

10. A multi-contact optical fiber connector comprising a device according to claim 1.

Description

DETAILED DESCRIPTION

[0039] Other advantages and features of the invention will become more apparent upon reading the detailed description of exemplary implementations of the invention, given as illustrative and non-limiting examples with reference to the following figures among which:

[0040] FIG. 1 is a longitudinal cross-sectional view of a first example of a device for coupling two optical fibers according to the invention;

[0041] FIG. 2 is a perspective and a longitudinal cross-sectional view of the tube and the optical component of the device according to the invention;

[0042] FIG. 3 is a longitudinal cross-sectional view of a second example of a device for coupling two optical fibers according to the invention when the optical component is molded as a monolithic component

[0043] FIG. 4 is a longitudinal cross-sectional view of a first example of a device for coupling two optical fibers according to the invention.

[0044] The device according to the invention allows to couple optically the end of two contacts comprising each a ferrule 1, 2 in which an optical fiber 3, 4 is mounted.

[0045] According to the invention, the device includes a cylindrical alignment tube 5 with an internal diameter sized to be an interference fit with the ferrules 1, 2 of the mated contacts. The tube 5 may be split so as to reduce mating friction or fabricated of a material with sufficient compliance to allow insertion of the two ferrules 1, 2.

[0046] A spacer 6 is incorporated into the tube 5 to positioning an optical component 7 at the midpoint between the first fiber 3 and the second fiber 4 such that the image of the end face of the first fiber 3 is coincident with the end face of the second fiber 4.

[0047] The focal length f of the optical component 7 is chosen such that the distance between the two focal points located at the ends of the two fibers 3, 4 allows a additional pushback of the mated contacts in order to facilitate the retrofit of fielded PC optical connectors. Typically, the distance E between the two end faces of the fibers 3, 4 is on the order of 1 mm and the additional pushback of the mated contacts is 0.5-0.6 mm each.

[0048] The optical beam exiting the first fiber 3 travels rightward towards the optical component 7 and expands to fill a solid angle equivalent to the fiber's numerical aperture. in addition to the focal length, the optical component 7 is sized such that its diameter captures all of the impinging light from the first fiber 3.

[0049] In the simplest embodiment of manufacturing, the alignment tube 5 the spacer 6, the optical component 7 may be molded as a monolithic expanded beam alignment sleeve. Furthermore, the alignment tube is not limited to the same diameter on either side of the optical element. In this way, the invention can be used as a mating adaptor allowing coupling between two dissimilar ferrule diameters.

[0050] In another embodiment, notably so as to facilitate the application of antireflection coatings on the optical surfaces of the relay lens 7, the spacer 6 and the optical component 7 can be molded as separate components, coated and then assembled into the alignment tube 5.

[0051] Other variants and enhancements can be provided without in any way departing from the framework of the invention.

[0052] By example, the refractive lens 7 shown in FIGS. 1 and 2 can be replaced by a GRIN lens 7 of a length somewhat less than the pitch condition causing the focal points to be located in space just before and after the lens surface as shown in FIG. 3. For example, E is 0.5-0.6 mm, the diameter is 1.25 mm and t is 0.04 mm.

[0053] Taking advantage of the necessary short-length of the optical element, the GRIN lens can be replaced with a stub terminus 7 featuring a graded index multimode fiber of suitable undercut to prevent physical contact of the mated. optical surfaces as shown in FIG. 4. For example, E is 1.25 mm, the diameter D is 1.25 mm and el is 0.125 mm. The space between the end face of the optical fiber and the entry of the stub terminus is not visible of the FIG. 4.

[0054] It should be understood that in both the GRIN and stub-Terminus solutions, the optical surface can be treated with an anti-reflective coating so as to prevent reflective loss at the wavelength(s) of operation.

[0055] The expression comprising a should be understood to be synonymous with comprising at least one, unless otherwise specified.

CITED REFERENCES

[0056] [1]: Hecht, Eugene (1987). Optics, 2nd ed., Addison Wesley, ISBN 0-201-11609-X. [0057] [2]: Grintech: http://www.grintech.de/gradient-index-optics.html. [0058] [3]: The Non-Contact Connector: A New Category of Optical Fiber Connector, Benjamin Ran, Arrayed Fiberoptics Corporation. OFC 2015 Proceedings.