JPS6158806B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an optical fiber connector, and particularly to an optical fiber connector that prevents reflection without impairing connection loss.

(2) Background of the Technology Figure 1 is a diagram for explaining a conventional optical fiber connector. In the figure, 1 and 1' are optical fiber cables, 2 and 2' are optical fibers, 3 and 3' are ferrules for aligning and fixing the optical fibers, and 4
denotes an alignment sleeve member, and 5 and 5' denote cap nuts, respectively.

As shown in FIG. 1, the ferrules 3 and 3' align and fix the optical fibers 2 and 2', respectively, and are inserted into the alignment sleeve member 4 and removably fixed by cap nuts 5 and 5'.

Conventionally, such optical fiber connectors have been designed to reduce light transmission loss by eliminating eccentricity of the opposing optical fibers and angular deviation of the end faces as much as possible, but between the end faces of the optical fibers 2 and 2' Since there is always an air layer in the surface, there is always a reflective area due to the difference in refractive index. Although the reflection from this reflection part appears to be small, it cannot be ignored if the overall loss in the connector is reduced, and the influence of multiple reflections becomes particularly large.

FIG. 2 is a diagram showing multiple reflections at the end face of an optical fiber. In the figure, 2 and 2' are optical fibers, A is passing light, and B and C are multiple reflected lights.

In this case, depending on the relationship between the gap G between the optical fiber end faces and the wavelength of the light, the multiple reflected light may interfere and be amplified or attenuated, and the fluctuation range of the level is about 0.5 dB. . Therefore, if the connector loss is 0.5dB, the loss is 0.25dB to 0.75dB.
It will fluctuate within a range of Further, the return reflection B becomes noise in the case of two-way communication and has an adverse effect on the receiving side.

(3) Prior Art and Problems Conventional antireflection structures include a method in which a matching agent is filled into the gap between the end faces of optical fibers, and a method in which the end faces of the optical fibers are polished obliquely.

However, since liquid or synthetic resin is used as a matching agent, it has been difficult to obtain reliability as an optical connector against dirt, surface abrasion, environmental resistance, etc. during repeated attachment and detachment. Regarding this, as shown in Fig. 3, the end faces of the optical fibers 2 and 2' are polished parallel and obliquely, and the returning reflected light B is set at a critical angle or more and escapes toward the cladding, eliminating its influence. Regarding multiple reflection C, it is the same as in the case of FIG. 2 and has not been improved.

For this purpose, the tip of the ferrule is polished obliquely along with the optical fiber, and the central axes of the slanted surfaces are rotated by a certain angle in opposite directions to create a wedge-shaped gap for multiple reflections. One possible method is to average out the interference. However, in this case, there is a drawback that the distance between the end faces of the optical fibers becomes large and the connection loss increases.

(4) Purpose of the Invention In view of the above-mentioned conventional drawbacks, the object of the present invention is to provide an optical fiber connector that prevents reflection while maintaining stable connection loss characteristics without using auxiliary materials such as matching agents. It is.

(5) Structure of the Invention According to the present invention, this object is to align and fix the optical fibers 8, divide the tip end surface into two by a straight line close to the optical fiber, and make the surface containing the optical fiber 8 an inclined surface. In an optical fiber connector comprising a pair of ferrules 6 and an alignment sleeve member 13 that supports the pair of ferrules by butting their tips, when the pair of ferrules 6 are butted together. , the ferrules 6, 6' and the alignment sleeve member 13 so that the ridge lines of their tip surfaces are non-parallel to each other.
This is achieved by providing an optical fiber connector characterized in that it is provided with positioning means.

(6) Embodiments of the Invention FIG. 4 is a diagram showing a ferrule of an optical fiber connector according to the present invention, in which a shows a longitudinal sectional view and b shows a side view.

In the figure, 6 indicates a ferrule, 7 indicates an optical fiber cable, 8 indicates the optical fiber, and 9 indicates a positioning key. The tip 10 of the ferrule 6 has a surface 11 perpendicular to the optical axis of the optical fiber proximate to the optical fiber 8 and is divided into two by a line as shown in Figure A.
The side that includes the optical fiber 8 is the optical fiber 8
In addition, the central axis 12 of this polished surface is rotated by α° with respect to the positioning key 9, as shown in figure b.

FIG. 5 is a diagram showing an alignment sleeve member of an optical fiber connector according to the present invention, in which a is a longitudinal sectional view;
b shows a view in the direction of the Y arrow in figure a, and c shows a view in the direction of the Z arrow in figure a.

In the figure, 13 is an alignment sleeve member; 14 is an alignment sleeve member;
is a sleeve portion that holds the ferrules in alignment, 15
and 16 are positioning grooves for positioning the ferrule, and 17 and 18 are screws screwed into cap nuts for fixing the ferrule. Note that the positioning grooves 15 and 16 are formed at positions 180 degrees apart from each other as shown in the figure.

Each member thus formed is assembled as shown in FIG. In the same figure, 6 is a ferrule,
Reference numeral 13 indicates an alignment sleeve member, and 19 and 20 indicate cap nuts, respectively. The two ferrules 6 have their end faces facing each other, and the positioning keys 9 are inserted into the positioning grooves 15 and 1 of the alignment sleeve member, respectively.
6 and is tightened and fixed by cap nuts 19 and 20.

In this case, if the deviation α between the central axis of the slanted surface of the ferrule 6 and the positioning key is 0°, the gaps of the slanted surface of the ferrule 6 will be parallel.
is not 0°, the relative deviation of the central axis of the inclined surface is 2α
Therefore, the gap becomes an angle △θ as shown in the figure.
It becomes wedge-shaped.

FIG. 7 is an enlarged view of the tip of the ferrule in the case of the present invention and in the conventional case, where a shows the case of the present invention and b shows the conventional case, respectively.

In the figure, 6 indicates a ferrule, 8 indicates an optical fiber, and G indicates a gap.

From the figure, it can be seen that the gap G in the case of the present invention is smaller than that in the conventional case where the ferrule tip is entirely sloped because the ferrule tip is sloped leaving a flat surface. Therefore, the optical connection loss in the gap is reduced.

Furthermore, with this structure, it is also possible to evaluate the gap of the optical fiber due to polishing by measuring the distance from the fiber center to the ridge line where the slope and end face intersect and the amount of angular deviation between the two surfaces.

(7) Effects of the Invention As explained above in detail, the optical fiber connector of the present invention has a pair of ends whose end faces are divided into two by a line close to the optical fiber, and the side including the optical fiber is an inclined surface. By making it possible to position and hold the ferrule in the alignment sleeve member so that the ridge lines of its end faces are non-parallel, it is highly effective in preventing multiple reflections without causing connection loss. It is.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the structure of a conventional optical fiber connector, Figures 2 and 3 are diagrams for explaining multiple reflections at the end face of the optical fiber, and Figures 4 to 6 are diagrams for explaining the present invention. FIG. 4 is a cross-sectional view and a side view of a ferrule, FIG. 5 is a cross-sectional view and a side view of an alignment sleeve member, FIG. 6 is an assembled cross-sectional view, and FIG.
The figure is a diagram for explaining the gap in the present invention and the conventional optical fiber connector. In the drawings, 6 is a ferrule, 7 is an optical fiber cable, 8 is an optical fiber, 9 is a positioning key, 13 is an alignment sleeve member, 15 and 16 are positioning grooves, and 19 and 20 are cap nuts, respectively.

Claims (1)

[Scope of Claims] 1. A pair of ferrules 6 in which the optical fibers 8 are aligned and fixed, the distal end surfaces thereof are divided into two by a straight line close to the optical fibers, and the surface including the optical fibers 8 is an inclined surface; In an optical fiber connector comprising an alignment sleeve member 13 that supports the pair of ferrules with their tips abutted against each other, when the pair of ferrules 6, 6 are butted together, the ridge lines of their tip surfaces are non-uniform with each other. The ferrules 6, 6' and the alignment sleeve member 13 are aligned so that they are parallel to each other.
An optical fiber connector characterized in that positioning means is provided at the. 2 Ferrules 6, 6' as the positioning means
is provided with a positioning key 9, and the alignment sleeve member 1 is provided with a positioning key 9.
3. The optical fiber connector according to claim 1, wherein said ferrule is provided with a positioning groove 16 that engages with a positioning key 9 of said ferrule.