JPS5933882B2 - Multi-core optical fiber connector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for connecting a plurality of optical fibers, and particularly relates to connecting a multi-core bidirectional transmission line using an optical splitter.

Conventionally, there have already been many reports regarding multi-core optical fiber connectors, and studies are also underway on reliability and economy for practical use.

However, all of these fiber connectors are for unidirectional optical transmission, and the optical fiber end face is also manufactured at right angles.
Multi-core optical fiber connectors using inclined end faces used for bidirectional optical transmission have not yet been considered. however,
This is one of the things that will be required as high-performance optical splitters are developed in the future. The present invention eliminates the drawbacks of the prior art described above, and details of the present invention will be explained below with reference to drawings showing embodiments.

1 and 2 are diagrams of the basic principle of the present invention. Now consider the optical fibers 1, V and 2, 2' to be connected. When light beams that are reflected and propagated at the maximum angle of total reflection on the cladding surface are incident on 1 and 2, the rays 3 and 4 proceed as shown by the arrows while being totally reflected on the cladding surface, and the reflected waves are reflected on the inclined surfaces 5 and 6, respectively. 3' and 4', and the refracted waves proceed to 2 and 4''. Here, the reflected waves 3' and 4', which are a problem for bidirectional transmission lines, are larger than the maximum total reflection angle φ on each cladding surface. Therefore, the light is attenuated while leaking out of the core.This condition is /n to -n2/n1<, where n, , and n2 are the refractive indices of the core and cladding, respectively.
It is sufficient to satisfy θ<π/2−(/nl−nth/nl). The optical fibers under the above conditions are arranged on the outer peripheries of concave and convex round bars 7 and 8 with conical ends so that the inclination direction of each optical fiber is continuous with the conical inclination, and each fiber is are arranged around the outer periphery of the round bars 7 and 8 without any gaps.

Next, one embodiment of the present invention will be described with reference to FIGS. 3 to 5.

In the figure, 9 and 10 are optical fiber cables to be connected. Numerals 11 to 14 abut on a convex round bar member 15 and a concave round bar member 16, each having a conical tip, in the state of a cladding portion with the nylon coat removed.

At this time, the tip inclined portions of the optical fiber clads 11 to 14 are set so that the conical inclinations of both the convex and concave round bar members are continuous. In this state, rotation stopping member 17 is inserted to suppress rotation in the circumferential direction. Next, round bar member 1
The outer sides of the optical fibers arranged on the outer circumferences of the optical fibers 5 and 16 are fixed by holding members 17 and 18, respectively.

In this case, the inner diameter of the holding members 17 and 18 is set to be approximately the outer diameter when the optical fibers are arranged on the round bar members 15 and 16. Both fiber cables 9 and 10 are completely held by the holding member 17.
, 18 using cap nuts 19 and 20,
The tightening connection to the sleeve 21 is completed. In addition, in the above explanation, the round bar member was referred to as a round bar member, but it may be hollow.
In short, any cylindrical member may be used.

FIG. 5 is a diagram in which the connector of the present invention is introduced into an optical transmission line using an optical splitter, and 22 and 23 are connectors.

24 and 25 are optical splitter groups.

26 and 27 are LEDs. Light emitting element group such as LD, 29, 28
is a group of light receiving elements such as PIN diodes and APDs.

Assuming that the light emitting elements 26 and 27 convert signals into light and transmit them, the branch groups 24 and 25 and the connector 2
2 and 23, the respective signals are received by light receiving elements 28 and 29.

Therefore, as in the case of using right-angled end faces, the signal emitted from the light emitting element 27 is reflected by the end faces of the connectors 22 and 23, returns to the light receiving element 29 via the splitter 24, and the light is emitted from the light emitting element 26. There is no possibility that crosstalk will occur due to overlapping with other signals. As described above, in the multi-core optical fiber connector of the present invention, since the central cylindrical member and the inclined fiber have the same inclination and form a conical shape with continuous unevenness, axis misalignment is difficult to occur, and the central cylindrical member Since the inclined fibers are arranged without gaps around the outer circumference of the fiber, the characteristics of each individual fiber connection are uniform and axis alignment is easy.Furthermore, by changing the diameter of the central cylindrical member, the number of fibers can be changed freely. In addition, since the rotation stopper is provided in contact with the fibers, displacement caused by rotation is less likely to occur.

Furthermore, since the end face of the optical fiber has a predetermined slope, there is no reflection and almost no light loss occurs.

[Brief explanation of drawings]

Fig. 1 is a diagram of the basic principle of the present invention, Fig. 2 is a side view of Fig. 1, Fig. 3 is a side sectional view of a multi-core connector according to an embodiment of the invention, and Fig. 4 is a side view of Fig. 3. 5 are conceptual diagrams in which the present invention is applied to an optical branching transmission line. 1,1″,2,2″・・・Optical fiber, 3,4・
...゛゜Incoming wave, 3', 4'...Reflected wave, 3
', l...Refracted wave, 5, 6... Inclined surface, 7, 8... Round bar, 9, 10... Optical fiber cable, 11 〜１４・・・・・・・・・Clatsud, 1
5... Convex round bar member, 16... Concave round bar member, 17, 18... Holding member, 19, 20
...Fukuro Natsutto, 21...Sleeve.

Claims (1)

[Claims] 1 The angle θ of the end face of the optical fiber with respect to the optical axis is √(n_1
^2-n_2^2)/n_1<θ<π/2-(√[n_
1^2-n_2^2]/n_1) However, when connecting a plurality of optical fibers with an end face angle θ that satisfies the relationship n_1: refractive index of the core n_2: refractive index of the cladding, a pair of optical fibers to be connected Each of the optical fibers with inclined end faces of the bundle is brought into contact with the outer periphery of a conical cylindrical member attached to the center and has an uneven surface having an inclination equal to the end face angle of the inclined optical fiber, and the adjacent optical fibers are brought into contact with the outer periphery of the cylindrical member. A multi-core optical fiber connector for connecting the pair of optical fiber bundles arranged without gaps. 2. A multicore optical fiber according to claim 1, in which a cylindrical member is used as a positioning pin, and the cylindrical member is in contact with both outer peripheries of adjacent optical fibers at at least one point among the optical fibers arranged without gaps around the outer periphery of the cylindrical member. connector.