JPH1138269A - Optical connector and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embody stable PC coupling in spite of being multi core fiber, by providing a prescribed part of the butt end face of ferrule with a recessed part lower than the height of the fixing plane of optical fiber coupling part. SOLUTION: This optical connector consists of a structure having recessed parts in prescribed parts at the butt end faces of the ferrules. The prescribed parts refer to the parts between the fibers 15 and the fibers 15 and the parts between the boundary lines between the butt end faces of the ferrules and flanks 12 and the fibers 15. For example, these parts are provided with the recessed parts in such a manner that the surface sag of the connector end faces 12 arises toward the recesses. The recessed parts are so designed that the highest front end of the projecting fillers 14 in the ferrule resin parts after polishing are lower than the height at the front ends of the fibers 15 by taking the effect of such surface shear droop into consideration. While there are no particular limitations as to the positions, shapes, sizes and numbers or the recessed part, the recessed part like, for example, slender grooves, may be formed and the shapes of the grooves may be either square or curvilinear.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector for connecting an optical fiber (and a method for manufacturing the same).

[0002]

2. Description of the Related Art In an optical connector for connecting an optical fiber, (1) reduction (reduction of reflection) of reflected return light at a connection point and (2) return or scattering due to reflection at the connection point. Therefore, it is necessary to reduce light that does not propagate to the light receiving side (reduction of reflection loss).

For this reason, in a single-fiber connector, physical contact (PC) coupling (direct contact coupling between optical fiber end faces) has been studied.
A polishing machine for an optical connector as disclosed in Japanese Patent No. 7107 has been developed.

On the other hand, it is difficult for the multi-core connector to connect the whole core to the PC, and various attempts have been conventionally made. For example, in order to reduce the reflection, the end faces are obliquely polished and connected, or a refractive index matching agent having substantially the same refractive index as the core of the optical fiber is interposed between the end faces of the optical fibers to couple the optical connectors together. And Japanese Patent Application Laid-Open
As disclosed in Japanese Patent No. 34403, an attempt has been made to provide a resin film having a refractive index close to that of a core on an end face of an optical connector and connect the optical connectors to each other via the resin film. However, the connection method in which the end faces are polished obliquely does not eliminate the reflection loss, and in the connection in which the refractive index matching agent is interposed between the end faces, workability, handling, and dust easily enter between the optical fiber end faces. In the method of providing a resin film having a refractive index close to that of the core on the end face of the optical connector, the presence of the resin film lacks long-term reliability for the coupling operation of the optical connector, resulting in corrosion resistance and coupling strength. It is disadvantageous, and there is a problem in that increasing the thickness of the resin film to increase the strength of the resin film leads to an increase in loss of bonding.

Therefore, there is a long-awaited need for a technique that allows all the cores to be PC-coupled to a multi-core connector as well as a single-core connector. For example, an MPO connector is being developed.

However, in an MPO connector molded using a resin containing a filler, in a polishing step of projecting the optical fiber from the end face of the ferrule of the connector, the filler in the resin also protrudes from the end face without being polished. Inhibit physical contact with This state is shown in FIGS.
This will be described with reference to FIG. FIG. 1 is a schematic perspective view of a conventional connector body 1, FIG. 2 (a) is an enlarged sectional view of a connector end face portion 2 of FIG. 1 before polishing, and FIG. 2 (b) is an end portion after polishing. It is an expanded sectional view of. As is clear from FIG. 2B, in the conventional connector, the filler 4 protruding from the surface of the resin 3 due to the polishing of the butted end face 6 of the ferrule becomes higher than the tip of the optical fiber 5. . As described above, it is difficult for the multi-core connector to obtain stable PC contact by protruding only the optical fiber.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has a stable P-type even with a large number of cores.
An object of the present invention is to provide an optical connector capable of realizing C-coupling and a method of manufacturing the same.

[0008]

According to the first aspect of the present invention, optical coupling is realized by directly abutting optical fibers with each other.
An optical connector for connecting two or more optical fibers collectively, wherein the optical fibers are fixed to a ferrule by a resin including a filler, and a predetermined portion of a butt end face of the ferrule has a height of an optical fiber coupling portion fixing surface. It is characterized by having a structure having one or more recesses on the lower surface.

Here, the butted end face of the ferrule is
The optical fibers may be connected to each other by being brought into close contact with each other via at least one guide pin.

In addition, the butted end face of the ferrule can be formed into a spherical shape.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an optical connector for connecting a plurality of optical fibers at once, comprising the steps of: forming a ferrule with a resin containing a filler; , A step of inserting the optical fiber into a portion positioned for coupling the optical fibers, and a step of polishing the butted end face of the ferrule.

In the present invention, since the concave portion is provided at a predetermined position on the butt end surface, the filler in the concave portion protrudes based on the concave surface, and the tip of the highest protruding filler never becomes higher than the fiber. In addition, since the connector end surface is sagged toward the concave portion by polishing, the filler near the concave portion does not protrude higher than the fiber. Therefore, the optical fibers at the two coupling end faces can directly contact each other without being disturbed by the filler.

When spherical polishing is performed on the end face of the ferrule of the connector, the center of the end face becomes highest and becomes lower from the center toward the end. In the present invention, since the fiber is arranged near the center of the end face of the connector, the filler does not protrude from the resin portion outside the fiber higher than the tip of the fiber end. Therefore, when performing spherical polishing, the concave portion is provided on the end face between the fibers, and the central portion of the concave portion is formed so that the protrusion of the central filler is lower than the protrusion of the end fiber. By adjusting the depth, it is possible to realize a state where all the fibers protrude from the filler.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical connector according to the present invention has a structure having a concave portion at a predetermined portion of a butt end face of a ferrule. In the present invention, the predetermined portion is a portion between the fibers and a portion between the fiber and the boundary between the butted end face and the side face of the ferrule and the fiber (hereinafter, “outside of the fiber”).
Part). In the former case, the position of the concave portion is not particularly limited as long as the position of the concave portion is between the fibers, but is preferably near the center of the fiber. In the case of the latter portion, there is no particular limitation as long as the position of the concave portion is outside the fiber, but it is preferably near the center. Further, the shape, size, and number of the concave portions are not particularly limited. For example, an elongated groove-shaped concave portion can be provided, and the shape of the groove may be rectangular or curved. In this case, the shape (width and depth) of the concave portion is set to an appropriate size according to the arrangement pitch of the optical fibers and the particle size of the filler. For example, a fiber pitch of 0.25 mm
In the case of 0.05 to 0.10 mm width and 0.05 mm depth
As a guide, if the fiber pitch is 0.75 mm,
The width is about 0.4 to 0.5 mm and the depth is about 0.05 mm. In the present invention, the concave portion is provided so that the sag of the connector end surface is generated toward the concave portion. In consideration of the effect of the surface sagging, a design is made such that the highest tip of the projecting filler of the ferrule resin portion after polishing is lower than the height of the fiber tip.

In the optical connector of the present invention, the ferrule of the optical connector is formed of a resin containing a filler, and a concave portion is formed in a predetermined portion of the ferrule abutting end surface. The concave portion may be integrally formed when the ferrule is formed. .

In the present invention, the ferrule mating end face of the connector may be polished into a spherical shape. In this case, the tip of the optical fiber at the end portion of the ferrule mating end face is lower than the tip of the optical fiber at the central portion. ,
It is necessary to design so that the projecting tip of the filler near the center is not higher than the tip of the optical fiber at the end. For this purpose, for example, the concave amount of the central concave portion (the depth of the groove of the concave portion) is made larger than the concave amount of the end portion. The value of the concave amount of the concave portion depends on the size of the radius R of the spherical surface after polishing.
It needs to be changed accordingly. The end face of the connector can be polished by a usual polishing method.

In the present invention, the connector can be connected using a guide pin penetrating in the optical fiber axial direction. In this case, the connector has a guide pin hole penetrating in the optical fiber axial direction, and a guide pin is inserted into this guide pin hole to butt the mating end surfaces 16 (FIGS. 3 and 5) of the ferrule. They are optically coupled. However, the optical fiber end face is positioned and arranged on the ferrule butted end face. In addition,
The pair of optical connectors coupled in this manner may be stably held, for example, by being clipped by clips provided with a plate spring at both ends of the plate-shaped member.

[0018]

【Example】

Embodiment 1 FIGS. 3 and 4 show a first embodiment of the optical connector of the present invention. A ferrule of an optical connector was molded using an epoxy resin containing silica as a filler. However, a concave portion is provided on the coupling end surface of the ferrule almost at the middle of the position where the optical fiber is fixed. The amount of depression of the groove of the concave portion including the polishing margin was 0.05 mm, and the width of the concave portion was 0.4 mm. The optical fiber 15 is connected to the obtained ferrule by 0.75 m.
They were inserted side by side at m pitches and fixed with an adhesive. FIG. 4A is an enlarged view of the ferrule end of this connector. This surface was polished by a usual polishing method to obtain the connector of the present invention. FIG. 4 (b) shows a cross section after the polishing, from which it can be seen that the filler does not protrude from the end of the optical fiber end.

With respect to the obtained optical connector after polishing, a connector end face (ferrule mating end face) was measured using a surface shape measuring instrument. As a result, the distance from the tip of the protruded filler to the tip of the optical fiber was 0.5 to 0.5 mm. It was found to be about 1.0 μm. Further, the connection loss at N = 20 is 0.3 dB or less at the maximum, and the variation in attachment / detachment is 0.2 d.
B or less, which proved to be stable.

Embodiment 2 A second embodiment of the connector of the present invention will be described with reference to FIG. Two optical fibers are arranged at a pitch of 0.75 mm, and are fixed as a filler with an epoxy resin containing silica to form a ferrule. However, in this ferrule, concave portions are provided in the central portion of the two optical fibers and the outer portions of the fibers. The amount of the dent including the polishing margin was 0.05 mm, and the width of the dent was 0.4 mm.
The ferrule has a pitch of 0.75 between the two optical fibers.
mm, a two-core tape fiber was inserted and fixed with an adhesive. The ferrule end face was polished by a usual method to obtain a two-core optical connector of the present invention. The ferrule is provided with two guide pin holes 17 and optically coupled by inserting guide pins (not shown) into the guide pin holes and butting the ferrule mating end surfaces 16 of the connector. It has become.

With respect to the obtained optical connector after polishing, the connector end face was measured using a surface shape measuring instrument. As a result, the distance from the tip of the protruding filler to the tip of the optical fiber was about 0.5 to 1.0 μm. I found it. The connection loss at N = 20 was 0.3 dB or less at the maximum, and the attachment / detachment variation was 0.2 dB or less.

Third Embodiment Another third embodiment of the present invention will be described with reference to FIG. A pre-polished ferrule having a recess before polishing of 0.05 mm was produced in the same manner as in Example 2 except that one recess was provided at the center of the two optical fiber insertion portions on the butted end face 16 of the ferrule. . The ferrule end face was polished into a spherical shape using an oblique polishing plate to obtain an optical connector of the present invention. In addition,
This ferrule is provided with two guide pin holes 17 as in the second embodiment.

The protrusion height of the filler and the height of the tip of the optical fiber were measured using a surface shape measuring device on the ferrule butt end face of the obtained optical connector after polishing. As a result, it was confirmed that the height of the tip of the optical fiber at N = 20 was about 1 μm higher than the height of the tip of the protrusion of the filler. In this case, the connection loss was 0.3 dB or less at the maximum, and it was found that the variation in attachment and detachment was stable. The difference in connection loss between the case where the refractive index matching agent was added and the case where the refractive index matching agent was not added was 0.1 dB or less, and it was found that the opposing optical fibers were in contact.

[0024]

According to the present invention, by providing a concave portion in the portion between the fiber and the fiber on the connector end face and in the outer portion of the fiber, the protrusion of the fiber after polishing the connector end face can be made higher than the protrusion tip of the filler contained in the resin. did it. As a result, it is possible to stably realize direct contact between the fibers at the time of connecting the connector, thereby reducing the connection loss and the variation in attachment / detachment.

[Brief description of the drawings]

FIG. 1 is a perspective view of a conventional connector.

2 (a) is a partially enlarged sectional view of the connector end portion of FIG. 1 before polishing, and FIG. 2 (b) is a partially enlarged sectional view after polishing.

FIG. 3 is a perspective view of the connector according to the first embodiment of the present invention.

4 (a) is a partially enlarged sectional view of the connector end portion of FIG. 3 before polishing, and FIG. 4 (b) is a partially enlarged sectional view after polishing.

FIG. 5 is a perspective view of a connector according to a second embodiment of the present invention.

FIG. 6A is a perspective view of a connector according to a third embodiment of the present invention before polishing, and FIG. 6B is a perspective view after polishing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11 Connector body 1, 12 Connector end part 3, 13 Resin 4, 14 Filler 5, 15 Optical fiber 6, 16 Butt end face of ferrule 17 Guide pin hole

Claims (4)

[Claims] An optical connector for connecting two or more optical fibers at a time to realize optical coupling by directly abutting optical fibers with each other, wherein said optical fibers are fixed to a ferrule by a resin containing a filler. An optical connector, characterized in that the ferrule has a structure in which a predetermined portion of a butt end face of the ferrule has at least one concave portion having a surface lower than the height of the optical fiber coupling portion fixing surface. 2. The optical connector according to claim 1, wherein the butting end surfaces of the ferrule are positioned and brought into close contact with each other via at least one guide pin to connect the optical fibers. 3. The optical connector according to claim 1, wherein a butt end face of the ferrule has a spherical shape. 4. A method of manufacturing an optical connector for connecting a plurality of optical fibers collectively, comprising: forming a ferrule with a resin containing a filler; and forming a recess in a predetermined portion of a butt end face of the ferrule. A method of manufacturing an optical connector, comprising: a step of inserting an optical fiber into a portion positioned for coupling optical fibers; and a step of polishing a butt end face of a ferrule.