JPH0588046A - Optical connector - Google Patents

Abstract

(57) [Summary] [Configuration] The first ferrule 31A projects the end portion of the optical fiber 13A from the end surface by a predetermined length, and the second ferrule 31B causes the end surface of the optical fiber 13B to retract from the end surface. The optical fiber fitting hole 23B. Cavities 33A and 33B are provided at the tips of the optical fiber fitting holes 23A and 23B of the ferrules 31A and 31B. [Effect] Since the end faces of the optical fibers 13A and 13B are butted against each other in the optical fiber fitting hole 23, the axial misalignment of the optical fibers can be reduced. Two ferrule fiber optic holes 23
Even if the A and 23B are misaligned, the optical fiber 13A has a cavity 33.
Bending in A and 33B can absorb the misalignment. For this reason, the accuracy of the ferrule can be made lower than before, and the manufacturing becomes easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector used for connecting optical fiber core wires.

[0002]

2. Description of the Related Art A conventional optical connector is shown in FIGS. Reference numerals 11A and 11B are optical fiber core wires to be connected, 13
A and 13B are optical fibers at the tip thereof, and 15A and 15B are coating portions. 21A and 21B are optical fiber cores 11A and 11B.
It is a ferrule attached to the end of.

The ferrules 21A and 21B have a required number of optical fiber fitting holes 23A and 23B formed perpendicularly to the end face on the front end side, and a covering portion inserted into the optical fiber fitting holes 23A and 23B on the rear end side. Holes 25A and 25B are formed. The optical fibers 13A and 13B of the optical fiber core wires 11A and 11B are inserted into the optical fiber fitting holes 23A and 23B, and the covering portion insertion holes 25A and 25 are formed.
The coating portions 15A, 15B of the optical fiber core wires 11A, 11B are inserted in B and fixed by means such as adhesion.

Further, pin fitting holes 27A and 27B are formed on both sides of the optical fiber fitting holes 23A and 23B in the same direction. Two ferrules 21A and 21B have both pin fitting holes
The guide pins 29 are positioned so as to straddle 27A and 27B, and the ends are abutted. As a result, the optical fibers 13A and 13B are optically connected.

[0005]

In the optical connector having such a structure, the optical fiber fitting holes 23A and 23B have the pin fitting holes.
If there is no high-precision and fixed positional relationship with 27A and 27B,
There is a problem that the optical fibers 13A and 13B are misaligned and the connection loss increases.

FIG. 8 shows the relationship between the axial displacement and the connection loss. S
M is a single mode optical fiber, and GI is a graded index optical fiber. For example SM
Since the optical fiber has a very small core diameter of about 5 to 10 μm, it is necessary to make the axial deviation extremely small in order to reduce the splice loss. Generally, it is required to reduce the connection loss to about 0.2 to 0.4 dB on the trunk line of the telephone line, so if you try to reduce the connection loss to 0.3 dB or less, for example,
The axial misalignment must be 1.2 μm or less.

However, it is not easy to manufacture such a high-precision ferrule by the current die technology and molding technology, which causes the manufacturing cost of the ferrule to increase. In view of the problems as described above, an object of the present invention is to provide an optical connector that can reduce the axial misalignment of an optical fiber to be connected without making the positional relationship between the optical fiber fitting hole and the pin fitting hole highly accurate. To provide.

[0008]

The optical connector of the present invention comprises:
It is provided with two ferrules for connecting the optical fibers by abutting the end faces of each other, the first ferrule has an end portion of the optical fiber protruding from the end face by a predetermined length, and the second ferrule has the first end face from the end face. The end face of the optical fiber is retracted by the amount corresponding to the protruding length of the optical fiber on the ferrule side, and the end face of the optical fiber is positioned in the optical fiber fitting hole. Is characterized in that a cavity for allowing the bending of the optical fiber on the side of the first ferrule is provided at the tip of the.

[0009]

In this optical connector, when the end faces of the two ferrules are butted, the end of the optical fiber protruding from the end face of the first ferrule is inserted into the optical fiber fitting hole of the second ferrule, Then, the optical fiber on the side of the second ferrule is brought into abutment with the end face. That is, since the optical fiber to be connected is positioned only by the optical fiber fitting hole of the second ferrule, it is possible to align the axes accurately and easily.

When the end faces of the two ferrules are butted against each other, even if there is some axial misalignment in the optical fiber fitting hole,
The end of the optical fiber on the side of the first ferrule bends in the cavity provided at the end of the optical fiber fitting hole, so that the axial deviation can be absorbed. Therefore, it is not necessary to maintain the positional relationship between the ferrule positioning portion such as the pin fitting hole and the optical fiber fitting hole with high accuracy, and the ferrule is easily manufactured.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 to 3 show an embodiment of the present invention. This optical connector has a first ferrule 31A and a second ferrule 31B. Two ferrules 31
A and 31B are optical fiber fitting holes 23A into which the optical fibers 13A and 13B of the optical fiber core wires 11A and 11B are fitted, respectively.
23B and a covering portion insertion hole 25 into which the covering portions 15A and 15B are inserted
A, 25B, and the optical fiber fitting hole 23A,
23B has cavities 33A and 33B whose inner diameters gradually increase from the optical fiber fitting holes 23A and 23B.

In the first ferrule 31A, the end portion of the optical fiber 13A is projected from the end surface by a predetermined length. In this state, the first ferrule 31A and the optical fiber core wire 11A have the first ferrule 31A. The concave portion formed from the covering portion insertion hole 25A to the optical fiber fitting hole 23A is fixed by filling an adhesive 35.

In the second ferrule 31B, the end face of the optical fiber 13B is retracted from the end face by a predetermined length so that the end face of the optical fiber 13B is located in the optical fiber fitting hole 23B. The ferrule 31B and the optical fiber core wire 11B of the second ferrule 31B correspond to the covering portion insertion hole 25 of the second ferrule 31B.
The concave portion formed from B to the optical fiber fitting hole 23B is fixed by filling an adhesive 35.

As in the conventional case, the two ferrules 31A and 31B are provided with pin fitting holes 27A and 27B on both sides of the optical fiber fitting holes 23A and 23B as shown in FIG. By inserting the guide pin 29 across 27A and 27B, the two ferrules 31A and 31B are positioned.

Next, a connection method using this optical connector will be described. First, use the guide pin 29 to connect the two ferrules 31A and 31B.
When the end faces of the two ferrules 31A and 31B are brought close to each other by inserting the pin so as to straddle the pin fitting holes 27A and 27B, the optical fiber on the first optical ferrule 31A side as shown in FIG.
The tip of 13A enters the cavity 33B of the second ferrule 31B, and then the tip of the optical fiber 13A is guided by the inner surface of the cavity 33B and enters the optical fiber fitting hole 23B.

When the end faces of the two ferrules 31A and 31B are abutted, the optical fibers 13A and 13B are abutted in the optical fiber fitting hole 23B with a minute gap therebetween as shown in FIG. As a result, the misalignment of the optical fibers 13A and 13B is
It is determined only by the inner diameter of the optical fiber fitting hole 23B.

The inner diameter of the optical fiber fitting hole 23 is set to the optical fiber 13
Since it is possible to easily form the outer diameters of A and 13B by about 1 μm with the current molding technology, the misalignment between the optical fibers 13A and 13B in the optical fiber fitting hole 23 is about 0.5 μm. Can be According to FIG. 8, since the connection loss at this time is about 0.1 dB, the connection loss can be suppressed sufficiently low. Optical fiber
The minute gap between the end faces of 13A and 13B is filled with the matching oil that has been injected into the optical fiber fitting hole 23B in advance.

When the end faces of the two ferrules 31A and 31B are butted, the optical fiber fitting holes 23A and 23B of both ferrules 31A and 31B are brought into contact with each other.
When the B axial misalignment occurs, the optical fiber 13A bends in the cavities 33A and 33B, so that the axial misalignment can be absorbed. Therefore, it is not necessary to control the positions of the optical fiber fitting holes 23A and 23B with respect to the pin fitting holes 27A and 27B on the order of submicrons, and the ferrules 31A and 31B are provided.
Manufacturing becomes easier.

In the above embodiment, the cavity at the tip of the optical fiber fitting hole is provided in both ferrules, but this cavity may be provided in only one of the ferrules.
Further, the end faces of the optical fibers 13A and 13B need to be polished in advance, but at the time of connection, the cavity 33 on the second ferrule 31B side is formed.
In order to prevent the inner surface of B from being scratched, the end surface is processed into a spherical surface or R, so-called PC (Physical Contac
t) Connection is preferable.

FIG. 4 shows another embodiment of the present invention. In this optical connector, a wall 37 is provided at the tip of the first ferrule 31A so as to surround the end of the optical fiber 13A protruding from the end face thereof.
And the tip of the second ferrule 31B,
It is formed so as to enter the inside of the wall 37. In this way, the optical fiber 13A protruding from the end face of the first ferrule 31A can be protected. Since the configuration other than the above is the same as that of the above-described embodiment, the same reference numerals are given to the same portions and the description thereof will be omitted.

FIG. 5 shows still another embodiment of the present invention.
In this optical connector, the projecting length of the optical fiber 13A from the end face of the first ferrule 31A is made slightly longer than that of the above-mentioned embodiment, and the optical fiber 13A is bent in the cavities 33A and 33B by the elastic force. The end surfaces of 13A and 13B are always in contact with each other. By doing so, more stable connection characteristics can be obtained. Since the configuration other than the above is the same as that of the above-described embodiment, the same reference numerals are given to the same portions and the description thereof will be omitted.

[0022]

As described above, according to the present invention, since the end faces of the optical fibers to be connected are butted against each other in the optical fiber fitting holes of the second ferrule, the axial misalignment of the optical fibers can be suppressed to be extremely small. It is possible to make a connection with less connection loss. Also, even if there is some axial misalignment in the optical fiber fitting holes of the two ferrules, the optical misalignment can be absorbed by bending the optical fiber on the first ferrule side in the cavity. The accuracy of the position of the fitting hole can be made lower than before. Therefore, there is an advantage that the ferrule can be easily manufactured and the manufacturing cost of the ferrule can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a state before connection of an optical connector according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a state after connection of the optical connector of FIG.

FIG. 3 is a perspective view of the optical connector of FIG. 1 in a separated state.

FIG. 4 is a vertical sectional view showing an optical connector according to another embodiment of the present invention.

FIG. 5 is a vertical sectional view showing an optical connector according to still another embodiment of the present invention.

FIG. 6 is a sectional view of a conventional optical connector.

7 is an end view of one ferrule of the optical connector of FIG.

FIG. 8 is a graph showing the relationship between axial misalignment and connection loss when connecting optical fibers.

[Explanation of Codes] 11A, 11B: Optical fiber core wires 13A, 13B: Optical fibers 15A, 15B: Covering portions 23A, 23B: Optical fiber fitting holes 25A, 25B: Covering portion insertion holes 27A, 27B: Pin fitting holes
29: Guide pin 31A: First ferrule 31B: Second ferrule
33A, 33B: Cavity 35: Adhesive 37: Wall

Claims (2)

[Claims] 1. A first ferrule comprising two ferrules having end faces abutting each other and connecting optical fibers to each other.
The end portion of the optical fiber is projected from the end surface by a predetermined length, and the second ferrule causes the end surface of the optical fiber to be retracted by an amount corresponding to the optical fiber protruding length on the first ferrule side from the end surface. The end face of the fiber is located in the optical fiber fitting hole, and a cavity that allows bending of the optical fiber on the first ferrule side is provided at the tip of the optical fiber fitting hole of at least one of the two ferrules. An optical connector characterized in that 2. The optical connector according to claim 1, wherein the first ferrule is provided with a wall so as to surround the end portion of the optical fiber protruding from the end face thereof.