JP4248063B2 - Multi-fiber optical connector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical connector of a pin fitting alignment method called a so-called MT type optical connector, and more particularly to an optical connector using a graded index type optical fiber and having a connector contact end face of a physical contact.
[0002]
[Prior art]
FIG. 1 is a view common to the conventional example and the present invention. As shown in FIG. 1, a generally square ferrule 1 having a hole (guide pin hole) 1a for fitting an alignment pin (guide pin) is provided. An optical connector 3 in which the optical fiber 2 is inserted and fixed is used in a JIS C 5981 F12 type multi-core optical fiber connector and is generally known as an MT optical connector. 4 is an optical fiber ribbon, and 5 is a resin boot for protection.
[0003]
An optical connector that can be connected by push-on / pull-off one-touch operation by mounting this type of MT optical connector on the housing is a so-called MPO optical connector (JIS C 5982 F13 type multi-core optical fiber connector). However, this type of MPO optical connector generally performs so-called physical contact connection that directly contacts the end face of the optical fiber without using a refractive index matching agent on the end face of the connector.
[0004]
In order to form this physical contact joining end face, the ferrule end face is polished. Conventionally, as shown in FIG. 4, polishing is performed to protrude the optical fiber end face 2a from the ferrule end face 1b by about several μm (in FIG. 4). H dimension is several μm). 2b represents the core of the optical fiber 2, and 2c represents the cladding of the optical fiber 2. The optical fiber end face 2a is protruded by several μm from the ferrule surface 1b in this way by special polishing that pays attention to the difference between the hardness of the optical fiber 2 that is glass and the hardness of the ferrule 1 using epoxy resin or the like. It is.
[0005]
[Problems to be solved by the invention]
By the way, when this type of optical connector (MT optical connector) 3 is protruded and polished, an optical connector with an SM optical fiber (single mode optical fiber) can obtain good optical characteristics, whereas multimode light can be obtained. In the case of an optical connector to which a GI optical fiber (graded index type optical fiber) that is a fiber is attached, the optical characteristics are poor. This is because when the core diameter is as small as 10 μm as in the SM optical fiber, the core portions are sufficiently brought into contact with each other when the optical fibers are brought into contact with each other. Since the diameter is as large as 50 μm, the cores are brought into contact with each other only in a part of each other.
[0006]
The present invention has been made to solve the above-described conventional drawbacks, and an object of the present invention is to provide an optical connector capable of obtaining good optical characteristics in an MT optical connector to which a graded index optical fiber is attached. To do.
[0007]
[Means for Solving the Problems]
The present invention for solving the above-described problems is to insert and fix a plurality of graded index type optical fibers into a generally rectangular ferrule having a hole for fitting an alignment pin, and connect the connector joining end face to the end face of the optical fiber. Is a multi- fiber optical connector formed in a form protruding from the ferrule end face,
The protruding portion protruding from the ferrule end surface of the optical fiber has a circular flat surface having a diameter 25% or more larger than the core diameter of the optical fiber by polishing, and the gap between the front end surface and the ferrule end surface is narrow. It is characterized by being formed to have a conical curved surface .
Here, the frustoconical curved surface is a curved surface that is close to the outer peripheral surface of the truncated conical body, which is a solid obtained by horizontally cutting off the top side of the cone, but whose outer peripheral surface bulges outwardly. It means that there is.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. The optical connector of the embodiment is the optical connector 3 of FIG. 1 described above, and the optical fiber 2 is inserted through a generally rectangular ferrule 1 having a hole (guide pin hole) 1a for fitting an alignment pin (guide pin). This is a fixed configuration, which is used in a JIS C 5981 F12 type multi-core optical fiber connector, and is generally known as an MT optical connector. Reference numeral 4 denotes an optical fiber ribbon. The optical fiber 2 is the optical fiber (bare fiber) tip portion itself of the optical fiber ribbon 4 or a short optical fiber separately accommodated and fixed connected to the optical fiber of the optical fiber ribbon 4. Either. Reference numeral 5 denotes a resin boot for protection.
[0010]
In the present invention, as shown in FIG. 3, the protrusion protruding from the ferrule end face of the optical fiber 2 has a diameter D larger than the diameter d of the core 2b of the optical fiber 2 on the end face that becomes the joining end face 2a by polishing. It has a circular flat surface 2d, and is formed so that a frustoconical curved surface is formed between the tip surface and the ferrule end surface. Here, the frustoconical curved surface is a curved surface that is close to the outer peripheral surface of the truncated conical body, which is a solid obtained by horizontally cutting off the top side of the cone, but whose outer peripheral surface bulges outwardly. It means that there is. The core diameter of the GI optical fiber is 50 μm, and a flat surface having a diameter of 25% or more of the core diameter, that is, a diameter of 62.5 μm or more is formed . 2c is a clad, 1 is a ferrule, and 1b is a ferrule end face .
[0011]
According to the optical connector 3 in which the flat surface 2d is formed on the joining end surface of the optical fiber 2 as described above, since the width of the flat surface 2d is larger than the diameter d of the core 2b of the optical fiber 2, the optical connectors 3 are connected to each other. When they are brought into contact with each other, they come into contact with each other. Therefore, even if the core 3b diameter of the optical fiber 3 of the graded index type is as large as 50 μm, the entire surface of the core 2b can be reliably brought into contact. Thereby, the physical contact connection of the optical connector 3 becomes easy.
[0012]
The optical connector 3 of the present invention is suitable for use as an optical connector portion of an MPO optical connector 10 as shown in FIG. The MPO optical connector 10 includes an optical connector portion 3A having the same structure as the optical connector 3 described above, a housing 11 that accommodates the optical connector portion 3A so as to be movable forward and backward (left and right in FIG. 2), and an optical connector portion 3A. A spring 12 for pressing, a coupling 13 having a generally rectangular tube shape provided on the outer periphery of the housing 11, a spring 14 for pressing the coupling 13, a rear housing 15 attached to the rear portion of the housing 11 with an engaging claw 15a, a ferrule 1 The pin clamp 17 etc. which clamp the alignment pin 16 passed through the hole 1a. With this configuration, it is possible to connect a connector for push-on / pull-off one-touch operation.
[0013]
Na you, it can also be applied to large diameter optical fiber other than the above embodiments.
[0014]
【The invention's effect】
According to the multi- fiber optical connector of the present invention, the protruding portion protruding from the ferrule end face of the optical fiber accommodated and fixed in the ferrule is polished to a circular shape having a diameter 25% or more larger than the core diameter of the optical fiber by the polishing process . Since it has a flat surface and is formed so that the front end surface and the ferrule end surface are curved frustoconical curved surfaces , when the optical connectors are brought into contact with each other, they come into contact with each other, and therefore the graded index Even if the core diameter of this optical fiber, which is a mold, is as large as 50 μm, the entire surface of the core can be brought into contact with certainty, for example, if it is 62.5 μm or more. Thereby, the physical contact connection of the optical connector 3 becomes easy.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of an optical connector to which the present invention is applied.
2 shows an application example of the optical connector of the present invention, and is a plan view showing a main part of a so-called MPO optical connector using the optical connector (so-called MT optical connector) of FIG. 1 in a horizontal section.
3 is an enlarged cross-sectional view (corresponding to a cross-sectional view taken along the line AA in FIG. 1) of an end face portion of the optical fiber in the optical connector of the present invention.
4 is an enlarged cross-sectional view (corresponding to a cross-sectional view taken along the line AA in FIG. 1) of an end face portion of an optical fiber in a conventional optical connector.
[Explanation of symbols]
1 Ferrule 1a hole (guide pin hole)
1b Ferrule end face 2 Optical fiber (bare fiber)
2a Optical fiber joint end face 2b Core 2c Clad 3 Optical connector 3A MPO optical connector optical connector 4 Optical fiber tape core 10 MPO optical connector 11 Housing 12 Spring 13 Coupling 16 Guide pin

Claims (1)

A plurality of graded index type optical fibers are inserted into and fixed to a generally square ferrule having a hole for fitting an alignment pin, and a connector joining end surface is formed such that the end surface of the optical fiber protrudes from the end surface of the ferrule. A multi- fiber optical connector,
The protruding portion protruding from the ferrule end surface of the optical fiber has a circular flat surface having a diameter 25% or more larger than the core diameter of the optical fiber by polishing, and the gap between the front end surface and the ferrule end surface is narrow. A multi- fiber optical connector formed so as to have a conical curved surface .

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