JPH05181040A - Optical connector and its production - Google Patents

Abstract

PURPOSE:To obtain the optical connector which is high in the amount of attenuation by reflection and can be easily produced. CONSTITUTION:Two pieces of optical fibers 1 and 2, the cores of which are formed to a hemispherical shape, are connected by butting the respective hemispherical cores 11, 12 against each other. The optical fibers 1 and 2 are single- mode fibers having 10mum core diameter and 125mum outside diameter. The length of the projection of the cores formed to the hemispherical shape is about 3mum. The optical fibers 1 and 2 are inserted and fixed in ferrules 3 and 4 made of ceramics. The hemispherical cores are butted and connect against and to each other in the state of optical contact by tightening screws 6 and 7 via a sleeve 5 made of a stainless steel. An etching method is used as a method of forming the cores to the hemispherical shape and, therefore, the complication associated with the conventional polishing stage is eliminated and the core end faces are easily made into the hemispherical shape.

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 optical communication for connecting an optical signal propagating through an optical fiber to another optical fiber.

[0002]

2. Description of the Related Art An optical connector for easily connecting optical fibers, which is an optical transmission line of an optical communication system, is one of important devices for constructing an optical communication system.

Conventionally, as an optical connector with good performance, for example, Electronic Information Communication Handbook, 1988, No. 1
The optical connector described in the separate volume, pages 1034 to 1035, can be given. In this optical connector, two hemispherical end faces of two single mode fibers whose end faces are processed into a hemispherical shape are butted and connected.

By making the end faces hemispherical in this way, the cores also become hemispherical, which allows a sufficient butting of the cores (this butting state is usually called "optical contact"). As compared with the case where the end face is flat, the reflectance at the abutting face becomes smaller, and the return loss that contributes to the stability of the transmission characteristics and the like can be increased.

[0005]

A polishing process is generally used to form the end face of a single mode fiber into a hemispherical shape. In this polishing step, since a minute end face of the optical fiber is polished, more man-hours are required than in the ordinary flat polishing step.

Therefore, there is a drawback that the cost of the optical connector becomes high. Furthermore, in the case of an array-shaped optical connector in which a plurality of optical fibers are arranged, it is difficult to make each optical fiber end face into a hemispherical shape because polishing is usually performed after the optical fibers are arrayed, and thus it is difficult to make each optical fiber into a hemispherical shape. It was difficult to obtain a sufficiently low reflectance on the butted surfaces.

An object of the present invention is to provide an optical connector which has a large return loss and can be manufactured without a complicated polishing process, and a manufacturing method thereof.

[0008]

In order to achieve the above object, an optical connector according to the present invention is an optical connector for connecting optical fibers in series by abutting each core end face to face each other. The core end surface of the fiber is formed into a hemispherical shape with a required protrusion amount by etching.

Further, two or more optical fibers are arranged in parallel, each optical fiber has a hemispherical core end face, and the clad end faces of the corresponding fibers are butted and connected.

A method of manufacturing an optical connector according to the present invention is a method of manufacturing an optical connector in which core end faces of optical fibers are butted and connected to each other, and the higher the core dopant concentration of the optical fiber, the slower the etching rate is. The core of the end face of the optical fiber is formed into a hemispherical shape by etching the end face of the fiber.

Further, in a method of manufacturing an optical connector in which core end faces of optical fibers are butted and connected to each other, the optical fiber end faces obtained by arranging and integrating a plurality of optical fibers in parallel are slower as the core dopant concentration is higher. By etching with an etching solution, the end faces of the cores of the optical fiber are collectively formed into a hemispherical shape.

[0012]

In general, the refractive index distribution of the core of a single-mode fiber is ideally a step type, so the core dopant concentration is designed to be substantially constant within the core. However, in reality, the dopant in the core is diffused due to thermal diffusion during fiber production, and the dopant concentration distribution becomes a distribution that decreases in a square distribution with respect to the distance from the central axis.

Therefore, the core portion can be formed into a hemispherical mold by etching the fiber end face with an etchant having a slower etching rate as the dopant concentration is higher. Since the present invention hemispheres the core by etching,
The process is not complicated unlike the conventional polishing process, and the cost of the optical connector can be easily reduced.

In the case of manufacturing a plurality of optical fibers arranged in an array, the end faces of the optical fibers are arranged in an array, the end faces of the optical fibers are collectively polished flat, and then the above-mentioned etching solution is used. Thus, a plurality of cores can be collectively formed into a hemispherical shape by etching the end face of the optical fiber. In this way, the individual cores can be collectively formed into a hemispherical shape. Therefore, a sufficient low reflectance can be obtained at the abutting surface of each optical fiber, and the cost of the array optical connector can be easily reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of the present invention. In the figure, two optical fibers 1 and 2 each having a hemispherical core end surface are shown as hemispherical core end surfaces 11 and 2, respectively.
Twelve of them are butted and connected. Here, the optical fibers 1 and 2 have a core diameter of 10 μm and an outer diameter of 125 μm.
Of single-mode fiber, and the protrusion amount of the hemispherical core is about 2 μm. The optical fibers 1 and 2 are inserted and fixed in the ceramic ferrules 3 and 4, and the hemispherical core end surfaces 11 and 12 are butted to each other with the stainless steel sleeve 5 and the tightening screws 6 and 7 in the optical contact state. It is connected.

The etching solution for hemispherically etching the core of the end face of the single mode fiber is 49% hydrofluoric acid (HF) and 40% ammonium fluoride (NH).
₄ F) in a weight ratio of 1:10.

The etching time for obtaining the core protrusion amount of 2 μm in this embodiment is about 2 hours and 15 minutes at room temperature (see FIG. 2). In the present invention, since etching is used as a method for forming the core into a hemispherical shape, it is possible to easily make the core into a hemispherical shape without being complicated as in the conventional polishing process.

Since the etching time can be shortened by raising the temperature of the etching solution, it is easy to shorten the above-mentioned etching time and further improve the work efficiency. Also, the etching solution does not have to be limited to the above,
The higher the dopant concentration, the slower the etching rate may be.

An optical connector having a low reflectance was obtained with the above-described structure, and the return loss was 40 dB or more, which is the same level as the conventional one, and was very good.

FIG. 3 is a sectional view of a four-channel array optical connector showing a second embodiment of the present invention. In the figure, eight optical fibers 1a each having a hemispherical core
1d and 2a to 2d are fixed and integrated in V grooves formed on the surfaces of the silicon (Si) substrates 8 and 9 at a pitch of 250 μm.

The silicon (Si) substrates 8 and 9 are
Inserted and fixed in the ceramic ferrules 3 and 4,
The hemispherical cores are butted and connected to each other in an optical contact state by tightening screws 6 and 7 via a sleeve 5 made of stainless steel.

The optical fibers 1a to 1d and 2a to 2d.
The shape and dimensions of are the same as in the case of the first embodiment. The method for producing the above-described arrayed optical fibers 1a to 1d and 2a to 2d is as follows. First, four single mode fibers are arranged and fixed in the V grooves on the surfaces of the silicon substrates 8 and 9, Next, the end faces of the single mode fiber are collectively polished flat.

After that, the flat end face is etched with the etching solution used in the first embodiment to collectively form a hemispherical core. As described above, since a plurality of cores can be collectively formed into a hemispherical shape, the end faces of individual optical fibers can be easily formed into a hemispherical shape. In this embodiment, a very good array optical connector with return loss of 40 dB or more for all four channels was obtained.

In the above two embodiments, the single mode fiber was used as the optical fiber, but the present invention is not limited to this, and a similar effect can be obtained with a focused multimode fiber having a focused dopant distribution. Further, although the number of channels is set to 4 in the second embodiment, the number of channels is not limited to this and 4
It may be used for more than channels.

[0025]

As described above, according to the present invention, it is possible to obtain an optical connector which has a large return loss, does not require a complicated polishing step in the past, and can be easily reduced in cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a relationship diagram showing a relationship between an etching time and a core protrusion amount.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 1,2,1a to 1d, 2a to 2d Optical fiber 3,4 Ferrule 5 Sleeve 6,7 Tightening screw 8,9 Silicon substrate

Claims (4)

[Claims] 1. An optical connector for connecting optical fibers in series by abutting each core end face to face each other, wherein the core end face of each optical fiber is formed into a hemispherical shape with a required protrusion amount by etching. Optical connector characterized by being a thing. 2. Two or more optical fibers are arranged in parallel, each optical fiber has a hemispherical core end surface, and clad end surfaces of corresponding fibers are butt-connected. The optical connector according to claim 1, wherein: 3. A method of manufacturing an optical connector in which core end faces of an optical fiber are butted and connected to each other, wherein the optical fiber end face is etched with an etching solution having a slower etching rate as the core dopant concentration of the optical fiber is higher. A method of manufacturing an optical connector, characterized in that the core of the fiber end face is formed in a hemispherical shape. 4. A method of manufacturing an optical connector, in which core end faces of optical fibers are butted and connected to each other, wherein an end face of an optical fiber in which a plurality of optical fibers are arranged in parallel and integrated
A method for manufacturing an array optical connector, characterized in that an end face of each core of an optical fiber is collectively formed into a hemispherical shape by etching with an etching solution having a slower etching rate as the core dopant concentration is higher.