JP2003315596A - Optical fiber connection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for splicing optical fibers by which work hours can be reduced and the parts of spliced optical fibers can be made small by optimizing the protection and reinforcement of the fusion-spliced parts with a necessary minimum configuration in using the optical fibers that do not cause a large physical stress. <P>SOLUTION: The coating of a tip of a pair of optical fibers 11 is removed, the tips of the optical fibers 11 are spliced by fusion, and the fusion-spliced part 14 and a coating-removed part 12 are covered and protected with/by a rigid sleeve 15. A thin sleeve with the outer diameter being ≤1 mm is used for the sleeve 15 to protect the parts 14 and 12. The sleeve 15 is adhesively fixed by an adhesive resin having flexibility after curing, or only one end part is adhesively fixed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber splicing method in which a pair of optical fibers are spliced together and the spliced portion is protected by a sleeve.

[0002]

2. Description of the Related Art The fusion splicing of optical fibers is carried out by removing the fiber coating on the splicing end and heating and melting the butt end of the exposed bare glass fiber. The fiber coating is removed, the splicing connection is made, and the bare fiber is exposed.
Protected and reinforced by protective members. This protective member is usually constructed by placing a reinforcing rod in a heat shrinkable sleeve that shrinks in the radial direction by heating and accommodating a heat meltable tube made of a heat meltable adhesive resin.

FIG. 5 is a view showing a conventional optical fiber connecting method, FIG. 5 (A) is a side sectional view in a state in which a fusion splicing portion is inserted through a protective member, and FIG. 5 (B) is protected. FIG. 5 (C) is an axial sectional view of FIG. 5 (A). In the figure, 1 is an optical fiber core wire, 2 is a coating removal portion, 3 is a fiber coating portion, 4 is a fusion splicing portion, 5 is a protective member, 6 is a heat shrinkable sleeve, 7 is a heat melting tube, and 8 is reinforcement. Indicates a stick.

The optical fiber core wire 1 (sometimes referred to as an optical fiber bare wire) is obtained by removing the fiber coating 3 at the connection end.
The ends of the coating removing portion 2 where the bare fiber is exposed are butted against each other, and fusion-spliced by arc discharge or the like. The protection member 5 has a length that covers a predetermined range of the fiber coating portions 3 on both sides of the coating removal portion 2, and a heat-melting tube 7 made of a hot-melt adhesive resin and a heat-melting tube 7 made of a hot-melt adhesive resin. A reinforcing rod 8 made of stainless steel or glass is housed.

The fusion-spliced optical fiber core wire 1 is inserted into the heat-fusible tube 7 so that the fusion-splicing portion 4 is located at the center and heated by a suitable heating means (not shown). It By this heating, the heat-fusible tube 7 is softened and melted, and the heat-shrinkable sleeve 6 is shrunk in the inner diameter direction.

The heat-meltable tube 7 that is heated and melted by the contraction of the heat-shrinkable sleeve 6 fills the space inside the heat-shrinkable sleeve 6 so as to cover the periphery of the coating removal portion 2 together with the reinforcing rod 8. When the heat-shrinkable sleeve 6 and the melted heat-meltable tube 7 are cured, as shown in FIG. 5 (B), the fusion spliced portion 4 including parts of the fiber coating portions 3 on both sides of the coating removal portion 2 is included. Is protected and reinforced over a predetermined range.

The protective member 5 has a different outer dimension depending on the removal length of the fiber coating portion 3 and the like.
In general, an outer diameter before shrinkage of 3.0 mm to 4.0 mm (thickness of about 0.2 mm) and a tube length of about 30 mm are used. The heat-fusible tube 7 has an outer diameter of 2.3 mm to 3.0 mm (thickness of about 0.3 mm).
The outer diameter of the reinforcing rod 8 is 1.0 mm to 1.
The thing of about 5 mm is used.

[0008]

As described above, the conventional protective structure for the fusion splicing portion has a length of about 30 mm and an outer diameter of about 3 mm.
mm, and a size having an outer shape comparable to that of a small optical component. Therefore, a relatively large space is required for routing and storing the optical wiring in the device, which is an obstacle to downsizing of the device. In addition, the weight of the optical fiber is larger than that of the optical fiber, and the core is easily damaged during handling, and the heating work time for reinforcement is longer than the fusion splicing time.

The outer diameter of the fiber coating is 0.24 mm
In the fusion splicing of the optical fiber core wire 1 of 0.4 mm, the fiber coating portion 3 is directly clamped by the holding member without holding the bare fiber portion, and the length of the coating removing portion 2 is 8.0 mm to
About 16.0 mm (4.0 mm-8.0 m on one side of the fiber)
m), a technique for high-strength connection has also been developed (see, for example, Japanese Patent Laid-Open No. 6-118251). in this case,
The tensile breaking strength of the fusion spliced portion can be increased by 1.5 or more as compared with the case of the ordinary splicing in which the bare fiber portion is placed on the V groove. Therefore, the tensile strength at break of the fusion splicing part is sufficient by itself, and it is not necessary to further increase it with the protective member.

By protecting and reinforcing the fusion splicing part of the optical fiber,
Even in the above high strength connection or normal connection,
It may be sufficient to have the ability to protect the bare fiber and prevent it from breaking due to bending. For example, an optical fiber is mounted in equipment such as information equipment or in an optical module, and the fusion splicing part used for connection between optical parts is different from the one used as an optical fiber line such as a communication cable. ,
No major physical stress.

Therefore, in the present invention, with respect to the use of an optical fiber in which a large physical stress does not occur, protection and reinforcement of the fusion splicing part are optimized with a minimum necessary configuration,
It is an object to realize a reduction in working time and a reduction in size, and to solve the conventional problems.

[0012]

According to the optical fiber connecting method of the present invention, a pair of optical fiber tips are removed by coating and are connected by fusion, and the fusion splicing portion and the coating removal portion are covered with a rigid sleeve. It is characterized by protecting.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram for explaining the basic mode of the present invention, FIG. 1 (A) shows a state before protecting a fusion splicing portion with a sleeve, and FIG. 1 (B) shows a fusion splicing portion with a sleeve. It is a figure which shows the state which was done. In the figure, 11 is an optical fiber core wire, 1
Reference numeral 2 is a coating removal portion, 13 is a fiber coating portion, 14 is a fusion splicing portion, and 15 is a sleeve.

The optical fiber core wire 11 (sometimes referred to as an optical fiber element wire) is a single layer or two layers with a fiber coating 13 being colorless or colored on the outer surface of a bare glass fiber having a nominal outer diameter of 0.125 mm. It was formed. When fusion-splicing a pair of optical fiber core wires 11, the fiber coating portion 13 at the connection end is removed to expose the bare fiber, and the end portion of the bare fiber is cut to form the coating removal portion 12 having a predetermined length. Form. The exposed bare fiber is placed at a connection end on a fusion splicer (not shown), and the ends thereof are butted against each other, and fused by discharge heating or the like to be spliced.

At the time of fusion splicing, an ordinary fusion splicing method in which the exposed bare fiber portion is placed on a V-groove and clamped for connection, and the tip portion of the fiber coating portion 13 is directly attached without gripping the bare fiber portion. There is a fusion splicing method which is called a high-strength connection in which clamping is performed. The latter high-strength connection does not grip the bare fiber portion, so the fiber coating 1
The removal length of 3 can be shortened, and since the bare fiber portion is not damaged, the tensile strength of the connection portion can be increased.

As shown in FIG. 1A, the sleeve 15 has one of the optical fiber core wires 11 before fusion splicing.
Insert it in. After the fusion splicing, as shown in FIG. 1B, the fusion splicing portion 14 and the coating removing portion 12 are slid so as to cover the whole, and an adhesive is applied to both ends to be fixed by adhesion.
The sleeve 15 is formed with a length having an overlap of about 2 mm to 6 mm on the fiber coating portions 13 on both sides of the coating removing portion 12, and the inner diameter is 0.3 mm to 0.5 mm which is slightly larger than the outer diameter of the optical fiber core wire 11. The outer diameter is preferably 1.0 mm or less. For example, when the fiber coating outer diameter of the optical fiber core wire 11 is 0.25 mm, the inner diameter is 0.2.
A sleeve having a diameter of 3 mm and an outer diameter of 0.5 mm is used.

The sleeve 15 may be made of a transparent or opaque hard resin material having various rigidity, or may be made of a metal material or a glass material. When using a transparent sleeve, an ultraviolet curing adhesive can be used. The sleeve made of metal can have a thin wall thickness and a smaller diameter. For example, when using a stainless steel sleeve, the inner diameter is 0.35.
Available in mm with an outer diameter of 0.45. Further, the glass sleeve can match the coefficient of thermal expansion with that of the glass of the optical fiber, and the reliability with respect to temperature change can be enhanced.

FIG. 2 is a view showing another embodiment, and shows an example of recoating the coating removing portion. 2A is a diagram showing a state before the fusion splicing portion is protected by the sleeve, and FIG. 2B is a diagram showing a state in which the fusion splicing portion is protected by the sleeve. In the figure, 16 indicates a coating material for recoating, and other reference numerals are the same as those in FIG.

The coating removing portions 12 on both sides of the fusion splicing portion 14
When the fiber coating is removed and the glass bare fiber is left as it is, the surface thereof is easily scratched and easily broken. After covering with the sleeve 15, the bare fiber surface of the coating removal portion is protected from external force,
At the stage of inserting the sleeve 15, it may come into contact with the sleeve 15. Therefore, it is preferable to apply the coating material 16 similar to the fiber coating to the coating removal portion 12 and recoat it. As the coating material 16 for recoating, it is desirable to use an ultraviolet curable resin similar to that for coating an optical fiber.

FIG. 3 is a diagram showing an example of adhesively fixing the sleeve. 3A is a diagram showing a state before the fusion splicing portion is protected by a sleeve, FIG. 3B is a diagram showing an example of applying an adhesive resin, and FIG. 3C is a diagram showing the fusion splicing portion. It is a figure which shows the state protected by the sleeve. In the figure, 17 indicates an adhesive resin, and other reference numerals are the same as those in FIG.

The sleeve 15 is adhered and fixed by sliding the sleeve 15 to a predetermined position as shown in FIG. 1 (B), applying an adhesive to both ends of the sleeve, and applying a capillary action to the overlapping portion with the fiber coating portion 13. It may be made to infiltrate, but it may be adhesively fixed by the method as shown in FIG. Figure 3
As shown in (A), one of the optical fiber core wires 11 is inserted before fusion splicing. After the fusion splicing, as shown in FIG. 3B, a predetermined amount of the adhesive resin 17 is applied to the fiber coating end of the optical fiber core wire 11 on the side where the sleeve 15 is inserted. After that, as shown in FIG. 3C, when the sleeve 15 is slid to the position of the coating removing portion 12, the adhesive resin 17 is applied to the inner surface of the sleeve 15 and can be adhesively fixed.

The adhesive resin preferably has flexibility after curing. When the sleeve 15 is firmly bonded and fixed to the optical fiber core wire 11, the reliability is higher even when vibration is applied to the device or the optical module. However, when the optical fiber core wire 11 and the sleeve 15 have different thermal expansion coefficients, if the adhesive fixation is strong, stress may be applied to the fusion splicing portion due to temperature change, and the transmission loss may increase. Therefore, by fixing the sleeve 15 with the adhesive resin having equality as described above, it is possible to alleviate the stress generation due to the difference in thermal expansion and suppress the increase in loss at the fusion splicing portion.

FIG. 4 is a view showing another embodiment of the adhesive fixing of the sleeve 15. In the example of FIG. 4, only one end side of the sleeve 15 is adhesively fixed. As described above, it is preferable that the sleeve 15 be firmly adhered and fixed to the optical fiber core wire 11, but stress may occur due to a difference in thermal expansion coefficient. However, the sleeve 15
By adhesively fixing only one end side and leaving the other end side free, it is possible to eliminate the occurrence of stress due to the difference in thermal expansion, and to prevent an increase in loss at the fusion spliced portion.

[0024]

As is apparent from the above description, according to the present invention, the protection / reinforcement structure of the fusion splicing part is greatly reduced in the use of the optical fiber which does not cause a large physical stress. In addition, it is possible to reduce the size, and it is possible to significantly reduce the working time because there is no need for heating or the like.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a basic mode of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing an example of a method for adhesively fixing a sleeve according to the present invention.

FIG. 4 is a diagram showing another example of the method for adhesively fixing a sleeve according to the present invention.

FIG. 5 is a diagram illustrating a conventional technique.

[Explanation of symbols]

11 ... Optical fiber core wire, 12 ... Coating removal part, 13 ... Fiber coating part, 14 ... Fusion splicing part, 15 ... Sleeve, 16
... Recoating material, 17 ... Adhesive resin.

Claims (7)

[Claims] 1. An optical fiber splicing method, characterized in that the coatings at the ends of a pair of optical fibers are removed and spliced together, and the fusion spliced portion and the coating stripped portion are covered with a rigid sleeve for protection. 2. The optical fiber connecting method according to claim 1, wherein the sleeve is made of a metal material. 3. The optical fiber connecting method according to claim 1, wherein the sleeve is made of a glass material. 4. The optical fiber splicing method according to claim 1, wherein the fusion splicing portion and the coating removal portion are coated with a coating material. 5. The sleeve is adhered and fixed with an adhesive resin having flexibility after curing.
5. The optical fiber connection method according to any one of 4 to 4. 6. The optical fiber connecting method according to claim 1, wherein the sleeve is bonded and fixed only at one end. 7. The thin sleeve having an outer diameter of 1 mm or less is used to protect the sleeve.
7. The optical fiber connection method according to any one of 6 to 6.