JP2004045663A - Optical fiber connecting sleeve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable optical fiber connecting sleeve with excellent workability at a low cost. <P>SOLUTION: A tapered fiber insertion port 22 is provided on each of the end faces of a sleeve 20 and the cross section of a connection hole is turned to a polygonal shape. The center lines of the connection hole of a large diameter provided on the side of the end face of the sleeve 20 and the connection hole of a small diameter provided on the center part of the sleeve are on the same straight line as the center of the fiber insertion port 22 and an adhesive material 21 is filled in the connection hole. Optical fibers 23 and 24 are sealed at the fiber insertion port 22 with the excess portion of the adhesive material 21 discharged by inserting the optical fibers 23 and 24 in the connection hole and the optical fibers 23 and 24 are connected and fixed in the connection hole with the remaining portion of the adhesive material 21. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical fiber connection sleeve, and more particularly, to an optical fiber connection sleeve that is low in cost, has excellent workability, and has high reliability.
[0002]
[Prior art]
In the laying of the optical fiber cable, for example, a technique of laying a 2 km cable for each section and connecting the corresponding optical fibers of the cables in both sections using a connection box called a closure is adopted. In this method, when laying a cable that carries long distance transmission, the number of optical fiber connections becomes enormous, so the optical fiber connection accuracy is increased, the number of connection steps is reduced, and low cost and durability reliability are achieved. It is necessary to realize a high optical fiber connection.
[0003]
As a conventional optical fiber connection method, a fusion splicing method in which an optical fiber is melted and heated, a “mechanical price method” in which an optical fiber is mechanically fixed in a connection container, a transparent sleeve or a transparent lid are used. An "adhesive splice method" in which optical fibers are butted with a V-groove portion and fixed with an ultraviolet-curing adhesive is known. In Japan, a fusion splicing method is mainly used.
[0004]
[Problems to be solved by the invention]
However, in the fusion splicing method, an expensive optical fiber fusion splicing device is required and the cost is increased. In addition, since the fusion splicing device is a relatively large device, it is required to be used in a narrow place. The connection operation becomes difficult, and further, there is a problem that an extra length for setting the optical fiber in the fusion splicing apparatus and an extra length for reconnection are required assuming that the connection fails.
[0005]
In the mechanical splice method, the connection tool is relatively inexpensive, but the mechanical splice container as the connection member is expensive and the cost per unit connection is high, and the optical fiber is fixed only by mechanical tightening. Therefore, there is a problem that the durability reliability is inferior.
[0006]
Furthermore, the connection splice method has a problem that workability at a connection work site is poor.
[0007]
The present invention has been made in view of such a problem, and an object of the present invention is to provide an optical fiber connection sleeve that is low in cost, has excellent workability, and has high reliability.
[0008]
[Means for Solving the Problems]
In order to achieve such an object, the present invention provides an optical fiber connection sleeve for butt-connecting two optical fibers in a connection hole penetrating both end faces. Each of the sleeve end faces has a tapered fiber insertion port, and the connection hole is formed such that the center line of the first connection hole provided on the sleeve end face side and the center line of the second connection hole provided on the central portion of the sleeve. The first connection hole and the second connection hole have a substantially polygonal cross-sectional shape, and are provided with an adhesive in advance. Is filled, and the optical fiber is sealed at the fiber insertion port by an excess portion of the adhesive discharged by the optical fiber inserted into the connection hole, and the remaining portion of the adhesive is used to seal the optical fiber. Optical fiber Characterized in that it is connected fixed in serial connection hole.
[0009]
According to a second aspect of the present invention, in the optical fiber connection sleeve according to the first aspect, the optical fiber connection sleeve further includes a reinforcing member extending in a direction substantially parallel to the connection hole.
[0010]
According to a third aspect of the present invention, in the optical fiber connection sleeve according to the first or second aspect, the adhesive is made of any one of plastic, glass, and zirconia that transmits visible light. It is a visible light curable adhesive having a viscosity of 10,000 cP or more or a gel.
[0011]
According to a fourth aspect of the present invention, in the optical fiber connection sleeve according to the first or second aspect, the adhesive is made of plastic or glass that transmits ultraviolet light, and the adhesive has a viscosity of 10,000 cP or more or a gel. Characterized in that it is an ultraviolet curable adhesive.
[0012]
The invention according to claim 5 is the optical fiber connection sleeve according to claim 1, wherein the adhesive is made of invariable steel, and the adhesive is a thermosetting adhesive having a viscosity of 10,000 cP or more or a gel. There is a feature.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0014]
FIG. 1 is a cross-sectional view for explaining the configuration of an optical fiber connection sleeve of the present invention. The outer shape of this sleeve 10 is, for example, substantially columnar, and a substantially central portion has a diameter for connecting an optical fiber. Different connection holes 11 and 12 are provided, and a tapered fiber insertion port 13 is provided on an end face of the sleeve 10. The connection holes 11 and 12 are pre-filled with an adhesive, and the large-diameter connection hole 11 and the small-diameter connection hole 12 are each one distance less than the outer diameter of the coated portion of the optical fiber and the bare portion of the optical fiber. It has a size capable of drawing an inscribed circle larger by about 2 μm, and preferably has a polygonal cross section. The fiber insertion ports 13 at both ends are tapered so that the optical fiber can be easily inserted, and the adhesive discharged when the optical fiber is inserted into the connection holes 11 and 12 sufficiently fills the fillet. The shape can be formed.
[0015]
FIG. 2 is a view for explaining a state in which an optical fiber is being connected to the optical fiber connection sleeve. The connection hole of the sleeve 20 is filled with an adhesive 21, and both ends of the sleeve 20 are provided. An optical fiber is inserted from the provided tapered fiber insertion port 22, and the optical fiber is cut by the adhesive 21 (excess part) discharged to the fiber insertion port 22 when the optical fiber is inserted into the connection hole. While sealing at the insertion port 22, the end faces of the bare optical fiber 24 at the tip of the optical fiber coating 23 are abutted and fixed in the connection hole by the adhesive 21 remaining in the connection hole.
[0016]
The adhesive 21 is not less than 10,000 cP to prevent the adhesive 21 from flowing out of the sleeve 20 before abutting the optical fibers in a state where the optical fiber is filled in advance, or to be easily dispersed at the stage of inserting the optical fibers. Alternatively, the viscosity is adjusted to a gel-like viscosity. When plastic, glass, or zirconia that transmits visible light is used as the material of the sleeve 20, the adhesive is cured by visible light curing. When plastic or glass that transmits ultraviolet light is used, the adhesive can be cured by ultraviolet curing. Further, in the case of the invariable steel, a thermosetting adhesive having a viscosity of 10,000 cP or more or a gel is used.
[0017]
FIG. 3 is a cross-sectional view of the optical fiber connection sleeve of the present invention having a triangular inner cross section. As the optical fiber 32 is inserted into the connection hole of the sleeve 30 filled with the adhesive 31, the optical fiber is inserted. The excess adhesive 31 that has been inserted due to the insertion of the adhesive 32 gradually moves to both end surfaces of the sleeve through the connection holes having the triangular cross section, and finally, the tapered optical fiber insertion openings at both ends. And the sleeve 30 and the optical fiber 32 are fixedly sealed.
[0018]
FIG. 4 is a view for explaining an example of the cross-sectional shape of the central portion of the optical fiber connection sleeve of the present invention, and the cross-sectional shape of the connection holes 42, 44, 46 formed in the central portions of the sleeves 41, 43, 45. However, FIG. 4A shows an example of a triangle, FIG. 4B shows an example of a square, and FIG. 4C shows an example of a hexagon. One of the reasons why the cross-sectional shape is polygonal is that the excess adhesive passes through a gap formed between the inner wall of the sleeve and the inserted optical fiber, and an optical fiber insertion port at the end face of the sleeve. This is because when the sleeve is processed by injection molding or the like, the effect of increasing the strength of the inner diameter pin can be expected as compared with a circular cross section. In addition, if an appropriate round is provided at the inner angle of the polygonal diameter, the adhesive is more easily discharged, which is effective in stabilizing the strength of the inner diameter pin.
[0019]
In the case where the material of the optical fiber connection sleeve of the present invention is plastic, glass, or the like, in order to improve the strength of the sleeve, it is configured to incorporate a reinforcing material or package the outside with a heat-shrinkable tube. A configuration is also possible.
[0020]
FIG. 5 is a view for explaining the configuration of the optical fiber connecting sleeve of the present invention having a reinforcing rod therein. The basic structure of this sleeve 50 is similar to that of the sleeve shown in FIG. Connection holes 51 and 52 having different diameters for connection and a tapered fiber insertion port are provided, and a reinforcing material 55 extending in a direction substantially parallel to the connection holes 51 and 52 is provided near the outer periphery of the sleeve 50. It is configured to be able to maintain sufficient strength by being embedded.
[0021]
Hereinafter, the optical fiber connection sleeve of the present invention will be described more specifically based on examples, but it is needless to say that the present invention is not limited to these examples.
[0022]
(Example 1)
In order to connect and fix a single mode optical fiber having an outer diameter of 0.125 mmφ, zirconia is used, and the shape shown in FIG. 1 and FIG. 4A is obtained by injection molding and polishing, and has an outer diameter of 4 mm and a length of 30 mm. Created a sleeve. The connection hole at the center where the fiber is connected and fixed has a triangular cross-sectional shape with a diameter of an inscribed circle of 0.127 mmφ. The connection hole has a visible light curable type whose viscosity is adjusted to 20,000 cP. Acrylic adhesive is filled.
[0023]
Optical fibers are inserted from the tapered optical fiber insertion ports at both ends of the sleeve, butted at the center of the sleeve, and an excess portion of the adhesive generated with the insertion of the optical fiber is inserted into the optical fiber insertion port through the gap of the connection hole. To form a fillet between the optical fiber and the sleeve. In this state, the adhesive was cured and fixed by irradiating light for about 120 seconds using a visible light source such as a halogen or xenon lamp.
[0024]
The connection loss of the single mode optical fiber thus obtained was 0.03 dB or less at a wavelength of 1.5 μm. Further, the light loss fluctuation of the optical fiber connection part in the temperature cycle test at -20 to + 60 ° C was 0.2 dB or less. Further, the tensile strength of the optical fiber connection portion was 2 kg, and the tensile strength after immersion in water at 60 ° C. for 2 weeks also maintained 2 kg.
[0025]
(Example 2)
In order to connect and fix a single mode optical fiber having an outer diameter of 0.125 mmφ, quartz glass is used, and the shape shown in FIG. 1 and FIG. Created a sleeve. The connection hole in the center where the fiber is connected and fixed has a triangular cross-sectional shape with an inscribed circle diameter of 0.127 mmφ, and the connection hole has an ultraviolet light curing type viscosity adjusted to 20,000 cP. Acrylic adhesive is filled.
[0026]
Optical fibers are inserted from the tapered optical fiber insertion ports at both ends of the sleeve, butted at the center of the sleeve, and an excess portion of the adhesive generated with the insertion of the optical fiber is inserted into the optical fiber insertion port through the gap of the connection hole. To form a fillet between the optical fiber and the sleeve. In this state, the adhesive was cured and fixed by irradiating it with ultraviolet light having a light amount of 100 mW / cm ² for about 60 seconds. Further, in order to reinforce the quartz glass connection sleeve, a stainless steel rod of 1 mmφ was embedded and bonded as a reinforcing material, and the outside was packaged with a heat-shrinkable tube.
[0027]
The connection loss of the single mode optical fiber thus obtained was 0.03 dB or less at a wavelength of 1.5 μm. Further, the light loss fluctuation of the optical fiber connection part in the temperature cycle test at −20 to + 60 ° C. was 0.2 dB or less. Further, the tensile strength of the optical fiber connection portion was 2 kg, and the tensile strength after immersion in water at 60 ° C. for 2 weeks also maintained 2 kg.
[0028]
(Example 3)
In order to connect and fix a single mode optical fiber having an outer diameter of 0.125 mmφ, invariable steel (linear) having a linear expansion coefficient of 6 × 10 ⁻⁷ / ° C. is used, and powder molding is performed as shown in FIGS. 1 and 4 (a). A sleeve having an outer diameter of 4 mm and a length of 30 mm was prepared in the shape shown. The connection hole at the center where the fiber is connected and fixed has a triangular cross section with a diameter of an inscribed circle of 0.127 mmφ. The connection hole has a thermosetting epoxy whose viscosity is adjusted to 20,000 cP. System adhesive is filled.
[0029]
Optical fibers are inserted from the tapered optical fiber insertion ports at both ends of the sleeve, butted at the center of the sleeve, and an excess portion of the adhesive generated with the insertion of the optical fiber is inserted into the optical fiber insertion port through the gap of the connection hole. To form a fillet between the optical fiber and the sleeve. In this state, heating was performed at 120 ° C. for about 2 minutes to cure and fix the adhesive.
[0030]
The connection loss of the single mode optical fiber thus obtained was 0.03 dB or less at a wavelength of 1.5 μm. Further, the light loss fluctuation of the optical fiber connection part in the temperature cycle test at −20 to + 60 ° C. was 0.2 dB or less. Further, the tensile strength of the optical fiber connection portion was 2 kg, and the tensile strength after immersion in water at 60 ° C. for 2 weeks also maintained 2 kg.
[0031]
【The invention's effect】
As described above, according to the present invention, a tapered fiber insertion port is provided on each of the sleeve end faces, the cross section of the connection hole is made polygonal, and the large diameter connection hole provided on the sleeve end face side and the sleeve center are provided. The center line of the small diameter connection hole provided in the portion is provided so as to be on the same straight line as the center of the fiber insertion port, the connection hole is filled with an adhesive in advance, and the optical fiber is inserted into the connection hole. The optical fiber is sealed at the fiber insertion port with the surplus part of the adhesive discharged, and the optical fiber is connected and fixed in the connection hole by the remaining part of the adhesive. It is possible to provide a highly reliable optical fiber connection sleeve with high reliability.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view for explaining a configuration of an optical fiber connection sleeve of the present invention.
FIG. 2 is a diagram for explaining how an optical fiber is connected to an optical fiber connection sleeve of the present invention.
FIG. 3 is a sectional view of the optical fiber connection sleeve of the present invention having a triangular inner cross section.
FIGS. 4A and 4B are diagrams for explaining examples of the cross-sectional shape of the central portion of the optical fiber connection sleeve of the present invention, wherein FIG. 4A is a triangular shape, FIG. Is shown.
FIG. 5 is a view for explaining a configuration of an optical fiber connection sleeve of the present invention having a reinforcing rod therein.
[Explanation of symbols]
10, 20, 30, 41, 43, 45, 50 Sleeve 11, 12, 42, 44, 46, 51, 52 Connection hole 13, 22 Fiber insertion port 21, 31 Adhesive 23 Optical fiber coating 24 Optical fiber bare 32, 53, 54 Optical fiber 55 Reinforcing material

Claims (5)

An optical fiber connection sleeve for butt-connecting two optical fibers in a connection hole penetrating both end faces,
Each of the sleeve end faces has a tapered fiber insertion port,
The connection hole is provided such that the center line of the first connection hole provided on the end face side of the sleeve and the center line of the second connection hole provided on the central portion of the sleeve are on the same straight line as the center of the fiber insertion port. And
The cross-sectional shape of the first connection hole and the second connection hole has a substantially polygonal shape,
The connection hole is filled with an adhesive in advance,
The optical fiber is sealed at the fiber insertion port by an excess portion of the adhesive discharged by the optical fiber inserted into the connection hole, and the optical fiber is sealed by the remaining portion of the adhesive. An optical fiber connecting sleeve fixed inside the optical fiber connecting sleeve. The optical fiber connection sleeve according to claim 1, further comprising a reinforcing member extending in a direction substantially parallel to the connection hole. Visible light, plastic, glass or zirconia any material,
3. The optical fiber connection sleeve according to claim 1, wherein the adhesive is a visible light curable adhesive having a viscosity of 10,000 cP or more or a gel. Made of plastic or glass that transmits ultraviolet light,
3. The optical fiber connection sleeve according to claim 1, wherein the adhesive is an ultraviolet curable adhesive having a viscosity of 10,000 cP or more or a gel. Made of invariable steel,
The optical fiber connection sleeve according to claim 1, wherein the adhesive is a thermosetting adhesive having a viscosity of 10,000 cP or more or a gel.

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