JPH04208903A - Structure for reinforcing optical fiber spliced part - Google Patents

Abstract

PURPOSE:To unnecessitate the fixing of a spliced part on other structure at the time of wiring and to facilitate wiring work by coating the outsides of the exposed clads of optical fibers and the outsides of ends of the plastic coats with a carbon coating film. CONSTITUTION:The plastic coat 13 of an end of an optical fiber 1 is peeled off by about 15mm to expose the clad 12. The plastic coat 23 of an end of other optical fiber 2 is also peeled off by about 15mm to expose the clad 22. The tips of a pair of the fibers 1, 2 are brought into contact with each other and melt-stuck by arc discharge to splice the fibers together. The outsides of the exposed clads 12, 22 with the melt-stuck tips 6 and the outsides of ends of the plastic coats 13, 23 are then coated with a carbon coating film 40 of about 0.05-0.1mum thickness. This film 40 is deposited by setting the spliced part 5 in a thermal decomposition furnace, feeding gaseous hydrocarbon into the furnace and carrying out heating.

Description

[Detailed description of the invention]

[00011

FIELD OF THE INVENTION The present invention relates to a reinforcing structure for an optical fiber splice. The optical fiber is made using the internal CVD method. An optical fiber base material is formed by an external CVD method or the like, and this optical fiber base material is spun to form a core 11. as shown in FIG. A core wire having a glass cladding 12 having a refractive index smaller than the refractive index of the core is provided on the outer peripheral surface of the core 11, and a plastic coat 13 such as urethane resin, epoxy resin, or nylon resin is applied to the core wire, and the outer peripheral surface is The optical fiber 1 has a diameter d of 0.9 mm. [0002] This optical fiber is required for connection between optical components within an optical transmission device, and for connection between an optical transmission device and an optical cable of a line. Specifically, about 15 mm of the plastic coat 13 at the end of the optical fiber 1 is peeled off to expose the cladding 12, and about 15 mm of the plastic coat 23 at the end of the other optical fiber 2 is also peeled off. to expose the cladding 22. [0003] Then, with the end surfaces of the pair of optical fibers 1.2 in contact with each other, they are fused by arc discharge, and the abutting surfaces are used as the fusion surfaces 6 for splicing. therefore,
The length B of the splice portion 5 from which the plastic coat has been peeled off is about 30 Inm. [0004] By the way, since the splice part is affected by heat or the cladding is exposed, minute scratches are likely to be generated and the strength life will be reduced. Further, when bending stress is applied to the splice portion when wiring an optical fiber, the splice portion will break at or near the fusion surface 6. [0005] Therefore, it is necessary to reinforce the splice portion. [0006] FIG. 4 shows a conventional reinforcing structure for an optical fiber splice. In FIG. 4, a pair of optical fibers 1.2 is made by fitting a hot-melt resin tube such as ethylene vinyl acetate copolymer into the splice portion 5, and then cross-linking the plastic coat 13, 23 on both sides with a tube made of 9 stainless steel or the like. A hard core material 31 having a length of about 60 mm is placed along the core material, and a heat shrinkable tube 30 such as low density polyethylene or the like having a length longer than the hard core material 31 is fitted on the outside thereof. [0007] By heating the heat-shrinkable tube 30 from the outside, the hot-melt resin tube is melted and the heat-shrinkable tube 30 is shrunk. Due to these two steps, the hot melt resin tube is cured in a compressed state to become a hot melt resin 33, which is filled into the heat shrinkable tube 30. [0008] That is, since the hot melt resin 33 adheres to the splice portion 5 and the entire outer periphery of the plastic coat 13.23 and covers the splice portion 5, the splice portion 5 does not come into contact with external moisture and prevents the growth of minute scratches. do. [0009] Furthermore, since both ends of the hard core material 31 are fixed to the plastic coat, the splice portion 5 will not break due to external force or changes in humidity. [00101

[Problems to be Solved by the Invention] By the way, the dimensions of the reinforcing part of the splice part mentioned above are as shown in FIG. Therefore, when the optical fiber is wired, this reinforcing portion acts as a weight load on the optical fiber. [0011] Therefore, there is a problem in that the reinforcing portion must be fixed to the structure so that the weight of the optical fiber does not become a load when wiring the optical fiber. In addition, when the reinforcing part is fixed to a structure and a lateral tensile force is applied to the optical fiber, bending stress concentrates on the part of the optical fiber corresponding to the end of the hard core material, causing the optical fiber to bend. There was a risk of it breaking. [0012] The present invention was created in view of the above points, and provides a reinforcing structure for the splice part that does not require fixing the splice part to other structures when wiring optical fibers and facilitates wiring work. is intended to provide. [0013] [Means for Solving the Problems] In order to achieve the above object, the present invention provides a cladding 12.2 as illustrated in FIG.
With the end surfaces of the pair of exposed optical fibers 1 and 2 in contact with each other, the outer peripheral surface of the cladding 12.22 and the plastic coat 13.2 are connected at the splice portion 5, which is fusion-spliced.
The outer peripheral surface of the terminal of No. 3 is coated with a carbon film 40. [0014] Furthermore, as illustrated in FIG. 2, the outer periphery of the carbon film 40 is further covered with an ultraviolet curing resin 45. [0015]

[Operation] The carbon film 40 adhered and formed on the outer peripheral surface of the above-mentioned cladding and plastic coat has a film thickness of 0.1
Although it is on the order of micrometers, the dense and strong film adheres closely to the cladding, preventing moisture from entering and deteriorating the strength of the optical fiber. [0016] Therefore, the fatigue coefficient of an optical fiber coated with a carbon film, which is a measure of bending strength, is about 10 times the fatigue coefficient of a known optical fiber with an exposed cladding. [0017] That is, no special consideration is required for the splice portion when wiring the optical fiber. Further, by covering the surface of the carbon film 40 with an ultraviolet curable resin, the carbon film is prevented from being damaged during handling, and the strength is improved. [0018]

EXAMPLES The present invention will be specifically explained below with reference to FIGS. 11 and 2. Note that the same reference numerals indicate the same objects throughout the figures. [00191 FIG. 1 is a sectional view of the invention of claim 1,
FIG. 2 is a sectional view of the invention according to claim 2. In FIG. 1, approximately 15 mm of the plastic coat 13 at the end of the optical fiber 1 is peeled off to expose the cladding 12, and about 15 mm of the plastic coat 23 at the end of the other optical fiber 2 is also peeled off. The cladding 22 is exposed and the end surfaces of the pair of optical fibers 1 and 2 are brought into contact with each other, and the fibers are fused by arc discharge, and the abutting surfaces are used as the fused surfaces 6 for splicing. [00201 And the cladding 12.2 including the fusion surface 6
The outer circumferential surface of 2 and the outer circumferential surface of the end of the plastic coat 13.23 are coated with a carbon film 40. This carbon film 40 is formed on the outer circumferential surface of the cladding and the outer circumferential surface of the end of the plastic coat by inserting and setting the splice part 5 into a pyrolysis reactor, feeding hydrocarbon gas into the pyrolysis reactor, and heating it. , 0.05 μm ~ 0.17
A carbon layer with a thickness of about 1 m is deposited and attached. [00211 In FIG. 2, the outer periphery of the carbon film 40 is further covered with an ultraviolet curing resin 45 such as an epoxy resin or a urethane resin. This ultraviolet curing resin 4
The outer diameter of the optical fiber 5 is larger than the outer diameter of the plastic coat of the optical fiber, for example, about 1.5 mm. [0022] The ultraviolet curable resin 45 is prepared by placing the splice part 5 in a molten ultraviolet curable resin crucible with a die, pulling out the optical fiber through the die hole, and irradiating it with ultraviolet rays, in accordance with the formation of the plastic coat of the optical fiber. is formed. [0023]

As explained above, the present invention provides the following effects by reinforcing the optical fiber splice portion with a carbon film and further reinforcing it with an ultraviolet curable resin. [0024] Preventing the splice portion of the optical fiber from being damaged or bending the splice portion at an acute angle,
The lifespan of the optical fiber is improved and the transmission characteristics are guaranteed. Further, when wiring the optical fiber, there is no need to fix the splice portion to another structure, making the wiring work easier and the wiring space significantly reduced.

[Brief explanation of the drawing]

[Fig. 1] Cross-sectional view of the invention of claim 1

[Fig. 2] Cross-sectional view of the invention of claim 2

[Figure 3] Cross-sectional view of the splice part of the optical fiber

[Figure 4]
Cross-sectional view of conventional example

[Explanation of symbols]

1.2 Optical fiber, 5 Splice part, 6
Fusion surface, 11.21 Core, 12.22
Clad, 30 Heat shrink tube, 31
Hard core material, 33 Hot melt resin, 40 Carbon film, 45 Ultraviolet curing resin, 13.23
plastic coat,

[Figure 3]

Claims (2)

[Claims] Claim 1: At a splice part (5) in which the end surfaces of a pair of optical fibers (1, 2) with their respective claddings (12, 22) exposed are fused and spliced while in contact with each other, the cladding (12, 22) is fused and spliced. 12, 22) and the outer peripheral surface of the ends of the plastic coats (13, 23) are coated with a carbon film (40
) A reinforcing structure for the optical fiber splice portion, characterized by being coated with 2. A reinforcing structure for an optical fiber splice portion, characterized in that the carbon film (40) according to claim 1 is further covered with an ultraviolet curing resin (45).