JPS5965802A - Lead-in structure of optical fiber - Google Patents

Abstract

PURPOSE:To obtain a lead-in part having good water- and air-tightness without spoiling an ptical transmission characteristic by inserting an optical fiber which is filled with a viscous material between a strand and a covering without striping the covering into the through-hole of a sleeve into which the optical fiber is passed and fixing the same by an adhesive or the like. CONSTITUTION:An optical fiber filled with a viscous material having viscosity, chemical stability and low gas permeability such as polyisobutyrene in the space between a silicone resin covering 9 and an optical fiber strand 8 and in the space between the covering 9 and a nylon covering 10 is fixed and sealed into the through-hole of a sleeve 6 in an optical fiber lead-in part of an optical submarine repeater or the like by using an epoxy adhesive 11 in the space between the inside wall of the through-hole and the fiber in the stage of inserting said fiber into said lead-in part. The higher water- and air-tightness is maintained if a through-hole tapered on the outside is provided like a sleeve 12 and a self- sealing effect is provided by the water pressure from the outside. The lead-in part having high reliability is thus constituted without stripping the covering and without deteriorating the characteristic of the strand 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber (introduction structure) such as an optical submarine repeater.

The optical submarine repeater consists of a circuit unit l shown in Figure 1.
is housed in the pressure-resistant cylinder 2, and the pressure-resistant cover 3 is equipped with an optical fiber (-3) installed at both ends of the pressure-resistant cylinder 2. An optical fiber introducing section 5 is provided.

An example of a conventional structure of the optical fiber introducing section 5 is shown in FIG.

That is, the coating of the optical fiber 4 is peeled off over a certain length μ, and the strands are exposed. Then, the optical fiber 4 is inserted into the through hole of the sleeve 6, and the part where the strand is exposed is sealed with an adhesive 7 such as epoxy.
’ structure.

In general, optical fibers have improved optical loss characteristics at low temperatures,
The structure between the strands and the sheathing is loose for the purpose of "workability during connection work." For this reason, a high degree of watertightness,
If you require airtightness, please refer to the above. There is peace of mind in sealing the wires with them exposed. However, if the bare wire is exposed, the coating that originally protects the wire from stress is peeled off and is discontinuous, so this part may be exposed to temperature recycling, water pressure, etc. When the elliss stress is applied n, there is a tendency for slight bending to occur in the wire. In order to prevent the occurrence of minute bends in the strands, sufficient consideration must be given to the selection of the adhesive 7.

Furthermore, due to peeling of the coating, the tensile strength of this portion decreases to about 1/2 of that of a normal optical fiber. This decrease in tensile strength and the occurrence of the above-mentioned slight bending may cause a risk of breakage in the worst case. These are obstacles to realizing a highly reliable optical fiber introduction section. Furthermore, coating removal work 1
The assembly work requires great care and high skill to prevent the exposed wires from breaking, and there are many problems such as difficulty in mass production, and improvements are desired.

An object of the present invention is to solve the above-mentioned conventional drawbacks and provide a highly reliable optical fiber introduction structure.

The introduction structure of the present invention is an optical fiber introduction structure of a repeater housing, in which an optical fiber is filled with a viscous substance in the gap between the wire and the coating, and a rLfc sleeve is provided with a through hole for passing the optical fiber. The optical fiber is inserted into the through hole of the sleeve and fixed and sealed with an adhesive or the like.

Next, the present invention will be explained in detail with reference to the drawings]-
Ru.

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

That is, the strand part 8 of the optical fiber is covered with the silicone resin coating M9 and the nylon coating layer 10, and the gap between the strand part 8 and the silicone resin coating layer 9 and the gap between the silicone resin coating layer 9 and the nylon coating layer 10 is is filled with polyimbutylene of appropriate viscosity. Polyisobutylene is chemically stable, has low gas permeability, and has a suitable viscosity. Therefore, the wire portion 8. A-layer 9
．． No. 10 has axial water-tightness and airtightness while maintaining a mechanically loose bond. That is, even when water pressure is applied, the flow resistance of polyisobutylene prevents water from entering, and the airtightness is maintained. The optical fiber is inserted into the through hole of the sleeve 6, and the gap between the nylon coating layer 10 and the inner wall of the sleeve 6 is firmly sealed with adhesive LiK, thereby obtaining an optical fiber introduction structure with high watertightness and airtightness.

In this example, the optical fiber can be sealed without stripping the coating and without destroying the basic structure of the optical fiber.
Even when stress due to temperature cycles or water pressure is applied, bending does not occur in the wire portion 8. Therefore, there is an effect that characteristic deterioration such as an increase in optical loss does not occur. Also,
Improved workability and reliability can be achieved without reducing the tensile strength of the optical fiber. Furthermore, the thickness of the adhesive 11 can be made thinner than in conventional structures, which has the advantage that peeling of the adhesive from the book due to stress application or the like is less likely to occur.

FIG. 4 is a sectional view showing a second embodiment of the invention.

In this case, a through hole with a groove is bored in the sleeve 12, and the wire portion 8. Silicone resin coating 9
．． The optical fiber integrated with the nylon coating layer 10 is inserted into the through hole as it is, and the through hole is filled with an adhesive 11 such as epoxy [-1 assimilated. Of course, the strand part 8. Covered part 9. The gaps between the IO are filled with polyisobutylene.

In this embodiment, the hole through hole and the adhesive hole are
KJ: So, when water pressure is applied from the outside, a self-sealing effect occurs, which further improves reliability.

The above-mentioned examples are all examples in which the through hole of the sleeve 60 is sealed with an adhesive, but the through hole may be sealed by injection molding of a material equivalent to the nylon coating 10, for example, instead of being filled with adhesive. , it may be fixed to the sleeve 6.

As described above, in the present invention, an optical fiber filled with a viscous substance is inserted into a sleeve between the wire coatings,
Since the structure is such that the gap between the optical fiber coating and the inner wall of the sleeve is fixedly sealed with an adhesive or the like, the work is easy and high reliability can be obtained. Of course, it can also be applied to an optical fiber introduction structure for electronic equipment other than optical submarine repeaters.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of an optical submarine repeater, FIG. 2 is a sectional view showing an example of a conventional optical fiber introduction structure, and FIG. 3 is a sectional view showing a first embodiment of the present invention. FIG. 4 is a sectional view showing a second embodiment of the present invention. In the figure, 1... circuit unit, 2... pressure resistant cylinder, 3... pressure resistant cover, 4... optical fiber, 5...
...Optical fiber introduction part, 6.12...Sleeve, 7
, 11... Adhesive, 8... Wire portion, 9... Silicone resin coating layer, 10... Nylon coating layer. Agent: Patent attorney Toshimune Sumita

Claims (1)

[Claims] The optical fiber introduction structure of the repeater housing includes an optical fiber in which a gap between the strands and the coating is filled with a viscous substance, and a sleeve in which a through hole is drilled to allow the optical fiber to pass through. An optical fiber introduction structure characterized in that the optical fiber is inserted into a through hole and fixedly sealed with an adhesive or the like.