JPS6060607A - Formation of reinforced connection part of optical fiber - Google Patents

Abstract

PURPOSE:To eliminate the formation of foam in curing and prevent an increase in transmission loss by applying a curing accelerator to an optical fiber element wire connection part and surfaces of optical fiber element wires on both sides thereof, and injecting high polymer resin and curing the connection part. CONSTITUTION:Optical fiber cores 1 and 1' to be connected have coating layers 2 and 2' removed atop to expose element wires 3 and 3' to necessary length, and the tips of the element wires 3 and 3' are put in abutting relation to form the optical fiber element wire connection part 4 by arc welding. This connection part 4 and the surfaces of the element wires 3 and 3' on both sides thereof are coated with the curing accelerator, and those are stored in an element wire part storage groove 8 and coating part storage grooves 9 and 9' formed in the substrate 5 of a reinforcing member 7; and resin which cures by contacting the curing accelerator 12 is injected in said state and a cover 6 is closed. Thus, the confinement of foam in the resin is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a reinforced optical fiber connection portion in which an optical fiber connection portion is fixed to a reinforcing member using a polymer resin.

As shown in FIGS. 1 and 2, this type of conventional reinforced optical fiber connection section has optical fiber cores 1.1 to be connected.
The rooting layer 2.2' is removed at the tip of the optical fiber wire 3.3', and the optical fiber cable connection part 4 is formed by arc welding or the like with the tips of the optical fiber strands 3.3' abutted from inside. A reinforcing member 70 consisting of a substrate 5 and a lid 6, a strand accommodating groove 8 provided on the substrate 5, and coating section accommodating grooves 9, 9' continuous to both ends thereof.
The structure was such that it was contained together with Z silicone-based or epoxy-based polymer resin 10, and the lid 6 was closed and fixed by adhesive.

However, the optical 7-eyeper connection portion reinforced in this manner has the disadvantage that when temperature changes are applied, the transmission loss increases, and in severe cases, the optical fiber wire may break. The reason for this increase in transmission loss and breakage of the optical fiber is that air bubbles 11 exist in the polymer resin 10, as shown in Fig. 2, and stress is generated at the interface of the air bubbles 11 due to thermal strain caused by temperature changes. This is because the fibers are concentrated, and this causes strain to be applied to the fiber optic wire 3.3'. There are three reasons for the formation of bubbles 110: 0 ([3)] Occurs when the polymer resin is applied to the surface of the optical fiber.

(O occurs when the polymer resin hardens) Of these, the problem with 0 can be solved by vacuum degassing treatment of the polymer resin, and the problem with ω can be solved by keeping the surface of the optical fiber wire clean. This problem can be solved by devising a method for applying the polymer resin, but point (C) remains unresolved.

The following two mechanisms can be considered for the bubbles generated during the curing process of the polymer resin.

(a) Products generated during the curing reaction remain as bubbles.

(b) The hardening reaction does not proceed uniformly, and the part shown in Figure 6 (4) hardens into a shell shape first, and this hardened shell part 1
The uncured portion 10B is surrounded by the 0A, and as shown in FIG. 3 CB), the bubbles 11 are formed as shown in FIG. It occurs and becomes trapped.

For example, some silicone resins that are currently widely used as polymeric resins for reinforcing optical fibers react with moisture in the air (condensation reaction) to produce alcohol. There is a possibility that bubbles 11 may be generated. However, as a countermeasure for (a), it is sufficient to use an addition reaction type polymer resin that does not produce by-products.

An object of the present invention is to provide a method for forming a reinforced optical fiber connection part that can solve the problem of bubbles generated when a polymer (σ1 resin) is cured.

In the present invention, the coatings on the connection ends of both optical fiber core wires to be connected are removed to expose the respective optical fiber wires, and the optical fiber wires of both parties are butted and connected to each other to form an optical fiber element. Reinforcement in which a line connection part is formed, and the periphery of this optical fiber connection part and the optical fiber strands on both sides thereof are fixed to the reinforcement member with a polymer resin within a reinforcing member to form a reinforced optical fiber connection part. In the method for forming an attached optical fiber connection part, a curing accelerator is applied in advance to the surface of the optical fiber connection part and the optical fiber cable on both sides thereof, and then the polymer resin is injected or applied, The method is characterized in that the polymer resin is first cured from the surface side of the optical fiber (strands and their connecting parts).

Embodiments of the present invention will be described in detail below with reference to FIGS. 1, 4, and 5. As shown in FIG. The coating layers 2 and 2' are removed to expose the required length of the strands 3 and 3'.
The tips of these optical fibers (strands 3 and 3' are butted together to form a υ optical fiber connection part 4 by arc fusion etc.). A curing accelerator 12 is applied to the surface of the phyno wire 3.3'. As the curing accelerator 12, for example, an alcohol solution containing naphthenic acid conolte is used. Next, this curing accelerator 12 is applied. The optical fiber connecting portion 4 and the optical fiber wires 3 and 3' on both sides thereof are placed in a reinforcing member 70 and a fiber receiving sieve 8 and a stray portion receiving groove 9 provided on the substrate 5 as shown in FIG. , 9'.In this state, each groove 8, 9'
．． A resin that cures by contacting the curing accelerator 12 in the 9', and is a compound having a double bond within the molecule or at the end of the molecule, such as a peroxide such as methyl ethyl-peroxidonezoyl peroxide, tertiary methyl A two-component contact curing type polymer resin 10 such as a resin containing a compound that induces radical polymerization by generation of radicals such as benzoate or cyclohexanone peroxide is injected or coated to form the original fiber strand connection portion 4 and the optical fiber cable. The wires 3, 3' and the outer peripheries of the backing layers 2, 2' are coated as shown in FIG. 5, and the lid 6 is closed. In this state, the polymer resin 10 is coated.
When cured, a curing accelerator 12 is applied to the surface of the optical fiber connecting portion 4 and the optical fiber cables 3, 3' on both sides thereof.
Since the polymer resin 10 is coated, the polymer resin 10 starts to harden from the surface side of the optical fiber connecting portion 4 and the optical fiber strand 3.3'. Air bubbles 11 are not trapped in the polymer resin 10 near the surfaces of the optical fibers 3, 3', resulting in a cell-free polymer resin layer 10A as shown in FIG. The surface of the polymer resin 10 is adhered to the substrate 5 and the lid 6 of the reinforcing member 7.

When the bubble-free polymer resin layer 10A is formed in this manner, the transmission loss increases due to the bubbles 11 coming into contact with or close to the surface of the optical fiber connecting portion 4 and each optical fiber strand 3, 3'. And breakage of the optical fiber wire 3.3' can be prevented.

As explained above, in the method for forming a reinforced optical fiber connection part according to the present invention, a curing accelerator is applied in advance to the surface of the optical fiber connection part and the optical fiber strands on both sides thereof, and then the polymer Since the resin is injected or coated, it is possible to start curing the polymer resin from the surface side of the optical fiber wire connection portion and the optical fiber wire. Also, air bubbles are not trapped on the surface of the optical fiber, and a bubble-free polymer resin layer can be formed. Therefore, according to the reinforced optical fiber connection section formed by the method of the present invention, air bubbles do not come into contact with or come close to the surface of the optical fiber connection section and the optical fiber strands on both sides thereof, and there are no air bubbles. The polymer resin layer acts as a buffer layer against stress caused by bubbles, and can prevent an increase in transmission loss and breakage of the optical fiber due to bubbles.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a reinforcing optical fiber connection part in the middle of assembly, and Fig. 2 is a vertical cross-section showing the state in which gastric molecular resin covers the optical fiber and its connection part in a conventional reinforced optical fiber connection part. 3 (A) ω) (C) are explanatory diagrams showing the process of trapping air bubbles in the polymer resin; FIG. 4 is a perspective view of the curing accelerator application step in the method of the present invention; FIG. 5 is a longitudinal cross-sectional view showing an example of the coating state of the polymer resin on the optical fiber wire and its connection portion in the reinforced optical fiber connection portion formed by the method of the present invention. Optical fiber wire, 4... Optical fiber wire connection portion, 5... Substrate, 6... Lid, 7... Reinforcement member, 8... Strand wire portion accommodation groove, 9.9'. ... Covering part accommodation groove, 1o... Polymer resin, 10A... Cell-free polymer resin layer, 11... Air bubbles, 12... Curing accelerator.

Claims (1)

[Claims] The coatings on the connection ends of both optical fiber core wires to be connected are removed to expose the respective optical fiber wires, and the fiber wires of both parties are butted and connected to each other to form an optical fiber cable connection portion. A reinforced optical fiber connection is formed by forming a reinforced optical fiber connecting portion and fixing the periphery of the optical fiber wire on both sides thereof to the reinforcing member with a polymer resin within a reinforcing member to form a reinforced optical fiber connecting portion. In the method for forming a part, a curing accelerator is applied in advance to the optical fiber connecting part and the surface of the optical fiber on both sides thereof, and then the polymer resin is injected or applied. A method for forming a reinforced optical fiber connection part, characterized in that the above-mentioned optical fiber strand and its connection part are first hardened from the surface side.