JPS5939747A - Manufacture of high-strength optical fiber - Google Patents

Abstract

PURPOSE:To obtain an optical fiber having superior initial strength and long- term reliability, by dehydrating an optical fiber core coated with a resin composition and by forming a metallic or inorg. compound layer on the fiber core. CONSTITUTION:A base material for an optical fiber is drawn to form a glass fiber consisting of a core and a clad, and the surface of the fiber is coated with a resin composition before the fiber comes into contact with other solid matter. The fiber is dehydrated in vacuum, and while coiling the fiber as it is, a metallic or inorg. compound layer is formed. Thus, water contained in the resin composition layer and moisture in the air in the formation of the metallic or inorg. compound layer can be prevented from being absorbed in the metallic or inorg. compound layer, and the desired optical fiber is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a method for manufacturing an optical fiber having excellent initial strength and long-term reliability.

(B) Background Art Optical fins made of glass such as quartz glass tend to have minute defects on their surfaces during manufacturing or subsequent handling, and can easily break when exposed to an outer layer. Additionally, there are problems such as static fatigue, where moisture enters the defect and the defect grows under a constant load, leading to breakage.

In order to improve these drawbacks, methods such as (1) coating with a resin composition, Q) forming a layer of a mechanical compound or metal immediately after drawing the optical fiber and without mechanical contact are available. I'm at No. 9. However, although method (2) has the advantage of improving grain weight strength, static fatigue cannot be avoided due to the water permeability of the resin, and method (2) generally suppresses static fatigue, but often results in a deterioration of initial strength. , the drawback still remains.

As a combination of these two, a structure in which the first layer is a resin composition layer and the second layer is a metal has been considered, but simply coating with metal has little effect on suppressing static fatigue.

The reason is that water is pre-contained in the resin composition layer.

Moisture in the atmosphere at the time of metal coating is absorbed by the metal coating (&
This is because the amount is absorbed within the body.

(C) Disclosure of the Invention The present invention provides a method for manufacturing an optical fiber that has excellent initial strength and long-term reliability, and is intended to provide a method for manufacturing an optical fiber that has excellent initial strength and long-term reliability. After the optical fiber core wire coated with the resin composition is dehydrated in vacuum and before it is exposed to the atmosphere, a metal layer or an inorganic compound layer is formed on the resin composition coating layer. The present invention relates to a method of manufacturing an optical fiber.

To explain the method of the present invention in more detail, first, a fiber base material for optical transmission is drawn using a resistance furnace or the like to form a glass fiber consisting of a core and a cladding. coat the surface with a resin composition. As the resin composition used here, one or more types are selected from silicone resin, epoxy resin, 1/tan resin, nylon resin, polyethylene resin, etc. When forming multiple resin composition layers, , the first layer and the second layer may be covered.

Usually, the first layer of the resin composition is prepared by dipping, etc.
It is coated to a thickness of 150 μm and baked in an infrared oven, ultraviolet oven, etc. Thermoplastic resin is often used for the second layer resin composition, and is usually made by extrusion in the range of 01 to 0.
Finished with a thickness of 3mm.

The optical fiber coated with the resin composition is dehydrated in a vacuum chamber, and a layer of metal or inorganic compound is formed while winding it up. However, dehydration is possible if it takes a few mm1 (time), and dehydration is accelerated by heating to about 50 to 200°C.As metals, At, Cu, Ni
, Pb, Sn, 8b, In, At-Cu
, At-B1.

Pb-B1, Cu-8n, Pb-In %Pb
-8n, Sn-In, etc. are suitable, and the coating layer is formed by vacuum evaporation, ion blasting, sputtering, etc. In addition, as an inorganic compound, S soil 3N4. TiN, Tzu, TiO2, BN, A@03.5bo2.5nC
)2, etc. are used, and these are formed as a coating layer by CVD method or sputtering. The film thickness of the metal or inorganic compound layer is approximately Fi100A to 10μ.

It is preferable to perform the dehydration step and the metal or inorganic compound layer forming step in the same vacuum tank, but after dehydrating in advance, immediately transfer to another tank in which to form the metal or inorganic compound layer, and then remove the coating layer. It is also possible to form

B) Best Mode for Carrying Out the Invention Embodiment 1 An optical fiber core A having a main component of quartz glass 1 having a diameter of 125 μm and having a two-layer coating of silicone 2 and nylon 3 as shown in FIG. 17100℃ in X-2 tank 4 in the figure
At a constant temperature, it was left for one week under a vacuum of 10 mmI (6 is a vacuum pump), and then, while being wound up with a winder 6-6- in a vacuum chamber, At was transferred to At vapor deposition tank 7.7'. Approximately 1 μm of At was deposited. This is designated as B. Separately, as a comparative example, the above core wire was deposited with At of 11 tm without dehydration treatment.
The coated material is designated as C.

Example 2 The core wire used in Example 1 was heated to 1 mmT (
G for 3 days under a vacuum, then immediately transferred to the CvD device shown in Figure 8I\3, and wound the above core wire with a winder 1O-hIQ/ in a constant-vacuum chamber 8 (9 is a vacuum pump). At the same time, 1000X TiN coating was performed in a CVD reactor 11 connected to a Tiemperr 12° N2 cylinder 13. Let this be D.

FIG. 4 shows the optical fiber core A in FIG. 1 and At in Example 1.
The static fatigue characteristics of coated core wire B, Comparison ψ11 At-covered core wire C1 Example 20TIN' $ coated core wire Go) are shown. It is clear that the sound has been significantly improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a resin-coated optical fiber used in an example of the present invention, and FIGS. 2 and 3 are cross-sectional views of the resin-coated optical fiber coated with At and 'l'iN coatings on the core of FIG. 1. FIG. 4 is a diagram showing an outline of the method, and FIG. 4 is a graph showing the characteristics of the optical fiber obtained by the method of the present invention together with the characteristics of a comparative example. Agents 1) Akira’s agent Ryo Hagiwara −

Claims (1)

[Claims] An optical fiber <70 coated with a resin composition immediately after drawing and without mechanical contact with other solid materials is dehydrated in a vacuum and then coated with the resin composition before being exposed to the atmosphere. A method for manufacturing an optical fiber, comprising forming a metal layer or an inorganic compound layer on the layer.