JPH0342643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber that can improve the phenomenon of increased transmission loss due to aging.

Background and Purpose It has recently been found that transmission loss increases with time in optical fiber cables.
The reasons for this are currently thought to be as follows.

1) Hydrogen gas is generated by hydrolysis or thermal oxidation of plastic, which is the constituent material of the optical fiber, and this hydrogen gas diffuses into the optical fiber, causing an increase in loss.

2) A part of the diffused hydrogen gas combines with ■■■ Tortoise Shell [0001] ■■■ to become ■■■ Tortoise Shell [0002] ■■■, and some of it is retained as hydrogen molecules in the network structure of the glass. be done.

3) Hydrogen gas can be generated not only from the above-mentioned plastics, but also when water enters an optical fiber cable made of different metals, forming a battery and generating hydrogen gas.

4) Even when the same amount of hydrogen gas is generated, the loss increase characteristics differ depending on the composition and composition ratio of the optical fiber. In other words, the increase in OH groups will not bond with hydrogen unless defective oxygen with dangling bonds is already present in the glass.

5) The number and type of defects strongly depend not only on the composition and composition ratio of the optical fiber, but also on the manufacturing method and conditions.

In consideration of the above points, this invention has been developed so that hydrogen gas generated from the coating material etc. is absorbed on the way.
The purpose of this invention is to provide an optical fiber having a structure that does not reach the core.

Structure of the invention (see Figure 1) The optical fiber has a glass portion 10 in the center.
It has a structure in which a resin coating is provided over the core (including the core 11 and the cladding 12), and the resin of the coating contains a substance that easily absorbs hydrogen gas. shall be.

More detailed explanation of the structure Palladium is well known as a material that efficiently absorbs hydrogen gas. The storage capacity of metallic palladium is usually 300 to 1000 times its volume.

Platinum is another known substance that easily absorbs hydrogen gas. In addition, nickel, titanium,
Iron also has this property. However, palladium can be said to be the material with the greatest occlusion effect.

Further, the substance that easily absorbs hydrogen gas may be inserted into either the primary coating 14 or the secondary coating 18. But it's even better if you include both of them.

However, if a substance 28 that easily absorbs hydrogen gas is added to the portion of the modified silicone resin layer 15 that is in contact with the glass portion 10, it is effective in reducing the increase in loss, but it is easy to absorb hydrogen gas. In practice, this is not possible because the substance 28 would damage the glass part 10 and deteriorate its mechanical properties.

Example 1 The base material 20 produced by the VAD method was made into a fiber using the spinning apparatus shown in "Fig. 2". That is, the glass fiber 10 immediately after spinning is passed through the coater 22 and the crosslinking tower 24 to coat the modified silicone resin layer 1.
A silicone buffer layer 1 containing a substance 28 that easily absorbs hydrogen gas is formed by forming a silicone buffer layer 1 containing a substance 28 that easily absorbs hydrogen gas.
6 was formed.

Thereafter, a secondary coating 18 of nylon was applied to form an optical fiber having a cross section as shown in FIG.

Its dimensions (outer diameter of each part) are as follows: glass part 10
is 125 μm, modified silicone resin layer 15 is 250 μm,
Silicone buffer layer 16 is 400μm, secondary coating 18 is
It is 0.9mm.

The transmission loss increase characteristics were determined by an accelerated test method.

That is, the produced optical fiber core wire was kept in an oven at 200° C. for 2 hours, and the loss wavelength characteristics before and after the oven were measured using a monochromator.

The value of increase in loss was determined from the increase value at a wavelength of 1.39 μm, where the increase in loss due to OH groups is significant.

Table 1 shows the values of increase in loss when the parts by weight of palladium were varied.

■■■ Turtle Shell [0001] ■■■ From this, it can be seen that 0.1 part by weight of palladium is sufficiently effective.

Example 2 Metallic palladium was applied to a nylon secondary coating 18.

Table 2 shows the increase in loss when the parts by weight of palladium were varied.

■■■ Turtle Shell [0002] ■■■ From this, it can be seen that the effect is similar to that when palladium is added to the silicone buffer layer 16.

Effects of the invention (1) Since a substance that easily absorbs hydrogen gas is blended into the coating resin, hydrogen gas generated within the coating resin is absorbed within the resin, and almost no hydrogen gas reaches the core. .

(2) Hydrogen gas originating from not only the resin in the coating but also the metal in the optical fiber cable is absorbed within the coating and does not reach the core.

(3) The target is not optical fibers for special purposes, but the most common optical fibers with resin coatings used for optical communications. Since the amount may be very small, it does not impair the characteristics of the resin coating to fulfill its original role.

[Brief explanation of drawings]

The drawings relate to an embodiment of the present invention, and FIG. 1 is a cross-sectional explanatory diagram, and FIG. 2 is a schematic explanatory diagram of a spinning device. 10: Glass portion (including core 11 and cladding 12), 14: Primary coating, 15: Modified silicone resin layer, 16: Silicone buffer layer, 18: Secondary coating, 28: Substance that easily absorbs hydrogen gas.

Claims (1)

[Claims] 1. An optical fiber having a glass portion including a core and a cladding in the center, and a resin coating provided thereon, wherein hydrogen gas is easily absorbed in the resin of the coating. An optical fiber characterized by a combination of substances. 2. The optical fiber according to claim 1, characterized in that a substance that easily absorbs hydrogen gas is blended into the coating resin at a portion other than the portion in contact with the glass.