JPS6299711A - Covered optical fiber core - Google Patents

Abstract

PURPOSE:To improve low temperature characteristic by providing an intermediate buffer layer made of mold release agent at the interface between optical fiber element wire made by applying an inner layer covering layer having small coefficient of thermal expansion and an intermediate layer covering layer on bare optical fiber and an outermost layer covering layer having large coefficient of thermal expansion. CONSTITUTION:In a covered optical fiber consisting of an inner layer covering layer made of ultraviolet curing resin having Young's modulus of 0.1-2.0kg/mm<2> at normal temperature applied on a bare optical fiber to the thickness of 0.03-0.10mm, an intermediate layer covering layer made of ultraviolet curing resin having Young's modulus of 20-80kg/mm<2> at normal temperature applied on the outer periphrry of the inner layer covering layer to the thickness of 0.02-0.10mm, and an outermost layer covering layer made of nylon having Young's modulus of 20-150kg/mm at normal temperature applied on the outer periphery of the intermediate layer covering layer to the thickness of 0.10-0.30mm, an intermediate buffer layer of 0.02-0.10mm thick made of mold release agent is provided at the interface between the intermediate layer covering layer and outermost layer covering layer. Thereby, the bare optical fiber is not affected by contraction distortion of nylon, a direct outer layer covering layer and microbending due to buckling is hard to occur.

Description

[Detailed Description of the Invention] [Summary of the Invention] The outer periphery of a bare optical fiber has a Young's modulus of 0.1-2 at room temperature.
．． Thickness 0.0 with beak external line hardening resin of 0 Kg/mm”
An inner coating layer with a thickness of 3 to 0.10 mm, an intermediate coating layer with a thickness of 0.02 to 0.10 mm made of ultraviolet curable resin with a Young's modulus of 20 to 80 Kq/mm at room temperature, and a Young's modulus of 20 to 150 Kg/mm at room temperature. Thickness according to Naio7 of 1.10 to 0.30 yam [thickness of 0.02 to 0.02 to 0.02 to 0.30 yam due to a release agent at the interface between the intermediate coating layer and the outermost coating layer of a coated optical fiber coated with an outermost coating layer of 1.10 to 0.30 yam A coated optical fiber that maintains low-temperature properties that prevent optical transmission loss from increasing at low temperatures by providing a 0.10 mm intermediate buffer layer.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a coated optical fiber having excellent low-temperature characteristics of optical transmission loss.

[Conventional technology]

Although a large number of reports have already been made on the coating structure of coated optical fibers, there is still no coated optical fiber that fully satisfies the so-called low-temperature characteristics, which means that optical transmission loss does not increase easily at low temperatures. Not discovered.

Conventionally, in order to prevent deterioration of transmission characteristics due to the microbending phenomenon, the inner coating layer was made of ultraviolet curing resin with a low Young's modulus (hereinafter referred to as UV 44 resin), and the intermediate coating layer was made of ultraviolet curing resin with a relatively high Young's modulus. The structure of the coated optical fiber is made of UV4# resin and the outermost coating layer is made of nylon with a high Young's modulus, and generally has a low Young's modulus of 0.1 to 2.0 Ky/ram" at room temperature. The inner coating layer is formed with a thickness of 0.03 to 0.10 mm according to the Young's modulus of UV Snow'1, and the Young's modulus is 20 to 20 at room temperature.
The intermediate coating layer is made of UV light resin with a relatively high Young's modulus of 80 Kg/mm" and has a thickness of 0.602 to 0.10 w1L, and the Young's modulus at room temperature is 20 to 1 s oxc.
t/mm" is used.

FIG. 4 shows a cross-sectional structure of a conventional coated optical fiber.

1 is a bare optical fiber, 2 is an inner coating layer made of a low 7'f modulus LDUV resin, 6 is an intermediate coating layer made of a relatively high Young's modulus (LV resin), and 5 is an outermost coating layer made of nylon with a high Young's modulus. It is.

[Problem that the invention seeks to solve]

Conventional coated optical fibers of this type have the drawback of not fully satisfying low-temperature characteristics. This is because the coefficient of thermal expansion of the outermost coating layer, nylon, is about three orders of magnitude larger than that of the bare optical fiber, so the nylon contracts at low temperatures, causing the bare optical fiber to buckle and cause microbending. It is believed that the main reason for not satisfying the low-temperature characteristics is the increase in optical transmission loss.

[Means for solving problems]

In order to solve the conventional problems, the present invention provides a bare optical fiber with a Young's modulus of 0.1 to 2.0 Kg/m- at room temperature.
The inner coating layer was applied to a thickness of 0.05 to 0.10 mm using UV'@fFl of The intermediate coating layer is applied with a thickness of = 0.10 mm, and the Young's modulus at room temperature is 2 on the outer periphery of the intermediate coating layer.
0.10 to 0 by nylon of 0 to 150Kg/mm
．． In a coated optical fiber consisting of an outermost coating layer applied to a thickness of 30 mm, an intermediate buffer with a thickness of 0.02 to 0.10 mm made of a release agent is applied at the interface between the intermediate coating layer and the outermost coating layer. It is characterized by having layers.

[For production]

The coated optical fiber according to the present invention has an intermediate layer formed by applying a release agent to the interface between the optical fiber coated with an inner coating layer and an intermediate coating layer having a small coefficient of thermal expansion, and the outermost coating layer having a large coefficient of thermal expansion. By providing the buffer layer, in the coated optical fiber core of the present invention, the bare optical fiber is not directly subjected to shrinkage strain of the nylon outer coating layer even at low temperatures, and microbending due to buckling is less likely to occur. . Therefore, not only are the low-temperature properties, which were not fully satisfied with conventional coated optical fibers, significantly improved, but also the lateral pressure resistance is improved by increasing the thickness of the outermost coating layer with a high Young's modulus. There is no deterioration in low temperature characteristics. Examples will be described below based on the drawings.

〔Example〕

FIG. 1 shows a cross-sectional structure of a coated optical fiber according to the present invention. 1 is a single mode bare optical fiber with an outer diameter of 125 μm, and 2 is a Young's modulus of 0.17 Kg/1wn at room temperature.
``Inner coating layer formed with a thickness of 72.5 μm by UTl coating, 3 has a Young's modulus of 50 Kg/mm at room temperature.''
4 is the intermediate buffer layer formed with a thickness of 15 INn using silicone oil as a template agent, 5 is the Young's modulus at room temperature '+ 00 Kg/ The outermost coating layer was formed of nylon with a thickness of 250 μm, and the outer diameter of the coated optical fiber was 930 μmφ.In this example, silicone oil may be used as a mold release agent. .

FIG. 2 shows an outline of the manufacturing process for the coated optical fiber of this example. Immediately after drawing from the optical fiber base material, the inner coating layer and the intermediate coating layer made of UV resin are each treated with UV light.
U coated with a resin coating device and wound up with a winding machine
V resin coated optical fiber wire supply 6
Immediately after applying an intermediate buffer layer of silicone oil supplied from a silicone oil supply device 10 using a dipping die 7, an outermost coating layer of nylon is applied using a nylon coating device 8, and the material is wound up using a winder 9.

In addition, in order to compare with the coated optical fiber core wire of this example, the cross-sectional structure of FIG. A coated optical fiber core exhibiting the following properties was also manufactured. The structure of this conventional coated optical fiber is a single-mode bare optical fiber with an outer diameter of 125 μmφ and a Young's modulus of 0.1 at room temperature.
Inner coating layer formed with a thickness of 72.5μ from UV resin of 7Kg/m-, Young's modulus of 50Kg at room temperature.
Intermediate coating layer formed with a thickness of 65 μm from a UV resin of 100 μm/mm”, Young's modulus at room temperature of 1QQgg/mm”
The outermost coating layer is made of nylon with a thickness of 250μ, and the outer diameter of this coated optical fiber is 900μ.
It was μm.

FIG. 5 shows the test results of the temperature characteristics of optical transmission loss at a wavelength λ=1.3 μ of the above-mentioned coated optical fiber according to the present invention and the conventional coated optical fiber. ■ indicates the present invention, and ■ indicates the conventional type. The measurements were carried out using coated optical fibers of the present invention and conventional type, each measuring 20GQm, Q, and 4mφ.
This was done by making the material into a bundle and eliminating the effects of bobbin winding. As a result, the coated optical fiber according to the present invention shows no increase in optical loss up to -60°C, and exhibits better low-temperature characteristics than the conventional coated optical fiber. The fiber parameters of the coated optical fiber according to this example are LP at a wavelength of 1.5 μm, mode outer diameter of 9.7
The cutoff frequency wavelength of the mode was 1.17 μm, and the cladding diameter was 125 μmφ.

〔Effect of the invention〕

As described above, the coated optical fiber of the present invention comprises an optical fiber in which a bare optical fiber is coated with an inner coating layer and an intermediate coating layer each having a small coefficient of thermal expansion, and an outermost coating layer having a large coefficient of thermal expansion. By providing a structure in which an intermediate buffer layer made of a release agent is provided at the interface with the layer, the low-temperature characteristics, which were not fully satisfied with conventional coated optical fibers, have been significantly improved. Furthermore, in order to improve the lateral pressure resistance, even if the thickness of the outermost coating layer is increased or the Young's modulus of the nylon used for the outermost coating layer is set high, the low temperature characteristics do not deteriorate.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional structure of a coated optical fiber according to the present invention.
Fig. 2 is an overview of the manufacturing process of the coated optical fiber according to the present invention, Fig. 3 is the temperature characteristic test result of optical transmission loss of the coated optical fiber of the present invention and the conventional coated optical fiber, and Fig. 4 is the result of the conventional coated optical fiber. This is the cross-sectional structure of the core wire. DESCRIPTION OF SYMBOLS 1... Bare optical fiber, 2... Inner layer coating layer, 3... Intermediate layer coating layer, 4... Intermediate buffer layer, 5... Outermost layer coating layer, 6... Optical fiber wire supply , 17... Dipping die, 8... Nylon coating device, 9... Winding machine,

Claims (1)

[Claims] The bare optical fiber has a Young's modulus of 0.1 to 2.
0.03~0 due to 0Kg/mm^2 ultraviolet curing resin
．． The inner coating layer is applied to a thickness of 10 mm, and the Young's modulus at room temperature is 20 to 80 Kg/mm^ on the outer periphery of the inner coating layer.
The intermediate layer coating layer is applied with a thickness of 0.02 to 0.10 mm using the ultraviolet curable resin of No. 2, and the outer periphery of the intermediate layer coating layer has a Young's modulus of 20 to 150 K at room temperature.
0.10-0.30mm by g/mm^2 nylon
In a coated optical fiber coated wire consisting of an outermost coating layer applied to a thickness of A coated optical fiber core characterized in that it is formed by providing layers.