JP2551068Y2 - Heat resistant optical fiber and heat resistant optical fiber with metal pipe - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber having excellent heat resistance.

[0002]

2. Description of the Related Art Optical fibers have been used not only for communication but also for data processing and measurement. Among these data processing and measurement fields, there is an increasing demand for heat-resistant optical fibers that can withstand high temperatures, particularly for measurement systems in high-temperature environments.

[0003] The current optical fiber cannot sufficiently meet this demand. That is, since the surface of the optical fiber made of quartz glass is easily damaged as in the case of ordinary glass, the resin is coated and protected at the same time as drawing. UV resin, silicone, and polyimide are usually used as the coating material to protect the optical fiber, but the temperature that can be used for a long time among such coating materials is only about 200 ° C. .

Therefore, an optical fiber coated with metal, ceramics or the like has been studied in order to be able to withstand a high temperature environment. However, optical fibers coated with metal tend to have microbend loss when a metal having excellent heat resistance is used, and have a poor heat resistance when a metal that prevents microbend loss is used.
For example, a metal coating of Al or the like can withstand high temperatures up to 500 ° C., but has a drawback in that the difference in thermal expansion coefficient is large and the surface of the optical fiber is damaged and the strength is deteriorated. On the other hand, ceramics are extremely weak against bending due to poor ductility, and were used as coatings for very thin films of several hundred to 1,000 mm like hermetic coatings.

[0005]

As described above, the above-mentioned prior art cannot manufacture an optical fiber having excellent heat resistance that can be used in a high-temperature environment.

[0006] Therefore, a coating material having excellent heat resistance was studied, and as a result, it was found that it was effective to use an organometallic polymer as the heat resistant coating material. However, according to the study of the present inventors, it has been found that an optical fiber coated with an organometallic polymer still cannot meet the requirements in the following points.

(1) Since fine particles such as ferrous (ZrO ₂ ) are added to the organometallic polymer in order to enhance heat resistance, the polymer is coated on the surface of the optical fiber when the polymer is coated on the optical fiber. Scratches will degrade the fiber strength.

(2) The optical fiber and the organometallic polymer have good adhesion, and when connecting at both ends of the optical fiber, a method of scraping the organometallic polymer is adopted. For this reason, the surface of the optical fiber is damaged when the polymer is removed, thereby deteriorating the fiber strength. It is almost impossible to remove the polymer without damaging the optical fiber.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an optical fiber having high strength, excellent heat resistance and easy connection.

[0010]

In order to achieve the above-mentioned object, the present invention provides a heat-resistant optical fiber in which an optical fiber is coated with carbon, an organic polymer and an organometallic polymer in this order.
I'm Aiba. The optical fiber may be inserted into a metal pipe and the pipe may be filled with an inert gas . In the present invention , as the organic polymer, an ultraviolet curable resin is preferred.
Ku, Examples of the organometallic polymer, preferably a good polytitanocarbosilane heat resistance.

[0011]

[Function] By coating an organic metal polymer on an optical fiber through an organic polymer, the optical fiber can be protected from fine particles in the coating of the organic metal polymer even when the organic metal polymer is coated, and the surface of the optical fiber can be protected. Thus, an optical fiber having high initial strength and excellent heat resistance can be obtained. In addition, since the organic polymer is interposed between the optical fiber and the organic metal polymer, the organic metal polymer can be easily removed without damaging the optical fiber, and the connection work at the terminal is much easier. Becomes

Further, by interposing carbon between the organic polymer and the optical fiber, even if the organic polymer is carbonized and generates hydrogen in a high-temperature environment, the hydrogen is introduced into the optical fiber. Spreading can be prevented, and an increase in transmission loss due to the spreading can be prevented.

Further, by inserting the heat-resistant optical fiber thus coated into a metal pipe and filling the pipe with an inert gas, the inside of the pipe becomes anoxic, and even at high temperatures, the organic metal Since thermal oxidative decomposition of the polymer is eliminated, it is possible to prevent an increase in transmission loss and a deterioration in strength caused by this.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of a heat-resistant optical fiber containing a metal pipe according to the present invention. In the figure, 1 is an optical fiber wire made of quartz glass, 2 is a carbon layer formed on the outer periphery of the optical fiber wire 1, 3 is an organic polymer layer formed on the carbon layer 2 and 4 is an organic polymer layer. These are organometallic polymer layers coated on the polymer layer 3, and these constitute the heat-resistant optical fiber 5 having a three-layer coating structure. Reference numeral 6 denotes a metal pipe whose both ends are sealed with an epoxy resin or the like, into which a heat-resistant optical fiber 5 is inserted and an inert gas 7 is filled. Heat-resistant optical fiber with pipe 8
Is configured. Here, as the material of the metal pipe 6, SUS, aluminum, copper, iron, titanium or the like is used, and as the inert gas 7, nitrogen (N ₂ ),
Helium (He), argon (Ar), or a mixed gas thereof is used. Also, both ends of the optical fiber 5
It is exposed from the end of the pipe 6 for connection.

Next, a heat-resistant optical fiber 8 containing a metal pipe 8
A description will now be given of a specific example and evaluation of its characteristics.

First, on the outer periphery of the single-mode optical fiber 1 of the 1.3 μm band, carbon was applied so as to have a thickness of 800 °, an ultraviolet curable resin (organic polymer) was applied so as to have a thickness of 10 μm, and Was coated in order with a polytitanocarbosilane (organometallic polymer) so that the thickness was 15 μm, thereby producing a heat-resistant optical fiber 5. Next, this optical fiber 5 is placed in a SUS pipe 6 having an outer diameter of 1.8 mm and an inner diameter of 1.4 mm in a SUS pipe 6.
0.2%, after replacing the inside of pipe 6 with N ₂ gas,
Both ends of the pipe 6 were sealed with an epoxy resin, and a heat-resistant optical fiber 8 containing a metal pipe 500 m was prototyped.

Then, 100 m of the center portion of the heat-resistant optical fiber 8 containing the metal pipe thus produced was put into a high-temperature furnace,
The properties were evaluated by treating at a high temperature of ° C. As a result, 5
After treatment at 00 ° C for 1 hour, the loss for a wavelength of 1.3 μm is about
Although it increased by 0.2 dB, there was no change thereafter. From this result, it can be seen that the increase in loss due to the oxidative deterioration of polytitanocarbosilane did not occur. The increase in the loss at the beginning of the treatment is due to the microbend or the like occurring in the optical fiber 5 at 500 ° C. due to the expansion of the pipe 6 or the carbonization of the ultraviolet curable resin. H ₂ (hydrogen) is generated by carbonization of the ultraviolet curable resin.
_It can be seen that the diffusion of _{2 into} the optical fiber 1 is blocked by the carbon layer 2.

Further, as a result of evaluating the tensile properties of the heat-resistant optical fiber 5, the tensile strength of the optical fiber 5 was 6 k on average.
gf. Conventionally, since the fine particles of SiO ₂ or ZrO ₂ are added to the polytitanocarbosilane in order to enhance the heat resistance, the optical fiber 1 is damaged when the polytitanocarbosilane is coated. And the tensile strength was 2-3 kgf. In the above specific example, the surface of the optical fiber 1 is protected by the ultraviolet curing resin interposed between the polytitanocarbosilane and the optical fiber 1 so that the fiber strength is increased without being damaged. I understand.

When the coating is removed at the end of the optical fiber 5, the polytitanocarbosilane can be easily scraped off without damaging the optical fiber 1;
After the removal, the connection became possible in the same process as the conventional plastic-coated optical fiber. In other words, by interposing an ultraviolet curable resin between the polytitanocarbosilane and the optical fiber 1, the connection work becomes much easier as compared with a conventional optical fiber only coated with polytitanocarbosilane. Was. In addition, the fiber strength was maintained without reducing the strength of the optical fiber 1 when removing the polytitanocarbosilane.

Accordingly, a carbon layer 2, an organic polymer layer 3, and an organometallic polymer layer 4 are formed in this order on the outer periphery of the optical fiber 1 and are placed in a metal pipe 6 filled with an inert gas 7. By inserting, a heat resistant optical fiber 8 containing a metal pipe can be obtained which has high strength and excellent heat resistance even in a high temperature environment and can perform the same connection work as a conventional plastic coated optical fiber.

Further, by forming the organic polymer layer 3 from a resin containing no metal, the strength of the fiber can be further increased without lowering the fiber strength due to the metal. When a metal is contained in the organic polymer layer 3, for example, a silicone resin is thermally decomposed at a high temperature to form Si.
When O ₂ remained and bending was applied to the optical fiber, the fiber strength was deteriorated. However, such a problem did not occur when an ultraviolet curable resin containing no metal was used.

[0023]

[Effect of the Invention] In summary, according to the present invention, since the optical fiber is coated with carbon, an organic polymer and an organic metal polymer in this order, a heat-resistant optical fiber having high strength, excellent heat resistance, and easy connection is provided. Obtainable.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a heat-resistant optical fiber containing a metal pipe of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber wire 2 Carbon layer 3 Organic polymer layer 4 Organometallic polymer layer 5 Heat resistant optical fiber 6 Metal pipe 7 Inert gas 8 Optical fiber containing metal pipe

Continuing on the front page (72) Inventor Go Okubo 5-1-1, Hidaka-cho, Hitachi City, Ibaraki Prefecture Inside the Electric Wire Research Laboratory, Hitachi Cable Co., Ltd. No. 1 Inside the Hidaka Plant of Hitachi Cable Co., Ltd. JP-A-64-13507 (JP, A) JP-A-63-189814 (JP, A)

Claims (4)

(57) [Scope of request for utility model registration] 1. An optical fiber comprising a carbon fiber and an organic metal
In a heat-resistant optical fiber that is sequentially coated with limers,
The organic material between the carbon and the organometallic polymer
To protect optical fiber from fine particles in metal polymer
Heat resistant light characterized by intervening organic polymer
fiber. 2. The heat-resistant optical fiber according to claim 1, which is made of a metal.
Insert it into the pipe and fill it with inert gas
A heat-resistant optical fiber containing a metal pipe. 3. The heat-resistant optical fiber containing a metal pipe according to claim 2, wherein said organometallic polymer is polytitanocarbosilane. 4. The heat-resistant optical fiber containing a metal pipe according to claim 2, wherein the organic polymer is an ultraviolet curable resin.