JPS5869738A - Radiation-resistant optical fiber - Google Patents

Abstract

PURPOSE:The titled optical fiber having improved radiation resistance and transmission characteristics, by forming a clad on the outer periphery of a quartz core containing a dopant consisting of Ce. CONSTITUTION:A mixed powder 4 of fine powdery SiO2 in the form of soot obtained by the thermal decomposition and flame hydrolysis of SiCl4 and CeCl4 in the vapor phase and fine powdery CeO2 as a dopant is packed in a quartz glass tube 5. The quartz glass tube 5 is then held by a holding tool 6 capable of freely rising and lowering and rotating, and inserted in a heating furnace 7 to vitrify the mixed powder 4, which is integrated with the quartz glass tube 5 to give a base material for an optical fiber. The resultant base material is then spun by the conventional method to afford an optical fiber 1 consisting of a core 2 containing Ce as a dopant and a clad 3 around the clad 2. Thus, the optical fiber 1, having no increase in loss to make the transmission impossible even by the application of radiation, and suitable for constituting a communication system around atomic energy facilities, etc. is obtained.

Description

[Detailed description of the invention] The present invention relates to radiation-resistant optical fibers.

In a communication system that uses optical fiber, if it is installed near a nuclear reactor or fusion reactor, the loss of the optical fiber increases due to radiation, and the increase in loss is so large that the communication system becomes meaningless. It has become a thing.

This has been studied, and it has been reported that optical fibers made of cerium-containing silicate glass (multicomponent glass) have a relatively small increase in loss due to radiation irradiation.

However, in the case of the above-mentioned silicate glass optical fiber, the loss is large even when it is not irradiated as a problem before being irradiated with radiation, and therefore its practicality for communications is quite poor.

In view of the above-mentioned circumstances, the present invention aims to provide a new optical fiber that satisfies both radiation resistance characteristics and transmission characteristics, and its configuration will be explained below with reference to illustrated embodiments.

In Fig. 1, (l) is a Si type optical fiber.
+21 is the core, and (3) is the cladding around the core.

In the above optical fiber (1), the core (2) is quartz-based (Si02) containing cerium (Ce02), the cladding (3) is quartz-based, and the core (2) contains cerium as a dopant. As a result, the refractive index is higher than that of the cladding (3).

Since the core (2) of the optical fiber (1) with such a configuration contains cerium, the transmission characteristics hardly change even under radiation exposure.
Since it has i02 as its main component, it has high transmission characteristics, and therefore, in the case of this optical fiber t11, it can be said that it has low loss and good radiation resistance when exposed to radiation.

The composition constituting the core (2) is the above-mentioned 5102 and CeO2, as well as GeO2 and P205.8 b20 within a range that does not impair radiation resistance properties.
A dopant such as s may be included in the 8i02 CeO□ system.

A manufacturing example of the optical fiber of the present invention will be briefly explained in the second drawing.
A mixed powder formed by mixing two fine powders, (5) is the mixed powder (
4) is housed in a filled state, and the 5i02 fine powder and CeO2 fine powder in the mixed powder (4) are as follows:
Thermal decomposition reaction of 8iCt4 and CeC1+ in the gas phase,
It is a soot-like molten product produced by flame hydrolysis reaction.

The quartz glass tube (5) filled with the mixed powder (4) as described above is held by a vertically movable and rotatable clamping tool (6) shown in Fig. 2, and then placed in a heating furnace such as an electric furnace. (7) and undergoes heat treatment, and the heat treatment at this time turns the mixed powder (4) into transparent vitrification.
It is integrated with a quartz glass tube (5).

That is, the base material for the optical fiber is produced as described above, the mixed powder (4) becomes the glass layer for the core, and the quartz glass tube (5) becomes the glass layer for the cladding.

Thereafter, the optical fiber base material thus produced is spun according to a conventional method to form the above-mentioned optical fiber (IJ).

In addition, when obtaining the above optical fiber (1), its base material is V
It may also be produced by the AD method, in which case a solution containing cerium ions is exposed with an ultrasonic nebulizer,
This can be introduced into a flame for forming a core layer and doped.10 As explained above, in the present invention, in an optical fiber comprising a core and a cladding around the outer periphery, the core contains a dopant. It is characterized in that it is made of quartz-based material, and that part or all of its doping agent is made of cerium.

Therefore, by having a core made of quartz, not only can high transmission characteristics be ensured, but since the core contains cerium as a dopant, there is no increase in loss that would cause communication failure even when exposed to radiation. As a result, an optical fiber suitable for constructing a communication system in the vicinity of nuclear facilities, etc. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the optical fiber of the present invention, and FIG. 2 is a schematic illustration showing an example of manufacturing the same optical fiber. (1)...Optical fiber (2)...Core (3)...Clad Fig. 1 Fig. 21ya

Claims (1)

[Claims] A radiation-resistant optical fiber comprising a core and a cladding around the core, wherein the core is made of quartz-based material containing a dopant, and the dopant is partially or entirely made of cerium.