JPH013031A - Infrared fiber manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing an infrared fiber suitable for transmitting infrared light, particularly light of 2 to 14 μm.

[Prior art and its problems] Infrared fibers can be manufactured by heating and softening chalcogenide glass in a crucible and spinning it. However, in the conventional spinning method, chalcogenide glass contained in a crucible is The whole was heated to around the softening point temperature (hereinafter referred to as Ts).

However, chalcogenide glass is thermally unstable and tends to crystallize if kept at a temperature near Ts for a long time.

For this reason, in the conventional method described above, crystal grains are generated and grown in the glass in the crucible over time, and these crystal grains remain in the fiber after spinning, resulting in an increase in the transmission loss of the fiber. However, there were problems such as fiber breakage.

In addition, in the conventional method, the entire spinning apparatus including the crucible is placed in an inert gas atmosphere to prevent oxygen impurities that cause transmission loss from getting into the softened glass and the fiber spun from it. There is.

Although this is effective in preventing oxidation, since the temperature of the inert gas also rises to around Ts in this method, crystal grains are generated in the spun fiber for the same reason as mentioned above. The problem was that it was easy. In addition, as shown in Figures 3 and 4, chalcogenide glass (raw material)
If the gap between crucible 1 and crucible 2 is small and the glass is heated unevenly, the glass in that area will stick to the inner wall of crucible 2 (
1 prevents the glass from descending, and the glass facing the attached part 9 is actively spun along the sides, so a hole 10 is created in the glass part to be melt-spun, and the applied pressure is released from the hole, causing the spinning process. It may not be possible to do so.

An object of the present invention is to provide a new method for spinning chalcogenide glass, which can suppress the generation and growth of crystal grains caused by heating, and can therefore produce an infrared fiber with low transmission loss. Furthermore, it is an object of the present invention to provide a spinning method that can prevent applied pressure from escaping along the sides of chalcogenide glass, improve yield, and perform stable spinning over a long period of time.

[Means for Solving the Problems] The method of the present invention is a method for manufacturing an infrared fiber by heating and softening chalcogenide glass in a crucible and extruding it from a spinning hole at the tip of the crucible. It is characterized by heating only the vicinity of the hole locally and drawing out the glass as a fiber while maintaining the viscosity of the glass in the range of 105 to 107 voids.

In this case, it is important to provide a gap between the chalcogenide glass and the crucible. Without this gap, the locally heated glass would not be smoothly supplied to the mouth at the bottom of the crucible.
Spinning becomes impossible. Also, this gap is 2% of the crucible inner diameter.
If the glass is heated unevenly, the acid will deposit on the glass crucible in that area and prevent the glass from descending, increasing the gap between the glass on the opposite side of the fused part and the crucible. It spreads to the spinneret at the bottom of the crucible, and the applied gas escapes. Therefore, it is desirable that the gap between the crucible inner wall and the outer diameter of the glass raw material be 2% or more of the crucible inner diameter. The fiber drawn out from the spinning hole is immediately passed through a cooling zone in which an inert gas flows to be rapidly cooled.

[Function] According to the present invention, the glass in the crucible is locally heated near the spinning hole so that the viscosity becomes 105 to 107 voids, and the glass is straightly spun. Therefore, the glass will not crystallize due to being heated in the crucible for a long time. The localized heating of the present invention is achieved by installing a heating furnace with a narrow heating width near the spinning hole of the crucible. Here, the heating width refers to the length (distance 11) measured in the drawing direction of the glass. If the heating width is too wide, the glass tends to crystallize, so the width is generally preferably about 15II11 or less.

The fiber drawn from the spinning hole is guided into a cooling zone where an inert gas flows. The cooling zone is constructed by connecting a space separated by a suitable partition wall to the heating furnace, and flowing an inert gas into the space.

Since the fiber immediately after spinning is rapidly cooled in this cooling zone without contacting with oxygen, it is neither oxidized nor crystallized.

[Example] 1 The composition of the glass to be rubbed is Ge: 28.5 mol%, SC
:26', 5 mol%, Te: 45 mol%, among each raw material with a purity of 6N or more, Ge is 900%.
℃ for 2 hours, and Se and Te were purified by distillation in an argon atmosphere at 450℃ and 750℃, respectively, and then placed in a dehydrated quartz container and heated to 10 Torr or less. 1 while holding
Heated at 70°C for 12 hours. Thereafter, the vacuum degassing port of the quartz container was sealed off with a gas burner, and the container was shaped into an ampoule shape. One person placed the obtained quartz ampoule in an indigo electric furnace and heated it for 8 hours.
After melting at 50° C. for 24 hours and at 600° C. for 2 hours, GeSe glass was obtained by taking it out into the atmosphere and rapidly cooling it. Next, an infrared fiber was manufactured from this glass using the apparatus shown in FIG.

The glass 1 is placed in a crucible 2, and the tip of the crucible where the spinning hole is located is equipped with an opening corresponding to the spinning hole, and the tip of the crucible is 8 m long.
It was fitted into the heating furnace 3 having a heating width of m without any gaps.

Next, local heating was performed in a heating furnace near the spinning hole of the crucible 2 to bring RiuA to 288° C., at which the viscosity of the glass became 10 6 poise. Then, using Ar gas from the top of the crucible,
(ff/cnf pressure was applied, and the fiber 5 was drawn out from a spinning hole with an outer diameter of 3.0 mm provided at the tip of the crucible.The drawn fiber 5 was immediately transferred to a cooling zone connected below the heating furnace 3. Guided by Vi4, 500c in this band
It was quenched by Ar gas flowing at a flow rate of c/min. The ^r gas temperature at this time was 25°C.

The spinning speed is about 50 cm per minute, allowing stable spinning.
17 fibers each having a length of 500 μm and approximately 257 nm. The minimum loss of this fiber is 1.0 dB/1 at a wavelength of 9.0 μm.
It was a low 10 loss. 13. When putting glass 1 into crucible 2 using the same equipment and conditions, if gaps 8 of 2%, 2.5%, and 3% of the inner diameter of the crucible are provided as shown in FIG. It was no longer combed uniformly or fused to the crucible, and the glass applied to the top no longer leaked out of the spinneret.

When the same glass was spun using the conventional method, crystal grains were generated and grew in the glass, and the fibers often broke during spinning, and the broken fibers did not transmit any light at all.

[Effects of the Invention] The method of the present invention locally heats only the glass near the spinning hole to maintain the viscosity within the range of 105 to 107 poise, and immediately after spinning, the glass is heated with an inert gas. Since the fiber is rapidly cooled, the generation or growth of crystal grains in the glass or fiber can be suppressed to a low level.
Therefore, long infrared fibers with low 10 loss can be stably manufactured.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the apparatus used to carry out the manufacturing method of the present invention, Fig. 2 is a cross-sectional view of the apparatus showing another method of implementation, and Fig. 3 is a small FIG. 4 is a sectional view taken along the line IV--IV in FIG. 1... Chalcogenide glass, 2... Crucible, 3...
... Heating furnace, 4... Cooling zone, 5... Infrared fiber, 6... Inert gas inlet, 7... Inert gas outlet,
8... Gap.

Claims (1)

[Claims] 1. In a method for producing an infrared fiber by spinning chalcogenide glass heated and softened in a crucible, the viscosity of the glass is reduced to 1 by locally heating and softening only the vicinity of the spinning hole of the crucible.
A method for producing an infrared fiber, which comprises spinning while maintaining the poise within a range of 0^5 to 10^7. 2. The method for producing an infrared fiber according to claim 1, characterized in that the fiber immediately after spinning is passed through a cooling zone separated by partition walls. 3. The method for manufacturing an infrared fiber according to claim 2, which comprises flowing an inert gas into the cooling zone. 4. The method for manufacturing an infrared fiber according to claim 1, characterized in that a gap is provided between the chalcogenite glass and the crucible. 5. The method for manufacturing an infrared fiber according to claim 4, wherein the gap is 2% or more of the crucible inner diameter.