JPS63241504A - Production of single crystal fiber - Google Patents

Abstract

PURPOSE:To obviate fluctuation in the outside diameter of a single crystal fiber and to improve the quality thereof by preparing a columnar base crystal rod, melting the end of the base crystal rod while etching the outer circumference thereof to control the outside diameter of the rod and pulling up the single crystal fiber continuously. CONSTITUTION:A seed crystal is brought into contact with the melt of a starting raw material and is grown to prepare the base crystal rod 1. The outside diameter of the resultant base crystal rod 1 is continuously controlled by etching the outer circumference thereof. The rod 1 controlled in the outside diameter is delivered upward by delivery belts 5, 5 and the top end of the rod 1 is heated and melted by a heating means 6. The seed crystal of a prescribed size is brought into contact with the molten part and is continuously pulled upward by pulling up belts 7, 7. The single crystal fiber 8 having the stable outside diameter and the high quality is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for producing a single crystal fiber used as, for example, a laser cord, a high-performance optical device such as an optical isolator, a super heat-resistant fiber, or the like.

"Prior Art and its Problems" Conventionally, such single crystal fibers have been manufactured by various methods.

For example, the floating zone melting method (hereinafter referred to as FZ method) uses LiN bOs, LiTa
A method in which a single crystal fiber is obtained by partially heating and melting the end of a cylindrical mother crystal made of an oxide such as O5, bringing a seed crystal into contact with this melt, and gradually pulling up the seed crystal. be.

However, such an FZ method has a problem in that a long single crystal fiber with a small diameter cannot be obtained. That is,
In general, in crystal growth methods such as the FZ method described above, the outer diameter of the single crystal fiber is determined by the relationship between the surface tension of the melt at the end of the mother crystal and the melt holding power of the pulling seed crystal. Since it is limited to about 1/3 of the diameter, in order to obtain a long single crystal fiber with a small diameter, it is necessary to make the mother crystal thinner and longer. However, this FZ method has the problem that when the seed crystal is pulled up, the crystal axis tends to curve, especially when the parent crystal has a small diameter, making it impossible to obtain a parent crystal with a straight crystal axis. Therefore, since there is a limit to the length of the mother crystal that can be obtained, there is also a limit to the length of the single crystal fiber that can be obtained by pulling one step from such a mother crystal.

On the other hand, methods that can lengthen single-crystal fibers include melt-pulling method (Czochralski method: hereinafter referred to as CZ method), E F G (Edge-de-pulling method),
There is a fine film-fed Growth) method. According to these drawing methods, a starting material such as an organometallic compound is filled in a molten state in a melting crucible, and in the CZ method, a seed crystal is brought into direct contact with this melt, and in the EFG method, a cylindrical shape immersed in the melt is brought into direct contact with the melt. A long single-crystal fiber is obtained by bringing a seed crystal into contact with the upper end opening of the die and pulling up the seed crystal.Furthermore, by appropriately supplying the melt into the melting crucible, the single-crystal fiber is produced. Continuous production is possible, and single crystal fibers can be easily made longer.

However, in all of these methods, the outer diameter of the obtained single crystal fiber tends to fluctuate, and this outer diameter variation causes a problem in that the quality of the single crystal fiber deteriorates.

"Means for Solving the Problems" Therefore, in this invention, a cylindrical host crystal rod is prepared as a precursor of single crystal phino, and the outer circumference of the host crystal rod is etched to change the outer diameter of the rod. The above problem was solved by controlling and melting the end of the host crystal rod and continuously pulling the single crystal fiber.

In this invention, a seed crystal is brought into contact with a starting material melt and grown to produce a host crystal rod 1.

Starting materials include metal oxides such as L+NbO3 and LiTaO3, YAG, Nd-YAG%YIG, and GSGG (
gadolinium, scandium, gallium, garnet)
Compound semiconductors such as sapphire, alumina crystals such as ruby, etc. are preferably used, but the material is not limited thereto. Further, as a method for producing the above-mentioned mother crystal rod 1, for example, a method of producing a precursor base material 2 of the mother crystal rod 1 as shown in FIG. 1 is used. That is, the precursor base material 2 is obtained by cutting and polishing a large-diameter polycrystal or single crystal made of, for example, the above-mentioned metal oxide, metal oxyacid, etc., to a predetermined size using a grinder or the like.

Then, the upper end of this precursor base material 2 is heated and melted using an appropriate heating means such as a micro burner, and a seed crystal of a predetermined size is brought into contact with this melt and the seed crystal is pulled up to form a base crystal rod. 1 are produced continuously.

Next, the outer periphery of the thus obtained host crystal rod 1 is etched to continuously control the outer diameter of the rod. For this outer diameter control, as shown in FIG.
control the outer diameter within a predetermined range. Here, as the outer diameter measuring device 3, a laser type outer diameter measuring device, an outer diameter measuring device using backscattered light, a measuring system using a measuring television camera, etc. are suitably used. Furthermore, a gas phase etching device is used as the outer diameter control device 4. Etching gases used in this gas phase etching apparatus include F7, Cb
Gases containing halogen compounds such as , B rt , HF 1CF 4 and CCQtPt are suitable, and heating sources for these etching gases include micro burners, excimer lasers, argon gas lasers, carbon dioxide lasers, dye lasers, YAG lasers, etc. Various lasers, arc imaging, etc. can be used.

Next, the mother crystal rod l whose outer diameter is controlled in this way
is sent upward by a delivery belt 5.5, and the upper end of this mother crystal rod l is heated and melted by heating means 6 using a carbon dioxide laser, for example, and a seed crystal of a predetermined size is brought into contact with this melted portion. By continuously pulling this seed crystal upward by a pulling belt 7.7, a desired single crystal fiber 8 with a stable outer diameter is obtained.

According to this method, a host crystal rod 1 is produced as a precursor of a single crystal fiber 8, and the outer circumference of the host crystal rod 1 is etched to control the outer diameter of the rod while the end of the host crystal rod 1 is etched. Since the single crystal fiber 8 is continuously pulled up from
A high quality single crystal fiber 8 with a stable outer diameter can be obtained from the above. Further, by performing the manufacturing process of the host crystal rod l and controlling its outer diameter in several stages, it is possible to continuously manufacture a long single crystal fiber 8 with a small diameter.

In the above embodiment, the curved part base material 2 was created to obtain the host crystal rod 1, but the host crystal rod 1 may also be created using, for example, the CZ method or the EFG method.

That is, in the CZ method, as shown in FIG. 2, a starting material is melted in a crucible 9, and a seed crystal is brought into direct contact with this melt 10 and pulled up to obtain a host crystal rod 1. Also, E
In the FG method, as shown in FIG. 3, a seed crystal is brought into contact with a starting material melt 10 that has been cleared in a crucible 9 through a die 11 of a predetermined size and pulled up to obtain a host crystal rod l. . In these methods, continuous production of small-diameter single crystal fiber 8 becomes possible by additionally supplying the starting material melt.

"Example" A cylindrical host crystal rod made of Cr-doped sapphire was pulled up by the EFG method using a cylindrical die (made of molybdenum) with an outer diameter of I, an inner diameter of 0.7 Rm, and a length LOxx.
When the outer diameter of this host crystal rod was continuously measured, the outer diameter varied within a range of 0.8 to 1.2 yR. Next, based on the above measurement data, the outer diameter of the host crystal rod was controlled by gas etching. That is,
Laser light from a carbon dioxide gas laser with an output of 8 W is focused on the surface of the host crystal rod in a circular area with a diameter of 40 μm, and this area is heated to a temperature of about 1200 to 1600°C, and CCσF, CCσF, Etching gas (10 cc/min) is mixed with carrier gas (Ar gas 2
0cc/min). By changing the laser output, the etching rate was adjusted to 10 to 40μ.
It was controlled within the range of 1/min. With this etching process,
The outer diameter of the host crystal rod could be controlled to 750±10 μm, and a single crystal fiber of stable quality and an external volume of 250 μl was obtained from this host crystal rod.

"Effects of the Invention" As explained above, according to this invention 7, a host crystal rod is produced as a precursor of a single crystal fiber, and the outer circumference of the host crystal rod is etched to control the outer diameter of the rod. Since the single crystal fiber is continuously pulled up from the end of the mother crystal rod, a high quality single crystal fiber with a stable outer diameter can be obtained from the mother crystal rod whose outer diameter is controlled.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing a first embodiment of the present invention, FIG. 2 is a partially omitted schematic block diagram showing a second embodiment of the present invention, and FIG. 3 is a schematic block diagram showing a second embodiment of the present invention. FIG. 3 is a partially omitted schematic configuration diagram showing a third embodiment. l...Mother crystal rod, 8...Single crystal fiber.

Claims (1)

[Claims] A seed crystal is brought into contact with the starting material melt and allowed to grow to produce a host crystal rod, and the outer periphery of the host crystal rod is etched to control the outer diameter of the rod while melting the end of the host crystal rod. 1. A method for manufacturing a single crystal fiber, which comprises continuously pulling a single crystal fiber.