JPS5930658B2 - Method for manufacturing cylindrical glass with radially varying refractive index - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a glass preform for making a self-focusing fiber for optical communications.

Figure 1 shows how a soot laminate is synthesized using a single nozzle to produce glasses with different refractive indexes in the radial direction. 1 is a soot laminate, 2 is a nozzle for soot synthesis, and 3 is a soot laminate nozzle. Indicates suit. As shown in the figure, the soot synthesis nozzle 2 is reciprocated in the radial direction of the disc-shaped starting member 5 at a constant speed. On the other hand, the composition and amount of the soot 3 synthesized by the nozzle are periodically changed in synchronization with the reciprocating movement of the nozzle, and the soot is sprayed onto the rotating starting member 5, thereby stacking the soot. The reason why the amount of soot to be synthesized increases as the nozzle moves toward the outer periphery is to maintain the layered soot thickness at a constant thickness. Soot raw materials are usually SiCl4, GeCl4, BBr
3. Glass-forming halides such as POCl3 are used, and these raw materials are made into a vapor state with gases such as O2, N2, Ar, etc. and transported to the soot synthesis nozzle. The soot synthesis nozzle is used to oxidize glass-forming halides at high temperatures, or to oxidize Ho, O. This is a nozzle for synthesizing soot by flame hydrolysis with gas. The disc-shaped starting member is rotated and lowered depending on the amount of soot stacked. The soot layered in a predetermined amount is sintered in a high-temperature furnace to become transparent and vitrified. FIG. 2 shows an example in which a plurality of nozzles, for example two nozzles, are used. Soots with different compositions are synthesized from each nozzle, but in this case, 1
The composition of the soot synthesized by the main nozzle does not need to be changed over time, and the soot 3-i, 3 synthesized by each nozzle 2-i, 2-゛ is synchronized with the reciprocating movement of the nozzle.
The relative amount of -ii is changed. Nozzle 2-i, 2-ii
are both moved radially at the same speed, and the disc-shaped starting member is rotated and lowered as the soot grows.

Example 1 In order to synthesize a SiO2-GeO2 binary glass with a refractive index change in the radial direction, SlC was used as a raw material.
Using SiCl4 and GeCl4, and using 02 as a carrier gas, the ratio α of carrier gas sent to both hubs (Ra1) and the carrier gas amount V for SiCl4 were changed periodically as shown in Fig. It was fed into the nozzle (oxygen hydrogen burner).

The bubbler temperature of SiCl4 and GeCl4 is 20
℃, and 40℃.

α is varied from 0 to 0.4, and V is O.
The speed was changed to 200 sccm.

On the other hand, the nozzle was reciprocated in the radial direction of a starting member made of quartz glass with a diameter of 10 (1771) at a speed of 5 CTIL/min, and synchronized so that when the nozzle was at the center position, V1-0, α-0.4. The synthesized SiO2-GeO2 fine powder was hydrolyzed in the flame of the burner and sprayed onto the starting member in this way.The starting member was rotated at a constant speed and lowered according to the amount of soot stacked. In this way, a cylindrical soot body with a diameter of about 10 CT!L1 length of about 30 cm was made, and this was lowered into a sintering furnace at about 1550°C and under a N2 atmosphere at a descending speed of 2 mm/min. When the glass was made transparent, a transparent glass having a cross-sectional refractive index distribution similar to the carrier gas ratio shown in FIG. 3 and having a diameter of about 6 and a length of about 20 was obtained.
Example 2 In order to synthesize a Si02-GeO2 binary glass with a refractive index change in the radial direction, we used SlC as a raw material.
14 and GeCl4, and Ar as the carrier gas.
Each raw material was guided to the respective soot synthesis nozzle using a soot, a high-temperature oxidation reaction was caused, and the resulting fine particulate glass (soot) of SiO2 and GeO2 was blown onto a disc-shaped starting member.

At this time, the bubbler temperatures of SiCl4 and GeCl4 were set to 20°C and 40°C, respectively.

The amount of raw material gas introduced to the nozzle is Vl and V2, respectively.
Then, it was changed periodically as shown in FIG. on the other hand,
The two nozzles are moved back and forth in the radial direction at a speed of 5 cTrL/min, and when the nozzles reach the center position, V1 = 0, 2.
Example 1 is the starting member synchronized so that = 40 sccm
I used the same thing and did the same operation.

The obtained soot body was made transparent by the same operation as in Example 1.
A glass cylinder with a cross-sectional refractive index distribution varying in the radial direction was obtained.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams for synthesizing a glass soot laminate according to the present invention, and FIGS. 3 and 4 show the relationship between the nozzle position and the gas amount. 1: Glass soot laminate, 2-1, 2-11: Nozzle,
3-[, 3-[1: Soot, 4-1, 4-11: Indicates the moving direction of the nozzle. 5: Indicates starting member.

Claims (1)

[Claims] 1 When the nozzle for synthesizing soot through a gas-phase reaction of raw materials is periodically moved in parallel in the radial direction of the target at a constant velocity to produce layered growth in the direction of the rotational axis of the target, the smaller of the soot composition or the amount of soot sprayed is The refractive index changes in the radial direction, which is characterized by laminating soot in a cylindrical shape whose composition changes in the radial direction by periodically changing one of the soots in synchronization with the reciprocating movement of the nozzle, and making this transparent. Method for manufacturing cylindrical glass.