A gas raw material supply device and method for optical fiber preform deposition

Abstract

The present invention relates to a gas raw material supply device and method for optical fiber preform deposition, including an evaporation cabinet and a flow mixing cabinet, wherein an evaporation bottle is installed in the evaporation cabinet, wherein an MFC is installed in the flow mixing cabinet, wherein the evaporation bottle includes a SiCl4 evaporation bottle and a GeCl4 evaporation bottle, wherein each gas raw material evaporation bottle is respectively provided with a bottle heating device, wherein each gas raw material evaporation bottle is respectively connected to an MFC input port in the flow mixing cabinet through an air delivery pipeline, wherein an output port of the MFC is connected to a mixed gas delivery pipeline, wherein two SiCl4 and two GeCl4 evaporation bottles are respectively provided, wherein the feed ports of the two evaporation bottles are respectively connected to a feed pipeline through a control valve, wherein the air delivery ports of the two evaporation bottles are respectively connected to a SiCl4 air delivery pipeline through a control valve or a switching valve. The present invention has a reasonable and simple structural arrangement, which can not only provide continuous and uninterrupted gas raw materials, but also has stable air pressure, thereby improving the production efficiency of the equipment.

Description

Technical Field

[0001] The present invention relates to a gas raw material supply device and method for optical fiber preform deposition, belonging to the technical field of optical fiber preform processing equipment. Background Art

[0002] In recent years, with the accelerated construction of domestic 5G, the demand for optical fiber cables in the communication market is continuously increasing. As an indispensable part of 5G construction, optical fiber cables are playing an increasingly important role in the 5G communication network. Optical fibers are drawn from preforms, so the preform manufacturing technology plays a crucial role in the production of optical fibers. Most of the existing optical fiber preforms are made by chemical vapor deposition. For chemical vapor deposition, the raw material silicon-germanium compounds participating in the chemical reaction are converted into gas raw materials through heating and evaporation, and then a constant gas supply pressure needs to be maintained for the gas raw materials during the deposition process. The stability of the raw material gas supply pressure will have a great impact on the deposition quality of the preform, and the stability of the reaction gas raw material pressure is mainly achieved through a heating and evaporation device. The existing heating and evaporation devices generally have a single evaporation bottle structure and heat the evaporation bottle through a simple heating method. On the one hand, the pressure of this device is not stable enough; on the other hand, after the raw materials are used up, the evaporation bottle needs to be refilled and pumped. During the refilling and pumping process, the gas supply is interrupted and the entire device stops running. Such a discontinuous gas raw material supply method seriously affects the processing efficiency of optical fiber preform deposition and the equipment utilization efficiency. In addition, during the transmission of the gas raw material, i.e., silicon-germanium compound vapor, in the existing gas raw material supply device, gas condensation is very likely to occur. Once the gas condenses, it will cause fluctuations in the MFC (mass flow controller) at least, and damage the MFC at worst. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a gas raw material supply device and method for optical fiber preform deposition in view of the above-mentioned deficiencies of the existing technology. Its structure is reasonably and simply arranged, which can not only provide continuous gas raw materials, but also has stable air pressure, improving the production efficiency of the equipment.

[0004] The technical solution of the supply device adopted by the present invention to solve the above-mentioned problems is as follows:

[0005] It includes an evaporation cabinet and a flow mixing cabinet. An evaporation material bottle is installed in the evaporation cabinet, and an MFC (gas flowmeter) is installed in the flow mixing cabinet. The evaporation material bottle includes a SiCl4 evaporation material bottle and a GeCl4 evaporation material bottle. Each gas raw material evaporation material bottle is respectively equipped with a bottle heating device. Each gas raw material evaporation material bottle is respectively connected to the MFC input port in the flow mixing cabinet through a gas supply pipeline. The output port of the MFC is connected to the mixed gas transmission pipeline. It is characterized in that there are two SiCl4 evaporation material bottles. The feed ports of the two SiCl4 evaporation material bottles are respectively connected to the feed pipeline through control valves. The gas supply ports of the two SiCl4 evaporation material bottles are respectively connected to the SiCl4 gas supply pipeline through control valves or switching valves. There are two GeCl4 evaporation material bottles. The feed ports of the two GeCl4 evaporation material bottles are respectively connected to the feed pipeline through control valves. The gas supply ports of the two GeCl4 evaporation material bottles are respectively connected to the GeCl4 gas supply pipeline through control valves or switching valves.

[0006] According to the above solution, an evaporation cabinet heater for keeping the temperature in the cabinet constant is installed in the evaporation cabinet, and a mixing cabinet heater for keeping the temperature in the cabinet constant is installed in the flow mixing cabinet.

[0007] According to the above solution, the evaporation material bottle is provided with a pressure sensor and a liquid level sensor.

[0008] According to the above solution, a transmission pipeline heating tape is installed on the gas supply pipeline.

[0009] According to the above solution, a mixed gas transmission pipeline heating tape is installed on the mixed gas transmission pipeline.

[0010] According to the above solution, the bottle heating device includes a bottle side wall heating blanket and a bottle bottom heating blanket.

[0011] According to the above solution, a suction port is arranged at the upper end of the evaporation material bottle. The suction port is connected to a vacuum pump through a control valve and a suction pipeline.

[0012] The technical solution of the gas raw material supply method of the present invention is as follows:

[0013] Using the supply device of the present invention, the material in the liquid raw material tank is pressed into the SiCl4 evaporation bottle and the GeCl4 evaporation bottle through N2. After the feeding is completed, the evaporation cabinet and the evaporation bottles start to be heated. At this time, the control valve of the air supply pipeline is closed. When the liquid raw material is heated in the evaporation bottle, the temperature rises slowly, and the pressure in the evaporation bottle also rises. The pressure sensor in the evaporation bottle monitors the pressure in the evaporation bottle in real time. At the same time, the N2 mixed in the evaporation bottle is pumped out through the vacuum pump to keep the material pressure in the evaporation bottle stable and maintained at the saturated vapor pressure. At this time, the control valve of the air supply pipeline of one evaporation bottle of each gas raw material is opened, and the SiCl4 and GeCl4 vapor of the gas raw material are transmitted to the MFC cabinet through the air supply pipeline, and enter the mixed gas transmission pipeline through the output port of the MFC for production air supply. The control valve of the air supply pipeline of the other evaporation bottle of each gas raw material is closed as a standby evaporation bottle, and the above feeding heating and N2 pumping process is carried out before the production air supply. When the previous evaporation bottle is about to be used up, through switching, the control valve of the air supply pipeline of the other evaporation bottle is opened for use, and the control valve of the air supply pipeline of the previous evaporation bottle is closed. The two evaporation bottles of each gas raw material are used alternately in a cycle to maintain the continuous gas raw material supply to the deposition system until the deposition is completed.

[0014] According to the above scheme, the evaporation cabinet is heated by the evaporation cabinet heater to keep the temperature in the cabinet constant, the flow mixing cabinet is heated by the mixing cabinet heater to keep the temperature in the cabinet constant, the air supply pipelines are heated by the transmission pipeline heating tape to keep the temperature of the air supply pipelines constant, and the mixed gas transmission pipeline is heated by the mixed gas transmission pipeline heating tape to keep the temperature of the mixed gas transmission pipeline constant.

[0015] According to the above scheme, the heating temperature of the SiCl4 evaporation bottle is set to 30 - 50 °C, the heating temperature of the GeCl4 evaporation bottle is set to 30 - 55 °C, and the heating temperature in the evaporation cabinet is set to 30 - 50 °C.

[0016] According to the above scheme, the air supply pipeline includes the SiCl4 air supply pipeline and the GeCl4 air supply pipeline. The raw material vapor is transmitted to the flow mixing cabinet through the air supply pipeline with a heating tape. The SiCl4 air supply pipeline is heated in two sections. One section is in the evaporation cabinet, and the temperature of this section of the pipeline is set to 30 - 55 °C. The other section of the heating tape is from the evaporation cabinet to the flow mixing cabinet, and the temperature of this section of the pipeline is set to 32 - 57 °C. The GeCl4 air supply pipeline is heated in two sections. One section is in the evaporation cabinet, and the temperature of this section of the pipeline is set to 30 - 55 °C. The other section of the heating tape is from the evaporation cabinet to the flow mixing cabinet, and the temperature of this section of the pipeline is set to 32 - 60 °C.

[0017] According to the above solution, the heating temperature in the flow mixing cabinet is 0 - 15°C higher than the temperature of the air supply pipeline, and the heating temperature of the mixed gas delivery pipeline is 0 - 15°C higher than the temperature of the flow mixing cabinet.

[0018] The beneficial effects of the present invention are as follows: 1. The structure is reasonably and simply arranged. In particular, the double evaporation material bottle structure is set so that the feeding is uninterrupted, and continuous and uninterrupted gas raw material supply can be carried out, thereby ensuring the continuous and stable deposition of the optical fiber preform, greatly improving the production efficiency of the equipment, and at the same time, the volume of the evaporation material bottle can be correspondingly reduced, making the equipment structure more compact; 2. By setting heaters and heating tapes in the evaporation cabinet, flow mixing cabinet, air supply pipeline, and mixed gas delivery pipeline, the problems of unstable material pressure and steam condensation during the air supply process can be effectively solved, so that the raw material steam in the air supply pipeline and the mixed gas delivery pipeline maintains a constant pressure and state, reducing the fluctuation of the MFC (gas flow meter), thereby effectively improving the deposition quality of the optical fiber preform; 3. By setting the MFC, pressure sensor, and liquid level sensor, the flow rate of the silicon-germanium compound can be monitored and controlled in real time, the raw material content during the deposition process can be accurately controlled, and the refractive index profile accuracy of the deposited core rod can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be further described in detail below with reference to the drawings and embodiments.

[0021] An embodiment of the device of the present invention is as Figure 1As shown in the figure, it includes an evaporation cabinet 1, and an evaporation cabinet heater 2 is installed inside the evaporation cabinet. The evaporation cabinet heater can heat the entire evaporation cabinet. There are 4 evaporation material bottles 3 installed inside the evaporation cabinet. The 4 evaporation material bottles include 2 SiCl4 evaporation material bottles and 2 GeCl4 evaporation material bottles. The feeding ports of the two SiCl4 evaporation material bottles are respectively connected to the GeCl4 feeding pipeline through control valves 101 and 103. The gas supply ports of the two SiCl4 evaporation material bottles are respectively connected to the SiCl4 gas supply pipeline through control valves 102 and 104. The feeding ports of the two GeCl4 evaporation material bottles are respectively connected to the GeCl4 feeding pipeline through control valves 105 and 107. The gas supply ports of the two GeCl4 evaporation material bottles are respectively connected to the GeCl4 gas supply pipeline through control valves 106 and 108. The cross-sectional area of the SiCl4 evaporation material bottle can be 1500 square centimeters, and the cross-sectional area of the GeCl4 evaporation material bottle is 800 square centimeters. A pressure sensor 4 and a liquid level sensor 5 are installed in each evaporation material bottle, and a material bottle heating device is respectively configured. The material bottle heating device includes a material bottle side wall heating blanket 6 and a material bottle bottom heating blanket 7. The material bottle side wall heating blanket and the material bottle bottom heating blanket are integrated with temperature measuring probes inside. The temperature measuring probes are heat-sensitive elements and can perform accurate temperature measurement. The heating blankets can be respectively controlled in temperature through a temperature controller and the temperature can be set separately. The temperature controller is a digital electronic temperature controller and can perform digital quantization control on the temperature. The material bottle side wall heating blanket and the material bottle bottom heating blanket also have heat preservation and heat insulation layers at the same time. The liquid level sensor 5 can collect and display the liquid level in the material bottle and transmit the liquid level information to the temperature controller. The temperature controller controls the material bottle side wall heating blanket and the material bottle bottom heating blanket according to the temperature measuring probe and the liquid level. The gas supply pipeline is provided with a transmission pipeline heating belt. The SiCl4 gas supply pipeline is divided into two sections of heating belts. One section of heating belt 8 is inside the evaporation cabinet, and the other section of heating belt 9 is from the evaporation cabinet to the flow mixing cabinet. The GeCl4 gas supply pipeline is divided into two sections of heating. One section of heating belt 10 is inside the evaporation cabinet, and the other section of heating belt 11 is from the evaporation cabinet to the flow mixing cabinet. The partition heating belt can be respectively controlled in temperature through a temperature controller and the temperature can be set separately. The SiCl4 and GeCl4 vapors are transmitted to the flow mixing cabinet 12 through the gas supply pipeline with heating belts. The flow mixing cabinet is provided with an MFC (gas flowmeter) and a mixing cabinet heater 13 for keeping the temperature in the cabinet constant. The mixing cabinet heater can heat the entire flow mixing cabinet and the temperature is controlled separately. The two gas raw material evaporation material bottles are respectively connected to the input ports of the MFC in the flow mixing cabinet through the gas supply pipeline. The raw material gas passes through the MFC and then from the output port through control valves 113 and 114 and then through the main control valve 117 to converge to the mixed gas transmission pipeline. The mixed gas transmission pipeline is installed with a heating belt 14. The heating belt 14 can be respectively controlled in temperature through a temperature controller and the temperature can be set separately.In the flow mixing cabinet, the MFC can set two or more standby MFCs for use as spares or for connecting other raw material gases. The output ports of the standby MFCs are connected to the master control valve 117 through control valves 115 and 116. In addition, a suction port is provided at the upper end of the evaporation material bottle, and the suction port is connected to a vacuum pump (pump) through a control valve 118 and a suction pipeline.

[0022] The method for supplying the gas raw materials of the present invention is as follows: The materials in each raw material tank are respectively pressed into a SiCl4 evaporation material bottle and a GeCl4 evaporation material bottle through N2 (nitrogen). The liquid level gauge 5 of the evaporation material bottle monitors the liquid level in real time. When the liquid level reaches 90%, the filling of the material is automatically stopped. After the evaporation cabinet 1 is powered on, the bottom heating blanket 7, the side wall heating blanket 6 of the 4 evaporation material bottles and the heater 2 in the evaporation cabinet start to heat. The temperature of the heater 2 in the evaporation cabinet is set to 45 °C, the bottom and side wall temperatures of the SiCl4 evaporation material bottle are set to 46 °C and 45 °C respectively, and the bottom and side wall temperatures of the GeCl4 evaporation material bottle are set to 48 °C and 47 °C. When the raw materials are heated in the evaporation material bottle, the temperature of the liquid raw materials will slowly rise, and the pressure in the evaporation material bottle will also rise accordingly. The pressure sensor 4 of the evaporation material bottle monitors the pressure in the material bottle in real time. At this time, the evaporation material bottle is pumped by a vacuum pump. The pumping can extract the N2 mixed into the material bottle to stabilize the material pressure in the evaporation material bottle. Generally, the pumping will take 10 - 40 hours. After the pumping is completed, all the liquids in the evaporation material bottle will be heated to the set temperature and maintained. At this time, the SiCl4 material pressure will be maintained at 600 ± 10 mbar, and the GeCl4 material pressure will be maintained at 220 ± 10 mbar. At this time, the evaporation material bottle can be put into production use, and the liquid level gauge 5 of the evaporation material bottle monitors the height of the raw materials in the material bottle in real time. Another standby evaporation material bottle can start filling and pumping. When the liquid level of the evaporation material bottle drops to 20%, the pressure of the standby evaporation material bottle has also stabilized and can be put into production. By switching the control valves, the two evaporation material bottles are used alternately in a cycle, ensuring the continuity of the deposition production.

[0023] After the evaporation material bottle is put into production and use, the SiCl4 and GeCl4 vapors are transported through a pipeline with a heating tape to a flow mixing cabinet equipped with an MFC. The SiCl4 transport pipeline is heated in two sections. One section is inside the evaporation cabinet, and the temperature of this section of the pipeline is set at 48 °C. The other section of the pipeline is set from the evaporation cabinet to the flow mixing cabinet, and the temperature of this section of the pipeline is set at 50 °C. The GeCl4 transport pipeline is heated in two sections. One section is inside the evaporation cabinet, and the temperature of this section of the pipeline is set at 50 °C. The other section of the pipeline is set from the evaporation cabinet to the flow mixing cabinet, and the temperature of this section of the pipeline is set at 52 °C. The temperature of the heater in the flow mixing cabinet is set at 54 °C. After the raw material gases are mixed in the flow mixing cabinet, they are transported through a mixed gas transport pipeline with a heating tape to the gas end chuck of the PCVD. The temperature of the heating tape of the mixed gas transport pipeline is set at 55 °C. By setting the temperature of the evaporation system through the method of the present invention, on the one hand, the pressures of SiCl4 and GeCl4 can be kept stable during the production process, avoiding steam condensation. On the other hand, continuous production can be achieved, greatly improving the production efficiency.

Claims

1. A gas raw material supply device for optical fiber preform deposition, comprising an evaporation cabinet and a flow mixing cabinet. An evaporation material bottle is installed in the evaporation cabinet, and an MFC is installed in the flow mixing cabinet. The evaporation material bottle includes a SiCl4 evaporation material bottle and a GeCl4 evaporation material bottle. Each gas raw material evaporation material bottle is respectively equipped with a bottle heating device. Each gas raw material evaporation material bottle is respectively connected to the input port of the MFC in the flow mixing cabinet through a gas supply pipeline. The output port of the MFC is connected to a mixed gas delivery pipeline, and it is characterized in that There are two SiCl4 evaporation material bottles. The feed inlets of the two SiCl4 evaporation material bottles are respectively connected to the feeding pipeline through control valves. The gas supply ports of the two SiCl4 evaporation material bottles are respectively connected to the SiCl4 gas supply pipeline through control valves or switching valves. There are two GeCl4 evaporation material bottles. The feed inlets of the two GeCl4 evaporation material bottles are respectively connected to the feeding pipeline through control valves. The gas supply ports of the two GeCl4 evaporation material bottles are respectively connected to the GeCl4 gas supply pipeline through control valves or switching valves. An evaporation cabinet heater for keeping the temperature in the cabinet constant is installed in the evaporation cabinet. A mixing cabinet heater for keeping the temperature in the cabinet constant is installed in the flow mixing cabinet. A suction port is arranged at the upper end of the evaporation material bottle. The suction port is connected to a vacuum pump through a control valve and a suction pipeline. A suction port is arranged at the upper end of the evaporation material bottle. The suction port is connected to a vacuum pump through a control valve and a suction pipeline.

2. The gas raw material supply device for optical fiber preform deposition according to claim 1, characterized in that A pressure sensor and a liquid level sensor are arranged on the evaporation material bottle.

3. The gas raw material supply device for optical fiber preform deposition according to claim 1 or 2, characterized in that A transmission pipeline heating tape is installed on the gas supply pipeline.

4. The gas raw material supply device for optical fiber preform deposition according to claim 1 or 2, characterized in that A mixed gas transmission pipeline heating tape is installed on the mixed gas transmission pipeline.

5. The gas raw material supply device for optical fiber preform deposition according to claim 1 or 2, characterized in that The material bottle heating device includes a material bottle side wall heating blanket and a material bottle bottom heating blanket.

6. A gas raw material supply method for optical fiber preform deposition, characterized in that Using any of the supply devices of claims 1-5, the material in the liquid raw material tank is pressed into the SiCl4 evaporation material bottle and the GeCl4 evaporation material bottle through N2. After the feeding is completed, the evaporation cabinet and the evaporation material bottle start to be heated. At this time, the control valve of the gas supply pipeline is closed. When the liquid raw material is heated in the evaporation material bottle, the temperature rises slowly, and the pressure in the evaporation material bottle also rises. The pressure sensor of the evaporation material bottle monitors the pressure in the evaporation material bottle in real time. At the same time, the N2 mixed in the evaporation material bottle is pumped out through the vacuum pump to make the material pressure in the evaporation material bottle stable and maintain it at the saturated vapor pressure. At this time, the control valve of the gas supply pipeline of one evaporation material bottle of each gas raw material is opened. The SiCl4 and GeCl4 vapor of the gas raw material are transmitted to the MFC cabinet through the gas supply pipeline, and enter the mixed gas transmission pipeline through the output port of the MFC for production gas supply. The control valve of the gas supply pipeline of the other evaporation material bottle of each gas raw material is closed as a standby evaporation material bottle, and the above feeding heating and N2 pumping process are carried out before the production gas supply. When the previous evaporation material bottle is about to be used up, through switching, the control valve of the gas supply pipeline of the other evaporation material bottle is opened for use, and the control valve of the gas supply pipeline of the previous evaporation material bottle is closed. The two evaporation material bottles of each gas raw material are used alternately in a cycle to keep the continuous gas raw material supply to the deposition system until the deposition is completed. The evaporation cabinet is heated by the evaporation cabinet heater to keep the temperature in the cabinet constant. The flow mixing cabinet is heated by the mixing cabinet heater to keep the temperature in the cabinet constant. The gas supply pipelines are heated by the transmission pipeline heating tape to keep the temperature of the gas supply pipelines constant. The mixed gas transmission pipeline is heated by the mixed gas transmission pipeline heating tape to keep the temperature of the mixed gas transmission pipeline constant.

7. The gas raw material supply method for optical fiber preform deposition according to claim 6, characterized in that The heating temperature of the SiCl4 evaporation material bottle is set at 30 - 50 °C, the heating temperature of the GeCl4 evaporation material bottle is set at 30 - 55 °C, and the heating temperature inside the evaporation cabinet is set at 30 - 50 °C.

8. The gas raw material supply method for optical fiber preform deposition according to claim 6, characterized in that The gas supply pipeline includes a SiCl4 gas supply pipeline and a GeCl4 gas supply pipeline. The raw material vapor is transported to the flow mixing cabinet through the gas supply pipeline with heating tapes. The SiCl4 gas supply pipeline is heated in two sections. One section is inside the evaporation cabinet, and the temperature of this section of the pipeline is set at 30 - 55 °C. The other section of the heating tape is from the evaporation cabinet to the flow mixing cabinet, and the temperature of this section of the pipeline is set at 32 - 57 °C. The GeCl4 gas supply pipeline is heated in two sections. One section is inside the evaporation cabinet, and the temperature of this section of the pipeline is set at 30 - 55 °C. The other section of the heating tape is from the evaporation cabinet to the flow mixing cabinet, and the temperature of this section of the pipeline is set at 32 - 60 °C.

9. The gas raw material supply method for optical fiber preform deposition according to claim 8, characterized in that The heating temperature inside the flow mixing cabinet is 0 - 15 °C higher than the temperature of the gas supply pipeline, and the heating temperature of the mixed gas transmission pipeline is 0 - 15 °C higher than the temperature of the flow mixing cabinet.

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