Device and method for growing sapphire single crystal optical fiber cladding by utilizing Mist-CVD (Chemical Vapor Deposition) with vertical structure

Abstract

The invention provides a device and a method for growing a sapphire single crystal optical fiber cladding by utilizing Mist-CVD (Chemical Vapor Deposition) of a vertical structure. The device comprises an atomized particle generation device, a reaction chamber, a carrier gas control device, a carrier gas bottle and an exhaust device, the atomized particle generation device converts the prepared precursor solution into small fog drops, the small fog drops are sent into the reaction chamber through carrier gas to be heated, the small fog drops form a cladding on the single crystal optical fiber, and finally tail gas is exhausted through gas extraction equipment. The method is easy to operate, deposition of the cladding can be rapidly completed by adopting Mist-CVD equipment of a vertical structure, and compared with cladding preparation methods such as a coating method, the experiment time can be shortened, and the uniformity of cladding preparation can be guaranteed.

Description

Technical Field

[0001] The present invention relates to a device and a method for growing a sapphire single crystal optical fiber cladding by using a Mist-CVD with a vertical structure, belonging to the technical field of single crystal optical fiber cladding preparation. Background Art

[0002] Single-crystal fiber is a novel optical material with a fiber-optic waveguide structure. It combines the advantages of both crystals and optical fibers, offering the excellent optical and physical properties of bulk single crystals with the high heat dissipation efficiency of glass fiber. Single-crystal fiber holds significant potential for applications in high-power laser output and high-temperature detection.

[0003] Single-crystal optical fibers are often used in high-temperature sensors, requiring prolonged exposure to harsh environments such as high temperatures. This can damage the fiber surface or interior, exacerbating scattering losses and compromising optical performance. Therefore, fabricating high-quality fiber cladding is a key challenge in the single-crystal optical fiber field. The concept of single-crystal optical fiber cladding originates from glass cladding, which involves coating the outer layer of the fiber with a material with a lower refractive index than the fiber itself to reduce scattering losses and improve light transmission efficiency. This facilitates long-distance optical waveguides and high-power laser output, and coated glass fibers are widely used in the laser field. Currently, glass fiber lasers can achieve multi-watt mid-infrared laser output. Although the fabrication process for glass fiber cladding is mature, its instability at high temperatures and susceptibility to chemical attack under certain environmental conditions hinder its application in harsh sensing environments. Therefore, to expand the operating range of sensors, we have turned our attention to sapphire single-crystal optical fibers, which offer superior chemical and thermal stability and can withstand temperatures exceeding 1000°C.

[0004] Coating crystal fibers is much more difficult than coating glass fibers. The refractive index of the sapphire fiber cladding must be lower than that of sapphire, while also having a thermal expansion coefficient close to that of sapphire to prevent peeling. The cladding material also needs to be thermochemically and mechanically stable. Currently, methods for preparing sapphire single-crystal fiber cladding primarily involve depositing a layer of material with a lower refractive index than that of sapphire on the outside of the fiber through vapor deposition or coating, and also through ion implantation to reduce the refractive index of the outer region of the fiber, thereby converting the outer region into a cladding. However, these methods have limitations, such as low efficiency of coating methods, high cost of ion implantation, and problems with hydrogen ion diffusion at high temperatures. Therefore, further research is needed to explore methods for preparing sapphire single-crystal fiber.

[0005] Mist-CVD (Mist-CVD) is now commonly used for epitaxial growth of oxide semiconductor thin films. This method does not require vacuum conditions, saving device costs and simplifying operating conditions. It also produces high-quality, uniform films. Therefore, developing a method for growing the cladding of sapphire single-crystal optical fibers using Mist-CVD is of great significance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention provides an apparatus and method for growing sapphire single-crystal optical fiber cladding using vertical Mist-CVD. This method addresses issues such as uneven cladding thickness and low density. Compared with existing sapphire single-crystal optical fiber cladding preparation methods, the present invention offers simplified operation, lower costs, and greater potential for widespread adoption.

[0007] The technical solutions of the present invention are as follows: A device for growing a sapphire single crystal optical fiber cladding using a vertical Mist-CVD process, the device comprising an atomized particle generating device, a reaction chamber, a carrier gas control device, a carrier gas bottle, and an exhaust device; A quartz tube is provided at the bottom center of the reaction chamber. The quartz tube is arranged vertically. The atomized particle generating device and the reaction chamber are arranged in a vertical structure. The top of the atomized particle generating device is connected to the lower end of the quartz tube via a pipe a. The atomized particle generating device is also connected to the carrier gas bottle via a pipe b. The pipe b is provided with a carrier gas control device. The reaction chamber is connected to an exhaust device through an exhaust port.

[0008] Preferably, according to the present invention, the quartz tube is open at both ends, the inner diameter of the quartz tube is larger than the diameter of the sapphire single crystal fiber and not smaller than the inner diameter of pipe a; the sapphire single crystal fiber is suspended at the center of the quartz tube using a clamp.

[0009] According to the preferred embodiment of the present invention, one end of the pipe a is arranged at the center position of the top of the atomized particle generating device, and the other end is arranged at the center position of the bottom of the reaction chamber; the pipe a is perpendicular to the reaction chamber; the inner diameter of the pipe a is not specifically limited, and is preferably larger than the diameter of the sapphire single crystal optical fiber.

[0010] Preferably, according to the present invention, the atomized particle generating device includes an ultrasonic transducer and a precursor solution storage chamber, the ultrasonic vibrator of the ultrasonic transducer generates ultrasonic waves and acts on the precursor solution to turn it into mist; the precursor solution storage chamber is located above the ultrasonic transducer; the material of the precursor solution storage chamber is plastic, corrosion-resistant steel or glass, and is used to store the precursor solution.

[0011] Preferably, according to the present invention, a resistance wire is provided outside the reaction chamber to achieve heating, and the resistance wire is connected to a temperature control device.

[0012] Preferably according to the present invention, the exhaust port is arranged at the upper part of the reaction chamber.

[0013] According to the present invention, the atomized particle generation device converts the prepared solution into small droplets for subsequent cladding growth. The reaction chamber is where the droplets are deposited on the single-crystal optical fiber to form the cladding. Based on the flow behavior of the atomized droplets within the reaction chamber, the temperature field and gas flow distribution are precisely controlled to achieve high-quality cladding. The carrier gas control device controls the type and flow rate of the incoming gas; the temperature control device controls the reaction temperature; and the exhaust device discharges the reacted gas to the outside.

[0014] According to the present invention, a method for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure comprises the following steps: Aluminum acetylacetonate and magnesium acetylacetonate are added to methanol to obtain a precursor solution; the precursor solution is placed in a precursor solution storage chamber of an atomized particle generating device to atomize the precursor solution into atomized droplets; carrier gas in a carrier gas tank is introduced into the atomized particle generating device through a carrier gas control device, so that the atomized droplets are pushed into a reaction chamber where a sapphire single crystal optical fiber is placed to react and obtain a cladding on the surface of the sapphire single crystal optical fiber; and finally, exhaust gas is discharged from an exhaust port through an exhaust device.

[0015] Preferably, according to the present invention, the concentration of aluminum acetylacetonate in the precursor solution is 0.02-0.06 mol / L, and the concentration of magnesium acetylacetonate is 0.02-0.06 mol / L.

[0016] Preferably, according to the present invention, the frequency of the ultrasonic transducer in the atomized particle generating device is 1.7-3 MHz.

[0017] Preferably according to the present invention, the carrier gas is argon, and the flow rate of the carrier gas is 2L / min-3L / min.

[0018] Preferably, according to the present invention, the sapphire single crystal optical fiber is pretreated before being placed in the reaction chamber. The specific steps are as follows: ultrasonically cleaning the sapphire single crystal optical fiber in methanol for 10 minutes, then ultrasonically cleaning it in deionized water for 10 minutes, and finally blowing off water droplets on the surface of the optical fiber with argon gas. After drying, it is placed in the reaction chamber for use; the diameter of the sapphire single crystal optical fiber is 300-400 μm and the length is 10-20 cm.

[0019] Preferably, according to the present invention, the reaction temperature is 400-600° C., and the reaction time is 60-90 min.

[0020] According to the present invention, the excellent mechanical strength of sapphire single-crystal optical fiber can meet the application requirements of many harsh environments. The cladding material on the sapphire optical fiber is selected as magnesium aluminum spinel. The cladding material of the single-crystal optical fiber must be chemically stable and have a refractive index slightly lower than that of sapphire to reduce scattering loss. At the same time, it must have a thermal expansion coefficient similar to that of the sapphire optical fiber to prevent the cladding from being peeled off. Magnesium aluminum spinel can basically meet the above requirements.

[0021] The technical features and beneficial effects of the present invention are as follows: 1. The method of the present invention is simple to operate. The vertical structure Mist-CVD equipment can quickly complete the deposition of the cladding. Compared with the cladding preparation methods such as the coating method, the experimental time is greatly shortened. In addition, the Mist-CVD method has low requirements for precursors and is easy to obtain.

[0022] 2. The vertical structure Mist-CVD equipment used in the method of the present invention can ensure the uniformity of cladding preparation, which is difficult to achieve with other methods. The use of vertical structure Mist-CVD to grow single crystal optical fiber cladding can solve the problems of long cladding preparation time and insufficient uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the vertical structure Mist-CVD equipment of the present invention for growing the cladding of a sapphire single crystal optical fiber.

[0024] Figure 2 This is an SEM image of the sapphire single crystal optical fiber with cladding grown in Example 2.

[0025] Among them: 1. carrier gas bottle; 2. pipeline b; 3. carrier gas control device; 4. atomized particle generation device; 5. pipeline a; 6. reaction chamber; 7. sapphire optical fiber; 8. quartz tube; 9. exhaust port; 10. exhaust device. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the following examples. The examples herein are only for explaining the present invention and are not intended to limit the present invention.

[0027] Example 1 A device for growing a sapphire single crystal optical fiber cladding using a vertical Mist-CVD process, the device comprising an atomized particle generating device 4, a reaction chamber 6, a carrier gas control device 3, a carrier gas bottle 1, and an exhaust device 10; A quartz tube 8 is provided at the bottom center of the reaction chamber 6. The quartz tube 8 is arranged vertically. The atomized particle generating device 4 and the reaction chamber 6 are arranged in a vertical structure. The top of the atomized particle generating device 4 is connected to the lower end of the quartz tube 8 via a pipe a 5; the atomized particle generating device 4 is connected to the carrier gas bottle 1 via a pipe b 2, and a carrier gas control device 3 is provided on the pipe b2; the pipe b 2 is a polytetrafluoroethylene (PTFE) hose.

[0028] The reaction chamber 6 is provided with an exhaust port 9 at the top, and the reaction chamber 6 is connected to an exhaust device 10 through the exhaust port 9; The quartz tube 8 is open at both ends. The inner diameter of the quartz tube 8 is larger than the diameter of the sapphire single crystal optical fiber and larger than the inner diameter of the pipe a 5. The inner diameter of the quartz tube 8 is 20 mm, and the inner diameter of the pipe a 5 is 5 mm. One end of the pipe a5 is arranged at the center position of the top of the atomized particle generating device 4, and the other end is arranged at the center position of the bottom of the reaction chamber 6; the pipe a5 is perpendicular to the reaction chamber 6; the material of the pipe a5 is 304 stainless steel.

[0029] The atomized particle generating device 4 includes an ultrasonic transducer and a precursor solution storage chamber. The ultrasonic vibrator of the ultrasonic transducer generates ultrasonic waves and acts on the precursor solution to turn it into a mist. The precursor solution storage chamber is located above the ultrasonic transducer and is a 100 mL plastic cup. A resistance wire is provided outside the reaction chamber 6 to achieve heating, and the resistance wire is connected to a temperature control device; The sapphire single crystal fiber 7 is placed in a quartz tube 8 at the bottom of the reaction chamber 6, and a clamp is used to hang the sapphire single crystal fiber 7 at the center of the quartz tube 8; the length of the quartz tube 8 is greater than the length of the sapphire single crystal fiber 7.

[0030] Example 2 A method for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure, using the apparatus described in Example 1, comprises the following steps: Aluminum acetylacetonate and magnesium acetylacetonate were added to water to obtain a precursor solution, wherein the concentration of aluminum acetylacetonate and magnesium acetylacetonate in the precursor solution was 0.02 mol / L and 0.02 mol / L, respectively. A sapphire single crystal optical fiber (400 μm in diameter and 10 cm in length) was ultrasonically cleaned in methanol for 10 minutes, then ultrasonically cleaned in deionized water for 10 minutes, and finally, water droplets on the surface of the optical fiber were blown off with argon gas. After drying, the optical fiber was placed in the quartz tube 8 at the bottom of the reaction chamber 6, and a clamp was used to suspend the sapphire single crystal optical fiber in the center of the quartz tube 8 for use.

[0031] The prepared precursor solution is placed in the precursor solution storage chamber of the atomized particle generating device 4. The frequency of the ultrasonic transducer is 1.7 MHz, and the solution is converted into a large number of atomized droplets. The argon gas in the carrier bottle 1 is passed into the atomized particle generating device 4 through the carrier gas control device 3. The argon gas flow rate is 3L / min, so that the atomized droplets are pushed into the quartz tube 8 of the reaction chamber 6 for cladding growth.

[0032] The atomized droplets enter the quartz tube 8 under the push of argon gas, and are deposited on the sapphire optical fiber at a heating temperature of 450°C. The exhaust gas is then discharged through the exhaust port 9 and the exhaust device 10. The reaction time is 60 minutes.

[0033] The SEM image of the sapphire single crystal optical fiber with cladding obtained in this embodiment is shown in FIG. Figure 2 As shown by Figure 2 It can be seen that there is a clear interface between the sapphire fiber and the cladding, and the cladding thickness is about 7 microns.

[0034] After coating, the present invention can clad the sapphire optical fiber at a low cost, which will reduce light loss and improve the light transmission efficiency of the sapphire optical fiber. According to tests, the transmission loss of a sapphire optical fiber with a diameter of 400 μm before cladding is 1.03 dB / m, and the transmission loss of the sapphire optical fiber after cladding is 0.36 dB / m.

[0035] Example 3 A method for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure is as described in Example 2, except that the reaction temperature is 500°C.

[0036] Example 4 A method for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure is as described in Example 2, except that the argon gas flow rate is 2 L / min and the reaction temperature is 500°C.

[0037] Example 5 A method for growing a sapphire single crystal optical fiber cladding using vertical Mist-CVD is as described in Example 2, except that the concentration of aluminum acetylacetonate and magnesium acetylacetonate in the precursor solution is 0.05 mol / L, and the reaction temperature is 600°C.

[0038] Example 6 A method for growing a sapphire single crystal optical fiber cladding using vertical Mist-CVD is as described in Example 2, except that the concentration of aluminum acetylacetonate in the precursor solution is 0.04 mol / L, the concentration of magnesium acetylacetonate is 0.03 mol / L, the argon gas flow rate is 2 L / min, and the reaction temperature is 600°C.

[0039] The present invention aims to propose a new device and method for growing the cladding of a single-crystal optical fiber. Those skilled in the art may modify some of the technical features of the present invention without departing from the essential spirit of the technical solution of the present invention. Such modifications should be included within the scope of the technical solution for which protection is sought.

Claims

1. A device for growing sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure, characterized in that: The device includes an atomized particle generating device, a reaction chamber, a carrier gas control device, a carrier gas bottle and an exhaust device; A quartz tube is provided at the bottom center of the reaction chamber. The quartz tube is arranged vertically. The atomized particle generating device and the reaction chamber are arranged in a vertical structure. The top of the atomized particle generating device is connected to the lower end of the quartz tube via a pipe a. The atomized particle generating device is also connected to the carrier gas bottle via a pipe b. The pipe b is provided with a carrier gas control device. The reaction chamber is connected to an exhaust device through an exhaust port.

2. The device for growing a sapphire single crystal optical fiber cladding using vertical Mist-CVD according to claim 1, characterized in that: The quartz tube is open at both ends, and the inner diameter of the quartz tube is larger than the diameter of the sapphire single crystal optical fiber and not smaller than the inner diameter of the pipe a; the sapphire single crystal optical fiber is suspended at the center of the quartz tube using a clamp.

3. The device for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure according to claim 1, characterized in that: One end of the pipe a is arranged at the center position of the top of the atomized particle generating device, and the other end is arranged at the center position of the bottom of the reaction chamber; the pipe a is perpendicular to the reaction chamber.

4. The apparatus for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure according to claim 1, characterized in that: The atomized particle generating device includes an ultrasonic transducer and a precursor solution storage chamber, wherein the precursor solution storage chamber is located above the ultrasonic transducer; the material of the precursor solution storage chamber is plastic, corrosion-resistant steel or glass.

5. The apparatus for growing a sapphire single crystal optical fiber cladding using vertical Mist-CVD according to claim 1, characterized in that: A resistance wire is arranged outside the reaction chamber to achieve heating, and the resistance wire is connected to a temperature control device; The exhaust port is arranged at the upper part of the reaction chamber.

6. A method for growing a sapphire single crystal optical fiber cladding using vertical Mist-CVD, employing the apparatus of claim 1, comprising the following steps: Aluminum acetylacetonate and magnesium acetylacetonate are added to methanol to obtain a precursor solution; the precursor solution is placed in a precursor solution storage chamber of an atomized particle generating device to atomize the precursor solution into atomized droplets; carrier gas in a carrier gas tank is introduced into the atomized particle generating device through a carrier gas control device, so that the atomized droplets are pushed into a reaction chamber where a sapphire single crystal optical fiber is placed to react and obtain a cladding on the surface of the sapphire single crystal optical fiber; and finally, exhaust gas is discharged from an exhaust port through an exhaust device.

7. The method for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure according to claim 6, characterized in that: The concentration of aluminum acetylacetonate in the precursor solution is 0.02-0.06 mol / L, and the concentration of magnesium acetylacetonate is 0.02-0.06 mol / L.

8. The method for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure according to claim 6, characterized in that: The frequency of the ultrasonic transducer in the atomized particle generation device is 1.7-3 MHz; The carrier gas is argon, and the flow rate of the carrier gas is 2L / min-3L / min.

9. The method for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure according to claim 6, characterized in that: The sapphire single-crystal optical fiber is pretreated before being placed in the reaction chamber. The specific steps are as follows: the sapphire single-crystal optical fiber is ultrasonically cleaned in methanol for 10 minutes, then ultrasonically cleaned in deionized water for 10 minutes, and finally, water droplets on the surface of the optical fiber are blown off with argon gas. After drying, it is placed in the reaction chamber for use. The diameter of the sapphire single-crystal optical fiber is 300-400 μm and the length is 10-20 cm.

10. The method for growing a sapphire single crystal optical fiber cladding using Mist-CVD with a vertical structure according to claim 6, characterized in that The reaction temperature is 400-600° C., and the reaction time is 60-90 minutes.

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