Deposition layer preparation method of multiple refractive indexes, deposition tube and optical fiber preparation method

Abstract

The present application relates to the technical field of special optical fiber preparation process, and discloses a deposition layer preparation method with multiple refractive indexes, a deposition tube and an optical fiber preparation method. The deposition tube is used to implement the deposition layer preparation method with multiple refractive indexes. First, a suitable liner tube specification and a partitioning piece arranged in the liner tube are selected to divide the liner tube into multiple fan-shaped areas. At least one fan-shaped area is reserved, and a blocking piece blocks the remaining fan-shaped areas to assist the deposition of the unblocked fan-shaped areas. At least two deposition reactants are used to repeat the deposition multiple times until the deposition of all the fan-shaped areas is completed, and a deposition layer with multiple refractive indexes is formed. The process is simple and the operation is convenient. The optical fiber preparation method uses the deposition tube to prepare the deposition layer, and then fuses and shrinks the deposition tube to obtain an optical fiber preform. Then, the optical fiber preform is assembled and drawn to form an optical fiber. The optical fiber preparation method can directly fuse and shrink into an optical fiber preform with multiple refractive index distributions after deposition, the preparation process is simple, and better optical performance can be obtained.

Description

Technical Field

[0001] This invention relates to the field of special optical fiber fabrication technology, and in particular to a method for preparing a deposition layer with multiple refractive indices, a deposition tube, and an optical fiber fabrication method. Background Technology

[0002] With the continuous development of specialty optical fibers, non-circular symmetric refractive index distribution fibers, such as polarization-maintaining fibers, square fibers, photonic crystal fibers, and yttrium-doped laser fibers, are frequently used to achieve the desired optical performance. The manufacturing processes for these non-circular symmetric refractive index distribution fibers are diverse, often employing mechanical processing or assembly-collapse methods to prepare the required fiber preforms. For example, the preparation of panda-shaped polarization-maintaining fiber preforms uses a mechanical processing method, with main steps including: fabricating the mother rod, drilling, assembly, and drawing. This process requires precise drilling of the mother rod, followed by assembly and insertion of stress bars, and finally drawing into the optical fiber. As another example, the preparation of porous photonic crystal fibers uses an assembly-collapse method, first bundling capillaries into a liner tube, then melting and condensing them into a solid rod, and finally drawing into the optical fiber.

[0003] Current processes for fabricating special optical fibers are complex and cannot effectively control the distribution of multiple refractive indices to achieve higher stress levels. Therefore, there is an urgent need for a method for preparing deposition layers with multiple refractive indices, as well as a method for fabricating deposition tubes and optical fibers, to solve these technical problems. Summary of the Invention

[0004] The first objective of this invention is to provide a method for preparing deposition layers with multiple refractive indices, which can prepare deposition layers with different refractive index distributions and has a simple process.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] Methods for preparing deposition layers with various refractive indices include:

[0007] The specifications of the liner are selected according to the deposition process, and the spacer is selected according to the specifications of the liner; the spacer is installed with the liner, and the spacer divides the internal space of the liner into multiple sector regions;

[0008] Reserve at least one of the fan-shaped areas that has not been deposited, and seal off the remaining fan-shaped areas;

[0009] The liner is installed in the deposition bed to deposit material in the unsealed fan-shaped area;

[0010] Remove the liner from the deposition bed and unblock the remaining fan-shaped area;

[0011] The aforementioned operation is repeated multiple times for deposition, using at least two deposition reactants, until all of the multiple fan-shaped regions have been deposited, forming a deposition layer with multiple refractive indices.

[0012] As a preferred technical solution for preparing deposition layers with multiple refractive indices, adjacent fan-shaped regions are deposited using different deposition reactants.

[0013] The second objective of this invention is to provide a deposition tube that assists in the preparation of deposition layers and can also serve as a base material for optical fibers with non-circular symmetric refractive index distributions.

[0014] To achieve this objective, the present invention adopts the following technical solution:

[0015] A deposition tube for implementing the deposition layer preparation method with multiple refractive indices as described above, the deposition tube comprising the liner, the spacer and the sealing member, the spacer being disposed inside the liner and the sealing member being used to selectively seal a portion of the fan-shaped region.

[0016] As a preferred technical solution for the deposition tube, the isolation element includes a spatial isolation element and a deposition layer isolation element, the deposition layer isolation element is connected to the liner tube, and the spatial isolation element is detachably disposed on the deposition layer isolation element.

[0017] As a preferred technical solution for the deposition tube, the length of the deposition layer isolation member is the same as the length of the liner; the outer wall of the deposition layer isolation member is connected to the inner wall of the liner, and the curvature of the outer wall of the deposition layer isolation member is the same as the curvature of the inner wall of the liner.

[0018] As a preferred technical solution for the deposition tube, the thickness of the deposition layer isolation element is the same as the thickness of the deposition layer.

[0019] As a preferred technical solution for the deposition tube, the length of the space isolation member is the same as the length of the liner; the outer wall of the space isolation member is connected to the inner wall of the deposition layer isolation member, and the curvature of the outer wall of the space isolation member is the same as the curvature of the inner wall of the deposition layer isolation member; the thickness of the space isolation member is the difference between the inner diameter of the liner and the thickness of the deposition layer isolation member.

[0020] As a preferred technical solution for the deposition tube, multiple spatial isolation elements and multiple deposition layer isolation elements are provided, with each of the multiple spatial isolation elements corresponding to one of the multiple deposition layer isolation elements, and the ends of the multiple spatial isolation elements away from the deposition layer isolation elements are arranged crosswise at the axial position of the liner tube.

[0021] As a preferred technical solution for the deposition tube, the deposition tube includes a snap-fit ​​component disposed at one end of the liner tube. The liner tube and the snap-fit ​​component form a plurality of fan-shaped holes, and the fan-shaped holes are connected to the fan-shaped regions one by one. The space isolation component and the deposition layer isolation component are both snapped into the snap-fit ​​component, and the sealing component can selectively seal the fan-shaped holes.

[0022] The third objective of this invention is to provide a method for preparing optical fibers, which can yield optical fibers with better optical performance and has a simple preparation process.

[0023] To achieve this objective, the present invention adopts the following technical solution:

[0024] The optical fiber fabrication method, wherein the deposition layer is prepared using a deposition tube as described in any of the preceding claims, further comprises:

[0025] The deposition tube after the deposition layer has been prepared is subjected to melt polycondensation to obtain an optical fiber preform;

[0026] The optical fiber preform is assembled in a high-temperature drawing furnace and drawn into optical fibers to form the optical fiber.

[0027] The beneficial effects of this invention are:

[0028] The present invention provides a method for preparing a deposition layer with multiple refractive indices. The method includes: first, selecting a suitable liner specification based on the deposition process; then, selecting a suitable spacer based on the liner specification; installing the spacer onto the liner, which divides the internal space of the liner into multiple independent fan-shaped regions; reserving at least one fan-shaped region, sealing the remaining fan-shaped regions; installing the liner on the deposition bed; depositing on the unsealed fan-shaped regions; forming a partial deposition layer in these fan-shaped regions; removing the liner from the deposition bed and unsealing; continuing to select reserved areas in the fan-shaped regions that have not yet been deposited, and repeating the above operation multiple times, using at least two deposition reactants to form a deposition layer with multiple refractive indices, until all multiple fan-shaped regions have been deposited, and the deposition layer preparation is complete. The present invention mainly adopts an in-tube isolation deposition method, involving multiple depositions, with a simple process and convenient operation.

[0029] The deposition tube provided by this invention is used to implement the above-described method for preparing deposition layers with multiple refractive indices. The deposition tube includes a liner, a separator, and a sealing element. The separator is disposed inside the liner and is used to separate the liner so that multiple depositions can be performed to increase the number of refractive indices. The sealing element is used to selectively seal a portion of the fan-shaped region to assist in the preparation of the deposition layer. The deposition tube can also serve as a base material for optical fibers with non-circular symmetric refractive index distributions.

[0030] The optical fiber fabrication method provided by this invention uses a sleeve method and a deposition tube as described above to prepare a deposition layer. The optical fiber fabrication method further includes: melting and polycondensing the deposition tube after the deposition layer has been prepared to obtain an optical fiber preform; then assembling the optical fiber preform in a high-temperature drawing furnace, heating and melting the head of the optical fiber preform, and drawing it into an optical fiber using equipment. Using this optical fiber fabrication method, an optical fiber preform with multiple refractive index distributions can be directly melted and condensed after deposition. The fabrication process is simple and can also enable the optical fiber to obtain better optical performance. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the deposition tube provided in a specific embodiment of the present invention;

[0032] Figure 2 This is an exploded schematic diagram of the deposition tube provided in a specific embodiment of the present invention;

[0033] Figure 3 This is a cross-sectional view of a deposition tube with the space isolation component not removed, provided in a specific embodiment of the present invention;

[0034] Figure 4 This is a cross-sectional view of the deposition tube with the space isolation component removed, provided in a specific embodiment of the present invention;

[0035] Figure 5 This is a cross-sectional view of the optical fiber preform provided in Embodiment 1 of the present invention.

[0036] Figure 6 This is a schematic diagram of the refractive index distribution of an optical fiber preform provided in Embodiment 1 of the present invention.

[0037] Figure 7 This is a cross-sectional view of the optical fiber preform provided in Embodiment 2 of the present invention;

[0038] Figure 8 This is a cross-sectional view of the optical fiber preform provided in Embodiment 3 of the present invention.

[0039] In the picture:

[0040] 1. Deposition tube; 10. Liner; 11. Isolator; 111. Deposition layer isolation component; 112. Space isolation component; 12. Deposition layer; 13. Clip-on component; 14. Sealing component. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0042] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0044] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0045] Specifically, such as Figures 1 to 4As shown, in a first aspect, the present invention discloses a method for preparing a deposition layer 12 with multiple refractive indices. The method includes: firstly, selecting a suitable liner 10 specification according to the deposition process; then, selecting a suitable spacer 11 according to the liner 10 specification; installing the spacer 11 onto the liner 10, which divides the internal space of the liner 10 into multiple independent fan-shaped regions; reserving at least one fan-shaped region, sealing the remaining fan-shaped regions; installing the liner 10 on a deposition bed; depositing on the unsealed fan-shaped regions; forming a partial deposition layer 12 within these fan-shaped regions; removing the liner 10 from the deposition bed and unsealing; continuing to select reserved areas in the fan-shaped regions that have not yet been deposited; repeating the above operation multiple times, using at least two deposition reactants to form a deposition layer 12 with multiple refractive indices, until all multiple fan-shaped regions have been deposited, and the deposition layer 12 is completed. The present invention mainly adopts an in-tube isolation deposition method, involving multiple depositions, with a simple process and convenient operation.

[0046] Specifically, multiple sector regions have equal cross-sectional areas and are mutually enclosed and independent. For example, adjacent sector regions can be deposited using different deposition reactants according to the desired refractive index distribution.

[0047] Secondly, the present invention discloses a deposition tube 1 for implementing the above-described method for preparing a deposition layer 12 with multiple refractive indices. The deposition tube 1 includes a liner 10, an isolator 11, and a sealing member 14. The isolator 11 is disposed inside the liner 10 and is used to separate the liner 10 so that multiple depositions can be performed to increase the number of refractive indices. The sealing member 14 is used to selectively seal a portion of the fan-shaped region to assist in the segmented preparation of the deposition layer 12. The deposition tube 1 can also serve as a base material for optical fibers with non-circular symmetric refractive index distributions.

[0048] Preferably, the spacer 11 includes a spatial spacer 112 and a deposition layer spacer 111. The deposition layer spacer 111 is connected to the liner 10. The spatial spacer 112 is detachably disposed on the deposition layer spacer 111. The deposition layer spacer 111 remains in the liner 10 to participate in subsequent melt polycondensation and serves as a spacer between different refractive indices of the deposition layer 12.

[0049] Specifically, the length of the deposition layer spacer 111 is the same as the length of the liner 10; the outer wall of the deposition layer spacer 111 is connected to the inner wall of the liner 10, the cross-section of the deposition layer spacer 111 is arc-shaped, and the curvature of the outer wall of the deposition layer spacer 111 is the same as the curvature of the inner wall of the liner 10. For example, the length of the liner 10 can be 0.5 meters to 2 meters, and the material of the liner 10 is generally quartz glass, while the deposition layer spacer 111 should be made of high-purity quartz with a hydroxyl content of less than 20 ppm for better results.

[0050] Optionally, the effect is best when the thickness of the deposited layer separator 111 is the same as the thickness of the deposited layer 12, and the thickness of the deposited layer 12 is preferably 0.1 mm to 20 mm.

[0051] Furthermore, the length of the spacer 112 is the same as the length of the liner 10; the outer wall of the spacer 112 is connected to the inner wall of the deposition layer spacer 111, and the curvature of the outer wall of the spacer 112 is the same as the curvature of the inner wall of the deposition layer spacer 111; the thickness of the spacer 112 is the difference between the inner diameter of the liner 10 and the thickness of the deposition layer spacer 111.

[0052] In this embodiment, multiple space isolation members 112 are provided, and multiple deposition layer isolation members 111 are also provided. The multiple space isolation members 112 and the multiple deposition layer isolation members 111 are provided in a one-to-one correspondence. The ends of the multiple space isolation members 112 away from the deposition layer isolation members 111 are arranged crosswise at the axial position of the liner tube 10, which can effectively divide the internal space of the liner tube 10 evenly.

[0053] Preferably, the deposition tube 1 includes a snap-fit ​​member 13, which is disposed at one end of the liner 10. The liner 10 and the snap-fit ​​member 13 form a plurality of fan-shaped holes, and the fan-shaped holes are connected to the fan-shaped areas one by one. The space isolation member 112 and the deposition layer isolation member 111 are both snapped and fixed with the snap-fit ​​member 13. The sealing member 14 can selectively seal the fan-shaped holes to achieve the purpose of sealing the fan-shaped areas. For example, the snap-fit ​​member 13 can be provided at both ends of the liner 10, which can better fix the deposition layer isolation member 111 and the space isolation member 112. Correspondingly, the sealing member 14 is set as a fan shape, and multiple sealing members 14 are also provided at both ends of the liner 10, which can correspond one-to-one with the fan-shaped holes. The sealing member 14 is made of polytetrafluoroethylene, which has the characteristics of heat resistance, cold resistance, corrosion resistance, good toughness, high lubricity, and low coefficient of friction. The snap-fit ​​member 13 is also made of polytetrafluoroethylene.

[0054] Thirdly, this invention discloses an optical fiber fabrication method, which uses a sleeve method and a deposition tube 1 as described above to prepare a deposition layer 12. The optical fiber fabrication method further includes: melting and polycondensing the deposition tube 1 after the deposition layer 12 is prepared to obtain an optical fiber preform; then assembling the optical fiber preform in a high-temperature drawing furnace, heating and melting the head of the optical fiber preform, and drawing it into an optical fiber using equipment. Using this optical fiber fabrication method, an optical fiber preform with multiple refractive index distributions can be directly melted and condensed after deposition. The fabrication process is simple, and the optical fiber can obtain better optical performance and higher stress.

[0055] In the deposition tube 1 after the deposition layer 12 is prepared, the space isolation component 112 can be removed first, while the deposition layer isolation component 111 is retained and not removed, serving as an isolation layer with different refractive indices. Then, melt polycondensation is performed, and optical fiber preforms with non-circular symmetric refractive index distributions are directly prepared by multiple depositions and one melt polycondensation, which can produce optical fibers with better performance.

[0056] Example 1:

[0057] Step 1: Select either PCVD (Plasma Chemical Vapor Deposition) or MCVD (Modified Chemical Vapor Deposition) process, and design as follows: Figure 5 and Figure 6 The deposition parameters of the optical fiber preform shown are generally reactants such as silicon (Si), germanium (Ge), fluorine (F), and oxygen (O), and the corresponding specifications and sizes of the liner 10 are selected simultaneously.

[0058] Step 2: Select the appropriate size of the separator 11, snap-fit ​​component 13, and sealing component 14 according to the specifications of the liner 10, and assemble them with the liner 10 to form a deposition tube 1 with four independent fan-shaped spaces, such as... Figure 1 As shown, two sealing components 14 are used to block two of the fan-shaped areas respectively;

[0059] Step 3: Install the liner 10 onto the deposition bed and perform the first deposition on the two unsealed fan-shaped areas;

[0060] Step 4: After deposition is completed, remove the liner 10 from the deposition bed, remove the two sealing parts 14, and use them to block the two fan-shaped areas that have already been deposited. Then, reinstall the liner 10 onto the deposition bed and perform a second deposition on the remaining two unsealed and undeposited fan-shaped areas to form a deposition layer 12 with two refractive indices.

[0061] Step 5: Remove the sealing component 14 and the snap-fit ​​component 13 in sequence, and then remove the four space isolation components 112.

[0062] Step 6: After melt polycondensation of the liner 10 with the deposited layer 12, an optical fiber preform is obtained. The cross-section of the optical fiber preform is shown in the figure. Figure 5 As shown in the figure, the distributions of its two refractive indices n1 and n2 are as follows: Figure 6 As shown, n1 and n2 can actually be either a gradient refractive index distribution or a step-index refractive index distribution;

[0063] Step 7: Assemble the optical fiber preform in a high-temperature drawing furnace and heat and draw the head to form an optical fiber.

[0064] Example 2:

[0065] Step 1: Select either PCVD (Plasma Chemical Vapor Deposition) or MCVD (Modified Chemical Vapor Deposition) process, and design as follows: Figure 7 The deposition parameters of the optical fiber preform shown are generally reactants such as silicon (Si), germanium (Ge), fluorine (F), and oxygen (O), and the corresponding specifications and sizes of the liner 10 are selected simultaneously.

[0066] Step 2: Select the appropriate size of the isolation component 11, snap-fit ​​component 13 and sealing component 14 according to the specifications of the liner 10, and assemble them with the liner 10 to form a deposition tube 1 with 4 independent fan-shaped spaces. Use three sealing components 14 to block three of the fan-shaped areas respectively.

[0067] Step 3: Install the liner 10 onto the deposition bed and perform the first deposition on an unsealed fan-shaped area;

[0068] Step 4: After deposition is completed, remove the liner 10 from the deposition bed, remove the three sealing parts 14, reserve one undeposited fan-shaped area again and block all the remaining three fan-shaped areas, reinstall the liner 10 onto the deposition bed, and perform a second deposition on the reserved undeposited and unblocked fan-shaped area. Reserve and deposit the undeposited fan-shaped areas in sequence.

[0069] Step 5: After four depositions, a deposition layer 12 with four refractive indices is formed. The sealing component 14 and the snap-fit ​​component 13 are removed in sequence, and then the four space isolation components 112 are removed.

[0070] Step 6: After melt polycondensation of the liner 10 with the deposited layer 12, an optical fiber preform is obtained. The cross-section of the optical fiber preform is shown in the figure. Figure 7 As shown in the figure, n1, n2, n3, and n4 can actually be either a gradient refractive index distribution or a step-index refractive index distribution;

[0071] Step 7: Assemble the optical fiber preform in a high-temperature drawing furnace and heat and draw the head to form an optical fiber.

[0072] Example 3:

[0073] Step 1: Select either PCVD (Plasma Chemical Vapor Deposition) or MCVD (Modified Chemical Vapor Deposition) process, and design as follows: Figure 8 The deposition parameters of the optical fiber preform shown are generally reactants such as silicon (Si), germanium (Ge), fluorine (F), and oxygen (O), and the corresponding specifications and sizes of the liner 10 are selected simultaneously.

[0074] Step 2: Select the appropriate size of the isolation component 11, snap-fit ​​component 13 and sealing component 14 according to the specifications of the liner 10, and assemble them with the liner 10 to form a deposition tube 1 with 3 independent fan-shaped spaces. Use two sealing components 14 to block two of the fan-shaped areas respectively.

[0075] Step 3: Install the liner 10 onto the deposition bed and perform the first deposition on an unsealed fan-shaped area;

[0076] Step 4: After deposition is completed, remove the liner 10 from the deposition bed, remove the two sealing parts 14, reserve one undeposited fan-shaped area again and block the other two fan-shaped areas, reinstall the liner 10 onto the deposition bed, and perform a second deposition on the reserved undeposited and unblocked fan-shaped area. Reserve and deposit the undeposited fan-shaped areas in sequence.

[0077] Step 5: After three depositions, a deposition layer 12 with three refractive indices is formed. The sealing component 14 and the snap-fit ​​component 13 are removed in sequence, and then the three space isolation components 112 are removed.

[0078] Step 6: After melt polycondensation of the liner 10 with the deposited layer 12, an optical fiber preform is obtained. The cross-section of the optical fiber preform is shown in the figure. Figure 8 As shown in the figure, n1, n2, and n3 can actually be either a gradient refractive index distribution or a step-index refractive index distribution;

[0079] Step 7: Assemble the optical fiber preform in a high-temperature drawing furnace and heat and draw the head to form an optical fiber.

[0080] Specifically, PCVD is a preform manufacturing method that uses microwave plasma to oxidize and deposit gas inside a quartz tube; while MCVD is a method that uses high-purity useful gas, with oxygen as a carrier, to obtain solid-phase deposits through a high-temperature vapor-phase oxidation reaction inside a rotating quartz tube. MCVD can produce low-loss optical fibers and can easily change the refractive index distribution of the fiber to create optical fibers with various structures. PCVD has a higher electron temperature of the reacting gas, resulting in a more complete reaction and higher deposition efficiency than MCVD. The deposition temperature is also lower than that of MCVD, making the deposition tube 1 less prone to deformation. The resulting deposition layer 12 has good longitudinal uniformity, and with precise microcomputer-controlled processes, it is possible to create a large number of deposition layers 12 with very thin thicknesses for each layer, although the cost is slightly higher. The choice can be made based on actual performance requirements.

[0081] Understandably, melt polycondensation is a commonly used polymerization method. Melt polycondensation is an exothermic reaction, and to avoid prolonged high-temperature oxidation, the entire process must be carried out under reduced pressure and nitrogen protection. To further accelerate optical fiber fabrication, a high-temperature drawing furnace and a melt polycondensation furnace can be appropriately combined. Because the polycondensation reaction occurs above the melting temperature of the monomer and polymer, the optical fiber preform remains in a molten state after the polycondensation reaction, allowing for direct drawing. This reduces energy consumption, shortens the processing time, and improves production efficiency. Melt polycondensation does not require solvents, thus minimizing the introduction of impurities and ensuring optical fiber quality.

[0082] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a deposition layer with multiple refractive indices, characterized in that, include: The specifications of the liner (10) are selected according to the deposition process, and the separator (11) is selected according to the specifications of the liner (10); the separator (11) is installed with the liner (10), and the separator (11) divides the internal space of the liner (10) into multiple fan-shaped areas; Reserve at least one of the fan-shaped areas that has not been deposited, and seal off the remaining fan-shaped areas; The liner (10) is installed in the deposition bed to deposit the unsealed fan-shaped area; Remove the liner (10) from the deposition bed and unblock the remaining fan-shaped area; The aforementioned operation is repeated multiple times for deposition, using at least two deposition reactants, until all of the multiple fan-shaped regions are deposited, forming a deposition layer with multiple refractive indices (12).

2. The method for preparing a deposition layer with multiple refractive indices according to claim 1, characterized in that, Adjacent sector regions are deposited using different deposition reactants.

3. A deposition tube, characterized in that, For implementing the deposition layer preparation method with multiple refractive indices as described in claim 1, the deposition tube includes the liner (10), the spacer (11) and the plug (14), the spacer (11) being disposed inside the liner (10), and the plug (14) being used to selectively plug part of the fan-shaped region; The isolation element (11) includes a space isolation element (112) and a deposition layer isolation element (111), the deposition layer isolation element (111) is connected to the liner (10), and the space isolation element (112) is detachably disposed on the deposition layer isolation element (111).

4. The deposition tube according to claim 3, characterized in that, The length of the deposition layer isolation element (111) is the same as the length of the liner (10); the outer wall of the deposition layer isolation element (111) is connected to the inner wall of the liner (10), and the curvature of the outer wall of the deposition layer isolation element (111) is the same as the curvature of the inner wall of the liner (10).

5. The deposition tube according to claim 3, characterized in that, The thickness of the deposition layer separator (111) is the same as the thickness of the deposition layer (12).

6. The deposition tube according to claim 3, characterized in that, The length of the space isolation element (112) is the same as the length of the liner (10); the outer wall of the space isolation element (112) is connected to the inner wall of the deposition layer isolation element (111), and the curvature of the outer wall of the space isolation element (112) is the same as the curvature of the inner wall of the deposition layer isolation element (111); the thickness of the space isolation element (112) is the difference between the inner diameter of the liner (10) and the thickness of the deposition layer isolation element (111).

7. The deposition tube according to claim 3, characterized in that, Multiple space isolation elements (112) are provided, and multiple deposition layer isolation elements (111) are provided. The multiple space isolation elements (112) and the multiple deposition layer isolation elements (111) are provided in a one-to-one correspondence. The ends of the multiple space isolation elements (112) away from the deposition layer isolation elements (111) are arranged crosswise at the axial position of the liner (10).

8. The deposition tube according to any one of claims 3-7, characterized in that, The deposition tube includes a snap-fit ​​member (13), which is disposed at one end of the liner (10). The liner (10) and the snap-fit ​​member (13) form a plurality of fan-shaped holes. The fan-shaped holes are connected to the fan-shaped areas one by one. The space isolation member (112) and the deposition layer isolation member (111) are both snapped with the snap-fit ​​member (13). The sealing member (14) can selectively seal the fan-shaped holes.

9. A method for fabricating optical fibers, characterized in that, The deposition layer (12) is prepared using the deposition tube (1) as described in claim 3, and the optical fiber preparation method further includes: The deposition tube (1) after the deposition layer (12) has been prepared is subjected to melt polycondensation to obtain an optical fiber preform; The optical fiber preform is assembled in a high-temperature drawing furnace and drawn into optical fibers to form the optical fiber.

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