An apparatus and method for fabricating attenuated fiber preforms using the VAD method.

Abstract

This invention discloses an apparatus and method for preparing attenuated optical fiber preforms using the VAD method. Through segmented impregnation and sintering, the fiber core of the preform is longitudinally divided into multiple segments with different attenuation values ​​in different segments. Furthermore, the fiber core within each segment has the same attenuation value. This method maintains high consistency in the process of preparing multi-segment attenuated optical fiber preforms, avoiding process deviations caused by multiple preform preparations. It provides an effective method for preparing attenuated optical fibers with various attenuation types, greatly improving research and production efficiency and reducing research and production time and costs.

Description

Technical Field

[0001] This invention relates to the field of optical fiber fabrication technology, and in particular to an apparatus and method for fabricating attenuated optical fiber preforms using the VAD method. Background Technology

[0002] To meet the requirements of long-distance transmission, fiber optic amplifiers are often used in optical communication systems to increase transmission power and distance. However, on the other hand, high optical power may exceed the detection range of photodetectors. Therefore, passive attenuators are needed to reduce the signal power to a suitable range to avoid distortion caused by excessively high optical power. Fiber optic attenuators, as passive optical devices, are used in optical communication systems to adjust optical power performance, calibrate fiber optic instruments, and attenuate fiber optic signals. Fiber optic attenuator testing systems are widely used due to their high attenuation accuracy, low additional loss, and good stability. However, in practical applications, fiber optic attenuators with different attenuation values ​​are required due to the different distances between base stations and receivers. Therefore, there is a need for attenuated fibers with different attenuation values.

[0003] In practical applications, fiber optic attenuators can be categorized by port type, such as SC series and LC series. Correspondingly, there are also SC series and LC series fibers, each ranging from 1 to 30 dB. The attenuation value per unit length varies for each fiber type. For example, SC fibers are typically 21.0 cm long, meaning SC-1dB has a loss of 1 dB for a 21.0 mm fiber, with a typical attenuation requirement of 0.286 dB per centimeter. LC fibers, on the other hand, are typically 15.4 m long, meaning LC-1dB has a loss of 1 dB for a 15.4 mm fiber, with a typical attenuation requirement of 0.422 dB per centimeter. The table below shows typical attenuation values ​​required for some LC and SC series attenuation fibers on the market. It can be seen that there are numerous types of fiber core attenuation values ​​that need to be controlled, greatly increasing the difficulty of production and manufacturing.

[0004]

[0005]

[0006] However, in the actual fabrication of existing attenuated optical fibers, it is difficult to maintain consistency in the fabrication process of optical fiber preforms for such a variety of types with different attenuation values. This results in a lack of a good linear correspondence between the attenuation value and the doping concentration of different attenuated optical fibers. When fabricating attenuated optical fibers with the required target attenuation value, it is easy for the fiber attenuation value to deviate, which cannot accurately achieve the required attenuation value of the product. This leads to an extremely high scrap rate, requiring multiple fabrications to achieve the desired result, which greatly increases the research and development and production costs. Summary of the Invention

[0007] The purpose of this invention is to provide an apparatus and method for preparing attenuated fiber preforms using the VAD method to solve the above-mentioned problems. This invention can simultaneously prepare attenuated fiber preforms with multiple attenuation values, which can greatly reduce the cost and time of research and development and production. At the same time, since the multiple attenuation values ​​of the preform are essentially from the same preform, the preparation process is highly consistent, and it is easier to obtain a regular relationship between fiber attenuation value and metal ion doping concentration, which is beneficial to the optimization of attenuated fiber technology.

[0008] The present invention achieves the above objectives through the following technical solutions:

[0009] An apparatus for preparing attenuated optical fiber preforms by the VAD method, comprising a doping apparatus and a sintering apparatus;

[0010] The doping device includes several solution tanks, which are connected to a solution pump via pipes. The solution pump is connected to a solution spray head via pipes. Each solution spray head has isolation components on both sides. The solution spray head is fixed on a guide rail, which is used to drive the solution spray head to move back and forth within the length of the isolation components on both sides.

[0011] A horizontal lathe is provided below the solution spray head;

[0012] The sintering apparatus includes a sintering furnace, and the sintering furnace is equipped with a heating device.

[0013] A further option is to fix the isolation component in place.

[0014] A further embodiment is that the horizontal lathe is used to clamp and rotate the optical fiber preform at a speed of 0-20 rpm, so that the solution sprayed from the solution spray head fully wets the optical fiber preform; the guide rail moves at a speed of 10-200 mm / min.

[0015] A further embodiment is that the sintering device is used to sinter the impregnated optical fiber preform.

[0016] Another aspect of the present invention provides a method for preparing attenuated fiber preforms using the VAD method, comprising the following steps:

[0017] Step 1: Prepare optical fiber preforms using the VAD method. The optical fiber preforms include a seed rod and a loose core layer covering the outside of the seed rod.

[0018] Step 2: Prepare aqueous solutions of chlorides with different concentrations of decaying ions, and inject the aqueous solutions of different concentrations into different solution tanks of the doping device from left to right in order of increasing decaying ion concentration.

[0019] Step 3: Install the prepared optical fiber preform onto the horizontal lathe of the doping device, start the doping device, and the solution spray head sprays the solution connected to each other onto the core loose layer. At the same time, each solution spray head only moves back and forth within the set stroke area within the length of the isolation parts on both sides until all core loose layers are completely wetted, and a longitudinally segmented core loose layer is obtained; then dry it on the horizontal lathe for 1-2 hours until there is no solution flow or dripping in the core loose layer.

[0020] Step 4: Place the dried optical fiber preform into the sintering device. First, purge the cavity of the sintering device with nitrogen or an inert gas to replace the atmosphere. Then, purge with chlorine, helium, and nitrogen at 200℃-400℃ to dehydrate the loose core layer. Next, purge with oxygen and helium at 1000-1300℃ to oxidize the attenuating chloride ions in the loose core layer. Finally, continue to raise the temperature to 1800-2100℃ to sinter the loose core layer until it is transparent, thus obtaining a transparent core optical fiber preform.

[0021] Step 5: Using the transparent core fiber preform as a seed rod, deposit a cladding porous body on its surface using the VAD method to obtain a quartz cladding porous body fiber preform.

[0022] Step 6: Place the quartz clad loose fiber preform into the sintering apparatus. First, purge the cavity of the sintering apparatus with nitrogen or an inert gas to replace the atmosphere. Then, purge the loose clad with chlorine, helium, or nitrogen at 200℃-400℃ to dehydrate the loose clad. After that, raise the temperature to 1800-2200℃ and sinter the loose clad until it is transparent, obtaining a transparent attenuation fiber preform with a core and cladding structure.

[0023] A further embodiment is that the core loose layer is a porous material of silicon dioxide and germanium dioxide, and is doped with fluorine and phosphorus elements. The diameter of the core loose layer is 10-30 mm and the length is 600-1500 mm.

[0024] A further embodiment is that the core layer porous layer component includes silicon dioxide, with a porous body diameter of 10-120 mm and a length of 600-1500 mm.

[0025] A further embodiment is that the aqueous solution containing the different concentrations of decaying ion chlorides includes CoCl2, aluminum chloride, and other co-doped decaying ion chlorides. The mass fraction of CoCl2 is 0.01%-0.75%, the mass fraction of aluminum chloride is 1.5%-3.0%, and the other co-doped decaying ion chlorides include one or more chlorides of Cr, Mn, Fe, Co, Ni, Cu, and Zn, each with a mass fraction of 0.01%-1.2%.

[0026] A further embodiment is that the attenuation fiber preform core obtained in step 6 has multiple segments with different attenuation values, and multiple segments of optical fiber with different attenuation specifications can be obtained by drawing.

[0027] The beneficial effects of this invention are as follows:

[0028] This invention discloses an apparatus and method for preparing attenuated optical fiber preforms using the VAD method. Through segmented impregnation and sintering, the fiber core of the preform is longitudinally divided into multiple segments with different attenuation values ​​in different segments. Furthermore, the fiber core within each segment has the same attenuation value. This method maintains high consistency in the process of preparing multi-segment attenuated optical fiber preforms, avoiding process deviations caused by multiple preform preparations. It provides an effective method for preparing attenuated optical fibers with various attenuation types, greatly improving research and production efficiency and reducing research and production time and costs. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The diagram shown is a schematic diagram of the loose body spraying and wetting process of the present invention;

[0031] Figure 2 The diagram shown is an overall schematic of the doping device of the present invention.

[0032] Figure 3 The diagram shows a schematic of VAD fabrication of a porous core layer.

[0033] Figure 4 The diagram shows the process of loose material entering the VAD sintering furnace.

[0034] Figure 5 The diagram shows a schematic of VAD preparation of a porous cladding body;

[0035] Figure 6 The figure shown is a longitudinal chromium ion concentration distribution diagram of the core of the attenuation fiber preform in the embodiment.

[0036] Figure 7 The figure shown is a longitudinal iron ion concentration distribution diagram of the core of the attenuated fiber preform in the embodiment.

[0037] Figure 8 The figure shown is a longitudinal cobalt ion concentration distribution diagram of the core of the attenuation fiber preform in the embodiment.

[0038] Figure 9The attenuation fiber loss spectrum after the fiber preform in section A is drawn into fibers;

[0039] Figure 10 The attenuation fiber loss spectrum after the fiber preform of section B is drawn into fibers;

[0040] Figure 11 The attenuation fiber loss spectrum after the C-segment fiber preform is drawn;

[0041] The following are the labels in the diagram: 1-Core loose layer, 2-Solution spray head, 3-Isolation component, 4-Deposition seed rod, 5-Solution pump, 6-Solution tank, 7-Guide rail, 8-Horizontal lathe, 9-VAD deposition torch, 10-Clad loose body, 11-Sintering furnace, 12-Heating device. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0043] Example 1

[0044] An apparatus for preparing attenuated optical fiber preforms by the VAD method according to the present invention includes a doping apparatus and a sintering apparatus.

[0045] The doping device includes several solution tanks 6, which are connected to a solution pump 5 via pipes. The solution pump 5 is connected to a solution spray head 2 via pipes. Each solution spray head 2 is provided with isolation components 3 on both sides. The solution spray head 2 is fixed on a guide rail 7, which is used to drive the solution spray head 2 to move back and forth within the length of the isolation components 3 on both sides.

[0046] A horizontal lathe 8 is provided below the solution spray head 2;

[0047] The sintering apparatus includes a sintering furnace 11, and the sintering furnace 11 is equipped with a heating device 12.

[0048] The isolation component 3 is fixedly installed.

[0049] The horizontal lathe 8 is used to clamp and rotate the optical fiber preform at a speed of 0-20 rpm, so that the solution sprayed from the solution spray head 2 can fully wet the optical fiber preform; the guide rail 7 moves at a speed of 10-200 mm / min.

[0050] The sintering apparatus is used to sinter the impregnated optical fiber preform.

[0051] Example 2

[0052] The present invention discloses a method for preparing attenuated optical fiber preforms using the VAD method, comprising the following steps:

[0053] First, a core porous layer is prepared using a VAD device. The core porous layer consists of fluorine-doped silicon dioxide and germanium dioxide. The core porous layer has a diameter of 25 mm and a length of 1.3 m.

[0054] Three solutions of different concentrations were prepared: Solution A: AlCl3 mass fraction: 2.657%, CrCl3 mass fraction: 0.005489%, FeCl3 mass fraction: 0.02249%, CoCl2 mass fraction: 0.04949%; Solution B: AlCl3 mass fraction: 2.657%, CrCl3 mass fraction: 0.1096%, FeCl3 mass fraction: 0.04492%, CoCl2 mass fraction: 0.09885%; Solution C: AlCl3 mass fraction: 2.657%, CrCl3 mass fraction: 0.01639%, FeCl3 mass fraction: 0.06719%, CoCl2 mass fraction: 0.01478%. These three solutions were injected sequentially into the three solution tanks 6 of the doping device of the present invention according to their concentration.

[0055] The solution spray head 2 of the doping device is set to move 400mm, the rotation speed of the horizontal lathe 8 is set to 12rpm, the doping device is started, the solution pump 5 is turned on, and the core layer is wetted with solution until the core layer is completely wetted.

[0056] After the core layer is initially dried in air on the lathe of the doping device until there is no solution dripping from the loose material, the doped optical fiber preform is taken out and installed into the sintering furnace 11. First, 15 slm of nitrogen is introduced to replace the cavity for 20 minutes, then 5 slm of helium, 10 slm of nitrogen, and 0.4 slm of chlorine are introduced to dehydrate and dry the core layer. The heating device 12 controls the temperature at 350℃ and the drying time is 2 hours. After it is completely dried, 5 slm of helium and 10 slm of oxygen are introduced, and the heating device 12 controls the temperature at 1300℃ to oxidize and remove chlorine from the metal ions in the core layer. Finally, 5 slm of helium and 10 slm of oxygen are introduced, and the heating furnace 12 controls the temperature at 1900℃ to sinter the core layer until it is transparent.

[0057] The prepared loose core layer is reinstalled into the VAD deposition cavity as a core rod, and a loose cladding body is deposited. The loose cladding body is composed of silicon dioxide, resulting in a quartz cladding loose optical fiber preform, achieving core-cladding ratio matching.

[0058] The deposited quartz cladding porous fiber preform is reinstalled into the sintering furnace 11. Nitrogen gas is first introduced at 25 slm for cavity replacement for 20 minutes, followed by helium gas at 10 slm, nitrogen gas at 15 slm, and chlorine gas at 0.4 slm to dehydrate and dry the porous cladding. The heating device 12 controls the temperature at 400℃ and the drying time is 2 hours. After complete drying, helium gas at 15 slm and oxygen gas at 10 slm are introduced, and the heating device 12 controls the temperature at 1900℃ to sinter the porous cladding until it becomes transparent, resulting in a transparent attenuation fiber preform with three different attenuation values.

[0059] The concentration of doped metal ions was measured every 10 cm along the longitudinal direction of the prepared preform, and the longitudinal distribution diagram of the concentration of each metal ion along the fiber core was obtained. Cr 3+ Longitudinal concentration distribution as follows Figure 6 Fe 3+ Longitudinal concentration distribution as follows Figure 7 Co 2+ Longitudinal concentration distribution as follows Figure 8 .

[0060] The attenuated fiber preform prepared above was drawn into fibers using a drawing tower to obtain three attenuated fibers with different losses, labeled Fiber A, Fiber B, and Fiber C, corresponding to solutions A, B, and C, respectively. The absorption spectra of the three fibers in the 1250-1625 nm range were then measured. Figure 9 Fiber A's attenuation value meets LC5dB, such as Figure 10 The attenuation value of Fiber B meets LC10dB, such as Figure 11 The attenuation value of Fiber C meets LC15dB.

[0061] Considering the more diverse attenuation value requirements in production, the doping device in this invention expands to include more sets of solution wetting. In actual operation, it can be set according to the needs, which will not be elaborated here.

[0062] The gases and gas flow rates used in the cavity replacement, dehydration and drying, oxidation, and sintering steps of this invention can be adjusted by those skilled in the art according to actual needs, and will not be elaborated further here.

[0063] The aqueous solution of attenuating ion chloride mixture in this invention can be adjusted and configured by those skilled in the art according to actual needs, and will not be described in detail here.

[0064] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. Furthermore, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed in the present invention.

Claims

1. An apparatus for making an attenuated optical fiber preform by a VAD process, characterized by comprising: Including doping equipment and sintering equipment; The doping device includes several solution tanks, which are connected to a solution pump via pipes. The solution pump is connected to a solution spray head via pipes. Each solution spray head has isolation components on both sides. The solution spray head is fixed on a guide rail, which is used to drive the solution spray head to move back and forth within the length of the isolation components on both sides. A horizontal lathe is provided below the solution spray head; The sintering apparatus includes a sintering furnace, and the sintering furnace is equipped with a heating device.

2. An apparatus for making an attenuated optical fiber preform by the VAD process as claimed in claim 1, wherein, The isolation component is fixedly installed.

3. The apparatus for preparing attenuated optical fiber preforms using the VAD method as described in claim 1, characterized in that, The horizontal lathe is used to clamp and rotate the optical fiber preform at a speed of 0-20 rpm, so that the solution sprayed from the solution spray head can fully wet the optical fiber preform; the guide rail moves at a speed of 10-200 mm / min.

4. The apparatus for preparing attenuated optical fiber preforms using the VAD method as described in claim 1, characterized in that, The sintering apparatus is used to sinter the impregnated optical fiber preform.

5. A method for preparing attenuated fiber preforms using the VAD method, comprising the apparatus for preparing attenuated fiber preforms using the VAD method as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Prepare optical fiber preforms using the VAD method. The optical fiber preforms include a seed rod and a loose core layer covering the outside of the seed rod. Step 2: Prepare aqueous solutions of chlorides with different concentrations of decaying ions, and inject the aqueous solutions of different concentrations into different solution tanks of the doping device from left to right in order of increasing decaying ion concentration. Step 3: Install the prepared optical fiber preform onto the horizontal lathe of the doping device, start the doping device, and the solution spray head sprays the solution connected to each other onto the core loose layer. At the same time, each solution spray head only moves back and forth within the set stroke area within the length of the isolation parts on both sides until all core loose layers are completely wetted, and a longitudinally segmented core loose layer is obtained; then dry it on the horizontal lathe for 1-2 hours until there is no solution flow or dripping in the core loose layer. Step 4: Place the dried optical fiber preform into the sintering device. First, purge the cavity of the sintering device with nitrogen or an inert gas to replace the atmosphere. Then, purge with chlorine, helium, and nitrogen at 200℃-400℃ to dehydrate the loose core layer. Next, purge with oxygen and helium at 1000-1300℃ to oxidize the attenuating chloride ions in the loose core layer. Finally, continue to raise the temperature to 1800-2100℃ to sinter the loose core layer until it is transparent, thus obtaining a transparent core optical fiber preform. Step 5: Using the transparent core fiber preform as a seed rod, deposit a cladding porous body on its surface using the VAD method to obtain a quartz cladding porous body fiber preform. Step 6: Place the quartz clad loose fiber preform into the sintering apparatus. First, purge the cavity of the sintering apparatus with nitrogen or an inert gas to replace the atmosphere. Then, purge the loose clad with chlorine, helium, or nitrogen at 200℃-400℃ to dehydrate the loose clad. After that, raise the temperature to 1800-2200℃ and sinter the loose clad until it is transparent, obtaining a transparent attenuation fiber preform with a core and cladding structure.

6. The method for preparing attenuated optical fiber preforms using the VAD method as described in claim 5, characterized in that, The core layer is a porous material composed of silicon dioxide and germanium dioxide, and is doped with fluorine and phosphorus. The diameter of the core layer is 10-30 mm and the length is 600-1500 mm.

7. The method for preparing attenuated optical fiber preforms using the VAD method as described in claim 5, characterized in that, The core layer porous layer component includes silicon dioxide, with a porous body diameter of 10-120 mm and a length of 600-1500 mm.

8. The method for preparing attenuated optical fiber preforms using the VAD method as described in claim 5, characterized in that, The aqueous solution containing different concentrations of decaying ion chlorides includes CoCl2, aluminum chloride, and other co-doped decaying ion chlorides. The concentration of CoCl2 is 0.01%-0.75% by mass, the concentration of aluminum chloride is 1.5%-3.0% by mass, and the other co-doped decaying ion chlorides include one or more chlorides of Cr, Mn, Fe, Co, Ni, Cu, and Zn, with a concentration of 0.01%-1.2% by mass.

9. The method for preparing attenuated optical fiber preforms using the VAD method as described in claim 5, characterized in that, The attenuated fiber preform core obtained in step 6 has multiple segments with different attenuation values.

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