Liquid phase deuterium-doped anti-radiation optical fiber, preparation method and application

Abstract

The invention discloses a liquid-phase deuterium-doped anti-radiation optical fiber, a preparation method and application, and belongs to the technical field of manufacturing of anti-radiation optical fibers. According to the method, deuterium is stably doped into a fiber core in the form of OD groups in the preparation stage of the optical fiber preform through an improved chemical vapor deposition combined solution doping technology, so that the problems that gas is easy to leak and the radiation resistance is attenuated along with time in a traditional gas loading technology are solved. The preparation process comprises the steps of pretreatment of the deposition tube, preparation of the barrier layer and the porous loose layer, solution soaking OD group doping, sintering collapse and wire drawing treatment. An OD group can be detected in the prepared optical fiber, the radiation resistance of the optical fiber is remarkably improved, after the optical fiber is irradiated by gamma rays with the total dose of 200Gy (Si), the radiation-induced attenuation is remarkably lower than that of a common optical fiber without the OD group, and a material basis is provided for long-term reliable application of the optical fiber in radiation environments such as space exploration and nuclear facilities.

Description

Technical Field

[0001] This invention relates to the field of optical fiber manufacturing technology, specifically to a liquid-phase deuterium-doped radiation-resistant optical fiber, its preparation method, and its application. Background Technology

[0002] Fiber lasers, with their excellent thermal management, high beam quality, and compact structure, have been widely used in biomedicine, communication sensing, and industrial processing. In recent years, their demand has been increasing in aerospace and nuclear facility applications such as satellite communication and gravitational wave detection. However, high-energy radiation (electrons, protons, gamma rays, etc.) in space and nuclear environments can induce radio-induced darkening in optical fibers, leading to reduced output power, transverse mode instability, and even laser burnout, severely limiting their reliability in radiation environments.

[0003] Radiation-induced darkening primarily originates from the formation of color centers in optical fibers. Rare-earth-doped fibers, serving as the gain medium for fiber lasers, are highly sensitive to radiation. Existing methods for improving the radiation resistance of optical fibers include composition optimization, Ce co-doping, thermal annealing, photobleaching, and gas loading. Among these, D2 loading is considered one of the most effective techniques due to its ability to effectively passivate radiation-induced color centers. However, this method has inherent drawbacks: D2 molecules easily escape from the fiber at room temperature and pressure, leading to a decay in radiation resistance over time, which cannot meet the requirements of long-term missions. To address the gas leakage problem, existing technologies have proposed hole-assisted carbon coatings and pre-treatment of preforms, but these methods suffer from complex preparation processes and high costs. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, this invention provides a liquid-phase deuterium-doped radiation-resistant optical fiber, its preparation method, and its application. This method can stably fix deuterium in the fiber core without D2 loading, effectively preventing deuterium from escaping from the fiber. This allows the optical fiber to maintain its radiation resistance performance stably for a long period of time and is a preparation technology that is easy to implement industrially.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows: A method for preparing a deuterium-doped, radiation-resistant optical fiber in liquid phase includes the following steps: (1) Barrier layer preparation: A silica barrier layer is formed by depositing and sintering on the inner surface of a quartz deposition tube; (2) Preparation of porous loose layer: A porous loose layer is formed by depositing in the quartz deposition tube obtained in the previous step; (3) Solution doping with OD groups: The quartz deposition tube treated in step (2) is immersed in a mixed solution containing doped ions and OD groups, so that the doped ions and OD groups are adsorbed on the surface of the porous layer and in the pores inside it, wherein the doped ions include Al³⁺. + , rare earth ions; (4) Drying treatment: The quartz deposition tube after step (3) is dried in an atmosphere of Cl2, He and O2; (5) Sintering and vitrification: A mixture of O2 and He gas is introduced into the quartz deposition tube after step (4) for sintering and vitrification; (6) Repeat steps (2)-(5) 2-5 times; (7) Collapse into rod: The O2 and He mixture is introduced into the quartz deposition tube finally obtained in step (6) and collapsed into a solid optical fiber preform. (8) Sleeve drawing and coating: The solid optical fiber preform is sleeved and then drawn into an optical fiber. After coating and UV curing, it is wound up to make a radiation-resistant optical fiber. The OD group content in the core of the obtained radiation-resistant optical fiber is not less than 30ppm.

[0006] On the other hand, a radiation-resistant optical fiber is provided, which is prepared based on the liquid-phase deuterium-doped radiation-resistant optical fiber preparation method. Further, the radiation-resistant optical fiber can be ytterbium-doped fiber, erbium-doped fiber, erbium-ytterbium co-doped fiber, thulium-doped fiber, holmium-doped fiber, neodymium-doped fiber, pure silica fiber, etc., and the OD group content in its core is not less than 30 ppm.

[0007] On the other hand, the above-mentioned radiation-resistant optical fiber is provided for application in satellite communication equipment, lidar equipment, or nuclear facility detection equipment.

[0008] This invention solves the problem of deuterium leakage in traditional D2 loading technology by stably incorporating deuterium into the fiber core in the form of OD groups during the preform preparation stage, thereby achieving long-term stability of the radiation resistance performance of optical fibers.

[0009] Compared with the prior art, the beneficial effects of the present invention are: This invention introduces OD groups directly into the fiber core of an optical fiber preform using solution doping technology. The OD groups exist in a stable chemical bond form, which physically and permanently passivates the defects in the glass network that are easily excited by radiation. This completely solves the problem of deuterium leakage in traditional D2 loading, and enables the optical fiber to maintain a low level of optical transmission loss and laser output efficiency decay after being subjected to high-energy radiation such as gamma rays. This solves the key problem of irreversible degradation of optical fiber performance under high-irradiation environment and achieves long-term stability of radiation resistance performance.

[0010] Specifically, by solution doping with OD groups, the porous quartz deposited tube obtained after step (2) is immersed in a mixed solution containing doped ions and OD groups, allowing the doped ions and OD groups to adsorb onto the surface and pores of the porous layer. Utilizing the nano-sponge effect of the porous layer, OD groups are directly embedded into the glass precursor through solution doping, achieving in-situ chemical bonding between OD and the Si-O network during subsequent high-temperature sintering, thus realizing deep bonding of the OD groups.

[0011] Solution doping technology enables a more uniform distribution of OD groups in the fiber core, which more effectively suppresses color center formation compared to gas diffusion, resulting in significant radiation resistance. Compared to post-treatment technologies such as carrier gas treatment, which require regular maintenance or whose performance degrades over time, the OD groups introduced by chemical bonding in this method are extremely stable, non-volatile, and non-bleachable, and their radiation resistance is permanent, making them particularly suitable for extreme environments such as space and nuclear facilities where long-term unattended maintenance is required.

[0012] The preparation process of this invention is compatible with traditional MCVD technology, requires no major equipment modifications, has low production costs, and is suitable for large-scale production.

[0013] The optical fiber prepared by this invention can maintain good laser output performance under radiation environment and can be widely used in extreme environments such as satellite communication, lidar, and nuclear facility detection. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in this invention or the prior art, the 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 this invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0015] Figure 1 A flowchart illustrating a method for fabricating a radiation-resistant optical fiber based on liquid-phase deuterium doping, as provided in one embodiment; Figure 2 Micro-infrared spectra of the optical fiber preforms in each embodiment and comparative example; Figure 3 The images show the radiation-induced attenuation spectra of optical fibers prepared in each embodiment and comparative example after irradiation. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] To address the shortcomings of existing technologies, this invention introduces OD groups into the fiber core using solution doping technology, successfully solving the problem of easy leakage of traditional deuterium-loaded gas and improving the long-term stability of the fiber's radiation resistance.

[0018] In one embodiment, a method for preparing a deuterium-doped, radiation-resistant optical fiber in liquid phase is provided, comprising the following steps: (1) Barrier layer preparation: A silica barrier layer is formed by depositing and sintering on the inner surface of a quartz deposition tube; (2) Preparation of porous loose layer: A porous loose layer is formed by depositing in the quartz deposition tube obtained in the previous step; (3) Solution doping with OD groups: The quartz deposition tube treated in step (2) is immersed in a mixed solution containing doped ions and OD groups, so that the doped ions and OD groups are adsorbed on the surface of the porous layer and in the pores inside it, wherein the doped ions include Al³⁺. + , rare earth ions; (4) Drying treatment: The quartz deposition tube after step (3) is dried in an atmosphere of Cl2, He and O2; (5) Sintering and vitrification: A mixture of O2 and He gas is introduced into the quartz deposition tube after step (4) for sintering and vitrification; (6) Repeat steps (2)-(5) 2-5 times; (7) Collapse into rod: The O2 and He mixture is introduced into the quartz deposition tube finally obtained in step (6) and collapsed into a solid optical fiber preform. (8) Sleeve drawing and coating: The solid optical fiber preform is sleeved and then drawn into an optical fiber. After coating and UV curing, it is wound up to make a radiation-resistant optical fiber. The OD group content in the core of the obtained radiation-resistant optical fiber is not less than 30ppm.

[0019] MCVD refers to modified chemical vapor deposition, a widely used process in this field. The process involves connecting the left end of a quartz deposition tube to a feed system and the right end to a waste gas treatment device. The feed system, heated electrically, uses a bubbling method to deliver SiCl4 or / and POCl3 vapor along with high-purity O2 into the quartz deposition tube. An oxyhydrogen flame torch located below the quartz deposition tube heats the tube at a controllable speed and temperature, causing a high-temperature chemical reaction in the raw materials. Under the effect of thermophoresis, the raw materials are uniformly deposited on the inner surface of the quartz deposition tube. In the above embodiments, steps (1) and (2) both utilize MCVD to achieve the deposition of a silica barrier layer and a porous layer.

[0020] Specifically, in one embodiment of a method for preparing a liquid-phase deuterium-doped radiation-resistant optical fiber, in step (1), a quartz deposition tube is selected as the substrate. After polishing its surface, it is horizontally mounted on an MCVD lathe. SiCl4 vapor and O2 are mixed and introduced into the quartz deposition tube by a bubbling method. The tube is then heated using an oxyhydrogen flame torch to deposit and sinter a silicon dioxide barrier layer on the inner surface of the quartz deposition tube. Further, in step (1), the purity of O2 is ≥99.9999%, and the oxyhydrogen flame torch is used to heat the tube at a controllable speed of 100 mm / min to 130 mm / min. The silicon dioxide barrier layer is deposited and sintered at 1800℃ to 2000℃.

[0021] Specifically, in one embodiment of a method for preparing a liquid-phase deuterium-doped radiation-resistant optical fiber, in step (2), SiCl4 and POCl3 vapors are mixed with O2 and introduced into the quartz deposition tube obtained in the previous step by a bubbling method. The mixture is then heated using an oxyhydrogen flame torch, depositing the mixture within the quartz deposition tube to form a porous layer. Further, in step (2), the purity of O2 is ≥99.9999%, and the oxyhydrogen flame torch is used to heat the mixture at a controllable speed of 60 mm / min to 150 mm / min, depositing the mixture within the quartz deposition tube at 1500℃ to 1700℃ to form a porous layer.

[0022] Specifically, in one embodiment of a method for preparing a liquid-phase deuterium-doped radiation-resistant optical fiber, in step (3), the rare earth ions in the mixed solution are Yb³. + Er³ + Tm³ + Ho³ + 、Nd³ + At least one of the rare earth ions or none of the rare earth ions are present. Thus, the radiation-resistant optical fiber obtained can be ytterbium-doped fiber, erbium-doped fiber, erbium-ytterbium co-doped fiber, thulium-doped fiber, holmium-doped fiber, neodymium-doped fiber, pure silica fiber, etc. It can be understood that if the mixed solution in step (3) does not contain rare earth ions, then the radiation-resistant optical fiber finally obtained is pure silica fiber.

[0023] In another embodiment, in step (3), the rare earth ions in the mixed solution may also include Yb³. + Er³ + Tm³ + Ho³ + 、Nd³ + The mixed solution may also include at least one of the following: Al³⁺ + P 5+ At least one of them.

[0024] Further, in any of the above embodiments, in step (3), the OD group in the mixed solution is obtained by adding a compound containing the OD group, the compound containing the OD group includes a deuterated compound, the deuterated compound includes but is not limited to D2O, the single soaking time is 15min~30min, and the soaking temperature is 15℃~35℃.

[0025] Furthermore, in any of the above embodiments, in step (4), the drying process lasts for 30 min to 60 min and the drying temperature is 500℃ to 1000℃.

[0026] Furthermore, in any of the above embodiments, in step (5), the pressure inside the tube is controlled at 30Pa~80Pa, the overall gas flow rate inside the tube is 100Sccm~1000Sccm, to ensure that the OD groups are stably fixed in the fiber core, and the shrinkage temperature is 1900℃~2300℃.

[0027] In one embodiment, a radiation-resistant optical fiber is provided, prepared based on the liquid-phase deuterium-doped radiation-resistant optical fiber preparation method provided in any of the above embodiments. The radiation-resistant optical fiber can be ytterbium-doped fiber, erbium-doped fiber, erbium-ytterbium co-doped fiber, thulium-doped fiber, holmium-doped fiber, neodymium-doped fiber, pure silica fiber, etc., with an OD group content in its core of not less than 30 ppm.

[0028] like Figure 1 As shown, Figure 1 The flowchart illustrates a method for fabricating a radiation-resistant optical fiber based on liquid-phase deuterium doping, as provided in one embodiment. The fabrication process includes the following steps: (1) Preparation of barrier layer: Quartz deposition tube is selected as substrate. After polishing its surface, it is horizontally mounted on MCVD lathe. SiCl4 vapor and high-purity O2 are mixed and introduced into the deposition tube by bubbling method. The silicon dioxide barrier layer is deposited and sintered by heating with oxyhydrogen flame torch.

[0029] Specifically, in step (1), the surface of the quartz deposition tube is polished and straightened using an oxyhydrogen flame torch, and then placed horizontally on an MCVD lathe. A mixture of SiCl4 vapor and high-purity O2 (O2 purity ≥ 99.9999%) is introduced into the deposition tube at 1800℃~2000℃. The oxyhydrogen flame torch is slowly moved from the inlet to the outlet to heat the tube, depositing and sintering a silica barrier layer to prevent impurities in the reaction tube from diffusing into the core layer at high temperatures. This ensures the ultra-high purity of the core matrix, which is a prerequisite for achieving low intrinsic loss and high radiation resistance. The main chemical reaction equations involved are as follows:

[0030] (2) Preparation of porous loose layer: SiCl4 and POCl3 vapors are mixed with high-purity O2 by bubbling and introduced into the quartz deposition tube obtained in the previous step. The porous loose layer is formed by heating with an oxyhydrogen flame torch.

[0031] Specifically, in step (2), an oxyhydrogen flame torch is moved from the inlet to the outlet, and SiCl4 and POCl3 vapors, along with high-purity O2 (O2 purity ≥ 99.9999%), are simultaneously introduced into a quartz deposition tube with a pre-deposited silica barrier layer at 1500℃~1700℃, forming a white, opaque, porous layer. This porous layer is composed of incompletely sintered SiO2 framework, exhibiting a loose and porous structure, which can provide adsorption sites for subsequent liquid-phase solution doping of ions or groups. The main chemical reaction equations involved are as follows: ,

[0032] (3) Solution doping with OD groups: The quartz deposition tube obtained in step (2) is vertically immersed in an Al³⁺ solution. + In a mixed solution of rare earth ions and OD groups, doped Al³⁺ + Rare earth ions and OD groups are adsorbed on the surface and in the pores of the porous layer.

[0033] Specifically, in one embodiment, the rare earth ion selected is Yb. 3+ Step (3) includes: after naturally cooling the quartz deposition tube obtained in step (2) to room temperature, removing it from the MCVD lathe, and vertically immersing it in an Al-containing solution. 3+ Yb 3+ In solutions containing OD groups, Al 3 + Yb 3+ The solution is obtained by dissolving chlorides, and the OD group is obtained by adding compounds containing OD groups. The soaking time is 15 min to 30 min, and the soaking temperature is 15℃ to 35℃, so that the Al in the mixed solution... 3+ Yb3+ The OD groups adsorb onto the surface and pores of the porous layer. After soaking in the solution, the residual solution in the quartz deposition tube is drained, and then the resulting quartz deposition tube is reinstalled on the MCVD lathe.

[0034] (4) Drying treatment: The quartz deposition tube obtained in step (3) is reinstalled back into the MCVD lathe and dried in an atmosphere of Cl2, He and O2.

[0035] Specifically, the drying process in step (4) lasts for 30 min to 60 min and the drying temperature is 500℃ to 1000℃.

[0036] (5) Sintering and vitrification: A mixture of O2 and He gas is introduced into the quartz deposition tube obtained in step (4) for sintering and vitrification; Specifically, in step (5): the pressure inside the tube is controlled at 30~80Pa, the overall gas flow rate inside the tube is 100~1000Sccm, ensuring that the OD groups are stably fixed in the fiber core, and the sintering temperature is 1900℃~2300℃. During this process, the AlCl3, YbCl3 and other substances doped in the solution in step (3) will be converted into Al2O3 and Yb2O3, forming a transparent glassy state, mainly involving the following chemical reactions: ,

[0037] (6) Repeat steps (2)-(5) 2-5 times; (7) Collapse into rod: The O2 and He mixture is introduced into the quartz deposition tube obtained in step (6) and collapsed into a solid optical fiber preform. (8) Sheath drawing and coating: The solid optical fiber preform obtained in step (7) is sheathed and sent to the graphite high-temperature furnace of the drawing tower for melting and drawing. After coating and UV curing, it is wound up to make radiation-resistant optical fiber. The final radiation-resistant optical fiber has an OD group content of not less than 30ppm in the fiber core.

[0038] Specifically, step (6) includes: using a sleeve technology to fabricate a complete optical fiber preform from the solid optical fiber preform obtained in step (5). During the drawing stage, the optical fiber preform is fixed in the chuck of the feeding system and slowly fed into the graphite high-temperature furnace at a speed of 0.1 mm / min to 2 mm / min. After vacuuming, the position and insertion length of the optical fiber preform in the furnace are adjusted, and the furnace temperature is raised to 2000°C to 2300°C. After the lower end of the optical fiber preform melts and falls under gravity, the uneven part at its end is cut off, and then it is introduced into the drawing die. The initially drawn optical fiber is guided by a traction wheel, and its diameter is monitored in real time by an optical fiber diameter gauge to prepare an optical fiber that meets the size requirements, which is the final radiation-resistant optical fiber.

[0039] Accordingly, the present invention also provides an application of liquid-phase deuterium-doped radiation-resistant optical fiber in satellite communication, lidar, and nuclear facility detection.

[0040] The present invention, its effectiveness, and its superiority will be further described below through some embodiments and comparative examples.

[0041] Example 1: Embodiment 1 of the present invention provides a method for preparing a radiation-resistant optical fiber based on liquid-phase deuterium doping, comprising the following steps: (1) After polishing the surface of the quartz deposition tube, a silica barrier layer is deposited on its inner wall. 400 Sccm of SiCl4 and 800 Sccm of O2 are introduced into the deposition tube. The oxyhydrogen flame torch is slowly moved from the inlet end to the outlet end to maintain the temperature at 1900℃. (2) Pass 150 Sccm of SiCl4, 100 Sccm of POCl3, 500 Sccm of He and 600 Sccm of O2 into the quartz deposition tube obtained in the previous step, and use an oxyhydrogen flame torch to control the temperature at 1500℃ to form a porous and loose layer. (3) The deposited quartz tube obtained in step (2) is vertically immersed in an Al³⁺ solution. + Yb³ + The solution was immersed in a mixed solution of Al³ and OD groups at 25°C for 30 minutes. After draining the residual solution from the tube, it was removed. + The concentration for preparation is 0.5 mol / L to 4 mol / L, Yb³ + The concentration of the solution is 0.1 mol / L to 2 mol / L, and the OD group is prepared using 100% heavy water as the solvent. (4) Place the quartz deposition tube soaked in step (3) on an MCVD lathe, introduce 200 Sccm of Cl2, 400 Sccm of He and 600 Sccm of O2, and heat to 800℃ to dry the deposition tube. (5) Introduce 400 Sccm of O2 and 100 Sccm of He into the quartz deposition tube after drying in step (4), and perform sintering and vitrification at 2000℃. (6) Repeat steps (2) to (5) 3 times; (7) The quartz deposition tube treated in step (6) is collapsed at 2150°C until the deposited high-purity material and the quartz tube are melted together into a solid optical fiber preform. (8) Insert the solid optical fiber preform into the octagonal quartz glass sleeve and draw it in the drawing tower to form a radiation-resistant ytterbium-doped optical fiber with a core diameter of 20 μm and a cladding diameter of 400 μm, wherein the temperature of the graphite high-temperature furnace in the drawing tower is controlled at 2000℃.

[0042] Example 2: Embodiment 2 of the present invention provides a method for preparing a radiation-resistant optical fiber based on liquid-phase deuterium doping, comprising the following steps: (1) After polishing the surface of the quartz deposition tube, a silica barrier layer is deposited on its inner wall. 400 Sccm of SiCl4 and 800 Sccm of O2 are introduced into the deposition tube. The oxyhydrogen flame torch is slowly moved from the inlet end to the outlet end to maintain the temperature at 1900℃. (2) Pass 150 Sccm of SiCl4, 100 Sccm of POCl3, 500 Sccm of He and 600 Sccm of O2 into the quartz deposition tube obtained in the previous step, and use an oxyhydrogen flame torch to control the temperature at 1500℃ to form a porous and loose layer. (3) The deposited quartz tube obtained in step (2) is vertically immersed in an Al³⁺ solution. + Yb³ + The solution was immersed in a mixed solution of Al³ and OD groups at 25°C for 30 minutes. After draining the residual solution from the tube, it was removed. + The concentration for preparation is 0.5 mol / L to 4 mol / L, Yb³ + The concentration of the solution is 0.1 mol / L to 2 mol / L. The OD group is prepared using 80% heavy water and 20% anhydrous ethanol as solvents. (4) Place the quartz deposition tube soaked in step (3) on an MCVD lathe, introduce 200 Sccm of Cl2, 400 Sccm of He and 600 Sccm of O2, and heat to 800℃ to dry the deposition tube. (5) Introduce 400 Sccm of O2 and 100 Sccm of He into the quartz deposition tube after drying in step (4), and perform sintering and vitrification at 2000℃. (6) Repeat steps (2) to (5) 3 times; (7) The quartz deposition tube treated in step (6) is collapsed at 2150°C until the deposited high-purity material and the quartz tube are melted together into a solid optical fiber preform. (8) Insert the solid optical fiber preform into the octagonal quartz glass sleeve and draw it in the drawing tower to form a radiation-resistant ytterbium-doped optical fiber with a core diameter of 20 μm and a cladding diameter of 400 μm, wherein the temperature of the graphite high-temperature furnace in the drawing tower is controlled at 2000℃.

[0043] The difference between Example 2 and Example 1 is that the concentration of the OD group in the mixed solution selected in step (3) is prepared with 80% heavy water and 20% anhydrous ethanol as solvents.

[0044] Example 3: Embodiment 3 of the present invention provides a method for preparing a radiation-resistant optical fiber based on liquid-phase deuterium doping, comprising the following steps: (1) After polishing the surface of the quartz deposition tube, a silica barrier layer is deposited on its inner wall. 400 Sccm of SiCl4 and 800 Sccm of O2 are introduced into the deposition tube. The oxyhydrogen flame torch is slowly moved from the inlet end to the outlet end to maintain the temperature at 1900℃. (2) Pass 150 Sccm of SiCl4, 100 Sccm of POCl3, 500 Sccm of He and 600 Sccm of O2 into the quartz deposition tube obtained in the previous step, and use an oxyhydrogen flame torch to control the temperature at 1500℃ to form a porous and loose layer. (3) The deposited quartz tube obtained in step (2) is vertically immersed in an Al³⁺ solution. + Yb³ + The solution was immersed in a mixed solution of Al³ and OD groups at 25°C for 30 minutes. After draining the residual solution from the tube, it was removed. + The concentration for preparation is 0.5 mol / L to 4 mol / L, Yb³ + The concentration of the solution is 0.1 mol / L to 2 mol / L. The OD group is prepared using 50% heavy water and 50% anhydrous ethanol as solvents. (4) Place the quartz deposition tube soaked in step (3) on an MCVD lathe, introduce 200 Sccm of Cl2, 400 Sccm of He and 600 Sccm of O2, and heat to 800℃ to dry the deposition tube. (5) Introduce 400 Sccm of O2 and 100 Sccm of He into the quartz deposition tube after drying in step (4), and perform sintering and vitrification at 2000℃. (6) Repeat steps (2) to (5) 3 times; (7) The quartz deposition tube treated in step (6) is collapsed at 2150°C until the deposited high-purity material and the quartz tube are melted together into a solid optical fiber preform. (8) Insert the solid optical fiber preform into the octagonal quartz glass sleeve and draw it in the drawing tower to form a radiation-resistant ytterbium-doped optical fiber with a core diameter of 20 μm and a cladding diameter of 400 μm, wherein the temperature of the graphite high-temperature furnace in the drawing tower is controlled at 2000℃.

[0045] The difference between Example 3 and Example 1 is that the concentration of the OD group in the mixed solution selected in step (3) is prepared with 50% heavy water and 50% anhydrous ethanol as solvents.

[0046] Comparative Example 1: Comparative Example 1 provides a method for preparing a radiation-resistant optical fiber based on liquid-phase deuterium doping, which includes the following steps: (1) After polishing the surface of the quartz deposition tube, a silica barrier layer is deposited on its inner wall. 400 Sccm of SiCl4 and 800 Sccm of O2 are introduced into the deposition tube. The oxyhydrogen flame torch is slowly moved from the inlet end to the outlet end to maintain the temperature at 1900℃. (2) Pass 150 Sccm of SiCl4, 100 Sccm of POCl3, 500 Sccm of He and 600 Sccm of O2 into the quartz deposition tube obtained in the previous step, and use an oxyhydrogen flame torch to control the temperature at 1500℃ to form a porous and loose layer. (3) The deposited quartz tube obtained in step (2) is vertically immersed in an Al³⁺ solution. + Yb³ + The mixture was immersed in a solution at 25°C for 30 minutes, and after draining the residual solution from the tube, it was removed. Al³⁺ was then extracted. + The concentration for preparation is 0.5 mol / L to 4 mol / L, Yb³ + The concentration of the solution is 0.1 mol / L to 2 mol / L, and the mixed solution is prepared using anhydrous ethanol as the solvent. (4) Place the quartz deposition tube soaked in step (3) on an MCVD lathe, introduce 200 Sccm of Cl2, 400 Sccm of He and 600 Sccm of O2, and heat to 800℃ to dry the deposition tube. (5) Introduce 400 Sccm of O2 and 100 Sccm of He into the quartz deposition tube after drying in step (4), and perform sintering and vitrification at 2000℃. (6) Repeat steps (2) to (5) 3 times; (7) The quartz deposition tube treated in step (6) is collapsed at 2150°C until the deposited high-purity material and the quartz tube are melted together into a solid optical fiber preform. (8) Insert the solid optical fiber preform into the octagonal quartz glass sleeve and draw it in the drawing tower to form a radiation-resistant ytterbium-doped optical fiber with a core diameter of 20 μm and a cladding diameter of 400 μm, wherein the temperature of the graphite high-temperature furnace in the drawing tower is controlled at 2000℃.

[0047] The difference between Comparative Example 1 and Example 1 is that the mixed solution selected in step (3) does not contain OD groups, that is, the mixed solution uses anhydrous ethanol as a solvent.

[0048] The solid optical fiber preforms obtained in step (7) of Examples 1, 2, and 3 and Comparative Example 1 were cut and polished into thin slices with a thickness of 2 mm, and subjected to micro-infrared analysis with 32 scans and a resolution of 4 cm. 1 The coverage area is 4000cm 1 Up to 2000cm 1 The obtained micro-infrared spectrum is as follows Figure 2 As shown. By Figure 2 It can be seen that the optical fiber preforms obtained in Examples 1, 2, and 3 exhibit a peak at 2642 cm⁻¹ in their micro-infrared spectra. - The additional absorption band near ¹ corresponds to the fundamental vibration of the OD group. Therefore, Figure 2 This indicates that OD groups were successfully incorporated into the fiber core of the optical fiber preform through MCVD combined with solution doping technology.

[0049] The optical fibers prepared in Examples 1, 2, and 3, and Comparative Example 1 were subjected to gamma-ray irradiation at a dose rate of 1.5 Gy / min(Si) and a total dose of 200 Gy(Si). Then, the absorption coefficients of the different optical fibers before and after irradiation were measured using the truncation method, and the radiation-induced attenuation spectra were calculated. Figure 3 As shown.

[0050] Specifically, by Figure 3 It can be seen that the radiation-induced attenuation spectra of the radiation-resistant optical fibers prepared in Examples 1, 2 and 3 after irradiation with 200 Gy (Si) γ rays are significantly lower than those of Comparative Example 1. The relationship between the radiation-induced attenuation values ​​of the optical fibers prepared in Examples 1, 2 and 3 and Comparative Example 1 is: Comparative Example 1 > Example 3 > Example 2 > Example 1.

[0051] therefore, Figure 3 This indicates that incorporating OD groups into the core of ytterbium-doped fiber preforms can effectively improve the radiation resistance of ytterbium-doped fibers.

[0052] This invention introduces OD groups into the fiber core through MCVD combined with solution doping technology, successfully solving the problem of easy leakage of traditional deuterium-loaded gas and improving the long-term stability of the fiber's radiation resistance.

[0053] The radiation-resistant optical fiber based on liquid-phase deuterium doping provided by this invention has wide applications in satellite communication, lidar, nuclear facility detection and other fields.

[0054] In summary, unlike existing technologies, this invention provides a radiation-resistant optical fiber based on liquid-phase deuterium doping and its preparation method. The method includes: depositing a silica barrier layer on the inner wall of a quartz deposition tube; depositing a porous layer on the silica barrier layer; and then vertically immersing the quartz deposition tube with the porous layer in an Al³⁺-containing solution. +In a mixed solution of rare earth ions and OD groups, the OD groups are stably adsorbed onto the surface and pores of a porous layer. Subsequently, the preform is dried in an atmosphere of Cl2, He, and O2, followed by high-temperature sintering and collapse with O2 and He to form a solid optical fiber preform containing OD groups. Finally, it is sleeving, drawing, coating, and curing to produce a radiation-resistant optical fiber. This invention solves the problems of deuterium leakage and the decay of radiation resistance over time in traditional D2 loading by directly incorporating deuterium into the fiber core in the form of OD groups during the optical fiber preform preparation stage. The OD groups are chemically bonded to the glass network, which can significantly enhance the structural stability of the optical fiber matrix, effectively suppress the formation of radiation-induced color center precursors, and thus improve the long-term tolerance of the optical fiber to radiation environments such as gamma rays and protons. This method is compatible with traditional MCVD technology and is applicable to various rare earth-doped optical fibers such as ytterbium-doped, erbium-doped, and thulium-doped fibers, as well as pure silica optical fibers. It can be widely used in extreme radiation environments such as satellite communication, lidar, and nuclear facility monitoring, providing a reliable technical approach for the development of high-performance radiation-resistant optical fibers.

[0055] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0056] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for preparing deuterium-doped radiation-resistant optical fiber in liquid phase, characterized in that, Includes the following steps: (1) Barrier layer preparation: A silica barrier layer is formed by depositing and sintering on the inner surface of a quartz deposition tube; (2) Preparation of porous loose layer: A porous loose layer is formed by depositing in the quartz deposition tube obtained in the previous step; (3) Solution doping with OD groups: The quartz deposition tube treated in step (2) is immersed in a mixed solution containing doped ions and OD groups, so that the doped ions and OD groups are adsorbed on the surface of the porous layer and in the pores inside it, wherein the doped ions include Al³⁺. + , rare earth ions; (4) Drying treatment: The quartz deposition tube after step (3) is dried in an atmosphere of Cl2, He and O2; (5) Sintering and vitrification: A mixture of O2 and He gas is introduced into the quartz deposition tube after step (4) for sintering and vitrification; (6) Repeat steps (2)-(5) 2-5 times; (7) Collapse into rod: The O2 and He mixture is introduced into the quartz deposition tube finally obtained in step (6) and collapsed into a solid optical fiber preform. (8) Sleeve drawing and coating: The solid optical fiber preform is sleeved and then drawn into an optical fiber. After coating and UV curing, it is wound up to make a radiation-resistant optical fiber. The OD group content in the core of the obtained radiation-resistant optical fiber is not less than 30ppm.

2. The method for preparing deuterium-doped radiation-resistant optical fiber according to claim 1, characterized in that, In step (1), a quartz deposition tube is selected as the substrate. After polishing its surface, it is horizontally mounted on an MCVD lathe. SiCl4 vapor and O2 are mixed and introduced into the quartz deposition tube by bubbling. The tube is heated by an oxyhydrogen flame torch to deposit and sinter a silicon dioxide barrier layer on the inner surface of the quartz deposition tube.

3. The method for preparing deuterium-doped radiation-resistant optical fiber according to claim 2, characterized in that, In step (1), the purity of O2 is ≥99.9999%, and the hydrogen-oxygen flame torch is heated at a controllable speed of 100 mm / min to 130 mm / min to deposit and sinter at 1800℃ to 2000℃ to form a silicon dioxide barrier layer.

4. The method for preparing deuterium-doped radiation-resistant optical fiber in liquid phase according to claim 1, 2, or 3, characterized in that, In step (2), SiCl4 and POCl3 vapors are mixed with O2 and introduced into the quartz deposition tube obtained in the previous step by bubbling. The tube is heated by an oxyhydrogen flame torch to deposit a porous and loose layer.

5. The method for preparing deuterium-doped radiation-resistant optical fiber according to claim 4, characterized in that, In step (2), the purity of O2 is ≥99.9999%, and the hydrogen-oxygen flame torch is heated at a controllable speed of 60 mm / min to 150 mm / min. The O2 is deposited in the quartz deposition tube obtained in the previous step at 1500℃ to 1700℃ to form a porous and loose layer.

6. The method for preparing liquid-phase deuterium-doped radiation-resistant optical fiber according to claim 1, 2, 3, or 5, characterized in that, In step (3), the rare earth ions in the mixed solution are Yb³. + Er³ + Tm³ + Ho³ + 、Nd³ + At least one of them.

7. The method for preparing deuterium-doped radiation-resistant optical fiber according to claim 6, characterized in that, In step (3), the OD groups in the mixed solution are obtained by adding compounds containing OD groups, including deuterated compounds, including D2O, and the single soaking time is 15 min to 30 min, and the soaking temperature is 15℃ to 35℃.

8. The method for preparing liquid-phase deuterium-doped radiation-resistant optical fiber according to claim 1, 2, 3, 5, or 7, characterized in that, In step (4), the drying process lasts for 30 min to 60 min and the drying temperature is 500℃ to 1000℃. In step (5), the pressure inside the quartz deposition tube is controlled at 30Pa~80Pa, the overall gas flow rate inside the tube is 100Sccm~1000Sccm, and the OD groups are stably fixed in the fiber core. The sintering temperature is 1900℃~2300℃.

9. A radiation-resistant optical fiber, characterized in that, The optical fiber was prepared according to the method for preparing deuterium-doped liquid-phase radiation-resistant optical fiber as described in claim 1, 2, 3, 5, 7, or 9.

10. The application of the radiation-resistant optical fiber as described in claim 9, characterized in that, The radiation-resistant optical fiber is applied to satellite communication equipment, lidar equipment, or nuclear facility detection equipment.

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