Hollow core fiber gas permeation device and method of resisting gas intrusion

Abstract

This invention provides a gas permeation device and a method for preventing gas intrusion into hollow optical fibers. The device includes a gas chamber comprising a chamber body and a chamber wall. The chamber body is used to hold the hollow optical fiber, and the chamber wall is provided with a sealed connector for connecting to an external gas path. A high-pressure gas source is used to connect to the sealed connector and provide permeation gas to the chamber. The type of permeation gas is determined by the cladding material and coating material of the hollow optical fiber. The morphology of the hollow optical fiber within the chamber allows its sides to contact the permeation gas. This invention uses a gas that has a permeating effect on optical fiber materials, permeating into the hollow optical fiber from its sides. The interaction area between the permeation gas and the optical fiber is proportional to the fiber length; therefore, the required processing time does not increase significantly with changes in fiber length, making it more suitable for processing long sections of hollow optical fibers and improving processing efficiency.

Description

Technical Field

[0001] This invention belongs to the field of hollow optical fiber technology, specifically relating to a gas permeation device for hollow optical fiber and a method for preventing gas intrusion. Background Technology

[0002] Hollow-core antiresonant fiber possesses a unique microstructure design that confines transmitted light waves within an air core, making it crucial for applications in fields such as light-filled material interactions, nonlinear optics, gas detection, gas laser generation, and optofluidics. Due to its unique structure and light-guiding mechanism, it achieves ultra-low Rayleigh scattering, low nonlinear coefficients, and tunable dispersion, providing a higher laser damage threshold and potential applications in high-power laser transmission, ultraviolet / mid-infrared light transmission, pulse compression, and optical soliton transmission. The ultra-low loss, low dispersion, low nonlinearity, and near-light-speed propagation of the air core enable the development of hollow-core fiber communication transmission and communication devices, laying the foundation for the construction and development of next-generation ultra-high-capacity, low-latency, and high-speed optical communication systems.

[0003] Hollow-core fiber, as a next-generation disruptive optical waveguide technology, possesses a unique hollow core structure that allows it to be filled with gases and liquids, giving it unique advantages in fields such as gas lasers, gas sensing, and quantum state transmission. However, this characteristic also brings negative impacts: during the fiber drawing process, due to thermal expansion and contraction, the pressure in the cooled core region is approximately 0.2 Bar lower than atmospheric pressure. This pressure difference provides the impetus for external gases to penetrate the fiber. For communication applications that must withstand the challenges of the natural environment, the intrusion of external gases causes light in the fiber core to interact with gas molecules, severely restricting the performance stability and reliability of hollow-core fiber. Specifically, the light absorption effect of water vapor (H2O) drastically increases the attenuation level of communication bands, significantly affecting the O, E, and S communication bands; carbon monoxide (CO) gas molecules exhibit characteristic absorption near 1575 nm; and carbon dioxide (CO2) gas molecules exhibit characteristic absorption near 1575 nm and 1605 nm, severely restricting communication transmission of hollow-core fiber in the L-band.

[0004] Existing methods for preventing gas intrusion in hollow optical fibers typically involve purging both ends of the fiber with high-pressure gas. For example, Chinese patent application CN119661100A discloses a method using a gas source containing mixed heavy water vapor to purge the interior of the hollow optical fiber, thereby achieving resistance to water peaks. This method is effective for shorter fibers. However, when the fiber length reaches several kilometers or tens of kilometers, the processing time required at the same gas pressure increases significantly, approximately proportional to the square of the fiber length. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention proposes a gas permeation device and anti-gas intrusion method for hollow optical fiber, thereby improving the processing efficiency of internal pressurization of hollow optical fiber.

[0006] To achieve the above objectives, according to one aspect of the present invention, a hollow optical fiber gas permeation apparatus is provided, comprising:

[0007] The gas chamber includes a chamber body and a chamber wall. The chamber body is used to place hollow optical fibers, and the chamber wall is provided with a sealed connector for connecting to the external gas path.

[0008] A high-pressure gas source is used to connect to the sealing joint and provide permeation gas to the cavity; the type of permeation gas is determined by the cladding material and coating material of the hollow optical fiber.

[0009] The shape of the hollow fiber within the cavity allows its sides to come into contact with the permeating gas.

[0010] According to the above scheme, at least one end of the hollow optical fiber is connected to an optical detection component for real-time monitoring of the gas state inside the hollow optical fiber.

[0011] According to the above scheme, the optical detection component is set in the cavity and connected to the hollow optical fiber through a connector.

[0012] According to the above scheme, the optical detection component is located outside the gas cavity; at least one end of the air optical fiber is connected to the outside of the gas cavity through a sealed joint and is connected to the optical detection component through a connector.

[0013] According to the above scheme, a pressure gauge is also included, which is connected to the gas path inside the cavity through a sealed joint, and is used to monitor the gas pressure inside the cavity in real time.

[0014] According to the above scheme, a vacuum pump is also included, which is connected to the gas path inside the cavity through a sealed joint.

[0015] According to the above scheme, the inner wall of the cavity is coated with an anti-gas permeation layer.

[0016] According to the above scheme, it also includes a temperature control device and a thermometer. The temperature control device is used to regulate the temperature inside the cavity, and the thermometer is used to monitor the temperature inside the cavity in real time.

[0017] According to the above scheme, the form of hollow optical fiber is: hollow optical fiber with a length of more than 1 km is coiled in a state with a diameter of more than 10 cm.

[0018] According to another aspect of the present invention, a method for resisting gas intrusion using the aforementioned hollow optical fiber gas permeation device is provided, comprising the following steps:

[0019] Hollow optical fiber is placed in the cavity, and permeation gas at a predetermined pressure is introduced by a high-pressure gas source;

[0020] Stop when the predetermined time is reached or the predetermined air pressure is reached inside the hollow optical fiber.

[0021] According to the above method, the type of permeating gas is determined by the cladding material and coating material of the hollow fiber; the predetermined pressure and predetermined time are obtained by combining the material and geometry of the cladding and coating of the hollow fiber, as well as the permeability of the permeating gas.

[0022] The operating temperature is also set using the above method. The operating temperature is obtained by combining the materials and geometric dimensions of the cladding and coating layers of the hollow optical fiber, as well as the permeability of the high-pressure gas.

[0023] Following the above method, after placing the hollow optical fiber in the cavity, the gas inside the cavity is first extracted, and then a permeation gas at a predetermined pressure is introduced through a high-pressure gas source.

[0024] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0025] 1. A gas that can penetrate optical fiber materials is used to penetrate into the hollow optical fiber from the side. The interaction area between the penetrating gas and the optical fiber is proportional to the length of the optical fiber. Therefore, the required processing time will not increase significantly with the change of optical fiber length, making it more suitable for processing long hollow optical fibers and improving processing efficiency.

[0026] 2. By employing optical detection components to monitor the gas state inside the hollow fiber in real time, a pressure gauge to monitor the gas pressure inside the cavity, and a thermometer to monitor the temperature inside the cavity, the state of the hollow fiber and the gas permeation device can be better adjusted during the processing.

[0027] 3. First, remove the gas from the cavity, and then perform gas permeation. This can improve the purity of the gas inside the hollow fiber, thereby improving the performance of the hollow fiber. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the device provided in Embodiment 1 of the present invention.

[0029] Figure 2 This is a flowchart of the method provided in Embodiment 1 of the present invention.

[0030] Figure 3 This is a schematic diagram of the device provided in Embodiment 2 of the present invention.

[0031] Figure 4 This is a schematic diagram of the device provided in Embodiment 3 of the present invention.

[0032] Figure 5 This is a schematic diagram of the device provided in Embodiment 4 of the present invention.

[0033] In the picture:

[0034] 1-High-pressure gas source, 2-Gas chamber, 201-Cavity body, 202-Pressure gauge, 203-Sealed joint, 3-Optical detection component, 301-Fiber optic pigtail, 302-Connector, 303-Optical time domain reflectometer, 4-Hollow fiber optic cable, 5-Vacuum pump. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0036] This invention proposes a gas permeation device and a method for preventing gas intrusion into hollow optical fibers. Gas permeation is widespread in solid materials. Due to the numerous irregular voids in the network structure of quartz glass, many gases can diffuse and permeate, especially gases with small atomic diameters such as helium, neon, and hydrogen, which have strong permeability in quartz glass. Since the gas permeation rate is proportional to the surface area of ​​the optical fiber, and the ratio of the fiber's surface area to its length is constant, the required processing time will not differ significantly for longer optical fibers. Therefore, this invention is more suitable for processing long sections of hollow optical fibers.

[0037] Example 1

[0038] Based on the above-described inventive concept, this embodiment provides a hollow optical fiber gas permeation device, such as... Figure 1 As shown, it includes a gas chamber 2 and a high-pressure gas source 1. The gas chamber 2 includes a cavity body 201 and a cavity wall. The cavity body 201 is used to house the hollow-core optical fiber 4, and the cavity wall is provided with a sealed connector 203 for connecting to the external gas path. The high-pressure gas source 1 is used to connect to the sealed connector 203 to provide permeation gas to the cavity body 201; the type of permeation gas is determined by the cladding material and coating material of the hollow-core optical fiber.

[0039] To allow the permeating gas to better penetrate from the surface of the hollow fiber 4, the shape of the hollow fiber 4 within the cavity 201 allows its sides to contact the permeating gas. For example, the hollow fiber can be a 5 km long hollow fiber wound in a 35 cm diameter fiber coil.

[0040] Continue as Figure 1As shown, one end of the hollow fiber 4 is connected to an optical detection component 3 for real-time monitoring of the gas state inside the hollow fiber 4. In this embodiment, the optical detection component 3 is located outside the gas cavity 2 and includes an optical time-domain reflectometer 303, a pigtail 301, and a connector 302 connected in sequence. Both ends of the hollow fiber 4 are connected to the outside of the gas cavity 2 through sealing connectors 203. One end is connected to the optical detection component 3 through the connector 302, and the other end is sealed to prevent the intrusion of external impurity gases.

[0041] Continue as Figure 1 As shown, in some embodiments, a pressure gauge 202 may also be included, which is connected to the air passage inside the cavity 201 via a sealing joint 203, for real-time monitoring of the air pressure inside the cavity 201.

[0042] Furthermore, in order to prevent gas from easily permeating out of the gas cavity during the permeation of the hollow optical fiber, the inner wall of the cavity is coated with an anti-gas permeation layer.

[0043] In addition, to meet the temperature requirements during the permeation process, a temperature control device and a thermometer may also be included. The temperature control device is used to regulate the temperature inside the cavity, and the thermometer is used to monitor the temperature inside the cavity in real time.

[0044] like Figure 2 As shown, this embodiment also provides a method for resisting gas intrusion using the aforementioned hollow optical fiber gas permeation device, comprising the following steps:

[0045] S1. Select the permeation gas based on the cladding and coating materials of the hollow-core optical fiber. The permeation gas can be helium, hydrogen, deuterium, neon, argon, oxygen, or nitrogen, or any combination thereof. The pressure of the permeation gas is greater than 2 Bar, preferably greater than 10 Bar. The permeability of the permeation gas to quartz glass at room temperature and pressure is greater than 1 × 10⁻⁶. -13 cm 3 ·cm / cm 2 ·s·Pa.

[0046] S2. Based on the material and geometry of the cladding and coating of the hollow fiber, as well as the permeability of the selected permeation gas, calculate the required time, permeation gas pressure, and temperature.

[0047] S3. Place the hollow optical fiber in the cavity, set the working temperature, and introduce permeation gas at a predetermined pressure through a high-pressure gas source.

[0048] S4. Stop when the predetermined time is reached or the predetermined air pressure is reached inside the hollow fiber.

[0049] In this embodiment, the cladding and coating materials of the hollow-core optical fiber 4 are acrylic resin. The hollow-core optical fiber has an outer diameter of 250 μm, an inner diameter of 100 μm, a length of 5 km, and is coiled on an optical fiber spool with a diameter of 20 cm. Helium was selected as the permeation gas, and the optical fiber was permeated at a pressure of 1 MPa and a temperature of 30°C. Real-time testing with an OTDR optical detector showed that after 70 hours of permeation, the internal pressure of the hollow-core optical fiber recovered from negative pressure to normal pressure. The permeability of the selected permeation gas is much greater than that of the impurity gas, and no additional gas absorption loss is introduced.

[0050] This method is used immediately after hollow-core optical fiber fabrication, especially immediately after fabrication, to restore the internal gas pressure from negative to normal. After this anti-gas intrusion treatment, the hollow-core optical fiber is then deployed to the application scenario. This prevents external impurities from entering the fiber during the period from manufacturing to application, ensuring the purity and pressure of the internal gas and thus improving the performance of the hollow-core optical fiber in subsequent applications.

[0051] Example 2

[0052] like Figure 3 The principle and structure of this embodiment are basically the same as those of Embodiment 1, except that it also includes a vacuum pump 5. The vacuum pump 5 is connected to the internal gas path of the cavity 201 via a sealing joint 203. The function of the vacuum pump 5 is to remove residual impurity gases from inside the cavity 201 before introducing high-purity, high-pressure permeation gas.

[0053] Example 3

[0054] like Figure 4 The principle and structure of this embodiment are basically the same as those of Embodiment 1, except that both ends of the hollow optical fiber 4 are connected to the optical detection component 3 via connectors 302. This embodiment can accurately measure the internal air pressure distribution.

[0055] Example 4

[0056] like Figure 5 The principle and structure of this embodiment are basically the same as those of Embodiment 1. The difference is that both ends of the hollow fiber 4 are placed in the cavity 201, and the optical detection component 3 is also placed in the cavity 201 and connected to the hollow fiber 4 through the connector 302. Since the ends of the hollow fiber 4 are not sealed, in addition to permeating into the hollow fiber 4 from the side, the permeating gas can also enter the interior of the hollow fiber 4 from the end face, forming a local high-pressure gas distribution, which more effectively protects the hollow fiber 4 from the intrusion of external gases.

[0057] This invention proposes a gas permeation device and a method for resisting gas intrusion in hollow optical fibers, which is used to restore the gas pressure inside the hollow optical fiber from negative pressure to normal pressure or above, thereby improving the resistance to gas intrusion, improving the transmission performance of the hollow optical fiber, and ensuring the long-term stability of the hollow optical fiber in application scenarios.

[0058] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0059] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. 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 present invention.

Claims

1. A hollow optical fiber gas permeation device, characterized in that: include: The gas chamber includes a chamber body and a chamber wall. The chamber body is used to place hollow optical fibers, and the chamber wall is provided with a sealed connector for connecting to the external gas path. A high-pressure gas source is used to connect to the sealing joint and provide permeation gas to the cavity; the type of permeation gas is determined by the cladding material and coating material of the hollow optical fiber. The shape of the hollow fiber within the cavity allows its sides to come into contact with the permeating gas.

2. The hollow optical fiber gas permeation device according to claim 1, characterized in that: At least one end of the hollow optical fiber is connected to an optical detection component for real-time monitoring of the gas state inside the hollow optical fiber.

3. The hollow optical fiber gas permeation device according to claim 2, characterized in that: The optical detection component is housed in the cavity and connected to the hollow optical fiber via a connector.

4. The hollow optical fiber gas permeation device according to claim 2, characterized in that: The optical detection assembly is located outside the gas chamber; at least one end of the air optical fiber is connected to the outside of the gas chamber through a sealed connector and is connected to the optical detection assembly through a connector.

5. The hollow optical fiber gas permeation device according to claim 1, characterized in that: It also includes a pressure gauge, which is connected to the gas path inside the cavity via a sealed connector, for real-time monitoring of the gas pressure inside the cavity.

6. The hollow optical fiber gas permeation device according to claim 1, characterized in that: It also includes a vacuum pump, which is connected to the gas path inside the cavity via a sealed connector.

7. The hollow optical fiber gas permeation device according to claim 1, characterized in that: The inner wall of the cavity is coated with a gas-impermeable layer.

8. The hollow optical fiber gas permeation device according to claim 1, characterized in that: It also includes a temperature control device and a thermometer. The temperature control device is used to regulate the temperature inside the cavity, and the thermometer is used to monitor the temperature inside the cavity in real time.

9. The hollow optical fiber gas permeation device according to claim 1, characterized in that: The form of hollow optical fiber is: hollow optical fiber with a length of more than 1 km is coiled in a state with a diameter of more than 10 cm.

10. A method for resisting gas intrusion using the hollow optical fiber gas permeation device according to claim 1, characterized in that: Includes the following steps: Hollow optical fiber is placed in the cavity, and permeation gas at a predetermined pressure is introduced by a high-pressure gas source; Stop when the predetermined time is reached or the predetermined air pressure is reached inside the hollow optical fiber.

11. The method for preventing gas intrusion according to claim 10, characterized in that: The type of permeating gas is determined by the cladding and coating materials of the hollow fiber; the predetermined pressure and time are obtained by combining the materials and geometry of the cladding and coating of the hollow fiber with the permeability of the permeating gas.

12. The method for preventing gas intrusion according to claim 10, characterized in that: The operating temperature is also set, which is obtained by combining the materials and geometry of the cladding and coating layers of the hollow fiber, as well as the permeability of the permeating gas.

13. The method for preventing gas intrusion according to claim 10, characterized in that: After the hollow optical fiber is placed in the cavity, the gas inside the cavity is first extracted, and then a permeation gas at a predetermined pressure is introduced through a high-pressure gas source.

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