High-power laser hollow fiber gas filling coupling terminal

Abstract

A high-power laser hollow fiber gas filling coupling terminal, comprising: a hollow fiber fixing component and a coupling terminal gas cavity cooling and circulating component. The hollow fiber fixing component includes a hollow fiber fixing end cap, a hollow fiber V-groove fixing piece, a hollow fiber V-groove fixing cover, a snap-fit V-groove pair, and a hollow fiber. The coupling terminal gas cavity cooling and circulating component includes a coupling terminal cooling and circulating system, a gas cavity main body, a coupling window mirror, and its fixing mirror cover. The coupling window mirror is fixed on the gas cavity main body. The hollow fiber fixing component is fixed on the axis of the coupling terminal gas cavity cooling and circulating component. The present invention can effectively absorb the laser energy leaked during the coupling process, avoid fiber damage caused by the leakage of laser energy, and at the same time can precisely control the air pressure inside the hollow fiber, laying a foundation for high-power fiber gas lasers.

Description

Technical Field

[0001] The present invention belongs to the fields of optical fiber technology and laser technology, and particularly relates to a high-power laser hollow fiber gas filling coupling terminal. Background Art

[0002] As a new type of special low-loss transmission optical fiber that has developed rapidly in recent years, the hollow fiber uses its special microstructure to confine light waves in a micron-scale air core for transmission, and has advantages such as low Rayleigh scattering, low nonlinearity, and low transmission loss. Therefore, it is widely used as an important light guiding device in high-power laser systems. When a specific gas is filled in the hollow fiber and externally pumped by a laser at the same time, a specific gas can be used as the gain medium of the laser to achieve the output of laser with a specific wavelength. Compared with solid-doped gain fibers, lasers with special gases as the gain medium can achieve laser output with a wider wavelength band and higher output power. In particular, high-power hollow fiber gas lasers have great potential application value in the fields of industrial processing, medical treatment, national defense, and military.

[0003] At present, gas lasers based on hollow fibers can be classified into several categories, mainly including spatial types and all-fiber types, etc. The all-fiber type hollow fiber gas laser realizes sealing by splicing the two ends of the hollow fiber with ordinary single-mode (or multi-mode) solid-core fibers respectively, and has the advantages of miniaturization and good stability. However, during the sealing process, the microstructure of the hollow fiber is damaged, resulting in an insertion loss of the gas cavity of more than 10 dB, and it is not suitable for high-power laser environments. The spatial type hollow fiber gas laser realizes the sealing of the cavity by placing the two ends of the hollow fiber into a sealed cavity with cavity pressure control, and at the same time couples the high-power laser beam into the hollow fiber through a spatial coupling method, and has the advantages of high coupling efficiency and easy control of the filling gas characteristics. However, the currently used sealed gas cavities are all relatively bulky and have poor heat dissipation performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-power laser gas filling coupling terminal based on a hollow fiber, which can efficiently couple a high-power laser beam into the hollow fiber, provide efficient heat dissipation, and prevent thermal damage of the hollow fiber during high-power laser transmission. And it can fill a specific gas into the hollow fiber and precisely control the filling air pressure, and at the same time can keep the microstructure of the cladding of the hollow fiber intact and the light guiding performance unchanged, and is particularly suitable for high-power gas lasers based on hollow fibers.

[0005] The specific technical solution adopted by the present invention is as follows:

[0006] A high-power laser-based hollow fiber gas filling coupling terminal, characterized in that it includes a hollow fiber fixing component and a coupling terminal gas cavity cooling and circulating component:

[0007] The described hollow-core fiber fixing component includes a hollow-core fiber fixing end cap, a hollow-core fiber V-groove fixing piece, a hollow-core fiber V-groove fixing cover, a snap-together V-groove pair, and a hollow-core fiber; the hollow-core fiber fixing end cap has a fiber through-hole in the sub-millimeter range, the hollow-core fiber V-groove fixing piece has a fiber through-hole in the sub-millimeter range, and the fiber through-holes are coaxial; the snap-together V-groove pair is composed of two V-grooves that snap together. When the snap-together V-grooves are snapped together, the hollow-core fiber is fixed on the axis of the snap-together V-groove pair; the snap-together V-groove pair is fixed inside the hollow-core fiber V-groove fixing piece and is coaxial with the fiber through-hole of the hollow-core fiber V-groove fixing piece, and is fastened by the hollow-core fiber V-groove fixing cover;

[0008] One end of the described hollow-core fiber extends outside the hollow-core fiber fixing component; the other end of the hollow-core fiber sequentially passes through the fiber through-hole of the hollow-core fiber fixing end cap, the fiber through-hole of the hollow-core fiber V-groove fixing piece, the central hole of the rubber gasket, and the fiber groove of the snap-together V-groove pair, and is interconnected with the gas chamber body;

[0009] The coupling terminal gas chamber cooling circulation component includes a coupling terminal cooling circulation system, a gas chamber body, a coupling window mirror, and a fixed mirror cover. The coupling window mirror is fixed inside the gas chamber body through the fixed mirror cover. The cooling circulation system is provided with a cooling inlet and a cooling outlet, and the connection line of the cooling inlet and the cooling outlet intersects the axis of the hollow-core fiber fixing component; the coupling terminal cooling circulation system is composed of a cooling inlet, a first cooling channel, a second cooling channel, a third cooling channel, a fourth cooling channel, a fifth cooling channel, and a cooling outlet that are sequentially connected. Both the second cooling channel and the fourth cooling channel are four independent cooling channels. The cooling inlet, the first cooling channel, and the second cooling channel are arranged on one side of the axis of the hollow-core fiber fixing component, and the fourth cooling channel, the fifth cooling channel, and the cooling outlet are arranged on the other side of the axis of the hollow-core fiber fixing component. The first cooling channel, the second cooling channel, and the fifth cooling channel intersect the axis of the hollow-core fiber fixing component;

[0010] The described hollow-core fiber fixing component is fixed on the central axis of the coupling terminal gas chamber cooling circulation component;

[0011] The gas chamber body is in a vacuum or special gas filling environment, and the inside of the hollow-core fiber is kept in a vacuum or special gas filling state by the action of air pressure difference;

[0012] The coupling terminal cooling circulation system is connected to the hollow-core fiber fixing component.

[0013] Preferably, the V-groove is made of pure quartz material.

[0014] Preferably, a V-shaped groove tangent to the hollow fiber is formed on one side of the V-groove, and one end of the V-groove is inclined with respect to the plane where the V-shaped groove is located, and the other end is perpendicular to the plane where the V-shaped groove is located; a high-transmission film is coated on the inclined end face; a high-reflection film is coated on the perpendicular end face.

[0015] Preferably, the pair of snap-fit V-grooves is composed of two V-grooves that snap together. When the snap-fit V-grooves are snapped together, the hollow fiber is fixed on the axis of the pair of snap-fit V-grooves.

[0016] Preferably, the pair of snap-fit V-grooves is fixed in the hollow fiber V-groove fixing member and fastened by the hollow fiber V-groove fixing cover.

[0017] Preferably, the hollow fiber fixing end cap and the hollow fiber V-groove fixing member both have fiber through holes on the sub-millimeter scale, and the fiber through holes are coaxial with the V-shaped grooves of the pair of snap-fit V-grooves.

[0018] Preferably, the hollow fiber fixing end cap and the hollow fiber V-groove fixing member are in conical surface fit, and a rubber gasket with a central hole is filled between them. The central hole of the rubber gasket is coaxial with the fiber through holes of the hollow fiber fixing end cap and the hollow fiber V-groove fixing member.

[0019] Preferably, the hollow fiber is fixed by the pair of snap-fit V-grooves, and the end face of the hollow fiber extends about 2-5 mm out of the snap-fit V-grooves.

[0020] Preferably, one end of the hollow fiber sequentially passes through the fiber through hole of the hollow fiber fixing end cap, the fiber through hole of the hollow fiber V-groove fixing member, the central hole of the rubber gasket, the V-shaped grooves of the pair of snap-fit V-grooves 204, and communicates with the gas chamber body.

[0021] Preferably, the hollow fiber fixing assembly is provided with a sealing groove for accommodating a sealing ring.

[0022] Preferably, the coupling terminal gas chamber cooling circulation assembly and the hollow fiber fixing assembly are sealed by the sealing ring.

[0023] Preferably, the coupling window mirror is fixed to the gas chamber body by the fixing mirror cover and the sealing gasket using fastening screws.

[0024] Preferably, the coupling terminal cooling circulation system is provided with a cooling inlet and a cooling outlet. The connection line between the cooling inlet and the cooling outlet intersects the axis of the hollow fiber fixing assembly. The cooling inlet and the cooling outlet are connected to an external cooling device through threaded joints.

[0025] Preferably, the gas cavity body is connected to the gas path of the gas distribution table through an air inlet / outlet with an inclined mouth seal thread. The gas in the gas cavity body is evacuated or filled through a vacuum pump and a gas source to be filled, and a vacuum or special gas filling environment inside the hollow fiber is achieved through the air pressure difference.

[0026] Preferably, the outer surface of the gas-filled coupling terminal of the hollow fiber is treated with a passivation process to avoid damage to personnel and instruments caused by laser reflection.

[0027] Preferably, the inside of the gas-filled coupling terminal of the hollow fiber remains smooth and clean.

[0028] Preferably, the gas-filled coupling terminal of the hollow fiber is fixed to the adjustment table with screws.

[0029] Advantages of the present invention:

[0030] 1. Using the V-groove made of pure quartz material for buckling can effectively leak the laser energy entering the cladding during the coupling process, thereby protecting the optical fiber and improving the beam quality of laser coupling transmission at the same time. 2. Using the circulating cooling system to cool the hollow fiber fixing assembly can timely remove the heat generated during the high-power laser coupling process, thereby protecting the hollow fiber and avoiding its thermal damage.

[0031] 3. Using the sub-millimeter fiber through-hole in the hollow fiber fixing assembly can effectively fix the position of the hollow fiber, avoid the movement of the end face of the hollow fiber, and thus maintain the stability of the high-power laser transmission performance of the hollow fiber.

[0032] 4. Through the gas cavity of the gas-filled coupling terminal and its gas inlet / outlet path, the filling air pressure of the specific gas inside the hollow fiber can be controlled in real time, ensuring the purity of the filled gas, and providing high efficiency gain and stable laser output performance for the gas laser.

[0033] 5. Using the gas-filled coupling terminal of the hollow fiber can effectively reduce the volume of the high-power gas fiber laser, realizing the miniaturization and integration of the high-power gas laser. Description of the Drawings

[0034] Figure 1 It is a cross-sectional view of the high-power coupling terminal of the hollow fiber;

[0035] Figure 2Schematic diagram of high-power V-groove;

[0036] Figure 3 Schematic diagram of hollow fiber fixing component;

[0037] Figure 4 Schematic diagram of coupling terminal gas chamber cooling component;

[0038] Figure 5 Schematic diagram of coupling terminal cooling circulation system;

[0039] Figure 6 Schematic diagram of gas filling system. Specific implementation mode

[0040] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than 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 work shall fall within the protection scope of the present invention.

[0041] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments described here can be implemented in an order different from that shown or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0042] Combined with Figure 1-4 , the present invention is based on a high-power gas-filled coupling terminal 1 for hollow fiber, including: a hollow fiber fixing component and a coupling terminal gas chamber cooling circulation component.

[0043] The described hollow fiber fixing component includes: a hollow fiber fixing end cap 201, a hollow fiber V-groove fixing member 202, a hollow fiber V-groove fixing cover 203, a snap-fit V-groove pair 204, and a hollow fiber 207.

[0044] The described coupling terminal gas chamber cooling circulation component includes a coupling terminal cooling circulation system, a gas chamber main body 309, a coupling window mirror 310, and a fixed mirror cover 312. The coupling window mirror 310 is fixed on the gas chamber main body 309.

[0045] The described hollow fiber fixing component is fixed on the axis of the coupling terminal gas cavity cooling circulation component.

[0046] The described snap - fit V - groove pair 204 is placed inside the hollow fiber V - groove fixing member 202 and fixed to the hollow fiber V - groove fixing member 202 with the hollow fiber V - groove fixing cover 203.

[0047] The described hollow fiber fixing end cap 201 and the hollow fiber V - groove fixing member 202 both have fiber through - holes 2011 and 2021 with sub - millimeter magnitudes, and the fiber through - holes 2011 and 2021 are coaxial with the fiber grooves 2041 of the snap - fit V - groove pair.

[0048] The described hollow fiber fixing end cap 201 is fixed on the axis of the hollow fiber V - groove fixing member 202 and has a tapered surface fit. At the same time, a rubber gasket 205 with a central hole is filled between the two, and the central hole of the rubber gasket is coaxial with the fiber through - hole.

[0049] The described hollow fiber 207 includes a fiber core 2071 and a coating layer 2072, and a section of the coating layer of the hollow fiber is stripped, and the stripping length exceeds the length of the snap - fit V - groove pair 204.

[0050] The stripped hollow fiber sequentially passes through the fiber through - hole 2011 of the hollow fiber fixing end cap, the central hole of the rubber gasket, and the fiber through - hole 2021 of the hollow fiber V - groove fixing member, is placed in the fiber groove 2041, and the hollow fiber is fixed by the snap - fit V - groove pair 204. And the end face of the hollow fiber 207 extends out of the hollow fiber V - groove fixing member 202 by about 2 - 5 mm.

[0051] The described hollow fiber fixing component is provided with a sealing groove 206 for accommodating a sealing ring.

[0052] The described coupling terminal gas cavity cooling circulation component and the hollow fiber fixing component are sealed by a sealing ring placed in the sealing groove.

[0053] The described coupling terminal cooling circulation system is provided with a cooling inlet 303 and a cooling outlet 302, and the connection line of the cooling inlet 303 and the cooling outlet 302 intersects with the axis of the hollow fiber fixing component;

[0054] In some embodiments, the coupling terminal cooling circulation system includes a first cooling channel 306, a second cooling channel, a third cooling channel 308, a fourth cooling channel, and a fifth cooling channel 307. The cooling inlet 303, the first cooling channel 306, the second cooling channel, the third cooling channel 308, the fourth cooling channel, the fifth cooling channel 307, and the cooling outlet 302 are communicated in sequence. The second cooling channel and the fourth cooling channel are respectively composed of 4 independent cooling channels (3051, 3052, 3053, 3054 and 3041, 3042, 3043, 3044). The cooling inlet 303, the first cooling channel 306, and the second cooling channel are arranged on one side of the axis of the hollow fiber fixed assembly. The fourth cooling channel, the fifth cooling channel 307, and the cooling outlet 302 are arranged on the other side of the axis of the hollow fiber fixed assembly. The first cooling channel 306, the second cooling channel, and the fifth cooling channel 307 intersect with the axis of the hollow fiber fixed assembly.

[0055] As Figure 5 As shown in the schematic diagram of the hollow fiber high-power coupling terminal cooling circulation, in a specific embodiment, the cooling path is realized in the following way: The external coolant enters the coupling terminal cooling circulation system through the cooling inlet 303, is divided into 4 cooling channels (3051, 3052, 3053, 3054) through the first cooling channel 306 and enters the fifth cooling channel 307, and then enters the cooling channels (3041, 3042, 3043, 3044) through the second cooling channel, and finally returns to the external cooling device through the cooling outlet 302.

[0056] In a specific embodiment, the air inlet 311 on the gas chamber main body 309 is an inclined mouth seal thread.

[0057] Figure 6 As shown in the schematic diagram of the hollow fiber gas filling system, the air inlet 311 is connected to the gas circuit of the gas distribution table 8 through an inclined mouth seal thread, and pure gas to be filled is filled into the hollow fiber 207 through the vacuum pump 6 and the gas source 7 to be filled.

[0058] In a specific embodiment, the gas filling process of the hollow-core optical fiber is achieved as follows: Seal both ends of the hollow-core optical fiber 207 into the high-power gas filling coupling terminal 1 based on the hollow-core optical fiber. Both gas filling coupling terminals 1 are equipped with pressure gauges 5 and are connected to the gas distribution station 8. The gas distribution station 8 with built-in valves is respectively connected to the vacuum pump 6 and the gas source 7 to be filled. During the gas filling process, first connect the hollow-core optical fiber 207 and the gas filling coupling terminal 1 to the vacuum pump 6 through the gas distribution station 8. After reaching the required vacuum degree, switch through the gas distribution station 8 to connect the gas source 7 to be filled and the gas filling coupling terminal 1 to each other, and control the air pressure entering the coupling terminal through the precisely controlled valve in the gas distribution station 8 according to the feedback of the pressure gauge 5. When the air pressure at both ends of the hollow-core optical fiber 207 stabilizes to the required pressure value, close all valves.

[0059] In a specific embodiment, during the gas filling process of the hollow-core optical fiber, the laser output by the laser 4 is coupled into the hollow-core optical fiber 207, and the output laser after the laser passes through the hollow-core optical fiber 207 is monitored throughout the process.

[0060] In some specific embodiments, the material of the hollow-core optical fiber fixing component is selected from copper alloy. It has good wear resistance and can ensure that the hollow-core optical fiber fixing component still has a high positioning accuracy after multiple plugging and unplugging operations. At the same time, copper alloy has excellent thermal conductivity and can conduct the heat generated inside the hollow-core optical fiber fixing component in time, thereby protecting the optical fiber and preventing it from suffering thermal damage.

[0061] In some specific embodiments, the outer surfaces of the hollow-core optical fiber gas filling coupling terminals 1 are all treated with a passivation process to avoid damage to personnel and instruments caused by the reflection of the incident laser.

[0062] In some specific embodiments, the inside of the hollow-core optical fiber gas filling coupling terminal 1 is kept smooth and clean, providing a good environment for the coupling of the hollow-core optical fiber and the laser.

[0063] In some specific embodiments, the hollow-core optical fiber gas filling coupling terminal 1 is fixed to the commonly used adjustment table in the optical experiment by screws, and through adjusting the optical adjustment table, efficient coupling with the laser light source is completed.

[0064] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0065] The above has introduced in detail a fiber optic coupling device for high-power laser fiber coupling provided by the present invention. For those of ordinary skill in the art, according to the idea of the embodiments of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A hollow fiber gas filling coupling terminal based on high-power laser, characterized in that It includes a hollow fiber fixing component and a coupling terminal gas chamber cooling and circulating component: The described hollow fiber fixing component includes a hollow fiber fixing end cap (201), a hollow fiber V-groove fixing part (202), a hollow fiber V-groove fixing cover (203), a snap-fit V-groove pair (204), and a hollow fiber (207); the hollow fiber fixing end cap (201) has a first fiber through-hole (2011) of sub-millimeter magnitude, the hollow fiber V-groove fixing part (202) has a second fiber through-hole (2021) of sub-millimeter magnitude, and the first fiber through-hole (2011) and the second fiber through-hole (2021) are coaxial; the snap-fit V-groove pair (204) is composed of two mutually snap-fitting V-grooves. When the snap-fit V-groove pair (204) is snap-fitted, the hollow fiber (207) is fixed on the axis of the snap-fit V-groove pair (204); the snap-fit V-groove pair (204) is fixed within the hollow fiber V-groove fixing part (202) and is coaxial with the second fiber through-hole (2021) of the hollow fiber V-groove fixing part, and is fastened by the hollow fiber V-groove fixing cover (203); One end of the described hollow fiber (207) extends outside the hollow fiber fixing component; the other end of the hollow fiber (207) sequentially passes through the first fiber through-hole (2011) of the hollow fiber fixing end cap (201), the second fiber through-hole (2021) of the hollow fiber V-groove fixing part (202), the central hole of the rubber gasket (205), and the fiber groove (2041) of the snap-fit V-groove pair (204), and is interconnected with the gas chamber body (309); The described coupling terminal gas chamber cooling circulation component includes a coupling terminal cooling circulation system, a gas chamber main body (309), a coupling window mirror (310), and a fixed mirror cover (312). The coupling window mirror (310) is fixed within the gas chamber main body (309) through the fixed mirror cover (312). The cooling circulation system is provided with a cooling inlet (303) and a cooling outlet (302). The connection line of the cooling inlet (303) and the cooling outlet (302) intersects the axis of the hollow fiber fixing component. The coupling terminal cooling circulation system is composed of a cooling inlet (303), a first cooling channel (306), a second cooling channel, a third cooling channel (308), a fourth cooling channel, a fifth cooling channel (307), and a cooling outlet (302) that are connected in sequence. Both the second cooling channel and the fourth cooling channel are four mutually independent cooling channels. The cooling inlet (303), the first cooling channel (306), and the second cooling channel are arranged on one side of the axis of the hollow fiber fixing component. The fourth cooling channel, the fifth cooling channel (307), and the cooling outlet (302) are arranged on the other side of the axis of the hollow fiber fixing component. The first cooling channel (306), the second cooling channel, and the fifth cooling channel (307) intersect the axis of the hollow fiber fixing component. The described hollow fiber fixing component is fixed on the central axis of the coupling terminal gas chamber cooling circulation component. The gas chamber main body (309) is in a vacuum or a special gas-filled environment, and the inside of the hollow fiber (207) is maintained in a vacuum or a special gas-filled state by the action of air pressure difference. The special gas is selected from helium, neon, argon, hydrogen, or a mixed gas of several of them. The coupling terminal cooling circulation system is connected to the hollow fiber fixing component.

2. The gas-filled coupling terminal according to claim 1, wherein The hollow fiber (207) is a special fiber with an air-filled core.

3. The gas-filled coupling terminal according to claim 2, wherein The hollow fiber (207) is a hollow bandgap fiber, a hollow Kagome fiber, or a hollow anti-resonant fiber.

4. The gas-filled coupling terminal according to claim 1, wherein The V-groove is made of pure quartz material.

5. The gas-filled coupling terminal according to claim 4, wherein, One side of the buckling V-groove pair (204) is provided with a fiber groove (2041) tangent to the hollow fiber. The fiber groove (2041) is on the axis of the V-groove.

6. The gas-filled coupling terminal according to claim 4, characterized in that, One end of the V-groove forms an inclined angle with the surface of the fiber groove (2041). The other end opposite to the inclined end of the V-groove is perpendicular to the surface where the fiber groove (2041) is located. The inclined end face is coated with a high-transmission film, and the perpendicular end face is coated with a high-reflection film.

7. The gas-filled coupling terminal according to claim 1, characterized in that, The hollow-core fiber fixed end cap (201) and the hollow-core fiber V-groove fixture (202) are positioned in a tapered surface fit. A rubber gasket (205) is filled between them and fastened with screws; the rubber gasket (205) is provided with a central hole, the diameter of the central hole is slightly smaller than the diameter of the hollow-core fiber, and the hollow-core fiber can pass through the central hole due to the deformation of the rubber gasket (205), thereby achieving gas sealing.

8. The gas-filled coupling terminal according to claim 1, wherein The hollow-core fiber V-groove fixture (202) is provided with a sealing groove (206) for accommodating an O-ring; the sealing groove (206) is coaxial with the hollow-core fiber V-groove fixture (202).

9. The gas-filled coupling terminal according to claim 1 or 8, characterized in that The coupling terminal gas chamber cooling and circulating assembly and the hollow-core fiber fixing assembly are sealed by an O-ring accommodated in the sealing groove (206).

10. The gas-filled coupling terminal according to claim 1, characterized in that, The coupling window mirror (310) is fixed to the gas chamber body (309) by the fixed mirror cover (312), the sealing washer (313) and fastening screws.

11. The gas-filled coupling terminal according to claim 1, wherein, A gas inlet / outlet passage (311) is provided on the side of the gas chamber body (309), and the gas inlet / outlet passage realizes the filling of special gas inside the gas chamber body, the air pressure control and the discharge of special gas through the gas distribution platform (8).

12. The gas-filled coupling terminal according to claim 1, wherein The outer surfaces of the gas-filled coupling terminals are all passivated.

13. The gas-filled coupling terminal according to claim 1, characterized in that, The material of the hollow-core fiber fixing assembly is selected from copper alloy, and the material of the coupling terminal gas chamber cooling and circulating assembly is stainless steel.

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