Laser transmission optical cable based on hollow-core anti-resonance optical fiber

Abstract

A laser transmission optical cable based on a hollow-core anti-resonance optical fiber is suitable for flexible transmission of ultrafast laser, and comprises an input laser beam, and a first optical window, a first air chamber, a first water chamber, a hollow-core capillary optical fiber, a hollow-core anti-resonance optical fiber, a second water chamber, a second air chamber and a second optical window which are sequentially arranged along the beam transmission direction, the hollow-core capillary optical fiber and the hollow-core anti-resonance optical fiber are glued to form a nested structure, and the ratio of the diameter of a cladding capillary of the hollow-core anti-resonance optical fiber to the diameter of a fiber core of the hollow-core anti-resonance optical fiber is 0.63-0.68. The hollow-core anti-resonance optical fiber has high single-mode purity, the problem that a laser mode is coupled to a high-order mode due to mechanical disturbance such as optical fiber bending and twisting can be solved, the hollow-core anti-resonance optical fiber has higher adaptability in a complex processing environment, the laser processing efficiency and stability are improved, and the optical fiber is suitable for large-scale production. And meanwhile, the influence of a heat effect under high power and a nonlinear effect caused by air in an ultrafast laser transmission process are considered.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber technology and laser processing, and in particular to a laser transmission optical cable based on hollow-core anti-resonant optical fiber suitable for ultrafast laser flexible transmission and laser processing. Background Art

[0002] Hollow-core anti-resonant fiber (HC-ARF) is the best choice for optical fiber transmission. Because light propagates in the hollow core, it can control dispersion and nonlinear effects and maintain high quality of laser. However, hollow-core anti-resonant fiber also faces challenges in practical applications, especially in laser processing: Mechanical disturbance: During laser processing, the movement of the hollow-core fiber will change its bending radius and generate stress, causing the beam mode to change from the fundamental mode to the higher-order mode, affecting the processing quality, especially under mechanical disturbances such as bending and torsion, which makes mode coupling more likely to occur.

[0003] Thermal effect: When high-power laser enters the optical fiber, heat accumulation will form at the incident end, causing the optical fiber to deform and affecting the coupling efficiency.

[0004] Nonlinear effects: The high peak power of ultrashort pulse lasers can induce nonlinear effects such as self-phase modulation, Raman effect, and self-focusing, which can change the pulse width, central wavelength, and shape of the pulse, thus affecting the processing effect.

[0005] Research shows that although some work has been done to address nonlinear and thermal effects, the problem of significantly increased coupling losses under mechanical disturbances has not been fully addressed. At the same time, further optimization is still needed to balance low-loss, high-bandwidth transmission and address the challenges of mode coupling caused by mechanical disturbances.

[0006] Patent document CN107621677A discloses a high-power ultrashort pulse flexible transmission system based on hollow-core antiresonant fiber, which transmits light by coupling it into the hollow-core antiresonant fiber, with high coupling efficiency, and light propagates in the fiber core, and the fiber core can be filled with inert gas through the fiber connector, without the influence of material absorption and nonlinear effects, and the hollow-core antiresonant fiber has low loss and wide transmission bandwidth, and the system can also fill the hollow-core antiresonant fiber with gas through the fiber connector, and the fiber connector can also water-cool the hollow-core antiresonant fiber. Although this patented technology solves the problem that nonlinearity and transmission limitation are easily generated in the transmission of high-power ultrashort pulses. However, external factors such as manual operation and air disturbance will affect the single-mode characteristics, generate some random and uncontrollable high-order modes, and then may cause problems such as mode instability, beam quality degradation, and mode crosstalk. Therefore, the transmission system has extremely high environmental requirements, and the use scenario is greatly limited, such as laser processing, and this transmission instability may lead to a decline in processing quality, which cannot meet the needs of high-precision processing, limiting its wide promotion in industrial applications. Summary of the invention

[0007] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a laser transmission optical cable based on hollow-core antiresonant optical fiber, which, while taking into account the influence of thermal effects under high power and the nonlinear effects caused by air during ultrafast laser transmission, solves the problem in the prior art that, during ultrafast laser transmission processing, the mode is coupled to a higher-order mode due to mechanical disturbances such as bending and torsion of the hollow-core optical fiber, which limits its application.

[0008] The technical solution of the present invention is as follows: A laser transmission optical cable based on hollow-core anti-resonant optical fiber, characterized in that it includes an input laser beam, and a first optical window, a first air chamber, a first water chamber, a hollow-core capillary optical fiber, a hollow-core anti-resonant optical fiber, a second water chamber, a second air chamber, and a second optical window arranged in sequence along the beam transmission direction; wherein the first optical window is sealed and connected to the first air chamber, the first air chamber and the first water chamber are both cavity structures, and are internally connected, forming a mirror-symmetrical structure with the second water chamber, the second air chamber, and the second optical window, the hollow-core capillary optical fiber is glued to the hollow-core anti-resonant optical fiber to form a nested structure, and the hollow-core anti-resonant optical fiber is fixedly arranged in a closed space constructed by the first optical window, the first air chamber, the first water chamber, the second water chamber, the second air chamber, and the second optical window, and the ratio of the capillary diameter d1 of the hollow-core anti-resonant optical fiber cladding to the core diameter D1 of the hollow-core anti-resonant optical fiber is 0.63-0.68.

[0009] Preferably, the first gas chamber is filled with an inert gas and is provided with a switchable first gas interface; the second gas chamber is filled with an inert gas and is provided with a switchable second gas interface; the first gas interface and the second gas interface are respectively connected to a vacuum pump for filling and discharging the inert gas in the gas chamber and regulating and controlling the air pressure.

[0010] Preferably, the inert gas includes helium, neon, argon, krypton, and xenon monatomic gases, which reduce the influence of air on laser transmission and improve transmission efficiency.

[0011] Preferably, both sides of the window plates of the first optical window and the second optical window are coated with anti-reflection films corresponding to the output laser wavelength of the light source.

[0012] Preferably, the hollow-core antiresonant optical fiber has high single-mode purity.

[0013] Preferably, the first water chamber and the second water chamber are both made of materials with good thermal conductivity and are provided with at least one cold water interface, and the first water chamber and the second water chamber are provided with a central through groove for placing the input end and the output end of the hollow-core antiresonant optical fiber.

[0014] Preferably, after the optical fiber is fixed, the end cross-sections of the central through grooves of the first water chamber and the second water chamber are filled with a gelatinous substance for vacuum sealing.

[0015] Preferably, the cold water interface is connected to an external water chiller for water injection and drainage.

[0016] Preferably, the outermost layer of the hollow-core antiresonant optical fiber is composed of a layer of fused silica glass tube, and a plurality of silica capillaries are evenly inscribed and distributed on the inner surface of the glass tube to form a hollow-core structure.

[0017] Preferably, the hollow-core anti-resonant optical fiber is also equipped with a metal armor cable for wrapping, which can enhance the mechanical strength of the optical fiber, enable the optical fiber to withstand external pressure, and is not easily worn.

[0018] Preferably, the first optical window and the second optical window both include a window piece and a sealing structure to jointly achieve internal sealing of the entire laser transmission optical cable; a sealing structure is provided between the first air chamber and the first water chamber, and between the second air chamber and the second water chamber.

[0019] Compared with the prior art, the present invention has the following beneficial effects: Hollow-core anti-resonant optical fiber is used, and the ratio of the capillary diameter d1 to the core diameter D1 is close to 0.68, which achieves phase matching between the core high-order mode and the fundamental mode leaked into the capillary, resulting in extremely high loss of the high-order mode, thereby ensuring high single-mode transmission of the laser beam. The anti-resonance effect is used to confine the laser to the hollow structure of the core for transmission, which is particularly suitable for the flexible transmission requirements of ultrafast lasers. This optical cable is designed for continuous use in harsh environments. Even when undergoing complex bends, it can effectively suppress the generation of high-order modes and ensure stable transmission of the laser in a high-quality fundamental mode form. Hollow-core anti-resonant optical fiber has high single-mode purity and can maintain the laser beam propagating in the fundamental mode during laser transmission, effectively suppressing the generation of high-order modes, making the optical cable more adaptable in complex processing environments and significantly improving the efficiency and stability of laser processing. Filling the hollow-core antiresonant optical fiber with gas and water-cooling the hollow-core antiresonant optical fiber can not only weaken the nonlinear effect caused by air during ultrafast laser transmission, but also reduce the impact of thermal effects under high power. This has broad application prospects in many fields such as industry, medical care, and communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the overall structure of a laser transmission optical cable based on hollow-core anti-resonant optical fiber provided by the present invention; Figure 2 Schematic diagram of the cross-sectional structure of a hollow-core antiresonant optical fiber.

[0022] Figure 3 A schematic diagram of the internal structure of the input end of a laser transmission optical cable based on a hollow core anti-resonant optical fiber provided by the present invention; Figure 4 A schematic diagram of the tail structure of the input end of a laser transmission optical cable based on a hollow core anti-resonant optical fiber provided by the present invention.

[0023] Figure 5 The mode distribution of the output light beam of the hollow-core antiresonant fiber with a structure of d1 / D1≈0.68 when stationary and swinging, respectively, recorded every 20 s within 1 min; (a1-a4): the mode distribution of the output of the hollow-core antiresonant fiber with d1 / D1≈0.68 when stationary; (b1-b4): the mode distribution of the output of the hollow-core antiresonant fiber with d1 / D1≈0.68 when swinging.

[0024] Figure 6 The mode distribution of the output light beam of a hollow-core antiresonant fiber with a structure of d1 / D1≈0.5 when stationary and swinging, respectively, recorded every 20 s within 1 min; (a1-a4): the mode distribution of the output of a hollow-core antiresonant fiber with d1 / D1≈0.5 when stationary; (b1-b4): the mode distribution of the output of a hollow-core antiresonant fiber with d1 / D1≈0.5 when swinging.

[0025] Wherein, the accompanying drawings are marked as follows: 1: input laser beam; 2: first optical window; 21: metal housing; 22: first rubber ring; 23: window piece; 24: second rubber ring; 3: first air chamber; 31: first gas interface; 4: first water chamber; 41: first cold water interface; 42: second cold water interface; 43: third rubber ring; 44: insert; 45: metal armor cable; 5: Hollow core capillary fiber; 6: hollow core antiresonant optical fiber; 7: water chiller; 8: second water chamber; 81: third cold water interface; 82: fourth cold water interface; 9: second air chamber; 91: second gas interface; 10: second optical window; 11: gas circuit control panel; 12: vacuum pump; 13: output laser beam. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be noted that the application scope of the laser transmission optical cable provided by the present invention includes but is not limited to laser processing. In order to simplify the description, the subsequent embodiments are described by using the laser transmission optical cable provided by the present invention for laser processing as an example.

[0028] Figure 1 FIG. 1 is a schematic diagram of the overall structure of an embodiment of a laser transmission optical cable based on a hollow core anti-resonant optical fiber according to the present invention. Figure 1 As shown, a laser transmission optical cable based on hollow core anti-resonant optical fiber includes the following components in sequence along the laser transmission path: The input laser beam 1, as a laser source, provides initial laser energy.

[0029] The first optical window 2 protects the inside of the optical cable from the external environment while allowing the laser to pass efficiently. It consists of a window and a sealing structure. Both sides of the window are coated with an anti-reflection film that matches the laser wavelength (such as 1064 nm) to improve the laser transmittance.

[0030] The first air chamber 3 is filled with an inert gas (such as argon) to reduce the influence of air on laser transmission. A switchable gas interface is provided to facilitate gas filling, exhausting and gas pressure adjustment.

[0031] The first water chamber 4 is made of a material with good thermal conductivity (such as copper) and is provided with a cold water interface connected to a water chiller for cooling to reduce the thermal effect during laser transmission.

[0032] The hollow-core capillary fiber 5 serves as a transition portion before the laser enters the hollow-core anti-resonance fiber, ensuring that the laser can be accurately coupled into the hollow-core anti-resonance fiber.

[0033] Hollow core anti-resonant fiber 6 uses the anti-resonance principle to achieve stable transmission of laser in the air core. High single-mode purity ensures that the laser is transmitted in the fundamental mode, avoiding the generation of high-order modes, thereby improving the transmission stability and beam quality. The interior of the optical fiber needs to be evacuated to eliminate the nonlinear effect caused by air.

[0034] The second water chamber 8, the second air chamber 9 and the second optical window 10 have the same functions as the first water chamber, the first air chamber and the first optical window, but are located at the end of the laser transmission path to ensure the stability and quality of the laser before output.

[0035] The output laser beam 13 is a laser beam output from the optical cable and is used for applications such as laser processing.

[0036] The hollow-core antiresonant optical fiber has high single-mode purity and is fixed in a closed space constructed by the first optical window, the first air chamber, the first water chamber, the second water chamber, the second air chamber, and the second optical window; the high single-mode purity means that when the optical fiber transmits laser, it can maintain the laser beam propagating in the fundamental mode (i.e., single mode) without generating or generating very little high-order mode, making it more adaptable in complex processing environments and improving the efficiency and stability of laser processing.

[0037] The hollow-core antiresonant optical fiber satisfies: the ratio of the cladding capillary diameter d1 to the core diameter D1 is close to 0.68. Under this condition, the core high-order mode and the fundamental mode leaking into the capillary are phase-matched, resulting in very high loss.

[0038] The principle of anti-resonance is that when the wavelength of light is the resonant wavelength, the binding force of the cladding wall on the light is weakened, and the light leaks out of the cladding. When the wavelength of light is the anti-resonant wavelength, the binding ability of the cladding wall on the light is enhanced, and the light is bound to the air core, thereby achieving the purpose of light transmission in the core.

[0039] It should be noted that when using the laser transmission cable provided by the present invention for laser transmission, the interior of the hollow-core anti-resonant optical fiber 6 needs to be evacuated to ensure that the laser transmitted in the hollow-core anti-resonant optical fiber 6 is in a vacuum state to avoid the occurrence of nonlinear effects caused by air.

[0040] In the actual work process, Figure 1 As shown, the input laser beam 1 is an ultrafast laser of 1064 nm, which enters from the first optical window 2 by focusing coupling, with its focus located in the hollow core of the input end of the hollow-core capillary fiber 5, passes through the first air chamber 3 and enters the first water chamber 4, and after anti-resonance transmission of the hollow-core fiber for a certain distance, passes through the second water chamber 8 and enters the second air chamber 9, and the output laser beam 13 is transmitted from the second optical window 10 to the laser processing application end.

[0041] The first optical window 2 and the second optical window 10 are used as protective windows, and are respectively located on one side of the input end and the output end of the hollow-core capillary optical fiber 5, so as to reduce the influence of the environment and temperature on the laser transmission; The first optical window 2 and the second optical window 10 are both composed of a window sheet and a sealing structure, and both sides of the window sheet are coated with a 1064 nm wavelength anti-reflection film to ensure high transmittance of the laser while maintaining the sealing performance; The first water chamber 4 and the second water chamber 8 are both made of materials with good thermal conductivity. Specifically, in this embodiment, the water chamber material is copper; The first water chamber 4 is provided with a first cold water interface 41 and a second cold water interface 42, and the second water chamber 8 is provided with a third cold water interface 81 and a fourth cold water interface 82, which are connected to the water chiller 7 for water injection and drainage to improve power stability and pointing stability; The first air chamber 3 and the second air chamber 9 are respectively provided with a switchable first gas interface 31 and a second gas interface 91, which are connected to a vacuum pump 12 through a gas circuit control panel 11, and are used for filling and discharging the inert gas in the air chamber and regulating and controlling the air pressure; wherein, in this embodiment, the gas filled in the first air chamber 3 and the second air chamber 9 is argon, including but not limited to argon.

[0042] It should be noted that the gas circuit control panel 11 includes a plurality of switch interfaces. Figure 1 The gas circuit control panel 11 in the figure only indicates a part of the connection, not all of it. Figure 1 As shown, the first gas interface 31, the second gas interface 91 and the air pump 12 are connected respectively, and various gas cylinders, barometers and air environments can also be connected.

[0043] The process of vacuuming is as follows: before performing the gas filling and deflation operations, first check the air tightness. Specifically, open the switch connecting the gas circuit control panel 11 to the vacuum pump 12 and the first gas interface 31 and the second gas interface 91, and ensure that the interface between the gas circuit control panel 11 and the air and gas cylinder remains closed. Further, start the vacuum pump 12 to completely extract the gas in the optical fiber, then turn off the vacuum pump 12 and related switches, and take readings through the barometer. Wait for one hour. If there is no obvious change in the barometer reading, it means that the device is airtight under vacuum. Further, open the switch connected to the gas cylinder, fill 3-4 bar of argon into the optical fiber, and then close the relevant interfaces. Wait for one hour. If the barometer reading is stable, the air tightness is good. In subsequent operations, if vacuuming is required, open the interface connected to the air, slowly release the gas, close it and then open the interface connected to the vacuum pump 12, start the vacuum pump 12 to a vacuum state, and then close the vacuum pump 12 and related interfaces; if inflation is required, open the interface connected to the gas cylinder, slowly inflate to the target air pressure, and finally close all switch interfaces.

[0044] In addition, considering that when hollow-core antiresonant fiber is introduced into industry, a key point is that it must be used in a more harsh environment, resulting in the fiber being affected by the external environment during transmission to excite the higher-order modes within the fiber, which reduces the stability of the transmission and the beam quality. In order to transmit higher pulse energy and couple it reliably into the fiber, a larger core is required; however, a larger core also allows for smaller separation between higher-order modes within the fiber, resulting in instability. In order to still maintain high beam quality, the present invention maintains quasi-fundamental mode characteristic transmission by adopting a high single-mode purity hollow-core antiresonant fiber.

[0045] Specifically, in this embodiment, if Figure 2 As shown, the hollow core antiresonant fiber 6 is 3 m long and consists of 6 capillaries forming an annular cladding, the average capillary diameter d1 is 19.88 μm, the average core diameter D1 is 29.2 μm, and d1 / D1≈0.68, which is the optimal theoretical ratio. This optical fiber can effectively suppress the generation of high-order modes and is used to achieve high-quality fundamental mode transmission.

[0046] Figure 3 Schematic diagram of the internal structure of the input end of the laser transmission optical cable based on hollow core anti-resonant optical fiber provided by the present invention, such as Figure 3 As shown, the first optical window 2 includes a metal shell 21 , a first rubber ring 22 , a window sheet 23 , and a second rubber ring 24 .

[0047] The sealing structure of the first optical window 2 is a ring-shaped rubber vacuum sealing ring; the window sheet 23 is sandwiched between the first rubber ring 22 and the second rubber ring 24 to ensure airtightness there; The outer ring of the first optical window 2 is provided with 6 M2.5 screw holes; further, the first optical window 2 is connected to the first air chamber 3 by 6 M2.5 screws; The first air chamber 3 is provided with 6 and 8 M2.5 screw holes at both ends respectively; The inner circle of one side of the first water chamber 4 is provided with 8 M2.5 screw holes, and the outer circle is provided with 8 M4 screw holes; further, the first air chamber 3 is connected to the first water chamber 4 by 8 M2.5 screws; The first water chamber 4 is provided with a groove for placing a rubber ring, and the air tightness of the connection between the first air chamber 3 and the first water chamber 4 is ensured by placing a third rubber ring 43 in the groove; The center of the first water chamber 4 is also provided with a through cylindrical groove, and the metal ferrule 44 with matched aperture and the hollow-core capillary optical fiber 5 are provided in the groove; wherein the hollow-core anti-resonance optical fiber 6 is fixed in the hollow-core capillary optical fiber 5; The outer diameter of the metal insert 44 is equal to the inner diameter of the center hole of the first water chamber 4; The outer diameter of the hollow capillary optical fiber 5 is equal to the inner diameter of the metal ferrule 44; The outer diameter of the hollow-core antiresonant optical fiber 6 is equal to the inner diameter of the hollow-core capillary optical fiber 5; The hollow-core capillary optical fiber 5 , the hollow-core anti-resonant optical fiber 6 , the metal ferrule 44 and the first water chamber 4 are connected by vacuum glue, and the present invention does not make any specific limitation on the specific implementation means of the sealing process.

[0048] A cylindrical shell is provided at the end of the first water chamber 4 for connecting a metal armor cable 45 .

[0049] In this embodiment, the hollow-core antiresonant optical fiber can be bent, and the metal armor cable 45 set provides additional physical protection to prevent the optical fiber from being damaged by external impact and stretching during installation and use, and can also effectively resist the influence of environmental factors such as moisture, chemical corrosion, etc.

[0050] It should be noted that, in this embodiment, Figure 1 As shown, in order to further ensure the sealed environment of the laser transmission optical cable, a setting symmetrical to the input end is added to the output end of the laser transmission optical cable, and the output end is not described in detail here.

[0051] In order to illustrate that the laser transmission optical cable provided by the present invention can be used in harsh environments, specifically, in this embodiment, the metal armor cable 45 is swung to create a working state in which the optical fiber shakes violently.

[0052] Figure 5The mode distribution of the output beam of the hollow core antiresonant fiber with a structure of d1 / D1≈0.68 recorded every 20 s within 1 min when it is stationary and swinging; (a1-a4): the mode distribution of the output of the hollow core antiresonant fiber with d1 / D1≈0.68 when it is stationary; (b1-b4): the mode distribution of the output of the hollow core antiresonant fiber with d1 / D1≈0.68 when it is swinging. The test results show that the single-mode characteristics can be guaranteed regardless of whether the antiresonant hollow core fiber is stationary or swinging.

[0053] As an optional comparative embodiment, a common hollow-core antiresonant optical fiber is replaced. Specifically, the hollow-core antiresonant optical fiber is 3 m long, and is composed of 7 capillaries forming an annular cladding, the average capillary diameter d1 is 16.55 μm, the average core diameter D1 is 33 μm, and d1 / D1≈0.5.

[0054] Figure 6 The mode distribution of the output beam of the hollow-core antiresonant fiber with a structure of d1 / D1≈0.5 recorded every 20 s within 1 min when it is stationary and swinging; (a1-a4): the mode distribution of the output of the hollow-core antiresonant fiber with d1 / D1≈0.5 when it is stationary; (b1-b4): the mode distribution of the output of the hollow-core antiresonant fiber with d1 / D1≈0.5 when it is swinging. The test results show that the antiresonant hollow-core fiber used can maintain a single mode when it is stationary, and there are high-order modes in the swinging state, which further illustrates the impact of the fiber when it is in a violent shaking state.

[0055] The core of the laser transmission optical cable provided by the present invention is a hollow-core anti-resonant optical fiber. The main difference from the traditional solid-core optical fiber is that the anti-resonance effect is used to limit the transmission of the laser in the hollow core, which is suitable for the flexible transmission of ultrafast lasers. The optical cable takes into account continuous use in demanding environments. Even after bending, it can effectively suppress the generation of high-order modes and ensure high-quality fundamental mode transmission. In addition, the optical cable is also improved in structure, the hollow-core anti-resonant optical fiber is filled with gas, and the hollow-core anti-resonant optical fiber is water-cooled, which can not only weaken the nonlinear effect caused by air during ultrafast laser transmission, but also reduce the impact of thermal effects under high power, which has broad application prospects in many fields such as industry, medical treatment, and communications.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A laser transmission cable based on hollow core anti-resonant optical fiber, suitable for flexible transmission of ultrafast laser, characterized in that: It includes an input laser beam, and a first optical window, a first air chamber, a first water chamber, a hollow-core capillary fiber, a hollow-core anti-resonance fiber, a second water chamber, a second air chamber, and a second optical window arranged in sequence along the beam transmission direction; wherein the first optical window is sealed and connected to the first air chamber, the first air chamber and the first water chamber are both cavity structures, and are internally interconnected, forming a mirror-symmetrical structure with the second water chamber, the second air chamber, and the second optical window, the hollow-core capillary fiber and the hollow-core anti-resonance fiber are glued to form a nested structure, and the hollow-core anti-resonance fiber is fixed in a closed space constructed by the first optical window, the first air chamber, the first water chamber, the second water chamber, the second air chamber, and the second optical window, and the ratio of the cladding capillary diameter d1 of the hollow-core anti-resonance fiber to the core diameter D1 of the hollow-core anti-resonance fiber is 0.63-0.

68.

2. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 1, characterized in that: The first gas chamber is filled with an inert gas and is provided with a switchable first gas interface; the second gas chamber is filled with an inert gas and is provided with a switchable second gas interface; the first gas interface and the second gas interface are respectively connected to a vacuum pump for filling and discharging the inert gas in the gas chamber and regulating and controlling the gas pressure.

3. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 2, characterized in that: The inert gas includes helium, neon, argon, krypton, and xenon monatomic gases.

4. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 1, characterized in that: Both sides of the window plates of the first optical window and the second optical window are coated with anti-reflection films corresponding to the wavelength of the output laser beam.

5. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 1, characterized in that: The hollow core anti-resonant optical fiber has high single-mode purity.

6. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 1, characterized in that: The first water chamber and the second water chamber are both made of materials with good thermal conductivity and are provided with at least one cold water interface. The first water chamber and the second water chamber are provided with a centrally penetrating groove for placing the input end and the output end of the hollow-core antiresonant optical fiber.

7. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 6, characterized in that: After the optical fiber is fixedly installed, the end cross-sections of the central through grooves of the first water chamber and the second water chamber are filled with a gelatinous substance for vacuum sealing.

8. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 6, characterized in that: The cold water interface is externally connected to a water chiller for water injection and drainage.

9. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to any one of claims 1 to 8, characterized in that: The outermost layer of the hollow-core anti-resonance optical fiber is composed of a layer of fused silica glass tube, and six silica capillaries are evenly distributed inscribed on the inner surface of the glass tube to form a hollow-core structure.

10. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 9, characterized in that: The hollow core anti-resonance optical fiber is also equipped with a metal armor cable for wrapping.

11. The laser transmission optical cable based on hollow core anti-resonant optical fiber according to claim 1, characterized in that: The first optical window and the second optical window both include a window piece and a sealing structure to jointly achieve internal sealing of the entire laser transmission optical cable; a sealing structure is provided between the first air chamber and the first water chamber, and between the second air chamber and the second water chamber.

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