Medical mid-infrared hollow core fiber transmission device

Abstract

The application relates to a medical mid-infrared hollow-core optical fiber transmission device, which comprises an optical fiber body, an end cap and a connecting structure, the optical fiber body has an output end, the end cap has a connecting surface for being connected with the output end of the optical fiber body, the end cap is made of a biocompatible inorganic non-metallic material, the infrared absorption cutoff wavelength of the end cap is greater than 6 mu m, and the transmittance in the 2-6 mu m wave band is greater than or equal to 50%, the connecting structure comprises a glass sealing element, the glass sealing element is arranged at the connecting surface of the output end of the optical fiber body and the end cap, the glass sealing element and the outer peripheral surface of the output end of the optical fiber body form a ring-shaped contact interface, and the glass sealing element is fused between the output end of the optical fiber body and the connecting surface of the end cap, so that the optical fiber body and the end cap are in sealed connection. The application meets the diversified requirements of different operation scenes on the mid-infrared laser wave band, the material itself is non-toxic and stable, and the safety of the interventional laser operation is ensured.

Description

Technical Field

[0001] This application relates to the field of optical fiber manufacturing technology, and in particular to a medical mid-infrared hollow optical fiber transmission device. Background Technology

[0002] Hollow-core optical fibers offer flexible structural designs, allowing for dimensional adjustments to accommodate different diameters and curvatures within the human body (such as arteries and the urethra), meeting the needs of typical applications like arterial plaque ablation and laser lithotripsy. The end cap, a core component of medical hollow-core optical fibers, directly determines the fiber's laser transmission efficiency, energy tolerance threshold, and the safety and stability of its clinical use. Firstly, the end cap reduces the power density at the output end face of the hollow-core fiber, preventing damage when transmitting high-peak-power femtosecond lasers. Furthermore, the specially designed shape of the end cap's tail also helps to collimate and focus the output beam. More importantly, the connection structure between the end cap and the optical fiber must provide a good physical seal to prevent the hollow-core fiber from being invaded by blood, tissue fluid, or other biological fluids within the human body.

[0003] However, reliable connection between hollow fiber and end cap has always been a technical challenge. Hollow fiber has a microstructure that is extremely sensitive to thermal and mechanical stress. If conventional fusion splicing methods are used, the heat or stress generated during the process can easily cause the microstructure of the hollow fiber to collapse or deform, damaging the fiber's transmission performance, leading to a surge in transmission loss and significant heat accumulation. This can easily cause the end cap to melt, potentially burning human tissue. To avoid damaging the hollow fiber's microstructure, the connection strength of the end cap must be sacrificed, which is prone to detachment in the complex environment of the body. A detached end cap can cause vascular embolism, leading to tissue infarction and directly threatening the patient's life. Furthermore, current research on hollow fiber and end cap fusion splicing focuses only on the near-infrared band within 2μm, with research in the mid-infrared band remaining unexplored. The properties of the end cap materials suitable for this band differ significantly from those of quartz, further increasing the difficulty of hollow fiber and end cap fusion splicing and severely restricting the medical applications of hollow fiber in the mid-infrared band. Summary of the Invention

[0004] This application provides a medical mid-infrared hollow fiber transmission device, which can solve the problem of poor connection reliability when connecting hollow fiber to end cap in related technologies.

[0005] In a first aspect, embodiments of this application provide a medical mid-infrared hollow fiber optic transmission device, comprising: an optical fiber body, an end cap, and a connecting structure. The optical fiber body has an output end; the end cap has a connecting surface that mates with the output end of the optical fiber body, the end cap is made of a biocompatible inorganic non-metallic material, the infrared absorption cutoff wavelength of the end cap is greater than 6 μm, and the transmittance in the 2-6 μm band is ≥50%; the connecting structure includes a glass seal, the glass seal is disposed at the connecting surface between the output end of the optical fiber body and the end cap, wherein the glass seal and the outer peripheral surface of the output end of the optical fiber body form an annular contact interface, and the glass seal is fused between the output end of the optical fiber body and the connecting surface of the end cap, so that the optical fiber body and the end cap form a sealed connection.

[0006] In one embodiment, the end cap material includes at least one of SiO2, Al2O3, YAG, Si, Y2O3, and YSZ.

[0007] In one embodiment, when the end cap is used in the 2-3μm band, the end cap material is SiO2, Al2O3, YAG, Si, Y2O3 or YSZ; When the end cap is used in the 3-5μm band, the end cap material is Al2O3, YAG, Si, Y2O3 or YSZ; When the end cap is used in the 5-6μm band, the end cap material is Si, Y2O3 or YSZ.

[0008] In one embodiment, the axial length of the end cap is ≤10mm, the maximum diameter is ≤2mm, and both the connecting surface and the output end of the end cap are planar with a surface roughness of ≤1nm.

[0009] In one embodiment, the output end surface of the end cap is coated with an antireflection film, the antireflection film comprising a first film layer and a second film layer sequentially stacked on the output end surface, the first film layer being located on the side of the second film layer away from the end cap.

[0010] In one embodiment, the material of the first film layer is SiO2, Al2O3, MgO, Y2O3, ZrO2 or diamond; The material of the second film layer is SiO2, Al2O3, MgO, Y2O3, ZrO2 or diamond; The refractive index of the first film layer is less than that of the second film layer; In the same antireflective membrane, the first membrane layer and the second membrane layer are made of different materials.

[0011] In one embodiment, the glass seal is made of borosilicate glass with a B2O3 content ≥10%; The inner diameter of the glass seal is 10-20 μm larger than the outer diameter of the cladding of the optical fiber body, and the outer diameter of the glass seal is ≤2 mm.

[0012] In one embodiment, the melting point of the glass seal is lower than the melting point of the end cap; The melting point of the glass seal is lower than that of the optical fiber body.

[0013] In one embodiment, the glass seal is annular in shape and is fitted around the outer periphery of the output end of the optical fiber body; The connection structure also includes a sealing medium that fills the gap between the glass seal and the optical fiber body.

[0014] The beneficial effects of the technical solutions provided in this application include: This application provides a medical mid-infrared hollow fiber optic transmission device. Because the end cap is made of a biocompatible inorganic non-metallic material with an infrared absorption cutoff wavelength greater than 6μm and a transmittance of ≥50% in the 2-6μm band, the intrinsic absorption edge of the material is located outside the working band, which reduces the intrinsic absorption of photons by lattice vibrations. This allows the mid-infrared laser to maintain a high energy transmittance when passing through the end cap. This material characteristic enables the device to adapt to multiple specific working wavelengths in the 2-6μm range, meeting the diverse needs of different surgical scenarios for the mid-infrared laser band. At the same time, the material itself is non-toxic and stable, ensuring the safety of performing interventional laser surgery.

[0015] The glass seal in the connection structure is fused between the optical fiber body and the end cap. The molten glass fills the microscopic gaps at the interface and forms a dense physical sealing layer after cooling, blocking the penetration path of biological fluid into the optical fiber. The glass seal forms an annular contact interface with the outer peripheral surface of the output end of the optical fiber body, so that the connection force is concentrated at the outer periphery of the optical fiber. This prevents the connection material from covering or flowing into the microstructural pores in the center of the optical fiber and reduces the conduction of fusion heat to the fiber core region. Thus, the integrity of the original microstructure of the hollow optical fiber is maintained while achieving a sealed connection. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure provided for an embodiment of this application; Figure 2This is a schematic diagram of the end cap structure provided in an embodiment of this application; Figure 3 This is a schematic diagram of an antireflection membrane provided in an embodiment of this application.

[0018] In the figure: 1. Optical fiber body; 2. End cap; 3. Antireflective coating; 31. First coating layer; 32. Second coating layer; 4. Glass seal; 5. Sealing medium. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] This application provides a medical mid-infrared hollow fiber transmission device, which can solve the problem of poor connection reliability when connecting hollow fiber to end cap in related technologies.

[0021] See Figures 1 to 3 This application provides a medical mid-infrared hollow fiber optic transmission device, which includes: an optical fiber body 1, an end cap 2, and a connection structure. The optical fiber body 1 has an output end; the end cap 2 has a connection surface that mates with the output end of the optical fiber body 1. The end cap 2 is made of a biocompatible inorganic non-metallic material, and the infrared absorption cutoff wavelength of the end cap 2 is greater than 6μm, and the transmittance in the 2-6μm band is ≥50%. The connection structure includes a glass seal 4, which is disposed at the connection surface between the output end of the optical fiber body 1 and the end cap 2. The glass seal 4 forms an annular contact interface with the outer peripheral surface of the output end of the optical fiber body 1. The glass seal 4 is fused between the output end of the optical fiber body 1 and the connection surface of the end cap 2 to form a sealed connection between the optical fiber body 1 and the end cap 2.

[0022] In this application, since the end cap 2 is made of an inorganic non-metallic material with an infrared absorption cutoff wavelength greater than 6μm and a transmittance of ≥50% in the 2-6μm band, the intrinsic absorption edge of the material is located outside the working band, which reduces the intrinsic absorption of photons by lattice vibrations. This allows the mid-infrared laser to maintain a high energy transmittance when passing through the end cap 2. This material characteristic enables the device to be adapted to multiple specific working wavelengths in the 2-6μm range, meeting the diverse needs of different surgical scenarios for the mid-infrared laser band. At the same time, the material itself is non-toxic and stable, ensuring the safety of performing interventional laser surgery. The glass seal 4 in the connection structure is fused between the optical fiber body 1 and the end cap 2. The molten glass fills the microscopic gaps at the interface and forms a dense physical sealing layer after cooling, blocking the penetration path of biological liquid into the optical fiber. The glass seal 4 forms an annular contact interface with the outer peripheral surface of the output end of the optical fiber body 1, so that the connection force is concentrated on the outer periphery of the optical fiber, avoiding the connection material from covering or flowing into the microstructure pores in the center of the optical fiber, reducing the conduction of fusion heat to the fiber core area, thereby maintaining the integrity of the original microstructure of the optical fiber body 1 while achieving a sealed connection.

[0023] In this embodiment, the glass seal 4 forms an annular contact interface with the outer peripheral surface of the output end of the optical fiber body 1. Therefore, the glass seal 4 is configured in an annular structure and fitted onto the outer periphery of the output end of the optical fiber body 1. The inner diameter of this annular structure is 10-20 μm larger than the outer diameter of the cladding of the optical fiber body 1, the outer diameter does not exceed 2 mm, and the length is 3-5 mm, so that the glass seal 4 and the outer peripheral surface of the output end of the optical fiber body 1 form an annular contact interface. Furthermore, the connection structure also includes a sealing medium 5, which fills the gap between the glass seal 4 and the optical fiber body 1 to achieve initial fixation.

[0024] In this embodiment, the sealing medium 5 is a sealing silicone grease. The sealing silicone grease fills the gap between the glass seal 4 and the optical fiber body 1, ensuring that the surfaces of the glass seal 4 and the output end of the optical fiber body 1 remain flush, forming a stable support structure. The sealing silicone grease is medical grade, with a temperature resistance of ≥180℃, and can adapt to the temperature environment of subsequent connection processes, preventing medium failure.

[0025] When the optical fiber body 1 and end cap 2 are mated, the glass seal 4 is located between their connection surfaces. The glass seal 4 is made of high borosilicate glass with a B2O3 content ≥10%. Furthermore, the melting point of the glass seal 4 is lower than that of the end cap 2, and the melting point of the glass seal 4 is lower than that of the optical fiber body 1. After being softened by heating, the glass seal 4 adheres tightly to the surfaces of the optical fiber body 1 and end cap 2, filling microscopic gaps and eliminating interface reflection. This structure achieves a high-strength connection and seal between the two, preventing high-temperature damage to core components, while meeting the transmission stability requirements in the mid-infrared band and ensuring the reliability of the device in a fluid environment.

[0026] In this embodiment, a low-melting-point glass encapsulation process is used for the connection between the optical fiber body 1 and the end cap 2. A reliable connection between the crystalline and amorphous materials is achieved through the melting and cooling of the glass seal 4. The glass seal 4 is preferably made of borosilicate material with a melting point ≤1600℃ and a B2O3 content ≥10%, which will not damage the microstructure of the optical fiber body 1 during the softening and melting stage. Heating softens the glass seal 4, filling the connection surface between the output end of the optical fiber body 1 and the end cap 2. The glass flow characteristics are used to fill the microscopic gaps, and after cooling, a solid connection is formed, ensuring a tight interface and reducing optical loss.

[0027] This structure offers excellent sealing. The glass seal 4 forms an annular contact interface with the outer peripheral surface of the output end of the optical fiber body 1, effectively preventing the intrusion of various liquids and gases. The sealing medium 5 fills the gap between the glass seal 4 and the optical fiber body 1, assisting in fixation and buffering stress. The connection strength between the end cap 2 and the optical fiber body 1 is ≥10N, meeting mechanical stability requirements and capable of withstanding axial tensile force and lateral bending force, preventing interface cracking and ensuring the structural integrity of the transmission device under stress.

[0028] Even in complex clinical environments such as high temperature and humidity, and after repeated insertion, removal, and bending during surgery, the end cap 2 will not detach. The melting point of the glass seal 4 is lower than that of the fiber body 1 and the end cap 2, avoiding thermal damage and ensuring the safety of surgical procedures and the transmission stability in the mid-infrared band. This encapsulation method is adapted to the body fluid environment, prevents corrosion of biocompatible materials, maintains long-term reliable optical performance, and meets the standards for durability and safety of medical devices.

[0029] Based on the above embodiments, in this embodiment, the end cap 2 connected to the output end of the optical fiber body 1 is made of a material with high transmittance in the 2-6μm mid-infrared band. The infrared absorption cutoff wavelength of the end cap 2 is greater than 6μm, and the transmittance in the 2-6μm band is ≥50% to ensure effective transmission of laser energy. The selection of the material of the end cap 2 is matched with the application band, and at the same time, it must meet the requirements of high biocompatibility and high melting point to adapt to the medical environment and prevent erosion by body fluids and thermal damage.

[0030] In this embodiment, the end cap 2 is made of a biocompatible inorganic non-metallic material. This material is a safe, non-toxic, and highly stable non-metallic inorganic material selected from materials that can transmit the mid-infrared band. Specifically, it is selected from transparent oxide ceramics or single-crystal materials. The end cap 2 material includes at least one of SiO2, Al2O3, YAG, Si, Y2O3, and YSZ. Compared with conventional mid-infrared high-transmittance materials, the selected material is not easily corroded or dissolved under the acidic or alkaline environment of the human body and the action of biological tissue fluid, and it is non-toxic. It can directly contact the skin, blood, tissues, or organs, meeting the safety requirements for long-term use in the body.

[0031] Specifically, the inorganic non-metallic materials used in end cap 2 include SiO2-quartz glass, Al2O3-sapphire, YAG-yttrium aluminum garnet transparent ceramic, Si-silicon, Y2O3-yttrium oxide transparent ceramic, and YSZ-(8-12) mol% yttrium oxide-doped zirconium oxide transparent ceramic. The various material forms encompass amorphous, single-crystal, and transparent ceramics, corresponding to different infrared absorption characteristics.

[0032] Material selection must match the working wavelength to ensure that the transmittance of end cap 2 is ≥50% in the 2-6μm range, while also meeting biocompatibility requirements to prevent erosion by body fluids.

[0033] When the end cap 2 is used in the 2-3μm wavelength band, the material of the end cap 2 can be SiO2, Al2O3, YAG, Si, Y2O3, or YSZ. The material selection range is relatively wide in this wavelength band. Quartz and oxide ceramics can maintain low absorption loss and have a melting point ≥1800℃, which can withstand high peak power laser without thermal damage, ensuring structural stability and meeting the needs of scenarios such as kidney stone ablation.

[0034] When end cap 2 is used in the 3-5μm wavelength band, the material used for end cap 2 is Al2O3, YAG, Si, Y2O3, or YSZ; when used in the 5-6μm wavelength band, the material used for end cap 2 is Si, Y2O3, or YSZ. As the wavelength band moves towards longer wavelengths, the absorption of some materials increases, thus gradually narrowing the range of selectable materials. All selected materials meet biocompatibility standards, ensuring non-toxicity upon in vivo contact. The axial length of end cap 2 is ≤10mm, and the maximum diameter is ≤2mm, facilitating minimally invasive surgical procedures. The shape of end cap 2 is preferably cylindrical, but it can also be a complex shape composed of multiple cylinders, frustums, etc. One end face of end cap 2 is connected to the fiber body 1, and the other end face is used for laser output. Both the connection surface and the output end of end cap 2 are planar, with a surface roughness ≤1nm, reducing scattering loss.

[0035] Therefore, this application provides various low-loss end-cap 2 material selection schemes for the three wavelength bands of 2-3μm, 3-5μm, and 5-6μm. The end cap 2 is made of transparent oxide ceramic or single-crystal material, with a transmittance of ≥50% and insertion loss ≤3dB for the above three wavelength bands. Different inorganic non-metallic materials have different absorption coefficients in the mid-infrared band. By matching the intrinsic absorption peak of the material with the working wavelength, the risk of thermal effects is reduced. For example, SiO2 or Al2O3 can be selected in the 2-3μm band, while Si or Y2O3 should be selected in the 5-6μm band to ensure that the energy transmission efficiency meets the power requirements of medical lasers and to avoid material overheating affecting transmission stability.

[0036] End cap 2 is compatible with various fiber optic body 1 structures, including single rings, nested rings, nested rings with support, and nested rings with auxiliary units, with 2-4 nesting layers. The output end face of end cap 2 is circular, with an axial length ≤10mm and an output end face diameter ≤2mm, adapting to the medical requirements of various human access routes such as the ureter, aorta, and carotid artery. This size range ensures that end cap 2 can be accommodated within the inner diameter of conventional medical catheters, facilitating entry into the target area within the body through minimally invasive channels. The axial length limitation avoids excessive stress within tortuous blood vessels, preventing end cap 2 from becoming too long and reducing operational flexibility. The circular end face promotes uniform light output, reduces concentrated thermal damage to surrounding tissues, adapts to confined surgical environments, and ensures catheter passage within the body.

[0037] For any end cap 2, its material meets the safety requirements for externally connected medical devices specified in GB / T16886 and satisfies the standards for surgical use. The material must pass cytotoxicity, sensitization, acute systemic toxicity, irritation, and pyrogen tests to ensure long-term stability in body fluid environments and to prevent the generation of biotoxicity. The surface roughness of end cap 2 is ≤1nm, which greatly reduces end-face scattering loss and ensures the stability of laser transmission. The low-roughness surface, combined with the antireflection film 3 on the surface of end cap 2, reduces interface reflection loss, jointly ensuring the safety of surgical operations and the reliability of energy transmission, meeting the standards for durability and safety of medical devices.

[0038] Based on the above embodiments, in this embodiment, to reduce Fresnel reflection at the end face, an antireflection film 3 is coated on the output end surface of the end cap 2. The design of the antireflection film 3 needs to match the refractive index of the end cap 2 material to achieve a high transmission efficiency. Since the refractive index difference between the end cap 2 material and air is significant, direct contact will cause significant reflection loss, resulting in some laser energy being reflected back into the optical fiber or converted into heat, affecting transmission efficiency. The antireflection film 3 buffers the interface abrupt change through a gradient refractive index distribution, reducing the return of light energy at the interface and optimizing the optical path transmission efficiency. The film structure design follows the 1 / 4 wavelength matching principle, optimized for specific wavelengths of 2-6μm, causing destructive interference of reflected light at the film interface. The wave characteristics of light are used to cancel out the reflection component, thereby improving transmittance. After coating, the transmittance of the end cap 2 to the above three bands increases to ≥95%, and the overall insertion loss decreases to ≤1.5dB. This can significantly reduce laser energy loss and heat accumulation, prevent the end cap 2 from heating up due to excessive energy absorption, avoid thermal damage to surrounding biological tissues caused by high temperature, ensure that laser energy effectively acts on the target tissue, and improve surgical precision and safety.

[0039] The antireflective coating 3 comprises a first film layer 31 and a second film layer 32 sequentially stacked on the surface of the output end. The first film layer 31 is located on the side of the second film layer 32 away from the end cap 2, and the refractive index of the first film layer 31 is lower than that of the second film layer 32. The arrangement order of the film layers follows: air - low refractive index film layer - high refractive index film layer - end cap 2. Compared with a single-layer film, this double-layer structure has a wider bandwidth adaptability, can cover a wider infrared band, adapt to the wavelength requirements of different medical scenarios, and achieves a smoother refractive index transition by combining two layers of materials with different refractive indices, reducing interface scattering.

[0040] The first layer 31 is made of SiO2, Al2O3, MgO, Y2O3, ZrO2, or diamond; the second layer 32 is made of SiO2, Al2O3, MgO, Y2O3, ZrO2, or diamond. These materials have a high laser damage threshold, are chemically stable, and are not easily corroded in human body fluids, meeting biocompatibility requirements. In the same antireflective coating 3, the first layer 31 and the second layer 32 are made of different materials, and an optical interference structure is constructed by combining materials with different refractive indices.

[0041] The design of the film layer needs to follow the λ / 4 matching principle. This ratio is based on the impedance matching principle of multilayer film system. It adjusts the reflection phase of light waves at the interface to make the reflected light undergo destructive interference, thereby maximizing the transmittance in the 2-6μm working wavelength range.

[0042] The implementation methods of this application will be described below using specific scenarios.

[0043] Example 1: This design is for 2.1μm Ho:YAG laser ablation of kidney stones. End cap 2 features a cylindrical design, 3mm in length and 1mm in diameter at the output end face. This size is compatible with the ureteroscope's working channel, facilitating operation within narrow urinary tracts. The angle between the end cap 2 and the fiber optic body 1, as well as the laser output end face, is 0°, ensuring perpendicular beam incidence and emission, avoiding reflection loss and beam distortion caused by oblique incidence. End cap 2 is made of SiO2, due to its low absorption coefficient in the 2.1μm near-mid-infrared band, transmittance ≥90%, chemical stability, and good biocompatibility. The fusion interface between end cap 2 and fiber optic body 1 is optically polished, with a surface roughness ≤1nm and a defect level conforming to 10 / 5, to reduce scattering loss and ensure a smooth fusion interface. A double-layer antireflection coating 3 is deposited on the output end face, optimized for the 2.1μm center wavelength. The first film layer 31 (low refractive index film layer) is made of MgO with a thickness of 307 nm, and the second film layer 32 (high refractive index film layer) is made of ZrO2 with a thickness of 250 nm. The film thickness is designed based on the quarter-wavelength optical thickness principle, and the multilayer film interference effect is used to counteract surface reflection, so that the transmittance of the antireflection film 3 in the 2.1 μm band is ≥99%, thereby improving the laser energy utilization rate.

[0044] Example 2: Example 2 is designed for 2.9μm Er:YAG laser cutting of hard dental tissue, a band that coincides with the water absorption peak. The end cap 2 has a total length of 5mm and an output end face diameter of 2mm. The end cap 2 is made of Al2O3, which is highly hard and wear-resistant, suitable for the complex oral environment, and has a transmittance of ≥80% for the 2.9μm band. The end face polishing standard is the same as in Example 1 to ensure low-loss connection. The antireflective coating 3 uses a double-layer structure, with an antireflective band of 2.9μm. The first layer 31 (low refractive index layer) is made of Y2O3 with a thickness of 386nm, and the second layer 32 (high refractive index layer) is made of diamond with a thickness of 305nm. In addition to antireflection, the diamond layer provides extremely high surface hardness and chemical inertness, preventing saliva corrosion and mechanical scratching. The antireflective coating 3 has a transmittance of ≥99% for the 2.9μm band.

[0045] Example 3: Example 3 is applicable to femtosecond laser ablation of atherosclerotic plaques in the 5.7μm band. The end cap 2 has a total length of 2mm and an output end face diameter of 1mm, adaptable to the size of vascular interventional catheters. The end cap 2 is made of Y2O3, with a transmittance of ≥80% in the 5-6μm band, superior to quartz materials. The end face polishing and defect level are kept consistent to ensure optical quality. The antireflective coating 3 uses a double-layer structure with an antireflective band of 5.7μm. Due to the increased operating wavelength, the physical thickness of the coating layers is correspondingly increased to meet optical interference conditions. The first coating layer 31 (low refractive index coating layer) is made of Al2O3 with a thickness of 900nm, and the second coating layer 32 (high refractive index coating layer) is made of ZrO2 with a thickness of 683nm. The thicker coating layers ensure phase matching in the long wavelength band, and the antireflective coating 3 has a transmittance of ≥99% in the 5.7μm band.

[0046] Example 4: Example 4 describes tumor ablation therapy using a femtosecond laser in the 6.0 μm band. The end cap 2 has a total length of 3 mm and an output end face diameter of 2 mm. The complex geometry can be used for specific beam shaping or to adapt to the tumor tissue contact surface, optimizing energy distribution. The end cap 2 is made of YSZ, with a transmittance of ≥75% in the 6.0 μm band, and its thermal expansion coefficient matches well with the optical fiber, resulting in high thermal stability. The end face polishing standard remains unchanged. The antireflection coating 3 uses a double-layer structure, with an antireflection band of 6.0 μm. The first layer 31 (low refractive index layer) is made of MgO with a thickness of 926 nm, and the second layer 32 (high refractive index layer) is made of diamond with a thickness of 630 nm. The outer diamond layer provides chemical inert protection, and the antireflection coating 3 has a transmittance of ≥99% in the 6.0 μm band.

[0047] The encapsulation technology for the medical optical fiber body 1 and end cap 2 provided in Examples 1 to 4 includes the following steps: First, a sealing silicone grease is applied to the outer cladding near the tail end of the optical fiber body 1. Then, a glass sealant 4 is fitted onto the optical fiber body 1, and its position is adjusted so that the end face of the glass sealant 4 is flush with the tail end face of the optical fiber body 1. After the sealing silicone grease cures, it is fixed to the optical fiber body 1. The sealing silicone grease fills the microscopic gaps, playing a role in stress buffering and initial sealing. The glass sealant 4 serves as an intermediate transition component, matching the thermal expansion coefficients of the optical fiber and the end cap 2. Next, the optical fiber body 1 and the end cap 2, with the glass sealant 4 fixed, are clamped using a clamp, and the advance distance is adjusted to mechanically connect the optical fiber body 1 and the end cap 2. A fusion splicer is used to fuse the end cap 2 and the glass sealant 4. The discharge position is on the side where the glass sealant 4 is located to avoid high temperature directly acting on the microstructure area of ​​the optical fiber body 1. Once the fusion splicing is completed, the fiber body 1 and the end cap 2 can be encapsulated with high strength. After the glass seal 4 melts, it fills the interface gap and forms an airtight connection after cooling, ensuring the structural integrity and optical stability of the device in the internal environment.

[0048] In summary, the end cap 2, antireflective membrane 3, glass seal 4 and sealing silicone grease used in this application are all safe and non-toxic. They are not easily scratched during friction and collision, will not shed fine particles, and have no toxicity or risk of rejection when in direct contact with human organs and tissues.

[0049] The end cap 2 provided in this application has high transmittance, avoiding significant energy loss during femtosecond laser transmission. Simultaneously, the end cap 2 offers diverse shape options, adapting to the splicing of single-hole and nested-hole optical fiber bodies 1, satisfying the transmission requirements of multi-band, high-power lasers. The femtosecond laser exits from the end cap 2 at an angle ≤2°, with an exit laser spot diameter ≤1mm, ensuring sufficient energy density during ablation surgery.

[0050] The end cap 2 encapsulation technology provided in this application can stably connect the fiber body 1 and the end cap 2, requires a low fusion temperature, and can prevent damage to the microstructure of the fiber body 1. When used under high temperature and high pressure, ethylene oxide sterilization, or immersed in body fluids, it can prevent problems such as cracking, detachment, and water ingress of the fiber body 1 and the end cap 2, ensuring the safety of laser surgery.

[0051] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0052] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0053] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A medical mid-infrared hollow fiber optic transmission device, characterized in that, It includes: The optical fiber body (1) has an output end; End cap (2), the end cap (2) has a connection surface that connects to the output end of the optical fiber body (1), the end cap (2) is made of biocompatible inorganic non-metallic material, the infrared absorption cutoff wavelength of the end cap (2) is greater than 6μm, and the transmittance in the 2-6μm band is ≥50%; The connection structure includes a glass seal (4), which is disposed at the connection surface between the output end of the optical fiber body (1) and the end cap (2). The glass seal (4) forms an annular contact interface with the outer peripheral surface of the output end of the optical fiber body (1). The glass seal (4) is fused between the output end of the optical fiber body (1) and the connection surface of the end cap (2) to form a sealed connection between the optical fiber body (1) and the end cap (2).

2. The medical mid-infrared hollow fiber optic transmission device as described in claim 1, characterized in that: The end cap material includes at least one of SiO2, Al2O3, YAG, Si, Y2O3, and YSZ.

3. The medical mid-infrared hollow fiber optic transmission device as described in claim 2, characterized in that: When the end cap (2) is used in the 2-3μm band, the end cap material is SiO2, Al2O3, YAG, Si, Y2O3 or YSZ; When the end cap (2) is used in the 3-5μm band, the end cap material is Al2O3, YAG, Si, Y2O3 or YSZ; When the end cap (2) is used in the 5-6μm band, the end cap material is Si, Y2O3 or YSZ.

4. The medical mid-infrared hollow fiber optic transmission device as described in claim 1, characterized in that: The axial length of the end cap (2) is ≤10mm, the maximum diameter is ≤2mm, and the connecting surface and the output end of the end cap (2) are both planar with a surface roughness of ≤1nm.

5. The medical mid-infrared hollow fiber optic transmission device as described in claim 1, characterized in that: The output end surface of the end cap (2) is coated with an anti-reflection film (3). The anti-reflection film (3) includes a first film layer (31) and a second film layer (32) stacked sequentially on the output end surface. The first film layer (31) is located on the side of the second film layer (32) away from the end cap (2).

6. The medical mid-infrared hollow fiber optic transmission device as described in claim 5, characterized in that: The material of the first film layer (31) is SiO2, Al2O3, MgO, Y2O3, ZrO2 or diamond; The material of the second film layer (32) is SiO2, Al2O3, MgO, Y2O3, ZrO2 or diamond; The refractive index of the first film layer (31) is less than that of the second film layer (32); In the same antireflective membrane (3), the first membrane layer (31) and the second membrane layer (32) are made of different materials.

7. The medical mid-infrared hollow fiber optic transmission device as described in claim 1, characterized in that: The glass seal (4) is made of high borosilicate glass with a B2O3 content ≥10%; The inner diameter of the glass seal (4) is 10-20 μm larger than the outer diameter of the cladding of the optical fiber body (1), and the outer diameter of the glass seal (4) is ≤2 mm.

8. The medical mid-infrared hollow fiber optic transmission device as described in claim 1, characterized in that: The melting point of the glass seal (4) is lower than the melting point of the end cap (2); The melting point of the glass seal (4) is lower than that of the optical fiber body (1).

9. The medical mid-infrared hollow fiber optic transmission device as described in claim 1, characterized in that: The glass seal (4) has a ring-shaped structure and is fitted around the outer periphery of the output end of the optical fiber body (1).

10. The medical mid-infrared hollow fiber optic transmission device as described in claim 9, characterized in that: The connection structure also includes a sealing medium (5), which fills the gap between the glass seal (4) and the optical fiber body (1).

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