A heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission

Abstract

The present invention discloses a heterogeneous three-core anti-resonant fiber for visible light to mid-infrared transmission, belonging to the technical field of optical fiber communication. The heterogeneous three-core anti-resonant fiber of the present invention includes an outer cladding from the outside to the inside along the fiber diameter, and a first inner cladding, a second inner cladding and a third inner cladding are arranged inside the outer cladding. A plurality of structurally identical embedding tube assemblies are equidistantly arranged along the circumferential direction inside the first inner cladding, the second inner cladding and the third inner cladding. The embedding tube assemblies enclose to form an upper air core region, a lower left air core region and a lower right air core region. The upper air core region, the lower left air core region and the lower right air core region in the present invention work in the 4 µm band, the 2 µm band and the 1 µm band respectively, and have extremely low confinement losses in the three working bands, and at the same time have good bending resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber communication, and specifically relates to a heterogeneous three-core anti-resonant optical fiber for transmission from visible light to mid-infrared. Background Art

[0002] The visible light band is not only widely used in environments sensitive to electromagnetic interference (hospitals, airplanes, etc.), but also because of its extremely small absorption and scattering coefficients in water, compared with traditional acoustic communications, underwater visible light communication (UMVLC) has advantages such as high bandwidth and low latency, and is often used for high-speed information exchange between autonomous underwater vehicles (AUVs). The mid-infrared band is widely used to analyze the spectral characteristics of biological molecules (such as proteins, fats, DNA, etc.), and is coupled to tissue absorption characteristics, and is used for precise cutting and treatment in laser surgery.

[0003] At present, the research on hollow-core antiresonant fibers is mostly focused on single-core and dual-core fibers, while the research on triple-core and composite structures is still relatively limited. In addition, the existing fiber structures have a single function and are limited to a single band or single-core low-loss transmission design. There are few hollow-core antiresonant fibers that can meet the requirements of working in the near-infrared band to the mid-infrared band. Summary of the invention

[0004] The purpose of the present invention is to provide a heterogeneous three-core anti-resonant optical fiber for visible light to mid-infrared transmission, which achieves ultra-low restrictive loss in the visible light to mid-infrared band and has extremely low bending loss, which is conducive to achieving long-distance transmission and improving transmission quality.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] The present invention provides a heterogeneous three-core anti-resonant optical fiber for transmission from visible light to mid-infrared, which includes an outer cladding from the outside to the inside along the radial direction of the optical fiber, wherein a first inner cladding, a second inner cladding and a third inner cladding are arranged in the outer cladding.

[0007] A plurality of nested tube assemblies with the same structure are arranged equidistantly in the circumferential direction inside the first inner cladding, the second inner cladding and the third inner cladding, and the plurality of nested tube assemblies with the same structure together form an air core region;

[0008] The nested tube assemblies are respectively: a first nested tube assembly, a second nested tube assembly and a third nested tube assembly;

[0009] The first nested tube assembly includes, from outside to inside, a first type of circular cladding tube, a first type of large elliptical cladding tube, and a first type of small elliptical cladding tube, all of which are tangent to the outer cladding and fused to the outer cladding;

[0010] The second nested sleeve assembly includes, from outside to inside, a first type of semi-elliptical cladding tube, a second type of semi-elliptical cladding tube, and a third type of circular cladding tube. The first type of semi-elliptical cladding tube and the second type of semi-elliptical cladding tube are both welded to the outer cladding, and the third type of circular cladding tube is tangent to and welded to the outer cladding;

[0011] The third nested sleeve assembly includes, from outside to inside, a second type of circular cladding tube, a second type of large elliptical cladding tube, and a second type of small elliptical cladding tube, all of which are tangent to and welded to the outer cladding.

[0012] Preferably, a plurality of the first nested sleeve assemblies surround and form an upper air core region, a plurality of the second nested sleeve assemblies surround and form a lower left air core region, and a plurality of the third nested sleeve assemblies surround and form a lower right air core region. The upper air core region, the lower left air core region, and the lower right air core region are symmetrically distributed at 120°;

[0013] The upper air core region, the lower left air core region, and the lower right air core region operate in the 4 µm band, the 2 µm band, and the 1 µm band respectively.

[0014] Preferably, the diameter of the outer cladding is between 380 µm and 400 µm.

[0015] Preferably, a plurality of the first nested sleeve assemblies are symmetrically distributed in a C5 pattern, and the plurality of the first nested sleeve assemblies do not contact each other;

[0016] A plurality of the second nested sleeve assemblies are symmetrically distributed in a C4 pattern, and the plurality of the second nested sleeve assemblies do not contact each other;

[0017] A plurality of the third nested sleeve assemblies are symmetrically distributed in a C5 pattern, and the plurality of the third nested sleeve assemblies do not contact each other.

[0018] Preferably, the diameter of the first type of circular cladding tube is between 75 µm and 79 µm, the diameter of the second type of circular cladding tube is between 53 µm and 57 µm, and the diameter of the third type of circular cladding tube is between 35 µm and 38 µm.

[0019] Preferably, the major axis of the first type of large elliptical cladding tube is between 32 µm and 34 µm, the minor axis is between 20 µm and 22 µm, the major axis of the second type of large elliptical cladding tube is between 23 µm and 25 µm, the minor axis is between 14 µm and 16 µm, the major axis of the first type of small elliptical cladding tube is between 14 µm and 17 µm, the minor axis is between 11 µm and 13 µm, and the major axis of the second type of small elliptical cladding tube is between 10 µm and 12 µm, the minor axis is between 7 µm and 9 µm;

[0020] The major axis of the first type of semi-elliptical cladding tube is 54 µm to 56 µm, and the minor axis is 36 µm to 38 µm. The major axis of the second type of semi-elliptical cladding tube is 36 µm to 38 µm, and the minor axis is 27 µm to 29 µm.

[0021] Preferably, the outer cladding, the second type of circular cladding tube, the second type of large elliptical cladding tube, and the second type of small elliptical cladding tube are all made of silica, and the refractive index range of the silica material is between 1.37 and 1.46.

[0022] Preferably, the first type of circular cladding tube, the third type of circular cladding tube, the first type of large elliptical cladding tube, the first type of small elliptical cladding tube, the first type of semi-elliptical cladding tube, and the second type of semi-elliptical cladding tube are all made of ZBLAN, and the refractive index range of the ZBLAN material is between 1.47 and 1.56.

[0023] Preferably, between the first type of circular cladding tube, the first type of large elliptical cladding tube, and the first type of small elliptical cladding tube, between the first type of semi-elliptical cladding tube, the second type of semi-elliptical cladding tube, and the third type of circular cladding tube, between the second type of circular cladding tube, the second type of large elliptical cladding tube, and the second type of small elliptical cladding tube, inside the first type of small elliptical cladding tube, the second type of small elliptical cladding tube, and the third type of circular cladding tube, and in the upper air core region, the lower left air core region, and the lower right air core region are all filled with air.

[0024] Preferably, the wall thicknesses of the second type of circular cladding tube, the second type of large elliptical cladding tube, and the second type of small elliptical cladding tube all satisfy:

[0025] ;

[0026] wherein, is the designed operating wavelength, represents the refractive index of the silica material of the cladding tube, represents the refractive index of air, is the anti-resonance order;

[0027] The wall thicknesses of the first type of circular cladding tube, the third type of circular cladding tube, the first type of large elliptical cladding tube, the first type of small elliptical cladding tube, the first type of semi-elliptical cladding tube, and the second type of semi-elliptical cladding tube all satisfy:

[0028] ;

[0029] wherein, is the designed operating wavelength, represents the refractive index of the ZBLAN material of the cladding tube.

[0030] With the above technical solution, the present invention has at least the following beneficial effects:

[0031] In addition to ensuring the characteristics of anti-resonant fiber, the heterogeneous three-core hollow anti-resonant fiber in the present invention ensures extremely low confinement loss during light transmission in the visible to mid-infrared wavelength range, and the maximum loss is 7.40×10 - 10 dB / m. At the same time, the bending loss of the fiber in the X direction at 2μm, 3μm, and 4μm wavelength bands is at most 5.60×10 -9 dB / m, and the maximum in the Y direction is 1.33×10 -9 dB / m, indicating good bending resistance of the fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic cross-sectional view of the overall structure of the heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission provided by an embodiment of the present invention;

[0033] Figure 2 are the fundamental mode diagram and 3D diagram of the cross-section of the upper air core region in an embodiment of the present invention;

[0034] Figure 3 are the fundamental mode diagram and 3D diagram of the cross-section of the lower left air core region in an embodiment of the present invention;

[0035] Figure 4 are the fundamental mode diagram and 3D diagram of the cross-section of the lower right air core region in an embodiment of the present invention;

[0036] Figure 5 is a relationship diagram of the confinement loss varying with the incident wavelength of a heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission provided by an embodiment of the present invention in the near-infrared to mid-infrared wavelength range;

[0037] Figure 6 is a relationship diagram of the bending loss in the X direction varying with the bending radius at 2μm, 3μm, and 4μm of a heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission provided by an embodiment of the present invention;

[0038] Figure 7 is a relationship diagram of the bending loss in the Y direction varying with the bending radius at 2μm, 3μm, and 4μm of a heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The following will further describe in detail the specific embodiments of the present invention in conjunction with the drawings and embodiments. The embodiments described by referring to the drawings are illustrative and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0040] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by terms such as “upper”, “lower”, “front”, “rear”, “end”, “bottom” and “side” are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0041] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "installation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a direct connection, or a connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0043] See also Figure 1 The embodiment of the present invention provides a heterogeneous three-core antiresonant optical fiber for visible light to mid-infrared transmission, which is applied to the visible light to mid-infrared band. It includes an outer cladding 1 from the outside to the inside along the radial direction of the optical fiber. The first inner cladding 2, the second inner cladding 3 and the third inner cladding 4 are arranged in the outer cladding 1. The first inner cladding 2 includes an upper air core region 5, the second inner cladding 3 includes a lower left air core region 6, and the third inner cladding 4 includes a lower right air core region 7.

[0044] In this embodiment, the diameter of the outer cladding 1 is 380µm~400µm; the thickness design of this outer cladding can minimize the optical field coupling of the upper air core region 5, the lower left air core region 6 and the lower right air core region 7 to the greatest extent, so as to stably operate in their independent bands.

[0045] In this embodiment, the upper air core region 5, the lower left air core region 6 and the lower right air core region 7 operate in the 4µm band, the 2µm band and the 1µm band respectively.

[0046] See also Figure 2 In this embodiment, a plurality of first nested tube assemblies with the same structure are arranged equidistantly along the circumferential direction inside the first inner cladding 2, and the plurality of first nested tube assemblies are symmetrically distributed in C5 to enclose the upper air core region 5. The first nested tube assemblies include a first type circular cladding tube 8, a first type large elliptical cladding tube 9, and a first type small elliptical cladding tube 10 from the outside to the inside, all of which are tangent to the outer cladding 1 and fused to the outer cladding 1. It should be noted that the plurality of first nested tube assemblies do not contact each other.

[0047] See Figure 3 Figure 3 , in this embodiment, a plurality of second embedded sleeve components with the same structure are equidistantly arranged along the circumferential direction inside the second inner cladding 3. The plurality of second embedded sleeve components are distributed in a C4 symmetry to enclose and form the lower left air core region 6. The second embedded sleeve component includes a first type of semi-elliptical cladding tube 11, a second type of semi-elliptical cladding tube 12, and a third type of circular cladding tube 13 from the outside to the inside. The first type of semi-elliptical cladding tube 11 and the second type of semi-elliptical cladding tube 12 are both welded to the outer cladding 1. The third type of circular cladding tube 13 is tangent to the outer cladding 1 and welded to the outer cladding 1, and the first type of semi-elliptical cladding tube 11, the second type of semi-elliptical cladding tube 12, and the third type of circular cladding tube 13 do not contact each other. It should be noted that the plurality of second embedded sleeve components do not contact each other.

[0048] See Figure 4 Figure 4 , in this embodiment, a plurality of third embedded sleeve components with the same structure are equidistantly arranged along the circumferential direction inside the third inner cladding 4. The plurality of third embedded sleeve components are distributed in a C5 symmetry to enclose and form the lower right air core region 7. The third embedded sleeve component includes a second type of circular cladding tube 14, a second type of large elliptical cladding tube 15, and a second type of small elliptical cladding tube 16 from the outside to the inside, all of which are tangent to the outer cladding 1 and welded to the outer cladding 1. It should be noted that the plurality of third embedded sleeve components do not contact each other.

[0049] In this embodiment, the upper air core region 5, the lower left air core region 6, and the lower right air core region 7 are symmetrically distributed at 120°. Such a symmetrical structure distribution minimizes the optical field coupling degree of the three air core regions and enables them to operate stably in their respective independent bands.

[0050] For the technical solution of this embodiment, a perfectly matched layer is provided on the outer side of the outer cladding 1, and the thickness of the perfectly matched layer is 8 µm to 12 µm, which is used to eliminate the differences between the fiber in model calculation and actual transmission.

[0051] It should be noted that the perfectly matched layer (PML) in the optical fiber is a special dielectric layer. By setting the truncation boundary in the finite-difference time-domain region, the wave impedance of its medium is exactly matched with that of the adjacent medium. This design enables the incident wave to pass through the interface without reflection and enter the PML, thereby achieving lossless energy transmission. The introduction of the PML is mainly to solve the problem of the difference between the optical fiber model in the simulation environment and the actual optical fiber environment. By setting appropriate boundary conditions, the environmental difference between the two is effectively eliminated, making the simulation results closer to the actual situation. The implementation principle of the PML is to set boundary conditions on the outer side of the cladding of the optical fiber that are the same as the cladding material and have a matched wave impedance. Therefore, it can be regarded as a non-reflective absorption layer. When the light beam is incident on the PML, it will not be immediately reflected back, but will gradually decay until it is finally completely absorbed. This non-reflective characteristic makes the PML an ideal boundary condition in simulation analysis. Especially when simulating large-mode-area optical fibers, the use of the PML can significantly improve the accuracy of the simulation results.

[0052] For the technical solution of this embodiment, the diameter of the first type of circular cladding tube 8 is 75 µm to 79 µm, the diameter of the second type of circular cladding tube 14 is 53 µm to 57 µm, and the diameter of the third type of circular cladding tube 13 is 35 µm to 38 µm.

[0053] Furthermore, the major axis of the first type of large elliptical cladding tube 9 is 32 µm to 34 µm, the minor axis is 20 µm to 22 µm, the major axis of the second type of large elliptical cladding tube 15 is 23 µm to 25 µm, the minor axis is 14 µm to 16 µm, the major axis of the first type of small elliptical cladding tube 10 is 14 µm to 17 µm, the minor axis is 11 µm to 13 µm, and the major axis of the second type of small elliptical cladding tube 16 is 10 µm to 12 µm, the minor axis is 7 µm to 9 µm.

[0054] Furthermore, the major axis of the first type of semi-elliptical cladding tube 11 is 54 µm to 56 µm, the minor axis is 36 µm to 38 µm, the major axis of the second type of semi-elliptical cladding tube 12 is 36 µm to 38 µm, the minor axis is 27 µm to 29 µm. This semi-elliptical structure design can make the incident light more concentrated in the lower left air core region 6 to facilitate stable light energy transmission.

[0055] For the technical solution of this embodiment, the first type of circular cladding tube 8, the third type of circular cladding tube 13, the first type of large elliptical cladding tube 9, the first type of small elliptical cladding tube 10, the first type of semi-elliptical cladding tube 11, and the second type of semi-elliptical cladding tube 12 are all made of ZBLAN material, and the refractive index range of the ZBLAN material is between 1.47 and 1.56, which is greater than the refractive index of the silica material. Compared with the traditional silica material, this material has weaker absorption characteristics in the mid-infrared band, which can reduce the loss during light transmission.

[0056] The outer cladding 1, the second type of circular cladding tube 14, the second type of large elliptical cladding tube 15, and the second type of small elliptical cladding tube 16 are all made of silica material, and the refractive index range of the silica material is between 1.37 and 1.46.

[0057] For the technical solution of this embodiment, between the first type of circular cladding tube 8, the first type of large elliptical cladding tube 9, and the first type of small elliptical cladding tube 10, between the first type of semi-elliptical cladding tube 11, the second type of semi-elliptical cladding tube 12, and the third type of circular cladding tube 13, between the second type of circular cladding tube 14, the second type of large elliptical cladding tube 15, and the second type of small elliptical cladding tube 16, and inside the first type of small elliptical cladding tube 10, the second type of small elliptical cladding tube 16, and the third type of circular cladding tube 13, the upper air core region 5, the lower left air core region 6, and the lower right air core region 7 are all filled with air, and the refractive index of the air is less than the refractive indices of the silica and ZBLAN materials, ensuring that the refractive index of the air is less than the refractive index of the silica material, which is convenient for making the incident light concentrate in the upper air core region 5, the lower left air core region 6, and the lower right air core region 7.

[0058] For the technical solution of this embodiment, the wall thicknesses of the second type of circular cladding tube 14, the second type of large elliptical cladding tube 15, and the second type of small elliptical cladding tube 16 all satisfy:

[0059] ;

[0060] wherein, is the designed working wavelength, represents the refractive index of the cladding silica material, represents the refractive index of the air, is the anti-resonant order number, which is a positive integer.

[0061] Furthermore, the wall thicknesses of the first type of circular cladding tube 8, the third type of circular cladding tube 13, the first type of large elliptical cladding tube 9, the first type of small elliptical cladding tube 10, the first type of semi-elliptical cladding tube 11, and the second type of semi-elliptical cladding tube 12 all satisfy:

[0062] ;

[0063] Among them, is the working wavelength of the design, represents the refractive index of the cladding ZBLAN material, represents the refractive index of air, is the anti-resonant order, which is a positive integer.

[0064] Furthermore, based on the working wavelength of this embodiment and the selected refractive indices of silica and ZBLAN materials, the wall thicknesses of the first type of circular cladding tube 8, the first type of large elliptical cladding tube 9, and the first type of small elliptical cladding tube 10 are 0.2 µm to 0.4 µm, the wall thicknesses of the first type of semi-elliptical cladding tube 11, the second type of semi-elliptical cladding tube 12, and the third type of circular cladding tube 13 are 0.4 µm to 0.8 µm, and the wall thicknesses of the second type of circular cladding tube 14, the second type of large elliptical cladding tube 15, and the second type of small elliptical cladding tube 16 are 0.8 µm to 1.1 µm.

[0065] For the technical solution of this embodiment, the number of embedded tube assemblies in the upper air-core region and the lower right air-core region is 5, and the number of embedded tube assemblies in the lower left air-core region is 4, effectively reducing the leakage of optical signals and avoiding the generation of node losses.

[0066] Furthermore, use the finite element simulation software COMSOL Multiphysics to perform simulation tests on this embodiment, adopt the finite element method and combine the perfectly matched layer boundary absorption condition for theoretical calculation to obtain the confinement loss and the corresponding wavelength.

[0067] From Figure 5 it can be seen from the confinement loss of the fundamental mode that the maximum value of the confinement loss of this fiber from the visible light, high-power transmission, optical communication band to the mid-infrared band is 7.4×10 -10 dB / m. Compared with 2.2×10 -4 dB / km of the traditional single-core hollow anti-resonant fiber, the loss is greatly reduced. At the same time, as shown in Figure 6 , Figure 7 , the maximum bending loss of this fiber in the X direction at 2 µm, 3 µm, and 4 µm bands is 5.60×10 -9 dB / m, and the maximum in the Y direction is 1.33×10 -9 dB / m, indicating that the fiber has good anti-bending performance.

[0068] The above has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission, which includes an outer cladding from outside to inside along the radial direction of the fiber. Inside the outer cladding, a first inner cladding, a second inner cladding, and a third inner cladding are arranged. It is characterized in that a plurality of structurally identical embedded tube assemblies are equidistantly arranged along the circumferential direction inside the first inner cladding, the second inner cladding, and the third inner cladding. The plurality of structurally identical embedded tube assemblies enclose an upper air core region, a lower left air core region, and a lower right air core region. The upper air core region, the lower left air core region, and the lower right air core region are symmetrically distributed at 120°; the embedded tube assemblies are respectively: a first embedded tube assembly, a second embedded tube assembly, and a third embedded tube assembly; the first embedded tube assembly includes a first type of circular cladding tube, a first type of large elliptical cladding tube, and a first type of small elliptical cladding tube from outside to inside. They are all tangent to the outer cladding and are fused to the outer cladding; the second embedded tube assembly includes a first type of semi-elliptical cladding tube, a second type of semi-elliptical cladding tube, and a third type of circular cladding tube from outside to inside. The first type of semi-elliptical cladding tube and the second type of semi-elliptical cladding tube are both fused to the outer cladding. The third type of circular cladding tube is tangent to the outer cladding and is fused to the outer cladding; the third embedded tube assembly includes a second type of circular cladding tube, a second type of large elliptical cladding tube, and a second type of small elliptical cladding tube from outside to inside. They are all tangent to the outer cladding and are fused to the outer cladding; the diameter of the first type of circular cladding tube is 75 µm to 79 µm, the diameter of the second type of circular cladding tube is 53 µm to 57 µm, and the diameter of the third type of circular cladding tube is 35 µm to 38 µm; the major axis of the first type of large elliptical cladding tube is 32 µm to 34 µm, and the minor axis is 20 µm to 22 µm. The major axis of the second type of large elliptical cladding tube is 23 µm to 25 µm, and the minor axis is 14 µm to 16 µm. The major axis of the first type of small elliptical cladding tube is 14 µm to 17 µm, and the minor axis is 11 µm to 13 µm. The major axis of the second type of small elliptical cladding tube is 10 µm to 12 µm, and the minor axis is 7 µm to 9 µm; the major axis of the first type of semi-elliptical cladding tube is 54 µm to 56 µm, and the minor axis is 36 µm to 38 µm. The major axis of the second type of semi-elliptical cladding tube is 36 µm to 38 µm, and the minor axis is 27 µm to 29 µm.

2. The heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission according to claim 1, characterized in that the upper air core region, the lower left air core region, and the lower right air core region work in the 4 µm band, the 2 µm band, and the 1 µm band respectively.

3. The heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission according to claim 1, characterized in that, the diameter of the outer cladding is 380 µm to 400 µm.

4. The heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission according to claim 1, characterized in that a plurality of the first embedded tube assemblies are symmetrically distributed in C5, and the plurality of the first embedded tube assemblies do not contact each other; a plurality of the second embedded tube assemblies are symmetrically distributed in C4, and the plurality of the second embedded tube assemblies do not contact each other; Multiple said third nested tube assemblies are distributed in a C5 symmetry, and multiple said third nested tube assemblies do not contact each other.

5. The heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission according to claim 1, characterized in that, The said outer cladding layer, second type of circular cladding tube, second type of large elliptical cladding tube, and second type of small elliptical cladding tube are all made of silica material, and the refractive index range of the silica material is between 1.37 and 1.

46.

6. The heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission according to claim 5, wherein The first type of circular cladding tube, third type of circular cladding tube, first type of large elliptical cladding tube, first type of small elliptical cladding tube, first type of semi-elliptical cladding tube, and second type of semi-elliptical cladding tube are all made of ZBLAN material, and the refractive index range of the ZBLAN material is between 1.47 and 1.

56.

7. The heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission according to claim 4, characterized in that, Between the first type of circular cladding tube, first type of large elliptical cladding tube, and first type of small elliptical cladding tube, between the first type of semi-elliptical cladding tube, second type of semi-elliptical cladding tube, and third type of circular cladding tube, between the second type of circular cladding tube, second type of large elliptical cladding tube, and second type of small elliptical cladding tube, inside the first type of small elliptical cladding tube, second type of small elliptical cladding tube, and third type of circular cladding tube, the upper air core region, lower left air core region, and lower right air core region are all filled with air.

8. The heterogeneous three-core anti-resonant fiber for visible to mid-infrared transmission according to claim 1, characterized in that, The wall thicknesses of the second type of circular cladding tube, the second type of large elliptical cladding tube, and the second type of small elliptical cladding tube all satisfy: ； Among them, is the designed working wavelength, represents the refractive index of the cladding tube made of silica, represents the refractive index of air, is the anti-resonant order; The wall thicknesses of the first type of circular cladding tube, the third type of circular cladding tube, the first type of large elliptical cladding tube, the first type of small elliptical cladding tube, the first type of semi-elliptical cladding tube, and the second type of semi-elliptical cladding tube all satisfy: ； Among them, is the designed working wavelength, represents the refractive index of the ZBLAN material of the cladding tube.

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