An ultra-wideband six-core anti-resonant optical fiber for mid and far infrared wave bands

Abstract

This invention discloses an ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared bands, belonging to the field of optical fiber communication technology. The six-core anti-resonant optical fiber of this invention comprises, from the outside to the inside along the fiber diameter, a perfectly matched layer, an outer cladding layer, and six light-guiding units arranged inside the outer cladding layer. The first light-guiding unit is located at the center of the outer cladding layer, and the second to sixth light-guiding units are arranged at a 72° angle within the outer cladding layer. o Symmetrical distribution. Each light guide unit has multiple nested tube assemblies equidistantly arranged along the circumference. These nested tube assemblies together form the air core region, operating in the 7.5~12.5 µm band. They exhibit extremely low confinement loss, near-zero dispersion, and low nonlinear coefficient, significantly improving the overall transmission performance and band coverage of the optical fiber.

Description

Technical Field

[0001] This invention belongs to the field of optical fiber communication technology, specifically an ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared bands. Background Technology

[0002] With the continuous development of integrated circuit manufacturing technology, photolithography, as a core technology for micro-nano fabrication, has placed increasingly stringent technical requirements on the wavelength of its light source and the performance indicators of its optical transmission system. Different wavelength light sources have their own unique technical advantages and application scenarios in fields such as photolithography, optical communication, and precision optical systems, thereby driving the continuous development and iterative upgrading of multi-band optical systems and fiber optic transmission technologies.

[0003] The mid- and far-infrared band possesses inherent characteristics such as a wide atmospheric transmission window and abundant molecular characteristic absorption peaks, giving it irreplaceable advantages in environmental monitoring, gas sensing, precision spectral analysis, infrared laser transmission, and space optical communication. This band can effectively cover the characteristic absorption spectral regions of various gas molecules, facilitating the detection of multi-component substances with high sensitivity and selectivity. Simultaneously, mid- and far-infrared light exhibits low transmission attenuation and strong anti-interference capabilities in the atmosphere, making it suitable for long-distance information transmission and detection in complex environments. Compared to the ultraviolet, visible, and near-infrared bands, the mid- and far-infrared band also features high power handling capacity, controllable thermal effects, and low damage to biological tissues, demonstrating significant technological advantages in high-power laser processing, medical diagnostics, and precision optical systems.

[0004] Currently, hollow-core antiresonant fiber is considered an important solution for mid- and far-infrared band transmission due to its low nonlinearity, near-zero dispersion, and low loss. However, existing research mainly focuses on single-core or dual-core structures, with limited research on multi-core and composite structures. Therefore, developing a composite hollow-core antiresonant fiber capable of low-loss, high-stability ultra-wideband transmission in the 7.5 ~ 12.5 µm mid- and far-infrared band is of great significance, as it can simultaneously meet the multi-band transmission requirements of applications such as communication and precision optical systems. Summary of the Invention

[0005] The purpose of this invention is to provide an ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band, which achieves ultra-low confining loss, near-zero dispersion, and low nonlinear coefficient in the mid- and far-infrared band, thus facilitating long-distance transmission and improving transmission quality.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] This invention provides an ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared bands. Along the fiber diameter, from the outside in, it comprises a perfectly matched layer, an outer cladding layer, and six light-guiding units arranged within the outer cladding layer. The first light-guiding unit is located at the center of the outer cladding layer, and the second to sixth light-guiding units are arranged at a 72° angle within the outer cladding layer. o Symmetrical distribution;

[0008] Both the first light guide unit and the sixth light guide unit are equipped with a first nested tube assembly. The first nested tube assembly forms a central air core area and an upper air core area. The first nested tube assembly includes, from the outside to the inside, a first type of large arc cladding tube, a first type of medium arc cladding tube, and a first type of small arc cladding tube. The three cladding tubes are concentric and their ends are all fused to the outer cladding.

[0009] Both the second and third light guide units are equipped with second nested tube assemblies. The second nested tube assemblies together form the upper left air core area and the upper right air core area. The second nested tube assembly includes, from the outside to the inside, a second type of large arc cladding tube, a first type of large circular cladding tube, and a first type of small circular cladding tube. The end of the second type of large arc cladding tube is fused to the outer cladding layer. The first type of large circular cladding tube and the first type of small circular cladding tube are tangent to the outer cladding layer and fused to the outer cladding layer.

[0010] Both the fourth and fifth light guiding units are equipped with a third nested tube assembly. The third nested tube assembly forms the lower left air core area and the lower right air core area. The third nested tube assembly includes, from the outside to the inside, a first type of elliptical arc cladding tube, a first type of elliptical cladding tube, and a second type of elliptical cladding tube. The end of the first type of elliptical arc cladding tube is fused to the outer cladding layer. The first type of elliptical cladding tube and the second type of elliptical cladding tube are tangent to the outer cladding layer and fused to the outer cladding layer.

[0011] The cladding wall thickness of the nested tube assemblies inside the six light guide units is different.

[0012] Preferably, the horizontal direction is defined as the X-axis and the vertical direction as the Y-axis. The center point of the sixth light guide unit is offset vertically upward by 79~81 µm relative to the center point of the first light guide unit. The center points of the second and third light guide units are symmetrical along the Y-axis. The center points of the fourth and fifth light guide units are symmetrical along the Y-axis.

[0013] Preferably, there are six of each of the first, second, and third nested tube assemblies, which are equidistant from each other at 60° intervals along the circumference inside the light guide unit. o They are symmetrically distributed and enclosed in a non-contact manner to form the corresponding air core area.

[0014] Preferably, the central air fiber core region, the upper left air fiber core region, the upper right air fiber core region, the lower left air fiber core region, the lower right air fiber core region, and the upper air fiber core region operate in the 7.5 ~ 12.5 µm band.

[0015] Preferably, the thickness of the perfect matching layer is 7~9 µm, the radius of the outer cladding layer is 390~410 µm, the radius of the first light guide unit and the sixth light guide unit is 70~78 µm, the radius of the second light guide unit and the third light guide unit is 66~74 µm, and the radius of the fourth light guide unit and the fifth light guide unit is 68~76 µm.

[0016] Preferably, in the first nested tube assembly, the first type of large arc cladding tube, the first type of medium arc cladding tube, and the first type of small arc cladding tube are concentric, and the distance between the center point and the center point of the light guide unit is 70~72 µm.

[0017] In the second nested tube assembly, the center point of the second type of large circular arc cladding tube is 64~66 µm away from the center point of the light guide unit, 7~9 µm away from the center point of the first type of large circular cladding tube, and 1~3 µm away from the center point of the first type of small circular cladding tube.

[0018] In the third nested tube assembly, the center point of the first type of elliptical arc-shaped cladding tube is 68~70 µm away from the center point of the light guide unit, 11~13 µm away from the center point of the first type of elliptical cladding tube, and 5~7 µm away from the center point of the second type of elliptical cladding tube.

[0019] Preferably, in the first light guiding unit and the sixth light guiding unit, the radius of the first type of large circular arc cladding tube is 34~36 µm, the radius of the first type of medium circular arc cladding tube is 24~26 µm, and the radius of the first type of small circular arc cladding tube is 14~16 µm.

[0020] In the second and third light guiding units, the radius of the second type of large circular arc cladding tube is 31~33 µm, the radius of the first type of large circular cladding tube is 12~14 µm, and the radius of the first type of small circular cladding tube is 5~7 µm.

[0021] In the fourth and fifth light guiding units, the major axis radius of the first type of elliptical arc-shaped cladding tube is 37~39 µm and the minor axis radius is 32~34 µm; the major axis radius of the second type of elliptical cladding tube is 19~21 µm and the minor axis radius is 14~16 µm; and the major axis radius of the third type of elliptical cladding tube is 8~10 µm and the minor axis radius is 5~7 µm.

[0022] Preferably, the perfect matching layer, the outer cladding layer, and each cladding tube in the light guide unit are all made of As2Se3 material, and the refractive index of the As2Se3 material is between 2.753 and 2.769.

[0023] Preferably, all six light guiding units, except for the cladding tube, are filled with air, and the refractive index of the air is 1.

[0024] Preferably, the wall thickness of each cladding tube in the first light guide unit is between 1.68 and 1.72 µm;

[0025] The wall thickness of each cladding tube in the second light guide unit is between 1.73 and 1.77 µm.

[0026] The wall thickness of each cladding tube in the third light guide unit is between 1.38 and 1.42 µm.

[0027] The wall thickness of each cladding tube in the fourth light guiding unit is between 1.48 and 1.52 µm.

[0028] The wall thickness of each cladding tube in the fifth light guide unit is between 1.58 and 1.62 µm.

[0029] The wall thickness of each cladding tube in the sixth light guide unit is between 1.28 and 1.32 µm.

[0030] By adopting the above technical solution, the present invention has at least the following significant effects:

[0031] The hollow-core antiresonant fiber provided by this invention consists of six hollow-core light-guiding units. Through systematic optimization and innovative improvements in material selection, structural parameters, and the addition of gap tube components, the overall transmission performance and band coverage are significantly enhanced. Simultaneously, the six-core layout provides inherent multi-channel parallel expansion capabilities for optical communication and spectral measurement systems, enabling independent, low-crosstalk synchronous transmission of six signals. It is particularly suitable for complex optical applications such as high-density integration, array coupling, and multi-mode measurement. Experimental results show that the heterogeneous six-core antiresonant fiber provided by this invention, while maintaining the characteristics of hollow-core antiresonant fiber, achieves extremely low confining loss in the mid- and far-infrared bands, with a maximum loss of only 3.11 × 10⁻⁶. -5 It exhibits low nonlinearity coefficients, ranging from 0.172 to 0.849 (W·km). -1 The dispersion varies within a certain range. Simultaneously, this optical fiber exhibits extremely low, near-zero dispersion characteristics, with a maximum dispersion of only 4.17 × 10⁻⁶. -13ps / (nm·km). Furthermore, thanks to its ultra-wideband, low-loss transmission characteristics, this optical fiber has broad application prospects in high-power laser transmission, spectral analysis, environmental monitoring, biomedical imaging, infrared communication, and space remote sensing, providing a stable and reliable solution for ultra-wideband, high-performance optical transmission systems in the mid- and far-infrared bands. Attached Figure Description

[0032] Figure 1 This is a schematic cross-sectional view of an ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band provided in an embodiment of the present invention.

[0033] Figure 2 These are the cross-sectional fundamental mode diagram and three-dimensional height representation diagram of the central air core region of the first light guide unit provided in this embodiment of the invention;

[0034] Figure 3 This is a cross-sectional fundamental mode diagram and a three-dimensional height representation diagram of the upper left air core region of the second light guide unit provided in this embodiment of the invention;

[0035] Figure 4 This is a cross-sectional fundamental mode diagram and a three-dimensional height representation diagram of the upper right air core region of the third light guide unit provided in this embodiment of the invention;

[0036] Figure 5 This is a cross-sectional fundamental mode diagram and a three-dimensional height representation diagram of the lower left air core region of the fourth light guide unit provided in this embodiment of the invention;

[0037] Figure 6 This is a cross-sectional fundamental mode diagram and a three-dimensional height representation diagram of the lower right air core region of the fifth light guide unit provided in this embodiment of the invention;

[0038] Figure 7 These are the cross-sectional fundamental mode diagram and three-dimensional height representation diagram of the upper air core region of the sixth light guide unit provided in this embodiment of the invention;

[0039] Figure 8 This is a graph showing the relationship between the fundamental mode confining loss of a six-core anti-resonant optical fiber and wavelength, provided in an embodiment of the present invention.

[0040] Figure 9 This is a graph showing the relationship between the mode field area of ​​the fundamental mode of a six-core anti-resonant optical fiber and wavelength, provided in an embodiment of the present invention.

[0041] Figure 10 This is a graph showing the relationship between the fundamental mode dispersion of a six-core anti-resonant optical fiber and wavelength, provided in an embodiment of the present invention.

[0042] Figure 11 This is a graph showing the relationship between the fundamental mode nonlinear coefficient of the six-core anti-resonant optical fiber and wavelength, provided in an embodiment of the present invention. Detailed Implementation

[0043] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The embodiments described below with reference to the accompanying drawings are illustrative and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this 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 should not be construed as limiting this invention.

[0045] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "arrangement," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a direct connection, or a connection through an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances. Furthermore, the term "an embodiment" or "embodiment" as used in this invention refers to a specific feature, structure, or characteristic that can be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0046] Please see Figure 1 The present invention provides an ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band, which is mainly used in the 7.5~12.5µm mid- and far-infrared band. Along the fiber diameter from the outside to the inside, it includes a perfect matching layer 1, an outer cladding layer 2, and a first light guide unit 3, a second light guide unit 4, a third light guide unit 5, a fourth light guide unit 6, a fifth light guide unit 7, and a sixth light guide unit 8 arranged in the outer cladding layer 2.

[0047] Specifically, the first light guide unit 3 has six identical first nested tube assemblies arranged equidistantly along the circumferential direction inside, and the first nested tube assemblies are 60° apart. o Symmetrically distributed and enclosing to form the central air core area 31, the first nested tube assembly consists of a first type of large arc cladding tube 32c, a first type of medium arc cladding tube 32b, and a first type of small arc cladding tube 32a.

[0048] The second light guide unit 4 has six identical second nested tube assemblies arranged equidistantly along the circumference inside, forming a 60° angle. o Symmetrically distributed, enclosing and forming the upper left air core area 41, the second nested tube assembly consists of a second type of large circular arc cladding tube 42c, a first type of large circular cladding tube 42b, and a first type of small circular cladding tube 42a.

[0049] The third light guide unit 5 has six identical second nested tube assemblies arranged equidistantly along the circumference, forming a 60° angle. o Symmetrically distributed, enclosing and forming the upper right air core area 51.

[0050] The fourth light guide unit 6 has six identical third nested tube assemblies arranged equidistantly along the circumference, forming a 60° angle. o Symmetrically distributed, enclosing and forming the lower left air core area 61, the third nested tube assembly consists of a first type of elliptical arc-shaped cladding tube 62c, a first type of elliptical cladding tube 62b, and a second type of elliptical cladding tube 62a.

[0051] The fifth light guide unit 7 has six identical third nested tube assemblies arranged equidistantly along the circumference, which together form the lower right air fiber core area 71.

[0052] The sixth light guide unit 8 has six identical first nested tube assemblies arranged equidistantly along the circumference inside, which together form the upper air fiber core area 81.

[0053] In this embodiment, the radius of the outer cladding layer 2 is 390~410 µm. This outer cladding layer thickness design can minimize the optical field coupling of the central air core region 31, the upper left air core region 41, the upper right air core region 51, the lower left air core region 61, the lower right air core region 71, and the upper air core region 81.

[0054] In this embodiment, the radii of the first light guide unit and the sixth light guide unit are 70 ~ 78 µm, the radii of the second light guide unit and the third light guide unit are 66 ~ 74 µm, and the radii of the fourth light guide unit and the fifth light guide unit are 68 ~ 76 µm.

[0055] In this embodiment, the first light guide unit is located at the center of the outer cladding layer, and the second, third, fourth, fifth, and sixth light guide units are arranged at a 72° angle within the outer cladding layer. o The light guides are symmetrically distributed, and the distances from the second to the sixth light guide units to the center point of the outer cladding are all 79~81 µm.

[0056] In this embodiment, the central air core region 31, the upper left air core region 41, the upper right air core region 51, the lower left air core region 61, the lower right air core region 71, and the upper air core region 81 operate at 7.5~12.5 µm.

[0057] See Figure 1 and Figure 2 , Figure 2The diagram shows the cross-sectional fundamental mode and three-dimensional height representation of the central air core region of the first light guiding unit. As can be seen from the diagram, light of the corresponding wavelength is essentially confined to the central air core region, allowing for excellent transmission within this area. In this embodiment, the first light guiding unit 3 has six identical first nested tube assemblies spaced equidistantly along its circumference, with the six first nested tube assemblies forming a 60° angle. o Symmetrically distributed, enclosing and forming the central air core area 31, the first nested tube assembly includes, from the outside to the inside, a first type of large arc cladding tube 32c, a first type of medium arc cladding tube 32b, and a first type of small arc cladding tube 32a, with the ends of the cladding tubes fused to the outer cladding 2.

[0058] See Figure 1 and Figure 3 , Figure 3 The diagram shows the cross-sectional fundamental mode and three-dimensional height representation of the upper left air core region of the second light guide unit. As can be seen from the diagram, light of the corresponding wavelength is essentially confined to the upper left air core region, allowing for excellent transmission within this area. In this embodiment, the second light guide unit 4 contains six identical second nested tube assemblies spaced equidistantly along the circumference, with the six second nested tube assemblies forming a 60° angle. o Symmetrically distributed, enclosing and forming the upper left air core area 41, the second nested tube assembly includes, from the outside to the inside, a second type of large circular arc cladding tube 42c, a first type of large circular cladding tube 42b, and a first type of small circular cladding tube 42a. The end of the second type of large circular arc cladding tube 42c is fused to the outer cladding layer 2. The first type of large circular cladding tube 42b and the first type of small circular cladding tube 42a are simultaneously tangent to the outer cladding layer 2 and fused to the outer cladding layer 2.

[0059] See Figure 1 and Figure 4 , Figure 4 The diagram shows the cross-sectional fundamental mode and three-dimensional height representation of the upper right air core region of the third light guide unit. As can be seen from the diagram, light of the corresponding wavelength is essentially confined to the upper right air core region, allowing for excellent transmission within this area. In this embodiment, the third light guide unit 5 has a similar structure to the second light guide unit 4, differing only in the wall thickness of the cladding tube.

[0060] See Figure 1 and Figure 5 , Figure 5 The diagram shows the cross-sectional fundamental mode and three-dimensional height representation of the lower left air core region of the fourth light guide unit. As can be seen from the diagram, light of the corresponding wavelength is essentially confined to the lower left air core region, allowing for good transmission within this area. In this embodiment, the fourth light guide unit 6 contains six identical third nested tube assemblies spaced equidistantly along the circumference, with the six third nested tube assemblies forming a 60° angle. oSymmetrically distributed, enclosing and forming the lower left air core area 61, the third nested tube assembly includes, from the outside to the inside, a first type of elliptical arc-shaped cladding tube 62c, a first type of elliptical arc-shaped cladding tube 62b, and a second type of elliptical cladding tube 62a. The end of the first type of elliptical arc-shaped cladding tube 62c is fused to the outer cladding layer 2. The first type of elliptical arc-shaped cladding tube 62b and the second type of elliptical cladding tube 62a are tangent to the outer cladding layer 2 and fused to it.

[0061] See Figure 1 and Figure 6 , Figure 6 The diagram shows the cross-sectional fundamental mode and three-dimensional height representation of the lower right air core region of the fifth light guide unit. As can be seen from the diagram, light of the corresponding wavelength is essentially confined to the lower right air core region, allowing for excellent transmission within this area. In this embodiment, the fifth light guide unit 7 has a similar structure to the fourth light guide unit 6, differing only in the wall thickness of the cladding tube.

[0062] See Figure 1 and Figure 7 , Figure 7 The diagram shows the cross-sectional fundamental mode and three-dimensional height representation of the upper air core region of the sixth light guide unit. As can be seen from the diagram, light of the corresponding wavelength is basically confined to the upper air core region and can be transmitted well in this region.

[0063] In this embodiment, the sixth light guide unit 8 has a similar structure to the first light guide unit 3, except that the wall thickness of the cladding tube is different.

[0064] In this embodiment, the horizontal direction is defined as the X-axis and the vertical direction as the Y-axis. The center point of the sixth light guide unit 8 is offset vertically upward by 79~81 µm relative to the center point of the first light guide unit 3. The second light guide unit 4 and the third light guide unit 5 have similar structures, except that the wall thickness is different. The center points of the second light guide unit 4 and the third light guide unit 5 are symmetrical along the Y-axis. The fourth light guide unit 6 and the fifth light guide unit 7 have similar structures, except that the wall thickness is different. The center points of the fourth light guide unit 6 and the fifth light guide unit 7 are symmetrical along the Y-axis.

[0065] In the technical solution of this embodiment, a perfect matching layer 1 is provided on the outer side of the outer cladding layer 2, and the thickness of the perfect matching layer 1 is 7~9 µm, which is used to eliminate the difference between optical fiber in model calculation and actual transmission.

[0066] It's important to note that the Perfectly Matched Layer (PML) in optical fiber is a special dielectric layer. By setting a truncated boundary in the finite-difference time-domain region, the wave impedance of its medium is perfectly matched to that of the adjacent medium. This design allows incident waves to pass through the interface without reflection and enter the PML, thus achieving low-loss energy transmission. The introduction of the PML primarily addresses the discrepancy between the optical fiber model in the simulation environment and the actual optical fiber environment. By setting appropriate boundary conditions, the environmental differences between the two are effectively eliminated, making the simulation results closer to reality. The implementation principle of the PML is to set a boundary condition on the outside of the fiber cladding that is the same material as the cladding and has a matching wave impedance; therefore, it can be considered a non-reflective absorbing layer. When a beam of light enters the PML, it is not immediately reflected back but gradually attenuates until it is 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 perfectly matched PML can significantly improve the accuracy of the simulation results.

[0067] Regarding the technical solution of this embodiment, the radius of the first type of large circular arc cladding tube 32c is 34 ~ 36 µm, the radius of the first type of medium circular arc cladding tube 32b is 24 ~ 26 µm, and the radius of the first type of small circular arc cladding tube 32a is 14 ~ 16 µm.

[0068] The radius of the second type of large circular cladding tube 42c is 31 ~ 33 µm, the radius of the first type of large circular cladding tube 42b is 12 ~ 14 µm, and the radius of the first type of small circular cladding tube 42a is 5 ~ 7 µm.

[0069] The first type of elliptical clad tube 62c has a major axis radius of 37~39 µm and a minor axis radius of 32~34 µm; the first type of elliptical clad tube 62b has a major axis radius of 19~21 µm and a minor axis radius of 14~16 µm; and the second type of elliptical clad tube 62a has a major axis radius of 8~10 µm and a minor axis radius of 5~7 µm.

[0070] Furthermore, in the first light guiding unit, the first type of large circular arc cladding tube, the first type of medium circular arc cladding tube, and the first type of small circular arc cladding tube are concentric structures, and the distance between the center point and the center point of the first light guiding unit is 70~72 µm.

[0071] Furthermore, in the sixth light guide unit, the first type of large circular arc cladding tube, the first type of medium circular arc cladding tube, and the first type of small circular arc cladding tube are concentric structures, with the center point being 70~72 µm away from the center point of the sixth light guide unit.

[0072] Furthermore, in the second light guiding unit, the center point of the second type of large circular cladding tube is 64~66 µm away from the center point of the second light guiding unit, 7~9 µm away from the center point of the first type of large circular cladding tube 42b, and 1~3 µm away from the center point of the first type of small circular cladding tube 42a.

[0073] Furthermore, in the third light guiding unit, the center point of the second type of large circular cladding tube is 64~66 µm away from the center point of the third light guiding unit, 7~9 µm away from the center point of the first type of large circular cladding tube, and 1~3 µm away from the center point of the first type of small circular cladding tube.

[0074] Furthermore, in the fourth light guiding unit, the center point of the first type of elliptical cladding tube is 68~70 µm away from the center point of the fourth light guiding unit, 11~13 µm away from the center point of the first type of elliptical cladding tube 62b, and 5~7 µm away from the center point of the second type of elliptical cladding tube 62a.

[0075] Furthermore, in the fifth light guiding unit, the center point of the first type of elliptical cladding tube is 68~70 µm away from the center point of the fifth light guiding unit, 11~13 µm away from the center point of the first type of elliptical cladding tube, and 5~7 µm away from the center point of the second type of elliptical cladding tube.

[0076] In this embodiment, the perfectly matched layer 1, outer cladding layer 2, first type large circular arc cladding tube 32c, first type medium circular arc cladding tube 32b, first type small circular arc cladding tube 32a, second type large circular arc cladding tube 42c, first type large circular cladding tube 42b, first type small circular cladding tube 42a, first type elliptical arc cladding tube 62c, first type elliptical cladding tube 62b, and second type elliptical cladding tube 62a are all made of As2Se3 material. The refractive index of the As2Se3 material is between 2.753 and 2.769. Compared with traditional SiO2 material, this material has weaker absorption characteristics in the mid- and far-infrared bands, which is beneficial to reducing the loss during light transmission.

[0077] In this embodiment, all six light guiding units, except for the cladding tube itself, are filled with air, and the refractive index of air is 1. Furthermore, the refractive index of air is lower than that of SiO2 and As2Se3 materials, which facilitates the concentration of incident light in the central air core region 31, the upper left air core region 41, the upper right air core region 51, the lower left air core region 61, the lower right air core region 71, and the upper air core region 81.

[0078] Regarding the technical solution of this embodiment, the wall thickness of the first type of large arc cladding tube 32c, the first type of medium arc cladding tube 32b, and the first type of small arc cladding tube 32a in the first light guiding unit is between 1.68 and 1.72 µm.

[0079] The wall thickness of the second type of large circular arc cladding tube 42c, the first type of large circular cladding tube 42b, and the first type of small circular cladding tube 42a in the second light guiding unit is between 1.73 and 1.77 µm.

[0080] The wall thickness of the second type of large circular arc cladding tube, the first type of large circular cladding tube, and the first type of small circular cladding tube in the third light guide unit is between 1.38 and 1.42 µm.

[0081] The wall thickness of the first type of elliptical arc-shaped cladding tube 62c, the first type of elliptical cladding tube 62b, and the second type of elliptical cladding tube 62a in the fourth light guiding unit is between 1.48 and 1.52 µm.

[0082] The wall thickness of the first type of elliptical arc-shaped cladding tube and the second type of elliptical cladding tube in the fifth light guide unit is between 1.58 and 1.62 µm.

[0083] The wall thickness of the first type of large circular arc cladding tube, the first type of medium circular arc cladding tube, and the first type of small circular arc cladding tube in the sixth light guiding unit is between 1.28 and 1.32 µm.

[0084] Regarding the technical solution of this embodiment, the number of nested tube assemblies in the central air fiber core area 31, the upper left air fiber core area 41, the upper right air fiber core area 51, the lower left air fiber core area 61, the lower right air fiber core area 71, and the upper air fiber core area 81 are all 6, which are enclosed in a non-contact manner, effectively reducing the leakage of optical signals and avoiding the generation of node loss.

[0085] Furthermore, the ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band provided in this embodiment was simulated and tested using the finite element simulation software COMSOL Multiphysics. Theoretical calculations were performed using the finite element method and combined with the absorption conditions of the perfectly matched layer boundary to obtain simulation results such as confining loss, mode area, nonlinear coefficient, dispersion, and corresponding wavelength.

[0086] Figure 8 This is a graph showing the relationship between the fundamental mode limiting loss of this optical fiber and wavelength. From... Figure 8 As can be seen, the maximum limiting loss of this optical fiber in the mid-far-infrared ultrawideband is only 3.11 × 10⁻⁶. -5 With a loss of dB / m, compared to the transmission loss of approximately 0.2 dB / km in traditional single-mode fiber, the loss is significantly reduced, demonstrating excellent low-loss transmission characteristics.

[0087] Figure 9 This is a graph showing the relationship between the fundamental mode area of ​​the optical fiber and wavelength. From... Figure 9 As can be seen from this, the mode field area of ​​this hollow antiresonant fiber ranges from 1.90 × 10⁻⁶. 3 ~ 3.87×10 3 µm 2 Between these, there is a large mode field area, which can significantly suppress nonlinear effects, improve the fiber damage threshold, and enhance mode field stability and transmission fidelity.

[0088] Figure 10 This is a graph showing the relationship between the fundamental mode dispersion of the optical fiber and wavelength. From... Figure 10 As can be seen, the dispersion of this hollow antiresonant fiber in the 7.5 ~ 12.5 µm band is close to zero, with a maximum dispersion of only 4.17 × 10⁻⁶. -13 ps / (nm·km), near-zero dispersion fiber can effectively suppress pulse broadening and dispersion effects, ensuring signal stability and high-precision transmission in ultrafast laser systems and long-distance communications.

[0089] Figure 11 This is a graph showing the relationship between the fundamental mode nonlinearity coefficient of the optical fiber and wavelength. From... Figure 11 As can be seen, the nonlinear coefficient of this hollow-core antiresonant fiber is low, ranging from 0.172 to 0.849 (W·km). -1 The range varies. Therefore, this optical fiber, by reducing signal distortion and energy loss, can improve transmission efficiency, support higher power, and maintain signal stability, thus playing an important role in applications such as high-power laser transmission and fiber optic communication sensing.

[0090] The foregoing has illustrated and described the basic principles, main features, and advantages of this invention. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications should fall within the protection scope of this invention.

Claims

1. An ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band, characterized in that, The fiber includes, from the outside to the inside, a perfect matching layer, an outer cladding layer, and six light guide units arranged within the outer cladding layer. The first light guide unit is located at the center of the outer cladding layer, and the second to sixth light guide units are arranged at a 72° angle within the outer cladding layer. o Symmetrical distribution; Both the first light guide unit and the sixth light guide unit are equipped with a first nested tube assembly. The first nested tube assembly forms a central air core area and an upper air core area. The first nested tube assembly includes, from the outside to the inside, a first type of large arc cladding tube, a first type of medium arc cladding tube, and a first type of small arc cladding tube. The three cladding tubes are concentric and their ends are all fused to the outer cladding. Both the second and third light guide units are equipped with second nested tube assemblies. The second nested tube assemblies together form the upper left air core area and the upper right air core area. The second nested tube assembly includes, from the outside to the inside, a second type of large arc cladding tube, a first type of large circular cladding tube, and a first type of small circular cladding tube. The end of the second type of large arc cladding tube is fused to the outer cladding layer. The first type of large circular cladding tube and the first type of small circular cladding tube are tangent to the outer cladding layer and fused to the outer cladding layer. Both the fourth and fifth light guiding units are equipped with a third nested tube assembly. The third nested tube assembly forms the lower left air core area and the lower right air core area. The third nested tube assembly includes, from the outside to the inside, a first type of elliptical arc cladding tube, a first type of elliptical cladding tube, and a second type of elliptical cladding tube. The end of the first type of elliptical arc cladding tube is fused to the outer cladding layer. The first type of elliptical cladding tube and the second type of elliptical cladding tube are tangent to the outer cladding layer and fused to the outer cladding layer. The cladding wall thickness of the nested tube assemblies inside the six light guide units is different.

2. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, Define the horizontal direction as the X-axis and the vertical direction as the Y-axis. The center point of the sixth light guide unit is offset vertically upwards by 79~81 µm relative to the center point of the first light guide unit. The center points of the second and third light guide units are symmetrical along the Y-axis. The center points of the fourth and fifth light guide units are symmetrical along the Y-axis.

3. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, The first, second, and third nested tube assemblies each have six units, which are equidistant from each other at 60° intervals along the circumference inside the light guide unit. o They are symmetrically distributed and enclosed in a non-contact manner to form the corresponding air core area.

4. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, The central air fiber core region, upper left air fiber core region, upper right air fiber core region, lower left air fiber core region, lower right air fiber core region, and upper air fiber core region operate in the 7.5 ~ 12.5 µm band.

5. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, The thickness of the perfect matching layer is 7~9 µm, the radius of the outer cladding layer is 390~410 µm, the radius of the first light guide unit and the sixth light guide unit is 70~78 µm, the radius of the second light guide unit and the third light guide unit is 66~74 µm, and the radius of the fourth light guide unit and the fifth light guide unit is 68~76 µm.

6. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, In the first nested tube assembly, the first type of large arc cladding tube, the first type of medium arc cladding tube, and the first type of small arc cladding tube are concentric structures, and the distance between the center point and the center point of the light guide unit is 70~72 µm. In the second nested tube assembly, the center point of the second type of large circular arc cladding tube is 64~66 µm away from the center point of the light guide unit, 7~9 µm away from the center point of the first type of large circular cladding tube, and 1~3 µm away from the center point of the first type of small circular cladding tube. In the third nested tube assembly, the center point of the first type of elliptical arc-shaped cladding tube is 68~70 µm away from the center point of the light guide unit, 11~13 µm away from the center point of the first type of elliptical cladding tube, and 5~7 µm away from the center point of the second type of elliptical cladding tube.

7. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, In the first light guiding unit and the sixth light guiding unit, the radius of the first type of large circular arc cladding tube is 34 ~ 36 µm, the radius of the first type of medium circular arc cladding tube is 24 ~ 26 µm, and the radius of the first type of small circular arc cladding tube is 14 ~ 16 µm. In the second and third light guiding units, the radius of the second type of large circular arc cladding tube is 31~33 µm, the radius of the first type of large circular cladding tube is 12~14 µm, and the radius of the first type of small circular cladding tube is 5~7 µm. In the fourth and fifth light guiding units, the major axis radius of the first type of elliptical arc-shaped cladding tube is 37~39 µm and the minor axis radius is 32~34 µm; the major axis radius of the second type of elliptical cladding tube is 19~21 µm and the minor axis radius is 14~16 µm; and the major axis radius of the third type of elliptical cladding tube is 8~10 µm and the minor axis radius is 5~7 µm.

8. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, The perfect matching layer, the outer cladding layer, and each cladding tube in the light guide unit are all made of As2Se3 material, and the refractive index of the As2Se3 material is between 2.753 and 2.

769.

9. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, Of the six light guiding units, all except the cladding tube are filled with air, and the refractive index of the air is 1.

10. The ultra-wideband six-core anti-resonant optical fiber for the mid- and far-infrared band according to claim 1, characterized in that, The wall thickness of each cladding tube in the first light guide unit is between 1.68 and 1.72 µm; The wall thickness of each cladding tube in the second light guide unit is between 1.73 and 1.77 µm. The wall thickness of each cladding tube in the third light guide unit is between 1.38 and 1.42 µm. The wall thickness of each cladding tube in the fourth light guiding unit is between 1.48 and 1.52 µm. The wall thickness of each cladding tube in the fifth light guide unit is between 1.58 and 1.62 µm. The wall thickness of each cladding tube in the sixth light guide unit is between 1.28 and 1.32 µm.

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