Dual-core anti-resonant fiber based on ultra-wideband

Abstract

The present invention discloses a dual-core anti-resonant optical fiber based on an ultra-wide band, and relates to the field of optical fiber communication technology. The present invention includes an outer cladding, an upper fiber core unit and a lower fiber core unit from the outside to the inside; the upper fiber core unit includes a first inner cladding, an upper fiber core is arranged at the center of the first inner cladding, a plurality of nested cladding tube assemblies are equidistantly arranged circumferentially in the first inner cladding region, a first elliptical cladding tube is arranged between adjacent nested cladding tube assemblies to fill the gap, the first elliptical cladding tube and the nested cladding tube assembly do not contact each other, and the nested cladding tube assembly is externally cut with the upper fiber core. The dual-core hollow-core anti-resonant optical fiber in the present invention not only ensures that it has the characteristics of an anti-resonant optical fiber, but also ensures that the light has extremely low restrictive loss during transmission from visible light to the optical communication band, and the overall anti-bending effect of the light is significant.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber communication, in particular to a dual-core anti-resonance optical fiber based on an ultra-wide band. Background Art

[0002] The visible light band generally refers to the band with a wavelength range of 390nm-760nm, which is widely used in precision spectroscopy, biomedicine, microscopic imaging, optical communications, scientific research and other fields. The optical fiber high-power transmission band is 1000-1080nm, and the communication band generally refers to the band with a wavelength range of 1260nm-1675nm.

[0003] At present, hollow-core antiresonant optical fiber has become a research hotspot due to its low time delay, low dispersion, low nonlinear coefficient and other characteristics. Existing research on hollow-core antiresonant optical fiber only exists in a single core, and research on the application band is also limited to one band, and its functional structure is relatively simple. Summary of the invention

[0004] The object of the present invention is to provide a dual-core anti-resonant optical fiber based on an ultra-wide band, which has very low limiting losses in different optical bands and has strong anti-bending ability.

[0005] To achieve the above object, the present invention provides the following technical solution: a dual-core anti-resonant optical fiber based on an ultra-wideband, comprising, from the outside to the inside, an outer cladding, an upper fiber core unit and a lower fiber core unit;

[0006] The upper fiber core unit comprises a first inner cladding, an upper fiber core is arranged at the center of the first inner cladding, a plurality of nested cladding tube assemblies are equidistantly arranged in the circumferential direction of the first inner cladding region, a first elliptical cladding tube is arranged between adjacent nested cladding tube assemblies to fill the gap, the first elliptical cladding tube and the nested cladding tube assembly do not contact each other, and the nested cladding tube assembly is circumscribed with the upper fiber core;

[0007] The lower fiber core unit includes a second inner cladding, a lower fiber core is arranged at the center of the second inner cladding, a plurality of fan-shaped cladding tubes are equidistantly arranged circumferentially in the second inner cladding region, a second elliptical cladding tube is arranged between adjacent fan-shaped cladding tubes to fill the gaps, the second elliptical cladding tube and the fan-shaped cladding tube do not contact each other, and the fan-shaped cladding tube is tangent to the lower fiber core.

[0008] Furthermore, the nested cladding tube assembly includes a first circular cladding tube and a second circular cladding tube, the diameter of the second circular cladding tube is smaller than that of the first circular cladding tube, and the second circular cladding tube is nested in the first circular cladding tube.

[0009] Furthermore, the diameter of the first circular cladding tube is 20 μm-22 μm, the diameter of the second circular cladding tube is 8 μm-10 μm, and the plurality of first circular cladding tubes are equidistantly arranged around the upper fiber core and tangent to the upper fiber core.

[0010] Furthermore, the side of the fan-shaped cladding tube facing the lower fiber core is an arc surface, the fan-shaped cladding tube is circumscribed with the lower fiber core through the arc surface, and a chamfer is provided between the arc and the radius of the fan-shaped cladding tube, and the radius range of the chamfer is 0.7μm-0.9μm.

[0011] Furthermore, the radius of the fan-shaped cladding tube is set to 10 μm-12 μm, and the central angle of the fan-shaped cladding tube is 75°.

[0012] Further, the major axis of the first elliptical cladding tube is set to 22 μm-25 μm, and the minor axis is set to 15 μm-18 μm;

[0013] The major axis of the second elliptical cladding tube is set to 12 μm-15 μm, and the minor axis is set to 7 μm-10 μm.

[0014] Furthermore, the outer cladding, the fan-shaped cladding tube, the first elliptical cladding tube, the nested cladding tube assembly and the second elliptical cladding tube are all made of silica material, and the refractive index of the silica material is in the range of 1.40-1.45.

[0015] Furthermore, the fan-shaped cladding tube, the first elliptical cladding tube, the first circular cladding tube, the second circular cladding tube and the second elliptical cladding tube are all filled with air, and the refractive index of air is lower than the refractive index of silicon dioxide.

[0016] Furthermore, the wall thicknesses of the fan-shaped cladding tube, the first elliptical cladding tube, the first circular cladding tube, the second circular cladding tube and the second elliptical cladding tube are all the same, and are all set to 0.5 μm-0.8 μm.

[0017] Furthermore, the upper core unit establishes a coordinate system with the center of the upper core as the origin of the coordinate system, the direction of the line connecting the centers of the upper core and the lower core is set as the Y-axis direction, and the direction perpendicular to the Y-axis is set as the X-axis direction, and the upper core unit is mirror-symmetrical with the Y-axis as the symmetry axis;

[0018] The lower core unit establishes a coordinate system with the center of the lower core as the origin of the coordinate system, the direction of the line connecting the centers of the upper core and the lower core is set to the Y-axis direction, and the direction perpendicular to the Y-axis direction is set to the X-axis direction. The lower core unit is mirror-symmetrical with the X-axis as the symmetry axis, and is mirror-symmetrical with the Y-axis as the symmetry axis.

[0019] The present invention has at least the following beneficial effects:

[0020] The dual-core hollow-core anti-resonant optical fiber of the present invention not only ensures that it has the characteristics of an anti-resonant optical fiber, but also ensures that the light has extremely low limiting loss during transmission from the visible light to the optical communication band, and the maximum loss is 7.07×10 -7dB / km. At the same time, the overall anti-bending effect of the light is significant. When the bending radius is in the range of 10cm-20cm, the maximum bending loss is 8.41×10 -6 dB / km.

[0021] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a cross-sectional schematic diagram of the overall structure of the present invention;

[0023] Figure 2 It is a cross-sectional fundamental mode diagram and a three-dimensional diagram of the upper core unit in the present invention;

[0024] Figure 3 It is a cross-sectional fundamental mode diagram and a three-dimensional diagram of the lower fiber core unit in the present invention;

[0025] Figure 4 It is a relationship diagram of the effective refractive index of the fundamental mode and the effective refractive index of the high-order mode of the upper core unit and the lower core unit in the present invention as a function of wavelength;

[0026] Figure 5 is a relationship diagram of the limiting loss of the optical fiber structure of the present invention varying with the incident wavelength from visible light to optical communication band;

[0027] Figure 6 It is a relationship diagram of the bending loss of the optical fiber structure of the present invention changing with the incident wavelength in the visible light, high-power transmission and optical communication bands.

[0028] Reference numerals:

[0029] 1. Outer cladding; 2. Upper fiber core unit; 21. First inner cladding; 22. Upper fiber core; 23. Nested cladding tube assembly; 231. First circular cladding tube; 232. Second circular cladding tube; 24. First elliptical cladding tube; 3. Lower fiber core unit; 31. Second inner cladding; 32. Lower fiber core; 33. Fan-shaped cladding tube; 34. Second elliptical cladding tube. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0031] See also Figure 1, the present invention provides a technical solution, which is mainly applied to the ultra-wide band of 0.5μm-1.6μm: a dual-core anti-resonant optical fiber based on the ultra-wide band, including an outer cladding 1, an upper fiber core unit 2 and a lower fiber core unit 3 from the outside to the inside;

[0032] The upper fiber core unit 2 comprises a first inner cladding 21, an upper fiber core 22 is arranged at the center of the first inner cladding 21, a plurality of nested cladding tube assemblies 23 are equidistantly arranged in the circumferential direction of the first inner cladding 21, a first elliptical cladding tube 24 is arranged between adjacent nested cladding tube assemblies 23 to fill the gap, the first elliptical cladding tube 24 and the nested cladding tube assemblies 23 are not in contact with each other, and the nested cladding tube assemblies 23 are circumscribed with the upper fiber core 22;

[0033] The lower fiber core unit 3 includes a second inner cladding 31, a lower fiber core 32 is arranged at the center of the second inner cladding 31, a plurality of fan-shaped cladding tubes 33 are equidistantly arranged circumferentially in the second inner cladding 31 region, a second elliptical cladding tube 34 is arranged between adjacent fan-shaped cladding tubes 33 to fill the gap, the second elliptical cladding tube 34 and the fan-shaped cladding tube 33 do not contact each other, and the fan-shaped cladding tube 33 is tangent to the lower fiber core 32.

[0034] According to the technical solution of this embodiment, a perfect matching layer is provided on the outer side of the outer cladding 1, and the thickness of the perfect matching layer is 1 μm-3 μm, so as to eliminate the difference between the model calculation and the actual transmission of the optical fiber.

[0035] It should be noted that the perfectly matched layer (PML) in the optical fiber is a special dielectric layer. By truncating the boundary setting in the FDTD region, the wave impedance of its medium is completely matched with the wave impedance of the adjacent medium. This design allows the incident wave to pass through the interface without reflection and enter the PML, thereby achieving lossless energy transmission. The introduction of 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.

[0036] The realization principle of the perfect matching layer is to set a boundary condition with the same material and matching wave impedance as the cladding outside the optical fiber cladding, so it can be regarded as a non-reflective absorption layer. When the light beam is incident on the perfect matching layer, it will not be reflected back immediately, but will gradually attenuate until it is finally absorbed. This non-reflective feature makes the perfect matching layer an ideal boundary condition in simulation analysis, especially when simulating and analyzing large mode area optical fibers, the use of the perfect matching layer can significantly improve the accuracy of the simulation results.

[0037] According to the technical solution of this embodiment, the nested cladding tube assembly 23 includes a first circular cladding tube 231 and a second circular cladding tube 232. The diameter of the second circular cladding tube 232 is smaller than that of the first circular cladding tube 231, and the second circular cladding tube 232 is nested in the first circular cladding tube 231. The hollow-core antiresonant optical fiber can reduce the limiting loss by using a nested circle method. The nested circle is based on the original cladding tube and shares a contact point, and a smaller cladding tube is installed to achieve a nested structure.

[0038] Furthermore, the diameter of the first circular cladding tube 231 is 20 μm-22 μm, the diameter of the second circular cladding tube 232 is 8 μm-10 μm, and the plurality of first circular cladding tubes 231 are equidistantly arranged around the upper fiber core 22 and tangent to the upper fiber core 22 .

[0039] According to the technical solution of this embodiment, the side of the fan-shaped cladding tube 33 facing the lower fiber core 32 is an arc surface, and the fan-shaped cladding tube 33 is tangent to the lower fiber core 32 through the arc surface, and a chamfer is provided between the arc and the radius of the fan-shaped cladding tube 33, and the radius range of the chamfer is 0.7μm-0.9μm. Setting the chamfer can reduce the scattering and loss of the incident light, which is beneficial to maintaining the quality of the light beam.

[0040] Furthermore, the radius of the fan-shaped cladding tube 33 is set to 10μm-12μm, and the central angle of the fan-shaped cladding tube 33 is 75°. This angle and structural design can make the incident light more concentrated in the area of ​​the lower fiber core 32, so as to facilitate stable transmission of light energy.

[0041] According to the technical solution of this embodiment, the major axis of the first elliptical cladding tube 24 is set to 10 μm-14 μm, and the minor axis is set to 6 μm-10 μm;

[0042] The major axis of the second elliptical cladding tube 34 is set to 12 μm-14 μm, and the minor axis is set to 7 μm-9 μm.

[0043] According to the technical solution of this embodiment, the outer cladding 1, the fan-shaped cladding tube 33, the first elliptical cladding tube 24, the nested cladding tube assembly 23 and the second elliptical cladding tube 34 are all made of silica material, and the refractive index of the silica material ranges from 1.40 to 1.45;

[0044] The fan-shaped cladding tube 33, the first elliptical cladding tube 24, the first circular cladding tube 231, the second circular cladding tube 232 and the second elliptical cladding tube 34 are all filled with air, and the refractive index of air is lower than the refractive index of silica, ensuring that the refractive index of air is lower than the refractive index of silica material, so as to facilitate the incident light to be concentrated in the upper fiber core 22 and the lower fiber core 32 areas.

[0045] Furthermore, the wall thicknesses of the fan-shaped cladding tube 33, the first elliptical cladding tube 24, the first circular cladding tube 231, the second circular cladding tube 232 and the second elliptical cladding tube 34 are all the same, which are all set to 0.5μm-0.8μm. The same wall thickness of the cladding tubes can better control the transmission mode of light, reduce the distortion and energy loss of the transmission mode, and simplify the manufacturing process.

[0046] According to the technical solution of this embodiment, the upper core unit 2 establishes a coordinate system with the center of the upper core 22 as the origin of the coordinate system, the direction of the connecting line between the centers of the upper core 22 and the lower core 32 is set as the Y-axis direction, and the direction perpendicular to the Y-axis direction is set as the X-axis direction. The upper core unit 2 is mirror-symmetrical with the Y-axis as the axis of symmetry.

[0047] The lower fiber core unit 3 establishes a coordinate system with the center of the lower fiber core 32 as the coordinate origin, the direction of the line connecting the centers of the upper fiber core 22 and the lower fiber core 32 is set to the Y-axis direction, and the direction perpendicular to the Y-axis direction is set to the X-axis direction. The lower fiber core unit 3 is mirror-symmetrical with the X-axis as the symmetry axis and is mirror-symmetrical with the Y-axis as the symmetry axis.

[0048] The upper fiber core 22 and the lower fiber core 32 are both distributed in a symmetrical structure, and units of different shapes are distributed alternately, so that the incident light can be concentrated on the upper fiber core 22 and the lower fiber core 32 to a greater extent, reducing scattering and loss during optical fiber transmission and improving transmission quality.

[0049] The present invention uses finite element simulation software COMSOL Multiphysics to perform simulation tests on this embodiment, adopts the finite element method and combines the perfect matching layer boundary absorption condition to perform theoretical calculations, and obtains the restrictive loss, nonlinear coefficient, bending loss and corresponding wavelength of the present invention.

[0050] Figure 2 and Figure 3 They are the cross-sectional fundamental mode diagram and three-dimensional diagram of the upper fiber core unit and the lower fiber core unit respectively; Figure 4 is a graph showing the relationship between the effective refractive index of the fundamental mode and the effective refractive index of the higher-order mode of the upper core unit and the lower core unit and the wavelength; Figure 5 The figure is a relationship diagram of the limiting loss of the optical fiber structure from the visible light to the optical communication band as a function of the incident wavelength; Figure 6 This is a graph showing the relationship between the bending loss of the optical fiber structure and the incident wavelength in the visible light, high-power transmission, and optical communication bands;

[0051] In summary, from Figure 5 It can be seen from the limiting loss of the fundamental mode that the maximum limiting loss of this optical fiber from the visible light to the optical communication band is 7.07×10 -7 dB / km, compared with the 0.22dB / km of the traditional single-core hollow-core anti-resonant fiber, the loss is greatly reduced. Figure 6 As shown in Figure 2, the maximum bending loss of optical fiber in the visible light, high power transmission, and optical communication bands is 8.41×10 -6 dB / km, the optical fiber has good bending resistance.

[0052] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0053] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When an element is referred to as being "assembled on", "installed on", "fixed on" or "set on" another element, it can be directly on the other element or there can also be a centered element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a centered element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and are not intended to be the only implementation method.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. Dual-core anti-resonant optical fiber based on ultra-wideband, characterized in that: From the outside to the inside, it includes an outer cladding (1), an upper fiber core unit (2) and a lower fiber core unit (3); The upper fiber core unit (2) comprises a first inner cladding (21), an upper fiber core (22) is arranged at the center of the first inner cladding (21), a plurality of nested cladding tube assemblies (23) are equidistantly arranged in the circumferential direction of the first inner cladding (21) region, a first elliptical cladding tube (24) is arranged between adjacent nested cladding tube assemblies (23) to fill the gap, the first elliptical cladding tube (24) and the nested cladding tube assembly (23) are not in contact with each other, and the nested cladding tube assembly (23) and the upper fiber core (22) are tangent to each other; The lower fiber core unit (3) comprises a second inner cladding (31), a lower fiber core (32) is arranged at the center of the second inner cladding (31), a plurality of fan-shaped cladding tubes (33) are equidistantly arranged in the circumferential direction of the second inner cladding (31), a second elliptical cladding tube (34) is arranged between adjacent fan-shaped cladding tubes (33) to fill the gap, the second elliptical cladding tube (34) and the fan-shaped cladding tube (33) do not contact each other, and the fan-shaped cladding tube (33) and the lower fiber core (32) are tangent to each other; The nested cladding tube assembly (23) comprises a first circular cladding tube (231) and a second circular cladding tube (232); the diameter of the second circular cladding tube (232) is smaller than that of the first circular cladding tube (231), and the second circular cladding tube (232) is nested in the first circular cladding tube (231); The major axis of the first elliptical cladding tube (24) is set to 22 μm-25 μm, and the minor axis is set to 15 μm-18 μm; The major axis of the second elliptical cladding tube (34) is set to 12 μm-15 μm, and the minor axis is set to 7 μm-10 μm.

2. The ultra-wideband dual-core anti-resonant optical fiber according to claim 1, characterized in that: The diameter of the first circular cladding tube (231) is 20 μm-22 μm, the diameter of the second circular cladding tube (232) is 8 μm-10 μm, and the plurality of first circular cladding tubes (231) are arranged equidistantly around the upper fiber core (22) and are tangential to the upper fiber core (22).

3. The ultra-wideband dual-core anti-resonant optical fiber according to claim 2, characterized in that: The side of the fan-shaped cladding tube (33) facing the lower fiber core (32) is an arc surface, the fan-shaped cladding tube (33) is circumscribed with the lower fiber core (32) via the arc surface, and a chamfer is provided between the arc and the radius of the fan-shaped cladding tube (33), and the radius range of the chamfer is 0.7 μm-0.9 μm.

4. The ultra-wideband dual-core anti-resonant optical fiber according to claim 3, characterized in that: The radius of the sector-shaped cladding tube (33) is set to 10 μm-12 μm, and the center angle of the sector-shaped cladding tube (33) is 75°.

5. The ultra-wideband dual-core anti-resonant optical fiber according to claim 4, characterized in that: The outer cladding (1), the fan-shaped cladding tube (33), the first elliptical cladding tube (24), the nested cladding tube assembly (23) and the second elliptical cladding tube (34) are all made of silica material, and the refractive index of the silica material is in the range of 1.40-1.

45.

6. The ultra-wideband dual-core anti-resonant optical fiber according to claim 5, characterized in that: The fan-shaped cladding tube (33), the first elliptical cladding tube (24), the first circular cladding tube (231), the second circular cladding tube (232) and the second elliptical cladding tube (34) are all filled with air, and the refractive index of the air is lower than the refractive index of silicon dioxide.

7. The ultra-wideband dual-core anti-resonant optical fiber according to claim 6, characterized in that: The tube wall thicknesses of the fan-shaped cladding tube (33), the first elliptical cladding tube (24), the first circular cladding tube (231), the second circular cladding tube (232) and the second elliptical cladding tube (34) are all the same, and are all set to be 0.5 μm-0.8 μm.

8. The ultra-wideband dual-core anti-resonant optical fiber according to claim 7, characterized in that: The upper fiber core unit (2) establishes a coordinate system with the center of the upper fiber core (22) as the coordinate origin, the direction of the line connecting the centers of the upper fiber core (22) and the lower fiber core (32) is set as the Y-axis direction, and the direction perpendicular to the Y-axis direction is set as the X-axis direction, and the upper fiber core unit (2) is mirror-symmetrical with the Y-axis as the symmetry axis; The lower fiber core unit (3) establishes a coordinate system with the center of the lower fiber core (32) as the coordinate origin, the direction of the line connecting the centers of the upper fiber core (22) and the lower fiber core (32) is set as the Y-axis direction, and the direction perpendicular to the Y-axis direction is set as the X-axis direction. The lower fiber core unit (3) is mirror-symmetrical with the X-axis as the symmetry axis, and is mirror-symmetrical with the Y-axis as the symmetry axis.

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