Non-nested special-shaped anti-resonance hollow-core optical fiber

Abstract

The invention provides a non-nested special-shaped anti-resonance hollow-core optical fiber, and relates to the technical field of anti-resonance hollow optical fibers, the non-nested special-shaped anti-resonance hollow-core optical fiber comprises a plurality of special-shaped anti-resonance microstructures which are uniformly distributed along the inner wall of an outer cladding at equal intervals according to the circumferential direction of the outer cladding, and all the special-shaped anti-resonance microstructures define a fiber core area at the center of the outer cladding; each special-shaped anti-resonance microstructure and the outer cladding layer form a microstructure closed cavity, and an air gap is formed between every two adjacent microstructure closed cavities; each special-shaped anti-resonance microstructure comprises a plurality of sections of sub-structures, any two adjacent sections of sub-structures keep a tangent relation, and at least two adjacent sections of sub-structures have opposite curvature directions. The anti-resonance micro-structure has the beneficial effects that by introducing the non-nested anti-resonance micro-structure design comprising multiple sections of sub-structures with opposite curvature directions, the technical problem that in the prior art, a nested capillary structure only has a single curvature, so that the shape design and the performance optimization are limited is successfully solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of anti-resonant hollow optical fiber, and particularly to a non-nested special anti-resonant hollow optical fiber. BACKGROUND

[0002] Due to the low overlap of the transmission medium and the optical field with the glass material, the hollow optical fiber has the advantages of high transmission speed, high damage threshold and low nonlinearity. In 2002, Litchinitser and other scholars first extended the anti-resonant principle to the field of hollow optical fiber, and constructed a special anti-resonant hollow optical fiber (HC-ARF) system. Its transmission mechanism requires that the wavelength of light strictly avoids the resonance region of the microstructure ring.

[0003] Such optical fiber significantly reduces the energy coupling of the mode field and the medium interface through the coherent cancellation effect of the leaky waveguide caused by the specific microstructure ring thickness, and can theoretically achieve the loss limit beyond the traditional quartz optical fiber. This characteristic makes it exhibit unique advantages of low loss, low delay and high power carrying in the non-transparent waveband of ultraviolet and mid-infrared. The nested capillary structure of the special anti-resonant hollow optical fiber currently only has a single curvature, and there is still room for optimization in its shape design and exploration. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a non-nested special anti-resonant hollow optical fiber, comprising:

[0005] A plurality of special anti-resonant microstructures are uniformly and equidistantly distributed along the inner wall of the outer cladding according to the circumferential direction of the outer cladding, and all the special anti-resonant microstructures form a core region at the center of the outer cladding.

[0006] Each of the special anti-resonant microstructures forms a microstructure closed cavity with the outer cladding, and the adjacent microstructure closed cavities have an air gap therebetween.

[0007] Each of the special anti-resonant microstructures comprises a plurality of substructures, any two adjacent substructures maintain a tangent relationship, and the curvature directions of at least two adjacent substructures are opposite.

[0008] Preferably, the special anti-resonant microstructure comprises two mirror-symmetrical half-microstructure outer arc segments, each of the half-microstructure outer arc segments comprises a plurality of substructures.

[0009] Preferably, the substructure in each of the half-microstructure outer arc segments comprises:

[0010] A first circular arc segment, a straight line segment, a second circular arc segment and a third circular arc segment are sequentially connected from the core region to the inner wall of the outer cladding.

[0011] Preferably, the first arc segment and the straight line segment are tangent, the straight line segment and the second arc segment are tangent, and the second arc segment and the third arc segment are tangent.

[0012] Preferably, the curvatures of the second arc segment and the third arc segment are in opposite directions.

[0013] Preferably, the wall thicknesses of the first arc segment, the straight line segment, the second arc segment, and the third arc segment are equal everywhere.

[0014] Preferably, each of the half-microstructure outer arc segments comprises:

[0015] A first arc segment, a second arc segment, and a third arc segment connected in sequence from the core region to the inner wall of the cladding.

[0016] Preferably, the first arc segment and the second arc segment are inscribed, and the second arc segment and the third arc segment are circumscribed.

[0017] Preferably, the wall thicknesses of the first arc segment, the second arc segment, and the third arc segment are equal everywhere.

[0018] Preferably, the curvatures of the third arc segments of different half-microstructure outer arc segments are in opposite directions.

[0019] The above technical solution has the following advantages or beneficial effects:

[0020] 1. A plurality of independent shaped anti-resonant microstructures are uniformly distributed on the inner wall of the cladding of the optical fiber to form a core region, replacing the traditional nested capillary structure. This non-nested design allows each microstructure to form an independent closed cavity with the cladding and be separated from each other by air gaps, significantly reducing the mutual influence between the microstructures and providing greater flexibility for performance control of the optical fiber.

[0021] 2. Each shaped anti-resonant microstructure is composed of multiple substructures with tangent and opposite curvatures. This complex and controllable curvature variation allows the optical fiber to more accurately control the transmission mode of the light field in the quartz non-transparent waveband such as ultraviolet and mid-infrared, further reducing the energy coupling between the mode field and the medium interface. This successfully solves the technical problem of the existing technology that the nested capillary structure only has a single curvature, limiting shape design and performance optimization. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 For Example 1 of the present application, a structure diagram of a non-nested shaped anti-resonant hollow core optical fiber;

[0023] Figure 2 For Example 1, a structure diagram of a half-microstructure outer arc segment;

[0024] Figure 3 Loss spectrum curve of the shaped anti-resonant hollow fiber in Example 1;

[0025] Figure 4 Schematic diagram of the quarter surface mode phase distribution of the shaped anti-resonant hollow fiber in Example 1;

[0026] Figure 5 Corresponding phase oscillation situation of the arc length extension along the gap of the shaped anti-resonant hollow fiber in Example 1;

[0027] Figure 6 Schematic diagram of the structure of the semi-microstructure outer arc segment of the shaped anti-resonant hollow fiber in Example 2;

[0028] Figure 7 Schematic diagram of the structure of the shaped anti-resonant hollow fiber in Example 2;

[0029] Figure 8 Loss spectrum curve of the shaped anti-resonant hollow fiber in Example 2;

[0030] Figure 9 Schematic diagram of the end face structure of the shaped anti-resonant hollow fiber in the preferred embodiment of the present application. DETAILED DESCRIPTION

[0031] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments. The present application is not limited to this embodiment, and other embodiments can also fall within the scope of the present application as long as they meet the main idea of the present application.

[0032] In the preferred embodiment of the present application, based on the above-mentioned problems existing in the prior art, a non-nested shaped anti-resonant hollow fiber is provided, as shown in Figure 1 , which comprises:

[0033] A plurality of shaped anti-resonant microstructures 2 are uniformly and equidistantly distributed along the inner wall of the outer cladding 1 in the circumferential direction of the outer cladding 1, and all the shaped anti-resonant microstructures 2 form a core region 3 at the center of the outer cladding 1.

[0034] Each shaped anti-resonant microstructure 2 forms a microstructure closed cavity 20 with the outer cladding 1, and there is an air gap 30 between adjacent microstructure closed cavities 20.

[0035] Each shaped anti-resonant microstructure 2 comprises a plurality of substructures, any two adjacent substructures maintain tangential relationship, and the curvature directions of at least two adjacent substructures are opposite.

[0036] Specifically, in the radial direction from the outside to the inside of the optical fiber, the optical fiber comprises: an outer cladding layer 1, a plurality of identical-shaped heteromorphic anti-resonant microstructures 2 located in the space surrounded by the inner surface of the outer cladding layer, and a core region 3 formed by all the heteromorphic anti-resonant microstructures; wherein the number of heteromorphic anti-resonant microstructures 2 is preferably 5-7, and they are uniformly and equidistantly distributed along the circumferential direction of the inner surface of the outer cladding layer.

[0037] Each heteromorphic anti-resonant microstructure 2 has an outer arc composed of a plurality of continuous substructures, including at least three circular arc segments or a combination of straight line segments.

[0038] Any two adjacent substructures maintain tangential relationship, and the curvature directions of at least two adjacent substructures are opposite.

[0039] In a preferred embodiment of the present application, the heteromorphic anti-resonant microstructure comprises two mirror-symmetrical half-microstructure outer arc segments 4, each of which comprises a plurality of substructures.

[0040] The non-nested heteromorphic anti-resonant hollow optical fiber of the present application has the following advantages:

[0041] Lower loss: the complex and controllable curvature design enables the optical fiber to more effectively confine the light field within the core, theoretically achieving lower transmission loss than the prior art, breaking through the loss limit of traditional quartz optical fiber.

[0042] Higher transmission efficiency and wider wavelength range: the non-nested and curvature diversified design provides more flexible light field control, enabling the optical fiber to maintain low loss characteristics in a wider wavelength range, especially in the ultraviolet and mid-infrared wavelength ranges which have higher requirements for optical fiber performance.

[0043] Strong design flexibility and tunability: the non-nested and multi-segment substructure design allows for flexible adjustment of the shape, size and curvature of the microstructure according to different application requirements, thereby optimizing the performance of the optical fiber such as loss, dispersion and power carrying capacity, providing greater freedom for the design and manufacture of optical fibers.

[0044] In order to more specifically explain the technical effects and implementation principles of the non-nested heteromorphic anti-resonant hollow optical fiber of the present application, two embodiments are provided below for specific description.

[0045] Embodiment one:

[0046] In this embodiment, the substructure in each half-microstructure outer arc segment 4 comprises:

[0047] A first circular arc segment 21, a straight line segment 22, a second circular arc segment 23 and a third circular arc segment 24 connected in turn from the core region to the inner wall of the outer cladding layer.

[0048] In the embodiment, the first arc segment 21 and the straight line segment 22 are tangent, the straight line segment 22 and the second arc segment 23 are tangent, and the second arc segment 23 and the third arc segment 24 are tangent.

[0049] In the preferred embodiment of the present application, the curvature directions of the second arc segment 23 and the third arc segment 24 are opposite.

[0050] In the preferred embodiment of the present application, the wall thicknesses of the first arc segment 21, the straight line segment 22, the second arc segment 23 and the third arc segment 24 are equal everywhere.

[0051] Specifically, in the embodiment, as shown in Figure 1 the core diameter of the core region is 46.5 um, and the larger core size can make the light wave experience fewer reflections or leaks in unit distance.

[0052] As shown in Figure 1 the outer cladding 1 adopts a circular outer sleeve tube, which includes six special-shaped anti-harmonic microstructures 2. The half-microstructure outer arc segment 4 is as shown in Figure 2 from the core region 3 to the direction of the outer sleeve tube is the first arc segment 21, the straight line segment 22, the second arc segment 23 and the third arc segment 24.

[0053] In the preferred embodiment of the present application, as shown in Figure 2 the central angle of the first arc segment 21 is 90°, the ratio of the arc length (um) to the central angle (°) is between 0.27 and 0.31, the length ratio of the straight line segment 22 to the core radius is between 1.9 and 2.1, the selected core radius is 22.5 um, and the length ratios of the second arc segment 23 and the third arc segment 24 to the core radius are between 0.7 and 1.1 and between 0.4 and 0.9, respectively.

[0054] Specifically, as shown in Figure 2 the first arc segment 21 and the straight line segment 22 are tangent, the straight line segment 22 and the second arc segment 23 are tangent, the second arc segment 23 and the third arc segment 24 are tangent, and the curvature directions of the second arc segment 23 and the third arc segment 24 are opposite.

[0055] Further, these arc segments do not intersect and do not exceed the reasonable spatial boundary.

[0056] As shown in Figure 2 a plurality of substructures constitute the half-microstructure outer arc 4, and the thickness of the microstructure wall is uniform everywhere, which is preferably 1.13 um in the embodiment.

[0057] After the half-microstructure outer arc segment 4 is quantified, the complete special-shaped anti-harmonic microstructure 2 is formed by mirror symmetry, and the microstructure closed cavity 20 is formed with the outer cladding 1.

[0058] Furthermore, a certain amount of air space 30 is retained between these microstructure closed cavities 20 .

[0059] like Figure 1 As shown, the complete microstructure fiber cross section is composed of 6 of the above-mentioned special-shaped anti-resonant microstructures 2, and Figure 1 At the placement angle shown, along Figure 1 The x and y directions are axisymmetric.

[0060] In this embodiment 1, the shaped antiresonant hollow-core optical fiber is surrounded by the shaped antiresonant microstructure 2 to form a circular core region 3. The shaped antiresonant hollow-core optical fiber achieves a transmission loss of less than 0.2 dB / km at 1.55 μm through this structural design.

[0061] This shaped antiresonant hollow core fiber provides a new possibility for the shape design of non-nested antiresonant hollow core fibers; in this embodiment, by setting a longer straight line segment 22 of the microstructure arc, such as Figure 1 As shown, effectively pushing the node away from the core region 3 can reduce the leakage loss along the leakage path in the direction of the line connecting the center of the core and the center of the microstructure arc closest to the core (the first arc segment 21).

[0062] Further, such as Figure 1 As shown, the radius of the first arc segment 21 closest to the fiber core is moderate, so as not to form an excessively large negative curvature. The moderate negative curvature arc reduces the power lost from the node per unit length of transmission distance.

[0063] At the same time, the introduction of the third arc segment 23 at the appropriate end can effectively reduce the coupling degree between the core mode and the mode at the gap, limit the power lost from the gap, and thus provide new possibilities for the non-nested structural design of low-loss antiresonant hollow-core optical fiber.

[0064] like Figure 3 FIG. 1 shows the simulated loss spectra of the shaped antiresonant hollow-core optical fiber of this embodiment at different wavelengths.

[0065] Specifically, such as Figure 3 As shown in the figure, the loss spectrum shows that when the microstructure has a wall thickness of 1.13um and the light guide wavelength is 1.55um, the loss is 0.19dB / km, which is less than 0.2dB / km. From 1.3um to 1.65um, the transmission loss can be maintained below 1dB / km, covering the commonly used communication band.

[0066] Specifically, such as Figure 4 FIG. 1 shows a phase distribution diagram of a quarter cross section of the fundamental mode of the shaped antiresonant hollow core optical fiber of this embodiment in the 1.55 μm band.

[0067] Because after the introduction of a longer straight line segment 22 in this embodiment, the excited gap mode is a high-order mode, and due to the introduction of the third arc segment 24, the phase of the gap mode is regulated, thereby increasing the phase oscillation of the gap mode at the leakage boundary, avoiding the radiation mode from coherently constructing more in the far field, thereby reducing the power lost from the gap.

[0068] like Figure 5 As shown in the figure on the right, the arc phase distribution along the arc segment at the gap in the left figure is shown. The phase oscillates obviously at this boundary.

[0069] Specifically, such as Figure 5 As shown, the arc length corresponding to the horizontal axis in the right figure is the black part (i.e., the gap radiation boundary) in the left figure extending from the upper left starting point, and the unit of the vertical axis phase is radian, reflecting that as the arc length extends, Figure 5 It can be seen that the phase shows a more violent oscillation, which is more in line with the effect sought.

[0070] Example 2:

[0071] In this embodiment, the substructures in each semi-microstructure outer arc segment 4 include:

[0072] The first arc segment 41, the second arc segment 42 and the third arc segment 43 are sequentially connected from the core region to the inner wall of the outer cladding.

[0073] In this embodiment, the first arc segment 41 and the second arc segment 42 are inscribed inwardly, and the second arc segment 42 and the third arc segment 43 are circumscribed inwardly.

[0074] In this embodiment, the wall thicknesses of the first arc segment 41 , the second arc segment 42 and the third arc segment 43 are the same everywhere.

[0075] In this embodiment, the curvature directions of the third arc segments 43 of different semi-microstructure outer arc segments 4 are opposite.

[0076] Specifically, in the preferred embodiment 2 of the present invention, based on a simpler method of constructing a microstructure arc, compared with the method of using four sub-structures to form a semi-microstructure outer arc segment in embodiment 1, a certain degree of simplification has been performed, and the semi-microstructure outer arc 4 is formed by using three circular arcs.

[0077] Specifically, in this embodiment 2, Figure 6 As shown, the basic substructures are: a first arc segment 41, a second arc segment 42, and a third arc segment 43. The first arc segment 41 and the second arc segment 42 are in an inscribed geometric relationship, while the second arc segment 42 and the third arc segment 43 are in an circumscribed geometric relationship.

[0078] Further, the three arc segments do not intersect each other and are kept within a reasonable spatial range.

[0079] By selecting appropriate radius and central angle parameters of the three arc segments, the design of a low-loss microstructure optical fiber can be realized.

[0080] Specifically, in the embodiment 2, as shown in the figure, Figure 7 the radius of the first arc segment 41 is 16 um, the radius of the second arc segment 42 is 256 um, and the radius of the third arc segment 43 is 17.3 um.

[0081] As shown in the figure, Figure 7 after the construction of a special-shaped anti-resonant microstructure, it is determined that the number of special-shaped anti-resonant microstructures 2 to be taken is 6, and the wall thickness of the thin wall is uniform at 1.13 um. Further, a certain air gap 30 is kept between the microstructure closed cavities and they do not contact each other. In this embodiment, the core region 3 is formed by being surrounded by the six special-shaped anti-resonant microstructures.

[0082] In this embodiment, as shown in the figure, Figure 7 the core diameter of the core region is 46.5 um, and the larger core size can make the light wave experience fewer reflections or leaks in a unit distance of transmission length.

[0083] As shown in the figure, Figure 8 is the simulation loss spectrum of the special-shaped anti-resonant hollow optical fiber taken in the embodiment 2 at different wavelengths.

[0084] Specifically, as shown in the figure, Figure 8 the loss spectrum shows that when the light guiding wavelength is 1.55 um, the loss is 0.20 dB / km under the condition that the wall thickness of the microstructure is 1.13 um. From 1.45 um to 1.65 um, 1 dB / km can be met.

[0085] Specifically, the embodiment 2 still retains the characteristic of pushing the nodes far away, as shown in the figure, Figure 6 further, by setting the inwardly recessed arc segment to squeeze the mode field in the microstructure, the phase matching condition of the core mode and the mode in the microstructure closed cavity is broken, so as to reduce the power loss of the light field from the center line of the core region and the first arc segment of the special-shaped anti-resonant microstructure in a unit transmission distance.

[0086] Further, as shown in the figure, Figure 6 the radius of the first arc segment 41 closest to the core is slightly larger, so as not to form a too large negative curvature, and the negative curvature of the moderate curvature arc inhibits the coupling degree of the core mode and the microstructure wall mode, and reduces the power loss from the node in a unit length transmission distance.

[0087] Further, as shown in the figure,Figure 7 As shown, the longer third arc segment 43 extending out occupies a considerable space at the gap, which can prevent the power from leaking out of the gap easily, and can inhibit the leakage of the fundamental mode from the gap to some extent, thereby further ensuring a lower transmission loss.

[0088] As shown, Figure 9 the profiled anti-resonance hollow core fiber of the present application adopts another profiled anti-resonance microstructure, which has the same number of substructures as the profiled anti-resonance hollow core fiber of embodiment 2, and is also connected by three arc segments, but the difference is that Figure 9 the curvature of the first arc segment 41 and the third arc segment 43 is different from the curvature in embodiment 2. Figure 6

[0089] The above is only the preferred embodiment of the present application, and does not limit the implementation and protection scope of the present application. It should be realized by those skilled in the art that any equivalent replacement and obvious changes made according to the content of the present application should be included in the protection scope of the present application.​

Claims

1. A non-nested shaped antiresonant hollow core optical fiber, characterized in that: include: A plurality of special-shaped anti-resonance microstructures are uniformly and equidistantly distributed along the inner wall of the outer cladding in a circumferential direction of the outer cladding, and all of the special-shaped anti-resonance microstructures form a core region at the center of the outer cladding; Each of the special-shaped anti-resonance microstructures and the outer cladding forms a microstructure closed cavity, and there is an air gap between adjacent microstructure closed cavities; Each of the special-shaped anti-resonant microstructures includes multiple substructures, any two adjacent substructures maintain a tangent relationship, and at least two adjacent substructures have opposite curvature directions.

2. The shaped antiresonant hollow-core optical fiber according to claim 1, characterized in that: The special-shaped anti-resonance microstructure includes two mirror-symmetrical semi-microstructure outer arc segments, and each of the semi-microstructure outer arc segments includes multiple segments of the substructures.

3. The shaped antiresonant hollow-core optical fiber according to claim 2, characterized in that: The substructures in each of the semi-microstructure outer arc segments include: A first arc segment, a straight line segment, a second arc segment and a third arc segment are sequentially connected from the core region to the inner wall of the outer cladding.

4. The shaped antiresonant hollow-core optical fiber according to claim 3, characterized in that: The first arc segment is tangent to the straight line segment, the straight line segment is tangent to the second arc segment, and the second arc segment is tangent to the third arc segment.

5. The shaped antiresonant hollow-core optical fiber according to claim 4, characterized in that: The curvature directions of the second arc segment and the third arc segment are opposite.

6. The antiresonant hollow-core optical fiber according to claim 3, wherein: The wall thicknesses of the first arc segment, the straight line segment, the second arc segment and the third arc segment are all equal.

7. The shaped antiresonant hollow-core optical fiber according to claim 2, characterized in that: The substructures in each of the semi-microstructure outer arc segments include: A first arc segment, a second arc segment and a third arc segment are sequentially connected from the core region to the inner wall of the outer cladding.

8. The shaped antiresonant hollow-core optical fiber according to claim 7, characterized in that: The first arc segment and the second arc segment are inscribed inwardly, and the second arc segment and the third arc segment are circumscribed inwardly.

9. The shaped antiresonant hollow-core optical fiber according to claim 7, characterized in that: The wall thicknesses of the first arc segment, the second arc segment and the third arc segment are equal everywhere.

10. The shaped antiresonant hollow-core optical fiber according to claim 3 or 7, characterized in that: The curvature directions of the third arc segments of different outer arc segments of the semi-microstructure are opposite.

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