Hollow-core optical fiber with low optical loss

Abstract

The utility model provides a hollow-core optical fiber with low optical loss, which relates to the technical field of optical fibers, and comprises an outer cladding, a first capillary layer and a second capillary layer, the connecting line of the center of a hollow core area defined by the second capillary tube layer and the center of each second capillary tube penetrates through the gap between the two first capillary tubes, and the connecting line of the center of the hollow core area and the center of each first capillary tube penetrates through the gap between the two second capillary tubes. According to the technical scheme of the utility model, through the structural arrangement of the first capillary tubes and the second capillary tubes, the optical fibers on the connecting line of the center of the hollow core area and the center of the second capillary tubes are constrained by the gaps between the first capillary tubes, so that the optical loss in the high-loss direction is reduced. At least one gap exists in the low-loss direction and the high-loss direction for effectively constraining light and reducing the confinement loss of the optical fiber; moreover, the light leakage distance can be increased, and the light loss is further reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fibers, in particular to a hollow-core optical fiber with low optical loss. Background Art

[0002] Since the publication of a groundbreaking paper by British Chinese scientist Dr. Charles Kao in 1966, fiber optic technology has achieved great success in fields such as optical communications, and has had a broad and far-reaching impact on human society.

[0003] Compared with traditional solid-core optical fibers, which have only approached the loss limit after half a century of attenuation, the rapid progress made in reducing the loss of hollow-core antiresonant optical fibers in the past few years has attracted the attention of researchers around the world. However, the ultra-low loss performance of current hollow-core antiresonant optical fibers is still limited when used for long-distance transmission, and has not achieved a relatively ideal effect. Utility Model Content

[0004] In view of the problems existing in the prior art, the utility model provides a hollow-core optical fiber with low optical loss, comprising:

[0005] The interior of the outer cladding includes a first capillary layer and a second capillary layer;

[0006] The first capillary layer includes a plurality of first capillaries, and the second capillary layer includes a plurality of second capillaries;

[0007] A line connecting the center of the hollow area surrounded by the second capillary layer and the center of each second capillary passes through the gap between two first capillaries respectively, and a line connecting the center of the hollow area and the center of each first capillary passes through the gap between two second capillaries respectively.

[0008] Preferably, the second capillary layer is located between the outer cladding layer and the first capillary layer;

[0009] Each of the first capillaries is located between two of the second capillaries.

[0010] Preferably, the contact wall of the first capillary and the corresponding second capillary continuously forms an unclosed capillary.

[0011] Preferably, a third capillary layer is further included, wherein the third capillary layer includes a plurality of third capillaries, each of the third capillaries corresponds to one of the second capillaries, and the third capillaries are located inside the second capillaries.

[0012] Preferably, the outer wall of the third capillary is tangent to the corresponding inner wall of the second capillary, and the tangent point between the third capillary and the second capillary is the same as the connection point between the second capillary and the outer cladding.

[0013] Preferably, an inner cladding layer is provided between the first capillary layer and the second capillary layer, and the inner cladding layer surrounds the first capillary layer.

[0014] Preferably, each of the first capillaries in the first capillary layer is located inside the second capillary;

[0015] Each of the second capillaries includes two of the first capillaries, and a gap between the two capillaries is located on a line connecting the center of the hollow region and the center of the second capillary.

[0016] Preferably, a plurality of fourth capillaries are further included, each corresponding to each of the second capillaries, each of the fourth capillaries is located between the inner wall of the second capillary and the outer wall of the corresponding first capillary, and the fourth capillary is tangent to the inner wall of the corresponding second capillary.

[0017] Preferably, the tangent point of the fourth capillary and the second capillary is the same as the connection point of the second capillary and the outer cladding.

[0018] Preferably, the width of each of the gaps is in the range of 20 nanometers to 5 micrometers.

[0019] The above technical solution has the following advantages or beneficial effects: through the structural arrangement of the first capillary and the second capillary, the light on the line connecting the center of the hollow core area and the center of the second capillary is bound by the gap between the first capillaries, thereby reducing the light loss in the high-loss direction, so that there is at least one gap in both the low-loss direction and the high-loss direction to effectively bind the light and reduce the limiting loss of the optical fiber; and it can also increase the distance of light leakage from the light passing through the capillary wall to the outer cladding, thereby further reducing the light loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram showing the relationship between light leakage direction and light loss;

[0021] Figure 2 It is a schematic diagram of the structure of the hollow core optical fiber in the first embodiment;

[0022] Figure 3 A new anti-resonance layer structure is proposed;

[0023] Figure 4 It is a schematic diagram of the structure of the hollow core optical fiber in the second embodiment;

[0024] Figure 5 Schematic diagram of the structure of the hollow core optical fiber in Example 3;

[0025] Figure 6 Schematic diagram of the structure of the hollow core optical fiber in the fourth embodiment;

[0026] Figure 7 Schematic diagram of the structure of the hollow core optical fiber in the fifth embodiment;

[0027] Figure 8 Schematic diagram of the structure of the hollow core optical fiber in Example 6. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The present invention is not limited to the implementation mode, and other implementation modes may also fall within the scope of the present invention as long as they meet the purpose of the present invention.

[0029] In a preferred embodiment of the present utility model, based on the above problems existing in the prior art, a hollow core optical fiber with low optical loss is provided, comprising:

[0030] The interior of the outer cladding 1 includes a first capillary layer and a second capillary layer;

[0031] The first capillary layer includes a plurality of first capillaries 2, and the second capillary layer includes a plurality of second capillaries 3;

[0032] The lines connecting the center of the hollow area surrounded by the second capillary layer and the center of each second capillary 3 pass through the gap between the two first capillaries 2 , and the lines connecting the center of the hollow area and the center of each first capillary 2 pass through the gap between the two second capillaries 3 .

[0033] Specifically, refer to Figure 1 At present, the nodeless anti-resonance optical fiber has clarified the following two points from theoretical research:

[0034] (1) The smaller the gap between the capillaries of the anti-resonance structure, the smaller the limiting loss. The direction of the gap radiating outward from the center of the structure is the low-loss direction L of this type of structure, while the direction of the line connecting the center point of the structure and the center point of the capillary, or the direction perpendicular to the anti-resonance wall, is the high-loss direction H.

[0035] (2) The longer the distance LD from the capillary wall surrounding the central core area to the quartz outer cladding, the longer the light leakage distance and the lower the loss.

[0036] In this embodiment, by providing the first capillary layer and the second capillary layer, there is a gap on the line connecting the center of the enclosed hollow area and the center of each first capillary 2 and the line connecting the center of the hollow area and the center of each second capillary 3 to bind the light and reduce the light loss. And referring to the structure in the subsequent embodiments, by arranging the positions of the first capillary layer and the second capillary layer, the light leakage distance is increased, and the light loss is further reduced.

[0037] Embodiment 1:

[0038] In this embodiment, the second capillary layer is located between the outer cladding layer 1 and the first capillary layer; each first capillary 2 is located between two second capillaries 3 .

[0039] like Figure 2 As shown, the first capillary layer and the second capillary layer in this embodiment include corresponding numbers of capillaries, preferably six in this embodiment;

[0040] The outer cladding layer 1, the second capillary layer and the first capillary layer are arranged in sequence from outside to inside, forming a hollow core area in the center;

[0041] Each first capillary tube 2 is in contact with two second capillaries 3 and is located on a line connecting the center of the hollow region and the gap between the second capillaries 3 .

[0042] Through Figure 2 The arrangement of the capillaries in FIG. 1 shows that, from the low-loss direction L, the light passes through the capillary wall of the first capillary 2 and is then bounded by the gap between the second capillary 3, and finally reaches the outer cladding, increasing the distance from the capillary wall to the quartz outer cladding (C increases to D), which reduces the optical loss.

[0043] From the perspective of high loss direction, the optical fiber is first bounded by the gap between the first capillary 2, then passes through the wall of the second capillary and finally reaches the outer cladding of quartz. Adding a gap to bind the optical fiber in the high loss direction also increases the distance from the capillary wall to the outer cladding of quartz (A increases from B), which further reduces the optical loss.

[0044] Embodiment 2:

[0045] In this embodiment, based on the hollow core optical fiber in the first embodiment, the contact wall of the first capillary tube and the corresponding second capillary tube are continuously formed into an unclosed capillary tube.

[0046] Specifically, Figure 3 As shown in FIG. 1 , a new anti-resonance layer structure is designed, which connects the capillary walls of the first capillary 2 and the second capillary 3 together, so that the first capillary 2 and the second capillary 3 are no longer closed tubular structures. Figure 4 As shown in the figure, it can be seen that the capillary walls of the first capillary and the second capillary form a continuous anti-resonance layer structure.

[0047] The hollow-core optical fiber structure in this embodiment can achieve the same effect as that in the first embodiment, and because the capillary walls are connected and firstly joined, there is one less layer of capillary wall in both the high-loss direction H and the low-loss direction L compared to the first embodiment, and the effect of reducing optical loss can be further improved on the basis of the first embodiment.

[0048] Embodiment three:

[0049] In this embodiment, on the basis of the second embodiment, a third capillary layer is further included, and the third capillary layer includes a plurality of third capillaries 4, each of the third capillaries 4 corresponds to a second capillary 2, and the third capillary 4 is located inside the second capillary 3. In this embodiment, the outer wall of the third capillary 4 is tangent to the inner wall of the corresponding second capillary 3, and the tangent point between the third capillary 4 and the second capillary 3 is the same as the connection point between the second capillary 3 and the outer cladding 1.

[0050] Specifically, Figure 5 As shown, this embodiment adds a plurality of third capillaries 4 on the basis of the second embodiment, which are respectively located on the inner wall of each second capillary 3 and are used to divide the mode field of the second capillary 3 .

[0051] The mode field in an optical fiber is an important concept that involves the distribution of electric and magnetic fields when light propagates in an optical fiber. The mode field refers to the distribution of electric and magnetic fields when light propagates in an optical fiber, and its size determines the transmission characteristics and mode characteristics of light in the optical fiber. The mode field diameter is the distribution state of the fundamental mode light in the core region of a single-mode optical fiber. Specifically, the mode field diameter is defined by the maximum distance between two points where the light intensity is reduced to 1 / (e^2) of the maximum light intensity on the axis. The size and shape of the mode field have an important influence on the transmission characteristics of the optical fiber. By providing a third capillary 4 in the second capillary 3, the mode field of the second capillary 3 can be split. In high-power transmission, nonlinear effects such as stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) will lead to increased optical loss. By splitting the mode field and optimizing the mode field distribution, the influence of nonlinear effects can be reduced and the loss can be reduced. Improve bending performance: When a large mode field optical fiber is bent, the mode field may change significantly, resulting in increased optical loss. By splitting the mode field and optimizing the design, the bending performance of the optical fiber can be improved, and low loss can be maintained even in a bent state. This is beneficial to further reduce light loss.

[0052] Embodiment 4:

[0053] In this embodiment, based on the first embodiment, an inner cladding layer 5 is further included between the first capillary layer 2 and the second capillary layer 3 , and the inner cladding layer 5 surrounds the first capillary layer 2 .

[0054] Specifically, Figure 6As shown, this embodiment adds an inner cladding layer 5 on the basis of the first embodiment, which can achieve the effect of the first embodiment and help to increase the stability of the overall structure.

[0055] Embodiment five:

[0056] In this embodiment, the first capillary layer, the second capillary layer and the outer cladding layer in the first embodiment are included, but the difference from the first embodiment is that each first capillary 2 in the first capillary layer in this embodiment is located inside the second capillary 3;

[0057] Each second capillary tube 3 includes two first capillaries 2 , and the gap between the two capillaries 2 is located on a line connecting the center of the hollow region and the center of the second capillary tube 3 .

[0058] Specifically, Figure 7 As shown, the first capillary layer, the second capillary layer and the outer cladding in this embodiment are no longer arranged from the inside to the outside, but the first capillary 2 is placed in the second capillary 3. As an alternative to the first embodiment, this embodiment has no obvious difference from the traditional hollow-core optical fiber in the low-loss direction L, but in the high-loss direction H, the effect of reducing optical loss by adding a "gap" to bind light in the high-loss direction H in the first embodiment can still be achieved. And the difficulty of the manufacturing process will also be reduced.

[0059] Embodiment six:

[0060] In this embodiment, based on the fifth embodiment, a plurality of fourth capillaries 6 are further included, corresponding to each second capillary 3 , each fourth capillary 6 is located between the inner wall of the second capillary 3 and the outer wall of the corresponding first capillary 2 , and the fourth capillary 6 is tangent to the inner wall of the corresponding second capillary 3 .

[0061] In this embodiment, the tangent point between the fourth capillary 6 and the second capillary 3 is the same as the connection point between the second capillary 3 and the outer cladding 1 .

[0062] Specifically, the structure in this embodiment is as follows Figure 8 As shown, it can be seen that the difference from the structure in Example 5 is that multiple fourth capillaries 6 are added, so the hollow-core optical fiber in this embodiment can also achieve the effect of the hollow-core optical fiber in Example 5, and the effect of the fourth capillary 6 is the same as that of the third capillary 5 in Example 3, and can also split the mode field to reduce optical loss.

[0063] In all the aforementioned embodiments, the width of each gap ranges from 20 nanometers to 5 microns. The material of the hollow core optical fiber can be any material having the properties of an optical waveguide, a terahertz waveguide, a microwave guide, etc., including but not limited to glass materials: fused silica glass, fluoride glass, chalcogenide glass, soft glass, etc.; including but not limited to polymer materials: PMMA, PC, PVC, etc.; including but not limited to metal materials: gold, silver, copper, iron, aluminum, etc.; including but not limited to crystal materials: diamond, aluminum oxide, silicon carbide, etc.;

[0064] In the hollow core optical fiber of the present invention, the first capillary layer and the second capillary layer form an anti-resonance layer structure. The anti-resonance layer can be the capillary wall of each capillary, and can be the thickness of the curved shape (ie, Figure 3 The wall of the structure in the figure) may be a positive curvature annular structure wall (ie, Figure 4 The thickness of the anti-resonance layer wall is 10-5000 nanometers; when conducting terahertz waves or electromagnetic waves with longer wavelengths, the thickness of the anti-resonance layer wall is 5-100 micrometers;

[0065] The thickness of the all-solid outer cladding 1 is in the range of 10-500 microns.

[0066] Hollow-core optical fiber has a very high nonlinear tolerance. Even when the loss is higher than that of standard quartz single-mode optical fiber, its low nonlinearity is sufficient to transmit optical signals at a rate of 6.4Tbit / s over a distance of 1200km. Therefore, by changing the capillary structure and arrangement position of the anti-resonance layer in the hollow-core optical fiber in the utility model, the ultra-low loss performance of the hollow-core optical fiber can be significantly improved. Such a hollow-core optical fiber has the performance advantages of long-distance signal transmission and low loss at the same time.

[0067] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of this specification and illustrations should be included in the protection scope of the present invention.

Claims

1. A hollow core optical fiber with low optical loss, characterized in that: include: The interior of the outer cladding includes a first capillary layer and a second capillary layer; The first capillary layer includes a plurality of first capillaries, and the second capillary layer includes a plurality of second capillaries; A line connecting the center of the hollow area surrounded by the second capillary layer and the center of each second capillary passes through the gap between two first capillaries respectively, and a line connecting the center of the hollow area and the center of each first capillary passes through the gap between two second capillaries respectively.

2. The hollow core optical fiber according to claim 1, characterized in that: The second capillary layer is located between the outer cladding layer and the first capillary layer; Each of the first capillaries is located between two of the second capillaries.

3. The hollow core optical fiber according to claim 2, characterized in that: The capillary walls of the first capillary and the corresponding second capillary are continuously formed into an open capillary.

4. The hollow core optical fiber according to claim 1, characterized in that: The invention also comprises a third capillary layer, wherein the third capillary layer comprises a plurality of third capillaries, each of the third capillaries corresponds to one of the second capillaries, and the third capillaries are located inside the second capillaries.

5. The hollow core optical fiber according to claim 4, characterized in that: The outer wall of the third capillary is tangent to the corresponding inner wall of the second capillary, and the tangent point between the third capillary and the second capillary is the same as the connection point between the second capillary and the outer cladding.

6. The hollow core optical fiber according to claim 2, characterized in that: An inner cladding layer is further included between the first capillary layer and the second capillary layer, and the inner cladding layer surrounds the first capillary layer.

7. The hollow core optical fiber according to claim 1, characterized in that: Each of the first capillaries in the first capillary layer is located inside the second capillary; Each of the second capillaries includes two of the first capillaries, and a gap between the two capillaries is located on a line connecting the center of the hollow region and the center of the second capillary.

8. The hollow core optical fiber according to claim 7, characterized in that: It also includes a plurality of fourth capillaries corresponding to the second capillaries respectively, each of the fourth capillaries is located between the inner wall of the second capillary and the outer wall of the corresponding first capillary, and the fourth capillary is tangent to the inner wall of the corresponding second capillary.

9. The hollow core optical fiber according to claim 8, characterized in that: The tangent point of the fourth capillary and the second capillary is the same as the connection point of the second capillary and the outer cladding.

10. The hollow core optical fiber according to claim 1, characterized in that: The width of each of the gaps ranges from 20 nanometers to 5 micrometers.

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