Low-loss high-birefringence anti-resonance optical fiber structure and application thereof

Abstract

The invention discloses a low-loss high-birefringence anti-resonance optical fiber structure and application thereof, the structure comprises an outer cladding tube and a plurality of large circular tubes, and the large circular tubes are arranged along the inner wall of the outer cladding tube and are parallel to the axis of the outer cladding tube; a wave transmission cavity is formed outside the large circular tube in the middle of the outer cladding tube; at least one arc tube wall is arranged in the wave transmission cavity; based on the anti-resonance principle and the birefringence principle, the optical fiber has the characteristics of low loss and high birefringence. The added arc pipe wall is made of the same material as that of the large circular pipe, machining and manufacturing are facilitated, the variable adjustability is achieved, and by changing the width, the radius, the position and the like, adjustment can be conducted according to actual requirements so as to achieve different properties. The design thought of the high-birefringence anti-resonance optical fiber is simplified, the unique advantage of the low-loss anti-resonance optical fiber structure is utilized, the symmetry is destroyed through the arc pipe wall, and the high-birefringence anti-resonance optical fiber has the excellent characteristics of the low-loss anti-resonance optical fiber and meanwhile has the excellent performance of the high-birefringence optical fiber.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber technology, and in particular to a low-loss high-birefringence anti-resonance optical fiber structure and application thereof. Background Art

[0002] In the fields of optical communication, optical sensing, optical measurement, and laser processing, high birefringence optical fibers are widely used and play a vital role. Antiresonant optical fibers have important practical significance in the fields of high-precision filters, high-sensitivity sensing, low-loss optical signal transmission, narrowband filters, and high-quality factor devices. In order to meet the specific needs of a given application, optical fibers of various structures can be used to adjust the specific needs of specific scenarios. Traditional optical fibers have large signal attenuation, high dispersion during transmission, uneven refractive index, and low tensile strength and tolerance. These defects make them unable to adapt well to some optical fields. Subsequently, new optical fibers such as photonic crystal fibers, hollow-core antiresonant fibers, single-mode / multimode fibers, and filled optical fibers have been developed. Improvements have been made on traditional optical fibers and can be well adapted to different fields, but they also have their own limitations.

[0003] The unsatisfactory birefringence performance of low-loss antiresonant optical fiber has, to some extent, limited the breakthrough of optical fiber technology. Summary of the invention

[0004] In order to solve the defect that the birefringence performance of the current low-loss defect anti-resonance optical fiber structure is not ideal, the present invention proposes a low-loss high-birefringence anti-resonance optical fiber structure and its application.

[0005] The technical solution adopted by the present invention is:

[0006] The low-loss high-birefringence anti-resonance optical fiber structure includes an outer cladding tube and a plurality of large round tubes, wherein the large round tubes are arranged along the inner wall of the outer cladding tube and are parallel to the axis of the outer cladding tube; a wave transmission cavity is formed outside the large round tube in the middle of the outer cladding tube;

[0007] The wave transmission cavity has at least one arc tube wall; the arc tube wall is a cylinder, parallel to the large circular tube, and the two sides of the arc tube wall are connected to the outer wall of the large circular tube;

[0008] The cross section of the arc tube wall is an arc segment surface, and the convex surface faces the wave transmission cavity.

[0009] When working, by adding at least one arc tube wall, the internal symmetry of the low-loss anti-resonant optical fiber structure is destroyed, so that it has high birefringence performance;

[0010] Preferably, a small circular tube is provided inside the large circular tube, so as to further optimize the anti-resonance optical fiber structure.

[0011] Preferably, the wave transmission cavity has two arc tube walls, which are symmetrically arranged on a large circular tube on both sides of the wave transmission cavity.

[0012] Preferably, the arc tube wall is a semicircular tube.

[0013] Preferably, the arc tube wall parameters are r=1.1 mm, t1=0.12 mm.

[0014] Preferably, the wall thickness of the arc tube wall is different from the wall thickness of the large circular tube.

[0015] Preferably, the arc tube wall is made of the same material as the large round tube and is integrally formed with the large round tube.

[0016] Preferably, the low-loss high-birefringence anti-resonance optical fiber structure is made of Topas.

[0017] Preferably, the wave transmission cavity has 1 or 3 arc tube walls, which are arranged one by one on the large circular tubes around the wave transmission cavity.

[0018] The present invention also proposes the application of the low-loss high-birefringence anti-resonance optical fiber structure in wave transmission including the terahertz frequency band.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present application has low-loss and high-birefringence characteristics based on the anti-resonance principle and the birefringence principle. The inventive concept of the present application is universal, and the existing low-loss anti-resonance structure can be improved to increase its birefringence characteristics. The arc tube wall structure added in the present application uses the same material as the low-loss basis, which is conducive to processing and manufacturing, and the structure in the present application is highly adjustable. By changing its width, radius, position, etc., it can be adjusted according to actual needs to achieve different performance. The concept of the present application simplifies the design process and ideas of traditional high-birefringence anti-resonance optical fibers. The present invention utilizes the unique advantages of the low-loss structure and the arc tube wall structure to destroy the symmetry. It has the excellent characteristics of low-loss anti-resonance optical fibers and the excellent performance of high-birefringence optical fibers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is described in detail below with reference to the embodiments and accompanying drawings, wherein:

[0022] Figure 1 is a cross-sectional schematic diagram of an embodiment of a low-loss high-birefringence anti-resonant optical fiber structure;

[0023] Figure 2 It is a three-dimensional schematic diagram of an embodiment of a low-loss high-birefringence anti-resonant optical fiber structure;

[0024] Figure 3is a wave transmission schematic diagram of an embodiment of a low-loss high-birefringence anti-resonant optical fiber structure;

[0025] Figure 4 is a loss calculation diagram of an embodiment of a low-loss high-birefringence anti-resonant optical fiber structure, wherein r is a variable parameter;

[0026] Figure 5 is a loss calculation diagram of an embodiment of a low-loss high-birefringence anti-resonant optical fiber structure in which t1 is a variable parameter;

[0027] Figure 6 It is a structural schematic diagram of another embodiment of a low-loss high-birefringence anti-resonant optical fiber structure;

[0028] Figure 7 yes Figure 6 Performance calculation graph in the example;

[0029] Figure 8 yes Figure 6 Loss calculation diagram in the example;

[0030] Fig. 9 Figures 9a and 9b are calculation diagrams of wave transmission performance in the bands around 1 THz and 0.7-1.12 THz;

[0031] Among them: 1. Outer cladding tube; 2. Large circular tube; 3. Wave transmission cavity; 4. Arc tube wall; 5. Small circular tube. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar components or components with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0033] like Figure 1-2 A low-loss high-birefringence anti-resonant optical fiber structure comprises an outer cladding tube 1 and a plurality of large circular tubes 2. In some embodiments, the number of the large circular tubes 2 is 6 and they are centrally symmetrically arranged in the outer cladding tube 1. The large circular tubes 2 are arranged along the inner wall of the outer cladding tube 1, and a wave transmission cavity 3 is formed between the large circular tubes 2. The wave transmission cavity 3 has at least one arc tube wall 4. Both ends of the arc tube wall 4 are connected to the outer wall of the large circular tube 2, the axis of the arc tube wall 4 is parallel to the axis of the large circular tube, and the convex surface of the arc tube wall 4 faces the wave transmission cavity 3.

[0034] In some embodiments, a small circular tube 5 is provided inside the large circular tube 2, and the outer wall of the small circular tube 5 abuts against the tube wall of the large circular tube 2 on the side away from the wave transmission cavity 3; in some embodiments, two arc tube walls 4 are provided inside the wave transmission cavity 3, and are symmetrically arranged on the large circular tube 2 on both sides of the wave transmission cavity 3. In some embodiments, the arc tube wall 4 is a semicircular tube; in some embodiments, the wall thickness of the arc tube wall 4 is different from the wall thickness of the large circular tube 2. In some embodiments, the arc tube wall 4 is made of the same material as the large circular tube 2, and is integrally formed with the large circular tube 2, and Topas is selected as the material.

[0035] In some embodiments, the wave transmission cavity 3 has one arc tube wall, which is arranged one by one on the large circular tubes 2 around the wave transmission cavity 3; in some embodiments, the wave transmission cavity 3 has three arc tube walls, which are arranged one by one on the large circular tubes 2 around the wave transmission cavity 3;

[0036] In some embodiments, Topas is used as the material, and a semicircular arc tube wall structure is added to the low-loss model, such as Figure 1 As shown, X is horizontal and Y is vertical; the shaded part is the optical fiber structure, the material is Topas, and the blank is air;

[0037] The simulation calculation was performed using COMSOL software, and the constant refractive index n = 1.5258 was obtained in the range of 0.1THz-1.5THz. The Topas material loss is linearly proportional to the frequency, and can be approximated as αmat = 0.36(f-0.4) + 0.06 in the range of 0.2-1.6THz, where f is in THz and αmat is in dB / cm. In some embodiments, the following equations are used to calculate the constraint loss αcl, the effective material loss αEML, and the material constraint power fraction ηx:

[0038]

[0039] In terahertz fibers, the main types of losses are material absorption losses and confinement losses, which are added together to calculate the total transmission loss. The fraction of power (η) confined in different regions, such as air or fiber material, is used to quantify the overlap between light and material. The effective material loss (αEML), defined as the product of the material loss (αmat) and the fraction of power in the background material (ηm). In the above equation, ε0 and μ0 are the dielectric constant and magnetic permeability of vacuum, respectively. In some embodiments, the numerator integration is performed over the solid material region of Topas, and the denominator integration is performed over all regions, material regions, and pore regions, because air is considered transparent in the terahertz band. In some embodiments, Sz is defined as the Poynting vector in the propagation direction, denoted as Sz=Re(E×H*)z, where E is the electric field component and H is the magnetic field component. In some embodiments, the fraction of power confined in the background material (Topas) is given by ηm.

[0040] After calculation optimization, Figure 3-5 The optimal dimensions of the arc tube wall of this structure are r = 1.1mm, t1 = 0.12mm, Dc = 3mm, D1 = 2.6mm, D2 = 1.4mm, t = 0.09mm. The following data is based on the optimal ratio of the model, maintaining 10 in the 0.72-1.0THz frequency band -3 For birefringence above level 1, the loss in both polarization directions is less than 5dB / m.

[0041] In some embodiments, the above structure is applied to other low-loss models, and the diameter of the round rod in the nested-rod model is 0.4 mm, and the thickness of the partition in the straightbar model is t. Figure 6 As shown; used in this size to test their related performance still maintains high birefringence and low loss performance; as Figure 7 As shown; when applying other low-loss models, due to differences in materials and structures, it may be necessary to readjust the radius and thickness of the arc tube wall to achieve the best ratio.

[0042] This structure can reach about 2×10 -3 The birefringence is stable at 10 in the 0.7-1.12THz band. -3 Birefringence above the level, keeping the loss below 5dB / m, the minimum bending radius can reach 0.3m; Fig. 9 As shown, the simulation verifies that the present application also has good tolerance to manufacturing errors, such as Figure 4 After simulation, the application structure was used in two other low-loss structures and still achieved low-loss birefringence performance.

[0043] In summary: (1) The present application only requires a single material for manufacturing, thus avoiding the difficulty in manufacturing the preform rod caused by double materials, and the possible breakage problem due to different melting points during drawing.

[0044] (2) The present application has good high birefringence performance and low loss, and has good performance.

[0045] (3) The present application can be directly superimposed on any hollow-core low-loss antiresonant tube to increase its birefringence performance, has universal applicability, and simplifies the design process of high-birefringence low-loss antiresonant optical fiber.

[0046] (4) The stacked non-uniform thickness casing structure of the present application has high mechanical strength and good tolerance to manufacturing errors in the manufacturing of preform rods and wire drawing processes, such as Figure 8 As shown, it has high mechanical strength.

[0047] In the description of this specification, if the terms "embodiment one", "this embodiment", "in an embodiment" and the like appear, it means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in the invention or at least one embodiment or example of the invention. 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 may be combined in any one or more embodiments or examples in an appropriate manner.

[0048] In the description of this specification, the terms "connect", "install", "fix", "set", "have", etc. are all understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0049] In the description of this specification, relational terms such as "first" and "second" are used only 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 "comprises", "comprising" 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. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0050] The above description of the embodiments is to facilitate ordinary technicians in the technical field to understand and apply the technology of this case. People familiar with the technology in this field can obviously easily make various modifications to these examples and apply the general principles described here to other embodiments without creative work. Therefore, this case is not limited to the above embodiments. Modifications to the following situations should all be within the scope of protection of this case: ① A new technical solution implemented based on the technical solution of the present invention and combined with existing common knowledge, the technical effect produced by the new technical solution does not exceed the technical effect of the present invention; ② The equivalent replacement of some features of the technical solution of the present invention by using known technology, the technical effect produced is the same as the technical effect of the present invention; ③ The technical solution of the present invention can be expanded, and the substantive content of the expanded technical solution does not exceed the technical solution of the present invention; ④ The equivalent transformation made by using the contents of the description and drawings of the present invention is directly or indirectly applied to other related technical fields.

Claims

1. Low-loss high-birefringence anti-resonant optical fiber structure, characterized in that: It includes an outer cladding tube and a plurality of large round tubes, wherein the large round tubes are arranged along the inner wall of the outer cladding tube and are parallel to the axis of the outer cladding tube; a wave transmission cavity is formed outside the large round tube in the middle of the outer cladding tube; The wave transmission cavity has at least one arc tube wall; the arc tube wall is a cylinder, parallel to the large circular tube, and the two sides of the arc tube wall are connected to the outer wall of the large circular tube; The cross section of the arc tube wall is an arc segment surface, and the convex surface faces the wave transmission cavity.

2. The low-loss high-birefringence anti-resonant optical fiber structure according to claim 1, characterized in that: A small round tube is arranged inside the large round tube.

3. The low-loss high-birefringence anti-resonant optical fiber structure according to claim 1, characterized in that: The wave transmission cavity is provided with two arc tube walls, which are symmetrically arranged on the large circular tubes on both sides of the wave transmission cavity.

4. The low-loss high-birefringence anti-resonance optical fiber structure according to claim 3, characterized in that: The arc tube wall is a semicircular tube.

5. The low-loss high-birefringence anti-resonance optical fiber structure according to claim 4, characterized in that: The parameters of the arc tube wall are r=1.1 mm, t1=0.12 mm.

6. The low-loss high-birefringence anti-resonant optical fiber structure according to claim 1, characterized in that: The wall thickness of the arc tube wall is different from the wall thickness of the large circular tube.

7. The low-loss high-birefringence anti-resonant optical fiber structure according to claim 1, characterized in that: The arc tube wall is made of the same material as the large round tube and is integrally formed with the large round tube.

8. The low-loss high-birefringence anti-resonant optical fiber structure according to claim 7, characterized in that: The low-loss high-birefringence anti-resonant fiber structure is made of Topas.

9. The low-loss high-birefringence anti-resonant optical fiber structure according to claim 1, characterized in that: The wave transmission cavity is provided with one or three arc tube walls, which are arranged one by one on the large circular tubes around the wave transmission cavity.

10. An application of the low-loss high-birefringence anti-resonant optical fiber structure according to any one of claims 1 to 9 in wave transmission including the terahertz frequency band.

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