Photonic crystal fiber based on negative Poisson's ratio unit cell structure

Abstract

The invention belongs to the technical field of optical fiber sensing, and particularly relates to a photonic crystal fiber based on a negative poisson ratio unit cell structure. The photonic crystal fiber comprises a cladding and a fiber core; the optical fiber is characterized in that a unit cell structure with a negative Poisson's ratio effect is arranged in the cladding; the unit cell structure comprises a plurality of air hole layers; each air hole layer comprises a plurality of elliptical air holes arranged around the fiber core, and two adjacent elliptical air holes in each air hole layer are orthogonally arranged; and the two adjacent elliptical air holes in the two adjacent air hole layers are orthogonally arranged. According to the photonic crystal fiber provided by the invention, the effective Poisson's ratio of the overall structure is reduced by utilizing the auxetic effect of the negative Poisson's ratio unit cells, so that the interference resistance of the fiber is enhanced under the action of external force, the energy absorption and shock absorption effects can be realized only through simple pore shape design and arrangement, and the stress interference resistance of the fiber is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to a photonic crystal optical fiber based on a negative Poisson's ratio unit cell structure. Background Art

[0002] Photonic crystal fiber can achieve rich functions by changing the geometric characteristics of the air holes on the cross section, that is, the size, position and arrangement of the holes. Compared with traditional optical fibers, it has many excellent characteristics, such as high birefringence, non-cutoff single-mode transmission in a large band, adjustable dispersion characteristics, etc. Photonic crystal fiber also has a low effective mode refractive index, which makes it have excellent resistance to temperature and magnetic field interference. Therefore, studying the transmission characteristics of photonic crystal fiber and optimizing its performance is of great significance to improving the environmental adaptability of optical fiber sensing systems.

[0003] One of the most important issues in the research and application of photonic crystal fibers is loss control under stress loads. In the complex stress environment of fiber optic sensing systems, due to the presence of air holes inside the structure, the mechanical strength of photonic crystal fibers is much smaller than that of solid fibers, making photonic crystal fibers more sensitive to external stress. The fiber deformation caused by stress loads weakens the photonic crystal fiber's ability to control the fundamental mode, resulting in additional losses, which poses a great challenge to the stable transmission of optical signals in the optical fiber.

[0004] Most of the existing studies on photonic crystal fiber loss are approximate calculations based on the refractive index analysis model, and rarely consider the stress conditions of the unit cell structure and the mechanical response of the fiber to external stress loads under the condition of pore deformation. However, this is a factor that cannot be ignored in the loss analysis of photonic crystal fibers and is more in line with the actual situation.

[0005] In order to make the photonic crystal fiber meet the requirements of optical performance parameters and resist the loss caused by stress, the existing solutions are mostly focused on the design of the photonic crystal fiber pores and the application of the bending loss equivalent model. Flexible pore design is indeed the advantage of photonic crystal fiber, but the overly complex pore structure and arrangement designed to optimize the optical performance parameters have high process requirements, which greatly increases the difficulty of fiber preparation. At the same time, this method can only meet specific requirements and has poor versatility. For the bending loss equivalent model, the parameter calculation of the photonic crystal fiber in the bending state is approximated based on the angle of the refractive index distribution, and the influence of the deformation of the pores on the transmission performance of the optical fiber is not considered. This is not in line with the actual situation. The design method obtained by the bending loss model can only be used as a reference, and it is difficult to accurately evaluate the parameters.

[0006] The existing photonic crystal fiber design scheme has the following main shortcomings:

[0007] (1) The existing photonic crystal fiber design method uses the shape and arrangement of air holes to optimize the parameters of photonic crystal fibers. However, this method can only perform structural design based on certain specific parameter requirements. At the same time, the complex shape and arrangement of air holes greatly increase the difficulty of preparation and make it difficult to apply in practice.

[0008] (2) The existing optical analysis of photonic crystal fibers under stress loads uses an approximate model based on the refractive index distribution, which does not take into account the pore deformation under stress. This makes the model only usable for approximate analysis and difficult to accurately evaluate parameters.

[0009] (3) Research on losses in photonic crystal fiber applications focuses on losses caused by bending. In fact, in the stress environment of optical fiber sensing systems, the stress interference experienced by photonic crystal fibers is more complex.

[0010] (4) The current research on stress interference of photonic crystal fibers does not consider the impact of the deformation of the pores on the fiber, which is different from the actual situation of the fiber.

[0011] The negative Poisson's ratio effect refers to the phenomenon that when a structure is stretched in one direction, it will expand in the other direction within the elastic range, that is, the tensile effect, which indicates that the material can present different mechanical responses when subjected to external forces. The negative Poisson's ratio structure is a porous structure with a negative Poisson's ratio effect. When subjected to external stress loads, the material perpendicular to the load direction will gather toward the loaded part. This unique indentation resistance performance enables it to effectively resist the interference of external stress loads and has excellent impact resistance, energy absorption and vibration isolation capabilities. Summary of the invention

[0012] In view of the above technical problems, the present invention provides a photonic crystal fiber based on a negative Poisson's ratio unit cell structure. The photonic crystal fiber provided by the present invention reduces the effective Poisson's ratio of the overall structure by utilizing the tensile expansion effect of the negative Poisson's ratio unit cell, so that the ability of the optical fiber to resist interference is enhanced under the action of external forces, and energy and shock absorption can be achieved with simple pore shape design and arrangement, thereby improving the ability of the optical fiber to resist stress interference.

[0013] The present invention is achieved through the following technical solutions:

[0014] A photonic crystal fiber based on a negative Poisson's ratio unit cell structure, the photonic crystal fiber comprising a cladding and a core; a unit cell structure having a negative Poisson's ratio effect is arranged in the cladding;

[0015] The unit cell structure comprises a plurality of pore layers; each pore layer comprises a plurality of elliptical pores arranged around the fiber core, two adjacent elliptical pores in each pore layer are arranged orthogonally; and two adjacent elliptical pores in two adjacent pore layers are arranged orthogonally.

[0016] Furthermore, all elliptical pores in the unit cell structure have the same size parameters; the cross section of the elliptical pore is an ellipse, the major axis radius of the ellipse is 1.5 μm to 2.5 μm, and the minor axis radius is 0.5 μm to 1.4 μm.

[0017] Further, the distance between two adjacent elliptical pores in adjacent pore layers is equal to the distance between two adjacent elliptical pores in each pore layer.

[0018] Furthermore, the spacing is 4.5 μm to 7 μm.

[0019] Furthermore, the unit cell structure includes 4 to 8 pore layers.

[0020] Furthermore, the Poisson's ratio of the overall structure of the photonic crystal fiber has a value ranging from 0.1071 to 0.1904.

[0021] Furthermore, the photonic crystal fiber is a total internal reflection photonic crystal fiber.

[0022] Beneficial technical effects of the present invention:

[0023] The photonic crystal fiber provided by the present invention reduces the effective Poisson's ratio of the overall structure by utilizing the tensile expansion effect of the negative Poisson's ratio unit cell, so that the ability of the fiber to resist interference is enhanced under the action of external forces. Energy and shock absorption effects can be achieved with simple pore shape design and arrangement, thereby improving the ability of the fiber to resist stress interference.

[0024] The photonic crystal fiber provided by the present invention provides a combination of parameters such as the arrangement of pores, pore spacing, pore shape, and pore size. The optical parameters and mechanical properties of the photonic crystal fiber can be improved through the design of the pores. At the same time, the arrangement of the proposed negative Poisson's ratio unit cell structure can be used as a general solution for the cladding structure of the photonic crystal fiber. The photonic crystal fiber provided by the present invention can effectively improve the anti-stress interference ability of the photonic crystal fiber and improve the performance of the optical fiber sensing system.

[0025] The photonic crystal fiber provided by the present invention has the advantages of good versatility and strong anti-interference ability, etc. It can solve the problem of stress interference of photonic crystal fiber in applications such as optical fiber sensing, improve the anti-interference ability of the system, and has strong application value.

[0026] Compared with a photonic crystal fiber with a circular air hole, the loss of the photonic crystal fiber provided by the present invention is reduced from 5.45E-3 to 2.33E-3 when subjected to a 4.6 μm cross-sectional compression; the loss when subjected to a 2g impact load is reduced from 8.93E-2 to 5.08E-2. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1Schematic diagram of a cross-section of a unit cell structure having a negative Poisson's ratio effect in an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of a stress load application method in an embodiment of the present invention;

[0029] Figure 3 The results of the effect of compression on the Poisson's ratio of the optical fiber structure in the embodiment of the present invention;

[0030] Figure 4 The results of the influence of compression on the additional limiting loss of three optical fiber structures in the embodiment of the present invention;

[0031] Figure 5 The results of the impact amplitude on the Poisson's ratio of the optical fiber structure in the embodiment of the present invention;

[0032] Figure 6 This is the result of the impact of the impact amplitude on the additional limiting loss of the optical fiber in the embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] On the contrary, the present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention as defined by the claims. Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the detailed description of the present invention below. Those skilled in the art can fully understand the present invention without the description of these details.

[0035] The photonic crystal optical fiber provided by the present invention mainly solves the technical problems that the mechanical strength of the photonic crystal is low due to the presence of internal air holes, the photonic crystal is easily disturbed by external stress loads, and the limiting loss of the optical fiber is increased.

[0036] The design principle of the photonic crystal fiber based on the negative Poisson's ratio unit cell structure in the present invention is: when the material is subjected to unidirectional compression or tension, the Poisson's ratio (μ) of the overall structure is defined as the lateral strain (ε trans ) and longitudinal strain (ε longi ) is the negative value of the ratio:

[0037]

[0038] Where Δx and Δy are the deformations of the optical fiber in the orthogonal directions caused by external loads.

[0039] The presence of stress waves in the medium will change the refractive index of the material and affect the transmission characteristics of light waves, which is the elastic-optical effect. According to the generalized Hooke's law, the deformation of the optical fiber under load is within the elastic deformation range, and there is a linear relationship between stress and strain, that is:

[0040]

[0041] Where, E and v are Young's modulus and Poisson's ratio of the polarization-maintaining fiber, respectively; ε i (i=x,y,z) and ε j (j=xy,yz,xz) are the normal strain and shear strain in the direction of the fiber slow axis, fiber fast axis and fiber transmission axis respectively; σ i (i=x,y,z) and σ j (j=xy, yz, xz) are the normal stress and shear stress in the x, y, and z directions respectively.

[0042] Based on the isotropy of optical fiber materials, the relationship between the change in the refractive index of optical fiber materials and strain is as follows:

[0043]

[0044] In the formula, Δτ i (i=1,2,...,6) is the change of the dielectric impermeability tensor of the optical fiber material; p 11 and p 12 is the elastic-optic coefficient of the optical fiber material, the main diagonal elastic-optic coefficient p 11 represents the change of refractive index under longitudinal stress, and the non-diagonal element p 12 Indicates the change of refractive index under transverse stress, p = (p 11 -p 12 ) / 2. And we have:

[0045]

[0046] In the formula, Δn eff represents the difference in effective refractive index, n 3 eff Represents the effective refractive index raised to the cube.

[0047] The changes in the effective mode refractive index in the three directions of the optical fiber slow axis, optical fiber fast axis, and optical fiber transmission axis caused by the stress load are:

[0048]

[0049] n effx， n effy， n effz Represents the difference in effective refractive index in the x, y, and z directions respectively.

[0050] The refractive index of the optical fiber is the fundamental factor affecting the parameters of the optical fiber transmission mode. From the above formula, it can be seen that in order to ensure the relative stability of the material's refractive index, the stress interference in the optical fiber needs to be strictly controlled. For the optical fiber cross section, the strain caused by external stress will change the refractive index of the material. For porous structures, the Poisson's ratio of the overall structure should be considered. Combining the above formula, we can get:

[0051]

[0052] Δn x is the refractive index difference in the x direction, Δn y is the refractive index difference in the y direction, n 0 is the refractive index of the material when it is unstressed.

[0053] From the above formula, we can know that by controlling the Poisson's ratio of the overall optical fiber structure |μ|<|μ 0 |(μ 0 The change of refractive index caused by external stress can be reduced by reducing the Poisson's ratio of the original structure of the photonic crystal fiber composed of ordinary circular air holes. In addition, when the air hole structure is deformed, the binding ability of the photonic crystal fiber to the polarization state will be weakened. The use of a negative Poisson's ratio unit cell air hole structure can effectively limit the deformation perpendicular to the load direction, thereby reducing the fiber loss. At the same time, structural deformation also affects the electromagnetic mode through the mobile interface effect. By using a negative Poisson's ratio unit cell structure to reduce the Poisson's ratio of the fiber cross section, the fiber can better maintain its original shape, thereby controlling the additional restriction loss caused by external stress loads; the above is the design idea of ​​the stress-interference-resistant photonic crystal fiber with a negative Poisson's ratio unit cell structure.

[0054] The present invention provides an embodiment of a photonic crystal fiber based on a negative Poisson's ratio unit cell structure, wherein the photonic crystal fiber comprises a cladding and a core; a unit cell structure having a negative Poisson's ratio effect is arranged in the cladding;

[0055] The unit cell structure includes a plurality of pore layers (specifically, the plurality of pore layers are arranged in sequence from near to far around the fiber core); each pore layer includes a plurality of elliptical pores arranged around the fiber core, and two adjacent elliptical pores in each pore layer are orthogonally arranged; and two adjacent elliptical pores in two adjacent pore layers are orthogonally arranged.

[0056] Specifically, in the present invention, the orthogonal arrangement means that, on any cross section, the major axes of two adjacent elliptical pores are perpendicular to each other.

[0057] In this embodiment, all elliptical pores in the unit cell structure have the same size parameters; the cross section of the elliptical pore is an ellipse, the major axis radius of the ellipse is 1.5 μm to 2.5 μm, and the minor axis radius is 0.5 μm to 1.4 μm. Preferably, the major axis radius of the ellipse is 2 μm, and the minor axis radius is 1 μm.

[0058] In this embodiment, the distance between two adjacent elliptical pores in adjacent pore layers is equal to the distance between two adjacent elliptical pores in each pore layer. In this embodiment, the distance is 4.5 μm to 7 μm; preferably, the distance is 5.5 μm.

[0059] In this embodiment, the unit cell structure includes 4 to 8 pore layers. Preferably, the unit cell structure includes 4 pore layers.

[0060] In this embodiment, the Poisson's ratio of the overall structure of the photonic crystal fiber ranges from 0.1071 to 0.1904.

[0061] In this embodiment, the photonic crystal fiber is a total internal reflection photonic crystal fiber.

[0062] In the present invention, when the major axis radius of the ellipse of the elliptical air hole is controlled to be 1.5μm to 2.5μm, the minor axis radius is 0.5μm to 1.4μm, and the spacing is 4.5μm to 7μm, the loss of the photonic crystal fiber under a cross-sectional compression of 4.6μm can be reduced from 5.45E-3 to 2.33E-3 compared to the photonic crystal fiber with a circular air hole; the loss when subjected to a 2g impact load is reduced from 8.93E-2 to 5.08E-2.

[0063] The photonic crystal fiber provided by the present invention applies the negative Poisson's ratio structure of the porous structure to the photonic crystal fiber to reduce the loss caused by the fiber deformation when subjected to external stress load, opening up a new idea for the loss suppression of the photonic crystal fiber.

[0064] The photonic crystal fiber provided by the present invention uses a unit cell structure with a negative Poisson's ratio effect and adopts a simple air hole design to reduce the Poisson's ratio of the overall structure, has excellent deformation resistance, and can effectively reduce the additional limiting loss caused by stress loads.

[0065] The present invention reduces the Poisson's ratio of the overall structure of the optical fiber by specifying the shape, size, arrangement and other structural parameters of the air holes of the photonic crystal optical fiber through the tensile expansion effect of the negative Poisson's ratio unit cell, thereby enhancing the energy and shock absorption capabilities of the photonic crystal optical fiber under stress interference. At the same time, the unit cell arrangement structure can also be used as the cladding structure of the photonic crystal optical fiber, and has good versatility.

[0066] Figure 1The orthogonal elliptical hole structure shown in is a typical negative Poisson's ratio unit cell structure. The Poisson's ratio of the overall structure of the photonic crystal fiber composed of the unit cell structure with the negative Poisson's ratio effect ranges from 0.1071 to 0.1904. In the optical fiber, the Poisson's ratio of the structure does not need to be negative. It is only necessary to reduce the Poisson's ratio of the overall structure to achieve the effect of suppressing deformation. In order to apply it to total internal reflection photonic crystal fiber, the elliptical air holes at the core are removed to form an overall optical fiber cross section. Preferably, the elliptical holes in the cross section all have the same size parameters, the major axis radius is 2μm, the minor axis radius is 1μm, the spacing between the centers of adjacent elliptical air holes is 5.5μm, and there are 4 layers of air holes in the cladding.

[0067] The effect of steady-state stress load on the fiber cross section is to cause strain, so it can be analyzed as a compression load; for transient loads, impact is the main factor, so these two methods are used to apply loads to the fiber cross section during the simulation. Figure 2 As shown, the bottom plate applies fixed constraints, and the top plate is used to apply steady-state compression and transient impact loads. The two structures of full circular pores (C) and full longitudinal elliptical pores (L) are compared to verify the anti-stress interference effect of the negative Poisson's ratio unit cell structure under compression and impact loads. The mechanical analysis model used in the simulation verification process adopts the plane stress assumption and takes the unit thickness section as the analysis object. The refractive index of the optical fiber quartz substrate is set to 1.45, the Young's modulus is 78GPa, the Poisson's ratio of the material is 0.186, and the density is 2220kg / m 3 .

[0068] Verification of the ability of optical fiber to resist stress interference under steady-state compressive load: Since the constituent material of photonic crystal fiber is single, the stress load of the cross section can be reflected by the displacement of the cross-sectional boundary. First, the deformation of the optical fiber cross section under different compression amounts is simulated and calculated. When the compression amount is 0, the corresponding optical fiber is not subjected to strain. This is also a reference value for analyzing the additional limiting loss of the optical fiber under other conditions. The value of the compression load is linearly distributed with the size of the optical fiber structure. The maximum value of the analysis range should not cause the pore structure in the cross section to close due to excessive deformation, because the closure of large areas of pores will cause the optical fiber to lose the ability to transmit light waves. The calculation results of Poisson's ratio are as follows: Figure 3 When the external stress load is the same, due to the existence of the negative Poisson's ratio unit cell structure, the outward expansion deformation of the optical fiber cross section is significantly reduced, which is reflected in a lower Poisson's ratio value, which is beneficial to the protection of the internal structure of the optical fiber.

[0069] In order to more realistically reflect the actual situation, wave optics analysis is performed on the cross-sectional deformation structure caused by external stress loads. The limiting loss of the polarization mode without stress is used as a benchmark to analyze the control effect of the negative Poisson's ratio unit cell structure on the additional limiting loss caused by the longitudinal stress load. The method is also applicable to the control of the additional limiting loss of the optical fiber under the transverse stress load. Polarization mode analysis. The same method is used in the following analysis, and the calculation results are as follows Figure 4 shown.

[0070] From the comparison of the additional limiting loss results of the optical fiber under different compression amounts, it can be seen that, thanks to the negative Poisson's ratio unit cell structure's suppression of optical fiber deformation, the photonic crystal fiber with a negative Poisson's ratio unit cell can better limit the influence of compressive stress load on optical fiber loss, which is consistent with the conclusion of theoretical analysis. The additional limiting loss of the photonic crystal fiber with a negative Poisson's ratio unit cell structure is significantly lower than that of the other two structures. The additional limiting loss of the longitudinal elliptical hole structure is almost an order of magnitude higher in the entire test range. This is because the Poisson's ratio of the longitudinal elliptical hole fiber structure is significantly higher than that of the other two structures, which makes the deformation more obvious under the same load. In addition, even though the additional limiting loss of the photonic crystal fiber with a negative Poisson's ratio unit cell structure increases under larger compressive loads, it still maintains the inhibitory effect on limiting loss compared with the other two structures.

[0071] Verification of the ability of optical fiber to resist stress interference under transient impact load: Impact response is also a key mechanical performance test item. Rectangular, half-sine, post-peak sawtooth and other waveforms are usually used to simulate different application environments. Next, a typical half-sine pulse is used to study the response of the optical fiber cross section to the impact load. The waveform function is:

[0072]

[0073] In the formula, F 0 is the impulse waveform amplitude; τ is the pulse duration, which is set to 1ms. The effect of the impulse amplitude of the transient impulse waveform on the Poisson's ratio and additional limiting loss of the optical fiber structure is studied. The results of the Poisson's ratio and additional limiting loss of the optical fiber structure are shown in Figure 5 and Figure 6 shown.

[0074] Similar to the compression load, the strain of the fiber cross section under the impact load reflects the inhibitory effect of the negative Poisson's ratio unit cell structure on the macroscopic deformation of the fiber. Compared with the other two structures, the strain of the fiber with the negative Poisson's ratio unit cell structure under the impact load is still more uniform, and the lateral deformation under the same impact load is significantly reduced. Figure 5 ,6It can be seen that the structural Poisson's ratio and additional confinement loss of the three optical fibers increase as the impact amplitude and time increase, and in the entire test range, the photonic crystal fiber with a negative Poisson's ratio unit cell structure maintains the ability to suppress cross-sectional deformation and additional confinement loss.

[0075] From the simulation results of the effects of both steady-state and transient stress loads on fiber strain, structural Poisson's ratio and additional confinement loss, it can be seen that the negative Poisson's ratio unit cell structure photonic crystal fiber can effectively suppress the fiber cross-sectional deformation caused by stress loads and the additional confinement loss when the fiber is subjected to external stress loads, and is very suitable for complex stress environments.

[0076] The most notable feature of photonic crystal fiber is the flexibility of design, which can meet different performance parameter requirements through structural design. The proposed photonic crystal fiber with a negative Poisson's ratio unit cell structure is also a design method that can utilize structural diversity to improve fiber performance. The practical application of the negative Poisson's ratio unit cell is not limited to the structure analyzed in the previous section, but can be used as a generalized cladding structure. That is, the outer cladding retains the negative Poisson's ratio unit cell structure to resist external stress loads, and the core area structure can be flexibly designed, making it more widely used. The photonic crystal fiber performance evaluation method of the present invention applies loads in the form of steady-state and transient flat plate compression. In the process of fiber parameter evaluation, the influence of pore deformation caused by steady-state and transient stress loads is considered, which is more in line with the actual situation; the optical parameter changes caused by pore deformation under stress load can be accurately analyzed, and the analysis accuracy is improved compared to the traditional refractive index equivalent method.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A photonic crystal fiber based on a negative Poisson's ratio unit cell structure, the photonic crystal fiber comprising a cladding and a core; characterized in that: A unit cell structure having a negative Poisson's ratio effect is arranged in the cladding; The unit cell structure comprises a plurality of pore layers; each pore layer comprises a plurality of elliptical pores arranged around the fiber core, two adjacent elliptical pores in each pore layer are arranged orthogonally; and two adjacent elliptical pores in two adjacent pore layers are arranged orthogonally.

2. A photonic crystal fiber based on a negative Poisson's ratio unit cell structure according to claim 1, characterized in that: All the elliptical pores in the unit cell structure have the same size parameters; the cross section of the elliptical pore is an ellipse, the major axis radius of the ellipse is 1.5 μm to 2.5 μm, and the minor axis radius is 0.5 μm to 1.4 μm.

3. The photonic crystal fiber based on a negative Poisson's ratio unit cell structure according to claim 1, characterized in that: The distance between two adjacent elliptical pores in adjacent pore layers is equal to the distance between two adjacent elliptical pores in each pore layer.

4. A photonic crystal fiber based on a negative Poisson's ratio unit cell structure according to claim 3, characterized in that: The spacing is 4.5 μm to 7 μm.

5. The photonic crystal fiber based on a negative Poisson's ratio unit cell structure according to claim 1, characterized in that: The unit cell structure includes 4 to 8 pore layers.

6. The photonic crystal fiber based on a negative Poisson's ratio unit cell structure according to claim 1, characterized in that: The Poisson's ratio value range of the overall structure of the photonic crystal optical fiber is: 0.1071-0.1904.

7. The photonic crystal fiber based on a negative Poisson's ratio unit cell structure according to claim 1, characterized in that: The photonic crystal fiber is a total internal reflection type photonic crystal fiber.

Images