Silicon-coated nested single-polarization single-mode hollow core optical fiber

Abstract

The application discloses a silicon-coated nested single-polarization single-mode hollow optical fiber, which comprises an outer structure tube and a plurality of double-layer anti-resonance cladding tubes, wherein each double-layer anti-resonance cladding tube is arranged at equal intervals along the inner wall of the outer structure tube, and each double-layer anti-resonance cladding tube comprises an inner layer cladding and an outer layer cladding which are mutually circumscribed; the inner layer cladding is a coaxially nested anti-resonance tube, which comprises a peripheral cladding tube with a large aperture and an internal cladding tube with a small aperture which is coaxially nested in the hole of the peripheral cladding tube, the peripheral cladding tube and the internal cladding tube are mutually inscribed, and the inscribed point and the circumscribed point are coincident; and the outer layer cladding is an anti-resonance tube and is mutually inscribed with the outer structure tube. The double-layer anti-resonance cladding tube can realize high-quality single-mode single-polarization transmission with a continuous bandwidth of 60 nm near the central wavelength, the average transmission loss is low, and the near-zero flat dispersion characteristic is possessed.

Description

Technical Field

[0001] This invention relates to the field of optical fiber communication, and more particularly to a silicon-coated nested single-polarization single-mode hollow optical fiber. Background Technology

[0002] Single-polarization single-mode hollow-core fiber is formed by combining single-polarization single-mode fiber and hollow-core fiber, possessing the advantages of both. Hollow-core fiber overcomes the material limitations of solid-core fiber, achieving a synergy of low loss, low nonlinearity, and a wide transmission window. The characteristic of the light field propagating in the air core significantly reduces Rayleigh scattering loss and greatly weakens nonlinear effects, providing greater flexibility for expanding channel capacity in dense wavelength division multiplexing (DWDM) systems. In fiber optic communication systems, single-polarization single-mode fiber, through special structural design, allows only one polarization state of the fundamental mode to be transmitted with low loss, while the other orthogonal polarization state and all higher-order modes are effectively cut off, fundamentally eliminating polarization mode dispersion, polarization correlation loss, and polarization crosstalk. This characteristic solves the inter-symbol interference problem caused by optical pulse broadening in ultra-high-speed transmission, preventing an increase in the system's bit error rate.

[0003] Existing mainstream single-polarization single-mode hollow fiber suffers from high limiting loss, necessitating a new fiber structure to reduce fiber loss. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems existing in the related art.

[0005] The purpose of this invention is to provide a silicon-coated nested single-polarization single-mode hollow fiber to solve the problem of high energy consumption in existing optical fibers.

[0006] To achieve the above objectives, the present invention provides a silicon-coated nested single-polarization single-mode hollow-core optical fiber, comprising:

[0007] Outer structural tube;

[0008] Multiple double-layer anti-resonant cladding tubes are arranged at equal intervals along the inner wall of the outer structural tube. Each double-layer anti-resonant cladding tube includes an inner cladding and an outer cladding that are mutually tangent. The inner cladding is a coaxially nested anti-resonant tube, comprising an outer cladding tube with a larger aperture and an inner cladding tube with a smaller aperture, coaxially nested within the outer cladding tube. The outer cladding tube and the inner cladding tube are internally tangent, and the internal tangency point coincides with the external tangency point. The outer cladding is an anti-resonant tube and is internally tangent to the outer structural tube.

[0009] The outer structure tube, outer cladding tube, inner cladding tube, and anti-resonant tube are circular structures made of silicon dioxide. The outer structure tube, outer cladding tube, inner cladding tube, and anti-resonant tube are filled with a preset filler inside and out. The working wavelength of the optical fiber is 1500nm.

[0010] A further preferred embodiment of the present invention is that the preset filler is air, and the area enclosed by the plurality of inner layers is an air core.

[0011] Preferably, the diameter ratio of each outer cladding tube to the air core is 0.9.

[0012] Preferably, the diameter ratio of each anti-resonant tube to the air fiber core is 0.585.

[0013] Preferably, the diameter ratio of each anti-resonant tube to each outer cladding tube is 0.22.

[0014] Preferably, the diameter of the air fiber core is 22 μm;

[0015] The wall thickness of each anti-resonant tube, inner cladding tube, and outer cladding tube is 0.5 μm.

[0016] Preferably, in each coaxial nested anti-resonant tube, a silicon coating with a thickness of 0.0925 μm is deposited on the inner wall of one outer cladding tube and the inner wall of its corresponding inner cladding tube.

[0017] Preferably, the refractive index of the silicon coating is 3.48.

[0018] Preferably, the number of the double-layer anti-resonant cladding tubes is 6.

[0019] Preferably, the outer structure tube and the double-layer anti-resonance cladding tube are made of silicon dioxide with a refractive index of 1.45.

[0020] Beneficial Effects: This invention employs a dual-layer synergistic structure supplemented by six sets of double-nested anti-resonant tubes and six symmetrical outer auxiliary anti-resonant tubes. The core tube achieves basic optical field constraint through anti-resonance reflection, while the auxiliary tubes further compress the mode field through near-field coupling, forming a strong optical field confinement system and significantly reducing fundamental mode confinement loss. Simultaneously, the double-nested structure naturally cuts off most higher-order modes, and the auxiliary tubes provide secondary suppression of residual higher-order modes, thus enhancing single-mode transmission characteristics through dual-layer filtering. By depositing high-refractive-index silicon coatings on an outer cladding tube and its corresponding inner cladding tube, and utilizing the polarization-differential coupling loss mechanism, orthogonal polarization states generate loss differences. Furthermore, through precise design of coating parameters, the polarization modulation effect is stably maintained across a wide wavelength range, overcoming the bottleneck of narrow single-polarization bandwidth in traditional structures. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a silicon-coated nested single-polarization single-mode hollow fiber according to the present invention.

[0022] Figure 2 This is a flowchart of the forward-inverse global optimization process for machine learning constructed using a multilayer perceptron neural network.

[0023] Among them, 1-outer structure tube; 2-outer cladding tube; 3-inner cladding tube; 4-anti-resonance tube; 5-air fiber core; - Diameter of the outer cladding tube; - Diameter of the inner cladding tube; D - Diameter of the air core; - Diameter of the anti-resonant tube; - The thickness of each cladding tube; -Silicon coating thickness. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] The following is combined Figure 1 This invention describes a silicon-coated nested single-polarization single-mode hollow optical fiber, the optical fiber comprising: an outer structure tube 1 and multiple double-layer anti-resonant cladding tubes.

[0026] Multiple double-layer anti-resonant cladding tubes are arranged at equal intervals along the inner wall of the outer structural tube. Each double-layer anti-resonant cladding tube includes an inner cladding and an outer cladding that are mutually tangent. The inner cladding is a coaxially nested anti-resonant tube, comprising an outer cladding tube 2 with a larger aperture and an inner cladding tube 3 with a smaller aperture, coaxially nested within the outer cladding tube. The outer cladding tube and the inner cladding tube are internally tangent, and the internal tangency point coincides with the external tangency point. The outer cladding is an anti-resonant tube and is internally tangent to the outer structural tube.

[0027] The outer structure tube 1, the outer cladding tube 2, the inner cladding tube 3, and the anti-resonance tube 4 are circular structures made of silicon dioxide. The outer structure tube 1, the outer cladding tube 2, the inner cladding tube 3, and the anti-resonance tube 4 are filled with a preset filler inside and out. The working wavelength of the optical fiber is 1500nm.

[0028] In some embodiments, the preset filler is air, and the area enclosed by the plurality of inner cladding layers is an air core 5.

[0029] In some embodiments, the diameter ratio of each outer cladding tube 2 to the air core 5 is... The ratio is 0.9, which is the diameter ratio of each anti-resonant tube 4 to the air fiber core 5. The ratio of the diameter of each anti-resonant tube 4 to the diameter of each outer cladding tube 2 is 0.585. It is 0.22.

[0030] In some embodiments, the diameter of the air fiber core 5 is 22 μm; the wall thickness of each anti-resonance tube 4, inner cladding tube 3, and outer cladding tube 2 is... All are 0.5μm.

[0031] In some embodiments, in each coaxial nested anti-resonant tube, the deposition thickness of the inner wall of an outer cladding tube and its corresponding inner cladding tube is [not specified]. The silicon coating is 0.0925 μm thick and has a direct emissivity of 3.48.

[0032] In some embodiments, the number of the double-layer anti-resonant cladding tubes is 6.

[0033] In some embodiments, the silicon dioxide used in the outer structure tube 1 and the double-layer anti-resonant cladding tube has a direct emissivity of 1.45.

[0034] The calculation method for the structural parameters of silicon-coated nested single-polarization single-mode hollow fiber provided by this invention is as follows:

[0035] like Figure 2 As shown, firstly, based on the anti-resonance condition, a working wavelength of 1550 nm is matched. Combining existing experience in optimizing parameters of hollow-core anti-resonant fibers with the polarization modulation mechanism of silicon coating, while also considering fabrication tolerance, the thickness of the fiber cladding tube is limited. High refractive index coating thickness , core diameter D, and the ratio of the diameter of the outer cladding tube 2 to the diameter of the air core 5 The diameter ratio of the anti-resonant tube 4 to the air fiber core 5 The diameter ratio of the anti-resonant tube 4 to the outer cladding tube 2 The value range of these six core structural parameters was determined by generating 5000 sets of structural parameters in the parameter space using the full vector finite element method and Latin hypercube sampling. Simulations were performed in COMSOL in the 1450–1650 nm band to obtain four indicators: confinement loss, polarization extinction ratio, higher-order mode extinction ratio, and dispersion coefficient. A dataset was then constructed, and after outlier removal and normalization preprocessing, it was divided into training and testing sets. Subsequently, a multilayer perceptron neural network with four hidden layers was built, using the structural parameters as input and performance indicators as output. A forward prediction model was trained using the Adam optimizer and mean square error as the loss function based on the TensorFlow framework. Then, a reverse design model was constructed through two stages of training, using target performance such as single-polarization single-mode transmission as input and structural parameters as output. During this process, the weights of polarization extinction ratio and higher-order mode extinction ratio were increased. Finally, the structural parameters obtained from the reverse model optimization were imported into COMSOL for secondary simulation verification. After confirming that they met the performance requirements of the working band, the specific parameters of the optical fiber of this invention were finally determined. = 0.500μm, = 0.925μm, D = 22.0μm, = 0.900, = 0.585, = 0.220.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon-coated nested single-polarization single-mode hollow-core optical fiber, characterized in that, include: Outer structural tube; Multiple double-layer anti-resonant cladding tubes are arranged at equal intervals along the inner wall of the outer structural tube. Each double-layer anti-resonant cladding tube includes an inner cladding and an outer cladding that are mutually tangent. The inner cladding is a coaxially nested anti-resonant tube, comprising an outer cladding tube with a larger aperture and an inner cladding tube with a smaller aperture, coaxially nested within the outer cladding tube. The outer cladding tube and the inner cladding tube are internally tangent, and the internal tangency point coincides with the external tangency point. The outer cladding is an anti-resonant tube and is internally tangent to the outer structural tube. The outer structure tube, outer cladding tube, inner cladding tube, and anti-resonant tube are circular structures made of silicon dioxide. The outer structure tube, outer cladding tube, inner cladding tube, and anti-resonant tube are filled with a preset filler inside and out. The working wavelength of the optical fiber is 1500nm.

2. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 1, characterized in that, The preset filler is air, and the area enclosed by the multiple inner cladding layers is an air core.

3. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 2, characterized in that, The diameter ratio of each outer cladding tube to the air core is 0.

9.

4. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 3, characterized in that, The diameter ratio of each anti-resonant tube to the air fiber core is 0.

585.

5. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 4, characterized in that, The diameter ratio of each anti-resonant tube to each outer cladding tube is 0.

22.

6. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 5, characterized in that, The diameter of the air fiber core is 22 μm; The wall thickness of each anti-resonant tube, inner cladding tube, and outer cladding tube is 0.5 μm.

7. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 6, characterized in that, In each coaxial nested anti-resonant tube, a silicon coating with a thickness of 0.0925 μm is deposited on the inner wall of one outer cladding tube and the inner wall of its corresponding inner cladding tube.

8. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 7, characterized in that, The direct emissivity of the silicon coating is 3.

48.

9. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 8, characterized in that, The number of double-layer anti-resonant cladding tubes is 6.

10. The silicon-coated nested single-polarization single-mode hollow-core optical fiber according to claim 9, characterized in that, The silicon dioxide used in the outer structure tube and the double-layer anti-resonance cladding tube has a direct emissivity of 1.45.

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