A low-loss, bend-resistant hollow-core antiresonant fiber for 980nm pump light

Abstract

The present invention discloses a low-loss, bend-resistant hollow-core antiresonant optical fiber for 980nm pump light, which relates to the field of optical fiber laser technology. The optical fiber comprises, from the outside to the inside, an outer cladding, an inner cladding, and a core. The inner cladding is an antiresonant region, and the inner cladding includes four antiresonant units, each of which includes a nested circular dielectric tube and a non-nested fan-shaped dielectric tube. The circular dielectric tube includes a first type of circular dielectric tube, wherein a second type of circular dielectric tube and three third type of circular dielectric tubes are nested inside the first type of circular dielectric tube. The present invention combines a multi-layer nested circular dielectric tube structure with a non-nested fan-shaped dielectric tube structure to significantly reduce the transmission loss of the optical signal, making the propagation of the optical signal more stable, reducing energy scattering and leakage, and ensuring efficient light energy transmission. In addition, the structure provides more flexibility in the processing and manufacturing process, facilitating mass production.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber lasers, and in particular to a low-loss, bend-resistant hollow-core anti-resonant optical fiber applied to 980nm pump light. Background Art

[0002] Lasers with a wavelength of 980nm are widely used in fiber lasers, fiber amplifiers, and other optoelectronic devices. In particular, they are used as pumping light sources for important fiber systems such as ytterbium-doped fiber lasers and erbium-doped fiber amplifiers, promoting technological progress in many fields such as optical communications, laser processing, and medical diagnosis.

[0003] Because the beam quality of multimode fiber lasers cannot meet the requirements of high-precision applications, further performance improvements have been limited. Therefore, research on 980nm single-mode lasers has gradually become a hot topic in recent years. To broaden the application areas of 980nm lasers, the key to promoting the development of this technology is to adopt innovative technologies to achieve single-mode output and increase the power of single-mode lasers. Hollow-core antiresonant fiber, by providing a larger core size while maintaining single-mode characteristics, has opened up a new path to achieving high-power 980nm single-mode fiber lasers.

[0004] As an innovative fiber structure, hollow-core antiresonant fiber, with its unique design and excellent performance, is playing an increasingly important role in fiber lasers, fiber-optic communications, and other high-power laser applications. However, existing hollow-core antiresonant fibers suffer from high production costs, relatively complex structures, and challenges in efficient fabrication. Furthermore, optical signal transmission losses need to be reduced. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm pump light to solve the problems raised in the above background technology.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm pump light, comprising, from the outside to the inside, an outer cladding, an inner cladding, and a core;

[0007] The inner cladding is an anti-resonance region, and the inner cladding includes four anti-resonance units, each of which includes a circular dielectric tube with a nested structure and a fan-shaped dielectric tube with a non-nested structure;

[0008] The circular medium tube includes a first type of circular medium tube, wherein a second type of circular medium tube and three third type of circular medium tubes are nested inside the first type of circular medium tube;

[0009] The outer cladding is a cylindrical structure, and the outer cladding and the inner cladding are distributed in concentric circles;

[0010] The fiber core is filled with air and is composed of a plurality of anti-resonance units in the inner cladding.

[0011] Preferably, the wall thickness t of the third type circular dielectric tube, the second type circular dielectric tube, and the first type circular dielectric tube is the same, satisfying the anti-resonance condition:

[0012]

[0013] Where λ represents the designed operating wavelength, n1 and n0 are the refractive index of the dielectric tube material and the refractive index of air, respectively, and m is an integer.

[0014] Preferably, the interiors of the three types of circular medium tubes, the second type of circular medium tubes, and the first type of circular medium tubes are all filled with air, and the base materials of the three types of circular medium tubes, the second type of circular medium tubes, and the first type of circular medium tubes are all made of silicon dioxide.

[0015] Preferably, the base material of the outer cladding is silicon dioxide, and the radius of the outer cladding is 125 μm;

[0016] A perfect matching layer is provided on the outer side of the outer cladding, wherein the material of the perfect matching layer is silicon dioxide and the thickness is 5 μm;

[0017] The fiber core is filled with air, and the radius of the fiber core is 20 μm.

[0018] Preferably, there is no node between the circular medium tube and the fan-shaped medium tube;

[0019] The circular medium tubes in the nested structure are distributed at equal intervals between the fan-shaped medium tubes.

[0020] Preferably, the fan-shaped medium tubes are 90° apart from each other, and the circular medium tubes in each two sets of nested structures are symmetrically located on both sides of the fan-shaped medium tube, with an included angle of 45°.

[0021] Preferably, the radius of the sector-shaped dielectric tube is 32 μm, the central angle is 60°, the radius of the chamfer is 1 μm, the glass tube wall of the sector-shaped dielectric tube is silicon dioxide, and the interior thereof is air.

[0022] Preferably, the radius of the first type of circular medium tube is 42.2 μm;

[0023] The second type of circular medium tube and the first type of circular medium tube are in a concentric circle structure, and the radius of the second type of circular medium tube is 20 μm;

[0024] The three third-type circular medium tubes are tangent to the second-type circular medium tube. The angles between the third-type circular medium tube at the center and the third-type circular medium tubes on both sides thereof are both 90°. The radius of the third-type circular medium tube is 12.2 μm.

[0025] The invention discloses an application of a hollow-core antiresonant optical fiber in a 980nm single-mode laser source.

[0026] Preferably, the operating wavelength band of the hollow-core anti-resonant optical fiber body is 0.6-1.2 μm, meeting the transmission requirements of 980 nm pump light.

[0027] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0028] 1. The hollow-core antiresonant optical fiber of the present invention utilizes a multi-layer nested circular dielectric tube structure combined with a non-nested fan-shaped dielectric tube structure. This unique design not only effectively confines the light field to the core region of the optical fiber, thereby significantly reducing the transmission loss of the optical signal, but also, due to its simplified structure, makes the manufacturing process more efficient and easy to implement. This design optimizes the antiresonant characteristics of the optical fiber, making the propagation of the optical signal more stable, reducing energy scattering and leakage, and ensuring efficient light energy transmission. In addition, this structure provides greater flexibility in the processing and manufacturing process, facilitates mass production, and reduces production costs.

[0029] Therefore, the present invention not only improves the optical performance of the optical fiber, but also enhances its operability and economy in practical applications;

[0030] 2. The antiresonant hollow-core fiber of the present invention can operate over a wide wavelength range of 0.6-1.2 μm and can be used to transmit high-power single-mode laser sources in the 980 nm band. The loss at 980 nm is approximately 1.1144 × 10-9 dB / km, with a dispersion flatness close to zero and a nonlinear coefficient of approximately 0.26053 (W·km)-1. Within a bending radius of 5-15 cm, the loss ranges from 1.0976 × 10-9 to 8.4119 × 10-6 dB / km. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0032] FIG1( a ) and FIG1( b ) are schematic cross-sectional views of a hollow-core antiresonant optical fiber according to the present invention;

[0033] Figure 2 A diagram showing the fundamental mode of a cross section of a hollow-core antiresonant optical fiber and a three-dimensional height representation of the present invention;

[0034] Figure 3The electric field mode contour distribution diagram of the base film of the hollow-core antiresonant optical fiber of the present invention at 0.98 μm;

[0035] Figure 4 is a graph showing the relationship between the limiting loss of the fundamental mode of the present invention and the change in wavelength;

[0036] Figure 5 This is a graph showing the relationship between the fundamental mode nonlinear coefficient and wavelength of the present invention;

[0037] Figure 6 This is a graph showing the relationship between the fundamental mode dispersion coefficient and wavelength of the present invention;

[0038] Figure 7 A graph showing the relationship between bending loss and bending radius when bending in the X direction at a wavelength of 0.98 μm provided by the present invention;

[0039] Figure 8 This is a relationship diagram of the bending loss when bending in the Y direction at a wavelength of 0.98μm as compared with the bending radius provided by the present invention.

[0040] Description of reference numerals:

[0041] 1. Outer cladding; 2. Third-type circular dielectric tube; 3. Second-type circular dielectric tube; 4. First-type circular dielectric tube; 5. Fiber core; 6. Fan-shaped dielectric tube; 7. Perfectly matched layer; 8. Inner cladding. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0043] Embodiment 1:

[0044] As shown in FIG1( a ), a low-loss bend-resistant hollow-core antiresonant optical fiber for 980 nm pump light comprises, from outside to inside, an outer cladding 1, an inner cladding 8, and a core 5;

[0045] The inner cladding 8 is an anti-resonance region, and the inner cladding 8 includes four anti-resonance units, each of which includes a circular dielectric tube with a nested structure and a fan-shaped dielectric tube with a non-nested structure 6;

[0046] The circular medium tubes include a first type circular medium tube 4, wherein a second type circular medium tube 3 and three third type circular medium tubes 2 are nested inside the first type circular medium tube 4;

[0047] The outer cladding 1 is a cylindrical structure, and the outer cladding 1 and the inner cladding 8 are distributed in concentric circles;

[0048] The interiors of the third type of circular medium tube 2, the second type of circular medium tube 3, and the first type of circular medium tube 4 are all air, and the base materials of the third type of circular medium tube 2, the second type of circular medium tube 3, and the first type of circular medium tube 4 are all silicon dioxide;

[0049] The base material of the outer cladding 1 is silicon dioxide, and the radius of the outer cladding 1 is 125 μm;

[0050] A perfect matching layer 7 is provided on the outside of the outer cladding layer 1. The material of the perfect matching layer 7 is silicon dioxide and the thickness is 5 μm.

[0051] The core 5 is filled with air, and the radius of the core 5 is 20 μm.

[0052] There is no node between the circular medium tube and the fan-shaped medium tube 6;

[0053] The circular medium pipes of the nested structure are distributed at equal intervals between the fan-shaped medium pipes 6 .

[0054] Each sector-shaped medium tube 6 is at 90 degrees to each other, and each two groups of circular medium tubes in the nested structure are symmetrically located on both sides of the sector-shaped medium tube 6, with an included angle of 45 degrees.

[0055] The radius of the sector-shaped dielectric tube 6 is 32 μm, the central angle is 60°, the radius of the chamfer is 1 μm, the glass tube wall of the sector-shaped dielectric tube 6 is silicon dioxide, and the interior thereof is air.

[0056] The radius of the first type of circular dielectric tube 4 is 42.2 μm;

[0057] The second type of circular medium tube 3 and the first type of circular medium tube 4 are in a concentric circle structure, and the radius of the second type of circular medium tube 3 is 20 μm;

[0058] The three third-type circular medium tubes 2 are tangent to the second-type circular medium tube 3 . The angles between the third-type circular medium tube 2 at the center and the third-type circular medium tubes 2 on both sides are 90°. The radius of the third-type circular medium tube 2 is 12.2 μm.

[0059] As shown in FIG1( b ), the wall thickness t of the third type circular dielectric tube 2 , the second type circular dielectric tube 3 , and the first type circular dielectric tube 4 are the same, satisfying the antiresonance condition:

[0060]

[0061] Where λ represents the designed operating wavelength, n1 and n0 are the refractive index of the dielectric tube material and the refractive index of air, respectively, and m is an integer;

[0062] In this embodiment, t is 2.2 μm;

[0063] In this embodiment:

[0064] The diameter d4 of the inner cladding 8 is 208.8 μm; the radius r2 of the scallop-shaped dielectric tube 6 is 32 μm, the central angle θ1 is 60°, the radius of the chamfer r1 is 1 μm, and the angle θ2 with the first type circular dielectric tube 4 is 45°;

[0065] The diameter d1 of the first type of circular dielectric tube 4 is 84.4 μm and is tangent to the outer wall of the inner cladding 8;

[0066] The diameter d3 of the second type circular medium tube 3 is 40 μm, and it forms a concentric circle structure with the first type circular medium tube 4;

[0067] The diameter d2 of the third type of circular medium tube 2 is 24.4 μm, and it is tangential to the second type of circular medium tube 3 and vertically distributed around the second type of circular medium tube 3;

[0068] The interiors of the scallop-shaped dielectric tube 6, the first type circular dielectric tube 4, the second type circular dielectric tube 3 and the third type circular dielectric tube 2 are all air with a refractive index of 1. The base material of the dielectric tube wall is silicon dioxide with a refractive index of 1.4481 to 1.458;

[0069] The outer cladding 1 has a diameter d5 of 250 μm, and the base material is silicon dioxide with a refractive index of 1.4481 to 1.458;

[0070] The fiber core 5 is filled with air, has a refractive index of 1, and a radius of approximately 20 μm. It is composed of multiple antiresonant units in the inner cladding 8 and is the main light-guiding area of ​​the hollow-core antiresonant optical fiber.

[0071] In this embodiment, a perfect matching layer 7 is provided outside the outer cladding 1; the base material of the perfect matching layer 7 is silicon dioxide with a thickness of 5 μm, wherein the perfect matching layer 7 is used to eliminate the environmental difference between the optical fiber model and the actual optical fiber.

[0072] Example 2:

[0073] This embodiment uses simulation tests to demonstrate the superiority of the hollow-core antiresonant optical fiber in Example 1.

[0074] Finite element simulation software COMSOL Multiphysics was used for simulation, and theoretical calculations were performed using the finite element method and the perfectly matched layer boundary absorption condition. The calculations yielded a relationship diagram showing the mode field distribution, confined loss, dispersion, nonlinear coefficient, and bending loss of the hollow-core antiresonant fiber in Example 1.

[0075] Figure 2 The figure shows the two-dimensional mode field distribution and three-dimensional height expression of the hollow core antiresonant fiber at the 980nm fundamental mode. Figure 2It can be seen that when the hollow-core antiresonant fiber transmits optical signals, it can concentrate the energy in the core area, indicating that the light is well confined in the core area and the transmitted light has excellent beam quality.

[0076] Figure 3 The figure shows the electric field mode contour line distribution of the fundamental mode at 980nm. It can be seen from the figure that the electric field mode contour lines of the hollow-core optical fiber with an antiresonant structure prepared in the embodiment are all concentrated in the core area during light wave transmission, indicating that the light is well confined in the core area.

[0077] Figure 4 The figure shows the relationship between the limiting loss of the hollow core anti-resonant fiber base film and the wavelength (0.6-1.2μm). Figure 4 It can be seen that the limit loss of hollow core antiresonant fiber is at a low level under the condition of incident wavelength of 0.6-1.2μm, and the minimum loss is 1.0239*10 at 7.5μm. -10 dB / km, the loss at 0.98μm is 1.1144*10 - 9 dB / km, which is much lower than the 0.2dB / km of traditional single-mode fiber. This shows that it plays an important role in single-mode laser sources in the 980nm band.

[0078] Figure 5 The graph shows the relationship between the nonlinear coefficient of the hollow core anti-resonant fiber base film and the wavelength. Figure 5 It can be seen that the nonlinear coefficient of hollow-core antiresonant fiber is low in the 0.6-1.2μm band, and the value is stable at 0.21~0.42 (W·km) -1 This shows that by reducing signal distortion and energy loss, this optical fiber can improve transmission efficiency, support higher power, and maintain signal stability, thus playing an important role in applications such as high-power laser transmission, optical fiber communication, and optical fiber sensing.

[0079] Figure 6 The figure shows the relationship between the dispersion of the hollow core anti-resonant fiber base film and the wavelength. Figure 6 The hollow-core antiresonant fiber, as seen in the figure, exhibits dispersion variations in the 0.6-1.2 μm wavelength range, with group velocity dispersion approaching zero. Near-zero dispersion fiber effectively suppresses pulse broadening and dispersion effects, ensuring signal stability and high-precision transmission in ultrafast laser systems and long-distance communications.

[0080] Figure 7 and Figure 8 The graph below shows the relationship between the bending loss of hollow core antiresonant fiber and the bending radius in the 980nm band. Figure 7 and Figure 8It can be seen that the hollow core antiresonant fiber has low bending loss when bending in the x and y directions under the condition of a transmission wavelength of 980nm. When the bending radius is 5cm, the bending loss of the fiber when bending in the x and y directions is 1.5121*10 -6 dB / km and 8.4119*10 -6 dB / km; when the bending radius is 7cm, the bending loss is 8.1122*10 -7 dB / km and 1.0291*10 -7 dB / km; thereafter, as the bending radius increases, the bending loss of the optical fiber when bent in the x and y directions is 10 -7 ~10 -10 The dB / km level indicates that the hollow-core antiresonant fiber in Example 1 has excellent bending resistance and can maintain stable optical signal transmission in complex wiring or confined spaces. It is widely used in environments that require frequent bending, such as optical fiber communications, medical equipment, and optical fiber sensing systems.

[0081] In summary, the hollow-core antiresonant fiber described in the present invention has a spectral bandwidth of 0.6μm (0.6-1.2μm), can be used for optical signal transmission of a 980nm single-mode laser source, and has the characteristics of low dispersion, low nonlinearity and low loss, and also has anti-bending properties.

[0082] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm pump light, characterized in that: From outside to inside, it includes: an outer cladding (1), an inner cladding (8) and a fiber core (5); The inner cladding (8) is an anti-resonance region, and the inner cladding (8) includes four anti-resonance units, and the anti-resonance units include circular dielectric tubes with a nested structure and fan-shaped dielectric tubes with a non-nested structure (6); The circular medium tube comprises a first type of circular medium tube (4), wherein a second type of circular medium tube (3) and three third type of circular medium tubes (2) are nested inside the first type of circular medium tube (4); The outer cladding (1) is a cylindrical structure, and the outer cladding (1) and the inner cladding (8) are distributed in concentric circles; The fiber core (5) is filled with air, and the fiber core (5) is composed of a plurality of anti-resonance units in the inner cladding (8); The interiors of the three types of circular medium tubes (2), the second type of circular medium tubes (3), and the first type of circular medium tubes (4) are all filled with air; There are no nodes between the circular medium tube and the fan-shaped medium tube (6); The circular medium tubes of the nested structure are distributed at equal intervals between the fan-shaped medium tubes (6); Each of the fan-shaped medium tubes (6) is 90 degrees to each other, and each two groups of the circular medium tubes in the nested structure are symmetrically located on both sides of the fan-shaped medium tube (6), with an included angle of 45 degrees; The second type of circular medium tube (3) and the first type of circular medium tube (4) are in a concentric circle structure, and the radius of the second type of circular medium tube (3) is 20 μm; The three third-type circular medium tubes (2) are tangent to the second-type circular medium tube (3), and the angles between the third-type circular medium tube (2) located in the center and the third-type circular medium tubes (2) on both sides thereof are all 90°; The diameter d2 of the third type circular medium tube 2 is 24.4 μm, is tangent to the second type circular medium tube 3 , and is vertically distributed around the second type circular medium tube 3 .

2. The low-loss bend-resistant hollow-core antiresonant optical fiber for 980 nm pump light according to claim 1, characterized in that: The wall thickness t of the third type circular dielectric tube (2), the second type circular dielectric tube (3) and the first type circular dielectric tube (4) is the same, satisfying the anti-resonance condition: Where λ represents the designed operating wavelength, n1 and n0 are the refractive index of the dielectric tube material and the refractive index of air, respectively, and m is an integer.

3. The low-loss bend-resistant hollow-core antiresonant optical fiber for 980 nm pump light according to claim 2, characterized in that: The base materials of the three types of circular medium tubes (2), the second type of circular medium tubes (3), and the first type of circular medium tubes (4) are all silicon dioxide.

4. The low-loss bend-resistant hollow-core antiresonant optical fiber for 980 nm pump light according to claim 3, characterized in that: The base material of the outer cladding (1) is silicon dioxide, and the radius of the outer cladding (1) is 125 μm; A perfect matching layer (7) is provided on the outside of the outer cladding layer (1), and the material of the perfect matching layer (7) is silicon dioxide and has a thickness of 5 μm; The fiber core (5) is filled with air, and the radius of the fiber core (5) is 20 μm.

5. The low-loss bend-resistant hollow-core antiresonant optical fiber for 980 nm pump light according to claim 4, characterized in that: The radius of the sector-shaped medium tube (6) is 32 μm, the central angle is 60°, and the radius of the chamfer is 1 μm. The glass tube wall of the sector-shaped medium tube (6) is silicon dioxide, and the interior thereof is air.

6. The low-loss bend-resistant hollow-core antiresonant optical fiber for 980 nm pump light according to claim 5, characterized in that: The radius of the first type of circular medium tube (4) is 42.2 μm; The radius of the third type circular medium tube (2) is 12.2 μm.

7. Use of the hollow-core antiresonant optical fiber according to claim 6 in a 980 nm single-mode laser source.

8. The use according to claim 7, comprising a hollow-core antiresonant optical fiber body, characterized in that: The operating wavelength band of the hollow-core anti-resonance optical fiber body is 0.6-1.2 μm.

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