Low-loss bending-resistant hollow-core anti-resonance optical fiber applied to 980nm pump light

Abstract

The invention discloses a low-loss bending-resistant hollow-core anti-resonance optical fiber applied to 980nm pump light, and relates to the technical field of optical fiber lasers, and the low-loss bending-resistant hollow-core anti-resonance optical fiber sequentially comprises an outer cladding, an inner cladding and a fiber core from outside to inside; the inner cladding is an anti-resonance area, the inner cladding comprises four anti-resonance units, and each anti-resonance unit comprises a circular dielectric tube of a nested structure and a fan-shaped dielectric tube of a non-nested structure; the circular medium pipe comprises a first-class circular medium pipe, and a second-class circular medium pipe and three third-class circular medium pipes are nested in the first-class circular medium pipe. The multi-layer nested circular dielectric tube structure and the non-nested fan-shaped dielectric tube structure are combined, so that the transmission loss of optical signals is remarkably reduced, the transmission of the optical signals is more stable, the scattering and leakage of energy are reduced, and meanwhile, the efficient optical energy transmission is ensured; in addition, the structure provides more flexibility in the machining and manufacturing process, and batch production is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber lasers, and in particular to a low-loss bending-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, especially 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] Since the beam quality of multimode fiber lasers cannot meet the requirements of high-precision applications, which limits the further improvement of their performance, the research on 980nm single-mode lasers has gradually become a hot topic in recent years. In order to broaden the application field of 980nm lasers, the key to promoting the development of this technology is to use innovative technologies to achieve single-mode output and increase the power of single-mode lasers. Hollow-core antiresonant fiber opens up a new path to achieve high-power 980nm single-mode fiber lasers by providing a larger core size while maintaining single-mode characteristics.

[0004] As an innovative fiber structure, hollow core antiresonant fiber plays an increasingly important role in fiber lasers, fiber communications and other high-power laser applications due to its unique design and excellent performance. However, the existing hollow core antiresonant fiber has high production costs, relatively complex structures, and is not easy to manufacture efficiently. The transmission loss of optical signals needs 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 bending-resistant hollow-core antiresonant optical fiber applied to 980nm pump light, which comprises, 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, and the anti-resonance units include circular dielectric tubes with a nested structure and fan-shaped dielectric tubes with a non-nested structure;

[0008] The circular medium tube comprises 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] Wherein, λ represents the designed working 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 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 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 arranged on the outer side of the outer cladding, 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 are no nodes between the circular medium tube and the fan-shaped medium tube;

[0019] The circular medium tubes of the nested structure are evenly spaced and distributed between the fan-shaped medium tubes.

[0020] Preferably, the fan-shaped medium tubes are 90° to each other, and the circular medium tubes in each two groups of nested structures are symmetrically located on both sides of the fan-shaped medium tubes, 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°, and 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 anti-resonant optical fiber of the present invention adopts a combination of a multi-layer nested circular dielectric tube structure and a non-nested fan-shaped dielectric tube structure. This unique design can not only effectively confine the light field to the core area of ​​the optical fiber, thereby significantly reducing the transmission loss of the optical signal, but also because of its simplified structure, the manufacturing process is more efficient and easy to implement. Through this design, the anti-resonant characteristics of the optical fiber are optimized, making the propagation of the optical signal more stable, reducing energy scattering and leakage, and ensuring efficient light energy transmission. In addition, the structure also provides more 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 optical fiber of the present invention can work under the condition of wide wavelength of 0.6-1.2μm, and can be applied to the transmission of high-power single-mode laser source in the 980nm band. The loss at 980nm wavelength is about 1.1144×10-9dB / km, and the dispersion flatness is close to 0, the nonlinear coefficient is about 0.26053 (W·km)-1, and the loss in the bending radius range of 5-15cm is 1.0976×10-9~8.4119×10-6dB / 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 drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0032] FIG. 1( a ) and FIG. 1( b ) are schematic cross-sectional views of a hollow-core antiresonant optical fiber according to the present invention;

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

[0034] Figure 3The electric field mode contour distribution diagram of the base film of the hollow-core anti-resonant 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 relationship diagram of the fundamental mode nonlinear coefficient of the present invention as the wavelength changes;

[0037] Figure 6 This is a relationship diagram of the fundamental mode dispersion coefficient of the present invention as it changes with wavelength;

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

[0039] Figure 8 The present invention provides a relationship diagram of the bending loss when bending in the Y direction at a wavelength of 0.98 μm as a function of the bending radius.

[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. Perfect matching 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 FIG. 1( 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, and the anti-resonance units include a circular dielectric tube with a nested structure and a fan-shaped dielectric tube 6 with a non-nested structure;

[0046] The circular medium tube includes 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 arranged outside 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 pipe and the fan-shaped medium pipe 6;

[0053] The circular medium pipes of the nested structure are evenly spaced and distributed between the fan-shaped medium pipes 6 .

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

[0055] The radius of the sector-shaped medium 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 medium tube 6 is silicon dioxide, and the interior thereof is air.

[0056] The radius of the first type of circular medium 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 circular medium tubes 2 are tangent to the second circular medium tube 3 , the angles between the third circular medium tube 2 at the center and the third circular medium tubes 2 on both sides thereof are both 90°, and the radius of the third 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 is the same, satisfying the anti-resonance condition:

[0060]

[0061] Wherein, λ represents the designed working 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 of circular medium tube 3 is 40 μm, and it is a concentric circle structure with the first type of circular medium tube 4;

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

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

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

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

[0071] In this embodiment, a perfect matching layer 7 is disposed 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] Embodiment 2:

[0073] This embodiment uses simulation tests to prove the superiority of the hollow-core antiresonant optical fiber in Embodiment 1;

[0074] The simulation was performed using finite element simulation software COMSOL Multiphysics, and theoretical calculations were performed using the finite element method combined with the perfect matching layer boundary absorption condition. The change relationship diagrams of the mode field distribution diagram, restrictive loss, dispersion, nonlinear coefficient, and bending loss of the hollow core antiresonant optical fiber in Example 1 were obtained through calculation.

[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 distribution of the electric field mode contour lines 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 anti-resonance 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 optical fiber and the wavelength (0.6-1.2μm). Figure 4 It can be seen that the limiting 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 less than the 0.2dB / km of traditional single-mode optical fiber. It can be seen that it plays an important role in the single-mode laser source of the 980nm band.

[0078] Figure 5 The figure shows the relationship between the nonlinear coefficient of the hollow core antiresonant 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 It can be seen that this optical fiber can improve transmission efficiency, support higher power, and maintain signal stability by reducing signal distortion and energy loss, 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 antiresonant fiber base film and the wavelength. Figure 6 The hollow-core antiresonant fiber can be seen in the dispersion variation in the 0.6-1.2μm band, and its group velocity dispersion value is close to zero. Near-zero dispersion fiber can effectively suppress 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 This is 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 dB / km level. This shows that the hollow-core antiresonant optical fiber in Example 1 has good bending resistance, can maintain stable optical signal transmission in complex wiring or narrow space, and 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 optical fiber described in the present invention has a spectral bandwidth of 0.6 μm (0.6-1.2 μm), can be used for optical signal transmission of a 980 nm 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 only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm pump light, characterized in that: The fiber core (5) comprises, from outside to inside, 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 (6) with a non-nested structure; 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 is composed of a plurality of anti-resonance units in an inner cladding (8).

2. A low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm 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: Wherein, λ represents the designed working 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. A low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm pump light according to claim 2, characterized in that: 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, and 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 made of silicon dioxide.

4. A low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm 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 arranged outside 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. A low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm pump light according to claim 4, characterized in that: There are no nodes between the circular medium pipe and the fan-shaped medium pipe (6); The circular medium tubes of the nested structure are distributed between the fan-shaped medium tubes (6) at equal intervals.

6. A low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm pump light according to claim 5, characterized in that: The fan-shaped medium tubes (6) are 90 degrees to each other, and the circular medium tubes in each two groups of nested structures are symmetrically located on both sides of the fan-shaped medium tubes (6), with an included angle of 45 degrees.

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

8. The low-loss bend-resistant hollow-core antiresonant optical fiber for 980nm pump light according to claim 7, characterized in that: The radius of the first type of circular medium tube (4) is 42.2 μm; 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); the angles between the third-type circular medium tube (2) located at the center and the third-type circular medium tubes (2) on both sides thereof are both 90°; and the radius of the third-type circular medium tube (2) is 12.2 μm.

9. Use of the hollow-core antiresonant optical fiber according to claim 8 in a 980nm single-mode laser source.

10. The use according to claim 9, comprising a hollow core anti-resonant optical fiber body, characterized in that: The working wavelength band of the hollow core anti-resonance optical fiber body is 0.6-1.2 μm.

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