A double-nested hollow anti-resonant optical fiber with an off-center structure

Abstract

This invention discloses a double-nested hollow-core antiresonant optical fiber with an off-center structure, relating to the field of optical communication technology. The double-nested hollow-core antiresonant optical fiber comprises, from the inside out: an air core, a first-stage cladding tube, a second-stage cladding tube, a third-stage cladding tube, and an outer cladding tube. The first-stage cladding tube is internally tangent and fixed to the outer cladding tube, the second-stage cladding tube is internally tangent and fixed to the first-stage cladding tube, and the third-stage cladding tube is internally tangent and fixed to the second-stage cladding tube. The optical fiber exhibits an off-center structure that is symmetrical vertically but asymmetrical horizontally. This invention proposes a hollow-core antiresonant optical fiber with specific structural parameters, which, compared to previous hollow-core antiresonant optical fibers, solves the problem of high bending loss that traditional hollow-core antiresonant optical fibers cannot effectively address at extremely short bending radii. This hollow-core optical fiber has low confinement loss and bending loss, and has significant application potential in particle sensing and micro-lasers.

Description

Technical Field

[0001] This invention belongs to the field of optical communication technology, and particularly relates to a double-nested hollow-core anti-resonant optical fiber with an off-center structure. Background Technology

[0002] Traditional solid-core optical fibers must overcome several inherent limitations in optical transmission, including a low material damage threshold, significant dispersion, and substantial nonlinear effects, especially in high-power laser transmission. Hollow-core antiresonant optical fibers, however, utilize the characteristic that most light (>99.99%) can propagate within an air core, thereby increasing the optical damage threshold of the silica material and significantly reducing nonlinear effects. This has generated considerable interest in the field of optical fiber communication over the past two decades.

[0003] Chinese patent CN221485655U proposes a novel hollow-core anti-resonant optical fiber with multiple anti-resonant layers, which maximizes the confinement of light waves within the fiber core, thereby achieving low confinement loss and high-purity single-mode output. However, its resonant layers use elliptical cladding tubes, which are extremely difficult to manufacture and not conducive to high-efficiency production.

[0004] Chinese patent CN111257992A discloses a hollow anti-resonant optical fiber with an off-center structure. Through an asymmetrical cladding structure design, it significantly reduces the bending loss of the fiber while improving its single-mode transmission characteristics. However, in its embodiments 1 and 2, only a single-layer cladding tube is used, resulting in poor loss limitation and reduced output power, thus affecting the output performance.

[0005] US Patent US2023040327A1 proposes an anti-resonant hollow fiber preform, which includes an outer cladding, multiple structural tubes and a central support tube. The central support tube and the outer cladding tube have multiple connection nodes, which affect the confinement loss and bending loss, resulting in poor output performance.

[0006] In summary, traditional solid-core optical fibers cannot effectively address the scientific problems of nonlinearity and thermal damage, especially in the field of high-power laser transmission. Existing technologies involving the design of hollow-core antiresonant fibers employ elliptical cladding tubes or other more complex cladding tube designs, which are extremely difficult to manufacture and hinder efficient production; or they use only a single-layer cladding tube, resulting in poor loss confinement and reduced output power; or there are multiple connection nodes between the outermost cladding tubes, affecting confinement loss and bending loss, leading to poor output performance. Therefore, current hollow-core antiresonant fibers cannot meet the practical requirements for lower transmission loss and lower bending loss under bending conditions.

[0007] This invention proposes a double-nested hollow-core anti-resonant optical fiber with an off-center structure, defines the structural characteristics of the hollow-core anti-resonant optical fiber, designs and manufactures hollow-core anti-resonant optical fibers with specific structural parameters, which not only achieves the goal of confining light of a specific wavelength in the air core for transmission, thus improving transmission loss, but also reduces bending loss under short bending radius conditions and increases output power. Summary of the Invention

[0008] The purpose of this invention is to provide a double-nested hollow anti-resonant optical fiber with a slightly off-center structure, in order to solve the problems mentioned in the background art, such as the inability of traditional solid optical fibers to effectively address nonlinearity and thermal damage, and the inability of existing hollow anti-resonant optical fibers to meet the practical needs of lower transmission loss and lower bending loss under bending conditions.

[0009] To achieve the above objectives, the present invention employs the following technical solution:

[0010] This invention proposes a double-nested hollow-core anti-resonant optical fiber with an off-center structure, which includes, from the inside out: an air core, several first-level cladding tubes, several second-level cladding tubes, several third-level cladding tubes, and an outer cladding tube; the double-nested hollow-core anti-resonant optical fiber has an off-center structure that is symmetrical vertically and asymmetrical horizontally.

[0011] Preferably, the first-stage cladding tube is internally fixed to the outer cladding tube, the second-stage cladding tube is internally fixed to the first-stage cladding tube, and the third-stage cladding tube is internally fixed to the second-stage cladding tube.

[0012] Preferably, the first-stage cladding tubes do not contact each other, forming a node-free annular cladding tube; the number of first-stage cladding tubes is 4 to 10, and the number of first-stage, second-stage, and third-stage cladding tubes is the same.

[0013] Preferably, the diameter of the air core is in the range of 20.50 to 40.50 μm.

[0014] Preferably, the radius of the first-stage cladding tube decreases sequentially from left to right, with a radius range of 9.41 to 25.99 μm.

[0015] Preferably, the ratio of the radius of the second-stage cladding tube to that of the first-stage cladding tube is in the range of 0.500 to 0.900, and the ratio of the radius of the third-stage cladding tube to that of the second-stage cladding tube is in the range of 0.280 to 0.450.

[0016] Preferably, the thickness of the first-stage cladding tube, the second-stage cladding tube, and the third-stage cladding tube is 0.38 to 0.64 μm within the first resonance range; or 0.85 to 1.25 μm within the second resonance range.

[0017] Preferably, the first-stage cladding tube, the second-stage cladding tube, and the third-stage cladding tube are all made of glass; the refractive index of the glass at a wavelength of 1550nm is in the range of 1.4315 to 1.4520, and the remaining part inside the outer cladding tube is filled with air.

[0018] Furthermore, the glass is made of quartz glass or other component glass.

[0019] Preferably, the anti-resonance region of the double-nested hollow anti-resonant optical fiber is in the 1150–1660 nm band, which is used to achieve low-loss transmission and bending resistance within its wavelength range.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] In this invention, the double-nested hollow-core antiresonant fiber is fixed by the first-stage cladding tube being internally tangent to the outer cladding tube, the second-stage cladding tube being internally tangent to the first-stage cladding tube, and the third-stage cladding tube being internally tangent to the second-stage cladding tube. Furthermore, the double-nested hollow-core antiresonant fiber exhibits a top-to-bottom symmetrical, left-to-right asymmetrical, off-center circular structure. This multi-layered nested structure design increases the number of resonant layers, reducing transmission loss. The use of circular cladding tubes simplifies manufacturing and increases application reliability. The first-stage cladding tubes are not in contact with each other, forming a node-free annular cladding tube, thus avoiding additional losses caused by nodes.

[0022] The designed and fabricated hollow-core antiresonant fiber with specific structural parameters not only achieves the goal of confining light of a specific wavelength within an air core for transmission, thus improving transmission loss, but also reduces bending loss under short bending radii, thereby increasing output power. This hollow-core fiber exhibits low confinement loss and bending loss, and has significant application potential in particle sensing and microlasers. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the cross-section of the double-nested hollow-core anti-resonant optical fiber with an off-center structure in this invention;

[0024] Figure 2 This is a schematic diagram of the cross-sections of the first-stage cladding tube, the second-stage cladding tube, and the third-stage cladding tube in this invention.

[0025] Figure 3 This is a schematic diagram of the confinement loss curve as a function of wavelength for the double-nested hollow anti-resonant optical fiber with an off-center structure in Embodiment 1 of the present invention.

[0026] Figure 4 This is a schematic diagram of the bending loss curve of the double-nested hollow anti-resonant optical fiber with a eccentric structure in Embodiment 1 of the present invention as a function of bending radius. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see Figure 1-2 This invention discloses a double-nested hollow-core antiresonant optical fiber with an off-center structure, comprising, from the inside out: an air core, a first-stage cladding tube, a second-stage cladding tube, a third-stage cladding tube, and an outer cladding tube. The first-stage cladding tube is internally tangent and fixed to the outer cladding tube, the second-stage cladding tube is internally tangent and fixed to the first-stage cladding tube, and the third-stage cladding tube is internally tangent and fixed to the second-stage cladding tube. The double-nested hollow-core antiresonant optical fiber has an off-center structure that is symmetrical vertically and asymmetrical horizontally. The diameter of the air core ranges from 20.50 to 40.50 μm, and the radius r of the first-stage cladding tube from left to right is... x The sizes decrease sequentially, ranging from 9.41 to 25.99 μm. The number of cladding tubes can be 4 to 10, and the first-stage cladding tubes are not in contact with each other, forming a node-free annular cladding tube. The ratio r of the radius of the second-stage cladding tube to that of the first-stage cladding tube is... y / r x The range is 0.500–0.900. The ratio r of the radius of the third-stage cladding tube to that of the second-stage cladding tube. z / r y The range is 0.280–0.450. The thickness of the first-stage cladding tube, second-stage cladding tube, and third-stage cladding tube can be within the first resonant range (0.38–0.64 μm) or the second resonant range (0.85–1.25 μm). The cladding tubes are all made of glass, which can be quartz glass or other types of glass. The refractive index n1 of the glass at a wavelength of 1550 nm ranges from 1.4315 to 1.4520, and the remaining portion is filled with air. The anti-resonance region of the double-nested hollow-core anti-resonant fiber is the 1150–1660 nm wavelength band. Within this wavelength range, the limiting loss is less than 0.10 dB / km. When the wavelength is 1550 nm, with a bending radius greater than 3 cm, the bending loss is less than 0.05 dB / km.

[0029] Example 1:

[0030] See Figure 1-2The double-nested hollow-core antiresonant fiber with an off-center structure comprises, from the inside out: an air core, a first-stage cladding tube, a second-stage cladding tube, a third-stage cladding tube, and an outer cladding tube. The first-stage cladding tube is internally tangent and fixed to the outer cladding tube, the second-stage cladding tube is internally tangent and fixed to the first-stage cladding tube, and the third-stage cladding tube is internally tangent and fixed to the second-stage cladding tube. There is no contact between the first-stage cladding tubes, forming a node-free annular cladding tube, thus avoiding additional losses caused by nodes. The double-nested hollow-core antiresonant fiber exhibits an off-center structure that is symmetrical vertically but asymmetrical horizontally.

[0031] In this embodiment, the first-stage cladding tube, the second-stage cladding tube, the third-stage cladding tube, and the outer cladding tube are all circular cladding tubes, which reduces the manufacturing difficulty and increases the reliability of the application; a multi-layer nested structure design is adopted, which reduces transmission loss by increasing the number of resonant layers.

[0032] Specifically, the diameter D of the air core __ The core is 25.50 μm, and the radius r of the first-stage cladding tube from left to right is... x1 r x2 r x3 The diameters are 16.36 μm, 14.23 μm, and 11.71 μm, and there is no contact between the first-stage cladding tubes, forming a nodeless annular cladding tube.

[0033] Specifically, the ratio r of the radius of the second-stage cladding tube to that of the first-stage cladding tube. y1 / r x1 r y2 / r x2 r y3 / r x3 The value is 0.800. The ratio r of the radius of the third-stage cladding tube to that of the second-stage cladding tube is... z1 / r y1 r z2 / r y2 r z3 / r y3 It is 0.425.

[0034] In this embodiment, the thickness t of the first-stage cladding tube, the second-stage cladding tube, and the third-stage cladding tube is 0.450 μm.

[0035] In this embodiment, the cladding tube is made of glass, which can be quartz glass or other types of glass. The refractive index n1 of the glass at a wavelength of 1550nm is 1.4440, and the rest is filled with air.

[0036] In this embodiment, the anti-resonance region of the double-nested hollow-core anti-resonant fiber is the 1150–1660 nm wavelength band. For details within this wavelength range, please refer to [reference needed]. Figure 3Within the anti-resonance wavelength range of 1150–1660 nm, the limiting loss is below 0.10 dB / km, i.e., 1.00 × 10⁻⁶. -4 dB / m. At a wavelength of 1550nm, with a bending radius greater than 3cm, the bending loss is less than 0.05dB / km. For details, please refer to [reference needed]. Figure 4 When the bending radius is greater than 3 cm, the bending loss is less than 0.05 dB / km, i.e., 5.00 × 10⁻⁶. -5 dB / m.

[0037] Example 2:

[0038] See Figure 1-2 The double-nested hollow-core antiresonant fiber with an off-center structure comprises, from the inside out: an air core, a first-stage cladding tube, a second-stage cladding tube, a third-stage cladding tube, and an outer cladding tube. The first-stage cladding tube is internally tangent and fixed to the outer cladding tube, the second-stage cladding tube is internally tangent and fixed to the first-stage cladding tube, and the third-stage cladding tube is internally tangent and fixed to the second-stage cladding tube. There is no contact between the first-stage cladding tubes, forming a node-free annular cladding tube, thus avoiding additional losses caused by nodes. The double-nested hollow-core antiresonant fiber exhibits an off-center structure that is symmetrical vertically but asymmetrical horizontally.

[0039] In this embodiment, the first-stage cladding tube, the second-stage cladding tube, the third-stage cladding tube, and the outer cladding tube are all circular cladding tubes, which reduces the manufacturing difficulty and increases the reliability of the application; a multi-layer nested structure design is adopted, which reduces transmission loss by increasing the number of resonant layers.

[0040] Specifically, the diameter D of the air core __ The core is 40.50 μm, and the radius r of the first-stage cladding tube from left to right is... x1 r x2 r x3 The diameters are 25.98 μm, 22.59 μm, and 18.59 μm, and there is no contact between the first-stage cladding tubes, forming a nodeless annular cladding tube.

[0041] Specifically, the ratio r of the radius of the second-stage cladding tube to that of the first-stage cladding tube. y1 / r x1 r y2 / r x2 r y3 / r x3 The value is 0.900. The ratio r of the radius of the third-stage cladding tube to that of the second-stage cladding tube is... z1 / r y1 r z2 / r y2 r z3 / r y3 It is 0.450.

[0042] In this embodiment, the thickness t of the first-stage cladding tube, the second-stage cladding tube, and the third-stage cladding tube is 1.25 μm.

[0043] In this embodiment, the cladding tube is made of glass, which can be quartz glass or other types of glass. The refractive index n1 of the glass at a wavelength of 1550nm is 1.4520, and the rest is filled with air.

[0044] In this embodiment, the anti-resonance region of the double-nested hollow-core anti-resonant fiber is in the 1360–1660 nm wavelength range. Within this wavelength range, the limiting loss is less than 0.09 dB / km. When the wavelength is 1550 nm, with a bending radius greater than 3 cm, the bending loss is less than 0.04 dB / km.

[0045] Example 3:

[0046] See Figure 1-2 The double-nested hollow-core antiresonant fiber with an off-center structure comprises, from the inside out: an air core, a first-stage cladding tube, a second-stage cladding tube, a third-stage cladding tube, and an outer cladding tube. The first-stage cladding tube is internally tangent and fixed to the outer cladding tube, the second-stage cladding tube is internally tangent and fixed to the first-stage cladding tube, and the third-stage cladding tube is internally tangent and fixed to the second-stage cladding tube. There is no contact between the first-stage cladding tubes, forming a node-free annular cladding tube, thus avoiding additional losses caused by nodes. The double-nested hollow-core antiresonant fiber exhibits an off-center structure that is symmetrical vertically but asymmetrical horizontally.

[0047] In this embodiment, the first-stage cladding tube, the second-stage cladding tube, the third-stage cladding tube, and the outer cladding tube are all circular cladding tubes, which reduces the manufacturing difficulty and increases the reliability of the application; a multi-layer nested structure design is adopted, which reduces transmission loss by increasing the number of resonant layers.

[0048] Specifically, the diameter D_core of the air core is 20.50 μm, and the radius r of the first-stage cladding tube from left to right is... x1 r x2 r x3 The diameters are 13.15 μm, 11.43 μm, and 9.41 μm, and there is no contact between the first-stage cladding tubes, forming a nodeless annular cladding tube.

[0049] Specifically, the ratio r of the radius of the second-stage cladding tube to that of the first-stage cladding tube. y1 / r x1 r y2 / r x2 r y3 / r x3 The value is 0.500. The ratio r of the radius of the third-stage cladding tube to that of the second-stage cladding tube is... z1 / r y1 r z2 / ry2 r z3 / r y3 It is 0.280.

[0050] In this embodiment, the thickness t of the first-stage cladding tube, the second-stage cladding tube, and the third-stage cladding tube is 0.380 μm.

[0051] In this embodiment, the cladding tube is made of glass, which can be quartz glass or other types of glass. The refractive index n1 of the glass at a wavelength of 1550nm is 1.4315, and the rest is filled with air.

[0052] In this embodiment, the anti-resonance region of the double-nested hollow-core anti-resonant fiber is in the 1150–1560 nm wavelength range. Within this wavelength range, the limiting loss is less than 0.10 dB / km. When the wavelength is 1550 nm, with a bending radius greater than 3 cm, the bending loss is less than 0.05 dB / km.

[0053] In summary, the double-nested hollow-core anti-resonant optical fibers in Examples 1-3 of this invention all satisfy the anti-resonance region of 1150–1660 nm. Within this wavelength range, the limiting loss is less than 0.10 dB / km. When the wavelength is 1550 nm, with a bending radius greater than 3 cm, the bending loss is less than 0.05 dB / km. Therefore, this invention designs and manufactures hollow-core anti-resonant optical fibers with specific structural parameters, achieving the goal of confining light of a specific wavelength within an air core for transmission, improving transmission loss, reducing bending loss under short bending radius conditions, and increasing output power.

[0054] The above description is only for the purpose of helping to understand the method and core essence of the present invention, but the scope of protection of the present invention is not limited thereto. For those skilled in the art, any equivalent substitutions or modifications made to the technical solution and inventive concept disclosed in the present invention within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A double-nested hollow-core anti-resonant optical fiber with an off-center circular structure, characterized in that, From the inside out, it includes: an air core, several first-level cladding tubes, several second-level cladding tubes, several third-level cladding tubes, and an outer cladding tube; the double-nested air-core anti-resonant fiber has a top-to-bottom symmetrical and left-to-right asymmetrical off-center structure; The first-stage cladding tube is internally tangentially fixed to the outer cladding tube, the second-stage cladding tube is internally tangentially fixed to the first-stage cladding tube, and the two third-stage cladding tubes are internally tangentially fixed to the second-stage cladding tube in opposite directions. The diameter of the air core ranges from 20.50 to 40.50 μm; The first-stage cladding tubes are not in contact with each other, forming a node-free annular cladding tube; The radius of the first-stage cladding tube decreases sequentially from left to right, ranging from 9.41 to 25.99 μm; The ratio of the radius of the second-stage cladding tube to that of the first-stage cladding tube ranges from 0.500 to 0.900, and the ratio of the radius of the third-stage cladding tube to that of the second-stage cladding tube ranges from 0.280 to 0.

450.

2. The double-nested hollow-core anti-resonant optical fiber with an off-center structure according to claim 1, characterized in that, The number of first-stage cladding tubes is 4 to 10, and the number of first-stage cladding tubes and second-stage cladding tubes is the same.

3. The double-nested hollow-core anti-resonant optical fiber with an off-center structure according to claim 1, characterized in that, The thickness of the first-stage cladding tube, the second-stage cladding tube, and the third-stage cladding tube is 0.38~0.64μm within the first resonance range; or 0.85~1.25μm within the second resonance range.

4. The double-nested hollow-core anti-resonant optical fiber with an off-center structure according to claim 1, characterized in that, The first-stage cladding tube, the second-stage cladding tube, and the third-stage cladding tube are all made of glass; the refractive index of the glass at a wavelength of 1550nm is in the range of 1.4315~1.4520, and the remaining part inside the outer cladding tube is filled with air.

5. The double-nested hollow-core anti-resonant optical fiber with an off-center structure according to claim 1, characterized in that, The anti-resonance region of the double-nested hollow anti-resonance optical fiber is the 1150~1660nm band.

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