Low-loss hollow-core anti-resonance optical fiber applied to ultraviolet band (320-390 nm)

Abstract

The invention relates to a low-loss hollow-core anti-resonance optical fiber. The optical fiber structurally comprises a negative curvature resonance tube unit, an air fiber core, an outer cladding sleeve, an elliptical combined tube unit and an elliptical tube unit, and all the negative curvature resonant tube units are nested and connected to the inner wall of the outer cladding sleeve around the fiber core, and form the low-loss hollow-core anti-resonant optical fiber together with the elliptical combined tube unit, the elliptical tube unit and the outer cladding sleeve. Light is bound in an optical fiber core area through anti-resonance, loss is reduced through the negative curvature resonance tube unit, and the minimum limiting loss of 0.02 dB / m is achieved. The method has a huge application value in the field of low-loss transmission of the ultraviolet band.

Description

Technical Field

[0001] The present application relates to a low-loss hollow-core anti-resonant optical fiber used in the ultraviolet band (320-390 nm), belonging to the field of optical communication and laser optoelectronic technology.

[0002] In recent years, with the rapid development of optical fiber technology, a new type of optical fiber, hollow core antiresonant fiber (HC-ARF), has gradually attracted widespread attention. Unlike traditional solid core optical fiber, the light of hollow core optical fiber mainly propagates in the hollow core, rather than in the glass material. This feature significantly reduces the interaction between light and the core material, thereby reducing loss, dispersion and nonlinear effects.

[0003] Antiresonant optical fiber achieves effective confinement of light through clever optical structure design. Its core is surrounded by an array of microstructured thin-walled tubes made of hollow or low-refractive index materials, which form an antiresonant effect. When light of a specific wavelength cannot couple with the resonant mode of these walls, the light is confined to the hollow core for transmission, preventing energy from leaking into the cladding.

[0004] Hollow-core antiresonant fiber avoids the absorption and scattering loss of light in glass materials, especially in the ultraviolet and mid-infrared bands, greatly reducing transmission loss compared to traditional optical fibers. Since most of the light is transmitted in the hollow core, HC-ARF exhibits extremely low nonlinear effects and dispersion, making it very suitable for applications such as high-power laser transmission and ultrashort pulse transmission.

[0005] HC-ARF limits the propagation path of light by designing an anti-resonant thin-walled tube structure outside the optical fiber core. The working principle is based on the anti-resonance effect: when the wavelength of light does not match the resonance mode of the wall tube, the light cannot enter the wall tube material, but is restricted to propagate in the hollow core. This design effectively avoids direct contact between light and glass materials, greatly reducing transmission losses.

[0006] Patent application number "CN215415988U" proposes an integrated anti-resonant hollow-core microstructure optical fiber. Through the stacking and nesting of hollow tube units, each hollow-core anti-resonant unit retains its own optical and physical properties, and the units do not interfere with each other, forming a state of strong and weak coupling. However, its structure is complex and not easy to implement.

[0007] Patent application number "CN202311046073.X" proposes a low-loss hollow-core negative curvature few-mode optical fiber, which connects the circular nested tube by setting a support sheet in the circular cladding tube, and reduces the coupling probability in the optical fiber transmission process through the combination of the hollow-core negative curvature optical fiber and the few-mode optical fiber, and finally reduces the limiting loss in the transmission process. Its working band is 1.2-1.7μm, and the working band of the present invention is 0.32-0.39μm.

[0008] Patent application number "CN201910685799.5" provides a hollow-core antiresonant optical fiber polarization filter, which separates the loss peaks in two polarization directions by filling metal, thereby filtering out the polarization fundamental mode in one direction, but its loss is higher than that of the present invention.

[0009] The document "WANG YY, GEROME F, HUMBERT G, et al. Low loss and broadb-and hollowcore photonic crystal fibers; proceedings of the Conference on Photonic and Phononic Properties of Engineered Nanostructures, San Francisco, CA, F2011Jan24-27, 2011[C]. 2011." proposed a cycloid Kagome hollow core optical fiber, which achieved a loss level of <102dB / m in the wavelength range of 0.6 to 2μm. The working band of this application is 0.32 to 0.39μm and the loss is much lower than that of the document.

[0010] In summary, hollow-core optical fiber produces high birefringence by introducing a change in the effective refractive index through the anti-cross-coupling effect of the core mode and the cladding mode. Currently, hollow-core optical fibers used in the ultraviolet band have defects such as complex structure, high manufacturing difficulty, and high limiting loss; therefore, it is very meaningful to design a hollow-core resonant optical fiber with lower limiting loss. Summary of the invention

[0011] In order to solve the above-mentioned problem, namely, the problem of excessive loss of hollow-core antiresonant optical fiber in the ultraviolet band, the purpose of the present invention is to provide a low-loss hollow-core antiresonant optical fiber for use in the ultraviolet band (320-390nm), which can be well used in the field of ultraviolet laser transmission.

[0012] The object of the present invention is achieved in that:

[0013] A low-loss hollow-core anti-resonance optical fiber applied in the ultraviolet band (320-390nm) comprises an air fiber core, a negative curvature resonance tube unit, an elliptical combination tube unit, an elliptical tube unit and an outer sleeve.

[0014] The elliptical combined pipe unit provided by the present invention comprises an outer portion composed of a plurality of elliptical combinations, wherein the sizes of the elliptical combined pipe units are consistent; the outer elliptical combined pipe is composed of a major semi-axis radius R a The range is 8~10μm, and the radius of the minor axis R bThe range is 4-5μm; the radius R of the tail circular structure is 8-9μm; the dielectric thickness t1 of the elliptical combined tube unit is 230-260nm; the dielectric material is SiO2; the external elliptical combined tube unit is composed of three identical elliptical tubes, and the elliptical tubes on both sides are rotated at an angle of 27° to 30° relative to the middle elliptical tube; the distance L between the internal rectangular tube unit and the center of the tail circular structure is 2.5-3μm. The elliptical combined tube unit rotates itself at a specific angle tr, and the specific angle tr ranges from 33.5° to 36.5°; the interval g between two adjacent elliptical combined tube units is consistent, and the interval g ranges from 0.5 to 1μm; the principle is to limit the transmission of light to the core area through anti-resonance to reduce transmission loss,

[0015] The negative curvature resonance unit provided by the present invention comprises an outer circular ring resonance tube and an inner nested circular ring. The radius R1 of each circular negative curvature resonance tube remains consistent, and the range of the radius R1 is 3 to 3.5 μm. The range of the radius R2 of the nested circular ring is 1.5 to 2 μm. The dielectric thickness t2 of the negative curvature resonance tube unit is in the range of 220 to 360 nm; SiO2 is selected as the dielectric material; the connection method of the circular negative curvature resonance tube and the nested circular ring is a nested connection, and the thickness at the connection node is maintained at t2±0.1t2. The negative curvature resonance tube unit can further reduce the loss of light through the anti-resonance effect, and the transmission loss can be changed by changing the number and position of the negative curvature tube units.

[0016] The elliptical tube unit provided by the present invention has a major semi-axis radius R3 in the range of 6 to 7 μm; a minor semi-axis radius R4 in the range of 4 to 5 μm; and a dielectric thickness t3 in the elliptical tube unit in the range of 240 to 270 nm.

[0017] The air core provided by the present invention is essentially an air hole surrounded by elliptical combined tube units; the length a of the air core is in the range of 10 to 14 μm, and the width b is in the range of 20 to 24 μm. The air core is the light-guiding area of ​​the hollow-core optical fiber, and the length a and width b are affected by the elliptical combined tube units; the length a and width b will affect the loss of the optical fiber.

[0018] The outer cladding sleeve provided by the present invention is essentially a protective layer on the outside of the hollow-core optical fiber, ensuring the stability and safety of the internal structure of the hollow-core optical fiber. To ensure a certain mechanical strength, the radius of the outer cladding sleeve is in the range of 25 to 80 μm, the thickness is in the range of 10 to 25 μm, and the material is SiO2.

[0019] The present invention has at least the following unique and significant advantages:

[0020] 1. The present application proposes a low-loss hollow-core anti-resonant optical fiber that can transmit in the ultraviolet band (320-390 nm). The anti-resonance effect can be used to achieve low-limit loss transmission of the optical fiber. The loss of the optical fiber can be changed by adjusting the wall thickness of the anti-resonance layer.

[0021] 2. The optical fiber structure of the present application is flexibly designed. The antiresonance wavelength of the hollow-core optical fiber is related to the quartz glass wall thickness of the antiresonance layer band. Therefore, the working bandwidth of the optical fiber can be adjusted by controlling the wall thickness, making the working band of the hollow-core optical fiber more flexible.

[0022] 3. The low-loss hollow-core antiresonant optical fiber described in this application has the characteristics of simple principle, stable performance, simple structure and very low loss, which overcomes the shortcomings of the existing technology and is suitable for application in the field of optical transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A two-dimensional end-face diagram of a low-loss hollow-core anti-resonant optical fiber for use in the ultraviolet band (320-390 nm) provided in this application; Figure 1 Various reference numerals shown in: elliptical combined tube unit S10, negative curvature resonance tube unit S20, air core S30, elliptical tube unit S40 and outer cladding tube S50;

[0024] Figure 2 A mode field diagram of a low-loss hollow-core antiresonant optical fiber applied to the ultraviolet band (320-390 nm) provided in an embodiment of the present application;

[0025] Figure 3 A limiting loss (CL) diagram of a low-loss hollow-core antiresonant optical fiber applied in the ultraviolet band (320-390 nm) provided in an embodiment of the present application; DETAILED DESCRIPTION

[0026] In order to make the present invention more clear and understandable, the specific implementation methods of the present invention will be described in detail with reference to the accompanying drawings.

[0027] The present invention illustrates the design advantages of the present application through the following embodiments:

[0028] Example

[0029] Please refer to Figure 1 , a detailed structural diagram of the hollow core optical fiber;

[0030] In this embodiment, the detailed structure of the hollow core optical fiber includes:

[0031] (1) Outer sheath casing;

[0032] The radius of the outer cladding sleeve is 26 μm, the thickness is 10 μm, and the material is SiO2.

[0033] (2) Negative curvature resonant tube unit;

[0034] The negative curvature resonance tube unit is composed of a circular negative curvature resonance tube and an internal nested circular ring; the radius R1 of the circular negative curvature resonance tube is: 3.2μm; the radius R2 of the nested circular ring is: 1.7μm; the dielectric thickness t2 of the negative curvature resonance tube unit is: 260nm; the connection method of the circular negative curvature resonance tube and the nested circular ring adopts a nested connection, and the thickness at the connection node is maintained at 260±26nm; the dielectric material is SiO2.

[0035] (3) Elliptical composite tube unit;

[0036] The radius of the major axis Ra of the ellipse formed by the external elliptical combined tube is: 8μm; the radius of the minor axis R b The radius R of the circular structure at the tail is 4 μm; the dielectric material is SiO2. The dielectric thickness t1 of the elliptical combined tube unit is 260 nm.

[0037] (4) Elliptical tube unit;

[0038] The long semi-axis radius R3 of the elliptical tube unit is: 7 μm; the short semi-axis radius R4 is: 5 μm; the dielectric thickness t3 of the elliptical combined tube unit is: 260 nm.

[0039] (4) Optical fiber core;

[0040] The optical fiber core is composed of an elliptical combined tube unit. The core length a is 12μm; the width b is 24μm; the material is air; please refer to the optical fiber core light guide effect diagram Figure 2 .

[0041] The low-loss hollow-core antiresonant optical fiber described in this application can achieve a minimum limiting loss of 0.02dB / m, please refer to Figure 3 ; This application can provide huge application value in the field of optical fiber transmission.

[0042] The specific parameters in the embodiments of the present invention may be modified according to actual needs, but the modifications and changes are within the scope of the present invention described in the claims.

Claims

1. A low-loss hollow-core anti-resonant optical fiber for use in the ultraviolet band (320-390 nm), the low-loss hollow-core anti-resonant optical fiber structure comprising: Air fiber core, negative curvature resonance tube unit, elliptical combination tube unit, elliptical tube unit and outer sleeve. The air fiber core is an air hole surrounded by elliptical combined tube units and is the main light-guiding area of ​​the air fiber core. The elliptical combination tube unit is a light beam unit inside the hollow core optical fiber, and is composed of an outer portion composed of a plurality of ellipses. The elliptical tube unit is an elliptical-shaped unit. The negative curvature resonance tube unit is composed of a circular negative curvature resonance tube and an internally nested circular ring, and is an important structure for achieving low transmission loss in the present invention. The outer cladding tube is a protective layer outside the high birefringence hollow core anti-resonance optical fiber.

2. The air core according to claim 1, characterized in that: The air fiber core is essentially an air hole surrounded by elliptical combined tube units; the length a of the air fiber core is in the range of 10 to 14 μm, and the width b is in the range of 20 to 24 μm.

3. The elliptical combined pipe unit according to claim 1, characterized in that: The sizes of the elliptical combined tube units are consistent; the outer elliptical combined tube has a long semi-axis radius R a The range is 8~10μm, and the radius of the minor axis R b The ellipse is in the range of 4 to 5 μm; the radius R of the tail circular structure is in the range of 8 to 9 μm; and the dielectric thickness t1 of the ellipse combined tube unit is in the range of 230 to 260 nm.

4. The elliptical combined pipe unit according to claim 1, characterized in that: The external elliptical combined tube unit is composed of three identical elliptical tubes, and the rotation angle of the elliptical tubes on both sides relative to the middle elliptical tube is 27° to 30°; the distance L between the internal rectangular tube unit and the center of the tail circular structure is in the range of 2.5 to 3 μm.

5. The elliptical combined pipe unit according to claim 1, characterized in that: The elliptical combined tube unit rotates itself at a specific angle tr, and the specific angle tr ranges from 33.5° to 36.5°; the interval g between two adjacent elliptical combined tube units is consistent, and the interval g ranges from 0.5 to 1 μm; the number of the elliptical combined tube units is fixed at 4.

6. The negative curvature resonance tube unit according to claim 1, characterized in that: The radius R1 of each circular negative curvature resonance tube is consistent, and the range of the radius R1 is 3 to 3.5 μm. The range of the radius R2 of the nested ring is 1.5 to 2 μm. The dielectric thickness t2 of the negative curvature resonance tube unit is in the range of 220 to 360 nm; the connection method of the circular negative curvature resonance tube and the nested ring is a nested connection, and the thickness at the connection node is maintained at t2±0.1t2.

7. The elliptical tube unit according to claim 1, characterized in that: The range of the long semi-axis radius R3 of the elliptical tube unit is 6-7 μm; the range of the short semi-axis radius R4 is 4-5 μm; the range of the medium thickness t3 of the elliptical tube unit is 240-270 nm.

8. A low-loss hollow-core antiresonant optical fiber for use in the ultraviolet band (320-390 nm) according to claim 1; achieving a minimum limiting loss of 0.02 dB / m and a lower surface scattering loss (SSL) level. The present invention can provide a medium for low-loss transmission in the ultraviolet band.

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