Anti-resonant hollow core fiber

Abstract

The present invention relates to an anti-resonance hollow core fiber (1000), comprising a fiber longitudinal axis (2300) and a fiber core radius R_Faser (2310), a fiber cladding (2000) having an inner bore (2200) of the cladding, and a plurality of anti-resonance units (3000), · each including an ARU external unit (3100) and an ARU internal unit (3400), · the ARU external unit (3100) designed in an arc shape and the ARU internal unit (3400) designed in an arc shape are connected to each other along two seam lines (3700, 3700') such that the ARU internal unit (3400) at least partially protrudes into a first interior (3170) of the ARU external unit (3100), the plurality of anti-resonance units (3000), The anti-resonance units (3000) are spaced apart from each other and are arranged at target positions on the inner side (2150) of the cladding without contacting each other, In at least one anti-resonance unit (3000), · an ARU arc unit (3900) is arranged in the first interior (3170), · the ARU arc unit (3900) is designed in a circular shape and · has a radius FB_R (3920), · the ARU arc unit (3900) is related to an anti-resonance hollow core fiber (1000) that is connected to the ARU internal unit (3400) along a contact seam (3730). According to the present invention, so as to apply to the ratio of twice the radius FB_R (3920) of the ARU arc unit to the fiber core radius R_Faser (2310), 【Equation 1】 JPEG2026511040000025.jpg10170 is provided.

Description

[Technical Field]

[0001] This invention relates to an anti-resonant hollow core fiber. [Background technology]

[0002] Hollow core fibers have a core with a vacuum cavity filled with gas or liquid. In hollow core fibers, the interaction between light and glass is less than in solid core fibers. Since the refractive index of the core is lower than that of the surrounding cladding, light transmission by total internal reflection is impossible. Hollow core fibers are classified into "photonic bandgap fibers" and "anti-resonant reflective fibers" depending on the physical mechanism of light transmission.

[0003] In a modified embodiment of a hollow-core fiber called an "anti-resonant hollow-core fiber" (ARHCF), the hollow core region is surrounded by an inner cladding region within which what is known as an anti-resonant unit (also known as an "anti-resonant element" or "ARU") is located. The walls of the anti-resonant unit, evenly distributed around the hollow core, can act as anti-resonant Fabry-Perot cavities, thereby reflecting incident light and thus enabling wave guidance within the fiber core.

[0004] This technology promises hollow core fibers with low optical attenuation, a very broad transmission spectrum (even in the UV or IR wavelength range), and low latency during data transmission.

[0005] International Publication No. 2022157179(A1) discloses an anti-resonant hollow core fiber in which a hollow core is surrounded by an inner cladding having anti-resonant units. These anti-resonant units have an outer ARU element and an inner ARU element inserted therein. Furthermore, arc elements can be arranged in the non-resonant elements. However, it has been found that, depending on the design of the arc elements, the transmission characteristics of the fundamental and higher-order modes are unsuitable, particularly for applications in the telecommunications field. In this regard, refer to International Publication No. 2022157179(A1), and its contents are incorporated herein by reference. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Industrial applications require anti-resonant hollow core fibers with low damping. Furthermore, there is a need for anti-resonant hollow core fibers that can be easily and mass-produced. This is the only way to keep the cost of anti-resonant hollow core fibers within a reasonable range. It is important to note that anti-resonant hollow core fibers that yield good results at the laboratory level are not necessarily suitable for large-scale applications.

[0007] The object of the present invention is to provide an anti-resonant hollow core fiber that overcomes the aforementioned drawbacks.

[0008] The objective of the present invention is to provide an anti-resonant hollow core fiber that can be manufactured accurately and reproducibly and exhibits low attenuation.

[0009] In particular, one object of the present invention is to provide an anti-resonant hollow core fiber having particularly low waveguide loss.

[0010] In particular, one objective of the present invention is to provide an anti-resonant hollow core fiber that efficiently attenuates higher-order modes. [Means for solving the problem]

[0011] At least a partial contribution to the realization of at least one of the foregoing objectives is made by the features of the independent claims. The dependent claims provide variants of preferred embodiments that contribute to at least a partial realization of at least one of the objectives.

[0012] The following variants of the embodiments contribute at least in part to realizing at least one of the foregoing objectives.

[0013] A variant of a first embodiment of an I1.I anti-resonant hollow-core fiber, comprising a fiber longitudinal axis and a fiber core radius R_Faser, a fiber cladding having an inner bore in the cladding, and a plurality of anti-resonant units, · each of which includes an ARU outer unit and an ARU inner unit, · the arcuate ARU outer unit and the arcuate ARU inner unit are connected to each other along two seam lines such that the ARU inner unit projects at least partially into the first internal space of the ARU outer unit, and a plurality of anti-resonant units, The anti-resonant units are spaced apart from each other and are arranged at a target position inside the cladding without contacting each other, · the ARU outer unit has a first circle radius FA_R and a first central angle FA_MW, · the ARU inner unit has a second circle radius FI_R and a second central angle FI_MW, <​​​​​​​​​​​​​· The ARU arc unit is a modification of the first embodiment of an anti-resonant hollow core fiber that is connected to the ARU inner unit along the contact seam.

[0014] This modification of the embodiment is characterized by the fact that the following,

[0015]

Number

[0016] I2.I A further modification of the anti-resonant hollow core fiber having the characteristics of the modification of the first embodiment is, for the ratio of twice the radius FB_R of the ARU arc unit to the fiber core radius R_Faser, the following, · 2*FB_R / R_Faser is 0.8 or more, particularly 0.9 or more, particularly 1.0 or more, and · 2*FB_R / R_Faser is 1.6 or less, particularly 1.5 or less, particularly 1.45 or less, characterized in that this applies.

[0017] I3.I A further modification of the anti-resonant hollow core fiber having the characteristics of the modification of the first or second embodiment is that the anti-resonant unit has a fiber space height FH_Z1, and for the ratio of the fiber space height FH_Z1 to the fiber core radius R_Faser, the following,

[0018]

Number

[0019] I4.I A further modification of the anti-resonant hollow core fiber having the characteristics of the third embodiment is, for the ratio of the fiber space height FH_Z1 to the fiber core radius R_Faser, the following, FH_Z1 / R_Faser must be 0.8 or higher, 0.85 or higher, especially 0.9 or higher, especially 0.95 or higher, especially 1.0 or higher, and FH_Z1 / R_Faser must be 1.4 or less, especially 1.35 or less, especially 1.3 or less, especially 1.2 or less. It is characterized by the fact that the following applies.

[0020] I5.I Further modifications of an anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments are as follows, regarding the ratio of the fiber space height FH_Z1 to twice the radius FB_R of the ARU arc unit:

[0021]

number

[0022] I6.I Further modifications of the anti-resonant hollow core fiber having the characteristics of the fifth embodiment are as follows, regarding the ratio of the fiber space height FH_Z1 to twice the radius FB_R of the ARU arc unit: FH_Z1 / (2*FB_R) is less than or equal to 1.2, especially less than or equal to 1.05, especially less than or equal to 1.0, especially less than or equal to 0.9, especially less than or equal to 0.85, and especially less than or equal to 0.8. FH_Z1 / (2*FB_R) must be 0.1 or greater, especially 0.125 or greater, especially 0.15 or greater, especially 0.2 or greater, especially 0.4 or greater, especially 0.5 or greater. It is characterized by the fact that the following applies.

[0023] I7.I Further embodiments of the anti-resonant hollow core fiber comprising any of the modifications of the preceding embodiments are characterized in that each anti-resonant unit has an ARU arc unit disposed in the first internal space of each ARU outer unit.

[0024] I8.I Further modifications of anti-resonant hollow core fibers having features of any of the modifications of the preceding embodiments are characterized in that the amount by which the first circle radius FA_R deviates from the second circle radius FI_R is less than 5%, in particular less than 3%, in particular less than 2%, and in particular less than 1% of the first circle radius FA_R.

[0025] I9.I Further modifications of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments include an anti-resonant hollow core fiber having three, four, five, six, seven, or eight anti-resonant units, and in particular an anti-resonant hollow core fiber having an odd number of anti-resonant units.

[0026] I10.I Further modifications of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments are characterized in that the anti-resonant units are asymmetrically arranged on the inner surface of the cladding.

[0027] I11.I Further embodiments of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments include at least one of the anti-resonant units having the following features: The ARU outer unit and / or the ARU inner unit and / or the ARU arc unit include amorphous solids, particularly glass, particularly quartz glass. The ARU outer unit and / or the ARU inner unit and / or the ARU arc unit are made of amorphous solid, in particular glass, in particular quartz glass. The ARU outer unit and / or the ARU inner unit and / or the ARU arc unit are made of the same material and, in particular, include or are composed of glass having a refractive index of at least 1.4, particularly 1.4 to 3, particularly 1.4 to 2.8, and The wall thicknesses of the ARU outer unit, the ARU inner unit, and the ARU arc unit are substantially the same. It is characterized by having at least one of the following.

[0028] I12.I Further embodiments of an anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments are characterized in that the waveguide loss of the anti-resonant hollow core fiber is at least 50 times smaller than the waveguide loss of an anti-resonant hollow core fiber without an arc unit, while all other design parameters remain the same.

[0029] I13.I Further embodiments of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments are as follows: • For transported wavelengths of 1.0 μm to 2.5 μm, the fundamental attenuation is less than 1.0 dB / km, especially less than 0.5 dB / km, especially less than 0.25 dB / km, especially less than 0.15 dB / km, and • For transported wavelengths up to 0.8 μm, the fundamental attenuation is less than 1 dB / km. It is characterized by having at least one of the following.

[0030] I14.I Further modifications of anti-resonant hollow core fibers having features of any of the modifications of the preceding embodiments are characterized in that the difference between the fundamental attenuation of a straight anti-resonant hollow core fiber and that of an anti-resonant hollow core fiber wound to a diameter of 10 mm is less than two orders of magnitude, in particular less than one order of magnitude, in particular less than half an order of magnitude.

[0031] I15.I Further embodiments of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments are as follows, with respect to the first radius FA_R and / or the second radius FI_R: This means that it is less than 30 μm, especially less than 20 μm, especially less than 17.5 μm, especially 16.5 μm or less, especially 15.75 μm or less, and / or This is larger than 5 μm, especially larger than 10 μm, especially 11.5 μm or larger, and especially 12.25 μm or larger. It is characterized by the fact that the following applies.

[0032] I16.I Further embodiments of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments include at least one ARU arc unit having the following features: The radius FB_R of the ARU arc unit is less than 15 μm, especially less than 12.5 μm, especially less than 11 μm, especially less than 9.5 μm. The radius FB_R of the ARU arc unit is greater than 0.75 μm, especially greater than 1 μm, and especially greater than 2.5 μm. It is characterized by having at least one of the following.

[0033] I17.I Further embodiments of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments include at least one ARU arc unit having the following features: • The first circle radius FA_R is less than 25 μm, and especially less than 15 μm. • The first circle radius FA_R is greater than 5 μm, and especially greater than 7 μm. • The first circle radius FA_R is 16.5 μm or less, and especially 15.75 μm or less. • The first circle radius FA_R is 11.5 μm or greater, especially 12.25 μm or greater. The first central angle FA_MW is less than 345°, especially less than 340°, especially less than 320°, especially less than 310°. The first central angle FA_MW is greater than 220°, especially greater than 250°, especially greater than 270°, and especially greater than 280°. It is characterized by having at least one of the following.

[0034] I18.I Further embodiments of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments include at least one ARU inner unit having the following features: The second circle radius FI_R is less than 25 μm, and especially less than 15 μm. • The second circle radius FI_R is greater than 5 μm, and especially greater than 7 μm. The second circle radius FI_R is 16.5 μm or less, and especially 15.75 μm or less. • The second circle radius FI_R is 11.5 μm or greater, especially 12.25 μm or greater. The second central angle FI_MW is less than 130°, especially less than 120°, especially less than 100°, and • The second central angle FI_MW is greater than 40°, and especially greater than 50°. It is characterized by having at least one of the following.

[0035] I19.I Further embodiments of the anti-resonant hollow core fiber having features of any of the modifications of the preceding embodiments include at least one anti-resonant unit having the following features: The wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit shall be 0.1 μm to 2.5 μm, particularly 0.15 μm to 1.5 μm, particularly 0.25 μm to 0.75 μm, particularly 0.35 μm to 0.65 μm, and particularly 0.5 μm. With respect to the 1550 nm signal wavelength in the first transmission window, the wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit shall be 0.35 μm to 0.65 μm, particularly 0.4 μm to 0.6 μm, particularly 0.5 μm. Regarding the signal wavelength of 1550 nm in the second transmission window, the wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit shall be 0.75 μm to 1.25 μm, particularly 0.9 μm to 1.1 μm, particularly 1 μm. It is characterized by including at least one of the following. [Modes for carrying out the invention]

[0036] Some of the features described are associated with the term “substantially”. The term “substantially” should be understood as meaning that, under actual conditions and manufacturing techniques, it is never possible to give precisely mathematically accurate interpretations of terms such as “superimposed,” “perpendicular,” “diameter,” or “parallelism,” and can only be given within a certain tolerance range for manufacturing errors. For example, “substantially parallel axes” means creating an angle of -5 to 5 degrees relative to each other, and “substantially equal volumes” means including a variation of up to 5 volume percent. For example, “a device substantially composed of quartz glass” means including a quartz glass content of 95% to 100% by weight. Furthermore, “substantially perpendicular” means including an angle of 85 to 95 degrees. Further details of the term “substantially” for some features are provided below.

[0037] The above objective is an anti-resonant hollow core fiber comprising a fiber longitudinal axis and fiber core radius R_Faser, a fiber cladding having an inner bore of the cladding, and a plurality of anti-resonant units, Each includes an ARU outer unit and an ARU inner unit, The arc-shaped ARU outer unit and the arc-shaped ARU inner unit comprise a plurality of anti-resonance units connected to each other along two seam lines such that the ARU inner unit protrudes at least partially into the first internal space of the ARU outer unit. The anti-resonance units are spaced apart from each other and positioned at target locations inside the cladding without touching each other. The ARU outer unit has a first circular radius FA_R and a first central angle FA_MW, The ARU inner unit has a second circular radius FI_R and a second central angle FI_MW, The amount by which the first circle radius FA_R deviates from the second circle radius FI_R is less than 10% of the first circle radius FA_R. • The first central angle FA_MW is less than 345° and greater than 275°. • The second central angle FI_MW is less than 195° and greater than 40°. In at least one anti-resonant unit, The ARU arc unit is placed in the first internal space, • The ARU arc unit is circular, ·Having radius FB_R, The ARU arc unit is connected to the ARU inner unit along the contact seam. This is achieved, at least partially, by anti-resonant hollow core fibers.

[0038] According to the present invention, the ratio of twice the radius FB_R of the ARU arc unit to the fiber core radius R_Faser is as follows:

[0039]

number

[0040] Twice the radius FB_R of the ARU arc unit corresponds to the diameter of the ARU arc unit. This type of anti-resonant hollow core fiber exhibits improved fundamental modes at shorter travel distances because the higher-order modes within the core couple particularly efficiently with the very lossy modes within the ARU arc unit.

[0041] "Basic mode" is understood to mean that the basic mode accounts for more than 95%, and especially more than 97.7%, of the power transported within the fiber core. In this respect, rapid achievement of the basic mode is equivalent to the higher-order modes traveling within the fiber core being attenuated to such an extent that more than 95%, and especially more than 97.7%, of the power transported within the fiber core becomes available in basic mode over short travel distances, particularly less than 20m, particularly less than 10m, and particularly less than 5m.

[0042] Generally, anti-resonant hollow core fibers (hereinafter also called ARHCFs) have a silica sheath and an air-filled cladding inner bore (also called an air core) that leads to a special optical propagation mechanism. ARHCFs follow the optical transmission mechanism of anti-resonant reflecting optical waveguiding (ARROW) and do not follow the principle of total internal reflection of single-mode fibers (SMFs).

[0043] The ARROW optical propagation mechanism utilizes coherent reflection at the air-silica interface, often in combination with the arrangement of anti-resonant units around a central hollow core, to effectively confine and guide forward-propagating light within the central hollow core. To represent the propagation of light within an ARHCF in simulations, a hollow core capillary with a regular silica cladding is chosen as a representative to describe the anti-resonance theory. A hollow core capillary with a regular ring cladding can be considered a radial Fabry-Perot resonant cavity. This Fabry-Perot resonant cavity allows for the transmission of optical frequencies within the fiber core that do not resonate with the core walls. These optical frequencies are reflected by the fiber core and propagate there with low loss. On the other hand, optical resonant frequencies cannot be confined within the fiber core and leak radially into the cladding region.

[0044] The losses in an ARHCF (Arrowhead-Reached Firmware) are mainly composed of scattering losses and waveguide losses. ● Scattering loss can be mainly divided into material scattering loss in all elements and surface scattering loss. Surface scattering losses are caused, in particular, by the surface roughness of the inner bore of the cladding and the outer unit of the ARU. These surface roughnesses are greatly influenced by the thermodynamic processes during fiber manufacturing. Material loss occurs in all areas of the ARHCF, including not only the hollow core but also the glass regions. Furthermore, the coating surrounding the silica cladding may also contribute to this. ○ Scattering loss is substantially unrelated to the design selected for ARHCF. ● Waveguide losses arise, in particular, from the arrangement of anti-resonant units around the central hollow core.

[0045] The transmission range of an ARHCF is spectrally defined by the anti-resonance region of the irregular cladding. The combination of anti-resonance and suppression of coupling between core and sheath modes is crucial to the optical transmission principle of ARHCFs.

[0046] Combining different modes with each other has a significant impact, for example, on the use of ARHCF in a data center. For the following explanation and / or simulation, the following modes were considered. • The basic mode within the core. Also known as core basic mode • Higher-order modes within the core. Also known as higher-order core mode (HOM). • In the simulation, only the second-order modes (i.e., the first-order modes, which are higher than the fundamental mode) were considered. • Modes within the ARU exterior unit Also known as anti-resonant unit mode or ARU mode. • The simulation only considers the basic mode within the ARU outer unit. • Modes within the ARU arc unit Also known as arc unit mode or DNE mode. • The simulation only considers the basic modes within the ARU arc unit.

[0047] Surprisingly, it was found that the geometric shape of the ARU arc unit can significantly influence the conduction behavior of the ARHCF. With the described dimensions of the ARU arc unit, it is possible to phase-match higher-order modes in the core with higher-order modes in the ARU arc unit. This effect is desirable, resulting in higher-order modes in the core coupling with more lossy arc unit modes. The resulting loss mechanism, in addition to the inherent waveguide loss, attenuates the higher-order modes in the core, and as a result, the ARHCF can operate effectively in the core fundamental mode.

[0048] Both the ARU outer unit and the ARU inner unit are arc-shaped. Deviations of the ARU outer unit wall and / or ARU inner unit wall from the ideal arc shape are based particularly on manufacturing-related variability. In particular, the first radius FA_R and / or the second radius FI_R do not deviate from the average first radius FA_R and / or the average second radius FI_R by more than 10%, particularly less than 5%, particularly less than 2.5%, both azimuthally across the arc and at points different in the axial direction of ARHCF, so that an elliptical course is formed.

[0049] The ARU arc unit is circular. The deviation of the radius FB_R of the ARU arc unit from the ideal circular shape is based particularly on manufacturing-related variability. In particular, the radius FB_R of the ARU arc unit does not deviate by more than 10%, particularly less than 5%, particularly less than 2.5%, both azimuthally across the circle and at different points in the axial direction of ARHCF, particularly so that an elliptical course is formed.

[0050] Further modifications of the embodiment are characterized in that the fiber core radius R_Faser is less than 30 μm, more particularly less than 25 μm, and more particularly less than 20 μm. Further modifications of the embodiment are characterized in that the fiber core radius is greater than 5 μm, more particularly greater than 10 μm, and more particularly greater than 15 μm. In particular, the anti-resonant hollow core fiber may have a fiber core radius R_Faser of 17.25 μm. The fiber core radius R_Faser described is a modification of the following advantageous embodiment. • The waveguide loss of the fundamental mode within the core decreases as the first circle radius FA_R increases, The bending sensitivity of ARHCF increases significantly as the first circle radius FA_R increases. This indicates.

[0051] Therefore, the stated fiber core radius R_Faser results in an ARHCF that exhibits both low waveguide loss in the fundamental mode and good bending sensitivity.

[0052] Further modifications of the embodiment involve the ratio of twice the radius FB_R of the ARU arc unit to the fiber core radius R_Faser, as follows: • 2*FB_R / R_Faser must be 0.8 or higher, especially 0.9 or higher, especially 1.0 or higher, and • 2*FB_R / R_Faser must be 1.6 or less, especially 1.5 or less, especially 1.45 or less. It is characterized by the fact that this applies.

[0053] This type of anti-resonant hollow core fiber has a particularly short travel distance to reach the fundamental mode.

[0054] Further modifications of the embodiment include an anti-resonance unit having a fiber space height FH_Z1, and the ratio of the fiber space height FH_Z1 to the fiber core radius R_Faser is as follows:

[0055]

number

[0056] Surprisingly, it was found that the geometric shape of the ARU arc unit can significantly influence the conduction behavior of the ARHCF when compared to the geometric shape of the ARU outer unit. In an ARHCF with at least one anti-resonant unit having specified parameters, higher-order modes in the core couple particularly effectively with ARU modes and / or DNE modes. As a result, the higher-order modes in the core are attenuated, and the hollow core fiber reverts to the fundamental mode at a shorter travel distance.

[0057] Further modifications of the embodiment involve the following regarding the ratio of the fiber space height FH_Z1 to the fiber core radius R_Faser: FH_Z1 / R_Faser must be 0.8 or higher, 0.85 or higher, especially 0.9 or higher, especially 0.95 or higher, especially 1.0 or higher, and FH_Z1 / R_Faser must be 1.4 or less, especially 1.35 or less, especially 1.3 or less, especially 1.2 or less. It is characterized by the fact that this applies.

[0058] The defined range allows for further optimization of the coupling between higher-order modes and ARU and / or DNE modes within the core. Therefore, the distance the hollow core fiber travels to enter the fundamental mode is further reduced.

[0059] Surprisingly, it was found that the geometric shape of the ARU arc unit affects not only the fundamental mode but also the attenuation of ARHCF. Further modifications of the embodiment involve the ratio of the fiber space height FH_Z1 to twice the radius FB_R of the ARU arc unit, as follows:

[0060]

number

[0061] Twice the radius FB_R of the ARU arc unit corresponds to the diameter of the ARU arc unit. A variation of this embodiment is characterized by particularly low damping in the fundamental mode.

[0062] Further modifications of the embodiment involve the following regarding the ratio of the fiber space height FH_Z1 to twice the radius FB_R of the ARU arc unit: FH_Z1 / (2*FB_R) is less than or equal to 1.2, especially less than or equal to 1.05, especially less than or equal to 1.0, especially less than or equal to 0.9, especially less than or equal to 0.85, and especially less than or equal to 0.8. FH_Z1 / (2*FB_R) must be 0.1 or greater, especially 0.125 or greater, especially 0.15 or greater, especially 0.2 or greater, especially 0.4 or greater, especially 0.5 or greater. It is characterized by the fact that this applies.

[0063] The specified interval allows for further optimization of the attenuation of the basic mode.

[0064] Further embodiments are characterized in that each anti-resonant unit has an ARU arc unit located in the first internal space of each ARU outer unit. By using one ARU arc unit within each anti-resonant unit of the hollow core fiber, the coupling between higher-order modes and DNE modes in the core is improved.

[0065] A variation of another embodiment is characterized in that the amount by which the first circle radius FA_R deviates from the second circle radius FI_R is less than 5%, particularly less than 3%, particularly less than 2%, and particularly less than 1% of the first circle radius FA_R. For manufacturing reasons, reducing the deviation between the first circle radius FA_R of the ARU outer unit and the second circle radius FI_R of the ARU inner unit is complex. Only by an efficient and precise hot process can tubes that satisfy these requirements be manufactured, particularly those made of quartz glass. This variation of the embodiment results in a further reduction of scattering loss in the ARHCF.

[0066] Further embodiments of the invention feature an anti-resonant hollow core fiber having three, four, five, six, seven, or eight anti-resonant units, and in particular, an anti-resonant hollow core fiber having an odd number of anti-resonant units. This embodiment allows for further optimization of the attenuation of the fundamental mode.

[0067] Further modifications of the embodiment are characterized by the asymmetric arrangement of anti-resonance units on the internal surface region of the cladding. As a result, higher-order modes in the core are attenuated, and the hollow core fibers enter the fundamental mode with a shorter travel distance.

[0068] Further embodiments include variations in which at least one of the anti-resonance units has the following features: The ARU outer unit and / or the ARU inner unit and / or the ARU arc unit include amorphous solids, particularly glass, particularly quartz glass. The ARU outer unit and / or the ARU inner unit and / or the ARU arc unit are made of amorphous solid, in particular glass, in particular quartz glass. The ARU outer unit and / or the ARU inner unit and / or the ARU arc unit are made of the same material and, in particular, include or are composed of glass having a refractive index of at least 1.4, particularly 1.4 to 3, particularly 1.4 to 2.8, and The wall thicknesses of the ARU outer unit, the ARU inner unit, and the ARU arc unit are substantially the same. It is characterized by having at least one of the following.

[0069] Modifications of these embodiments of the anti-resonant unit are optimized for low-loss signal transmission at wavelengths of 1.0 μm to 2.5 μm.

[0070] Further modifications of the embodiment are characterized in that the waveguide loss of the anti-resonant hollow core fiber is at least 50 times smaller than the waveguide loss of an anti-resonant hollow core fiber that does not have an arc unit but all other design parameters remain the same. The ARU arc unit described in the modifications of the embodiment is • The coupling between the basic mode and ARU mode and / or DNE mode within the core is minimal, but at the same time This enables higher-order modes within the core to effectively couple with the more lossy ARU and DNE modes.

[0071] This results in an ARHCF that, on the one hand, enters the basic mode with a short travel distance, and on the other hand, simultaneously has only low attenuation of the basic mode.

[0072] Further embodiments include an anti-resonant hollow core fiber with the following features: • For transported wavelengths of 1.0 μm to 2.5 μm, the fundamental attenuation is less than 1.0 dB / km, especially less than 0.5 dB / km, especially less than 0.25 dB / km, especially less than 0.15 dB / km, and • For transported wavelengths up to 0.8 μm, the fundamental attenuation is less than 1 dB / km. It is characterized by having at least one of the following.

[0073] This variant of the ARHCF is particularly well-suited for use in data centers due to its low attenuation of the basic mode.

[0074] Further embodiments are characterized in that the fundamental damping difference between a straight anti-resonant hollow core fiber and an anti-resonant hollow core fiber wound to a diameter of 10 mm is less than two orders of magnitude, more particularly less than one order of magnitude, and more particularly less than half an order of magnitude.

[0075] Further modifications of the embodiment include the following for the first circle radius FA_R: This means that it is less than 30 μm, especially less than 20 μm, especially less than 17.5 μm, especially 16.5 μm or less, especially 15.75 μm or less, and / or This is larger than 5 μm, especially larger than 10 μm, especially 11.5 μm or larger, and especially 12.25 μm or larger. It is characterized by the fact that the following applies.

[0076] This results in an ARHCF with only low attenuation in the fundamental mode.

[0077] Further embodiments include variations in which at least one ARU outer unit has the following features: • The first circle radius FA_R is less than 25 μm, and especially less than 15 μm. • The first circle radius FA_R is greater than 5 μm, and especially greater than 7 μm. • The radius of the first circle FA_R must be 16.5 mm or less, and especially 15.75 mm or less. • The first circle radius FA_R is 11.5 μm or greater, especially 12.25 μm or greater. The first central angle FA_MW is less than 345°, especially less than 340°, especially less than 320°, especially less than 310°. The first central angle FA_MW is greater than 220°, especially greater than 250°, especially greater than 270°, and especially greater than 280°. It is characterized by having at least one of the following.

[0078] This results in an ARHCF that, on the one hand, enters the basic mode with a short travel distance, and on the other hand, simultaneously exhibits only the low attenuation of the basic mode.

[0079] Further embodiments include variations in which at least one ARU internal unit has the following features: The second circle radius FI_R is less than 25 μm, and especially less than 15 μm. • The second circle radius FI_R is greater than 5 μm, and especially greater than 7 μm. The second circle radius FI_R is 16.5 μm or less, and especially 15.75 μm or less. • The second circle radius FI_R is 11.5 μm or greater, especially 12.25 μm or greater. The second central angle FI_MW is less than 130°, especially less than 120°, especially less than 100°, and • The second central angle FI_MW is greater than 40°, and especially greater than 50°. It is characterized by having at least one of the following.

[0080] This results in an ARHCF that, on the one hand, enters the basic mode with a short travel distance, and on the other hand, simultaneously exhibits only the low attenuation of the basic mode.

[0081] Further embodiments include variations in which at least one ARU arc unit has the following features: · The radius FB_R of the ARU arc unit is less than 15 μm, especially less than 12.5 μm, especially less than 11 μm, especially less than 9.5 μm. The radius FB_R of the ARU arc unit is greater than 0.75 μm, especially greater than 1 μm, and especially greater than 2.5 μm. It is characterized by having at least one of the following.

[0082] This allows for the development of basic ARHCF over short travel distances.

[0083] Further embodiments include variations in which at least one of the anti-resonance units has the following features: The wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit shall be 0.1 μm to 2.5 μm, particularly 0.15 μm to 1.5 μm, particularly 0.25 μm to 0.75 μm, particularly 0.35 μm to 0.65 μm, and particularly 0.5 μm. With respect to the 1550 nm signal wavelength in the first transmission window, the wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit shall be 0.35 μm to 0.65 μm, particularly 0.4 μm to 0.6 μm, particularly 0.5 μm. Regarding the signal wavelength of 1550 nm in the second transmission window, the wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit shall be 0.75 μm to 1.25 μm, particularly 0.9 μm to 1.1 μm, particularly 1 μm. It is characterized by having at least one of the following.

[0084] In particular, in ARHCFs with ARU arc units having a specified wall thickness, and especially at transported wavelengths of 1.0 μm to 2.5 μm, higher-order modes within the core couple particularly effectively with the more lossy DNE modes. As a result, the higher-order modes within the core are attenuated, and the hollow core fiber becomes the fundamental mode at a shorter travel distance.

[0085] The properties and features disclosed herein, individually or in combination with each other, may be essential to the various embodiments of the invention described in the claims.

[0086] The present invention is further illustrated by the following examples with reference to the drawings. The present invention is not limited to the drawings. [Brief explanation of the drawing]

[0087] The following is shown: [Figure 1] This shows the arc-shaped outer unit of the ARU. [Figure 2] This shows the arc-shaped inner unit of the ARU. [Figure 3] This shows a circular ARU arc unit. [Figure 4] This is a part of the anti-resonance unit, and is a magnified, detailed view of the seam line. [Figure 5] This is an anti-resonance unit, and a magnified detailed view of the contact seam. [Figure 6] This is a cross-sectional view of a portion of an anti-resonant hollow core fiber. [Figure 7] This is a cross-sectional view of an anti-resonant hollow core fiber. [Figure 8] This figure shows the effective mode refractive index Δneff(DNE) plotted against the ratio of twice the radius FB_R of the ARU arc unit to the fiber core radius R_Faser. [Figure 9] This figure plots the effective mode refractive index Δneff(ARU) against the ratio of the fiber space height FH_Z1 to the fiber core radius R_Faser. [Figure 10]This figure plots the difference in waveguide loss between fundamental and higher-order modes in the core against the ratio of the fiber spatial height FH_Z1 to the fiber core radius R_Faser. [Figure 11] This figure shows the waveguide loss for the fundamental mode as a function of the ratio of the fiber space height FH_Z1 to twice the radius FB_R of the ARU arc unit. [Figure 12] Another figure of the effective mode refractive index Δneff(DNE) plotted against the ratio of twice the radius FB_R of the ARU arc unit to the fiber core radius R_Faser.

[0088] Figure 1 shows a cross-section of the ARU outer unit 3100. The ARU outer unit 3100 is a tubular structure having an arc-shaped cross-section. The ARU outer unit 3100 extends along the first body longitudinal axis 3110. In Figure 1, the ARU outer unit 3100 therefore extends into the plane of the drawing.

[0089] The ARU outer unit 3100 has an ARU outer unit wall 3150. In particular, the ARU outer unit wall 3150 may include or be composed of a material that is transparent to the operating light of the optical fiber, such as glass, in particular doped or undoped quartz glass (SiO2).

[0090] In a modified example of one embodiment, the ARU outer unit wall 3150 has a wall thickness of 0.25 μm to 0.75 μm, particularly 0.35 μm to 0.65 μm, and particularly 0.5 μm.

[0091] As illustrated in the cross-section shown in Figure 1, the ARU outer unit 3100 has an arc-shaped cross-section. In the context of this invention, the term “arc” refers to a portion of a circular line. Two points on a circle divide the circular line into two arcs. In the context of this invention, an element is described as “arc-shaped” if its outline follows the path of one of the two arcs. To illustrate this, a first circle 2980 is drawn in Figure 1. This first circle 2980 is divided into two arcs by two intersecting lines QQ and RR. The cross-section of the ARU outer unit 3100 follows one of the two arcs.

[0092] Furthermore, an intersection line PP is drawn that passes through two points where the two intersection lines QQ and RR intersect with circle 2980. The first chord of the ARU outer unit 3100 lies on intersection line PP and is the distance delimited by intersection lines QQ and RR. The length of the first chord is 3290.

[0093] The ARU outer unit 3100 has a first circular radius FA_R3200. This first circular radius FA_R3200 represents the distance from the ARU outer unit wall 3150 to the first main body longitudinal axis 3110.

[0094] The ARU outer unit 3100 has a first segment height 3280. This first segment height 3280 is perpendicular to the first chord and represents the length of a straight line extending to the apex of the ARU outer unit wall 3150.

[0095] The ARU outer unit 3100 has a first central angle FA_MW3250. This first central angle FA_MW3250 represents the angle at which its vertex lies at the center of the first circle 2980 and its side intersects the boundary point of the arc (here, the point where the first circle 2980 intersects the intersection lines QQ and RR). A perfect circle has an angle value of 360°. Since the ARU outer unit 3100 is arc-shaped, the first central angle FA_MW3250 is less than 360°.

[0096] The ARU outer unit 3100 has a first internal space 3170 separated by the ARU outer unit wall 3150 and a first chord.

[0097] In a modified version of one embodiment, the ARU outer unit 3100 has the following features: • The radius of the first circle FA_R3200 is less than 25 μm, and especially less than 15 μm. • The first circle radius FA_R3200 is greater than 5 μm, and especially greater than 7 μm. • The radius of the first circle FA_R3200 is 16.5 μm or less, and especially 15.75 μm or less. • The radius of the first circle FA_R3200 must be 11.5 μm or greater, and especially 12.25 μm or greater. The first central angle 3250FA_MW is less than 345°, especially less than 340°, especially less than 320°, especially less than 310°. The first central angle 3250FA_MW may have at least one of the following conditions: greater than 220°, particularly greater than 250°, particularly greater than 270°, and particularly greater than 280°.

[0098] Figure 2 shows a cross-section of the ARU inner unit 3400. The ARU inner unit 3400 is a tubular structure with an arc-shaped cross-section. The ARU inner unit 3400 extends along the second body longitudinal axis 3410. In Figure 2, the ARU inner unit 3400 therefore extends into the plane of the drawing.

[0099] The ARU inner unit 3400 has an ARU inner unit wall 3450. In particular, the ARU inner unit wall 3450 may include or be composed of a material that is transparent to the operating light of the optical fiber, such as glass, in particular doped or undoped quartz glass (SiO2). In a modification of one embodiment, the ARU inner unit wall 3450 has a wall thickness of 0.25 μm to 0.75 μm, in particular 0.35 μm to 0.65 μm, in particular 0.5 μm.

[0100] The ARU inner unit 3400 has an arc-shaped cross-section. To illustrate this, a second circle 2990 is drawn in Figure 2. This second circle 2990 is divided into two arcs by two intersecting lines HH and II. The cross-section of the ARU inner unit 3400 follows one of the two arcs.

[0101] Furthermore, an intersection line GG is drawn that passes through two points where the two intersection lines HH and II intersect the second circle 2990. The second chord of the ARU inner unit 3400 lies on intersection line GG and is the area demarcated by intersection lines HH and II. The second chord length 3590 is the length of the second chord.

[0102] The ARU inner unit 3400 has a second segment height 3580. This second segment height 3580 is perpendicular to the second chord and represents the length of a straight line extending to the apex of the ARU inner unit wall 3450.

[0103] Furthermore, the ARU inner unit 3400 has a second circular radius FI_R3500. This second circular radius FI_R3500 represents the distance from the ARU inner unit wall 3450 to the second main body longitudinal axis 3410.

[0104] The ARU inner unit 3400 has a second central angle FI_MW3550. This second central angle FI_MW3550 represents the angle at which its vertex lies at the center of the second circle 2990 and its side intersects the boundary point of the arc (here, the point where the second circle 2990 intersects the intersection lines HH and II). A perfect circle has an angle value of 360°. Since the ARU inner unit 3400 is arc-shaped, the second central angle FI_MW3550 is less than 360°.

[0105] The ARU inner unit 3400 has a second internal space 3470 separated by the ARU inner unit wall 3450 and a second chord.

[0106] Figures 1 and 2 show cross-sections, i.e., axial plan views, of the ARU outer unit 3100 and the ARU inner unit 3400. In the two-dimensional views of the longitudinal axes 3110 and 3410 of the main body shown, the ARU outer unit 3100 and the ARU inner unit 3400 have arc-shaped cross-sections that correspond to tubular structural elements in the three-dimensional view.

[0107] The arcs of the ARU outer unit 3100 and / or ARU inner unit 3400 are substantially circular, and in particular, the first radius FA_R3200 and / or the second radius FI_R3500 do not vary by more than 10%, preferably more than 5%, and more preferably more than 3% over the circumference of the ARU outer unit 3100 and / or ARU inner unit 3400.

[0108] In a modified version of one embodiment, the ARU internal unit 3400 has the following features: The second circle radius FI_R3500 is less than 25 μm, and especially less than 15 μm. • The second circle radius FI_R3500 is greater than 5 μm, and especially greater than 7 μm. The second circle radius FI_R3500 must be 16.5 μm or less, and especially 15.75 μm or less. The second circle radius R_NE3500 must be 11.5 μm or greater, and especially 12.25 μm or greater. • The second central angle FI_MW3550 is less than 130°, especially less than 120°, especially less than 100°, and The second central angle FI_MW3550 may have at least one of the following conditions: greater than 40°, and especially greater than 50°.

[0109] Figure 3 shows the ARU arc unit 3900, which is a tubular structure. The ARU arc unit 3900 extends along the third longitudinal axis 3910 of the main body. In Figure 3, the ARU arc unit 3900 thus extends into the plane of the drawing.

[0110] The ARU arc unit 3900 has an arc wall 3950. In particular, the arc wall 3950 may include or be composed of a material that is transparent to the operating light of the optical fiber, such as glass, especially doped or undoped quartz glass (SiO2).

[0111] In a modified example of one embodiment, the arcuate wall 3950 has a wall thickness of 0.25 μm to 0.75 μm, particularly 0.35 μm to 0.65 μm, and particularly 0.5 μm.

[0112] The ARU arc unit 3900 has a radius FB_R3920. This radius FB_R3920 represents the distance between the arc wall 3950 and the first longitudinal axis 3910 of the main body. The ARU arc unit 3900 has a third internal space 3970 separated by the arc wall 3950.

[0113] In a modified version of one embodiment, the ARU arc unit 3900 has the following features: The radius FB_R3920 of the ARU arc unit is less than 15 μm, especially less than 12.5 μm, especially less than 11 μm, especially less than 9.5 μm. The radius FB_R3920 of the ARU arc unit may be greater than 0.75 μm, particularly greater than 1 μm, and particularly greater than 2.5 μm, or at least one of these conditions.

[0114] Figure 4 shows a portion of the hollow core fiber comprising the ARU outer unit 3100 and the ARU inner unit 3400 as shown in Figures 1 and 2. The ARU outer unit 3100 has a first internal space 3170, at least partially separated by the ARU outer unit wall 3150. The arc-shaped ARU inner unit 3400 projects at least partially into the first internal space 3170. This means that in cross-section, the ARU inner unit 3400 extends substantially above the first chord of the ARU outer unit 3100.

[0115] The arc-shaped outer ARU unit 3100 and the arc-shaped inner ARU unit 3400 are connected to each other along two connecting seams 3700, 3700' which are positioned substantially parallel to the longitudinal axis 3110 of the first body. In particular, this joining can be achieved by a hot process.

[0116] To illustrate this, the area around connection seam 3700 is shown in a magnified view in Figure 4. The connection is · The first endpoint of the ARU outer unit wall 3150 of the ARU outer unit 3100, - Formed between the ARU inner unit 3400 and the second endpoint of the ARU inner unit wall 3450.

[0117] Since Figure 4 shows a cross-section, the two connection seams 3700 and 3700' in the three-dimensional hollow core fiber 1000 extend into the plane of the drawing.

[0118] Due to manufacturing-related variations, the first endpoint of the ARU outer unit wall 3150 may not precisely coincide with the second endpoint of the ARU inner unit wall to form the connecting seams 3700, 3700', particularly in some areas. In particular, two deviations from this positioning of the ARU inner unit 3400 may occur due to manufacturing-related variations.

[0119] 1. The first endpoint (a specific region) of the ARU outer unit wall 3150 can be positioned on the ARU inner unit wall 3450 of the ARU inner unit 3400, and thus the ARU inner unit 3400 can partially protrude from the first internal space 3170. In this case, the ARU inner unit 3400 can be joined only partially to the inner surface 2150 of the cladding 2000. The latter may depend on the proportion of the second central angle FI_MW that protrudes from the first internal space 3170. In cross-section, the second central angle FI_MW 3550 of the ARU inner unit 3400 may protrude from the first internal space 3170 by a particularly small percentage, particularly 2.5%, or particularly 1%. The smaller the proportion of the second central angle FI_MW 3550 that protrudes from the first internal space 3170, the better the fundamental mode of ARHCF.

[0120] 2. The second endpoint (a specific region) of the ARU inner unit wall 3450 can be positioned on the ARU outer unit wall 3150 of the ARU outer unit 3100, and thus the ARU inner unit 3400 can be fully fitted into the first internal space 3170. In this case, the ARU outer unit 3100 can be joined only partially to the inner surface 2150 of the cladding 2000. The latter depends on the percentage of the second central angle FI_MW3550 that is theoretically further required to establish contact between the first and second endpoints. In particular, in cross-section, a percentage of 5% or less of the second central angle FI_MW3550, especially 2.5% or less, especially 1% or less may be further required to theoretically establish contact between the first and second endpoints. The smaller the percentage of the second central angle FI_MW3550 that is required, the better the basic mode of ARHCF.

[0121] Figure 5 shows an anti-resonant unit 3000 comprising an arc-shaped outer ARU unit 3100 and an arc-shaped inner ARU unit 3400 as shown in Figure 2, with the addition of an ARU arc unit 3900 as shown in Figure 3. The ARU arc unit 3900 functions as an anti-resonant element to reduce the attenuation of fundamental modes and / or waveguide losses, and, if properly designed, can increase the attenuation of higher-order modes within the core.

[0122] The arc-shaped ARU inner unit 3400 and the ARU arc unit 3900 are connected to each other along a contact line 3730 which is positioned substantially parallel to the longitudinal axis 3110 of the first body. In particular, this joining can be achieved by a hot process. In a modification of one embodiment, the contact line 3730 is positioned on the ARU inner unit 3400 such that the distance between the contact line 3730 and the first chord is as large as possible.

[0123] The ARU outer unit 3100 has a first internal space 3170 which is at least partially separated by the ARU outer unit wall 3150. The ARU arc unit 3900 is placed in the first internal space 3170.

[0124] As shown in Figure 5, the anti-resonant unit 3000 has a fiber space height FH_Z1 3800. This fiber space height FH_Z1 3800 represents the shortest length of the straight line extending between the vertex of the ARU outer unit 3100 and the vertex of the ARU arc unit 3900. In a modification of one embodiment, the fiber space height FH_Z1 3800 is perpendicular to the first chord and can extend to the vertex of the ARU outer unit wall 3150. The fiber space height FH_Z1 3800 represents the free space between the ARU outer unit 3100 and the ARU arc unit 3900.

[0125] The three longitudinal axes of the ARU outer unit 3100, the ARU inner unit 3400, and the ARU arc unit 3900 can be substantially located on a straight line 3750. The lateral deviation of each of these longitudinal axes from the straight line 3750 is limited in particular by manufacturing tolerances. In particular, the deviation is less than 5%, in particular less than 2.5%, and in particular less than 1% of the first circular radius FA_R.

[0126] To illustrate this, the area around connection seam 3730 is shown in a magnified view in Figure 5. The connection is • A point on the ARU inner unit wall 3450 of the ARU inner unit 3400, - Formed between a point on the arc wall 3950 of the ARU arc unit 3900.

[0127] Since Figure 5 shows a cross-section, the contact seam 3730 in the three-dimensional anti-resonance unit 3000 extends into the plane of the drawing.

[0128] Figure 6 shows a cross-sectional view of a portion of the anti-resonant hollow core fiber 1000. A portion of the anti-resonant hollow core fiber 1000 between two intersection lines AA and BB is shown. The anti-resonant hollow core fiber 2400 has a cladding 2000. The cladding 2000 can consist of an elongated sheath tube combined with an elongated cladding material. In the modified embodiment shown, the cladding material and the sheath tube material are identical, so the transition between the two materials is not shown. The cladding 2000 has an inner cladding radius of 2250, which results from the distance between the fiber longitudinal axis 2300 of the anti-resonant hollow core fiber 1000 and the inner surface 2150. The anti-resonant unit 3000 is positioned on the inner surface 2150 and integrally bonded to the inner surface 2150 of the cladding 2000.

[0129] Both the ARU outer unit 3100 and the ARU inner unit 3400 are arc-shaped. Deviations of the ARU outer unit wall 3150 and / or ARU inner unit wall 3450 from the ideal arc shape are based particularly on manufacturing-related variability. In particular, the first circle radius FA_R3200 and / or the second circle radius FI_R3500 in the ARHCF do not deviate by more than 10%, particularly less than 5%, particularly less than 2.5%, both azimuthally across the arc and at different points in the axial direction of the ARHCF, so as to form an elliptical course.

[0130] The ARU arc unit 3900 is circular. The deviation of the radius FB_R3920 of the ARU arc unit 3900 from the ideal circular shape is based particularly on manufacturing-related variability. In particular, the radius FB_R3920 of the ARU arc unit 3900 does not deviate by more than 10%, particularly less than 5%, particularly less than 2.5%, both azimuthally across the circle and at different points in the axial direction of ARHCF, so that an elliptical course is formed.

[0131] Figure 7 shows a cross-sectional view of an anti-resonant hollow core fiber 1000. The anti-resonant hollow core fiber 1000 has a hollow core 2470. Electromagnetic waves can propagate through the hollow core 2470. The hollow core fiber 1000 has a core radius 2310, which arises from the shortest distance between the longitudinal axis 2300 of the anti-resonant hollow core fiber 1000 and the ARU outer unit 3100. Figure 7 shows the arrangement of multiple anti-resonant units 3000 (also called ARUs) on the inner surface 2150 that divides the hollow core 2470. In one embodiment, the anti-resonant hollow core fiber 1000 may have three, four, five, six, seven, or eight anti-resonant units 3000. In Figure 7, the anti-resonant hollow core fiber 1000 has six anti-resonant units 3000. In a modified version of this embodiment, the anti-resonance unit 3000 is asymmetrically arranged on the inner surface 2150 of the cladding 2000.

[0132] The anti-resonant hollow core fiber 1000 shown in Figure 7 is characterized in that the amount by which the first circle radius FA_R3200 deviates from the second circle radius FI_R3500 is less than 10% of the first circle radius FA_R3200.

[0133] In the anti-resonant hollow core fiber 1000 shown in Figure 7, the ARU outer unit 3100 and / or ARU inner unit 3400 and / or ARU arc unit 3900 may contain or be composed of quartz glass. Furthermore, the wall thickness of the ARU outer unit 3100 and / or ARU inner unit 3400 and / or ARU arc unit 3900 can be designed based on the wavelength transported within the ARHCF. Thus, the anti-resonant hollow core fiber 1000 can have wall thicknesses of 0.35 μm to 0.65 μm, particularly 0.4 μm to 0.6 μm, for a signal wavelength of 1,550 nm in the ARU outer unit 3100 and / or ARU inner unit 3400 and / or ARU arc unit 3900. When the anti-resonant hollow core fiber 1000 operates at a signal wavelength of 1,550 nm within the second transmission window, the wall thickness of the ARU outer unit 3100 and / or the ARU inner unit 3400 and / or the ARU arc unit 3900 may be 1.25 μm to 0.75 μm, particularly 1.1 μm to 0.9 μm.

[0134] In particular, the wall thicknesses of the ARU outer unit 3100, the ARU inner unit 3400, and the ARU arc unit 3900 may be substantially the same. Specifically, the wall thicknesses of the ARU outer unit 3100, the ARU inner unit 3400, and the ARU arc unit 3900 may differ from the wall thickness of the ARU outer unit 3100 by less than 10%, and especially less than 5%.

[0135] The anti-resonant hollow core fiber 1000 shown in Figure 7 may be further characterized in that the fiber core radius R_Faser2310 is less than 30 μm, particularly less than 25 μm, and particularly less than 20 μm. Furthermore, the anti-resonant hollow core fiber 1000 may be characterized in that the fiber core radius R_Faser2310 is greater than 5 μm, particularly greater than 10 μm, and particularly greater than 15 μm. In particular, the anti-resonant hollow core fiber 1000 may have a fiber core radius R_Faser2310 of 17.25 μm. In particular, the anti-resonant hollow core fiber 1000 may have a fiber core radius R_Faser2310 of 17.25 μm.

[0136] In a modified embodiment of the anti-resonant hollow core fiber 1000, the first circle radius FA_R3200 may be 15.75 μm or less and 12.25 μm or more.

[0137] Figure 7 shows some parameters that describe some arrangements of the geometric shape of the anti-resonant hollow core fiber 1000. The diameter of the ARU arc unit 3900 is FB_D3980, that is, twice the radius of the ARU arc unit 3900, FB_R3920. ·The fiber space height FH_Z1 3800 of the anti-resonant unit 3000 represents the shortest distance between the vertex of the ARU outer unit 3100 and the vertex of the ARU arc unit 3900, and The core radius 2310 of the anti-resonant hollow core fiber 1000 represents the shortest distance between the longitudinal axis 2300 and the ARU outer unit 3100.

[0138] Figures 8–12 show the simulation results for an anti-resonant hollow core fiber 1000 with an ARU arc unit. The finite element method COMSOL mode solver was used for numerical calculations. A perfectly matched layer (PML) with a thickness of 10 μm was implemented at the outer interface of the optical fiber to investigate the radiation characteristics of the waveguide structure by absorbing the radially emitted energy.

[0139] The starting point of the simulation was an anti-resonant hollow core fiber 1000 configured similarly to the anti-resonant hollow core fiber 1000 shown in Figure 7. This anti-resonant hollow core fiber 1000 comprises a fiber cladding 2000 having a fiber core radius R_Faser 2310. Furthermore, the anti-resonant hollow core fiber 1000 comprises six anti-resonant units 3000. Each unit comprises an ARU outer unit 3100 and an ARU inner unit 3400. The arc-shaped ARU outer unit 3100 and the arc-shaped ARU inner unit 3400 are interconnected along two seam lines 3700, 3700' such that the ARU inner unit 3400 protrudes at least partially into the first internal space 3170 of the ARU outer unit 3100.

[0140] In each of the anti-resonance units 3000, The ARU arc unit 3900 is located in the first internal space 3170. The ARU arc unit 3900 is circular, The ARU arc unit 3900 is connected to the ARU inner unit 3400 along the contact seam 3730.

[0141] The anti-resonant unit has a wall thickness of 500 nm, which is particularly suitable for a wide transmission range (first transmission bandwidth) around the signal wavelength of 1,550 nm. Two designs were used to simulate the anti-resonant hollow core fiber 1000. These two designs differ in the following respects. In design 1, the first circle radius FA_R is 15.75 μm. In design 2, the radius FA_R of the first circle is 12.25 μm.

[0142] The second circle radius FI_R corresponds to the first circle radius FA_R. All other parameters were identical in both designs. These and other parameters for the simulated anti-resonant hollow core fiber 1000 can be found in Table 1.

[0143] [Table 1]

[0144] For the simulation, the following modes were considered: • The basic mode within the core. Also known as core basic mode • Higher-order modes within the core. Also known as Higher-Order Core Mode (HOM) · In the simulation, only the second mode (i.e., the first mode above the fundamental mode) was considered. This is because modes higher than the third typically have even higher waveguide losses and are thus less relevant when considering the fundamental mode, which is mainly determined by the power and waveguide losses in the second mode. · Mode within the ARU outer unit · Also called the anti-resonance unit mode or ARU mode that propagates within the first internal space 3170 of the ARU outer unit · In the simulation, only the fundamental mode within the ARU outer unit was considered. · Mode within the ARU arc unit · Also called the arc unit mode or DNE mode that propagates within the third internal space 3970 of the ARU arc unit · In the simulation, only the fundamental mode within the ARU arc unit was considered.

[0145] The parameters used in FIGS. 8 to 11 are described in more detail below.

[0146] Effective mode refractive index n eff represents the phase velocity of each mode in the propagation direction along the fiber axis through the relationship v phase = c / n eff where c represents the speed of light in vacuum.

[0147] Effective mode refractive index difference Δn eff (ARU) represents the difference between the effective mode refractive index of the higher-order mode in the core and the effective mode refractive index of the anti-resonance mode (ARU mode). Δn eff (ARU) = n eff,core-HOM - n eff,ARU mode

[0148] Δn eff (DNE) equivalently exists as the difference between the effective mode refractive index of the higher-order mode in the core and the effective mode refractive index of the arc unit mode (DNE mode). Δn eff (DNE) = n eff,core-HOM - neff,DNE mode

[0149] The difference Δn in both cases eff When the phase is close to zero, each mode propagates at approximately the same phase propagation rate and can therefore couple coherently (in phase), which leads to effective energy coupling. In this case, the energy of the higher-order core modes couples to the lossy ARU mode or DNE mode. Thus, energy is transferred from the higher-order core modes, which leads to an improvement in the fundamental mode.

[0150] In the simulation, the effective mode refractive index n eff These were extracted from the propagation constant β of each mode. Mode "j" is the solution to the physical system of equations. E j (x,y,z,t) = amplitude j (x,y)*exp(i*(β j *z-ω*t)) Here, ·E j (x,y,z,t) represents the electric field distribution in three spatial dimensions x,y,z at time t. ·amplitude j (x,y) represents the lateral electric field distribution.

[0151] Therefore, the propagation constant β represents the phase characteristics of wave propagation along the fiber axis z. Based on the wavelength λ of light, the n of mode "j" eff It can be obtained directly from β. β j = 2*pi / λ*n eff,j

[0152] Propagation constant of the j-th mode (β j ) is generally a complex parameter as a solution to the simulation. The real part yields n_eff,j, but the waveguide loss determined for the core mode can be derived from the imaginary part. Therefore, the parameter β j This includes all the important characteristics here.

[0153] The aforementioned drawbacks of known ARHCFs are overcome, especially when high-speed fundamental modes are achieved. This is intended to mean that higher-order modes are attenuated within the core, and the anti-resonant hollow core fiber behaves effectively like the fundamental mode after shorter travel distances. The shorter this travel distance, the higher the fundamental mode. The physical background is that the energy of higher-order modes within the core couples to the more lossy ARU mode and / or DNE mode. This means that higher-order modes no longer negatively impact optical signal transmission within the core.

[0154] Simulations of the anti-resonant hollow core fiber 1000 surprisingly showed that the geometric shape of the ARU arc unit 3900 influences the fundamental modes. In particular, the ratio of twice the radius of the ARU arc unit FB_R3920 to the fiber core radius R_Faser2310 was found to be important.

[0155] In Figure 8, the effective mode refractive index difference Δneff(DNE) is plotted against the ratio of twice the radius of the ARU arc unit FB_R3920 to the fiber core radius R_Faser2310. • The results shown as dots represent Δn based on Design 1. eff (DNE) is plotted, • The result shown as a star is Δn based on design 2. eff (DNE) is plotted.

[0156] Curve fitting was used to fit the curve to both sets of results.

[0157] Δn, which has a small magnitude, exhibits effective energy coupling via adapted phase propagation velocities between related modes. eff (DNE) is desirable. The difference between design 1 and design 2 is Δn each time. eff (DNE) does not result in strong variability in the calculated results. Rather, the two curve fits are very close to each other, or even above each other. Small Δn eff(DNE) specifically for the first circular radius FA_R of 12.25 μm to 15.75 μm, the ratio of twice the radius FB_R3920 of the ARU arc unit to the fiber core radius R_Faser2310 is as follows:

[0158]

number

[0159] Furthermore, variations of this embodiment allow for greater flexibility in optimally adjusting the coupling between the ARU mode and / or DNE mode and the higher-order core mode by specifying a rational geometric space.

[0160] Further positive effects on the difference in phase propagation velocity are as follows, regarding the ratio of twice the radius of the ARU arc unit FB_R3920 to the fiber core radius R_Faser2310: • 2*FB_R / R_Faser must be 0.8 or higher, especially 0.9 or higher, especially 1.0 or higher, and This can be achieved if 2*FB_R / R_Faser is 1.6 or less, especially 1.5 or less, and especially 1.45 or less.

[0161] During simulations of the anti-resonant hollow core fiber 1000, it was surprisingly shown that the geometry of the ARU arc unit 3900 in relation to the geometry of the ARU outer unit influences the fundamental mode. In particular, the ratio of the fiber space height FH_Z1 3800 to the fiber core radius R_Faser2310 is important. Figures 9 and 10 show the positive characteristics of this ratio.

[0162] In Figure 9, the effective mode refractive index Δneff(ARU) for the two designs is plotted against the ratio of the fiber space height FH_Z1 3800 to the fiber core radius R_Faser2310. • The results shown as dots represent Δn based on Design 1. eff(ARU) is plotted, • The result shown as a star is Δn based on design 2. eff (ARU) is plotted.

[0163] Curve fitting was used to fit the curve to both sets of results.

[0164] As shown in Figure 9, in design 1, the fundamental mode is achieved at a smaller ratio of fiber space height to fiber core radius than in design 2. Regarding this point, the ratio of fiber space height FH_Z1 3800 to fiber core radius R_Faser2310 is as follows:

[0165]

number

[0166] As shown in Figure 9, in design 2, the fundamental mode is achieved at a greater ratio of fiber space height to fiber core radius than in design 1. Regarding this point, the ratio of fiber space height FH_Z1 3800 to fiber core radius R_Faser2310 is as follows:

[0167]

number

[0168] In combination with this, in a modification of one embodiment, the first circular radius FA_R of 12.25 μm to 15.75 μm is, in particular, the ratio of the fiber space height FH_Z1 3800 to the fiber core radius R_Faser2310:

[0169]

number

[0170] Further positive effects of phase propagation velocity on coupling are particularly relevant for the first circle radius FA_R between 12.25 μm and 15.75 μm, regarding the ratio of fiber space height FH_Z1 to fiber core radius R_Faser, as follows: • FH_Z1 / R_Faser must be 0.8 or higher, 0.85 or higher, especially 0.9 or higher, especially 0.95 or higher, especially 1.0 or higher, and This can be achieved if FH_Z1 / R_Faser is 1.4 or less, especially 1.35 or less, especially 1.3 or less, especially 1.2 or less.

[0171] In Figure 10, the difference in waveguide loss between the fundamental mode and higher-order modes in the core (also called loss discrimination, LM, or waveguide loss difference) for two hollow core fiber designs is plotted against the ratio of the fiber spatial height FH_Z1 to the fiber core radius R_Faser. The waveguide loss difference is defined as follows: LM(FM vs HOM) = 10 * log 10 (HOM attenuation / FM attenuation).

[0172] In this context, the term attenuation specifically refers to the calculated waveguide loss for each mode, where, The results shown as dots are plotted for waveguide loss difference based on design 1. • The results indicated by the asterisk are plotted for the waveguide loss difference based on Design 2.

[0173] Curve fitting was used to fit curves with the shape of the resonance curve to both sets of results. High loss discrimination values ​​indicate a high difference in waveguide loss between the fundamental mode and higher-order modes, and are therefore desirable for the fundamental mode, which is achieved over short travel distances.

[0174] As shown in Figure 10, the hollow core fiber having design 1 has the following ratio of fiber space height FH_Z1 to fiber core radius R_Faser:

[0175]

number

[0176] As further shown in Figure 10, the hollow core fiber having design 2 has the following ratio of fiber space height FH_Z1 to fiber core radius R_Faser:

[0177]

number

[0178] In combination with this, a hollow core fiber having a first circular radius FA_R of 12.25 μm to 15.75 μm, in a modification of one embodiment, has the following ratio of fiber space height FH_Z1 to fiber core radius R_Faser:

[0179]

number

[0180] Simulations of anti-resonant hollow core fibers also surprisingly show that the geometric shape of the anti-resonant unit, particularly the ARU arc unit, affects the damping of the ARHCF, as shown in Figure 11.

[0181] In FIG. 11, for both designs, the confinement loss (also called waveguide loss or guiding loss) of the fundamental mode at a wavelength of 1,550 nm is plotted against the ratio of the fiber space height FH_Z1 3800 to twice the radius FB_R3920 of the ARU arc unit. · The results shown as dots are plotted for the waveguide loss difference based on Design 1. · The results shown as stars are plotted for the waveguide loss based on Design 2.

[0182] Curve fitting was used to fit curves to both sets of results.

[0183] As shown in FIG. 11, in Design 1, for the ratio of the fiber space height FH_Z1 3800 to twice the radius FB_R3920 of the ARU arc unit, the following

[0184]

Number

[0185] For the ratio of the fiber space height FH_Z1 3800 to twice the radius FB_R3920 of the ARU arc unit, the following

[0186]

Number

[0187] As shown in FIG. 11, in Design 2, for the ratio of the fiber space height FH_Z1 3800 to twice the radius FB_R3920 of the ARU arc unit, the following

[0188]

Number

[0189] Regarding the ratio of the fiber space height FH_Z1 3800 to twice the radius FB_R3920 of the ARU arc unit,

[0190]

number

[0191] In the modified embodiment shown in Figure 11, the ratio of the fiber space height FH_Z1 3800 to twice the radius FB_R3920 of the ARU arc unit is as follows:

[0192]

number

[0193] The ARU arc unit described in this embodiment is • The basic mode within the core hardly interacts with the DNE mode, but at the same time This is why higher-order modes within the core are effectively coupled with the more lossy arc unit modes.

[0194] This results in an ARHCF that enters the basic mode at short distances on the one hand, and on the other hand has only a low-attenuation basic mode.

[0195] A variation of another embodiment involves the following regarding the ratio of the fiber space height FH_Z1 3800 to twice the radius FB_R3920 of the ARU arc unit: FH_Z1 / (2*FB_R) is less than or equal to 1.2, especially less than or equal to 1.05, especially less than or equal to 1.0, especially less than or equal to 0.9, especially less than or equal to 0.85, and especially less than or equal to 0.8. The following conditions must be met: FH_Z1 / (2*FB_R) is 0.1 or greater, especially 0.125 or greater, especially 0.15 or greater, especially 0.2 or greater, especially 0.4 or greater, and especially 0.5 or greater.

[0196] Modifications of this embodiment are characterized by a positive effect on damping.

[0197] The anti-resonant hollow core fiber 1000 is characterized in that the deviation of the first circle radius FA_R3200 from the second circle radius FI_R3500 is less than 10% of the first circle radius FA_R3200. To determine the effect of these differences between the two circle radii on the fundamental modes, simulations were performed for two additional designs of the anti-resonant hollow core fiber 1000. Table 2 shows the different parameters for the simulated anti-resonant hollow core fiber 1000.

[0198] [Table 2]

[0199] All other parameters correspond to those listed in Table 1 and / or the parameters described in more detail above for the anti-resonant hollow core fiber 1000 according to Design 1. Thus, two simulations were performed in which only the second circle radius FI_R was varied by + / -10% relative to the first circle radius FA_R.

[0200] Figure 12 shows the results of this simulation. The effective mode refractive index difference Δneff(DNE) is plotted against the ratio of twice the radius of the ARU arc unit FB_R3920 to the fiber core radius R_Faser2310. • The results shown by the dots represent Δn based on Design 1. eff (DNE) is plotted (this is the same as shown in Figure 8), · The results shown as circles are plotted for Δn eff (DNE) based on Design 3, · The results shown as rectangles are plotted for Δn eff (DNE) based on Design 4.

[0201] Using curve fitting, the curve was fitted to the set of results for Design 1. [[ID=I2]]

[0202] The values calculated for Designs 3 and 4 are located directly on the curve fitted to the values for Design 1. At this point, the first circle radius FA_R3200 and the second circle radius FI_R3500 extend into the space for the design of ARHCF with low attenuation within a variation of 10% or less of the first circle radius FA_R3200.

Description of Signs

[0203] 1000 Anti-resonance hollow core fiber 2000 Clad or fiber clad 2150 Inside of the clad 2250 Inner radius of the clad 23I0 Fiber longitudinal axis 2310 Core radius R_Faser 2470 Hollow core 2980 First circle 2990 Second circle 3000 Anti-resonance unit (ARU) 3100 ARU outer unit of the anti-resonance hollow core fiber 3110 First body longitudinal axis 3150 ARU outer unit wall 3170 First internal space of the ARU outer unit 3200 First circle radius FA_R 3250 First central angle FA_MW 3280 First segment height 3290 First chord length 3400 ARU inner unit of the anti-resonance hollow core fiber 3410 Second longitudinal axis of the main body 3450 ARU Interior Unit Wall 3470 ARU Inner Unit Second Interior Space 3500 Second circle radius FI_R 3550 Second central angle FI_MW 3580 Second segment height F_Inenn 3590 Second chord length 3700, 3700' connecting seam 3730 Contact seam 3800 Fiber space height (FH_Z1) 3900 ARU arc unit 3910 First longitudinal axis of the main body 3920 ARU arc unit radius FB_R 3950 Circular wall Third internal space of the 3970 ARU arc unit 3980 ARU arc unit diameter FB_D

Claims

1. An anti-resonant hollow core fiber (1000), The longitudinal axis of the fiber (2300) and the fiber core radius R_Faser (2310), A fiber cladding (2000) including an inner bore (2200) of the cladding, Multiple anti-resonant units, Each includes an ARU outer unit (3100) and an ARU inner unit (3400), - The arc-shaped ARU outer unit (3100) and the arc-shaped ARU inner unit (3400) each comprise a plurality of anti-resonance units interconnected along two seam lines (3700, 3700') such that the ARU inner unit (3400) protrudes at least partially into the first internal space (3170) of the ARU outer unit (3100), The anti-resonance units (3000) are spaced apart from each other and arranged at desired positions inside the cladding (2150) so as not to come into contact with each other. - The ARU outer unit (3100) has a first circular radius FA_R (3200) and a first central angle FA_MW (3250), - The ARU inner unit (3400) has a second circular radius FI_R (3500) and a second central angle FI_MW (3550), The amount of deviation of the first circle radius FA_R(3200) from the second circle radius FI_R(3500) is less than 10% of the first circle radius FA_R(3200). - The first central angle FA_MW(3250) is less than 345° and greater than 275°. - The second central angle FI_MW(3550) is less than 195° and greater than 40°. In at least one anti-resonance unit (3000), - The ARU arc unit (3900) is placed in the first internal space (3170), - The ARU arc unit (3900) is circular, - It has a radius FB_R (3920), - The ARU arc unit (3900) is connected to the ARU inner unit (3400) along a contact seam (3730) in an anti-resonant hollow core fiber (1000), The ratio of twice the radius FB_R(3920) of the ARU arc unit to the fiber core radius R_Faser(2310) is as follows: [Math 1] An anti-resonant hollow core fiber (1000) characterized by the following:

2. The ratio of twice the radius FB_R(3920) of the ARU arc unit to the fiber core radius R_Faser(2310) is as follows: - 2*FB_R / R_Faser is 0.8 or higher, especially 0.9 or higher, especially 1.0 or higher, and - 2*FB_R / R_Faser must be 1.6 or less, especially 1.5 or less, especially 1.45 or less. The anti-resonant hollow core fiber (1000) according to claim 1, characterized in that the above applies.

3. The anti-resonance unit (3000) has a fiber space height FH_Z1 (3800), and the ratio of the fiber space height FH_Z1 (3800) to the fiber core radius R_Faser (2310) is as follows: [Math 2] The anti-resonant hollow core fiber (1000) according to claim 1 or 2, characterized in that the above applies.

4. The ratio of the fiber space height FH_Z1 (3800) to the fiber core radius R_Faser (2310) is as follows: - FH_Z1 / R_Faser is 0.8 or higher, 0.85 or higher, especially 0.9 or higher, especially 0.95 or higher, especially 1.0 or higher, and - FH_Z1 / R_Faser must be 1.4 or less, especially 1.35 or less, especially 1.3 or less, especially 1.2 or less. The anti-resonant hollow core fiber (1000) according to claim 3, characterized in that the above applies.

5. Regarding the ratio of the fiber space height FH_Z1 (3800) to twice the radius FB_R (3920) of the ARU arc unit, the following applies: [Math 3] An anti-resonant hollow core fiber (1000) according to any one of claims 1 to 4, characterized in that the above applies.

6. Regarding the ratio between the fiber space height FH_Z1 (3800) and twice the radius FB_R (3920) of the ARU arc unit, the following applies: - FH_Z1 / (2*FB_R) is 1.2 or less, especially 1.05 or less, especially 1.0 or less, especially 0.9 or less, especially 0.85 or less, especially 0.8 or less, and - FH_Z1 / (2*FB_R) must be 0.1 or greater, especially 0.125 or greater, especially 0.15 or greater, especially 0.2 or greater, especially 0.4 or greater, especially 0.5 or greater. The anti-resonant hollow core fiber (1000) according to claim 5, characterized in that the above applies.

7. The anti-resonant hollow core fiber (1000) according to any one of claims 1 to 6, characterized in that the amount of the deviation of the first circle radius FA_R from the second circle radius FI_R is less than 5%, particularly less than 3%, particularly less than 2%, and particularly less than 1% of the first circle radius FA_R.

8. The anti-resonant hollow core fiber (1000) according to any one of claims 1 to 7, characterized in that the anti-resonant hollow core fiber comprises three, four, five, six, seven, or eight anti-resonant units (3000).

9. At least one of the anti-resonance units (3000) has the following characteristics: - The ARU outer unit (3100) and / or the ARU inner unit (3400) and / or the ARU arc unit (3900) include an amorphous solid, in particular glass, in particular quartz glass. - The ARU outer unit (3100) and / or the ARU inner unit (3400) and / or the ARU arc unit (3900) are made of amorphous solid, in particular glass, in particular quartz glass. - The ARU outer unit (3100) and / or the ARU inner unit (3400) and / or the ARU arc unit (3900) are made of the same material, and in particular include or are composed of glass having a refractive index of at least 1.4, particularly 1.4 to 3, and particularly 1.4 to 2.8, and - The wall thicknesses of the ARU outer unit (3100), the ARU inner unit (3400), and the ARU arc unit (3900) are substantially the same. An anti-resonant hollow core fiber (1000) according to any one of claims 1 to 8, comprising at least one of the above.

10. The anti-resonant hollow core fiber (1000) has the following characteristics: - For transported wavelengths from 1.0 μm to 2.5 μm, the fundamental attenuation is less than 1.0 dB / km, especially less than 0.5 dB / km, especially less than 0.25 dB / km, especially less than 0.15 dB / km, and - For wavelengths transported up to 0.8 μm, the fundamental attenuation is less than 1 dB / km. An anti-resonant hollow core fiber (1000) according to any one of claims 1 to 9, characterized by comprising at least one of the above.

11. Regarding the first circle radius F_R(3200) and / or the second circle radius FI_R(3500), the following applies: - This is less than 30 μm, especially less than 20 μm, especially less than 17.5 μm, especially 16.5 μm or less, especially 15.75 μm or less, and / or This is larger than 5 μm, especially larger than 10 μm, especially 11.5 μm or larger, and especially 12.25 μm or larger. An anti-resonant hollow core fiber (1000) according to any one of claims 1 to 10, characterized in that the above applies.

12. At least one ARU arc unit (3900) has the following characteristics: - The radius FB_R(3920) of the ARU arc unit is less than 15 μm, particularly less than 12.5 μm, particularly less than 11 μm, and particularly less than 9.5 μm. - The radius FB_R(3920) of the ARU arc unit is greater than 0.75 μm, more particularly greater than 1 μm, and more particularly greater than 2.5 μm. An anti-resonant hollow core fiber (1000) according to any one of claims 1 to 11, characterized by comprising at least one of the above.

13. At least one of the anti-resonance units (3000) has the following characteristics: - The wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit is 0.1 μm to 2.5 μm, particularly 0.15 μm to 1.5 μm, particularly 0.25 μm to 0.75 μm, particularly 0.35 μm to 0.65 μm, and particularly 0.5 μm. With respect to the signal wavelength of 1550 nm in the first transmission window, the wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit is 0.35 μm to 0.65 μm, particularly 0.4 μm to 0.6 μm, particularly 0.5 μm. With respect to the 1550 nm signal wavelength in the second transmission window, the wall thickness of the ARU outer unit and / or the ARU inner unit and / or the ARU arc unit is 0.75 μm to 1.25 μm, particularly 0.9 μm to 1.1 μm, and particularly 1 μm. An anti-resonant hollow core fiber (1000) according to any one of claims 1 to 12, characterized by comprising at least one of the above.

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