Anti-resonant element preform for making Anti-resonant

Abstract

The invention relates to an anti-resonant element preform (100) for manufacturing an anti-resonant hollow-core optical fiber (600), comprising, in an axial top view, a circular first circular element (200) having a first circular radius (250) and an arc-shaped first arc element (300) having a first arc radius (350). The invention further relates to a method for producing an anti-resonant element preform, to a preform for producing an anti-resonant hollow-core optical fiber comprising at least one anti-resonant element preform, and to an anti-resonant hollow-core optical fiber. According to the invention, the first circular element (200) and the first arc element (300) are connected to each other at two contact points (400).

Description

[0001] This application is a divisional application of the invention patent application with the application date of November 12, 2021, application number 202180076585.3 and invention name “Anti-resonance element preform for manufacturing anti-resonance hollow core optical fiber”. Technical Field

[0002] The present invention relates to an antiresonance element preform for manufacturing an antiresonance hollow core optical fiber. The antiresonance element preform comprises a circular first circular element with a first circular radius and an arc-shaped first circular arc element with a first circular arc radius in an axial top view.

[0003] Furthermore, the present invention relates to a method for producing an antiresonance element preform, a preform for producing an antiresonance hollow-core optical fiber comprising at least one antiresonance element preform, and an antiresonance hollow-core optical fiber. Background Art

[0004] Conventional single-mode optical fibers made of solid material have a glass core region surrounded by a glass cladding region with a lower refractive index. Light guidance is thus based on total internal reflection between the core and cladding regions. However, the interaction of the guided light with the solid material is associated with increased delays during data transmission and a relatively low damage threshold (compared to high-energy radiation).

[0005] These drawbacks are avoided or minimized with "hollow-core fibers," in which the core consists of an evacuated cavity filled with a gas or liquid. Light in hollow-core fibers interacts less with the glass than in solid-core fibers. The refractive index of the core is lower than that of the cladding, making light guidance by total internal reflection impossible, and light typically escapes from the core into the cladding. Depending on the physical mechanism of light guidance, hollow-core fibers are classified as "photonic bandgap fibers" and "antiresonant hollow-core fibers."

[0006] In the case of a photonic bandgap fiber, a hollow core region is surrounded by a cladding in which small hollow tubes are periodically arranged. The periodic structure of the hollow tubes in the cladding induces an effect known in semiconductor technology as a photonic bandgap, whereby light of a specific wavelength range scattered by the cladding structure constructively interferes due to Bragg reflection in the central cavity and cannot propagate laterally in the cladding.

[0007] In the case of an embodiment of a hollow-core fiber known as an "antiresonant hollow-core fiber" (ARHCF), the hollow-core region is surrounded by an inner cladding region in which so-called "antiresonant elements" (or "antiresonant elements"; abbreviated as "AREs") are arranged. The walls of the antiresonant elements, uniformly distributed around the hollow core, can act as a Fabry-Perot cavity that operates with antiresonance, reflecting incident light and directing it through the fiber core.

[0008] This fiber optic technology guarantees low light attenuation, a very broad transmission spectrum (also in the UV or IR wavelength range) and small delays during data transmission.

[0009] Potential applications of hollow-core fibers are in the fields of data transmission, high-performance beam guiding (e.g. for materials processing), modal filtering, and nonlinear optics (particularly for supercontinuum generation, from the ultraviolet to the infrared wavelength range).

[0010] One disadvantage of antiresonant hollow-core fibers is that higher-order modes are not necessarily suppressed, so that they are usually not purely single-mode over large transmission lengths and the quality of the output beam is degraded.

[0011] In the paper "Nested antiresonant nodeless hollow core fiber" by Francesco Poletti, Optics Express, Vol. 22, No. 20 (2014); DOI: 10.1364 / OE 22.023807, a fiber design is proposed in which the antiresonant element is not formed as a simple single structural element, but rather consists of several nested structural elements. The nested antiresonant elements are designed in such a way that higher-order core modes, rather than the fundamental core mode, are phase-matched to the cladding mode and suppressed. The propagation of the fundamental core mode is thus always ensured, and the hollow-core fiber can be effectively rendered single-mode within a limited wavelength range.

[0012] The effective mode suppression depends on the central wavelength of the transmitted light and the structural parameters of the fiber design (such as the hollow core radius and the diameter difference of the nested ring structures in the antiresonant element).

[0013] EP 3136143 A1 discloses an antiresonant hollow-core fiber (referred to herein as a "gapless hollow-core fiber"), in which the core can guide additional modes in addition to the fundamental mode. For this purpose, the core is surrounded by an inner cladding comprising "non-resonant elements" that provide phase matching of the antiresonant mode with the higher-order modes. The hollow-core fiber is manufactured according to the so-called "build and draw" technique, in which the output elements are arranged to form an axially parallel monolith and fixed to form a preform, which is then elongated. A cladding tube with a hexagonal inner cross-section is used, and six so-called "ARE preforms" (antiresonant element preforms) are fixed in the inner edge of the cladding tube. This preform is stretched in two stages to form the hollow-core fiber.

[0014] WO 2015 / 185761 A1 discloses an antiresonant hollow-core fiber in which a further tubular, so-called “nested element” is arranged within a first tubular “non-resonant element”, which together form an antiresonant element.

[0015] One drawback in the manufacture of this component is the relatively large contact points created by the connection of the "nested" tubes within the first non-resonant element. Even slight deviations from the ideal structure negatively impact the optical fiber's light-guiding efficiency. Another drawback results from the limited variability in the design of the antiresonant element when only tubular elements are used.

[0016] CN 111 474 627 A discloses an antiresonant hollow-core fiber in which the antiresonant element is formed from circular and arcuate elements in an axial top view. The circular and arcuate elements are not connected to one another, but are instead directly connected to the fiber's cladding. This has the following disadvantages from a manufacturing perspective: The prefabrication of the antiresonant element preform that will form the antiresonant element in the final drawn fiber is not possible, but rather all structural elements must be directly connected to the cladding tube. This results in a high susceptibility to deviations from the ideal arrangement of the structural elements relative to one another, and thus a loss of efficiency during light guidance.

[0017] US 2020 / 0241200 A1 discloses an antiresonant hollow-core fiber, the antiresonant element of which, in an axial top view, comprises a circular element and a structural element shaped in a straight manner without bending. In the case of an antiresonant element, a disadvantage of the structural element shaped in a straight manner is that the light guidance is poorer than with a curved structural element and has a negative impact on the optical properties of the fiber (e.g., light attenuation). Summary of the Invention

[0018] The object of the present invention is to at least partially overcome one or several of the disadvantages arising from the prior art.

[0019] In particular, the present invention is based on the object of providing an antiresonant element preform from which an antiresonant hollow-core optical fiber with good optical properties, such as low optical attenuation, can be manufactured easily and in a reproducible manner.

[0020] A further object of the present invention is to provide a method by means of which antiresonance element preforms can be produced in a reproducible manner with high precision and good optical properties (eg low light attenuation).

[0021] Another object of the present invention is to specify a method for cost-effectively manufacturing a preform for an antiresonant hollow-core optical fiber, which avoids the limitations of conventional manufacturing methods.

[0022] Another object of the present invention is to provide a preform for fabricating an antiresonant hollow-core optical fiber that avoids the limitations of conventional preforms.

[0023] Another object of the present invention is to provide an antiresonant hollow core that avoids the limitations of conventional hollow core fibers.

[0024] The features of embodiment 1 contribute to at least partially satisfying at least one of the aforementioned objects. Embodiments 2 to 14 provide preferred embodiments that contribute to at least partially satisfying at least one of these objects.

[0025] / 1 / An anti-resonance element preform for manufacturing an anti-resonance hollow core optical fiber, the anti-resonance element preform comprising in an axial top view

[0026] a circular first circular element having a first circular radius and a circular arc shaped first circular arc element having a first circular arc radius,

[0027] It is characterized in that

[0028] The first circular element and the first circular arc element are connected to each other at two contact points.

[0029] / 2 / According to embodiment 1, an antiresonance element preform is characterized in that the first round element and the first arc element include glass, in particular quartz glass, in particular quartz glass with a refractive index of 1.4, in particular 1.4 to 3, in particular 1.4 to 2.8, or a polymer, and in particular consist of glass, in particular quartz glass, in particular quartz glass with a refractive index of at least 1.4, in particular 1.4 to 3, in particular 1.4 to 2.8, or a polymer.

[0030] / 3 / According to embodiment 1 or 2, an anti-resonance element preform is characterized in that the anti-resonance element preform includes a circular second circular element having a second circular radius.

[0031] / 4 / According to any one of the aforementioned embodiments, an anti-resonance element preform is characterized in that the anti-resonance element preform includes a second arc-shaped element with a second arc radius.

[0032] / 5 / According to any one of the preceding embodiments, an anti-resonance element preform is characterized in that the first circle radius has a smaller magnitude than the first arc radius.

[0033] / 6 / According to any one of the preceding embodiments, an anti-resonance element preform is characterized in that the first arc element is arranged within the first circular element.

[0034] / 7 / According to any one of embodiments 1 to 5, an anti-resonance element preform is characterized in that the first arc element is arranged outside the first circular element.

[0035] / 8 / A method for manufacturing an anti-resonance element preform according to any one of embodiments 1 to 7, comprising the following method steps:

[0036] (a) providing a first circular element having a first circular radius, the first circular element being circular in an axial top view;

[0037] (b) providing a first arc element having a first arc radius, the first arc element being arc-shaped in an axial top view;

[0038] (c1) arranging the first arc element within the first circular element so that the first arc end portion and the second arc end portion are arranged on the inner side of the first circular element;

[0039] or

[0040] (c2) arranging the first circular element outside the first circular element so that the first circular end portion and the second circular end portion are arranged on the outer side of the first circular element;

[0041] (d) connecting the first arc end portion and the second arc end portion to the first circular element by forming a second contact point.

[0042] / 9 / The method according to embodiment 8, characterized in that the connection in method step (d) is carried out by means of heat input.

[0043] / 10 / A preform for manufacturing an antiresonant hollow-core optical fiber, the preform comprising a cladding tube, characterized in that at least one antiresonant element preform according to any one of embodiments 1 to 7 is arranged in the cladding tube.

[0044] / 11 / Preform for manufacturing a reverse-harmonic hollow-core fiber according to embodiment 10, characterized in that the at least one reverse-harmonic element preform is connected to the inner surface of the cladding tube.

[0045] / 12 / Preform for manufacturing a reverse-harmonic hollow-core fiber according to embodiment 10 or 11, characterized in that 3 to 10 reverse-harmonic element preforms are arranged in the cladding tube.

[0046] / 13 / Reverse-harmonic hollow-core fiber comprising in an axial top view a cladding region and at least one reverse-harmonic element arranged in the cladding region, and a circular first circular structure having a first circular structure radius and a circular-arc-shaped first circular-arc structure having a first circular-arc structure radius,

[0047] characterized in that

[0048] the first circular structure and the first circular-arc structure are connected to each other at two contact points.

[0049] / 14 / Reverse-harmonic hollow-core fiber according to embodiment 13, manufactured by drawing a preform according to any one of embodiments 10 to 12.

[0050] General

[0051] The range specifications in this specification also include the values mentioned as limits. Thus, a specification of “in the range of X to Y” with respect to a type of variable A means that A can take the value X, the value Y, and values in between X and Y. Thus, a range of a type of variable A limited on one side “up to Y” thus means Y and values smaller than Y.

[0052] Some of the features described relate to the term “substantially”. The term “substantially” is to be understood in such a way that under practical conditions and manufacturing techniques a mathematically exact interpretation of terms such as “overlap”, “perpendicular”, “diameter”, or “parallelism” can never be exactly provided, but can only be applied within certain manufacturing-related error tolerances. For example, an “axis substantially perpendicular” draws an angle of 85 to 95 degrees to each other, and a “substantially equal volume” includes a deviation of at most 5% by volume. For example, a “device substantially consisting of quartz glass” includes a portion of > 95% by weight to < 100% by weight of quartz glass. For example, “substantially completely filling a volume B” includes filling a total volume B of > 95% by volume to < 100% by volume. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1shows an axial top view onto an anti-resonance element preform comprising a first circular element and a first circular arc element,

[0054] Figure 2 Another embodiment of an anti-resonance element preform is shown,

[0055] Figure 3 Another embodiment of an anti-resonance element preform is shown,

[0056] Figure 4 Another embodiment of an anti-resonance element preform is shown,

[0057] Figure 5 Another embodiment of an anti-resonance element preform is shown,

[0058] Figure 6 Another embodiment of an anti-resonance element preform is shown,

[0059] Figure 7 Another embodiment of an anti-resonance element preform is shown,

[0060] Figure 8 Another embodiment of an anti-resonance element preform is shown,

[0061] Figure 9 Another embodiment of an anti-resonance element preform is shown,

[0062] Figure 10 shows an axial top view onto the preform of an antiresonant hollow core fiber,

[0063] Figure 11 shows an axial top view onto the antiresonant hollow core fiber, and

[0064] Figure 12 A method for manufacturing an anti-resonance element preform is shown. DETAILED DESCRIPTION

[0065] The present invention relates to an antiresonance element preform for manufacturing an antiresonance hollow core optical fiber. The antiresonance element preform comprises a circular first circular element with a first circular radius and an arc-shaped first circular arc element with a first circular arc radius in an axial top view.

[0066] In order to overcome the above-mentioned disadvantages of the prior art, the present invention provides that the first circular element and the first arc element are connected to each other at two contact points, wherein the arc element is specifically connected to the circular element via a first arc end and via a second arc end opposite the first arc end. The first arc end and the second arc end are to be understood as the corner points of the first arc element that are visible on the anti-resonance element preform in an axial top view and between which the first arc element extends in an arc-shaped manner.

[0067] An antiresonance element preform constructed in this manner can be manufactured separately from other components used to manufacture an antiresonance hollow-core fiber, which is advantageous from a manufacturing perspective. Thus, an antiresonance element preform that deviates from its ideal structure (e.g., during its manufacture) can be processed in a relatively cost-effective manner without having to process additional components used to manufacture an antiresonance hollow-core fiber. Prefabrication of the antiresonance element preform additionally achieves uniformity across the entire manufacturing batch, which advantageously influences the symmetry of the preforms manufactured using the antiresonance element preform and, ultimately, also the symmetry of the antiresonance hollow-core fiber. The increased symmetry has a positive effect on the optical properties of the hollow-core fiber.

[0068] Furthermore, antiresonant elements fabricated from this type of antiresonant element preform have been shown to be components in the final hollow-core optical fiber with improved optical properties, which results in lower light propagation losses (i.e., including light scattering, diffraction, absorption, and inclusion) and, therefore, in a high data transmission capacity of the final hollow-core optical fiber.

[0069] It has become apparent that a circular arc element connected to a round element at two contact points allows a high degree of control over the structural parameters of the antiresonant element preform and thus makes it possible to provide an antiresonant hollow core optical fiber with improved optical properties.

[0070] The improved optical properties of this type of antiresonant hollow-core fiber are evident, for example, in an optical attenuation of less than 0.15 dB / km at wavelengths between 1.0 μm and 2.5 μm, or less than 1 dB / km at wavelengths up to 0.8 μm. Any phenomenon that results in a reduction in the intensity of a propagating signal without thereby affecting its shape is referred to as optical attenuation.

[0071] The component or component portion is referred to as an antiresonant element preform, which essentially becomes the antiresonant element in the hollow-core optical fiber by means of simple length molding (also called elongation) during the fiber drawing process.

[0072] In an axial top view (i.e., a two-dimensional view along the longitudinal axis), the antiresonance element preform comprises a first circular element, which corresponds to the tubular structural element in a three-dimensional view. The first circular element has a substantially uniform first circular radius and is therefore designed to be substantially circular, wherein the radius at a first point deviates from the radius at another point by no more than 5%, preferably no more than 3%, more preferably no more than 1%, and most preferably no more than 0.5%. Thus, the first circular element has a substantially uniform diameter, wherein the diameter at the first point deviates from the diameter at another point of the antiresonance element preform by no more than 5%, preferably no more than 3%, more preferably no more than 1%, and most preferably no more than 0.5%. For example, the first circular radius can thus be in the range of 2 mm to 18 mm, preferably in the range of 3 mm to 16 mm, and more preferably in the range of 4 mm to 12 mm. The first circular element has a wall thickness in the range of 0.1 mm to 3 mm, preferably 0.1 mm to 2 mm, and more preferably 0.2 mm to 1.5 mm.

[0073] In an axial top view, i.e., a two-dimensional view onto the longitudinal axis, the antiresonance element preform comprises a first arc element, which, in a three-dimensional view, corresponds to a segment of a tubular, substantially circular structural element, cut out parallel to the longitudinal axis, or in other words, parallel to the curved disk. The first arc element has a substantially uniform first arc. Thus, in a three-dimensional view, the first arc element represents a segment of a substantially circular tubular structural element (cut out parallel to the longitudinal axis) having a radius corresponding to the arc radius, wherein the radius at a first point deviates from the radius at another point by no more than 5%, preferably no more than 3%, more preferably no more than 1%, and most preferably no more than 0.5%. For example, the first arc radius can thus be in the range of 1 mm to 30 mm, preferably in the range of 2 mm to 25 mm, and more preferably in the range of 3 mm to 20 mm. The first arc element has a wall thickness in the range of 0.1 mm to 3 mm, preferably 0.1 mm to 2 mm, and more preferably 0.2 mm to 1.5 mm.

[0074] The circle radius and arc radius are to be understood in each case as the outer radius of the corresponding element. The corresponding inner radius is obtained by subtracting the corresponding wall thickness from the corresponding outer radius. The same applies to the corresponding diameter.

[0075] The contact points are locations where the first circular element and the first circular arc element are connected to each other, specifically by means of a material-to-material bond. In one embodiment, the first circular arc element is connected to the first circular element via a first circular arc end and a second circular arc end opposite the first circular arc end. The first circular element and the first circular arc element are connected to each other at exactly two contact points.

[0076] The contact points can be designed differently. In one embodiment, the first circular element and the first circular arc element are connected to each other at the least one contact point via fastening means such as, for example, adhesive, rivets, screws or nails. In a preferred design, the first circular element and the first circular arc element are connected to each other at least at one contact point, preferably at two contact points, by means of substance-to-substance bonding.

[0077] In order to provide a counter-resonator element preform with high structural precision and improved optical properties, the first circular arc element comprises a circular arc element circumference corresponding to 10% to 85%, preferably 20% to 80%, more preferably 20% to 75%, even more preferably 20% to 70% of the circumference of a complete circular element, which corresponds to the first circular arc radius. The advantage thereby is that the contact points are positioned spatially at such a distance from each other that the first circular arc element and the first circular arc are connected to each other without the contact points merging into each other and that there is one large contact point instead of two disjoint contact points. A large contact point would have a negative influence on the optical light guiding properties of the final glass optical fiber, for example by a local increase of the material portion, for example glass, at the large contact point, which can lead to ovality of the counter-resonator element.

[0078] At the contact points, the first circular element and the first circular arc element in each case draw an external angle of greater than 10°, preferably greater than 15°, more preferably greater than 20°, most preferably greater than 25°. The external angle is thereby not greater than 160°, preferably not greater than 150°, more preferably not greater than 130°. The external angle is to be understood as the angle drawn in the axial top view at the contact point between the convex side of the first circular element and the first circular arc element. This allows to provide a counter-resonator element preform with high structural precision and improved optical properties.

[0079] In one embodiment, the entire counter-resonator element preform comprises or consists of a material which is transparent for the working light of the optical fiber, for example glass, in particular doped or undoped quartz glass (Si02). Doping makes it possible to adapt physical properties, for example the coefficient of thermal expansion. Fluorine, chlorine and / or hydroxyl groups are preferably used as dopants, which reduce the viscosity of the quartz glass.

[0080] An embodiment of the antiresonance element preform is characterized in that the first circular element and the first arcuate element comprise at least glass (in particular, doped or undoped quartz glass, in particular, quartz glass with a refractive index of at least 1.4, in particular, 1.4 to 3), or a polymer (for example, polymethyl methacrylate, cyclic olefin copolymer, polycarbonate, or fluoropolymer). In another embodiment, the first circular element and the first arcuate element consist of glass (in particular, doped or undoped quartz glass, in particular, quartz glass with a refractive index of at least 1.4, in particular, 1.4 to 3), or a polymer (for example, polymethyl methacrylate, cyclic olefin copolymer, polycarbonate, or fluoropolymer).

[0081] In one embodiment, the first circular element and the arcuate element are made of the same material. In another embodiment, the first circular element and the first arcuate element are made of the same material, specifically undoped or doped quartz glass, in particular glass with a refractive index of at least 1.4, specifically 1.4 to 3, in particular 1.4 to 2.8, wherein the doping amount does not exceed 0.1% by weight.

[0082] The term "same material" describes the material properties of the two components. The two components thus have essentially the same chemical composition. The total mass of the different chemical elements in the two components can thus be less than 1% by weight, in particular less than 0.5% by weight, and especially less than 0.1% by weight. The chemical compositions of the two components may differ in particular by a contaminant content of less than 500 ppm by weight, in particular less than 100 ppm by weight, and / or a dopant content of less than 10,000 ppm by weight, in particular less than 5,000 ppm by weight.

[0083] In one embodiment, the anti-resonance element preform is composed of a first circular element and a first circular arc element.

[0084] An embodiment of the anti-resonance element preform is characterized in that the anti-resonance element preform comprises a circular second circle element having a second circle radius.

[0085] The second circular element may have the same features and characteristics as the first circular element described above, wherein the second circular radius may be designed to be greater than, less than, or equal to the first circular radius.

[0086] In one embodiment, the second circular element is arranged inside the first circular element. In one embodiment, the first circular element and the second circular element are connected to each other at the contact point, in particular by means of a material-to-material bond. In another embodiment, the first circular element and the second circular element are connected to each other, in particular by means of a material-to-material bond. In another embodiment, the second circular element is connected to the first circular element and to the first circular element, in particular by means of a material-to-material bond.

[0087] In another embodiment, the first round element is arranged within the second round element, wherein the first round element and the second round element are preferably connected to each other at the contact points, in particular by means of substance-to-substance bonding.

[0088] In another embodiment, the second circular element is arranged in a space surrounded by the first circular element and the first arc element, wherein the second circular element is specifically connected to the first circular element, to the first arc element, or to the first circular element and the first arc element by means of material-to-material bonding.

[0089] An embodiment of the anti-resonance element preform is characterized in that the anti-resonance element preform comprises a second arc-shaped element having a second arc radius.

[0090] The second arc element may have the same features and characteristics as the first arc element described above, wherein the second arc radius may be greater than, less than, or equal to the first arc radius.

[0091] In one embodiment, the second circular arc element is arranged within the first circular element, wherein the first circular element and the second circular arc element are preferably connected to each other at two contact points, in particular by means of substance-to-substance bonding.

[0092] In another embodiment, the second circular element is arranged in a space enclosed by the first circular element and the first circular element, wherein the second circular element is connected to the first circular element at two contact points, to the first circular element at two contact points, or to the first circular element at one contact point and to the first circular element at one contact point, specifically by means of material-to-material bonding.

[0093] Due to the fact that the anti-resonance element preform has the first circular element and the first circular arc element as structural elements, the degree of freedom in selecting the first circular radius and the first circular arc radius is greater than when the anti-resonance element preform is formed using only circular elements as structural elements.

[0094] In one embodiment, the first circle radius and the first arc radius have substantially the same value.When only round elements are used to form the anti-resonance element preform, the corresponding structural units will be inaccessible.

[0095] In another design, the first circle radius has a larger value than the first arc radius.

[0096] An embodiment of the anti-resonance element preform is characterized in that the first circle radius has a smaller value than the first circle arc radius.When only round elements are used to form the anti-resonance element preform, the corresponding structural units would be inaccessible.

[0097] The first circle element and the first arc element may be arranged differently relative to each other, as long as the two elements are connected to each other, in particular by means of substance-to-substance bonding, at a minimum of two, preferably exactly two, contact points.

[0098] An embodiment of the antiresonance element preform is characterized in that the first circular arc element is arranged inside the first circular element. This means that the first circular arc element is connected to the inner side of the first circular element at two contact points, specifically by means of material-to-material bonding. The first circular arc element is thus arranged on the inner side of the first circular element. This allows for providing a circular or (in a three-dimensional view) tubular antiresonance element preform with improved optical properties, so that it can be easily handled. Such an antiresonance element preform can be easily and with high structural precision connected to other components of the preform in order to manufacture an antiresonance hollow-core optical fiber.

[0099] An embodiment of the anti-resonance element preform is characterized in that the first circular arc element is arranged outside the first circular element. This means that the first circular arc element is connected to the outer side of the first circular element at two contact points, specifically by means of material-to-material bonding. The first circular arc element is thus arranged on the outer side of the first circular element. This allows the production of an anti-resonance element preform having an 8-shaped profile in an axial top view, or an irregular 8-shaped profile depending on the respective radii of the first circular element and the first circular arc element.

[0100] Furthermore, the present invention relates to a method for producing the above-mentioned anti-resonance element preform.

[0101] Depending on the desired design of the anti-resonance element preform, the method can be performed in different ways.

[0102] A first embodiment of a method for producing an anti-resonance element preform according to any of the above designs comprises at least the following method steps:

[0103] (a) providing a first circular element having a first circular radius, the first circular element being circular in an axial top view;

[0104] (b) providing a first arc element having a first arc radius, the first arc element being arc-shaped in an axial top view;

[0105] (c1) arranging the first arc element (300) inside the first circular element (200) so that the first arc end (305) and the second arc end (306) are arranged on the inner side (205) of the first circular element (200);

[0106] (d) connecting by forming a second contact point (particularly connecting by material-to-material bonding)

[0107] The first arc end and the second arc end.

[0108] The first embodiment of the method for producing a preform of a counter- resonant element is used to produce the above-mentioned preform of a counter- resonant element, in the case of which a first arc element is arranged inside a first circular element. The first embodiment of the method can be used to produce a substantially circular preform of a counter-resonant element.

[0109] The second embodiment of the method for producing a preform of a counter- resonant element according to any of the above designs comprises at least the following method steps:

[0110] (a) providing a first circular element having a first circular radius, which is circular in an axial top view;

[0111] (b) providing a first arc element having a first arc radius, which is circular-arc-shaped in an axial top view;

[0112] (c2) arranging the first arc element outside the first circular element, so that a first arc end and a second arc end are arranged on the outside of the first circular element;

[0113] (d) connecting, in particular by substance-to-substance bonding, the first arc end and the second arc end by forming a second contact point.

[0114] The second embodiment of the method for producing a preform of a counter- resonant element is used to produce the above-mentioned preform of a counter- resonant element, in the case of which a first arc element is arranged outside a first circular element. The second embodiment of the method can be used to produce a counter- resonant element whose contour is in the shape of an 8 in an axial top view, or an irregular 8 depending on the corresponding radii of the first circular element and the first arc element.

[0115] The connection in method step (d) can be carried out differently in all embodiments of the method, for example via adhesion, screw connection, riveting, welding, stapling or clamping.

[0116] The embodiment of the method for producing the above-mentioned preform of a counter-resonant element is characterized in that the connection in method step (d) is carried out by means of a heat input.

[0117] The heat input is in particular used for substance-to-substance bonding of the first circular element and the first arc element at the contact point. The heat input must be carried out in such a way that substance-to-substance bonding between the materials of the two elements is possible. This can be achieved in such a way that at least at the contact point, the surface of the elements at least partially changes from a solid state to a liquid state, in particular a viscous state.

[0118] Heat input can be achieved in different ways, for example by means of:

[0119] - Flame-based processes: based on the oxidation of exothermic reaction gases. An example is the use of hydrogen (also called "H2") as the exothermic reaction combustion gas (flame hydrolysis). It reacts with oxygen (also called "O2") in the air; or

[0120] - Flameless processes: Other systems that use heating and do not require an open flame. An example is the use of resistors that can convert electrical energy into thermal energy (heat).

[0121] Furthermore, the present invention relates to a preform for producing an antiresonant hollow-core optical fiber, the preform comprising a cladding tube, characterized in that at least one antiresonant element preform as described above is arranged in the cladding tube.

[0122] The preform is a component from which an antiresonant hollow-core fiber can be drawn. Alternatively, the preform can be further processed into a secondary preform, from which an antiresonant hollow-core fiber is drawn. This further processing can include one or repeated executions of a thermoforming process, such as, for example, stretching, collapsing, or adding additional cladding material.

[0123] The cladding tube is a tubular element made essentially of quartz glass, within which at least one antiresonant element preform described above is disposed. When the final preform is drawn into the final optical fiber, the cladding tube surrounds the hollow core of the antiresonant hollow-core fiber. In one embodiment, the cladding tube has an inner diameter in the range of 10 mm to 60 mm. In one embodiment, the cladding tube has an outer diameter in the range of 25 mm to 250 mm, preferably in the range of 30 mm to 200 mm. In one embodiment, the cladding tube has a length in the range of 500 mm to 1200 mm.

[0124] The at least one anti-resonance element preform may be arranged in different ways within the cladding tube.

[0125] Embodiments of the preforms are characterized in that at least one antiresonance element preform is connected to the inner surface of the cladding tube, in particular by means of a material-to-material bond. In one embodiment, the antiresonance element preform is connected to the cladding tube via a first circular element. In another embodiment, the antiresonance element preform is connected to the cladding tube via a first circular arc element, wherein in the case of these antiresonance elements, the first circular arc element is arranged outside the first circular element.

[0126] To construct the preform, different numbers of anti-resonance elements can be arranged within the cladding tube.

[0127] An embodiment of the preform is characterized in that 3 to 10, preferably 3 to 8, more preferably 4 to 6 anti-resonance element preforms are arranged in the cladding tube.

[0128] In one embodiment, only those anti-resonance element preforms having the properties and characteristics of the aforementioned anti-resonance element preforms are disposed within the cladding tube. In other designs, at least one anti-resonance element preform disposed within the cladding tube has other properties and characteristics that differ from the aforementioned anti-resonance element preforms.

[0129] Furthermore, the present invention relates to an antiresonant hollow-core optical fiber comprising, in an axial top view, a cladding region and at least one antiresonant element arranged in the cladding region, the antiresonant element comprising a circular first circular structure having a first circular structure radius and an arc-shaped first circular-arc structure having a first circular-arc structure radius, characterized in that the first circular structure and the first circular-arc structure are connected to each other at two contact points.

[0130] An antiresonant hollow-core fiber can be manufactured from the preform described above, specifically by stretching the preform, wherein at least a portion of the cladding region of the antiresonant hollow-core fiber is formed by the cladding tube of the preform, and at least one antiresonant element of the antiresonant hollow-core fiber is formed by at least one antiresonant element preform of the preform. Thus, the first circular structure is constructed from the first circular element, and the first circular arc structure is constructed from the first circular arc element. Corresponding contact points are maintained.

[0131] The preform is stretched during the elongation. The elongation is preferably performed proportionally so that, for example, the shape and arrangement of components or component parts of the preform, in particular the first circular element and the first circular arc element, are reflected in the elongated final product.

[0132] In an embodiment of an antiresonant hollow-core fiber, the cladding region corresponds to an elongated cladding tube. In another design, the cladding region corresponds to a cladding tube and a cover tube that is added to the cladding tube before or during elongation. "Added" is understood to mean connecting the cladding tube and the cover tube by material-to-material bonding, particularly with the aid of heat input and preferably by using negative pressure applied between the cladding tube and the cover tube.

[0133] To draw and produce an antiresonant hollow-core fiber from a preform, the preform can be guided vertically through a furnace. The lower end of the preform is thereby heated to the drawing temperature, from which the antiresonant hollow-core fiber is drawn in a tapered form, the drawn fiber subsequently being cooled from the drawing temperature by means of a gas flow directed opposite to the drawing direction.

[0134] The properties and features disclosed in the specification may be important for various embodiments of the claimed invention (individually and in any combination with each other). Properties and features disclosed for the antiresonant element preform, preform or antiresonant hollow core fiber are also disclosed for the method, and vice versa.

[0135] The present invention will be further described below in an exemplary manner with the aid of the accompanying drawings. The present invention is not limited to the accompanying drawings.

[0136] Figure 1 An antiresonance element preform 100 is shown in an axial top view. The antiresonance element preform 100 includes a circular first circular element 200 having a first circular radius 250. A first circular arc element 300 having a first circular arc radius 350 is arranged within the first circular element 200. In the illustrated embodiment of the antiresonance element preform 100, the first circular radius 250 and the first circular arc radius 350 have the same value. The first circular element 200 and the first circular arc element 300 are connected to each other at two contact points 400, specifically by means of a material-to-material bond. At the contact points 400, the convex side of the first circular arc element 300 and the inner side of the first circular arc each define an outer angle 150, which has the same value due to the symmetrical arrangement of the antiresonance element preform 100 in the illustrated embodiment. In other, not illustrated, embodiments, the two outer angles 150 are different. In the illustrated embodiment, the first circular element 200 and the first circular arc element 300 are formed from the same material, specifically doped or undoped quartz glass.

[0137] Figure 2 Another embodiment of an anti-resonance element preform 100a is shown. Figure 2 The embodiments correspond largely to those described above and in Figure 1 The embodiment shown in FIG. 1 is such that reference is made to the above description to avoid repetitions. Figure 1 Repeated structures in the description have the same reference numerals. Figure 1 Modifications of the structure compared to the illustrated structure have the same reference numerals with an additional letter a.

[0138] In the embodiment shown, the first circle radius 250 has a larger value than the first arc radius 350a, so that the outer angle 150a is larger than the first arc radius 350a. Figure 1 The outer angle is 150. Figure 1 Compared with the smaller first arc radius 350a, Figure 1 Contact points 400a are also positioned closer together than contact points 400a.

[0139] Figure 3 Another embodiment of an anti-resonance element preform 100b is shown. Figure 3 The embodiments of the invention correspond largely to the embodiments described above and shown in the above figures, so that reference is made to the above description to avoid repetitions. Structures repeated from the description of the above figures have the same reference numerals. Modifications of structures compared to the structures shown in the above figures have the same reference numerals with the additional letter b. Figure 2 Compared to embodiment 100a in FIG. 1 , another embodiment 100b of the anti-resonance element preform has a circular arc-shaped second arc element 310 with a second arc radius 360. Like the first arc element 300a, the second arc element 310 is arranged within the first circular element 200 and connected to the first circular element 200 at two contact points 330. In the illustrated embodiment, the first arc radius 350a and the second arc radius 360 have the same value. In another, not illustrated, embodiment, the first arc radius 350a and the second arc radius 360 may have different values. In the illustrated embodiment, the first arc element 300a and the second arc element 360 are arranged on opposite inner sides of the first circular element 200, such that the corresponding convex sides of the first arc element 300a and the second arc element 310 face each other. In another, not illustrated, embodiment, the first arc element 300a and the second arc element 310 are arranged closer together spatially on the inner side of the first circular element 200.

[0140] Figure 4 Another embodiment of an anti-resonance element preform 100c is shown. Figure 4 The embodiments of the present invention correspond largely to those described above and shown in the above figures, so that reference is made to the above description to avoid repetitions. Structures repeated from the description of the above figures have the same reference numerals. Modifications of structures compared to the structures shown in the above figures have the same reference numerals with the additional letter c.

[0141] In the illustrated embodiment, the second arc element 310c is arranged within the first circular element 200 on the same side as the first arc element 300, wherein the first arc radius 350 and the second arc element 360c have the same value. The first arc element 350 and the second arc element 310c are arranged relative to each other in such a manner that the convex side of the second arc element 310c faces the concave side of the first arc element 300. In another, not illustrated, embodiment, the first arc element 350 and the second arc element 310c are arranged relative to each other in such a manner that the concave side of the second arc element 310c faces the concave side of the first arc element 350.

[0142] Figure 5 Another embodiment of an anti-resonance element preform 100d is shown. Figure 5The embodiments of the present invention correspond largely to those described above and shown in the above figures, so that reference is made to the above description to avoid repetition. Structures repeated from the description of the above figures have the same reference numerals. Modifications of structures compared to the structures shown in the above figures have the same reference numerals with the additional letter d.

[0143] In the illustrated embodiment of the anti-resonance element preform 100d, the second circular arc element 310d is arranged within the first circular element 200 on the same side as the first circular arc element 300. Figure 4 , wherein the first arc radius 350 has a smaller value than the second arc radius 360d. The first arc element 300 and the second arc element 360 are arranged at the same point on the first circular element 200 so that the contact point 400 of the first arc element 400 and the contact point 330d of the second arc element 330 coincide with the first circular arc 200. The first arc element 350 and the second arc element 310d are arranged relative to each other in such a manner that the convex side of the second arc element 310d faces the concave side of the first arc element 300. In another embodiment not shown, the first arc element 350 and the second arc element 310d are arranged relative to each other in such a manner that the concave side of the second arc element 310d faces the concave side of the first arc element 350.

[0144] Figure 6 Another embodiment of an anti-resonance element preform 100e is shown. Figure 6 The embodiments of the present invention correspond largely to those described above and shown in the above figures, so that reference is made to the above description to avoid repetition. Structures repeated from the description of the above figures have the same reference numerals. Modifications of structures compared to the structures shown in the above figures have the same reference numerals with the additional letter "e".

[0145] The illustrated embodiment of the anti-resonance element preform 100e has a second circular element 210 with a second circular radius 260. The second circular element 210 is arranged in a space formed by the inner side of the first circular element 200 and the concave side of the first circular arc element 300. Thus, the second circular element 210 is connected to the first circular element 200. In another, not shown, embodiment, the second circular element 210 is connected to the first circular arc element 300 or to both the first circular element 200 and the first circular arc element 300. In another, not shown, embodiment, the second circular element 210 is arranged in a space formed by the inner side of the first circular element 200 and the convex side of the first circular arc element 300, wherein the second circular element 210 is connected to the first circular arc element 300 and / or the first circular element 200.

[0146] Figure 7Another embodiment of an anti-resonance element preform 100f is shown. Figure 7 The embodiments of the present invention correspond largely to those described above and shown in the above figures, so that reference is made to the above description to avoid repetitions. Structures repeated from the description of the above figures have the same reference numerals. Modifications of structures compared to the structures shown in the above figures have the same reference numerals with the additional letter f.

[0147] In the illustrated embodiment, the second circular element 210 is arranged in the space formed by the concave side of the second circular element 210d and the inner side of the first circular element 200. The second circular element 210 is thus connected to the first circular element 200. In another, not shown embodiment, the second circular element 210 is connected to the second circular element 210 or to the first circular element 200 and the second circular element 310d. In another, not shown embodiment, the second circular element 210 is arranged in the space formed by the convex side of the first circular element 300 and the inner side of the first circular element 200. In another embodiment, the second circular element 210 is arranged in the space formed by the first circular element 300 and the second circular element 310d, wherein the second circular element 210 is connected to the first circular element 300, the second circular element 310d, or the first circular element 300 and the second circular element 310d.

[0148] Figure 8 Another embodiment of an anti-resonance element preform 100g is shown. Figure 8 The embodiments of the present invention correspond largely to the embodiments described above and shown in the above figures, so that reference is made to the above description to avoid repetitions. Structures repeated from the description of the above figures have the same reference numerals. Modifications of structures compared to the structures shown in the above figures have the same reference numerals with the additional letter g.

[0149] The first circular arc element 300g is arranged outside the first circular element 200 and is connected to the first circular element at two contact points 400g, wherein the first circular element 200 and the first circular arc element 300g each have an outer angle 150g at the two contact points 400. The contour of the anti-resonance element preform 100g substantially corresponds to the contour of an 8. In the embodiment shown, the first circular arc radius 350g has a value greater than the first circular radius 250. In another embodiment not shown, the first circular arc radius 350g has a value equal to or less than the first circular radius 250.

[0150] Figure 9 Another embodiment of an anti-resonance element preform 100h is shown. Figure 9The embodiments of the present invention correspond largely to those described above and shown in the above figures, so that reference is made to the above description to avoid repetition. Structures repeated from the description of the above figures have the same reference numerals. Modifications of structures compared to the structures shown in the above figures have the same reference numerals with the letter h appended.

[0151] The illustrated embodiment has a first circular element 300g arranged outside the first circular element 200 and a second circular element 210h having a second circular element radius 260h arranged inside the first circular element 200, wherein the second circular element 210h and the first circular element 300g are arranged on opposite sides of the first circular element 200. In another, not illustrated, embodiment, the first circular element 300g and the second circular element 210h are arranged on the same side of the first circular element 200. In another, not illustrated, embodiment, the second circular element 210h is arranged in a space formed by the concave side of the first circular element 300g and the first circular element 200, wherein the second circular element 210g can be connected to the first circular element 200 and / or the first circular element 300g.

[0152] Figure 10 The preform 500 is shown, which includes a cladding tube 550 and a cladding tube 550 arranged in the cladding tube 550 according to Figure 1 In other, not shown, embodiments, the preform 500 comprises a different number (e.g., 2 to 10) of anti-resonance element preforms 100 and / or a preform according to the present invention (e.g., according to Figures 2 to 9 ) or the preform 500 includes an anti-resonance element preform according to the present invention (e.g., according to Figures 1 to 9 ) two or more different embodiments.

[0153] In the illustrated embodiment, four antiresonance element preforms 100 are attached to the inside of a cladding tube 550. The distribution of the antiresonance elements 100 on the inside of the cladding tube 500 is symmetrical, allowing a symmetrical antiresonance hollow-core fiber with improved optical properties to be fabricated from the preform 500 by elongating the preform 500. The four antiresonance element preforms 100 are arranged on the cladding tube 550 such that the convex sides of the corresponding first circular arc elements 300 are aligned in the direction of the center 510 of the preform 500. In other, not illustrated, embodiments, the concave sides of the first circular arc elements 300 may be aligned in the direction of the center 510, or multiple circular arc elements 300 may be aligned with corresponding convex sides in the direction of the center 510, and multiple first circular arc elements 300 may be aligned with corresponding concave sides. The arrangement of the circular arc elements 300 is preferably designed symmetrically with respect to the center 510.

[0154] Figure 11 It is shown that it is possible to, for example, extend the Figure 10 The antiresonant hollow core fiber 600 manufactured by the preform 500 includes a cladding region 550' and four antiresonant elements 100' arranged in the cladding region 550'. In another embodiment not shown, the antiresonant hollow core fiber 600 includes a different number (for example, 2 to 10) of antiresonant elements 100'. The antiresonant element 100' has a circular first circular structure 200' and an arc-shaped first circular arc structure 300'. The first circular arc structures 300' are each connected to the corresponding first circular structure 200' at two contact points 400'. In the embodiment shown, the antiresonant hollow core fiber 600 has a structure that can be stretched according to Figure 10 In another, not shown, embodiment, the antiresonant hollow-core fiber has a structure that can be obtained by means of a preform 500 according to the present invention (e.g. according to Figures 2 to 9 ) are elongated to obtain differently shaped antiresonance elements 100'. Four antiresonance elements 100' are arranged in the cladding region 550' such that the convex sides of corresponding first circular arc structures 300' are aligned in the direction of the hollow-core fiber center 610 of the antiresonant hollow-core fiber 600. In other, not-shown embodiments, the concave sides of the first circular arc structures 300' may be aligned in the direction of the hollow-core fiber center 610, or multiple circular arc structures 300' may be aligned with corresponding convex sides in the direction of the hollow-core fiber center 610, and multiple first circular arc structures 300' may be aligned with corresponding concave sides. The arrangement of the circular arc structures 300' is preferably designed symmetrically with respect to the hollow-core fiber center 610.

[0155] Figure 12 A method 700 is shown for making an anti-resonance element preform 100. In a first embodiment, the method 700 includes method steps 710, 720, 730, and 740. In a second embodiment, the method 700 includes method steps 710, 720, 740, and 750.

[0156] Method step 710 includes providing a first circular element 200 that is circular in axial top view, and method step 720 includes providing a first circular arc element 300 , 300 a , 300 g that is circular arc in axial top view.

[0157] The first circular element 200 and the first circular arc elements 300 , 300 a , 300 g may be arranged differently relative to each other.

[0158] In the first embodiment of the method 700, the first circular arc element 300, 300a and the first circular element 200 are arranged relative to each other in method step 730 in such a manner that the first circular arc element 300, 300a is arranged on the inner side of the first circular element 200 via a first circular arc end and via a second circular arc end opposite the first circular arc end. The first circular arc element 300, 300a is thus arranged within the first circular element 200.

[0159] In the second embodiment of the method 700, the first circular arc element 300g and the first circular element 200 are arranged relative to each other in method step 740 in such a way that the first circular arc element is arranged via the first circular arc end and via the second circular arc end on the outside of the first circular element 200. The first circular arc element 300g is thus arranged outside the first circular element 200.

[0160] In method step 750, the first and second arc ends, and thus the first arc elements 300, 300a, 300g, are connected to the first circular element 200. The connection in method step 750 can be achieved in different ways, for example, by adhesion, clamping or fastening means (for example, by screws, rivets or nails). In a preferred embodiment, the connection in method step 750 is performed by means of heat input.

[0161] The heat input is specifically used to connect the first circular element 200 and the first arc element 300, 300a, 300g by material-to-material bonding at the contact points 400, 400a, 400g of the two elements. The heat input is performed in such a way that material-to-material bonding between the materials of the two elements is possible. This can be achieved by at least partially changing the surface of the elements from a solid state to a liquid state (particularly a viscous state) at least at the contact points 400, 400a, 400g.

[0162] Heat input can be achieved in different ways, for example by means of:

[0163] - Flame-based processes: based on the oxidation of exothermic reaction gases. An example is the use of hydrogen (also called "H2") as the combustion gas (flame hydrolysis). Hereby the hydrogen reacts with oxygen (also called "O2") in the air; or

[0164] - Flameless processes: Other systems that use heating and do not require an open flame. An example is the use of resistors that can convert electrical energy into thermal energy (heat).

[0165] Figure Numbers

[0166] 100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h anti-resonance element preforms

[0167] 100' anti-resonance element

[0168] 150, 150a, 150g outer corner

[0169] 200 First circular element

[0170] 200' first circle structure

[0171] 210, 210h Second circular element

[0172] 250 First circle radius

[0173] 260, 260h Radius of the second circular element

[0174] 300, 300a, 300g first arc element

[0175] 300' first arc structure

[0176] 310, 310c, 310d second arc element

[0177] 330, 330c, 330d contact points of the first circular element and the second arc element

[0178] 350, 350a, 350g First arc radius

[0179] 360, 360c, 360d Second arc radius 400, 400a, 400g contact point between the first circular element and the first arc element

[0180] 400' Contact point between the first circular structure and the first arc structure

[0181] 500 preforms

[0182] 510 Center of preform

[0183] 550 cladding tube

[0184] 550' cladding area

[0185] 600 Antiresonant Hollow Core Fiber

[0186] 610 Center of Antiresonant Hollow-Core Fiber

[0187] 700 Methods

[0188] 710 Provide a first circular element

[0189] 720 provides the first arc element 730 Arrange the first arc element within the first circle element

[0190] 740 Arrange the first arc element outside the first circle element 750 connections

Claims

1. An antiresonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) for manufacturing an antiresonance hollow core optical fiber (600), the antiresonance element preform comprising, in an axial top view, a circular first circular element (200) having a first circular radius (250) and an arc-shaped first circular arc element (300, 300a, 300g) having a first circular arc radius (350, 350a, 350g), It is characterized in that The first circular element (200) and the first arc element (300, 300a, 300g) are connected to each other at two contact points (400, 400a, 400g); and The anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) includes a circular arc-shaped second arc element (310) having a second circular arc radius (360).

2. The anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to claim 1, characterized in that The first circular element (200) and the first arc element (300, 300a, 300g) include glass or polymer, or are composed of quartz glass or polymer.

3. The anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to claim 1 or 2, characterized in that: The anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) includes a circular second circular element (210) having a second circular radius (260).

4. The anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to claim 1 or 2, characterized in that: The first circle radius (250) has a smaller value than the first arc radius (350, 350a, 350g).

5. The anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to claim 1 or 2, characterized in that: The first arc element (300, 300a) is arranged inside the first circular element (200).

6. The anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to claim 1 or 2, characterized in that: The first arc element (300g) is arranged outside the first circular element (200).

7. The anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to claim 1, characterized in that: The first circular element (200) and the first arc element (300, 300a, 300g) include quartz glass or polymer, or consist of quartz glass or polymer.

8. A method (700) for producing an anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to any one of claims 1 to 7, the method comprising the following method steps: (a) providing (710) a first circular element (200), the first circular element being circular in an axial top view; (b) providing (720) a first arcuate element (300, 300a, 300g), the first arcuate element being arcuate in an axial top view; (c1) arranging (730) the first arc element (300, 300a) inside the first circular element (200) so that the first arc end and the second arc end are arranged on the inner side of the first circular element (200); or (c2) arranging (740) the first circular element (300g) outside the first circular element (200) so that the first circular end portion and the second circular end portion are arranged on the outer side of the first circular element (200); (d) connecting (750) the first arc end portion and the second arc end portion to the first circular element (200) by forming a second contact point (400, 400a, 400g).

9. The method (700) according to claim 8, characterized in that The connection ( 750 ) in method step (d) is performed by means of heat input.

10. A preform (500) for manufacturing an antiresonant hollow core optical fiber (600), the preform comprising a cladding tube (550), characterized in that: At least one anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to any one of claims 1 to 7 is arranged in the cladding tube (550).

11. The preform (500) for manufacturing an antiresonant hollow core optical fiber (600) according to claim 10, characterized in that: The at least one anti-resonance element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) is connected to the inner surface of the cladding tube (550).

12. The preform (500) for manufacturing an antiresonant hollow core optical fiber according to claim 10 or 11, characterized in that: 3 to 10 anti-resonance element preforms (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) are arranged in the cladding tube (550).

13. An antiresonant hollow-core optical fiber (600), comprising, in an axial top view, a cladding region (550') and at least one antiresonant element (100') arranged in the cladding region (550'), the antiresonant element comprising a circular first circular structure (200') having a first circular structure radius and an arc-shaped first circular arc structure (300') having a first circular arc structure radius, It is characterized in that The first circular structure (200') and the first arc structure (300') are connected to each other at two contact points (400'), and the antiresonant hollow-core optical fiber is manufactured by drawing the preform (500) according to any one of claims 10 to 12.

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