Anti-resonant element preform for manufacturing an anti-resonant hollow fiber

Abstract

The present invention relates to an anti-resonant element preform (100) for manufacturing an anti-resonant hollow fiber (600). The anti-resonant element preform includes, in an axial top view, a circular first circular element (200) having a first circular radius (250) and an arcuate first arcuate element (300) having a first arc radius (350). Furthermore, the present invention relates to a method for manufacturing an anti-resonant element preform, a preform for manufacturing an anti-resonant hollow fiber including at least one anti-resonant element preform, and an anti-resonant hollow fiber. According to the present invention, it is provided that the first circular element (200) and the first arcuate element (300) are connected to each other at two contact points (400).

Description

[0001] Description

[0002] The present invention relates to an anti-resonant element preform for manufacturing an anti-resonant hollow fiber, which in an axial top view includes a circular first circular element having a first circular radius and an arcuate first arc element having a first arc radius.

[0003] Furthermore, the present invention relates to a method for manufacturing an anti-resonant element preform, a preform for manufacturing an anti-resonant hollow fiber including at least one anti-resonant element preform, and an anti-resonant hollow fiber. Background Art

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

[0005] "Hollow fibers" avoid or reduce these disadvantages, in which case the core includes a evacuated cavity filled with a gas or a liquid. The interaction of light in a hollow fiber with the glass is less than the interaction of light in a solid-core fiber with the glass. The refractive index of the core is less than the refractive index of the cladding, such that light guiding by means of total reflection is not possible, and light will generally escape from the core into the cladding. Depending on the physical mechanism of light guiding, hollow fibers are divided into "photonic bandgap fibers" and "anti-resonant hollow fibers".

[0006] In the case of "photonic bandgap fibers", the hollow region is surrounded by a cladding in which small hollow ducts are periodically arranged. The periodic structure of the hollow ducts in the cladding causes an effect known in semiconductor technology as a "photonic bandgap", according to which light in a specific wavelength range scattered at the cladding structure undergoes constructive interference 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 fiber called an "anti-resonant hollow fiber" (ARHCF), the hollow region is surrounded by an inner cladding region in which so-called "anti-resonant elements" (or "anti-resonant elements"; abbreviated as "ARE") are arranged. The walls of the anti-resonant elements uniformly distributed around the hollow can act as Fabry-Perot cavities, which operate in anti-resonance, reflect the incident light, and guide the incident light through the fiber core.

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

[0009] Potential applications of hollow-core optical fibers are in the following fields: data transmission, high-performance beam guiding (e.g., for material processing), modal filtering, non-linear optical devices (especially for supercontinuum generation, in the wavelength range from ultraviolet to infrared).

[0010] Prior art

[0011] One disadvantage of anti-resonant hollow-core optical fibers is that higher-order modes are not necessarily suppressed, such that they are generally not purely single-mode over large transmission lengths and the quality of the output beam deteriorates.

[0012] In the paper "Nested anti-resonant nodeless hollow core fiber" by Francesco Poletti; Optics Letters, Vol. 22, No. 20 (2014); DOI: 10.1364 / OE 22.023807, an optical fiber design is proposed in which the anti-resonant elements are not formed as simple single structural elements, but rather consist of several nested structural elements. The nested anti-resonant elements are designed in such a way that higher-order core modes, rather than the fundamental core mode, are phase-matched to the cladding modes and suppressed. Thus, propagation of the fundamental core mode is always ensured and the hollow-core optical fiber can be effectively made single-mode in a limited wavelength range.

[0013] Effective mode suppression depends on the central wavelength of the transmitted light and the structural parameters of the optical fiber design (such as the hollow-core radius and the diameter difference of the nested ring structure in the anti-resonant elements).

[0014] An anti-resonant hollow-core optical fiber (referred to herein as "hollow-core optical fiber without a bandgap") is known from EP 3136143 A1, in which case, in addition to the fundamental mode, the core can also guide additional modes. For this purpose, the core is surrounded by an inner cladding including a "non-resonant element" which provides phase matching of the anti-resonant modes to the higher-order modes. The manufacturing of the hollow-core optical fiber is carried out according to the so-called "stacking and drawing" technique, in which the output elements are arranged to form an axially parallel assembly and are fixed to construct a preform, which is then elongated. Thereby, a cladding tube with a hexagonal inner cross-section is used and six so-called "ARE preforms" (anti-resonant element preforms) are fixed in the inner edge of the cladding tube. The preform is stretched in two stages to form the hollow-core optical fiber.

[0015] An anti-resonant hollow-core optical fiber is known from WO 2015 / 185761 A1, in which case, within a first tubular "non-resonant element", additional tubular, so-called "nested elements" are arranged, which together form the anti-resonant element.

[0016] One disadvantage in the manufacture of this component is the relatively large contact points, which are created by the connection of the "nested" tubes within the first non-resonant element and which, with a slight deviation from the ideal structure, already lead to a negative impact on the light guiding efficiency of the optical fiber. When only using tubular elements, another disadvantage results in a small range of variation in the design of the anti-resonant element.

[0017] An anti-resonant hollow optical fiber is known from CN 111 474 627A, in which the anti-resonant element is formed by a circular element and an arc element in an axial top view. The circular element and the arc element are not connected to each other, but are each directly connected to the cladding of the optical fiber. From a manufacturing perspective, this has the following disadvantages: It is not possible to pre-fabricate the anti-resonant element preform that forms the anti-resonant element in the final drawn optical fiber, but rather all structural elements must be directly connected to the cladding tube. This ensures a high susceptibility to deviations regarding the ideal arrangement of the structural elements relative to each other and thus ensures an efficiency loss during light guiding.

[0018] An anti-resonant hollow optical fiber is known from US 2020 / 0241200 A1, the anti-resonant element of which includes a circular element and a structural element formed in a straight manner without bends in an axial top view. In the case of the anti-resonant element, the disadvantage of the structural element formed in a straight manner is the light guiding, which is poorer compared to a bent structural element and has a negative impact on the optical properties of the optical fiber (such as light attenuation).

[0019] Object of the invention

[0020] The object of the present invention is to at least partially overcome one or several of the disadvantages arising from the prior art.

[0021] Specifically, the present invention is based on the object of providing an anti-resonant element preform from which an anti-resonant hollow optical fiber with good optical properties (such as low light attenuation) can be easily and reproducibly manufactured.

[0022] Another object of the present invention is to provide a method by means of which an anti-resonant element preform with high precision and good optical properties (such as low light attenuation) can be reproducibly manufactured.

[0023] Another object of the present invention is to specify a method for cost-effectively manufacturing a preform of an anti-resonant hollow optical fiber, which avoids the limitations of conventional manufacturing methods.

[0024] Another object of the present invention is to provide a preform for manufacturing an anti-resonant hollow optical fiber, which avoids the limitations of conventional preforms.

[0025] Another object of the present invention is to provide an anti-resonant hollow, which avoids the limitations of conventional hollow optical fibers.

[0026] Preferred embodiments of the present invention

[0027] The features of the independent claims contribute to at least partially fulfilling at least one of the aforementioned objectives. The dependent claims provide preferred embodiments that contribute to at least partially fulfilling at least one of these objectives.

[0028] / 1 / An anti-resonant element preform for manufacturing an anti-resonant hollow fiber, the anti-resonant element preform including in an axial top view

[0029] 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,

[0030] characterized in that

[0031] the first circular element and the first circular arc element are connected to each other at two contact points.

[0032] / 2 / An anti-resonant element preform according to embodiment 1, characterized in that the first circular element and the first circular arc element comprise glass, in particular silica glass, in particular silica glass having a refractive index of 1.4, in particular 1.4 to 3, in particular 1.4 to 2.8, or a polymer, in particular consisting of glass, in particular silica glass, in particular silica glass having a refractive index of at least 1.4, in particular 1.4 to 3, in particular 1.4 to 2.8, or a polymer.

[0033] / 3 / An anti-resonant element preform according to embodiment 1 or 2, characterized in that

[0034] the anti-resonant element preform comprises a circular second circular element having a second circular radius.

[0035] / 4 / An anti-resonant element preform according to any one of the foregoing embodiments, characterized in that the anti-resonant element preform comprises a circular arc-shaped second circular arc element having a second circular arc radius.

[0036] / 5 / An anti-resonant element preform according to any one of the foregoing embodiments, characterized in that the first circular radius has a smaller magnitude than the first circular arc radius.

[0037] / 6 / An anti-resonant element preform according to any one of the foregoing embodiments, characterized in that the first circular arc element is arranged within the first circular element.

[0038] / 7 / An anti-resonant element preform according to any one of embodiments 1 to 5, characterized in that the first circular arc element is arranged outside the first circular element.

[0039] / 8 / A method for manufacturing an anti-resonant element preform according to any one of embodiments 1 to 7, comprising the following method steps:

[0040] (a) Providing a first circular element having a first circular radius, which is circular in an axial top view;

[0041] (b) Providing a first arc element having a first arc radius, which is arc-shaped in an axial top view;

[0042] (c1) Arranging the first arc element within the first circular element such that a first arc end and a second arc end are arranged on the inner side of the first circular element;

[0043] Or

[0044] (c2) Arranging the first arc element outside the first circular element such that a first arc end and a second arc end are arranged on the outer side of the first circular element;

[0045] (d) Connecting the first arc end and the second arc end to the first circular element by forming a second contact point.

[0046] / 9 / The method according to embodiment 8, characterized in that the connection in method step (d) is carried out by means of heat input.

[0047] / 10 / A preform for manufacturing an anti-resonant hollow fiber, the preform comprising a cladding tube, characterized in that at least one anti-resonant element preform according to any one of embodiments 1 to 7 is arranged in the cladding tube.

[0048] / 11 / The preform for manufacturing an anti-resonant hollow fiber according to embodiment 10, characterized in that the at least one anti-resonant element preform is connected to the inner surface of the cladding tube.

[0049] / 12 / The preform for manufacturing an anti-resonant hollow fiber according to embodiment 10 or 11, characterized in that 3 to 10 anti-resonant element preforms are arranged in the cladding tube.

[0050] / 13 / An anti-resonant hollow fiber, which in an axial top view comprises a cladding region and at least one anti-resonant element arranged in the cladding region, and a circular first circular structure having a first circular structural radius and an arc-shaped first arc structure having a first arc structural radius,

[0051] Characterized in that

[0052] The first circular structure and the first arc structure are connected to each other at two contact points.

[0053] / 14 / The anti-resonant hollow fiber according to embodiment 13 is manufactured by stretching a preform according to any one of embodiments 10 to 12.

[0054] General Matters

[0055] The range specifications in this specification also include the values mentioned as limits. Thus, the designation "in the range of X to Y" for the type of variable A means that A can take the value X, the value Y, and the values between X and Y. Thus, the range "at most Y" for the type of variable A restricted on one side thus means Y and values less than Y.

[0056] Some of the described features are related to the term "substantially". The term "substantially" should be understood in such a way that, under actual conditions and manufacturing techniques, a mathematically exact interpretation of terms such as "overlap", "vertical", "diameter", or "parallelism" may never be exactly provided, but can only be applied within certain manufacturing-related error tolerances. For example, "substantially vertical axes" draw an angle of 85 degrees to 95 degrees with each other, and "substantially equal volumes" include a deviation of at most 5 volume %. For example, "a device substantially composed of fused silica" includes > 95 wt% to < 100 wt% of fused silica portion. For example, "substantially completely filling volume B" includes filling > 95 vol% to < 100 vol% of the total volume B. Detailed Description

[0057] The present invention relates to an anti-resonant element preform for manufacturing an anti-resonant hollow fiber, which in an axial top view includes a circular first circular element having a first circular radius and an arcuate first circular arc element having a first circular arc radius.

[0058] In order to overcome the above-mentioned drawbacks in the prior art, it is provided according to the present invention that the first circular element and the first circular arc element are connected to each other at two contact points, wherein the circular arc element is specifically connected to the circular element through a first circular arc end and through a second circular arc end opposite to the first circular arc end. The first circular arc end and the second circular arc end should be understood as the corner points of the first circular arc element, which are visible on the anti-resonant element preform in the axial top view and the first circular arc element extends in an arcuate manner between these corner points.

[0059] An anti-resonant element preform constructed in this way can be manufactured separately from other components for manufacturing an anti-resonant hollow fiber, which is advantageous from a manufacturing-related point of view. Thus, an anti-resonant element preform that differs from the ideal structure (e.g., during its manufacture) can be processed in a relatively cost-effective manner without having to process additional components for manufacturing an anti-resonant hollow fiber. By pre-manufacturing the anti-resonant element preform, uniformity can additionally be obtained throughout the manufacturing batch, which favorably affects the symmetry of the preform manufactured from the anti-resonant element preform and ultimately also favorably affects the symmetry of the anti-resonant hollow fiber. The increased symmetry has a positive impact on the optical properties of the hollow fiber.

[0060] Furthermore, anti-resonant elements manufactured from this type of anti-resonant element preform have proven to be components with improved optical properties in the final hollow fiber, which results in lower optical propagation losses (i.e., including light scattering, diffraction, absorption, and confinement) and thus results in a high data transmission capacity of the final hollow fiber.

[0061] It has become apparent that an arc element connected to a circular element at two contact points allows for a high degree of control of the structural parameters of the anti-resonant element preform and thus enables the provision of an anti-resonant hollow fiber with improved optical properties.

[0062] For example, the improved optical properties of this type of anti-resonant hollow fiber become apparent in an optical attenuation of less than 0.15 dB / km at wavelengths between 1.0 μm and 2.5 μm or in an optical attenuation of less than 1 dB / km at wavelengths up to 0.8 μm. Any type of phenomenon that results in a reduction in the intensity of a propagating signal without thereby affecting its shape is referred to as optical attenuation.

[0063] A component or part of a component is referred to as an anti-resonant element preform that essentially becomes an anti-resonant element in a hollow fiber during the fiber drawing process by means of simple length molding (also referred to as stretching).

[0064] In an axial top view, i.e., a two-dimensional view onto the longitudinal axis, the antiresonator element preform includes a first circular element, which in a three-dimensional view corresponds to a tubular structural element. The first circular element has a substantially uniform first circular radius and is thus designed to be substantially circular, wherein the radius at one 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%. Accordingly, the first circular element has a substantially uniform diameter, wherein the diameter at one point deviates from the diameter at another point of the antiresonator 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, 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, more preferably 0.2 to 1.5 mm.

[0065] In an axial top view, i.e., a two-dimensional view onto the longitudinal axis, the antiresonator element preform includes a first arcuate element, which in a three-dimensional view corresponds to a section of a tubular, substantially circular structural element that is cut out parallel to the longitudinal axis or, in other words, parallel to the bending disk. The first arcuate element has a substantially uniform first arc. Thus, in a three-dimensional view, the first arcuate element represents a section 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 one 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, more preferably in the range of 3 mm to 20 mm. The first arcuate element has a wall thickness in the range of 0.1 mm to 3 mm, preferably 0.1 mm to 2 mm, more preferably 0.2 to 1.5 mm.

[0066] The circular radius and the arc radius will in each case be understood as the outer radius of the corresponding element. The corresponding inner radius is obtained by subtracting the respective wall thickness from the respective outer radius. This also applies to the corresponding diameters.

[0067] The contact points are the locations where the first circular element and the first arcuate element are connected to each other, specifically by means of a material-to-material bond. In one embodiment, the first arcuate element is connected to the first circular element via a first arcuate end and a second arcuate end opposite the first arcuate end. The first circular element and the first arcuate element are connected to each other at exactly two contact points.

[0068] The contact points can be designed differently. In one embodiment, the first circular element and the first arc-shaped element are connected to each other at at least one contact point via fastening means (such as, for example, adhesives, rivets, screws or nails). In a preferred design, the first circular element and the first arc-shaped element are connected to each other by a material-to-material bond at at least one contact point, preferably at two contact points.

[0069] In order to provide an anti-resonator element preform with high structural accuracy and improved optical properties, the first arc-shaped element comprises an arc-shaped 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 the complete circular element, which corresponds to the first arc radius. The advantage hereby is that the contact points are spatially positioned at such a distance from each other that the first arc-shaped element and the first arc are connected to each other without the contact points merging into each other and such that there is one large contact point instead of two non-intersecting contact points. A large contact point would have a negative impact on the optical light guiding properties of the final glass fiber, for example by a local increase in the material part (such as glass) at the large contact point, which can lead to the ovality of the anti-resonator element.

[0070] At the contact points, the first circular element and the first arc-shaped element each draw an exterior angle greater than 10°, preferably greater than 15°, more preferably greater than 20°, most preferably greater than 25°. The exterior angle hereby is not greater than 160°, preferably not greater than 150°, more preferably not greater than 130°. The exterior angle is to be understood as the angle drawn at the contact point between the convex sides of the first circular element and the first arc-shaped element in an axial top view. This allows for providing an anti-resonator element preform with high structural accuracy and improved optical properties.

[0071] In one embodiment, the entire anti-resonator element preform comprises or consists of a material (such as glass, in particular doped or undoped silica glass (SiO2)) that is transparent to the working light of the optical fiber. Doping enables the adaptation of physical properties (such as, for example, the coefficient of thermal expansion). Fluorine, chlorine and / or hydroxyl groups are preferably used as dopants, which reduce the viscosity of the silica glass.

[0072] Embodiments of the anti-resonator element preform are characterized in that the first circular element and the first arc element comprise at least glass (in particular doped or undoped fused silica, in particular fused silica with a refractive index of at least 1.4, in particular from 1.4 to 3), or a polymer (e.g., polymethyl methacrylate, cycloolefin copolymer, polycarbonate or fluoropolymer). In another design, the first circular element and the first arc element are made of glass (in particular doped or undoped fused silica, in particular fused silica with a refractive index of at least 1.4, in particular from 1.4 to 3), or a polymer (e.g., polymethyl methacrylate, cycloolefin copolymer, polycarbonate or fluoropolymer).

[0073] In one embodiment, the first circular element and the arc element are made of the same material. In another design, the first circular element and the first arc element are composed of the same material, specifically composed of undoped or doped fused silica, in particular glass with a refractive index of at least 1.4, specifically from 1.4 to 3, especially from 1.4 to 2.8, with a doping amount not exceeding 0.1 wt%.

[0074] The term "same material" describes the material properties of two components. The two components thus have substantially the same chemical substances. The total mass of different chemical elements in the two parts can thus be less than 1 wt%, especially less than 0.5 wt%, especially less than 0.1 wt%. The difference in the chemical composition of the two parts lies specifically in that the pollutant content is less than 500 wt ppm, especially less than 100 wt ppm, and / or the dopant content is less than 10,000 wt ppm, especially less than 5,000 wt ppm.

[0075] In one embodiment, the anti-resonator element preform consists of a first circular element and a first arc element.

[0076] Embodiments of the anti-resonator element preform are characterized in that the anti-resonator element preform comprises a circular second circular element having a second circular radius.

[0077] The second circular element can have the same characteristics and properties as the first circular element described above, where the second circular radius can be designed to be greater than, less than or equal to the first circular radius.

[0078] In one embodiment, the second circular element is arranged within 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, specifically by material-to-material bonding. In another design, the first arc element and the second circular element are connected to each other, specifically by material-to-material bonding. In another design, the second circular element is connected to the first circular element and to the first arc element, specifically by material-to-material bonding.

[0079] In another embodiment, a first circular element is disposed within a second circular element, wherein the first circular element and the second circular element are preferably connected to each other at the contact points, specifically by means of material-to-material bonding.

[0080] In another embodiment, a second circular element is disposed within a space surrounded by the first circular element and the first circular arc element, wherein the second circular element is specifically connected to the first circular element, connected to the first circular arc element, or connected to the first circular element and the first circular arc element by means of material-to-material bonding.

[0081] An embodiment of the antiresonator element preform is characterized in that the antiresonator element preform includes a circular arc-shaped second circular arc element having a second circular arc radius.

[0082] The second circular arc element may have the same features and characteristics as the first circular arc element described above, wherein the second circular arc radius may be greater than, less than, or equal to the first circular arc radius.

[0083] In one embodiment, the second circular arc element is disposed 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, specifically by means of material-to-material bonding.

[0084] In another embodiment, the second circular arc element is disposed within a space surrounded by the first circular element and the first circular arc element, wherein the second circular arc element is specifically connected to the first circular element at two contact points, connected to the first circular arc element at two contact points, or connected to the first circular element at one contact point and connected to the first circular arc element at one contact point by means of material-to-material bonding.

[0085] Due to the fact that the antiresonator 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 that when only circular elements are used as structural elements to form the antiresonator element preform.

[0086] In one embodiment, the first circular radius and the first circular arc radius have substantially the same value. When only circular elements are used to form the antiresonator element preform, the corresponding structural unit will be inaccessible.

[0087] In another design, the first circular radius has a value greater than the first circular arc radius.

[0088] An embodiment of the antiresonator element preform is characterized in that the first circular radius has a value smaller than the first circular arc radius. When only circular elements are used to form the antiresonator element preform, the corresponding structural unit will be inaccessible.

[0089] The first circular element and the first arcuate element can be arranged differently relative to each other, provided that the two elements are connected to each other at at least two, preferably exactly two, contact points (specifically by means of material-to-material bonding).

[0090] An embodiment of the antiresonator element preform is characterized in that the first arcuate element is arranged within the first circular element. This means that the first arcuate 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 arcuate element is thus arranged on the inner side of the first circular element. This allows for the provision of a circular or (in a three-dimensional view) tubular antiresonator element preform with improved optical properties, and thus it can be easily handled. Such an antiresonator element preform can be easily and with high structural accuracy connected to other components of the preform in order to manufacture an antiresonator hollow fiber.

[0091] An embodiment of the antiresonator element preform is characterized in that the first arcuate element is arranged outside the first circular element. This means that the first arcuate 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 arcuate element is thus arranged on the outer side of the first circular element. This allows for the manufacture of an antiresonator element preform that has a figure-eight profile in an axial top view, or an irregular figure-eight profile depending on the respective radii of the first circular element and the first arcuate element.

[0092] Furthermore, the present invention relates to a method for manufacturing the above-mentioned antiresonator element preform.

[0093] Depending on the desired design of the antiresonator element preform, the method can be carried out in different ways.

[0094] A first embodiment of a method for manufacturing an antiresonator element preform according to any of the above designs at least comprises the following method steps:

[0095] (a) Providing a first circular element having a first circular radius, which is circular in an axial top view;

[0096] (b) Providing a first arcuate element having a first arcuate radius, which is arcuate in an axial top view;

[0097] (c1) Arranging the first arcuate element (300) within the first circular element (200) such that a first arcuate end (305) and a second arcuate end (306) are arranged on the inner side (205) of the first circular element (200);

[0098] (d) Connecting (specifically by material-to-material bonding connection) by forming a second contact point

[0099] The first circular arc end and the second circular arc end.

[0100] A first embodiment of a method for manufacturing an antiresonant element preform for manufacturing the above-mentioned antiresonant element preform, in which, in the preformed case, a first circular arc element is arranged within a first circular element. The first embodiment of the method can be used to manufacture a substantially circular antiresonant element preform.

[0101] A second embodiment of a method for manufacturing an antiresonant element preform according to any one of the above designs at least comprises the following method steps:

[0102] (a) Providing a first circular element having a first circular radius, which is circular in an axial top view;

[0103] (b) Providing a first circular arc element having a first circular arc radius, which is circular arc-shaped in an axial top view;

[0104] (c2) Arranging the first circular arc element outside the first circular element such that a first circular arc end and a second circular arc end are arranged on the outer side of the first circular element;

[0105] (d) Connecting (specifically by material-to-material bonding) the first circular arc end and the second circular arc end by forming a second contact point.

[0106] A second embodiment of a method for manufacturing an antiresonant element preform for manufacturing the above-mentioned antiresonant element preform, in which, in this case, a first circular arc element is arranged outside a first circular element. The second embodiment of the method can be used to manufacture an antiresonant element, the contour of which 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 circular arc element.

[0107] The connection in method step (d) can be carried out in different ways in all embodiments of the method, such as via adhesion, threaded connection, riveting, welding, stapling or clamping.

[0108] An embodiment of a method for manufacturing the above-mentioned antiresonant element preform is characterized in that the connection in method step (d) is carried out by means of heat input.

[0109] The heat input is specifically used for material-to-material bonding of the first circular element and the first circular arc element at the contact point. The heat input must be carried out in such a way that material-to-material 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 element at least partially changes from a solid state to a liquid state (especially a viscous state).

[0110] The thermal input can be implemented in different ways, for example by means of:

[0111] - Flame-based processes: based on the oxidation of exothermic reaction gases. An example is the use of hydrogen (also known as "H2") as the exothermic reaction combustion gas (flame hydrolysis). It reacts with oxygen (also known as "O2") in the air; or

[0112] - Flameless processes: using other systems that are heated and do not require an open flame. An example is the use of a resistor that can convert electrical energy into heat (thermal energy).

[0113] Furthermore, the present invention relates to a preform for manufacturing an anti-resonant hollow fiber, the preform comprising a cladding tube, characterized in that at least one of the above-mentioned anti-resonant element preforms is arranged in the cladding tube.

[0114] A preform is a component from which an anti-resonant hollow fiber can be drawn. In an alternative, the preform can be further processed into a secondary preform, from which an anti-resonant hollow 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).

[0115] The cladding tube is a tubular element made essentially of silica glass, in which at least one of the above-mentioned anti-resonant element preforms is arranged. When the final preform is drawn into the final fiber, the cladding tube surrounds the hollow of the anti-resonant hollow 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.

[0116] At least one anti-resonant element preform can be arranged in the cladding tube in different ways.

[0117] Embodiments of the preform are characterized in that at least one anti-resonant element preform is connected to the inner surface of the cladding tube, specifically by means of a material-to-material bond. In one embodiment, the anti-resonant element preform is connected to the cladding tube via a first circular element. In another design, the anti-resonant element preform is connected to the cladding tube via a first circular arc element, where in the case of these anti-resonant elements, the first circular arc element is arranged outside the first circular element.

[0118] To construct the preform, different numbers of anti-resonant elements can be arranged in the cladding tube.

[0119] Embodiments of the preform are characterized in that 3 to 10, preferably 3 to 8, more preferably 4 to 6 anti-resonant element preforms are arranged in the cladding tube.

[0120] In one embodiment, only those anti-resonant element preforms having the properties and characteristics of the above anti-resonant element preforms are arranged within the cladding tube. In a further design, at least one anti-resonant element preform arranged within the cladding tube has other characteristics and properties different from those of the above anti-resonant element preforms.

[0121] Furthermore, the present invention relates to an anti-resonant hollow optical fiber which, in an axial top view, comprises a cladding region and at least one anti-resonant element arranged in the cladding region, the anti-resonant element comprising a circular first circular structure having a first circular structure radius and an arcuate first arcuate structure having a first arcuate structure radius, characterized in that the first circular structure and the first arcuate structure are connected to each other at two contact points.

[0122] The anti-resonant hollow optical fiber can be manufactured from the above preform, specifically by drawing, wherein at least a part of the cladding region of the anti-resonant hollow optical fiber is formed by the cladding tube of the preform, and at least one anti-resonant element of the anti-resonant hollow optical fiber is formed by at least one anti-resonant element preform of the preform. Thus, the first circular structure is constructed from a first circular element, and the first arcuate structure is constructed from a first arcuate element. The corresponding contact points are maintained.

[0123] The preform is drawn during the drawing. The drawing is preferably carried out proportionally such that, for example, the shape and arrangement of the components or parts of the preform (in particular the first circular element and the first arcuate element) are reflected in the final drawn product.

[0124] In embodiments of the anti-resonant hollow optical fiber, the cladding region corresponds to the drawn cladding tube. In a further design, the cladding region corresponds to the cladding tube and a covering tube which is added to the cladding tube before or during the drawing. "Added" is to be understood as specifically connecting the cladding tube and the covering tube by substance-to-substance bonding, which is specifically carried out by means of heat input and preferably by using a negative pressure applied between the cladding tube and the covering tube.

[0125] In order to draw and produce an anti-resonant hollow optical fiber from the preform, the preform can be guided vertically through a furnace. The lower end of the preform is thereby heated to the drawing temperature, and the anti-resonant hollow optical fiber is drawn in a tapered form from the lower end, wherein the drawn optical fiber is subsequently cooled from the drawing temperature by means of an air flow directed opposite to the drawing direction.

[0126] The features and characteristics disclosed in the description may be important for the various embodiments of the invention claimed, individually and in any combination with each other. The features and characteristics disclosed for the anti-resonant element preform, preform or anti-resonant hollow fiber are also disclosed for the method and vice versa.

[0127] Drawings

[0128] The invention will be further illustrated below in an exemplary manner with the aid of the drawings. The invention is not limited to the drawings.

[0129] Figure 1 An axial top view onto an anti-resonant element preform comprising a first circular element and a first circular arc element is shown,

[0130] Figure 2 Another embodiment of the anti-resonant element preform is shown,

[0131] Figure 3 Another embodiment of the anti-resonant element preform is shown,

[0132] Figure 4 Another embodiment of the anti-resonant element preform is shown,

[0133] Figure 5 Another embodiment of the anti-resonant element preform is shown,

[0134] Figure 6 Another embodiment of the anti-resonant element preform is shown,

[0135] Figure 7 Another embodiment of the anti-resonant element preform is shown,

[0136] Figure 8 Another embodiment of the anti-resonant element preform is shown,

[0137] Figure 9 Another embodiment of the anti-resonant element preform is shown,

[0138] Figure 10 An axial top view onto a preform of an anti-resonant hollow fiber is shown,

[0139] Figure 11 An axial top view onto an anti-resonant hollow fiber is shown, and

[0140] Figure 12 A method for manufacturing an anti-resonant element preform is shown. Description of the Drawings

[0141] Figure 1The antiresonator element preform 100 is shown in an axial top view. The antiresonator element preform 100 includes a circular first circular element 200 having a first circular radius 250. A first arc element 300 having a first arc radius 350 is disposed within the first circular element 200. In the illustrated embodiment of the antiresonator element preform 100, the first circular radius 250 and the first arc radius 350 have the same value. The first circular element 200 and the first arc element 300 are connected to each other at two contact points 400, specifically by material-to-material bonding. At the contact points 400, an exterior angle 150 is drawn on the convex side of the first arc element 300 and the inner side of the first arc in each case, and this exterior angle has the same value due to the symmetric arrangement of the antiresonator element preform 100 in the illustrated embodiment. In additional, non-illustrated embodiments, the two exterior angles 150 are not the same. In the illustrated embodiment, the first circular element 200 and the first arc element 300 are formed of the same material, in particular doped or undoped fused silica.

[0142] Figure 2 Another embodiment of the antiresonator element preform 100a is shown. According to Figure 2 the embodiment is largely corresponding to the embodiment described above and shown in Figure 1 such that for the sake of avoiding repetition, reference is made to the above description. Structures repeated from the Figure 1 description have the same reference numerals. Compared with the structure shown in Figure 1 the modified structures have the same reference numerals with an additional letter a.

[0143] In the illustrated embodiment, the first circular radius 250 has a value larger than the first arc radius 350a, whereby the exterior angle 150a is greater than the exterior angle 150 according to Figure 1 the embodiment. Due to the smaller first arc radius 350a compared with Figure 1 the contact points 400a are also positioned closer together compared with the contact points 400 Figure 1 of the embodiment.

[0144] Figure 3 Another embodiment of the antiresonator element preform 100b is shown. According to Figure 3 the embodiment is largely corresponding to the embodiment described above and shown in the above figures such that for the sake of avoiding repetition, reference is made to the above description. Structures repeated from the description of the above figures have the same reference numerals. Compared with the structures shown in the above figures, the modified structures have the same reference numerals with an additional letter b. Compared with Figure 2Compared with Embodiment 100a, another embodiment 100b of the anti-resonant element preform has an arcuate second arcuate element 310 with a second arc radius 360. Just like the first arcuate element 300a, the second arcuate element 310 is disposed within the first circular element 200 and is 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 additional, unillustrated embodiments, the first arc radius 350a and the second arc radius 360 may have different values. In the illustrated embodiment, the first arcuate element 300a and the second arcuate element 360 are disposed on opposite inner sides of the first circular element 200 such that the corresponding convex sides of the first arcuate element 300a and the second arcuate element 310 face each other. In additional, unillustrated embodiments, the first arcuate element 300a and the second arcuate element 310 are disposed closer to each other spatially on the inner side of the first circular element 200.

[0145] Figure 4 Another embodiment of the anti-resonant element preform 100c is shown. According to Figure 4 the embodiment corresponds largely to the embodiments described above and shown in the above figures, such that for the sake of avoiding repetition, reference is made to the above description. Structures repeated from the description of the above figures have the same reference numerals. Compared with the structures shown in the above figures, modifications of the structures have the same reference numerals with an additional letter c.

[0146] In the illustrated embodiment, the second arcuate element 310c is disposed on the same side as the first arcuate element 300 within the first circular element 200, where the first arc radius 350 and the second arcuate element 360c have the same value. The first arcuate element 350 and the second arcuate element 310c are disposed relative to each other such that the convex side of the second arcuate element 310c faces the concave side of the first arcuate element 300. In additional, unillustrated embodiments, the first arcuate element 350 and the second arcuate element 310c are disposed relative to each other such that the concave side of the second arcuate element 310c faces the concave side of the first arcuate element 350.

[0147] Figure 5 Another embodiment of the anti-resonant element preform 100d is shown. According to Figure 5 the embodiment corresponds largely to the embodiments described above and shown in the above figures, such that for the sake of avoiding repetition, reference is made to the above description. Structures repeated from the description of the above figures have the same reference numerals. Compared with the structures shown in the above figures, modifications of the structures have the same reference numerals with an additional letter d.

[0148] In the illustrated embodiment of the antiresonant element preform 100d, the second arcuate element 310d is disposed within the first circular element 200 on the same side as the first arcuate element 300, as Figure 4 shown, wherein the first arcuate radius 350 has a value smaller than the second arcuate radius 360d. The first arcuate element 300 and the second arcuate element 360 are disposed at the same point of the first circular element 200 such that the contact point 400 of the first arcuate element 400 and the contact point 330d of the second arcuate element 330 coincide with the first arc 200. The first arcuate element 350 and the second arcuate element 310d are disposed relative to each other such that the convex side of the second arcuate element 310d faces the concave side of the first arcuate element 300. In an additional, not shown embodiment, the first arcuate element 350 and the second arcuate element 310d are disposed relative to each other such that the concave side of the second arcuate element 310d faces the concave side of the first arcuate element 350.

[0149] Figure 6 Another embodiment of the antiresonant element preform 100e is shown. According to Figure 6 the embodiment largely corresponds to the embodiments described above and shown in the above figures such that, to avoid repetition, reference is made to the above description. Structures repeated from the description of the above figures have the same reference numerals. Compared to the structures shown in the above figures, modifications of the structures have the same reference numerals with an additional letter e.

[0150] The illustrated embodiment of the antiresonant element preform 100e has a second circular element 210 with a second circular radius 260. The second circular element 210 is disposed within the space formed by the inner side of the first circular element 200 and the concave side of the first arcuate element 300. Thereby, the second circular element 210 is connected to the first circular element 200. In an additional, not shown embodiment, the second circular element 210 is connected to the first arcuate element 300 or is connected to the first circular element 200 and the first arcuate element 300. In an additional, not shown embodiment, the second circular element 210 is disposed within the space formed by the inner side of the first circular element 200 and the convex side of the first arcuate element 300, wherein the second circular element 210 is connected to the first arcuate element 300 and / or the first circular element 200.

[0151] Figure 7 Another embodiment of the antiresonant element preform 100f is shown. According to Figure 7 the embodiment largely corresponds to the embodiments described above and shown in the above figures such that, to avoid repetition, reference is made to the above description. Structures repeated from the description of the above figures have the same reference numerals. Compared to the structures shown in the above figures, modifications of the structures have the same reference numerals with an additional letter f.

[0152] In the illustrated embodiment, the second circular element 210 is disposed within the space formed by the concave side of the second arcuate element 210d and the inner side of the first circular element 200. The second circular element 210 is thereby connected to the first circular element 200. In additional, unillustrated embodiments, the second circular element 210 is connected to the second arcuate element 210 or is connected to the first circular element 200 and the second arcuate element 310d. In additional, unillustrated embodiments, the second circular element 210 is disposed within the space formed by the convex side of the first arcuate element 300 and the inner side of the first circular element 200. In an additional embodiment, the second circular element 210 is disposed within the space formed by the first arcuate element 300 and the second arcuate element 310d, wherein the second circular element 210 is connected to the first arcuate element 300, the second arcuate element 310d, or the first arcuate element 300 and the second arcuate element 310d.

[0153] Figure 8 Another embodiment of the anti-resonator element preform 100g is shown. According to Figure 8 the embodiment largely corresponds to the embodiment described above and shown in the above figures, such that for the sake of avoiding repetition, reference is made to the above description. Structures repeated from the description of the above figures have the same reference numerals. Compared to the structures shown in the above figures, modifications of the structures have the same reference numerals with an additional letter g.

[0154] The first arcuate element 300g is disposed 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 arcuate element 300g each have an outer angle 150g at the two contact points 400. The profile of the anti-resonator element preform 100g substantially corresponds to the profile of 8. In the illustrated embodiment, the first arcuate radius 350g has a value greater than the first circular radius 250. In additional, unillustrated embodiments, the first arcuate radius 350g has a value equal to or less than the first circular radius 250.

[0155] Figure 9 Another embodiment of the anti-resonator element preform 100h is shown. According to Figure 9 the embodiment largely corresponds to the embodiment described above and shown in the above figures, such that for the sake of avoiding repetition, reference is made to the above description. Structures repeated from the description of the above figures have the same reference numerals. Compared to the structures shown in the above figures, modifications of the structures have the same reference numerals with an additional letter h.

[0156] The illustrated embodiment has a first arc element 300g disposed outside the first circular element 200 and a second circular element 210h disposed within the first circular element 200 having a second circular element radius 260h, wherein the second circular element 210h and the first arc element 300g are disposed on opposite sides of the first circular element 200. In additional, unillustrated embodiments, the first arc element 300g and the second circular element 210h are disposed on the same side of the first circular element 200. In additional, unillustrated embodiments, the second circular element 210h is disposed within the space formed by the concave side of the first arc element 300g and the first circular element 200, wherein the second circular element 210g may be connected to the first circular element 200 and / or the first arc element 300g.

[0157] Figure 10 A preform 500 is shown, which includes a cladding tube 550 and four anti-resonant element preforms 100 disposed within the cladding tube 550 according to Figure 1 . In additional, unillustrated embodiments, the preform 500 includes a different number (e.g., 2 to 10) of anti-resonant element preforms 100 and / or anti-resonant element preforms of a different shape according to the present invention (e.g., according to one of Figures 2 to 9 ), or the preform 500 includes two or more different embodiments of anti-resonant element preforms according to the present invention (e.g., according to Figures 1 to 9 ).

[0158] In the illustrated embodiment, the four anti-resonant element preforms 100 are connected to the inner side of the cladding tube 550. The distribution of the anti-resonant elements 100 on the inner side of the cladding tube 500 is symmetric such that a symmetric anti-resonant hollow-core optical fiber can be manufactured from the preform 500 by stretching the preform 500, which has improved optical properties. The four anti-resonant element preforms 100 are disposed at the cladding tube 550 in such a way that the convex sides of the respective first arc elements 300 are aligned in the direction of the center 510 of the preform 500. In additional, unillustrated embodiments, the concave sides of the first arc elements 300 may be aligned in the direction of the center 510, or a plurality of arc elements 300 may be aligned with their respective convex sides in the direction of the center 510, and a plurality of first arc elements 300 may be aligned with their respective concave sides. The arrangement of the arc elements 300 is preferably designed symmetrically with respect to the center 510.

[0159] Figure 11 Shown is, for example, by stretching according to Figure 10An anti-resonant hollow fiber 600 fabricated from a preform 500 includes a cladding region 550' and four anti-resonant elements 100' disposed within the cladding region 550'. In an additional, not shown embodiment, the anti-resonant hollow fiber 600 includes a different number (e.g., 2 to 10) of anti-resonant elements 100'. The anti-resonant elements 100' have a circular first circular structure 200' and an arcuate first arc structure 300'. The first arc structures 300' are each connected to the corresponding first circular structure 200' at two contact points 400'. In the shown embodiment, the anti-resonant hollow fiber 600 has a structure that can be obtained by elongating the preform 500 according to Figure 10 In an additional, not shown embodiment, the anti-resonant hollow fiber has differently shaped anti-resonant elements 100' that can be obtained by elongating by means of different anti-resonant element preforms according to the present invention (e.g., according to Figures 2 to 9 ). The four anti-resonant elements 100' are arranged in the cladding region 550' such that the convex sides of the corresponding first arc structures 300' are aligned in the direction of the hollow fiber center 610 of the anti-resonant hollow fiber 600. In an additional, not shown embodiment, the concave sides of the first arc structures 300' can be aligned in the direction of the hollow fiber center 610, or multiple arc structures 300' can be aligned with the corresponding convex sides in the direction of the hollow fiber center 610, and multiple first arc structures 300' can be aligned with the corresponding concave sides. The arrangement of the arc structures 300' is preferably designed symmetrically with respect to the hollow fiber center 610.

[0160] Figure 12 A method 700 for manufacturing an anti-resonant element preform 100 is shown. 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.

[0161] Method step 710 includes providing a first circular element 200 that is circular in an axial top view, and method step 720 includes providing first arc elements 300, 300a, 300g that are arcuate in an axial top view.

[0162] The first circular element 200 and the first arc elements 300, 300a, 300g can be arranged differently relative to each other.

[0163] In a first embodiment of method 700, the first arc-shaped elements 300, 300a and the first circular element 200 are arranged relative to each other in method step 730 in such a way that the first arc-shaped elements 300, 300a are arranged on the inner side of the first circular element 200 via the first arc ends and via the second arc ends opposite the first arc ends. The first arc-shaped elements 300, 300a are thus arranged within the first circular element 200.

[0164] In a second embodiment of method 700, the first arc-shaped 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 arc-shaped element is arranged on the outer side of the first circular element 200 via the first arc end and via the second arc end. The first arc-shaped element 300g is thus arranged outside the first circular element 200.

[0165] In method step 750, the first arc ends and the second arc ends and thus the first arc-shaped elements 300, 300a, 300g are connected to the first circular element 200. The connection in method step 750 can be realized in different ways, for example via adhesion, clamping or fastening means (e.g., via screws, rivets or nails). In a preferred embodiment, the connection in method step 750 is carried out by means of heat input.

[0166] The heat input is specifically used to connect the two elements by material-to-material bonding at the contact points 400, 400a, 400g of the first circular element 200 and the first arc-shaped elements 300, 300a, 300g. The heat input is carried out in such a way that material-to-material bonding between the materials of the two elements is possible. This can be achieved as follows: at least at the contact points 400, 400a, 400g, the surfaces of the elements at least partially change from a solid state to a liquid state (in particular a viscous state).

[0167] The heat input can be realized in different ways, for example by means of:

[0168] - Flame-based processes: based on the oxidation of exothermic reaction gases. An example is the use of hydrogen gas (also referred to as "H2") as the combustion gas (flame hydrolysis). Thereby hydrogen reacts with oxygen in the air (also referred to as "O2"); or

[0169] - Flameless processes: the use of other systems that are heated and do not require an open flame. An example is the use of a resistor that can convert electrical energy into heat energy (heat).

[0170] Reference Signs in the Drawings

[0171] 100, 100a, 100b, 100c, 100d antiresonant element preforms

[0172] 100e, 100f, 100g, 100h

[0173] 100' anti-resonant element

[0174] 150, 150a, 150g outer angle

[0175] 200 first circular element

[0176] 200' first circular structure

[0177] 210, 210h second circular element

[0178] 250 first circular radius

[0179] 260, 260h second circular element radius

[0180] 300, 300a, 300g first circular arc element

[0181] 300' first circular arc structure

[0182] 310, 310c, 310d second circular arc element

[0183] 330, 330c, 330d contact point of the first circular element and the second circular arc element

[0184] 350, 350a, 350g first circular arc radius

[0185] 360, 360c, 360d second circular arc radius

[0186] 400, 400a, 400g contact point of the first circular element and the first circular arc element

[0187] 400' contact point of the first circular structure and the first circular arc structure

[0188] 500 preform

[0189] 510 center of the preform

[0190] 550 cladding tube

[0191] 550' cladding region

[0192] 600 anti-resonant hollow fiber

[0193] 610 center of the anti-resonant hollow fiber

[0194] 700 method

[0195] 710 provide the first circular element

[0196] 720 provide the first circular arc element

[0197] 730 Arrange the first arc element within the first circular element

[0198] 740 Arrange the first arc element outside the first circular element

[0199] 750 Connect

Claims

1. An anti-resonant element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) for manufacturing an anti-resonant hollow fiber (600), the anti-resonant element preform including, in an axial top view, a circular first circular element (200) having a first circular radius (250) and an arcuate first arcuate element (300, 300a, 300g) having a first arc radius (350, 350a, 350g). It is characterized in that The first circular element (200) and the first arcuate element (300, 300a, 300g) are connected to each other at two contact points (400, 400a, 400g), and the anti-resonant element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) includes a circular second circular element (210) having a second circular radius (260).

2. The anti-resonator 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 arcuate element (300, 300a, 300g) include glass or polymer.

3. The anti-resonant 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 arcuate element (300, 300a, 300g) are composed of glass or polymer.

4. The anti-resonant element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to claim 2 or 3, wherein the glass is fused silica.

5. The anti-resonator element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to any one of claims 1 to 3, characterized in that, The anti-resonant element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) includes an arcuate second arcuate element (310) having a second arc radius (360).

6. The anti-resonator element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to any one of claims 1-3, characterized in that, The first circular radius (250) has a value smaller than the first arc radius (350, 350a, 350g).

7. The anti-resonant element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to any one of claims 1-3, characterized in that, The first arcuate element (300, 300a) is arranged inside the first circular element (200).

8. The anti-resonator element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to any one of claims 1 to 3, characterized in that, The first arcuate element (300g) is arranged outside the first circular element (200).

9. A method (700) for manufacturing the anti-resonant element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to any one of claims 1 to 8, the method including the following method steps: (a) Providing (710) a first circular element (200) that is circular in an axial top view; (b) Providing (720) a first arcuate element (300, 300a, 300g) that is arcuate in an axial top view; (c1) Arranging (730) the first arcuate element (300, 300a) inside the first circular element (200) such that a first arc end and a second arc end are arranged on an inner side of the first circular element (200); Or (c2) Arrange (740) the first arc element (300g) outside the first circular element (200) such that the first arc end and the second arc end are arranged on the outer side of the first circular element (200); (d) Connect (750) the first arc end and the second arc end to the first circular element (200) by forming second contact points (400, 400a, 400g).

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

11. A preform (500) for manufacturing an anti-resonant hollow fiber (600), the preform comprising a cladding tube (550), characterized in that, At least one anti-resonant element preform (100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100h) according to any one of claims 1 to 8 is arranged in the cladding tube (550).

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

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

14. An anti-resonant hollow optical fiber (600), the anti-resonant hollow optical fiber comprising a cladding region (550') and at least one anti-resonant element (100') arranged in the cladding region (550') in an axial top view, the anti-resonant element comprising a circular first circular structure (200') having a first circular structure radius and an arcuate first arc structure (300') having a first arc structure radius, 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 anti-resonant hollow optical fiber (600) is manufactured by drawing a preform (500) according to any one of claims 11 to 13.

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