Waveguides using transverse anderson localization and having an optically active material for improved contrast

Abstract

The disclosure relates to waveguides for transmitting electromagnetic waves, for example image guides for transmitting image information, and to methods of manufacturing waveguides, which operate using transverse Anderson localization and may have an optically active material for improved contrast.

Description

[0001] Waveguides using Transverse Anderson Localization and having an Optically Active Material for Improved Contrast

[0002] The disclosure relates to waveguides for transmitting electromagnetic waves, for example image guides for transmitting image information, and to methods of manufacturing waveguides, which operate using transverse Anderson localization and may have an optically active material for improved contrast.

[0003] Background of the Disclosure:

[0004] Traditional image guides typically comprise a plurality of individual optical fibers, each of which comprises a core and a cladding surrounding the core, the optical fibers being assembled as a bundle and arranged in cross-section in a grid with a one-to-one relationship between the light input surface and the light output surface to form a plurality of pixels. Basically, each pixel serves to transmit a brightness value or color information via the image guide.

[0005] It is often desirable to have the highest possible resolution of the image guide. In principle, a high resolution can be achieved by reducing the diameter of the individual optical fibers. However, due to physical laws, the resolution cannot be increased linearly because, as the diameters of the individual optical waveguides become smaller and smaller, an increasing proportion of the field distribution of the transmitted modes exceeds the dimensions of the optical waveguides, in particular the cladding, which leads to increased crosstalk between adjacent optical fibers and thus to decreasing the sharpness of the edges where light should not propagate.

[0006] One approach to provide image guides with higher resolution and better Michelson contrast is based on the wave phenomenon of transverse Anderson localization (TAL). This takes advantage of the fact that a distribution of refractive indices over the cross-section of the image guide with simultaneous invariance of the cross-section along the length of the image guide leads to a confinement of the coupled light due to destructive interference. The distribution can be for example any aperiodic or nonregular pattern or the distribution can be “random” as that term is described in WO 2021 / 259926, the entire contents of which are hereby incorporated by reference. In practice, for example, a large number of individual fibers with different refractive indices can be combined to form a transverse Anderson localization optical waveguide. If a light beam is coupled into such a waveguide, it propagates along the length of the waveguide with a transverse extension limited in cross-section.

[0007] Summary of the Disclosure:

[0008] The present disclosure provides a waveguide for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, comprising: a fiber bundle extending along the transport direction comprising: (a) a distribution of a plurality of first structural elements, (b) a distribution of a plurality of second structural elements that have a different refractive index from the first structural elements, such that the waveguide transmits electromagnetic waves along the transport direction according to the principle of transverse Anderson localization, and (c) a distribution of a plurality of third structural elements comprising an optically active material, the optically active material extending along the transport direction and having a different longitudinal center axis than the first structural elements and the second structural elements, wherein the optically active material comprises 10% or less of a total cross-sectional area of the fiber bundle, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 40% or less of the first structural elements, and wherein the distribution of the plurality of third structural elements provides an extended adjacent factor 60% or more for the second structural elements.

[0009] The present disclosure also provides a waveguide for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, comprising a fiber bundle extending along the transport direction comprising: (a) a distribution of a plurality of first structural elements, (b) a distribution of a plurality of second structural elements that have a different refractive index from the first structural elements, such that the waveguide transmits electromagnetic waves along the transport direction according to the principle of transverse Anderson localization, and wherein the waveguide has a Michelson contrast at least 0.8.

[0010] Detailed Description of the Disclosure:

[0011] The waveguide can have a plurality of fiber bundles. The first structural elements and the second structural elements may have different refractive indices with or without different cross-sectional areas. The first structural elements may be formed from a single material, as can each of the other structural elements.

[0012] When the waveguide functions utilizing the principle of transverse Anderson localization, at least two different types of structural elements can be used, namely a first type having a first refractive index and a second type having a second refractive index which is different than the first refractive index. Accordingly, the plurality of structural elements may each comprise at least one structural element of the first type as well as at least one structural element of the second type. Of course, also more than two different types, e.g. three or more different types of structural elements may be used. For example, if the fiber bundles are surrounded by a non-leachable cladding, which may be provided for mechanical purposes, the non-leachable cladding can be considered to be a structural element. Furthermore, in embodiments where the waveguide is a leached fiber bundle, the leachable cladding that surrounds each optical fiber bundle can be considered to be a structural element, although the leachable cladding is leached away and is not present in the middle along the length of the final waveguide. In all embodiments, the waveguide may be surrounded by a non-leachable mechanical protection buffer. A leachable material is a material that can be dissolved by acids, bases, deionized water or organic solvents at least two times faster than the elements that are not intended to be fully removed in the conventional processes of forming flexible optical fiber bundles, such as the structural elements and the optional non-leachable cladding.

[0013] The structural elements can each extend along the transport direction as well as over the cross-section of the waveguide in such a way that a plurality of cross-sectional regions is defined in the cross-section of the waveguide, each corresponding to the cross-section of a single structural element. Accordingly, the structural elements can extend side by side, for example parallel to one another, along the transport direction of the waveguide and their cross-sections can each occupy a planar portion of the crosssection of the waveguide and therefore can each define a cross-sectional region of the cross-section of the waveguide. The cross-sectional regions can thus correspond to the surface regions formed by the structural elements when looking at a cross-sectional surface of the waveguide, for example the light entry or light exit surface.

[0014] The first structural element may differ from the second structural element by its refractive index, cross- sectional area and / or composition. The cross-sectional regions of the structural elements may have geometries which are non-uniform with respect to one another, for example non-uniform diameters. However, the geometries of the cross- sectional regions can also be of the same type.

[0015] The structural elements can be arranged in such a way that electromagnetic waves transmitted by the waveguide remain localized in a direction extending transversely to the transport direction.

[0016] The structural elements can be arranged mathematically in such a way that the waveguide has a reproducible structure for example in such a way that further waveguides with a structure identical or substantially similar to the waveguide can be produced, for example as described in WO 2021 / 259926, the entire contents of which are incorporated by reference herein. The reproducible structure can be an intentional distribution of each of the structural elements in certain locations during manufacture. Since each fiber bundle may have thousands or millions of structural elements, one way to produce a reproducible fiber bundle is to distribute the structural elements in a desired manner to form a preform, then combine that distribution with an identical or substantially similar distribution to form a combined preform, then combine the combined preform with another combined preform, and so on to form the reproducible fiber bundle. A reproducible fiber bundle permits the structural elements to be distributed in an intentional manner to produce an intentionally designed fiber bundle to maximize the performance characteristics of the fiber bundles and waveguides described herein.

[0017] The ratio of the total area of the cross-sectional regions of the first structural elements to the total area of the cross-sectional regions of the second structural elements can be, for example, in a range between 1 :150 and 150:1 , 1 :100 and 100:1 , 1 :50 and 50:1 ; 1 :10 and 10:1, 3:7 and 7:3, 4:6 and 6:4, or 5:5. This can also be understood as a degree of filling.

[0018] The refractive index of the first structural elements and the refractive index of the second structural elements may differ by at least 10 , for example by at least 103, for example by at least 102, for example by at least 101, for example by at least 1 , for example by at least 2, for example by at least 3, for example by at least 4.

[0019] With respect to the transverse extent of the structural elements, it may be provided that the diameter of each structural element is 100 nm to 50 pm, 500 nm to 20 pm, or 650 nm to 10 pm. With respect to the transverse extent of the fiber bundles, it may be provided that the diameter of each fiber bundle is 10 to 250 pm, 20 to 150 pm, 20 to 100 pm, or 30 to 60 pm.

[0020] Furthermore, it can be provided that at least one cross-sectional region of each structural element has a diameter which lies between 0.1 times and 10 times the average wavelength of a wavelength range of electromagnetic waves to be preferably transmitted, between 0.2 times and 5 times the average wavelength, or between 0.5 times and 2 times the average wavelength.

[0021] The diameter of the waveguide can be 0.4 to 50 mm.

[0022] In the case of leached fiber bundle waveguides, the fiber bundles are distinguishable from each other by the leachable cladding that surrounds the fiber bundles, which is leached away other than at the end of the waveguide, if a leachable cladding is used. In the case of wound fiber bundle waveguides, the fiber bundles are distinguishable from each other due to the interstitial bonding agent at the ends of the waveguide.

[0023] With respect to the geometric shape of the structural elements and the fiber bundles, it may be provided that the structural elements and the fiber bundles have a non-circular or polygonal geometry, for example pentagonal or hexagonal.

[0024] The first structural elements can be formed as a, for example monolithic, base body with or from a first medium, wherein the first medium has the first refractive index. The second structural elements may be formed as cavities in the base body, wherein the cavities preferably have the second refractive index, for example by the refractive index of liquid, air or a gas which may be present as a medium in the cavities. The structural elements of the second type can be formed as a, for example monolithic, base body with or from a second medium, wherein the second medium has the second refractive index. One or more of the monolithic base bodies of the first medium can be fused to one or more of the monolithic base bodies of the second medium prior to drawing and the fused base bodies can be drawn to form a waveguide comprising a plurality of the first base bodies and a plurality of the second base bodies.

[0025] A base body with cavities can be produced or manufactured in various ways. The cavities in the base body can be formed by additive construction of the base body, for example by means of 3D printing processes. Alternatively or additionally, cavities may be subtractively introduced into the base body, for example as bores which are introduced into the base body for example by abrasive material processing methods, for example mechanical drilling. Depending on the method used, bores are not exclusively limited to round geometries.

[0026] The waveguide may be manufactured in a multi-train process, for example such that the waveguide comprises, in addition to the first plurality of structural elements, at least a second plurality of structural elements, wherein the waveguide has, in cross-section, at least two surface regions which each comprise the cross-sectional regions of one of the two pluralities of structural elements, and these cross-sectional regions may have an identical structure apart from a rotation and / or a reflection.

[0027] With regard to the length of the waveguide along the transport direction, it may be provided that the waveguide has a length along the transport direction of at least 10 millimeters, of at least 20 millimeters, of at least 50 millimeters, or of at least 100 millimeters.

[0028] In the case that the waveguide is formed as a base body with cavities, the cavities may be filled with a second medium or with the second structural element, the second medium or the second structural element having the second refractive index.

[0029] With regard to the materials, it may be provided that at least one structural element, for example the or a first structural element formed as a base body comprises or consists of one or more of the following materials: glass (including oxide and non-oxide materials such as chalcogenides), quartz glass, polymer, crystal, monocrystal, polycrystalline material, and / or glass ceramic.

[0030] Furthermore, the or a first structural element formed as a base body may comprise or consist of a material as a medium which, in the wavelength range to be transmitted, esp. from 2 m to 20 pm, for example an attenuation of less than 100 dB / m, less than 50 dB / m, less than 10 dB / m, less than 1 dB / m, for example an infrared-transmissive material, for example a chalcogenide, may comprise at least one element from the group comprising oxygen, sulphur, selenium, and tellurium, and at least one element from the group comprising arsenic, germanium, phosphorus, antimony, lead, boron, aluminum, gallium, indium, titanium, and sodium.

[0031] Furthermore, optically active materials may be provided, e.g. as part of a medium or a filling, as a layer or coating or other modification on the surfaces of an assembly of structural elements, or as third structural elements. Thus, for example, a modification of the guided electromagnetic waves, e.g. in the sense of an amplification or conversion, can be achieved.

[0032] The first structural elements may be formed as rod-shaped or tubular bodies with or made of a first medium, the first medium having the first refractive index.

[0033] The second structural elements can be formed as rod-shaped or tubular bodies with or from a second medium, the second medium having the second refractive index, and / or as cavities in the first structural elements, the cavities forming the second refractive index or being filled with a second medium having the second refractive index.

[0034] In the case where the second structural elements are present as filled cavities in the first structural elements, the structural elements may be formed as core-shell systems such that the core corresponds to the filled cavity.

[0035] Rod-shaped or tubular bodies are not to be understood exclusively as those with a round cross- sectional geometry.

[0036] The disclosure further relates to a method for producing a waveguide, for example a waveguide having one or more of the features described herein, for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, the method comprising forming a fiber bundle that extends along the transport direction comprising a plurality of first structural elements and a plurality of second structural elements that differ from the first structural elements, whereby electromagnetic waves introduced into the proximal end are confined within a cross-sectional region transverse to the transport direction due to the difference between the first structural elements and the second structural elements.

[0037] Description of the Drawings:

[0038] Fig. 1 : Schematic illustration of cross-sections of various fiber bundles having (a), (b), (c) at least two types of structural elements and (d), (e) at least three types of structural elements, respectively, wherein the cross-sectional areas of the structural elements may differ. Fig. 2: Schematic perspective views of two fiber bundles having (a) two types of structural elements that are non-uniformly distributed and (b) a plurality of structural elements of non-uniform refractive indices (plurality of types) and / or non-uniform geometries (diameters).

[0039] Fig. 3: Schematic cross-section of a fiber bundle with two types of structural elements that are non- uniformly distributed on a hexagonal lattice.

[0040] Fig. 4: Schematic perspective views of (a) fiber bundles assembled into a preform, which are drawn into length, (b), (c) a plurality of fiber bundles assembled therefrom again into a preform, which are drawn into length, and (d) assembled again, and (e) a plurality of fiber bundles fused under pressure to form a waveguide.

[0041] Fig. 5: Schematic cross-sections of (a), (c) fiber bundles being unrotated relative to one another, (b), (d) fiber bundles being rotated relative to one another.

[0042] Fig. 6: Schematic illustration of various further possibilities for fiber bundles having structural elements or cross-sectional regions thereof which are different, the waveguides each comprising a plurality of structural elements of a first type and a plurality of structural elements of a second type.

[0043] Fig. 7: Schematic illustration of various further possibilities for fiber bundles.

[0044] Fig. 8: Schematic illustration of various further possibilities for fiber bundles.

[0045] Fig. 9: Schematic illustration of various further possibilities for fiber bundles.

[0046] Fig. 10: Schematic illustration of various further possibilities for fiber bundles.

[0047] Fig. 11 : Schematic illustration of inventive glass optical fiber bundle 1.

[0048] Fig. 12: Schematic illustration of inventive glass optical fiber bundle 2.

[0049] Fig. 13: Schematic illustration of inventive glass optical fiber bundle 3. Fig. 14: Schematic illustration of inventive glass optical fiber bundle 4.

[0050] Fig. 15: Schematic illustration of inventive glass optical fiber bundle 5.

[0051] Figs. 16-19: Schematic illustrations of various glass optical fiber bundles.

[0052] Fig. 1 shows various examples of fiber bundles (1) which can be used as waveguides. The fiber bundles (1) shown in cross-section each comprise a plurality of structural elements (10), each of which extends along the direction of transport of the waveguide (100), which is perpendicular to Fig. 1, and each of which extends proportionally over the cross-section thereof. Each of the structural elements (10) thus defines a cross-sectional region (20), i.e. a proportion of the area of the cross-section of the fiber bundle (1). The examples of fiber bundles (1) shown in Fig. 1 each have at least two different types of structural elements, which differ in their refractive indices and / or diameters. These examples serve to illustrate some variants of non-uniformity.

[0053] The fiber bundle (1) shown in cross-section in Fig. 1 (a) has a first structural element 10a formed as a base body, which accommodates a plurality of second structural elements 10b. The second structural elements 10b may thereby be formed, for example, as cavities or hollow channels extending along the transport direction in the first structural element 10a. In this case, the first structural element 10a formed as a base body comprises a first material having a first refractive index, and the second structural elements 10b formed, for example, as cavities form the second refractive index, for example, by the air or another gas contained therein. In this case, the cross-sectional region 20 of the first structural element corresponds to the cross-sectional area of the fiber bundle (1) minus the holes in this area defined by the cavities, while the cross-sectional regions 20 of the second structural elements 10b each correspond to the cross-sectional area of the cavities. However, the cavities in the main body may also be filled with a second material, such that the second structural elements 10b correspond to the filled cavities. As schematically shown in Fig. 1 (a), the cross-sectional regions 20 of the second structural elements 10b are non-uniform in that their positions are non-uniformly distributed over the cross-section, in particular do not lie on a periodic grid.

[0054] The fiber bundle (1) shown in cross-section in Fig. 1 (b) has two types 10a, 10b of structural elements, namely one structural element 10a formed as a base body and having a first refractive index and a plurality of structural elements 10b having a second refractive index different therefrom. In the example shown in Fig. 1 (b), the cross-sectional regions 20 of the second structural elements 10b are not only non-uniformly arranged, but also have non-uniform geometries, in this case non-uniform diameters.

[0055] The fiber bundle (1) shown in cross-section in Fig. 1 (c) again has two types 10a, 10b of structural elements, wherein the cross-sectional regions of the second structural elements 10b are each arranged within a first structural element 10a as core-sheath systems. Thus, in this case, a plurality of first structural elements 10a and a plurality of second structural elements 10b are provided. The structural elements or their cross-sectional regions are formed non-uniformly in that the first structural elements 10a (which accommodate the second structural elements 10b) are arranged non-uniformly, in particular aperiodically, over the cross-section of the fiber bundle (1), and this distribution may be intentionally made.

[0056] The fiber bundles (1) shown in cross-section in Figs. 1 (d) and (e) correspond in some aspects to the fiber bundles (1) shown in Figs. 2(a) and (b), respectively, but having structural elements of three types 10a, 10b, 10c having different refractive indices. For example, cavities in the structural element 10a formed as a base body may be filled with different media. Accordingly, the structural elements 10b, 10c may have a non-uniformity in that their refractive index may differ from each other.

[0057] Fig. 2 shows two further examples of fiber bundles (1) which can be used as waveguides. The fiber bundles (1) in Fig. 2 comprise a plurality of first and second structural elements 10, each of which extends from a proximal end 2 to a distal end 4 of the fiber bundle (1) along the transport direction 5 and is, for example, rod-shaped. The fiber bundle (1) shown in Fig. 2(a) has a plurality of first structural elements 10a and a plurality of second structural elements 10b. The structural elements have a non- uniform arrangement in that the first structural elements 10a and the second structural elements 10b are non-uniformly arranged and / or distributed. The fiber bundle (1) shown in Fig. 2(b) comprises a plurality of structural elements 10, wherein in this example the cross-sectional regions of the structural elements have non-uniform geometries. For example, the geometries may differ in that the diameters of the structural elements or their cross-sectional regions differ from each other. Furthermore, the structural elements 10 in each of Figs. 2(a) and 2(b) may exhibit a non-uniformity in that the refractive indices of the structural elements differ from one another. In this respect, a discrete number of different refractive indices, for example two, three, four, etc. may be provided. Fig. 3 shows a cross-section of a fiber bundle (1) which corresponds in some aspects to the fiber bundle (1) shown in Fig. 2(a). The fiber bundle (1) shown in Fig. 3 has a plurality of rod-shaped structural elements 10, namely a plurality of a first structural elements 10a and a plurality of a second structural elements 10b, the structural elements 10 being arranged in cross-section on a hexagonal lattice composed of a plurality of smaller hex-packed bundles. At least one of the structural elements 10, or its cross-sectional area 20, may be equidistant from, and preferably adjacent to, six immediately adjacent structural elements 10, or their cross-sectional areas 20.

[0058] Fig. 4 shows steps of a method of manufacturing a waveguide according to a multi-draw method. In this method, a plurality of fiber bundles are assembled to form a preform 30 and drawn into length (Fig. 4a). The fiber bundles may be, for example, an arrangement of structural elements 10 or 10a,b or alternative arrangements for example according to those shown in Figs. 1 (a) to (e), which may be already drawn out in a known manner.

[0059] The assembled and elongated plurality of fiber bundles ("multi-fiber") may then be disassembled into sections and again assembled into a preform 40 (Fig. 4b, "multi-multi-assembly"). The preform 40 can then again be drawn to length (Fig. 4c), and if necessary again broken down into sections and assembled (Fig. 4d). The assembly thus obtained can be fused at the ends by applying heat and / or pressure and under vacuum (Fig. 4e).

[0060] With reference to Fig. 5, the assembled fiber bundles ("Multi-Fiber", here "M1") drawn to length can be assembled unrotated relative to one another (Fig. 5a) or rotated relative to one another (Fig. 5b) during assembly into a further preform. Furthermore, during the assembly, sections from at least two different assembled fiber bundles ("M1", "M2") drawn into length can be assembled unrotated (Fig. 5c) or rotated relative to one another (Fig. 5d). Analogous to the arrangements shown in Figs. 5a and 5b, the fiber bundles can also be or are arranged unrotated or rotated relative to one another when the first preform is assembled.

[0061] Fig. 6a shows a fiber bundle (1 ) having a plurality of structural elements 10a and a plurality of structural elements 10b having different refractive indices.

[0062] Fig. 6b shows a fiber bundle (1 ) having a plurality of structural elements 10d and a plurality of structural elements 10e, which have different refractive indices and a different substructure, the substructure being defined by sub-structural elements 10a and 10b (having refractive indices a and b) and 10a and 10c (having refractive indices a and c), respectively. The substructure here is that the structural elements 10d and 10e are formed as core-clad systems, with the cores being different from each other.

[0063] Fig. 6c shows a fiber bundle (1) having a plurality of structural elements 10d and a plurality of structural elements 10e, which have different refractive indices and a different substructure, the substructure being defined by the sub-structural elements 10a and 10b (having refractive indices a and b) and 10c and 10b (having refractive indices c and b), respectively. The substructure here is that the structural elements 10d and 10e are formed as core-cladding systems, with the claddings differing from each other.

[0064] Fig. 6d similarly shows a fiber bundle (1 ) having a plurality of structural elements 10e, a plurality of structural elements 10f, a plurality of structural elements 10g, and a plurality of structural elements 10h, which have different refractive indices and a different substructure, wherein the substructure is represented by the sub-structural elements 10a and 10b (having refractive indices a and b), resp. 10a and 10c (having refractive indices a and c) and 10b and 10d (having refractive indices b and d) and 10c and 10d (having refractive indices c and d), respectively. The substructure here is that the structural elements 10e, 10f, 10g and 10h are formed as core-shell systems, with both the shells and the cores being different.

[0065] Fig. 6e shows a fiber bundle (1 ) having a plurality of structural elements 10c and a plurality of structural elements 10d having different geometries and a different substructure, wherein the substructure of the structural element 10c is defined by the substructural elements 10a and 10b (having refractive indices a and b and a first core diameter), and the substructure of the structural element 10d is defined by the substructural elements 10a and 10b (having refractive indices a and b and a second core diameter).

[0066] Fig. 6f shows a fiber bundle (1) having a plurality of structural elements 10c and a plurality of structural elements 10d, which have different geometries and a different substructure, wherein the substructure of the structural element 10c is defined by the substructural elements 10a and 10b (having refractive indices a and b and a centrally positioned core), and the substructure of the structural element 10d is defined by the substructural elements 10a and 10b (having refractive indices a and b and an eccentrically positioned core). The structural elements of the first type 10a and of the second type 10b may be surrounded by a structural element of a third type 10c formed as a cladding tube. The cladding tube may have a refractive index which is lower than both the refractive index of the structural elements of the first type 10a and the refractive index of the second type 10b.

[0067] The fiber bundle (1) can comprise a plurality of first structural elements (10a) and a plurality of second structural elements (10b) and the waveguide (100) can comprise a single or a plurality of fiber bundles (1). The total number of first structural elements (10a) and second structural elements (10b) in the fiber bundle (1) can be enough to produce a centered polygonal unit, for example a fiber bundle having 20 to 300 structural elements or 50 to 300 structural elements, such as for example sixty one structural elements.

[0068] One or more of the first structural elements (10a) can be fused to one or more of the second structural elements (10b). The second structural element (10b) can be an air channel located within a matrix formed from the first structural element (10a). Each individual first structural element (10a) and each individual second structural element (10b) do not need to be surrounded by a cladding.

[0069] A plurality of the first structural elements (10a) and a plurality of the second structural elements (10b) can be distributed when viewed in a cross-section of the fiber bundle (1). The first structural element (10a) and the second structural element (10b) can have identical compositions but different diameters when viewed in a cross-section of the fiber bundle (1).

[0070] The optically active material may be considered to be a third structural element. For purposes of the current disclosure, an optically active material is a material that (1) converts one wavelength of an electromagnetic wave into another wavelength by any amount, such as converting x-rays to visible light, converting one wavelength of visible light to another wavelength of visible light, or converting visible light to infrared light, and / or (2) absorbs at least 50% of electromagnetic waves in the visible and / or infrared spectrum. The structural elements that are not intended to be optically active, such as the first and second structural elements, do not need to include an optically active material.

[0071] In some embodiments, the optically active material may comprise (i) a polymer comprising a dye, (ii) a glass comprising one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Pb, Bi, Cs, and I, or (iii) a combination thereof. The third structural element which may comprise the optically active material may comprise 10% or less, 5% or less, 3% or less, or 1 % or less of the total cross-sectional area of the fiber bundle. This low amount of optically active material provides more area for transmitting the electromagnetic waves.

[0072] When the optically active element is a solid material, the optically active material can be formed in the same manner and can have the same or a similar structure and material as the first structural elements or the second structural elements, for example the third structural element can be a fiber that extends along the transport direction. The third structural element can have a different longitudinal center axis than the first structural elements and the second structural elements as shown for example in Fig. 7.

[0073] The third structural elements may comprise an optically active material. The third structural elements comprising the optically active material may be a core fiber surrounded by a cladding to provide a coreclad third structural element comprising the optically active material. The cladding may be formed from the same or different material as the second structural element and may have a refractive index that differs from the refractive index of the second structural element by 0.1 or less. The closer the refractive index of the cladding is to the refractive index of the second structural element, the more likely the optically active material will selectively absorb electromagnetic waves without affecting transmission through the first structural element.

[0074] The third structural element may comprise a plurality of the core-clad third structural elements, and the plurality of the core-clad third structural elements may be surrounded by a cladding which may be formed from the same or different material as the second structural element and may have a refractive index that differs from the refractive index of the second structural element by 0.1 or less.

[0075] The distribution of the plurality of third structural elements may provide an adjacent factor of 40% or less, 39% or less, 38% or less, 37% or less, 36% or less, 35% or less, 34% or less, 33% or less, 32% or less, 31 % or less, or 30% or less, for the first structural elements. The distribution of the plurality of third structural elements may provide an extended adjacent factor of 60% or more, 65% or more, 70% or more, or 75% or more, for the second structural elements.

[0076] To determine the adjacent factor for the first structural elements, the structural elements adjacent to the third structural elements are counted. The counting procedure is described as follows. In a square-packed fiber bundle, the structural elements that are adjacent to the third structural element are the four structural elements directly north, directly east, directly south, and directly west of the third structural element. For example, in Fig. 7, the structural elements that are adjacent to the third structural element 33 (which is optically active material 33A in Fig. 7) are the four structural elements directly north, directly east, directly south, and directly west of the optically active material 33A, namely second structural element 32 directly north, first structural element 31 directly east, second structural element 32 directly south, and second structural element 32 directly west or the optically active material 33A. Thus, in the square-packed fiber bundle of Fig. 8 which depicts a total of seven third structural elements 33A and twenty-eight adjacent locations, Fig. 8 has nine first structural elements 31 in the twenty-eight adjacent locations. The adjacent factor for the first structural elements in Fig. 8 is therefore nine divided by twenty-eight which equals 32%. In other words, the adjacent factor for the first structural elements for a square-packed fiber bundle is:

[0077] Adjacent factor for first structural elements (square-pack) = total number of first structural elements adjacent to the third structural elements / (4 x total number of third structural elements)

[0078] In a hex-packed fiber bundle, the structural elements that are adjacent to the third structural element are the six structural elements that surround the third structural element. For example, in Fig. 9, the structural elements that are adjacent to the third structural element 33 (which is optically active material 33A in Fig. 9) are the are the six structural elements that surround the optically active material 33A, namely the two structural elements 31 and the four structural elements 32 shown in Fig. 9. Thus, in the hex-packed fiber bundle of Fig. 10 which depicts a total of one third structural element 33 and six adjacent locations, Fig. 10 has two first structural elements 31 in the six adjacent locations. The adjacent factor for the first structural elements in Fig. 10 is therefore two divided by six which equals 33%. In other words, the adjacent factor for the first structural elements for a hex-packed fiber bundle is:

[0079] Adjacent factor for first structural elements (hex-pack) = total number of first structural elements adjacent to the third structural elements / (6 x total number of third structural elements)

[0080] To determine the extended adjacent factor for the second structural elements, we count (1) the second structural elements adjacent to the third structural elements through one or more second structural elements and (2) the total number of second structural elements. For example, in the square-packed fiber bundle of Fig. 8, the structural second elements adjacent to the third structural elements through one or more second structural elements are the second structural elements encircled by the dashed lines. In Fig. 8, there are(1) fifty-one second structural elements 32 adjacent to the third structural elements 33 through one or more second structural elements 32 and (2) sixty-four second structural elements. The extended adjacent factor in Fig. 8 for the second structural elements is therefore fifty-one divided by sixty-four which equals 80%. In other words, the extended adjacent factor for the second structural elements for a square-packed fiber bundle is:

[0081] Extended adjacent factor for second structural elements (square-pack) = total number of second structural adjacent to the third structural elements through one or more second structural elements / total number of second structural elements

[0082] For example, in the hex-packed fiber bundle of Fig. 10, the structural second elements adjacent to the third structural elements through one or more second structural elements are the second structural elements encircled by the dashed lines. In Fig. 10, there are (1) twenty-six second structural elements 32 adjacent to the third structural elements 33 through one or more second structural elements 32 and (2) twenty-nine second structural elements. The extended adjacent factor in Fig. 10 for the second structural elements is therefore twenty-six divided by twenty-nine which equals 90%. In other words, the extended adjacent factor for the second structural elements for a hex-packed fiber bundle is:

[0083] Extended adjacent factor for second structural elements (hex-pack) = total number of second structural adjacent to the third structural elements through one or more second structural elements / total number of second structural elements

[0084] The current disclosure is not limited to the distribution or the amounts of the first, second, or third structural elements shown in Figs. 7-10.

[0085] The Michelson contrast is determined as follows.

[0086] The first step is image acquisition. One sample of the fiber bundle without the third structural element is obtained for reference. One or more samples of the fiber bundle with the third structural element, which can comprise an optically active material, are obtained for measurement. Starting with the reference sample, place a piece of metal foil to cover part of the entry facet with an optical diffuser on the metal foil, place the exit facet under a microscope, and take a picture containing both the shaded and the open areas. Use a microscope objective with a 20x magnification and a NA = 0.46. There should be no amplification, gain, or manual alteration applied to the detector setting. The value of white (average between red, blue and green values) should be between 160 and 180 on a scale between 0 and 255. Repeat the steps for the samples having the third structural element and match the value of white by solely changing the exposure value.

[0087] The second step is image analysis. At least ten single line scans of 1 pixel in height are made. The line scans should be parallel to either the horizonal or vertical edge of the image. The image must not be rotated, cropped or altered in any way. The line scans should be recorded in an area free of defects, blemishes or distortions. Each line scan is fitted to the following Error function: y=a+b*erf((x- c) / d). The fitted curves are plotted to determine the y-max and y-min values for each fitted curve. The average of all of the y-max values is taken and the average of all of the y-min values is taken. The Michelson contrast is: where Ymax is the average of all of the y-max values and Ymm is the average of all of the y-min values.

[0088] The waveguides can have a Michelson contrast at least 0.8, at least 0.81, at least 0.82, at least 0.83, at least 0.84, at least 0.85, at least 0.86, at least 0.87, at least 0.88, at least 0.89, at least 0.9, at least 0.91 , at least 0.92, at least 0.93, at least 0.94, or at least 0.95.

[0089] All of the ranges disclosed herein include all subranges and all combinations of the ranges and subranges.

[0090] The current disclosure relates to one or more of the following embodiments.

[0091] Embodiment 1 . A waveguide for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, comprising: a fiber bundle extending along the transport direction comprising: (a) a distribution of a plurality of first structural elements, (b) a distribution of a plurality of second structural elements that have a different refractive index from the first structural elements, such that the waveguide transmits electromagnetic waves along the transport direction according to the principle of transverse Anderson localization, and (c) a distribution of a plurality of third structural elements comprising an optically active material, wherein the distribution of the plurality of third structural elements provides an extended adjacent factor of 60% or more for the second structural elements.

[0092] Embodiment 2. A waveguide for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, comprising: a fiber bundle extending along the transport direction comprising: (a) a distribution of a plurality of first structural elements, (b) a distribution of a plurality of second structural elements that have a different refractive index from the first structural elements, such that the waveguide transmits electromagnetic waves along the transport direction according to the principle of transverse Anderson localization, and (c) a distribution of a plurality of third structural elements comprising an optically active material, wherein the optically active material extends along the transport direction and having a different longitudinal center axis than the first structural elements and the second structural elements.

[0093] Embodiment 3. A waveguide for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, comprising a fiber bundle extending along the transport direction comprising: (a) a distribution of a plurality of first structural elements, (b) a distribution of a plurality of second structural elements that have a different refractive index from the first structural elements, such that the waveguide transmits electromagnetic waves along the transport direction according to the principle of transverse Anderson localization, and wherein the waveguide has a Michelson contrast at least 0.8.

[0094] Embodiment 4. The waveguide of one or more of the preceding embodiments, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 40% or less for the first structural elements.

[0095] Embodiment 5. The waveguide of one or more of the preceding claims, wherein the optically active material comprises 10% or less of a total cross-sectional area of the fiber bundle.

[0096] Embodiment 6. The waveguide of one or more of the preceding embodiments, wherein the optically active material extends along the transport direction and having a different longitudinal center axis than the first structural elements and the second structural elements. Embodiment 7. The waveguide of one or more of the preceding embodiments, wherein the waveguide comprises a plurality of fiber bundles.

[0097] Embodiment 8. The waveguide of one or more of the preceding embodiments, wherein the optically active material comprises (i) a polymer comprising a dye, (ii) a glass comprising one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Pb, Bi, Cs, and I, or (iii) a combination thereof.

[0098] Embodiment 9. The waveguide of one or more of the preceding embodiments, wherein the optically active material comprises less than 3% or less of the total cross-sectional area of the fiber bundle.

[0099] Embodiment 10. The waveguide of one or more of the preceding embodiments, wherein the third structural element comprises an optically active material that is a core fiber surrounded by a cladding comprises to provide a core-clad third structural element comprising the optically active material, the cladding having a refractive index that differs from a refractive index of the second structural element by 0.1 or less.

[0100] Embodiment 11 . The waveguide of one or more of the preceding embodiments, wherein the third structural element comprises a plurality of the core-clad third structural elements, the cladding having a refractive index that differs from a refractive index of the second structural element by 0.1 or less.

[0101] Embodiment 12. The waveguide of one or more of the preceding embodiments, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 35% or less for the first structural elements, and the distribution of the plurality of third structural elements provides an extended adjacent factor of 70% or more for the second structural elements.

[0102] Embodiment 13. The waveguide of one or more of the preceding embodiments, wherein the Michelson contrast is at least 0.85.

[0103] Embodiment 14. The waveguide according to one or more of the preceding embodiments, wherein the waveguide is a rigid image guide or an at least partially flexible image guide used as a component in a medical device for an endoscope or as an x-ray imaging faceplate, as an image modifying optical component or as a fiber optical component such as a (resizing) taper or an image inverter for example used in a night vision device, as a component for spatial multiplexing for data communication, as a component in remote optical sensing, as a component in a lighting application, and as an energy relay for a light field energy system.

[0104] Examples:

[0105] Example 1 :

[0106] A comparative glass optical fiber bundle 1 was prepared in the same manner as Example 1 of commonly owned WO 2023 / 118368, with some minor revisions. Namely, a 25 mm thick glass optical fiber bundle where the majority of light is transmitted via Anderson localization instead of traditional total internal reflection was prepared as follows. Two types of glass rods (monos) with the same diameter, but a refractive index difference of 0.23 were arranged in a -50:50 mixture in a square-pack multi configuration in a predetermined fashion, as disclosed herein, and drawn to a fiber bundle. In a second drawing step, a plurality of these multi fibers is assembled in multi-multi arrangement, where the multi fibers were configuration in a predetermined fashion, as disclosed herein. Additional drawing steps in the same manner were applied, until the diameter of the mono fiber was reduced to a size of 700-800 nm.

[0107] Inventive glass optical fiber bundles 1-5 were manufactured in the same manner as comparative bundle 1 , except that a black glass capable of absorbing more than 50% of the electromagnetic waves through the material was added to the distribution as a third structural element in a predetermined fashion to get inventive examples 1-5. The resulting distribution of the first, second, and third structural elements is shown in Fig. 11 having 0.05% of the third structural element, Fig. 12 having 0.15% of the third structural element, Fig. 13 having 0.25% of the third structural element, Fig. 14 having 0.34% of the third structural element, and Fig. 15 having 0.49% of the third structural element.

[0108] The Michelson contract of comparative glass optical fiber bundle 1 and inventive glass optical fiber bundles 1-5 were measured as described herein. The values are shown in the following Table 1. TABLE 1

[0109] Figs. 16-19 show additional possible distributions of structural elements. The resulting data is shown in the following Table 2.

[0110] TABLE 2

Claims

Claims1 . A waveguide for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, comprising: a fiber bundle extending along the transport direction comprising:(a) a distribution of a plurality of first structural elements,(b) a distribution of a plurality of second structural elements that have a different refractive index from the first structural elements, such that the waveguide transmits electromagnetic waves along the transport direction according to the principle of transverse Anderson localization, and(c) a distribution of a plurality of third structural elements comprising an optically active material, wherein the distribution of the plurality of third structural elements provides an extended adjacent factor of 60% or more for the second structural elements.

2. The waveguide of the preceding claim, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 40% or less for the first structural elements.

3. The waveguide of one or more of the preceding claims, wherein the optically active material comprises 10% or less of a total cross-sectional area of the fiber bundle.

4. The waveguide of one or more of the preceding claims, wherein the optically active material extends along the transport direction and has a different longitudinal center axis than the first structural elements and the second structural elements.

5. The waveguide of one or more of the preceding claims, wherein the waveguide comprises a plurality of fiber bundles.

6. The waveguide of one or more of the preceding claims, wherein the optically active material comprises (i) a polymer comprising a dye, (ii) a glass comprising one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Pb, Bi, Cs, and I, or (iii) a combination thereof.

7. The waveguide of one or more of the preceding claims, wherein the optically active material comprises less than 3% or less of the total cross-sectional area of the fiber bundle.

8. The waveguide of one or more of the preceding claims, wherein the third structural element comprises an optically active material that is a core fiber surrounded by a cladding to provide a coreclad third structural element comprising the optically active material, the cladding having a refractive index that differs from a refractive index of the second structural element by 0.1 or less.

9. The waveguide of one or more of the preceding claims, wherein the third structural element comprises a plurality of the core-clad third structural elements, the cladding having a refractive index that differs from a refractive index of the second structural element by 0.1 or less.

10. The waveguide of one or more of the preceding claims, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 35% or less for the first structural elements, and the distribution of the plurality of third structural elements provides an extended adjacent factor of 70% or more for the second structural elements.11 . The waveguide of one or more of the preceding claims, wherein the Michelson contrast is at least 0.85.

12. The waveguide of one or more of the preceding claims, wherein the waveguide is a rigid image guide or an at least partially flexible image guide used as a component in a medical device for an endoscope or as an x-ray imaging faceplate, as an image modifying optical component or as a fiber optical component such as a (resizing) taper or an image inverter for example used in a night vision device, as a component for spatial multiplexing for data communication, as a component in remote optical sensing, as a component in a lighting application, and as an energy relay for a light field energy system.

13. A waveguide for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, comprising: a fiber bundle extending along the transport direction comprising:(a) a distribution of a plurality of first structural elements,(b) a distribution of a plurality of second structural elements that have a different refractive index from the first structural elements, such that the waveguide transmits electromagnetic waves along the transport direction according to the principle of transverse Anderson localization, and(c) a distribution of a plurality of third structural elements comprising an optically active material, wherein the optically active material extends along the transport direction and has a different longitudinal center axis than the first structural elements and the second structural elements.

14. The waveguide of claim 13, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 40% or less for the first structural elements.

15. The waveguide of one or more of claims 13-14, wherein the optically active material comprises 10% or less of a total cross-sectional area of the fiber bundle.

16. The waveguide of one or more of claims 13-15, wherein the waveguide comprises a plurality of fiber bundles.

17. The waveguide of one or more of claims 13-16, wherein the optically active material comprises (i) a polymer comprising a dye, (ii) a glass comprising one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Pb, Bi, Cs, and I, or (iii) a combination thereof.

18. The waveguide of one or more of claims 13-17, wherein the optically active material comprises less than 3% or less of the total cross-sectional area of the fiber bundle.

19. The waveguide of one or more of claims 13-18, wherein the third structural element comprises an optically active material that is a core fiber surrounded by a cladding to provide a core-clad third structural element comprising the optically active material, the cladding having a refractive index that differs from a refractive index of the second structural element by 0.1 or less.

20. The waveguide of one or more of claims 13-19, wherein the third structural element comprises a plurality of the core-clad third structural elements, the cladding having a refractive index that differs from a refractive index of the second structural element by 0.1 or less.21 . The waveguide of one or more of claims 13-20, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 35% or less for the first structural elements, and the distribution of the plurality of third structural elements provides an extended adjacent factor of 70% or more for the second structural elements.

22. The waveguide of one or more of claims 13-21 , wherein the Michelson contrast is at least 0.85.

23. The waveguide of one or more of claims 13-22, wherein the waveguide is a rigid image guide or an at least partially flexible image guide used as a component in a medical device for an endoscope or as an x-ray imaging faceplate, as an image modifying optical component or as a fiber optical component such as a (resizing) taper or an image inverter for example used in a night vision device, as a component for spatial multiplexing for data communication, as a component in remote optical sensing, as a component in a lighting application, and as an energy relay for a light field energy system.

24. A waveguide for transmitting electromagnetic waves from a proximal end of the waveguide to a distal end of the waveguide along a transport direction extending between the proximal and distal ends, comprising a fiber bundle extending along the transport direction comprising:(a) a distribution of a plurality of first structural elements,(b) a distribution of a plurality of second structural elements that have a different refractive index from the first structural elements, such that the waveguide transmits electromagnetic waves along the transport direction according to the principle of transverse Anderson localization, and wherein the waveguide has a Michelson contrast at least 0.8.

25. The waveguide of claim 24, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 40% or less for the first structural elements.

26. The waveguide of one or more of claims 24-25, wherein the optically active material comprises 10% or less of a total cross-sectional area of the fiber bundle.

27. The waveguide of one or more of claims 24-26, wherein the optically active material extends along the transport direction and has a different longitudinal center axis than the first structural elements and the second structural elements.

28. The waveguide of one or more of claims 24-27, wherein the waveguide comprises a plurality of fiber bundles.

29. The waveguide of one or more of claims 24-28, wherein the optically active material comprises (i) a polymer comprising a dye, (ii) a glass comprising one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, W, Pb, Bi, Cs, and I, or (iii) a combination thereof.

30. The waveguide of one or more of claims 24-29, wherein the optically active material comprises less than 3% or less of the total cross-sectional area of the fiber bundle.31 . The waveguide of one or more of claims 24-30, wherein the third structural element comprises an optically active material that is a core fiber surrounded by a cladding to provide a core-clad third structural element comprising the optically active material, the cladding having a refractive index that differs from a refractive index of the second structural element by 0.1 or less.

32. The waveguide of one or more of claims 24-31 , wherein the third structural element comprises a plurality of the core-clad third structural elements, the cladding having a refractive index that differs from a refractive index of the second structural element by 0.1 or less.

33. The waveguide of one or more of claims 24-32, wherein the distribution of the plurality of third structural elements provides an adjacent factor of 35% or less for the first structural elements, and the distribution of the plurality of third structural elements provides an extended adjacent factor of 70% or more for the second structural elements.

34. The waveguide of one or more of claims 24-33, wherein the Michelson contrast is at least 0.85.

35. The waveguide of one or more of claims 24-34, wherein the waveguide is a rigid image guide or an at least partially flexible image guide used as a component in a medical device for an endoscope or as an x-ray imaging faceplate, as an image modifying optical component or as a fiber optical component such as a (resizing) taper or an image inverter for example used in a night vision device, as a component for spatial multiplexing for data communication, as a component in remote optical sensing, as a component in a lighting application, and as an energy relay for a light field energy system.

Images