LIGHT CONCENTRATOR

Description

[0001] The invention relates to a light concentrator comprising at least one waveguide, preferably comprising a layered, in particular Z-direction layered, stack of at least two waveguides, wherein the at least one waveguide has a light-deflectoring structure between two layer arrangements of at least two transparent dielectric layers layered in a layering direction, with which light incident on the at least one waveguide of at least one predetermined wavelength range can be directed into the waveguide, wherein at least one mode of the at least one predetermined wavelength range can be guided in the waveguide by total internal reflection, which, viewed in the layering direction, has at least one, preferably exactly one, local intensity minimum in its intensity distribution, which is arranged within the light-deflectoring structure.

[0002] A light concentrator of the type mentioned above is known, for example, from publication EP 3 164 744 A1 of the same applicant.

[0003] Such a light concentrator is also known from publication EP 2 061 092 A1.

[0004] The following description of a light concentrator or waveguide preferably also applies to the invention described later.

[0005] A light concentrator according to the invention can have a single waveguide of the aforementioned design, but preferably also a stack of at least two waveguides stacked in a stacking direction, particularly wherein the stacking direction is parallel to the layering direction. The following descriptions apply both to a single waveguide and to each of several stacked waveguides of a light concentrator according to the invention.

[0006] For a better understanding of the invention, it can be assumed that the layers of the layer arrangements are stacked in a referenced coordinate system in its Z-direction. Similarly, any stacked waveguides are stacked in the Z-direction. The at least two layers of the respective layer arrangement are then preferably arranged parallel to a plane perpendicular to Z, e.g., parallel to an XY plane of a Cartesian coordinate system or parallel to a plane spanned by ρ and φ of a cylindrical coordinate system. The respective entire layer arrangements are thus extended in the same direction.

[0007] In a waveguide, it is provided that light incident on an outer layer of one of the layer arrangements and transmitted through this (first) layer arrangement can be directed into the waveguide by the light-deflectoring structure. Preferably, this applies at least to light arriving from at least one predetermined direction, or with a predetermined angle of incidence between the Z-axis and the direction of incidence. θ ein Light falls onto the waveguide or the outer surface of its outermost layer in a layered array and is transmitted to the light-deflectoring structure. Such a predetermined direction can, for example, be perpendicular to the surface of the outermost layer of a layered array, i.e., parallel to the Z-direction. Such a perpendicular direction of incidence is accordingly defined by θ ein= 0 is characterized. Furthermore, this applies at least to light of at least one predetermined wavelength, in particular a predetermined wavelength range.

[0008] This preferably means that the deflection of the incident light with this predetermined wavelength or wavelength range occurs in the direction of the possible propagation direction(s) of a mode guided in the waveguide with a propagation constant β of this wavelength or wavelength range, i.e., in particular, that the change in angle Δ θ through the distraction the relationship β = 2 π λ ⋅ n i ⋅ sin θ ein + P θ ein λ mit P θ ein λ = 2 π λ sin Δ θ θ ein fulfilled.

[0009] With reference to the aforementioned assumed coordinate system, the light of a dielectric mode in the waveguide is preferably guided in all directions perpendicular to the Z-direction or, more generally, perpendicular to the layering direction of the layers and / or the stacking direction of any stacked waveguides. This direction in which the mode is guided is also referred to as lateral, whereas the Z-direction or the layering direction is referred to as normal.

[0010] Within the respective waveguide, the light, in particular the guided mode, is guided at / in the two layer arrangements parallel to the layers by the principle of total internal reflection.

[0011] In particular, in stepwise transitions of the refractive index, the light is reflected back by total internal reflection into the inner region of the waveguide, which has the higher refractive index and in which the mode is guided, at two planes defined by such transitions which are arranged around the light-deflectoring structure, in particular in one of the layer arrangements arranged on both sides of the light-deflectoring structure.

[0012] This outer area has a lower refractive index.

[0013] In the case of a gradual transition of the refractive index, total internal reflection can also occur in a distributed manner, i.e., not at a definable plane, but distributed within an area bounded by planes.

[0014] The respective transition between the inner and one of the two outer regions is characterized by a continuous or stepwise decrease in the refractive index, so that the mode is guided in the higher refractive index inner region and is totally reflected in this transition to an outer region of lower refractive index, with this region of lower refractive index representing the outer region where the mode decays evanescently.

[0015] The mode formed by total reflection propagates laterally.

[0016] The layers of the layer arrangements are preferably selected with respect to the transparent material of the layers (in particular with respect to the refractive index) and thickness of the respective layer (considered in the layering direction / Z-direction), e.g. by calculation carried out before the manufacture of the waveguide, such that in the waveguide formed by the layer arrangements at least one mode of the predetermined wavelength range or the predetermined wavelength(s) can be guided laterally by total internal reflection, which in its intensity distribution considered perpendicular to the guidance direction, i.e. in the layering direction or Z-direction, has at least one, preferably exactly one, local intensity minimum which is located within the light-deflectoring structure (considered in the layering direction or Z-direction).Z-direction), preferably wherein the local maxima of the intensity distribution surrounding the local minimum are located around the light-deflectoring structure, i.e., outside of it, and in particular within the respective layer arrangement. A predetermined wavelength is thus preferably both one for which the light-deflectoring structure performs a deflection into the waveguide and one with which a guided mode with an intensity minimum positioned appropriately to the light-deflectoring structure is generated in the waveguide.

[0017] With a constructively adapted selection of waveguide layers and position of the light-deflectoring structure in the waveguide, the light-deflectoring structure can be configured to excite a mode propagating in the waveguide from the incident light of the predetermined wavelength(s), which, viewed in the Z direction, has at least one local intensity minimum located in the light-deflectoring structure and preferably has local intensity maxima arranged around the outside of the structure.

[0018] This ensures that the majority of the mode's intensity is guided outside the light-deflectoring structure within the waveguide. Losses caused by the light-deflectoring structure are thus minimized. A light-deflectoring structure arranged in this way can therefore couple incident light into the waveguide over a relatively large area relative to the propagation direction of the excited mode, since this excited mode exhibits a long propagation length due to the small overlap with the light-deflectoring structure. Preferably, the local minimum of the guided mode's intensity lies within the light-deflectoring structure in the Z-direction, or the layering direction.

[0019] The arrangement of the local intensity minimum within the light-deflecting structure is preferably understood to mean that, relative to the assumed Z-axis of a coordinate system parallel to the layering direction, the intensity minimum is located at a coordinate Zmin that lies within the coordinate interval over which the light-deflecting structure extends in the direction of the Z-axis. The coordinates Zmax1 and Zmax2 of two intensity maxima arranged around the considered local minimum lie outside this interval. For example, if the light-deflecting structure extends in the Z-direction within a coordinate interval from Z1 to Z2, then: Zmax1 < Z1 < Zmin < Z2 < Zmax2.

[0020] In a further preferred embodiment of the invention, the waveguide can be symmetrically structured with respect to its layer arrangements. In particular, this means that the layers of both layer arrangements surrounding the light-deflectoring structure are symmetrically structured with respect to a central plane, preferably around which the light-deflectoring structure is also arranged, with respect to thickness and refractive index, and in particular mirror-symmetrically structured.

[0021] A symmetrical arrangement has the advantage of a position in the Z-direction of the local minimum intensity that is largely independent of the wavelength. The principle of deflection and mode generation can thus be achieved for a wider wavelength range compared to a non-symmetrical arrangement.

[0022] In the light concentrator described in the aforementioned publication, the light-deflectoring structure is described as a nanostructured layer whose structures are smaller than the wavelength of a mode guided in the waveguide. The deflection of the light into the waveguide therefore occurs, for example, through diffraction, i.e., a higher-order interaction, and thus with reduced efficiency, since zero-order light experiences no deflection into the waveguide.

[0023] The object of the invention is to provide a light concentrator of the type mentioned above that achieves increased efficiency and reduced dispersion with respect to coupling in and out, preferably by zero-order light deflection, for example according to the principles of geometric optics, e.g. by reflection or refraction. The power loss due to diffraction at the light-deflectoring structure should be significantly reduced.

[0024] This problem is solved by the fact that the light-deflectoring structure has one or more light guides arranged side by side perpendicular to the layering direction, wherein each light guide has facets, in particular facets formed by regions of different refractive indices, each of which is larger than the longest wavelength of the predetermined wavelength range in each of three mutually perpendicular spatial directions and with which the incident light can be deflected towards a light-collecting region assigned to the respective light guide, wherein a facet is formed by an interface between two dielectric media with different refractive indices, wherein at both transitions between the inner region and the outer region of the layer arrangements, where total internal reflections are thereby enabled,that at each transition there is a stepwise or spatially distributed transition from the higher refractive index in the inner region to a refractive index reduced by a refractive index difference in the outer region, and where this refractive index difference is less than 1x10 -3< .,

[0025] This allows light to be concentrated from the light-collecting surface of the structure.

[0026] Preferably, the light can also be deflected by the facets in the direction of an output element, in particular which is not part of the light guides, but preferably which is offset in the Z direction, especially above or below the light collecting area and / or light guide.

[0027] According to the invention, a facet is formed by an interface between two dielectric media with different refractive indices. More preferably, the facet or interface can be formed in a cross-sectional plane encompassing the Z-axis, preferably linearly extended, but in particular also curved.

[0028] Furthermore, according to the invention, at both transitions between the inner region and the outer region, in particular those arranged in the Z-direction on both sides of the light guides in the respective layer arrangements where total reflections take place, a stepwise or spatially distributed transition from the higher refractive index in the inner region to a refractive index reduced by a refractive index difference in the outer region takes place, and wherein this refractive index difference is less than 1x10 -3< , more preferably less than 1x10 -4< , and even more preferably less than 1x10 -5< .

[0029] For example, in any layer arrangement of layers of the waveguide adjacent to a light guide, the refractive index, in particular the refractive index averaged over the layer thickness of a layer further away from the light guide, can be lower than the refractive index of a closer layer, wherein the refractive index difference of the adjacent layers of a layer arrangement is less than 1x10 -3< , more preferably less than 1x10 -4< .

[0030] In all cases, the refractive index difference can preferably be smaller than a single value. nor - on , which the condition M = 1 + int 2 V / π mit V = 2 πt i n i / λ n i 2 − n a 2 fulfilled, whereby nor the average refractive index of the inner area and on the average refractive index of the part of the outer region relevant for wave guidance, which is therefore in the direction z no further than you / 2 away from the inner area λthe wavelength and you the thickness of the inner area of ​​the layer arrangement.

[0031] Compared to the prior art cited above, the invention has the advantage that, due to the formation of the facets of a light guide, preferably formed by regions of different refractive indices and larger than the at least one predetermined wavelength, deflection and mode generation occur for this at least one wavelength, wherein the deflection is based at least predominantly on the principles of geometric optics, i.e., for example, by reflection or refraction. Deflection in the waveguide by diffraction either does not occur or at least does not constitute the predominant deflection principle and is therefore, in particular, negligible.

[0032] Due to the formation of facets that are larger, preferably larger in three mutually perpendicular spatial directions than the at least one predetermined wavelength, each light guide, and in particular the entire light-deflectoring structure, preferably also has an extent in the aforementioned layering direction, especially the aforementioned Z-direction of an assumed coordinate system, that is larger than the predetermined wavelength. The predetermined wavelength can be a wavelength from a wavelength range that can be propagated in the waveguide, e.g., the mean wavelength of this range or also the maximum wavelength of this range.

[0033] In comparison to the aforementioned prior art, each facet of a light guide, and thus of the light-deflectoring structure, has a macroscopic form, in particular with a size in each of the three spatial directions of nx λ, where λ corresponds to the predetermined wavelength of the light, and furthermore, the following applies: n ≥ 1 is, preferably n ≥ 2 is, further preferred n ≥ 3 is even more preferred n ≥ 4 is even more preferred n ≥ 10.

[0034] In absolute terms, the size of a facet in the layering direction (Z-direction) and / or in each of the three spatial directions is more than 900 nm, more preferably more than 1800 nm, even more preferably more than 2700 nm, even more preferably more than 3600 nm, even more preferably more than 9 micrometers.

[0035] Preferably, the thickness of the waveguide with the two layer arrangements surrounding the light-deflectoring structure can be greater overall than mx λ, where λ corresponds to the predetermined wavelength of the light and m>10, preferably m > 20, more preferably m > 100, more preferably m > 200.

[0036] The light guides can, in principle, be arranged side by side. In such an arrangement of several light guides, they lie next to each other in a plane that is perpendicular to the layering direction, i.e., parallel to the XY plane of a Cartesian coordinate system or parallel to a plane spanned by ρ and φ of a cylindrical coordinate system.

[0037] The decreasing refractive index in the layers of the two layer arrangements, as viewed from a light guide, causes the guided light mode to be guided in the waveguide by the principle of total internal reflection. The small differences in the refractive indices of adjacent layers result in minimal mode guidance.

[0038] This allows for a reduction in the number of possible modes in the waveguide compared to the aforementioned prior art. In particular, it ensures that, despite the large extent of the light-deflecting structure in the layering direction, especially the layer arrangements, and preferably thus of the entire waveguide in the Z-direction, the number of guided modes is not increased compared to the prior art. This allows for the generation of an increased intensity profile in the Z-direction compared to the prior art, the intensity minimum of which effectively minimizes the overlap of the mode with the light-deflecting structure, particularly when the intensity conditions specified below are met.

[0039] The aforementioned small differences in the refractive indices of adjacent layers of a layer arrangement or between the inner region and the outer region of the layer arrangements can, in a preferred embodiment, be achieved by different doping of the same host material, in particular polymer, from which a respective layer of the layer arrangement or of the two regions is formed.

[0040] A layer arrangement of at least two layers is understood not only to mean that the at least two layers are adjacent to each other via a discrete boundary layer where a sudden change in material and / or refractive index takes place, but also that it includes at least two material regions of different material and / or different refractive index extending perpendicular to the layering direction in the plane, between which there is a boundary region extending in the layering direction in which the material and / or the refractive index changes continuously.

[0041] Despite such a large design, the facets of each light guide can lie in a direction perpendicular to the layering direction and thus in a direction parallel to the propagation direction of at least one guided mode, or laterally one behind the other, and couple incident light into the waveguide without significant shading by other facets lying in the propagation path of the mode, because the light-deflectoring structure, and thus also each light guide and thus each facet, lies according to the invention in the local intensity minimum of the generated guided mode, since the position, in particular the Z-position, of the light-deflectoring structure / light guide is positioned by the design of the waveguide such that it lies on the light-deflectoring structure / light guide for the predetermined wavelength(s) in the layering direction or Z-direction.The invention thus circumvents the usual shadowing problems of geometric optics.

[0042] In a preferred embodiment, the light-deflectoring structure, and thus the light guide, or each light guide and each layer arrangement, has an extension in the layering direction or Z-direction of the waveguide, such that the light-deflectoring structure / the light guide lies in regions smaller than I max / m with respect to a local maximum I max of intensity located next to the local minimum, with m greater than 10, preferably m greater than 50, more preferably m greater than 100, even more preferably m greater than 250, even more preferably m greater than 1000.

[0043] The at least one predetermined wavelength preferably lies in the range of 300 to 2500 nm and thus in the sunlight spectrum, more preferably in the range of 400 to 900 nm. This wavelength range thus preferably constitutes the predetermined wavelength range mentioned above. In this way, the device according to the invention can preferably be used to concentrate sunlight, e.g., onto a solar cell.

[0044] The light guide need not consist of an accumulation of solid material, although it may include or be made of such material.

[0045] In particular, the term should also encompass the fact that the light guide represents an arrangement of a medium, which can also be a liquid, a gas or gas mixture, or even a vacuum. A light guide can thus also be formed by one or more bodies within the waveguide, especially in at least one of the inner layers, which can consist of any medium or can be unfilled (evacuated). Possible solid materials for a light guide include transparent oxides, nitrides, salts, other inorganic or organic compounds, transparent polymers, and other transparent materials. A medium can also be formed by a gas or gas mixture.

[0046] Preferably, the inner layers, or the inner region of the waveguide, are understood to be those layers that are directly adjacent to or encompass the light guides. The layers of the outer region lie around them. Preferably, the boundary between the inner and outer regions is determined by the locations where light of the mode propagating in the waveguide is guided by total internal reflection.

[0047] Overall, the inventive design of a light concentrator thus enables light incident on the waveguide to be coupled into the waveguide in a predominantly zero-order manner by interaction with the light-deflectoring structure or a light guide, in particular, for example, by reflection or refraction, and concentrated in the direction of the light-collecting area, wherein the light-deflectoring structure or the light guide is located at the minimum of the at least one, in particular exactly one, guided mode, or, in the case of several guided modes per (predetermined) wavelength, at the intensity minimum of all guided modes, or conversely, the intensity minimum of a respective guided mode with respect to the Z-direction lies within the light-deflectoring structure or the light guide.

[0048] It is important to consider that the position of the intensity minimum or minima of a guided mode is not determined by the existence of the light-deflecting structure or light guide, but rather that the position of the intensity minimum or minima of a guided mode is determined, and in particular is determined at least primarily, by the superimposed layers of the two layer arrangements surrounding the light-deflecting structure / light guide in the layering direction. If anything, the position is only minimally influenced by the light-deflecting structure / light guide.

[0049] The position of the light-deflectoring structure / light guide and the at least one intensity minimum can thus be determined beforehand, e.g. by calculation, in particular depending on at least the layer parameters (e.g. refractive index, thickness) and the waveguide can be manufactured such that the intensity minimum of the at least one guided mode lies on the light-deflectoring structure or on the light guide according to the invention.

[0050] The light-collecting region is a region of the light guide, preferably a region bounded in the X and Y directions, towards which the mode guided in the waveguide propagates, in particular from at least one direction, preferably from several directions. Most preferably, the guided mode propagates in the waveguide to the light-collecting region from at least two opposite directions, preferably from a plurality of opposite directions. Thus, the light-collecting region is the region of the light guide with the highest intensity, even though it spatially coincides with the position of the intensity minimum as viewed in the Z direction, while the intensity maximum of the guided mode is offset relative to the light guide in the Z direction. Preferably, the light-collecting region is a region of the light guide around which the facets of the light guide are arranged.

[0051] The light-collecting area can be formed, for example, by an area, in particular by an area limited in a radial direction around the Z-axis, especially of the light guide, around which the facets of the light guide are arranged.

[0052] Preferably, a coupling element can be provided in the waveguide with which light can be deflected in the direction of an arrangement to be illuminated, e.g. in the direction of an arrangement to be illuminated, in particular a solar cell which is arranged in the waveguide or in the Z-direction adjacent to the waveguide.

[0053] Preferably, the decoupling element is located above or below the light-collecting area and / or light guide when viewed in the Z-direction; however, it is particularly important that it does not form part of the light-deflecting structure / light guide, but is independent of it. Furthermore, the decoupling element is preferably arranged around the Z-axis, especially if the facets are used to propagate the mode from multiple directions towards the Z-axis.

[0054] A preferred embodiment of the invention may provide that, in the layering direction below or above the coupling element, a solar cell is arranged in a layer or on the surface of a layer of the waveguide, which is illuminated by light emerging from the coupling element, in particular scattered or reflected light.

[0055] This allows the concentrated light within the arrangement to be used, for example, to convert it into electrical energy using a solar cell. In this case, a reflective coating can be arranged in a layer or on the surface of a layer of the at least one waveguide on the side of the light-deflectoring structure facing away from the arrangement / solar cell, particularly one that is concave in the direction of the arrangement / solar cell. This allows light that is not directly scattered towards the arrangement / solar cell to be reflected back towards the arrangement / solar cell by means of the reflective coating.

[0056] The coupling element can, for example, be designed as a material recess in the light-deflecting structure and / or at least one of the waveguide layers. Such a material recess can preferably be gas-filled or evacuated. This ensures that the coupling element is not damaged even at high intensities.

[0057] The output coupling element can, in particular, comprise a reflective, preferably totally reflective, arrangement, especially of interfaces between different materials and / or refractive indices, with which light can be deflected from the direction of a mode propagating in the waveguide. The deflection can preferably be in the direction of a aforementioned solar cell.

[0058] A preferred embodiment provides that the output coupling element, viewed in the layering direction, is arranged above or below the light guide at the location of at least one of the intensity maxima surrounding the local intensity minimum. This places the output coupling element offset in the layering direction relative to the light-deflectoring structure or the light guide, in particular offset by the distance between the intensity minimum and an adjacent intensity maximum of the guided mode. Viewed in the propagation direction of the mode, an intensity maximum of the mode thus lies on the output coupling element.

[0059] In principle, the invention can provide that the facets of a light guide are arranged in only two opposite directions, i.e., at 180 degrees around a strip-shaped light-collecting area. Thus, the light is concentrated onto a strip-shaped area; concentration within the waveguide therefore occurs in only one dimension.

[0060] A preferred embodiment, however, provides that each facet of a light guide of the light-deflectoring structure surrounds the light-collecting area at least partially in a frame-like manner, preferably forming a closed frame, and more preferably at least partially in an annular manner, particularly forming a closed ring. This ensures that light incident on the waveguide from multiple locations surrounding a light-collecting area is deflected, preferably in a frame-like or annular manner, by a respective facet towards this light-collecting area. Thus, the light is guided onto a circular light-collecting area and accordingly focused in two dimensions within the waveguide.

[0061] The light-collecting area for such a design can be defined as the area of ​​the light guide that is located within a maximum distance ρ 0 from the geometric center of the respective light guide.

[0062] Each light guide can, in particular to generate a reflective deflection in zero order, have at least one reflective or totally reflective facet, preferably several reflective or totally reflective facets arranged one behind the other perpendicular to the Z direction or parallel to the mean propagation direction of the mode.

[0063] For example, in the case of a (total) reflective design, each facet can form a surface inclined from the XY plane in the direction of the Z-axis or to an imaginary cylinder around the Z-axis.

[0064] To create a deflection by light refraction in transmission, each light guide can have at least one group, preferably several groups, of at least two interacting facets at which transmitted light is refracted to perform the deflection. Each facet can be formed by an interface between two media with different refractive indices.

[0065] A particularly preferred embodiment of the invention provides that, assuming the origin of a cylindrical coordinate system, each light guide of a light-deflectoring structure has at least one, preferably several, reflective or refractive facets arranged one behind the other perpendicular to the Z-direction or parallel to the mean propagation direction of the mode, at least partially surrounding the Z-axis, preferably circumferentially. It is further preferred that the normal vector projected into the ρ-φ plane has a φ component of zero for every location on each facet of the light guide, except at its edge. This means that the projection of the normal vector of each facet either points exactly to this center point or exactly away from it, so that the vector multiplied by -1 points exactly to the center point.

[0066] The facets of a light guide of a light-deflectoring structure (all or at least some of these, preferably at least those located near the center) can, in a further preferred embodiment, be rotationally symmetrical around a center point in the light-collecting area or around the Z-axis.

[0067] For every location on a facet of a light guide with the same radial distance ρ from the Z-axis at any arbitrary angle φ, the value of its coordinate Z(ρ,φ) is therefore the same.

[0068] Reflected or refracted perpendicularly incident light is thereby always deflected exactly to the light-collecting area with respect to φ.

[0069] One possible design involves the reflective or refractive facet of a light guide, viewed in a cross-sectional plane encompassing the Z-axis, forming a step whose Z-value increases with increasing radial distance ρ from the Z-axis. The surface of such a step can, for example, be linearly increasing with a constant slope. This angle of inclination, denoted as α The step is preferably selected such that the excitation of the desired mode with the desired node is achieved by perpendicularly incident light of the desired wavelength or wavelength range. More preferably, the step can slope down to the radially inner step height at the radially outer step end. The radially inner step height and the radially outer step height of each step can preferably be the same for all steps, in particular, they can have identical Z-positions.

[0070] One embodiment can also provide that the height and / or radial width of a facet step, as viewed in the Z-direction, increases with increasing radial distance ρ from the Z-axis. This is particularly advantageous if the light incident on the waveguide has a constant intensity profile across the waveguide surface, as is the case, for example, with sunlight.

[0071] When viewed in a projection in the Z direction, a respective light guide can preferably be circular with respect to its radially outer edge that limits the light guide, preferably wherein the at least partially ring-shaped facets and the outer edge of the light guide are arranged concentrically to the light collecting area.

[0072] In general, the waveguide can have several light guides arranged side-by-side in the XY plane or parallel to it. If the light guides had circular boundaries, such a side-by-side arrangement in a plane would result in suboptimal area coverage of the light guides and thus suboptimal efficiency of the light concentrator according to the invention.

[0073] A light guide, for example when viewed in a projection in the Z direction, can be polygonal, preferably rectangular, or more preferably square with respect to its outer edge around a respective light collecting area.

[0074] A further development, in particular of the polygonal, preferably rectangular, more preferably square edge of a light guide, but also of the other embodiments, can provide that several light guides are arranged next to each other in a plane, in particular a plane arranged parallel to the XY plane, in contact with each other, i.e. without any distance between them.

[0075] In one possible embodiment, the step height of at least one, preferably all, steps or facets of a light guide can be varied circumferentially around the Z-axis. This can preferably be achieved with a non-circular boundary of the light guide. In particular, for a light guide with a polygonal outer edge, the step height can vary depending on the distance, defined by φ, between the central axis of the respective light guide and the edge of the light guide projected in the Z-direction. This has the advantage that each angle φ can be assigned a profile Z(ρ,φ) that is optimal for light collection and achieves an optimal propagation length of the excited mode.Since, for example, the diagonal of a square is longer by the square root of two than the side length, a mode propagating in the corresponding direction for a light guide with an overall rectangular or square border requires smaller step heights to achieve a greater propagation length.

[0076] The invention may provide that the total area defined by the outer edge of a side-by-side arrangement of light guides, viewed in projection parallel to the Z-axis, forms a ratio of V:1 to the total area of ​​the respective light-collecting areas viewed in the same direction, with V greater than or equal to 100.

[0077] One possible embodiment provides that each light guide is formed from a single, preferably continuous, transparent dielectric medium, and that the light-reflecting or refracting facets of the light guide are formed by interfaces between the light guide and the adjacent waveguide material. Particularly in this embodiment, to form a totally reflective facet of the light guide, the medium of the light guide can have a refractive index lower than that of the adjacent waveguide material. For a refracting interface, the medium of the light guide can have a refractive index higher or lower than that of the adjacent waveguide material.

[0078] In particular, the adjacent material can generally be a material inserted between the light guide and a planar layer of the waveguide.

[0079] As mentioned at the outset, a light concentrator according to the invention can also be constructed from a stack of several waveguides of the type described above, arranged in the Z-direction. Here, it can be provided that in a stack of at least two, preferably symmetrical, waveguides, each comprising a light-deflectoring structure, the light-deflectoring structures of different waveguides, which at least partially overlap in the stacking direction, have light-collecting regions offset from each other perpendicular to the stacking direction. For this purpose, the waveguides as a whole can be laterally offset from each other.

[0080] Such a configuration is particularly advantageous when, in a stack of at least two preferably symmetrical waveguides, each waveguide is configured with its light-deflectoring structure to deflect a different predetermined partial spectral range from the total wavelength spectrum of light incident on the stack to the light-collecting region. Furthermore, the solar cells arranged in each waveguide or adjacent to the light concentrator can preferably be designed with efficiency optimization for the partial spectral range. This addresses the fact that a single solar cell cannot convert light into usable electrical energy with constant efficiency across the entire solar spectrum.

[0081] A waveguide can be specifically configured by adjusting the angle of inclination of the facets of the light-directing structure (determined by the step height and width) and the remaining geometric and dielectric parameters (refractive index, thickness, etc.) of the waveguide to the specific spectral range to be collected. Numerical simulation of the waveguide allows for the prediction of the partial spectral range of the guided light arriving at the light-collecting area. By varying the angle of inclination of the individual facets of the light-directing structure and the geometric and dielectric parameters of the remaining waveguide, the simulated partial spectral range arriving at the light-collecting area is adjusted to the desired spectral range. The waveguides optimized in this way can then be used as a manufacturing template.

[0082] In a possible embodiment, a light concentrator of the invention can have light guides arranged side by side in the XY plane, with dimensions of at least 10 cm in each direction perpendicular to the layering direction.

[0083] In the manufacture of a light concentrator, it may be provided that the layers of the waveguide are formed by polymer films laminated on top of each other.

[0084] A light guide can generally be formed by a cavity or several separate cavities in at least one of the layers of a layered arrangement, in particular a polymer film. Such a cavity can be realized, for example, by molding a relief and subsequently filling it with a dielectric material. At least one interface of such a cavity with the adjacent medium can form a facet of the light guide.

[0085] The invention is explained in more detail with reference to the following figures: The Figure 1 Figure 1a schematically shows a light guide 1a onto which light is incident. The upper figure illustrates that when the facets 1b of the light guide 1a have an extent Λ on the order of the wavelength λ of the incident light, diffraction effects dominate the interaction between the light and the structure. The deflection due to diffraction, caused by dispersion, depends on the wavelength. Thus, while the broadband incident beam is reflected broadband in zero order (one arrow), the beams of different colors diffracted in the 1st or -1st direction propagate in different directions (visualized by three dashed arrows each).

[0086] If, however, according to the lower figure, the extent Λ of the facets 1b of the light guide 1a is larger than the wavelength, here in the example 10 times larger than the wavelength λ of the incident light, then zero-order interactions, such as reflection, dominate. The partial interaction due to diffraction is subordinate, which is visualized by the relative length of the arrows. Dispersive effects are largely avoided. The invention takes advantage of generating predominantly zero-order light deflection, such as reflection or diffraction, by means of a light-deflectoring structure between the layer arrangements of a waveguide, thereby achieving efficient wavelength-independent deflection.

[0087] The Figure 2Figure 1 shows the schematic structure of a waveguide with a light-deflecting structure 1 embedded between two layer arrangements 2. A 100 µm thick inner region (2a, 1, 2a) of the waveguide with a grating coupler is shown.

[0088] The diagram above illustrates that with a refractive index difference of 1x 10 -1< between layers 2a and 2b of a layer arrangement 2, a large number of possible modes can be guided in the waveguide result, which is illustrated by the calculated number of transmission minima.

[0089] In contrast, the lower diagram shows that with a comparatively small refractive index difference of 4 x 10⁻⁵ in this example, only two modes can be guided in the waveguide. The calculated TE₁ mode exhibits an intensity profile in the Z direction whose local minimum, Iₘₘ, coincides spatially with the light-deflectoring structure 1. The significantly longer propagation length of this mode compared to TE₁ is evident from the much narrower resonance.

[0090] The calculation thus demonstrates that even with large layer thicknesses, which are significantly larger than the wavelength of the incident and guided light, singular modes can be guided in the waveguide, whose intensity minimum with respect to z lies on the light-deflectoring structure 1.

[0091] The solution for achieving a reduced interaction between the guided mode and the light-deflectoring structure 1 therefore consists in reducing the refractive index difference Δ n between the materials at the interface causing total internal reflection. In this simulation, a stepwise variation of the refractive index at a fixed interface is assumed. In reality, a change in the refractive index caused, for example, by doping, can also be generated continuously over a certain extent Δz in the direction of z, so that total internal reflection no longer occurs at a fixed, localizable interface at constant z, but is distributed over the region Δ z , in which the index gradually increases from the inside out by Δ n is reduced. In this case, the step waveguide does indeed transition into a gradient waveguide, but the essential statement remains: with decreasing Δ nWith the same thickness of the inner region of the waveguide, the number of modes in the waveguide also decreases.

[0092] The Figure 3 shows one within the inner area with nor > on guided mode, which has a specific intensity distribution for it I ( z The structure 1 and the layers of the layer arrangements 2 adjacent to the structure 1, arranged on both sides around the light-deflectoring structure, together form the inner region 2a of the waveguide.

[0093] Shown is I ( z ) a largely undisturbed view due to the light-deflecting structure (e.g., due to n r ≈ nor ) TE 1 Mode, which is located in the outer area with on the field distribution decreases exponentially and in the inner region is approximately sinusoidal E(z) with a zero at z exhibits zero. This zero point is also present in the intensity distribution. I ( z )~E ( z ) is present and is called a node. For all x, y (Cartesian) and accordingly for all ρ, φ (Cylinder coordinates) disappears at z = z 0 is the mode. The corresponding plane is therefore called the nodal plane. Structure 1 now lies with a thickness or extent ts in the direction of z within the fashion-leading layer with nor the thickness you , whereby accordingly ts < you This must apply. The extent of the light-deflecting structure 1 extends along the z-axis across the entire area. with s- < z ≤ z s + . The fill factor F indicates the proportion of the mode that is guided within the light-deflecting structure 1: F = ∫ z s − z s + I z / ∫ − ∞ ∞ I z .The aim is to minimize this fill factor of the mode within the light-deflecting structure 1 as much as possible. For this purpose, it is particularly desirable that the node plane lies within the light-deflecting structure 1 ( with s- < with 0 ≤ with s+ ) or at least in their vicinity ( z 0 - with s+ < you or with s- - z 0 < you ) .

[0094] In a preferred embodiment, the fill factor F of the mode is less than 10 -3< , particularly preferably less than 10 -5< .

[0095] The Figure 4 visualizes a preferred embodiment of the invention, in which a for | z | ≥ zc a symmetrical layer structure of the waveguide of a light concentrator according to the invention is present.

[0096] So that the node position of a TE 1 mode or a TM 1 mode is always at z, regardless of the wavelength. 0 If the nodes are located in a given position, symmetry with respect to the z-axis is necessary. The same applies, incidentally, to the middle i+1th nodes of higher odd-numbered TE 2. i +1 or TM 2 i +1 modes, which are therefore also broadband usable. The symmetry is lost outside a region of extent 2. zc required, which the light-deflectoring structure 1 and the material areas directly adjacent to structure 1 with refractive index n 1,- and n 1,+ completely surrounds. The layer arrangements 2 are on both sides of the area with the extent 2. zc arranged and partially intersect within it. To simplify notation, it is useful to choose the zero coordinate z = 0 so that it lies exactly in the middle of this area. Within the area excluded from the symmetry requirement (- zc < z < zc ) the structure must be 1, so in particular zc ≥ with s+ and with s- ≥ -zc Since this area is asymmetrical, the node position can z 0 deviates slightly from z = 0. Outside this range, i.e., for all | z | ≥ zc Symmetry should prevail. However, due to manufacturing-related inaccuracies, a slight deviation from this requirement is permissible, which should be reflected in the tolerance factor K. Ideally, K = 1. In a layered structure, symmetry with respect to the indices and thicknesses should prevail both in the inner and outer areas: n i,j - = Kn i,j+ and t i,j - = Kt i,j+ for all j from 1 to M and n a,k - = Kn a,k+ and t a,k - = Kt a,k+ for all k from 1 to N.Total internal reflection occurs at the interface (dashed line) between the Mth inner layer and the first outer layer. Therefore, the following applies in particular: ni,M+ > n a, 1+ and ni,M- > n a, 1 - . In the outer area, the trend diminishes with increasing distance from this boundary. If a l .th outer layer a

[0097] Distance ∑ k = 1 l − 1 t a , k + ≈ ∑ k = 1 l − 1 t a , k − > t i 2 If this interface has a symmetry, then this layer has hardly any influence on the fashion. Accordingly, outer layers may deviate from the symmetry requirement and may even have a higher refractive index than ni,M+ ≈ ni,M- exhibit. Without this end of a waveguide for high | z Stacking different waveguides would not be possible. If the number of layers ( N, MIf the index difference between adjacent layers and the thicknesses of the individual layers become very large, then the layer-by-layer structure can also be used to describe a gradient waveguide. However, in this case, a functional n ( z ) more obvious. If the transition between the inner and outer regions becomes continuous, total internal reflection occurs within a volume and no longer at an interface. This is indicated by the broadened dashed line in the lower image. This entire volume is assigned to the outer region. For the far outer regions of the waveguide, which are more than 1000 meters from the outermost edge of this volume, the following applies: t i 2 Since they are far apart, symmetry requirements no longer apply. Apart from this limitation, the n ( z ) for everyone | z | ≥ zc be symmetrical ( n ( z ) = Kn ( -z )). Preferably Kin the range of 0.99 < K < 1.01, further preference should be given to K in the range of 0.999 <K<1,001, weiter bevorzugt soll K im Bereich 0,9999<K<1,0001, weiter bevorzugt soll K im Bereich 0,99999<K<1,00001

[0098] Figure 5 The effect of the light concentrator according to the invention is explained using the principle of reciprocity. The light coupled out from a homogeneous one-dimensional grating coupler as a light guide 1a has an exponential intensity distribution. I ( x ) . For optimal light collection, i.e., for the reciprocal process, the light to be collected must also exhibit such a distribution. To be able to collect light over long distances, the coefficient of light (a) must become small, which is achieved through the concept of nodes.

[0099] The invention can be applied according to Figure 6 provide that with increasing radial distance ρfrom the Z-axis the height and / or radial width of the step of a light guide 1a formed by a facet 1b increases in the Z-direction.

[0100] In a radially symmetrical arrangement, the coupling of a cylindrical wave running from the inside out would result in a dependency I ( ρ ) exhibiting, which, in addition to the described exponential term, also have a reciprocal of ρ exhibits a dependent factor, since the intensity itself, even without coupling out, increases with increasing cylindrical surface area due to the growing area illuminated by the light. ρ would decrease. To prevent this sharp decline I ( ρ To compensate, it is necessary to increase the height of the steps as the ρ to allow it to rise. The greatest extent (at maximum ρ, i.e., outside in the light guide) then defines the ts or the values z s- and z s+ .

[0101] Such a design of the light guide is therefore preferred for collecting and concentrating sunlight that falls on a waveguide of the invention with a uniform intensity distribution.

[0102] The Figure 7 Figure 1 shows the design of a light guide 1a formed as a reflector from reflective facets 1b, which surround the light collecting area 3 in the center of the light guide 1a of the structure 1 in a ring shape.

[0103] The facets 1b can be completely rotationally symmetric, as shown here, while the edge of the light guide can be shaped independently of the facets located in the interior of the light guide. In this example, the outer edge 4 of the light guide 1a of structure 1 is circular. A change from Cartesian to cylindrical coordinates is useful. With complete rotational symmetry, the z ( ρ) is the same for all φ. More generally (even with piecewise rotational symmetry), the normal vector shows (here using the example) n 4 ), apart from the facet edges, exactly on the z-axis, which is particularly noticeable when projected into the XY plane (bold arrow in each case).

[0104] The Figure 8Figure 1 shows an embodiment in which the facets 1b of the light guide in the interior of the light guide 1a are rotationally symmetric. The outer region of the light guide 1a, or rather the edge 4 and the light guide 1a as a whole, is square. Here, too, the embodiment is such that, with the exception of edge 4, the normal vectors on every possible facet 1b of the light guide 1a of structure 1 point exactly to the Z-axis for the facets inclined reflectively towards the light-collecting area 3, and away from the Z-axis for the faces facing away from the light-collecting area; in other words, the vectors have no φ component in the cylindrical coordinate system. The facets are each designed to surround the light-collecting area 3 in a ring-like or at least partially ring-like manner and have a step shape, with a step width increasing with increasing radial distance from the light-collecting area along ρ and a step height increasing along the Z-axis.

[0105] The Figure 9It also shows a square-bordered version of a light guide, as in the Figure 8 This can be advantageous for better utilizing a surface with light guides. However, this means that a greater propagation length must be achieved along the direction specified by φ₂ than in the direction specified by φ₁. Accordingly, in the direction specified by φ₂, shallower steps of the light guide 1a formed by the facets 1b are required for the same ρ, which means φ components that deviate from zero. Therefore, the design here is such that the step height varies depending on the angle φ around the Z-axis, decreasing in particular towards the corner of the square edge of the light guide 1a in the projection when ρ is constant.

[0106] Figure 10 shows a concretization of the non-zero φ components of the normal vectors on the facets 1b of the light guide 1a according to Figure 9This means that the normal vectors on the reflecting facets 1b of the light guide 1a no longer point exactly to the Z-axis at every arbitrary position of a reflecting surface. Preferably, the deviation from symmetry is chosen such that the normal vectors of each facet 1b of the light guide 1a of the light-deflecting structure 1, projected into the Z-plane, are, for every considered distance ρ on the reflective surfaces at least within a value range defined by half the diameter of the light-collecting area 3 ρ ≤ ρ 0 / 2, which points to the Z-axis with a radial distance ρ surrounds 0 and thus a tolerance range of the φ-components of the said normal vectors of |φ| ≤ arcsin ( ρ 0 / 2 ρ ) defined.

[0107] The Figure 11shows several possible design variants in which the facets 1b of a light guide 1a do not cause a single reflection, as in the previous designs, but rather a light-refracting transmission or multiple reflections.

[0108] In the two transmitting embodiments shown, the facets 1b of the light guide 1a are replaced by bodies 1c with refractive index n r formed and exhibit two refracting facets 1b illuminated in transmission. The bodies 1c in the shown transmitting configurations can be described as regions of high-refractive-index material with n r > nor or nor > n r or be formed as a material recess, in particular a gas-filled or evacuated material recess, in the layers of the waveguide.

[0109] In the multi-reflective configuration shown, total reflection, in particular double total reflection followed by transmission out of the bodies 1c, can also occur within the bodies 1c. The bodies 1c can be considered regions of high-refractive-index material with n r > nor be formed in the layers of the waveguide.

[0110] The Figure 12 The two upper sub-images show two different designs for extracting the collected light by means of an extraction element 5 offset in the negative Z direction from the light-collecting area 3 of the light guide 1a.

[0111] In the first variant, the coupling element 5 is formed by a material recess in the light-guiding medium with refractive index nor in the form of a rotationally symmetrical cone with an opening angle β realized, so that the medium located in the cone ( nk) corresponds almost or exactly, or at least essentially, to a refractive index of one. When the light now strikes the interface of the cone, i.e., the output coupling element 5, the light guided in the waveguide is refracted according to the law of reflection with an effective index of the mode and the opening angle. β The emission angle, determined by numerical simulation, is deflected out of the concentrator as indicated by the black arrows.

[0112] In the second (light guide according to Figure 9 In variant ) the coupling element 5 consists of a version of facet 1b inverted in the ρ and Z directions at the intensity maximum of the mode guided in the waveguide, as considered in the Z direction. This results in efficient coupling in the direction of incidence, as indicated by the black arrows.

[0113] The third and fourth partial images show one according to the Figure 9and the first left partial image combined waveguide with a contacting arrangement of side-by-side light guides and cone-shaped coupling elements 5.

[0114] The Figure 13 Figure 1 shows the molding process for structuring the inner region of waveguide 2a using thermal pressing. The inner region of waveguide 2a, located on a substrate 6, has a refractive index of [missing value]. nor The material is brought into contact under pressure and temperature with a mechanically hard negative die 7 with a negative relief (8) to be embossed located on it between two press shoes (9), so that the material of the inner area of ​​the waveguide assumes the shape of the under plastic deformation and thus has a now positive relief 10.

[0115] Figure 14 shows the production of a waveguide by filling a positive relief 10 created by the molding process according to Figure 13and the subsequent creation of the layer arrangement by lamination of layers.

[0116] After the impression was taken according to Figure 13 As shown in the first image, there is a layer nor The system consists of a lower smooth interface viewed in the Z-direction and an upper structured interface. The structured interface can then be, for example, coated with a closed layer of refractive index by rotational coating. n r to be filled, which forms the structure 1 together with the light guides 1a, with the facets being formed by the interfaces between the areas with refractive index nor and n r are formed (second image). After this arrangement is detached from substrate 6, the layer with refractive index is exposed as shown in the third image. nor another layer with refractive index onlaminated on. On the previously exposed interfaces of the structure, however, a layered arrangement of two layers with the respective refractive indices is applied. nor and on laminated, so that a symmetrical waveguide is now present with respect to a middle plane lying in the structure (fourth partial image).

[0117] The Figure 15 shows a design for setting up wavelength-selective concentrators.

[0118] In the cross-section of the rotationally symmetric waveguide, each facet 1b of a light guide 1a forms a step with a slope angle. α .

[0119] Numerical simulations show that the light concentrated in the waveguide has a spectral range of width Δ λ exhibits which of this incline angle αand depends on the other geometric and dielectric parameters (refractive index, layer thickness, etc.) of the waveguide. To adapt a waveguide to a predetermined spectral range, it is parameterized for numerical calculation and optimization. The spectrum of guided light arriving at the light-collecting region serves as a reference for the desired spectrum. By optimizing the parameters, this guided light arriving at the light-collecting region is adjusted to the desired spectrum. The determined waveguide parameters then serve as manufacturing parameters for the waveguide.

[0120] The Figure 16 shows a sunlight-optimized design of a fully integrated light concentrator consisting of a combination of three stacked wavelength-selective waveguides with a respective side-by-side arrangement of light guides according to the Figuren 12 and 15Each of the three waveguides collects and concentrates a complementary part of the entire incident solar spectrum. For clarity, only the parts of the light-guiding layer containing the respective light-deflectoring structures and coupling elements are shown, while the subsequent layers 2b of the waveguides are indicated by the black dots. Each waveguide is numbered with the index following the layer designation, so, for example, the thickness of structure 1 of the upper waveguide is designated as . t s,1. Below the fully integrated light concentrator is a matrix arrangement of solar cells 11, illustrated by black cuboids, consisting of n rows of solar cells. A relative lateral displacement of the waveguides relative to each other allows for a cyclic arrangement in the displacement direction of a total of n complementary solar cell rows 11-1, 11-2 and 11-3, ..., 11-i, 11-i+1, ..., 11-n, each with a band gap energy adapted to the wavelength-selective waveguide centered above it, and thus an optimized conversion of collected light energy into electrically usable energy. Examples are shown in Figure 17This image shows a total of 12 solar cell rows, with the points in the upper part of the image symbolizing the continuation in the dislocation direction of such a cyclic configuration. The solar cells can be applied directly by transfer printing or pick and place. The corresponding decoupling elements serve as positioning markers in each case.

[0121] The Figure 17 The figure schematically illustrates the relationship between the light-deflecting structure 1 and the light guides 1a, which are represented by squares in a plane parallel to the XY plane. In this example, the light-deflecting structure 1 is composed of sixteen light guides. In general, any arrangement of arbitrary light guides 1a forms the light-deflecting structure 1.

Claims

1. Light concentrator comprising at least one waveguide, wherein the at least one waveguide comprises a light-deflecting structure (1) which is located between two layer arrangements (2) of in each case at least two transparent dielectric layers layered in a layering direction and by means of which light from at least one predetermined wavelength range incident on the at least one waveguide can be steered into the waveguide, wherein at least one mode from the at least one predetermined wavelength range can be guided in the waveguide by total-internal reflection, the intensity distribution of said mode having, as viewed in the layering direction, at least one local intensity minimum (Imin) which is arranged within the light-deflecting structure (1), characterized in that the light-deflecting structure (1) comprises a light guide (1a) or multiple light guides (1a) arranged next to one another perpendicular to the layering direction, wherein a respective light guide (1a) comprises facets (1b) which are each embodied to be longer than the longest wavelength from the predetermined wavelength range in each of three mutually perpendicular spatial directions and by means of which the incident light can be deflected in the direction of a light collection region (3) assigned to the light guide (1a), wherein a facet is formed by an interface between two dielectric media with different refractive indices, wherein at both transitions between the inner region (2a) and the outer region (2b) of the layer arrangements (2) at which the total-internal reflections are made possible by virtue of there being, at the transition, in each case a stepwise or spatially distributed transition from the higher refractive index in the inner region (2a) to a refractive index in the outer region (2b) which has been reduced by a refractive index difference, and wherein this refractive index difference is less than 1x10-3.

2. Light concentrator according to Claim 1, characterized in that, in the layering direction below or above the light collection region (3) or an output coupling element (5), an arrangement to be illuminated is arranged within a layer or on the surface of a layer of the waveguide and illuminated by light emerging from the light collection region (3) or output coupling element (5).

3. Light concentrator according to either of the preceding claims, characterized in that the light collection region (3) is formed by a region of the light guide (1a) in the centre thereof.

4. Light concentrator according to any of the preceding claims, characterized in that an output coupling element (5) for output coupling light a. is located above or below the light collection region (3) and / or light guide (1a) when viewed in the Z-direction, in which the layers of the layer arrangements are layered, or b. is designed as a material cutout of the structure (1) and / or at least one of the waveguide layers, or c. is designed as a scattering or diffracting or reflecting arrangement, preferably as a total-internal reflection arrangement, which with respect to the layering direction is offset from the light-deflecting structure (1) with which light can be deflected from the direction of a mode propagating in the waveguide.

5. Light concentrator according to any of the preceding claims, characterized in that each of a plurality of waveguides is symmetric in such a way with respect to the layering direction z that three regions excluded from the symmetry are defined: a. firstly, a region of the waveguide with the extent 2zc, in which the light-deflecting structure (1) is situated and in the centre plane of which z=0 is located, b. secondly, the regions which start at greater than or equal to half the value of the dimension (ti) of the extent of the inner region (2a) outside the inner region (2a) of the waveguide, as viewed in the layering direction, but that, apart from the above-mentioned restriction, the refractive index n(z) is symmetric for all |z| ≥ zc, where n(z) = Kn(-z), where K is in the range 0.99 < K < 1.01.

6. Light concentrator according to any of the preceding claims, characterized in that at least some of the facets (1b) of a light guide (1a) of a light-deflecting structure (1) surround a respective light collection region (3) in an at least partially frame-shaped manner, and each light guide (1a) comprises at least one reflective or total-internal reflection facet (1b) or comprises at least two facets (1b) at which transmitted light is refracted in each case such that the light incident on the surface of a respective light guide (1a) can be deflected in the direction of the respective light collection region (3) as a result of this reflection or total-internal reflection or refraction.

7. Light concentrator according to any of the preceding claims, characterized in that given an assumed origin of a cylindrical coordinate system at the centre of the light collection region (3), a respective light guide (1a) comprises one or more reflective or light-refracting facets (1b) which surround the Z-axis at least in regions, wherein the normal vector has a φ component of zero for each location on the facet (1b).

8. Light concentrator according to any of the preceding claims, characterized in that the at least one reflective or light-refracting facet (1b) of each light guide (1a), as viewed in a sectional plane comprising the Z-axis, forms a step which increases in Z-value with increasing radial distance ρ from the Z-axis.

9. Light concentrator according to any of the preceding claims, characterized in that for any location on the facet (1b) of the light guide (1a) with the same radial distance ρ from the Z-axis at any angle φ, the value of the coordinate Z(ρ,φ) thereof is the same.

10. Light concentrator according to any of the preceding claims, characterized in that the height, as viewed in the Z-direction, and / or radial width of the steps of a respective light guide (1a) increase with increasing radial distance ρ from the Z-axis.

11. Light concentrator according to any of the preceding claims, characterized in that when viewed in a projection in the Z-direction, a respective light guide (1a) is of circular form with respect to its radially outer delimiting edge (4).

12. Light concentrator according to any of preceding Claims 1 to 10, characterized in that when viewed in a projection in the Z-direction, a light guide (1a) is of polygonal form with respect to its outer delimiting edge (4).

13. Light concentrator according to any of the preceding claims, characterized in that within a light-deflecting structure (1), a plurality of light guides (1a) are located in a plane and their edges (4) are arranged so as to make contact with one another.

14. Light concentrator according to any of the preceding claims, characterized in that the step height of at least one facet (1b) of a light guide (1a) varies in the circumferential direction about the Z-axis.

15. Light concentrator according to any of the preceding claims, characterized in that each light guide (1a) is formed from a transparent dielectric medium, and a reflective or light-refracting surface of the light guide (1a) is formed by a continuous structured interface between the light guide (1a) and the material of the waveguide adjacent thereto.

16. Light concentrator according to any of the preceding claims, characterized in that the refractive index difference between the inner region (2a) and the outer region (2b) of a respective layer arrangement (2) is obtained by different doping of the same host material.

17. Light concentrator according to any of the preceding claims, characterized in that in a stack of at least two symmetric waveguides which each comprise a light-deflecting structure (1), the light-deflecting structures (1) of different waveguides which overlap one another in the stacking direction have light collection regions (3) offset with respect to one another perpendicular to the stacking direction and correspondingly offset output coupling elements (5).

18. Light concentrator according to any of the preceding claims, characterized in that the layers of the waveguide are formed by polymer films laminated onto one another.

19. Light concentrator according to any of the preceding claims, characterized in that a respective light guide (1a) is formed by a transition of a relief (10) of facets (1b) on the surface of a dielectric medium to another other dielectric medium completely covering this relief (10) or a cavity in at least one of the layers of a layer arrangement (2).