APERIODIC NANO-OPTIC ARRAY FOR ANGLE SHAPED INCOHERENT EMISSIONS

Abstract

A lighting element (200), comprising a light source (210) for emitting a first beam of light having a wavelength within a first wavelength range; a converting material arranged in a phosphor layer (220) such that the light beam is incident on the converting material, wherein the converting material emits a second light beam with wavelengths within a second wavelength range, the second wavelength range being different from the first wavelength range and having wavelengths from 500 nm to 650 nm; and a dielectric aperiodic array (120) arranged on the phosphor layer (220), wherein the dielectric aperiodic array (120) comprises a plurality of dielectric scattering columns (100) that are smaller than the wavelength of the light and are arranged to form an aperiodic pattern, and wherein the dielectric aperiodic array (120) is configured to produce an azimuthal isotropic scattering of the incident luminescence within a limited angular cone (1207) such that more than 85% of the total generated light emission is emitted into an angular cone of ± 60°, wherein the angular cone of ± 60° corresponds to an angular cone into which the phosphor layer (220) emits 75% of the total generated light emission, and wherein the phosphor layer (220) is unstructured and optically thick.

Description

Cross-reference to the relevant registration

[0001] The present application is an international application and claims priority over US patent application No. 16 / 181,284, filed on November 5, 2018, entitled “Aperiodic Nano-Optical Array for Angular Shaping of Incoherent Emissions”, which is fully incorporated herein by reference. TECHNICAL FIELD

[0002] Embodiments in this application generally relate to structures formed on surfaces to shape the light emitted by a luminescence source. BACKGROUND

[0003] Document US 2012 / 0086036A1 describes a light-emitting component. Document US 2014 / 0016181A1 describes optical components with spiral aperiodic structures for circularly symmetrical light scattering. The publication DE 11 2006 000 484 T5 describes an electromagnetic device with an integral non-linear component.

[0004] Publication US 2017 / 0 082 263 A1 describes collimating metal lenses.

[0005] The publication LAWRENCE, Nate; TREVINO, Jacob; NEGRO, Luca Dal: Control of optical orbital angular momentum by Vogel spiral arrays of metallic nanoparticles. In: Optics letters, Vol. 37, 2012, No. 24, pp. 5076-5078. ISSN 0146-9592 describes the control of optical angular momentum by Vogel spirals made of metallic nanoparticles.

[0006] The publication NISHIYAMA, Norimasa [et al.]: Transparent polycrystalline cubic silicon nitride. In: Scientific reports, Vol. 7, 2017, (44755) pp. 1-8. ISSN 2045-2322 describes transparent, polycrystalline cubic silicon nitride.

[0007] Document US 2013 / 0 235 557 A1 describes a light source.

[0008] Document US 2013 / 0 242 543 A1 describes a white light LED component.

[0009] The publication by GUO, Ke [et al.]: “Broadband light scattering and photoluminescence enhancement from plasmonic Vogel's golden spirals”, Laser Photonics Rev. 11, No. 3, 1600235 (2017) describes plasmonic nanoarrays for scattering broadband light. Many modern systems implement photonics in some form. For example, many modern electronic devices generate light in some way. A significant problem with a number of light emission systems (e.g., projectors, car headlights, structured lighting systems, etc.) is that the emission from the light-emitting device occurs in a hemispherical distribution. This makes efficient light collection from such light-emitting devices difficult at large collection angles. Typically, collimation optics for such systems include multiple aspherical lenses and large convex mirror structures. Therefore, it is difficult to fabricate compact light sources.For example, manufacturing cost-effective and / or space-saving collimation optics for angles beyond ±60° is extremely difficult, especially when the numerical aperture exceeds 0.87. Furthermore, maintaining high image quality or high contrast in every projected image is challenging. In some cases, foregoing light collection beyond angles of ±60° results in a loss of approximately 25% of the total emitted light.

[0010] Some lighting applications utilize phosphor-based converting materials to convert high-power pump light into longer-wavelength light. For example, blue or ultraviolet (UV) light-emitting diodes (LEDs) can be used to generate white or other desired longer-wavelength emissions from phosphor materials. However, such light-conversion devices suffer from similar problems to other light-emitting devices, as collecting emissions at wide angles is challenging. Several methods for collecting light emissions from phosphor-converted light sources at wide angles have already been proposed.

[0011] For example, gluing a lens to the surface of the fluorescent panel can improve the light emission from the phosphor into the air, but at a high cost in luminance. The luminance can be reduced by at least a factor of (n). lens / nph ) 2 decrease, where n lens the refractive index of the lens material and n ph The refractive index of the phosphor is crucial. As a concrete example, consider the case of yttrium aluminum garnet (YAG) compared to silicone, which corresponds to a luminance loss of approximately (1.41 / 1.83)^2 = 0.59. For longer-wavelength phosphors (e.g., with red-emitting nitrides), the refractive indices are on the order of 2.0 to 2.2, resulting in an even greater luminance loss.

[0012] Collecting wide-angle emissions using external optics with very large collection angles is another example of how the luminance reduction problem described above can be mitigated. However, depending on the optics used, various disadvantages arise with regard to chromatic aberration, color separation, limited collection angles, cost, size, and weight. Furthermore, the etendue of a light source comprising a converted LED (e.g., a phosphor-converted LED or similar) and external optics is limited by the etendue of the converted LED. Thus, the etendue is not reduced by the external optics.

[0013] In another example, a photonic grating consisting of columns arranged in periodic arrays can be applied to the surface of the phosphor. The photonic grating functions similarly to a two-dimensional (2D) grating, diffracting the internal light distribution within the phosphor into desired emission directions. Such grating structures can narrow the emission angles in some cases, but several problems arise. First, the high symmetry of these structures, along with the small number of discrete diffraction orders, creates light concentrations in the far-field emission. Second, because spatially periodic structures generate corresponding periodic scattering k-space vectors, the possible scattering patterns for a given incident luminescent k-vector are limited.This effect limits the selection of possible far-field patterns, including those that provide a narrow angular distribution of emission in the far field. Since the selection of diffraction patterns is limited, it is very difficult to achieve both directed emission and high extraction efficiency. Thirdly, because the k-space vectors for periodic structures are sparsely filled, the highest extraction efficiency of modified directionality emission cannot be achieved.

[0014] In light of the aforementioned problems and difficulties, the present disclosure is provided.

[0015] The lighting element includes: a light source for emitting a first beam of light which has a wavelength within a first wavelength range; a converting material arranged in a phosphor layer such that the light beam falls on the converting material, wherein the converting material emits a second beam of light with wavelengths within a second wavelength range, the second wavelength range being different from the first wavelength range and having wavelengths from 500 nm to 650 nm; and a dielectric aperiodic array arranged on the phosphor layer, wherein the dielectric aperiodic array comprises a plurality of dielectric scattering columns smaller than the wavelength of the light and arranged to form an aperiodic pattern, and wherein the dielectric aperiodic array is configured to produce an azimuthal isotropic scattering of the incident luminescence within a limited angular cone such that more than 85% of the total generated light emission is emitted into an angular cone of ± 60°, wherein the angular cone of ± 60° corresponds to an angular cone into which the phosphor layer emits 75% of the total generated light emission, and the phosphor layer is unstructured and optically thick.

[0016] The arrangement includes: a substrate that is a phosphor layer, wherein the phosphor layer is unstructured and optically thick and is configured to generate light in a wavelength range of 500 nm to 650 nm, and A plurality of dielectric scattering columns, smaller than the wavelength of the light, arranged on the substrate to form a dielectric aperiodic array with an aperiodic pattern, the plurality of dielectric scattering columns of the aperiodic pattern working together to produce an azimuthal isotropic scattering of the incident luminescence within a limited angular cone, such that more than 85% of the total generated light emission is emitted into an angular cone of ± 60°, the angular cone of ± 60° corresponding to an angular cone into which the phosphor layer emits 75% of the total generated light emission.

[0017] The procedure for producing an arrangement includes: Applying a pattern for marking a plurality of dielectric scattering columns, smaller than the wavelength of light and arranged in a dielectric aperiodic array, onto a substrate comprising a converting material arranged in a phosphor layer and arranged to emit light with first wavelengths of 500 nm to 650 nm in response to the incident light of a second, different wavelength, and Formation of the multitude of dielectric scattering columns, which are smaller than the wavelength of the light, on the substrate, where the phosphor layer is unstructured and optically thick, wherein the pattern of the plurality of dielectric scattering columns, which are smaller than the wavelength of the light, is arranged such that it produces an azimuthal isotropic scattering of the incident luminescence within a limited angular cone, such that more than 85% of the total generated light emission is emitted into an angular cone of ± 60°, wherein the angular cone of ± 60° corresponds to an angular cone into which the phosphor layer emits 75% of the total generated light emission. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1A shows an example of a dielectric column according to different embodiments. Fig. Figure 1B shows an example of an aperiodic array consisting of a number of dielectric columns according to different embodiments. Fig. Figure 2 shows a first example of a lighting element according to various embodiments. Fig. 3A, Fig. 3B and Fig. 3C shows examples of aperiodic arrays based on the Vogel's spiral according to various embodiments. Fig. Figure 4 illustrates a first diagram according to different embodiments. Fig. Figure 5 illustrates a second diagram according to different embodiments. Fig. 6A, Fig. 6B, Fig. 6C and Fig. Figure 6D shows example graphics according to different embodiments. Fig. Figure 7 shows another example diagram according to different embodiments. Fig. Figure 8 illustrates a logical sequence according to different embodiments. Fig. 9A, Fig. 9B, Fig. 9C, Fig. 9D, Fig. 9E, Fig. 9F, Fig. 9G and Fig. Figure 9H illustrates an exemplary aperiodic array during different manufacturing stages according to different embodiments. Fig. 10A, Fig. 10B and Fig. Figure 10C shows diagrams of various experimental variations of the parameters of an aperiodic array according to different embodiments. Fig. Figure 11 shows a second example of a lighting element according to different embodiments. Fig. Figure 12 shows a third example of a lighting element according to different embodiments. Fig. Figure 13 shows a fourth example of a lighting element according to different embodiments. DETAILED DESCRIPTION

[0018] Various embodiments relate to aperiodic arrays that are deposited or formed on the emission side of a surface of an emitting or wavelength-converting material. Generally, the aperiodic array is formed from a number of nanostructures arranged in a two-dimensional (2D) aperiodic pattern. As mentioned earlier, converting materials are frequently used to convert pump light into longer-wavelength light in order to access spectral ranges that are not available through the direct conversion of electricity to light (or to provide light there with better efficiency). The present disclosure can be applied to light-emitting devices that use phosphors. For example, phosphor conversion of blue or UV LEDs is often used to generate white or other desired longer-wavelength emissions.An aperiodic array of structures can be applied to the surface of the phosphor to focus the emission into a desired distribution shape or within an angular limit.

[0019] In some embodiments, the present disclosure provides a number of dielectric scattering columns arranged to form a densely packed aperiodic array, such as a Vogel's spiral, wherein the geometries of the aperiodic spiral produce an azimuthal isotropic scattering of the luminescence within a limited extraction angle cone. The extraction angle cone is uniquely defined by the aperiodic geometry of the spiral. Thus, parameters of the spiral such as the scaling factor, divergence angle (i.e., golden angle), aspect ratio of the columns, or similar parameters can be manipulated to provide a desired extraction angle cone.

[0020] In contrast to periodic structures, aperiodic structures can generate far-field patterns (Fourier transforms) that do not exhibit preferred azimuthal directions. Therefore, the aperiodic structures of this disclosure can provide a limitation of light emissions to a desired angular emission cone. It is noteworthy that the highest density of extracted k-vectors near the forward direction can only be achieved when considering the diffraction of structures that possess ring-shaped regions in their Fourier spectrum. This can be derived from kinematic diffraction theory. However, this condition cannot be satisfied with conventional periodic arrays.

[0021] Accordingly, the present disclosure provides aperiodic structures with rotationally symmetric k-space, designed to satisfy the kinematic scattering condition for directed forward extraction. For example, this type of structuring can reduce light emission in far-field emission angles above ±60°. As mentioned previously, emission from the light-emitting device occurs in a hemispherical distribution, often well approximated by a Lambertian law (especially for the optically thick, luminescent, radiation-converting (or generating) layer). Structures and devices according to the present disclosure can thus significantly improve the collection efficiency of secondary optics or downstream projection systems compared to the efficiency of conventional systems.It is commendable that the collection efficiency is increased without unwanted artifacts at large angles, which are typical for traditional periodic structures.

[0022] Light-emitting components implementing this disclosure can be smaller than conventional devices due to the reduced requirements for the collecting angle. Furthermore, a smaller collecting angle can reduce aberrations, resulting in higher image quality or projection of the light source. This can be advantageous in a number of applications, such as forward lighting of motor vehicles, where a high-contrast projection onto the road is required to minimize glare.

[0023] In various embodiments, the present disclosure provides that some light emissions (e.g., above the far-field emission angles) are scattered back into the conversion material (e.g., phosphor or similar). By backscattering light that would otherwise be emitted outside the desired emission angle into the conversion material, the angle limitation has a minimal impact on efficiency. Thus, for example, the losses in a phosphor-converted LED can be kept low, with total losses being lower than with simply clipping the emission to a desired cone. This can offer higher extraction efficiency compared to conventional emission extraction methods. Another advantage is that the source's étendue (emitting surface area) is reduced without significantly degrading the overall efficiency, while increasing the luminance.A concrete example: when light is emitted from a fluorescent panel with volume scattering, the internal radiation striking the emitting surface approximately follows Lambert's law. If the emitting surface also lacks any structures for angle control, the light emission is likewise Lambertian (because the radiance remains constant), meaning that the light emitted into a ±60° angle cone can account for approximately 75% of the total generated light emission. In some embodiments described here, the light emission into the same specific angle cone can exceed, for example, 85–90%, depending on the effective reflectance of the pump light source.

[0024] In some embodiments, the aperiodic structure can be applied to the phosphor converter in a chip-level conversion (CLC) configuration. For example, the phosphor converter can be a flat plate bonded to a pump LED emission surface (e.g., by adhesive or other bonding materials). The phosphor then emits directly into the air from a flat surface whose area is equal to (or similar to) the emission surface of the pump device. In such embodiments, the aperiodic structure can reduce the emission angle while maintaining the minimum emission area of ​​the phosphor surface, particularly when emission from the edges of the phosphor plate is masked by highly reflective media, such as highly enriched TiO2 powder in a silicon matrix.Accordingly, the luminance (or radiance) can increase - with a minimal disadvantage for the total luminous flux or radiant power.

[0025] Fig. Figure 1A illustrates an exemplary embodiment of a dielectric scattering column, while Fig. Figure 1B illustrates an exemplary embodiment of an array consisting of a number of dielectric scattering columns made of Fig. 1A is formed. Fig. Figure 1A shows a dielectric scattering column 100, also referred to here as a "nanostructure" or simply as a "structure". The structure 100 is shown as a cylinder with a height (h) 101 and a diameter (D) 103. The structure 100 can be made of the same material as the one in Figure 1A. Fig. The phosphor emitter layer 220 shown in Figure 2 is formed. In some embodiments, the structure 100 can be formed from a dense titanium dioxide (TiO2) foil / thin film. Furthermore, in some embodiments, the structure 100 need not be cylindrical in shape. For example, the structure can be rectangular, conical, or pyramidal, and have dimensions that depend on the refractive index of its material.

[0026] An aperiodic array can be formed from a number of structures 100. In Fig. Figure 1B, for example, represents an aperiodic array 120 containing a number 100 structures. More precisely, an aperiodic pattern can be formed from a number of columns 100-1, 100-2, 100-3, 100-4, ... 100-n (where n is a positive integer). The columns 100 within the aperiodic array 120 are spaced at an average center-to-center distance. <r>105 are spaced apart. As used herein, the term "center-to-center" or "center-to-center distance" means the average distance from the center of one column 100 to the center of an adjacent column 100. The center-to-center distance is often referred to as <r>This is referred to as... For example, <r>105 in Fig. Figure 1B shows the line from the center of one column 100 to the center of an adjacent column 100. In particular, it represents <r>105 in Fig. 1B the average center-to-center distance <r>105 from the center of column 100-3 to the center of column 100-4. More precisely, if here on <r>The reference made is to the average of the center-to-center distances of all columns. It should be noted that the distance between selected columns 100 (e.g., between columns 100-1 and 100-2) is not necessarily the same as the distance between other selected columns (e.g., between 100-2 and an adjacent column next to 100-1).

[0027] The aperiodic array 100 can be constructed to have a closed-packed geometry that produces an azimuthal isotropic scattering of luminescence within a confined extraction angle cone. The confined extraction angle cone is uniquely defined by the aperiodic geometry of the array. Accordingly, changing various parameters associated with the aperiodic geometry of the array 120 affects the confined angle cone. For example, changing one or a combination of the scaling factor, the divergence angle (which can approach the golden angle), or the aspect ratio of the structures 100, the column height (h) 101, the column diameter (D) 103, or the mean spacing can <r>105 affect the restricted angle cone.

[0028] Fig. Figure 2 shows a block diagram of an exemplary lighting element 200 implementing an embodiment of the present disclosure. In general, the lighting element 200 comprises a light source 210, a phosphor layer 220, and the aperiodic array 120. In this example, the aperiodic array 120 is located on the phosphor layer 220. During operation, the light source 210 emits a beam of light into the phosphor layer 220, with part of the beam being converted into light of a different wavelength. The combination of the originally emitted light and the modified light often results in a spectral light distribution with a longer wavelength than the originally emitted light. For example, the light source 210 can be arranged to emit light (e.g., photons) 211 either in the blue light range or in the ultraviolet (UV) light range.Assuming the light source emits blue photons 211, these blue photons 211 can either pass through the phosphor layer 220 unchanged or they can be converted into photons 213, e.g., into the yellow light range. The combination of the blue photons 211 and the yellow photons 213 can together produce white light, which is emitted by the device 200. It should be noted that the present disclosure could be implemented with devices of the full-conversion type, or with those in which the pump light (e.g., all or almost all blue photons 211) is completely or substantially absorbed in the conversion layer (e.g., phosphor layer 220). The examples are not limited in these contexts.

[0029] The aperiodic array 120 is arranged or formed on the phosphor layer 220 and ensures that the photons 211 and 213 emitted by the aperiodic array 120 are confined to a specific angular cone. Further examples are given below. In general, the illumination element 200 can be any illumination element that uses phosphor to modify the wavelength of the output light beams. For example, the illumination element can be a phosphor-coated light-emitting diode (LED) or a laser-activated remote phosphor device (LARP). The examples are not limited in this context.

[0030] In some embodiments, the phosphor layer 220 can comprise a variety of phosphors. In the field of solid-state lighting, for example, the phosphor layer 220 can comprise a polymer matrix (e.g., silicone) with embedded powder phosphor grains, phosphor grains in a glass matrix (PiG), monolithic ceramic phosphors, monolithic single-crystal phosphors, various coatings and thin-film phosphors, including those produced by physical vapor deposition (PVD, e.g., pulsed laser deposition, PLD) and chemical vapor deposition (CVD) on transparent substrates, as well as other phosphor configurations.

[0031] It should be noted that applications with high luminance and / or high power may benefit from reduced étendue emission. Such applications typically require special phosphor conversion materials to improve heat dissipation and reduce the thermal quenching of the phosphor. In such cases, the phosphor platelet is typically a solid / monolithic polycrystalline ceramic phosphor (e.g., cerium-activated garnet phosphor, represented by the formula A3B5O12:Ce, where AY, Sc, La, Gd, Lu, or Tb and B is Al, Ga, or Sc). As a specific example, the phosphor layer 220 can be at least one of Y3Al5O12:Ce, (Y,Gd)3Al5O12:Ce, (Lu,Y)3Al5O12:Ce, and Lu3Al5O12:Ce. As another example, the phosphor layer could comprise 220 ceramic phosphor materials made of a different oxide, nitride, oxynitride, fluoride or similar.As another example, such ceramic phosphors can contain additional phases such as Al2O3 to change the scattering behavior, increase the thermal conductivity or achieve certain adhesive properties to the binder material.

[0032] In some embodiments, the phosphor layer 220 can contain other phosphors, such as various materials mentioned above, doped with other ions, e.g., Eu²⁺, Eu³⁺, Pr³⁺, Dy³⁺, or transition metal ions such as Mn²⁺, Mn⁴⁺, Cr³⁺, or the like. The dopant ions can be selected according to the wavelength of the pump (e.g., the light source 210). Such phosphor layers 220 can be provided in applications to achieve a wide range of color coordinates or spectral contents for the wavelength converter. The phosphor layer 220 can be formed by a number of techniques, including mixing the phosphor particles with an organic binder, shaping them into the desired form, and burning out the organic binder, followed by final high-temperature sintering to form a monolithic piece.The phosphor layer 220 can contain single-crystal ceramic or powdered phosphor embedded in various inorganic (e.g., such as a low-temperature glass) or numerous organic matrix materials. For example, a combination of phosphor powder and glasses with lower melting points (e.g., PiG or similar) can be used.

[0033] In some embodiments, the phosphor layer 220 could comprise a thin-film phosphor. Such phosphor layers 220 can enable excitation in the ultraviolet (UV) range and emission in the visible range. Additionally, such phosphor layers can incorporate quantum dots (QDs) in a variety of different matrix materials, from organic to inorganic. Such a phosphor layer 220 can be fabricated by a variety of methods (e.g., pulsed laser deposition (PLD), sputtering, ion beam, chemical vapor deposition (CVD), metal-organic CVD (MOCVD), or similar processes). These methods can facilitate the use of conversion materials such as InGaN, ZnO, AlInGaP, and a variety of other semiconductor materials that require an epitaxial film.

[0034] In some examples, the aperiodic array of structures (e.g., the aperiodic array 120 of structures 100) can have a geometry that resembles a Vogel spiral. Fig. 3A, Fig. 3B and Fig. 3C shows examples of aperiodic arrays of structures modeled on the Vogel's spiral. It is noted that Vogel's spirals are an example of possible aperiodic structures for controlling the directional properties of luminescence. Here, a number of examples of aperiodic structures exhibiting the geometry of a Vogel's spiral are presented. However, this should not be considered restrictive. In the case of a Vogel's spiral, which represents a subset of possible aperiodic structures for controlling the directional properties of luminescence from a thick phosphor, the aperiodic array (e.g., array 120) is formed from a number of columns (e.g., columns 100) arranged at the following coordinates: (rn,θn)=(an,n α) where n is a positive integer that names the number of the column, while a and α are constants.

[0035] In some examples, the golden angle (GA) Vogel spiral can be used. The GA Vogel spiral is deterministic and exhibits an isotropic filling of k-space within a desired ring-shaped region. An exemplary aperiodic array based on the GA Vogel spiral can be formed where α = 137.508° and the mean column (or array element) spacing is... <r>= 1.7a. Fig. Figure 3A shows an aperiodic array 321 having columns 301, where the mean center-to-center distance <r>between the columns 301 r mean = 450 nanometers (nm) and the diameter (D) of column 301 D = 226 nm. In Fig. 3B is an aperiodic array 322 represented, which has columns 302, where the mean center-to-center distance <r>between the columns 302 r mean = 380 nm and the diameter (D) of the column 302 D = 250 nm. In Fig. 3C is represented as an aperiodic array 323, which has columns 303 where the mean center-to-center distance <r>between the columns 303 r mean = 320 nm and the diameter (D) of the column is 303 D = 173 nm.

[0036] It is pointed out that the influence of an aperiodic array of structures (such as those in Fig. 1B, Fig. 3A, Fig. 3B and Fig. The angular cone of light emissions (as shown in Figure 3C) is influenced by the diffraction of the pattern of the aperiodic array, the effective directional or antenna properties of the individual columns in the aperiodic array, and the properties of the luminescent radiation within the phosphor plate that strikes the array. A discussion of such properties is provided in accordance with the present disclosure. As a starting point, it is assumed that each column is independent and that interactions between the columns are neglected. In other words, consider the aperiodic array as a phase amplitude mask for the incident light with a more general description of the radiation scattering properties of the columns. With this assumption, a theoretical description of the operation of the aperiodic array is given.This theory can be extended to approximately aperiodic arrays where the columns interact with each other. For example, assume that the scattering of the net incident field (e.g., the electric field component of the radiation) by a particular column consists of the superposition of the true incident field and the perturbation field generated by scattering at neighboring columns.

[0037] Using partial radiative coherence theory, it is assumed that the wavefront of the light directly behind the aperiodic array within the phosphor is a widely stationary random wavefront (i.e., the second-order statistics do not vary with position but are nevertheless spatially correlated). Under this assumption, the following formula for the scattered far-field radiative intensity / (u0) (W / sr) from the array can be derived. Radiative intensity is the power radiated into the air (or other output medium) per unit steradian. In the case of identical columns, the radiative intensity is: dPSCdΩ0=I(u0)≈∫|u| <kduk2S(u−u0)P(u0,u)LS(u)

[0038] Note that equation (2) assumes that the columns scatter strongly and are close enough together that specular transmission is low. This is essentially equivalent to the result that would be obtained using kinematic diffraction theory. Fig. 2 has the wavenumbers k0 = 2π n0 / λ0 and k = 2π n / λ0, where λ0 is the wavelength in free space and n is the refractive index of the phosphor. The variables u and u0 are the transverse components of the wave vectors k and k0, which are given by u = (u x ,u y ) = k(m x ,m y ), and where the directional cosine values ​​are given by: mx=uxk=sin θ cos ϕmy=Uyk=sin θ cos ϕmx=k2−−uy2k=cos θ

[0039] The analogous expressions apply to the directional cosines in the source medium with refractive index n0. Note that the radiance L S The net radiance is the light incident on the aperiodic array from the phosphor side. This net radiance can be the radiance resulting from multiple reflections / scattering from both the aperiodic array and the light source (e.g., LED, laser, etc.). In the case of Lambert's law, Ls would be a directionally constant radiance.

[0040] Based on scattering theory (i.e., single-scattering approximation), the scattering function P(u0, u) is related to the single-column scattering amplitude 2 x 2 tensor a(u0, u) by the following relationship: P(u0,u)=1mz(u)dσSCdΩ0=n0n1mz(u)k0212∑q0q|ε^q0(u0)⋅a__(u0,u)⋅ε^q(u)|2 Here, the factor P is closely related to the differential cross-section for the column, dσ. SC / dΩ0 is linked, while ℇ̂ q (u) and ℇ̂ q0 (u0) refer to the incident and scattered polarization vectors in the directions defined by u (or u0) with polarization q = s or p.

[0041] Fig. Figure 4 shows a diagram 400 with definitions of transverse wave vectors and propagation angles for the incident radiance distribution L S (u). This figure shows wave vectors (k) 401 propagating through a phosphor layer 220 and an aperiodic array 120. As shown, the aperiodic array 120 changes the propagation angle (θ) 403 of the wave vectors 401 as they enter the output medium 430 (e.g., air), which is described by the overall radiation distribution L S (u) is represented.

[0042] The structure factor S describes the Fourier power spectrum of the light diffracted by the aperiodic array of columns, represented as: S(u−u0)=|F(u−u0)|2=|F(u−u0)|2=|∑je−j(u0−u)⋅sj|2, where the vector s J The positions of the columns on the converter surface are specified. With reference to equation (2), it should be noted that the spectral power density S is integrated over all propagating transverse wave vectors u within the converting medium (e.g., the phosphor layer 220 or similar). Typically, the refractive index of the converting medium is greater than that of the emitting medium, which is typically air. Thus, the available transverse wave vectors u < k span a larger space than the available wave vectors u0 < k0 in the source medium. Assuming a high dispersion limit for the converted illuminant (e.g., illuminant 200 or similar), the incident radiance L can be S can be considered constant. It is noted that this is useful because Lambert's radiance approximation is often a limiting approximation for LARP or LED sources. Evaluating the scattering function for a column of height h and diameter D in a version of the anomalous diffraction approximation yields the following result: P(u0,u)=n0nξ(u0,u)mz(u)(Du0z / 2)2|u−u0|2|1−ej(np−1)k0h|2[J1(|u−u0|D2)] where n p the refractive index of the column (e.g., column 100 or similar), J I (x) is the first-order Bessel function and ξ(u0,u) is a slowly varying trigonometric function that takes into account the incident and scattered polarizations for a randomly polarized incident field. By further neglecting the far-field angular variation of the column scattering, P and L in equation (2) can both be treated as constants.

[0043] Fig. Figure 5 shows a diagram 500 illustrating an optimal structure factor S 501 for generating emission in a forward-direction component even for fully Lambertian light incident on the aperiodic array 120 from within the phosphor layer 220. As shown, when the spectrum of S 501 is made into a simple ring with radius k 401, the integral in Equation 1 is largest for emissions in the direction normal to the surface (u0 = 0) and decreases as u0 → k, since the overlap of the structure factor S decreases with the region of propagating waves in the phosphor layer 220. Thus, the structure factor S can take the form of the following equation. S=δ(|u|−k)

[0044] The theory presented above can be applied to construct an aperiodic array 120 that limits the emissions radiated by layer 220 within a desired cone. Fig. Figures 6A-6D and 7 illustrate the combined role that both the far-field scattering pattern of the array elements P and the array pattern given by the structure factor S have for the resulting limited emission cone.

[0045] Fig. Figure 6A shows a diagram 601 of a parameter space for a normalized radiance profile γ dn as a function of the outgoing emission with direction from the normal β' = |u0| / k0. It is noted that values ​​above one (1) indicate enhanced directional emission in the outgoing direction. In other words, diagram 601 of the parameter space illustrates the results of equation (2) for a GA Vogel spiral with Lambertian irradiation. As shown, for the free-space wavelength λ > 1.8, an angular ring structure forms in the far field; for λ < 1.8, the desired enhancement occurs closer to the perpendicular incidence.

[0046] Fig. Figure 6B shows a diagram 603 illustrating why equation (7) leads to the highest potential forward direction dependence, as described here. More precisely, diagram 603 illustrates the principle of light scattering at an isotropic k-space structure to enhance directional emission. Ring 603-A is a set of wave vectors propagating in the high-index medium (e.g., the phosphor layer 220 or similar), while ring 603-B represents the dominant feature of S(G). Each ring 603-C represents the set of input vectors scattered by a single array momentum vector G. Note that rings 603-C strongly overlap near the center but minimally near the edges, resulting in enhanced forward emission.The vectors indicate how a single incident wave vector β is phase-related with a momentum vector G to produce a scattered vector β' that is closer to the center of the light cone.

[0047] Fig. 6C and Fig. Figure 6D shows diagrams 605 and 607, respectively. These diagrams represent the structure factor S(G) for the extreme cases of enhanced forward scattering and wide-angle scattering, respectively. That is, these two figures represent the combination of the structure factor and the single-element scattering function at u = 0, S(u0)P(u0, 0), and show the ring structure of the far-field diffraction pattern of an aperiodic array (e.g., aperiodic array 120) formed according to the G.A. Vogel spiral. The solid white circle 609 indicates the boundary of the free-space light cone, while the dashed circle 611 indicates the boundary of the high-index light cone with n = 1.82.

[0048] Fig. Figure 7 shows a diagram 700, which presents a series of Fourier spatial images representing intensity profiles for a range of different emissions. Diagram 700 is divided into rows 710 and columns 720. The first row, 710-1, represents the described model; the second row, 710-2, represents measurements taken on a patterned region of a sample; and the third row, 710-3, represents measurements taken on an unpatterned region of the same sample. The columns 720 correspond to different patterns of aperiodic arrays with a column diameter of 410 nanometers (nm) and a height of 330 nm.Specifically, column 720-1 represents an aperiodic array with a mean nearest neighbor spacing of 220 nm, column 720-2 an aperiodic array with a mean nearest neighbor spacing of 300 nm, column 720-3 an aperiodic array with a mean nearest neighbor spacing of 380 nm, and column 720-4 an aperiodic array with a mean nearest neighbor spacing of 450 nm. The graph was generated from freestanding ceramic phosphor plates under laser excitation at 405 nm.

[0049] Each of the intensity profiles referenced in this figure (e.g., the intensity profile at [710-1, 720-1], etc.) features a white circle with a radius of 0.8, corresponding to the numerical aperture (NA) of the microscope objective used to generate the Fourier space images. It should be noted that the role of the radiance distribution L S (Light falling on the array of structures) is quite complex. In practical devices, the need for high light extraction without increasing the étendue usually requires that the illumination element (e.g., LED, laser, etc.) or the entire structure itself exhibits some degree of volume and / or surface scattering.

[0050] Typical lighting elements optimized for light extraction from the converted radiation (e.g., phosphor conversion devices as described here) provide a final radiance distribution incident on the aperiodic array mounted on the phosphor, closely following Lambert's law, as discussed in the example calculations with reference to equations (1) to (7). The radiation may also exhibit some degree of intensity gain due to cavity effects, ultimately leading to higher extraction efficiencies. For example, in the case of a LARP device, higher degrees of volume scattering are often necessary for good spot definition (high luminance).Although the present disclosure provides examples of light extraction for lighting elements where the distribution of incident light is close to the Lambertian distribution, this is not to be understood as a limitation, and components with aperiodic arrays, as described here, can also be provided for lighting elements where the distribution of incident light deviates significantly from the Lambertian distribution. In other words, aperiodic arrays, as described in . Fig. 1B and Fig. Figures 3A-3C can be used for components where the incident light distribution deviates significantly from the Lambertian distribution.

[0051] Accordingly, as described above, an aperiodic array exhibiting a pattern based on G.A. Vogel spirals can provide emission with controlled angular propagation. Going back to Fig. 1B can vary various parameters of the pattern of the aperiodic array 120, such as the height (h) 101 of the columns 100, the diameter (D) 103 of the columns 100 and the average distance between the columns. <r>105 can be manipulated to limit the emission within a desired angular cone. In some embodiments, these parameters can have the following ranges for luminescence wavelengths in the green to red visible range (i.e., 500–650 nm). 100 nm <h<1,000 nm100 nm<D<300 nm0.25λ0<〈r〉<2.5λ0

[0052] For luminescence wavelengths centered in the range near 550 - 570 nm, these parameters may have the following ranges in some embodiments. 300 nm <h<400 nm250 nm<D<350 nm380 nm<〈r〉<450 nm

[0053] In some embodiments, the height (h) can be restricted according to equation (6). For example, taking into account the phase delay accumulated by propagation through the column in equation (6), it follows that the maximum scattering occurs when the field generated by the column is in phase with the incident field in the air, resulting in the following: (nP−1)k0h=π,3π,… or, hopt≈λ02(nP−1)(2l+1),l=0,1,…

[0054] In the case of λ0 = 550 nm and a column made of TiO2 with n p The optimal height for ℓ = 0 and ℓ = 1 would be given by h = 196 nm and 589 nm, respectively. It should be noted that the first value is slightly shorter than the optimal heights listed above (which can be determined from FDTD simulations and experiments). However, the optimal heights from equations (10) and (11) are a useful starting point for constructing an aperiodic array 120. In some examples, the construction approach can be reversed using the following equation. (nP−1)k0h=2π,4π,… Equation (12) can provide a maximum backscattering which may be useful for designing an aperiodic array where a range of wave vectors is excluded by the aperiodic array from being back-reflected into the phosphor layer 220.

[0055] Similarly, the optimal column diameter can be estimated, for example, from equation (6). It should be noted that the dependence of the diameter D on a term of the form x 2 J1(x), x = |u - u0| D / 2 originates. In some examples, the emission can be maximized with normal emission (θ0 = 0). Taking the optimal condition from the structure factor as u ≈ k, it follows that (kD / 2) 2 J1(kD / 2) is to be maximized, which has a maximum when: D≈2×2.7272πnλ0 For example, D = 260 nm for a monolithic ceramic phosphor (n = 1.83) and λ0 = 550 nm. The above examples can be extended to design or optimize the column height and diameter to create aperiodic patterns for other converting materials, emission wavelengths, or similar conditions. The examples are not limited in this respect.

[0056] An aperiodic array can be constructed or designed and then manufactured as described above. Fig. Figure 8 shows, for example, a logical sequence 800 for creating an aperiodic array according to some examples from the revelation. Fig. Figures 9A-9H show an example of an aperiodic array during different manufacturing stages. These figures are presented in conjunction with the schematic sequence 800 from Fig. 8 discussed.

[0057] The schematic sequence 800 can begin with block 810 “Applying a dielectric to a phosphor layer”, in which the dielectric is applied to a phosphor layer. Fig. Figure 9A shows, for example, the dielectric 901 applied to the phosphor layer 220. In some embodiments, the dielectric 901 can consist of titanium oxide (TiO2). TiO2 can be deposited, for example, (e.g., by sputtering or similar processes) onto a cerodoped yttrium aluminum garnet (Ce:YAG) or similar phosphor layers. As a specific example, TiO2 can be deposited by DC sputtering under a base pressure (66.6% Sccm argon + 33.3% Sccm O2) of 2.5 m Torr. The TiO2 target has a purity of 99.998% and a diameter of 3 inches. The target-substrate distance can be set to 10 cm. Furthermore, in some examples, a periodic movement of 5 rpm of the substrate (e.g., the phosphor layer 220) is applied during deposition. As another example, TiO2 can be deposited onto a pre-cleaned Ce:YAG substrate by magnetron sputtering with a DC power of 240 W.In some embodiments, the phosphor layer 220 can be cleaned (e.g., before deposition) to remove impurities. For example, the phosphor layer 220 can be cleaned by sonication with acetone and ethanol for a specific period (e.g., 5–15 minutes). As another example, the phosphor layer 220 can be cleaned by oxygen etching, e.g., at 300 W with a flow rate of 150 sccm for a specific time (e.g., 2.5 to 10 minutes).

[0058] Continuing from block 820 “Applying a photoresist over the dielectric”, a photoresist is applied to the dielectric. Fig. Figure 9B shows, for example, the photoresist 903 applied to the dielectric 901. In some embodiments, the photoresist 903 can be a polymer photoresist based on polymethyl methacrylate (PMMA) that can be spin-deposited onto the dielectric 901. Moving on to Block 830, “Exposing the Photoresist with Electron Beam Lithography,” the photoresist can be exposed using electron beam lithography (EBL) to modify the solubility of parts of the photoresist. Fig. Figure 9C shows, for example, the photoresist 903 exposed to the EBL 905. As a specific example, the photoresist 903 can be exposed to EBL 905 at a dose of 200 µC / cm² and a current of 36–37 pA. Moving on to Block 840, “Developing the exposed photoresist,” the photoresist layer can be developed, for example, in a solvent to make the exposed pattern visible. Fig. Figure 9D shows, for example, portions of the photoresist 903 that have been dissolved in a solvent to make a pattern visible. It is noted that the portions of the photoresist 905 exposed to the EBL 905 change their solubility in a solvent (e.g., acetone, isopropyl alcohol (IPA), isomethyl butyl ketone (IMBK), or a combination thereof) and are therefore dissolved during development (e.g., in block 840), while the unexposed portions of the photoresist 903 remain undissolved and expose portions of the dielectric 901.

[0059] Following on from block 850 “Masking the photoresist and the dielectric”, a mask can be placed over the photoresist and the exposed dielectric. Fig. Figure 9E shows, for example, the mask 907, which is applied over the structured photoresist 903 and the exposed parts of the dielectric 901. In some embodiments, the mask can be made of chromium (Cr). In the further course of section 860 “Removing the photoresist”, the photoresist can be removed so that only parts of the dielectric remain masked. Fig. For example, 9F shows that the photoresist 903 has been removed and only parts of the dielectric 901 are masked with the mask 907. In the further course of block 870 “Etching the Dielectric”, the dielectric can be etched, e.g. by reactive ion etching (RIE) or similar methods. Fig. 9G shows, for example, the dielectric 901, which was etched using RIE 909 to form dielectric columns 100.

[0060] Continuing from Block 880 “Removing the Mask”, the mask can be removed from the dielectric to form the finished aperiodic array. Fig. Figure 9H shows, for example, an aperiodic array 120 comprising the dielectric columns 100 formed on the phosphor layer 220. It should be noted that an aperiodic array (e.g., the aperiodic array 120 or similar) can be formed using the lithographic process described herein or using other nanostructure fabrication methods, such as DUV lithography, nano-imprinting, three-dimensional (3D) printing, or similar techniques. The examples are not limited in this context.

[0061] It is noted that in some examples the columns for an aperiodic array 120 could be formed directly from a converting layer, as opposed to a dielectric, as in Fig. 8 and Fig. Figures 9A-9H are presented and discussed. With regard to procedure 800, for example, step 810 could be omitted, and a photoresist could be applied directly to the phosphor layer 220 in step 820. The fabrication could then proceed as discussed or using other techniques to form the columns 100 of the aperiodic array 120 directly from the phosphor layer 220. The examples are not limited in this context.

[0062] Back to Fig. 2: As shown, some embodiments provide a phosphor layer 220 which is excited from the rear by a light source 210, while the aperiodic array 120, arranged on the front of the phosphor layer 220, restricts the light emission to a specific emission cone. Diagram 700 of Fig. Figure 7, which depicts Fourier spatial images, is derived from such an embodiment. In particular, the ceramic layer 220 was a freestanding ceramic phosphor excited from the back side by a laser at 405 nm. In general, the excitation wavelength of the pump source 210 can coincide with the absorbing excitation band of the luminescent material. Fig. Figure 7 shows the first row, 710-1, an approximation of theoretical calculations similar to equation (2) for a Vogel spiral and Lambertian irradiance (Ls = constant). Since luminescence is typically produced by isotropically emitting radiators, the generation of Lambertian incident light requires some volume and / or surface scattering. Experimental measurements of the far-field angular distribution in rows 710-2 and 710-3 were performed using the k-space measurement scheme. As described above, columns 720 correspond to the different average column spacings. As shown, the far-field pattern changes from a ring type to a central, localized enhancement with increasing column spacing, since the radius of the main ring in the structure factor of the aperiodic array 120 (e.g. Vogel's spiral or similar) changes from a value above the propagating waves in the phosphor layer 220 to a value approximately equal to k (see e.g.Equation (7)). It is noted that both the experimental data (line 710-2) and the approximate theoretical calculations (line 710-1) show good qualitative agreement.

[0063] To verify that the experimental results are not measurement artifacts, series 710-3 shows the same plates excited with 405 nm light, but outside the array. The faint ring structure observed at the periphery is consistent with the emission of converted light in transparent phosphors with low scattering. As shown from Fig. As can be seen in Figure 7, the optimal average column spacing for most forward-directed light lies in the range <r>= 380 nm - 450 nm.

[0064] Fig. 10A, Fig. 10B and Fig. Section 10C shows diagrams representing different experimental variations of the parameters of an aperiodic array. Note that each of the diagrams shows the radiance γ. dn the outgoing emission is represented as a function of the normalized directional dependence of the emission β' / k0. Fig. Figure 10A, for example, shows graph 1001, which shows the varying diameter (D) 103 of the columns 100 in the aperiodic array 120 with a fixed mean spacing. <r>= 450 nm. As can be seen, the column diameter of 103 has a minimal effect on the directivity, with a maximum at 250 nm < D < 280 nm. Fig. Figure 10B shows diagram 1002, which illustrates the dependence of radiance on the mean column spacing. <r>shows, with a maximum directivity at <r>= 380 nm is reached. A directional improvement of up to 35% is observed in the forward direction when <r>from 220 nm to 450 nm. Note that graphs 1001 and 1002 were obtained from experimental data using a freestanding ceramic LuAG phosphor plate, which may not exhibit full irradiation in the phosphor according to Lambert's law. Fig. Figure 10C shows diagram 1003, which illustrates the theoretically modeled directional improvement compared with the experimental diagrams 1002 from Fig. 10B matches.

[0065] Fig. Figure 11 shows a block diagram of an exemplary lighting element 1100 implementing an embodiment of the present disclosure. In general, the lighting element 1100 comprises a light source 210, a phosphor layer 220, the aperiodic array 120, and a dichroic layer 1130. As shown, the dichroic layer 1130 is arranged on a back side of the phosphor layer 220, while the aperiodic array 120 is arranged on a top or front side of the phosphor layer 220. During operation, the light source 210 emits a beam of light (photons 211) into the phosphor layer 220, thereby exciting the phosphor layer 220 and causing the emission of photons 213. The dichroic layer 1130 is arranged such that it transmits or allows light of the wavelength emitted by the light source 210 (e.g. blue light or similar) to pass through, while reflecting other, longer wavelength light (e.g. yellow light or similar).The phosphor layer 220 emits photons 213 from both its front and back surfaces. However, due to the dichroic layer 1130, the photons 213 are reflected back into the phosphor layer 220. It should be noted that the light emitted by the phosphor layer 220 (e.g., photons 213, etc.) can undergo significant scattering, and therefore the radiance distribution behind the array (Ls) generally approximates Lambert's law. The loss of directional properties in the radiation distribution can reduce the directional effects of the light emitted from the aperiodic array 120 into the output medium (e.g., air, etc.). However, the specific spectral properties of the aperiodic array 120 provide greater tolerance to the incident radiation distribution than other configurations (e.g., periodic arrays, lenses, etc.).

[0066] Fig. Figure 12 shows a block diagram of an exemplary lighting element 1200 implementing an embodiment of the present disclosure. In general, the lighting element 1200 comprises a forward-emitting LED 1240 formed on a substrate 1210 and having an LED reflector 1241 arranged on a rear side of the forward-emitting LED 1240, as well as an LED extraction layer 1242 arranged on a top side of the forward-emitting LED 1240. A phosphor layer 220 is attached directly to the top side (e.g., LED extraction layer 1242) of the forward-emitting LED 1240 via a bonding layer 1250 (e.g., adhesive film or the like). The aperiodic array 120 is arranged on the top side of the phosphor layer 220. The configuration shown in this figure can typically be referred to as a chip-level conversion (CLC) device.The LED 1240 can be a blue-emitting InGaN LED, comprising the LED reflector 1241 and the LED extraction layer 1242 (e.g., with a highly roughened surface or similar). The phosphor layer 220 can be a ceramic phosphor (e.g., PiG, or one of the many other phosphor layers discussed here).

[0067] During operation, the pump light 1201 from the LED 1240 is partially or completely absorbed in the phosphor layer 220. Converted light 1203 (e.g., luminescence) is emitted isotropically by the activator ions or other emitting centers (such as quantum dots or color centers) within the composition of the phosphor layer 220. Surface scattering and volume scattering within the phosphor modify the radiance distribution within the phosphor that strikes the emitting surface covered by an aperiodic array. This final radiance distribution within the phosphor, striking the array, determines the net angular emission profile into the output medium (e.g., air). Volume scattering within the phosphor layer 220 can be generated by pores, phosphor particles, or additional material phases, grain boundaries, and other scattering centers (refractive index contrast levels) that can be introduced into the phosphor layer 220.

[0068] This figure further shows a polar diagram (dashed line) of a conventional far-field radiation intensity distribution 1205, which is typical for the surface of a phosphor layer with an unstructured surface. Additionally, this figure shows a diagram (dash-dotted line) of a pattern far-field radiation intensity distribution 1207 generated by the aperiodic array 120, which has a narrower profile than the conventional distribution 1205. It should be noted that on the underside of the phosphor layer 220 (e.g., on the LED side 1240 of the phosphor layer 220), surface scattering results from the net effect of the interface between the compound layer 1250, the LED extraction layer 1242, and the LED reflector 1241. It should be noted that diagrams 1205 and 1207 are plotted against the polar axis 1209.

[0069] In general, the pump light 1201 emerging from the phosphor layer 220 will have a different internal radiation distribution than the converted light 1203. In some embodiments, the aperiodic array 120 can be configured or arranged to control the angular profile of both the converted light 1203 and the pump light 1201. In other words, since the phase response and far-field scattering of the columns 100 within the aperiodic array 120 are wavelength-dependent, an aperiodic array 120 could be designed to influence both the pump light 1201 and the converted light 1203.

[0070] Fig. Figure 13 shows a block diagram of an exemplary illumination element 1300 implementing an embodiment of the present disclosure. In general, the illumination device 1300 comprises a laser pump device 1340 arranged to emit pump light 1301 directed onto a phosphor layer 220 with an aperiodic array 120 arranged on the phosphor layer 220. The phosphor layer 220 is arranged on a transparent substrate 1350 via a bonding layer 1351 (e.g., adhesive or the like). In some examples, the laser pump device 1340 may be a focused or closely spaced blue diode laser. The illumination element 1300 further comprises secondary optics 1360 (e.g., a collimating lens or the like) arranged downstream of the laser pump device 1340 and the phosphor layer 220 in the beam direction.The illumination element 1300 is often referred to as a laser-activated, side-facing component (LARP). Such a LARP component can have either a reflective geometry (pump light falls onto the phosphor from the side of the aperiodic array, not shown in this figure) or a transparent geometry (shown in this figure). The phosphor layer 220 can be a ceramic phosphor (e.g., PiG or one of the many other phosphor layers described here).

[0071] During operation, the aperiodic array 120 restricts the angular emission of the far-field pattern, allowing the secondary optics 1360 to collect more converted light 1303 and pump light 1301 within its numerical aperture compared to light from a surface without an aperiodic array. In general, the pump light 1301 emitted from the phosphor layer 220 will have a different internal radiation distribution than the converted light 1303 and can therefore be controlled differently by the aperiodic array 120 to achieve the desired effects. Here, as in Fig. 12, the aperiodic array 120 can be designed to control the angular emission of the pump light 1301 in addition to the converted light 1303. It should be noted that the illumination element 1300 can optionally include a dichroic layer, although it is not shown in this figure. For example, the dichroic layer could be arranged on the phosphor layer 220 or on the transparent substrate 1350.

[0072] Various aspects disclosed herein include an illumination element with a light source for emitting a first beam of light with a wavelength within a first wavelength range, a converting material arranged such that the beam of light is incident on the converting material, wherein the converting material emits a second beam of light with a wavelength within a second wavelength range, the second wavelength range being different from the first wavelength range, and an aperiodic array arranged on the converting material, wherein the aperiodic array comprises a plurality of columns arranged to form an aperiodic pattern, the aperiodic array restricting the emission of the second beam of light to a limited angular cone.

[0073] In some embodiments, the aperiodic array comprises a circularly symmetric Fourier k-space to generate azimuthal isotropic scattering of the luminescence within the bounded angular cone. In some embodiments, the plurality of columns forms a Vogel's spiral. In some embodiments, the plurality of columns forms a golden-angle Vogel's spiral. In some embodiments, the converting material comprises phosphor. In some embodiments, the converting material has the composition A3B5O12:Ce, where A is selected from the group consisting of Y, Sc, La, Gd, Lu, or Tb, and B is selected from the group consisting of Al, Ga, or Sc. In some embodiments, the second wavelength range lies between 500 nanometers and 600 nanometers. In some embodiments, the light source is a light-emitting diode (LED).In some embodiments, the first wavelength range is between 430 nanometers and 495 nanometers or between 375 nanometers and 410 nanometers. In some embodiments, the converting material is arranged on a top surface of the LED. In some embodiments, the light source is a laser. In some embodiments, the illumination element further comprises a collecting optic arranged downstream of the converting material. In some embodiments, the mean center-to-center spacing between each of the plurality of columns is between 300 and 500 nanometers. In some embodiments, each of the plurality of columns has a height between 100 nanometers and 1,000 nanometers. In some embodiments, each of the plurality of columns is cylindrical and has a diameter between 100 nanometers and 300 nanometers.

[0074] Other aspects described herein include an aperiodic array to confine illumination emissions within an angular cone, wherein the aperiodic array comprises a substrate and a plurality of dielectric pillars arranged on the substrate and forming an aperiodic array, the plurality of dielectric pillars working together to produce an azimuthal isotropic scattering of the incident luminescence within a confined angular cone.

[0075] In some embodiments, each of the plurality of dielectric columns contains a transparent dielectric. In some embodiments, each of the plurality of dielectric columns comprises titanium dioxide (TiO₂), titanium nitride (TiN), silicon (Si), silicon nitride (SiN), or doped oxides. In some embodiments, the aperiodic array is a Vogel's spiral. In some embodiments, the mean center-to-center distance between each of the plurality of columns is between 0.25 and 2.5 times the wavelength of the incident luminescence. In some embodiments, each of the plurality of columns is cylindrical, conical, pyramidal, or rectangular in shape. In some embodiments, each of the plurality of columns is cylindrical and has a height between 100 nanometers and 1,000 nanometers and a diameter between 100 nanometers and 300 nanometers. In some embodiments, the substrate comprises a phosphor.

[0076] Other aspects disclosed herein include a method for producing an aperiodic array to confine illumination emissions within an angular cone, the method comprising applying a pattern for marking a plurality of columns arranged in an aperiodic array onto a substrate containing a converting material arranged to emit light of a first wavelength in response to the incident light of a second, different wavelength, and forming the plurality of columns from the substrate.

[0077] In some embodiments, the method further comprises depositing a dielectric material into the wavelength-converting material and etching the dielectric material to form the plurality of columns. In some embodiments, the aperiodic array is a Vogel's spiral. In some embodiments, each of the plurality of columns is cylindrical and has a height between 100 nanometers and 1,000 nanometers and a diameter between 100 nanometers and 300 nanometers, and a mean center-to-center distance between each of the plurality of columns is between 0.25 and 2.5 times the first wavelength.

[0078] Some embodiments may be described using the phrase "an embodiment" together with its derivatives. These terms mean that a feature, structure, or property described in relation to the embodiment is included in at least one embodiment. The appearance of the phrase "in an embodiment" at different points in the description does not necessarily refer to the same embodiment. Furthermore, some embodiments may be described using the terms "coupled" and "connected" and their derivatives. These terms are not necessarily synonymous. For example, some embodiments may be described using the terms "connected" and / or "coupled" to indicate that two or more elements are in direct physical or electrical contact with each other.The term "coupled" can also mean that two or more elements are not in direct contact with each other, but nevertheless cooperate or interact. Furthermore, aspects or elements from different embodiments can be combined.

[0079] It is emphasized that the summary of disclosure is provided to enable the reader to quickly grasp the nature of the technical disclosure. It is presented with the understanding that it is not to be used for the interpretation or limitation of the scope or meaning of the claims. Furthermore, in the foregoing description, various features in a single embodiment are grouped together to simplify the disclosure. This method of disclosure is not to be understood as meaning that the claimed embodiments require more features than are expressly listed in the individual claims. Rather, as the following claims demonstrate, the subject matter of the invention lies in fewer than all the features of a single disclosed embodiment. Therefore, the following claims are hereby incorporated into the description, each claim constituting a separate embodiment.In the attached claims, the terms "comprising" and "whereby" are used as simple equivalents of the respective concepts "comprising" and "whereby". Furthermore, the terms "first", "second", "third", etc. are used merely as designations and are not intended to impose numerical requirements on their objects.< / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r> < / r>

Claims

[1] A lighting element (200), comprising a light source (210) for emitting a first beam of light having a wavelength within a first wavelength range; a converting material arranged in a phosphor layer (220) such that the light beam is incident on the converting material, wherein the converting material emits a second light beam with wavelengths within a second wavelength range, the second wavelength range being different from the first wavelength range and having wavelengths from 500 nm to 650 nm; and a dielectric aperiodic array (120) arranged on the phosphor layer (220), wherein the dielectric aperiodic array (120) comprises a plurality of dielectric scattering columns (100) that are smaller than the wavelength of the light and are arranged to form an aperiodic pattern, and wherein the dielectric aperiodic array (120) is configured to produce an azimuthal isotropic scattering of the incident luminescence within a limited angular cone (1207) such that more than 85% of the total generated light emission is emitted into an angular cone of ± 60°, wherein the angular cone of ± 60° corresponds to an angular cone into which the phosphor layer (220) emits 75% of the total generated light emission, and wherein the phosphor layer (220) is unstructured and optically thick. [2] Lighting element (200) according to claim 1, wherein the plurality of dielectric scattering columns (100) form a Vogel's spiral. [3] Lighting element (200) according to claim 2, wherein the plurality of dielectric scattering columns (100) form a Vogel spiral with golden angle. [4] Lighting element (200) according to claim 1, wherein the converting material has the composition A3B5O 12:Ce, where A is selected from the group consisting of Y, Sc, La, Gd, Lu or Tb and B is selected from the group consisting of Al, Ga or Sc. [5] Lighting element (200) according to claim 1, wherein the light source (210) is a light-emitting diode (LED). [6] Lighting element (200) according to claim 5, wherein the first wavelength range is between 430 nanometers and 495 nanometers or between 375 nanometers and 410 nanometers. [7] Lighting element (200) according to claim 1, wherein the light source (210) is a laser. [8] Lighting element (200) according to claim 7, which further comprises a collecting optic (1360) which is arranged downstream of the converting material in the direction of the beam. [9] Lighting element (200) according to claim 1, wherein a mean center-to-center distance (105) between each of the plurality of columns (100) is between 300 and 500 nanometers. [10] Lighting element (200) according to claim 1, wherein each of the plurality of columns (100) has a height (101) between 100 nanometers and 1,000 nanometers. [11] Lighting element (200) according to claim 1, wherein each of the plurality of columns (100) is cylindrically shaped and has a diameter (103) between 100 nanometers and 300 nanometers. [12] An arrangement encompassing, a substrate that is a phosphor layer (220), wherein the phosphor layer (220) is unstructured and optically thick and is configured to generate light in a wavelength range of 500 nm to 650 nm, and a plurality of dielectric scattering columns (100) that are smaller than the wavelength of the light and that are arranged on the substrate such that they form a dielectric aperiodic array (120) with an aperiodic pattern, wherein the plurality of dielectric scattering columns (100) of the aperiodic pattern interact to produce an azimuthal isotropic scattering of the incident luminescence within a limited angular cone (1207), such that more than 85% of the total generated light emission is emitted into an angular cone of ± 60°, wherein the angular cone of ± 60° corresponds to an angular cone into which the phosphor layer (220) emits 75% of the total generated light emission. [13] Arrangement according to claim 12, wherein each of the plurality of dielectric scattering columns (100) comprises a transparent dielectric. [14] Arrangement according to claim 13, wherein each of the plurality of dielectric scattering columns (100) comprises titanium dioxide (TiO2), titanium nitride (TiN), silicon (Si), silicon nitride (SiN) or doped oxides. [15] Arrangement according to claim 13, wherein the dielectric aperiodic array is a Vogel spiral. [16] Arrangement according to claim 15, wherein a mean center-to-center distance (105) between each of the plurality of dielectric scattering columns (100) is between 0.25 and 2.5 times the wavelength of the incident luminescence. [17] Arrangement according to claim 15, wherein each of the plurality of dielectric scattering columns (100) is cylindrical, conical, pyramidal or rectangular in shape. [18] Arrangement according to claim 15, wherein each of the plurality of dielectric scattering columns (100) is cylindrically shaped and has a height (101) between 100 nanometers and 1000 nanometers and a diameter (103) between 100 nanometers and 300 nanometers. [19] Method for manufacturing an arrangement, the method comprising: Applying a pattern for marking a plurality of dielectric scattering columns (100) smaller than the wavelength of light and arranged in a dielectric aperiodic array (120) onto a substrate comprising a converting material arranged in a phosphor layer (220) and arranged to emit light with first wavelengths of 500 nm to 650 nm in response to the incident of light of a second, different wavelength, and Formation of the multitude of dielectric scattering columns (100), which are smaller than the wavelength of the light, on the substrate, wherein the phosphor layer (220) is unstructured and optically thick, wherein the pattern of the plurality of dielectric scattering columns (100) which are smaller than the wavelength of the light is arranged such that it produces an azimuthal isotropic scattering of the incident luminescence within a limited angular cone (1207) such that more than 85% of the total generated light emission is emitted into an angular cone of ± 60°, wherein the angular cone of ± 60° corresponds to an angular cone into which the phosphor layer (220) emits 75% of the total generated light emission. [20] The method of claim 19, further comprising: Deposition of a dielectric material into the wavelength-converting material; and Etching of the dielectric material to form the multitude of dielectric scattering columns (100). [21] Method according to claim 19, wherein the dielectric aperiodic array (120) is a Vogel spiral. [22] Method according to claim 19, wherein each of the plurality of dielectric scattering columns (100) is cylindrically shaped and has a height (101) between 100 nanometers and 1,000 nanometers and a diameter (103) between 100 nanometers and 300 nanometers, and wherein a mean center-to-center distance (105) between each of the plurality of dielectric scattering columns is between 0.25 and 2.5 times the first wavelength.

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