Light guide comprising KSIF phosphor particles for light conversion and blue light extraction

Abstract

The invention provides a light generating system (1000) comprising a light generating device (110) and a light guide arrangement (400), wherein: - the light generating device (110) is configured to generate device light (111); - the light guide arrangement (400) comprises a light in-coupling area (401), a first dimension (D1), a second dimension (D2), and a light out-coupling area (402) over at least part of the first dimension (D1); wherein D2 / D1≤0.1; - the light in-coupling area (401) is configured in a light receiving relationship with the light generating device (110); - the light guide arrangement (400) comprises a first luminescent material (210); wherein the first luminescent material (210) comprises a luminescent material of the type M'xM2-2xAX6:Mn4+; wherein the first luminescent material (210) is configured to convert at least part of the device light (111) downstream from the light in-coupling area (401) into first luminescent material light (211); - the light guide arrangement (400) comprises a first particulate material (431) embedded in a first light transmissive material (420) over at least part of the first dimension (D1); wherein the first particulate material (431) comprises at least part of the first luminescent material (210); and - the first luminescent material (210) is distributed over at least part of the first dimension (D1) such that during operation of the light generating device (110), first luminescent material light (211) is generated and emanates from the light out-coupling area (402) of the light guide arrangement (400) over at least part of the first dimension (D1).

Description

[0001] 2024PF80431

[0002] 1

[0003] LIGHT GUIDE COMPRISING KSIF PHOSPHOR PARTICLES FOR LIGHT CONVERSION AND BLUE LIGHT EXTRACTION

[0004] FIELD OF THE INVENTION

[0005] The invention relates to a light generating system and to a lighting device comprising such light generating system.

[0006] BACKGROUND OF THE INVENTION

[0007] Light generating systems are known in the art. US2023174862A1, for instance, describes light emitting devices and LED-filaments comprising an excitation source (e.g. LED) and a photoluminescence material comprising a combination of a first narrowband red photoluminescence material which generates light with a peak emission wavelength in a range 580 nm to 628 nm and a full width at half maximum emission intensity in a range 45 nm to 60 nm and a second narrow-band red photoluminescence material generates light with a peak emission wavelength in a range 628 nm to 640 nm and a full width at half maximum emission intensity in a range 5 nm to 20 nm.

[0008] WO2019 / 136832A1 discloses a light source apparatus having a light guide. The light guide comprises a transparent tube and a light guide medium provided in the transparent tube. The light guide medium comprises a binding material and fluorescent powder, with the distance between the binding material and the transparent tube being less than 780 nm. By choosing a binding material and a transparent tube with similar refractive indexes, a slurry containing the fluorescent powder and the binding material is cured in the transparent tube. An outer wall of the transparent tube is used as a side face of the light guide.

[0009] SUMMARY OF THE INVENTION

[0010] Conventional light generating systems (e.g. incandescent or fluorescent lamps) are rapidly being replaced by light emitting diode (LED) based lighting solutions. LED-based lighting solutions may generally comprise a light source and a luminescent converter, wherein the luminescent converter may comprise multiple types of phosphors, such as a yellow and a red phosphor, to produce light with a suitable color or color temperature. Prior art systems may make use of narrow-band fluoride red phosphors. However, due to their2024PF80431

[0011] 2

[0012] intrinsic hygroscopic nature, these phosphors may degrade over time due to contact with moisture, thereby reducing the lifetime of the light generating system and / or causing a change in optical properties of the system light over time. Further, known LED-based lighting solutions may suffer from low lumen per Watt efficiency, which may increase energy consumption by consumers. Yet further, prior art solutions may have problems with self-absorption in the phosphor layer, wherein light emitted by a first type of phosphor is absorbed by a second type of phosphor, thereby reducing the efficiency of the system and altering one or more of the correlated color temperature (CCT), color rendering index (CRI), and color point of the system light. As such, there appears to be a desire for light generating systems that may especially be efficient and have stable (moisture-resistant) spectral properties. Especially, it may be desired to provide a light generating system based on narrow-band fluoride red phosphors with high luminous efficiency, high color quality, and improved stability of the phosphor. Hence, it is an aspect of the invention to provide an alternative light generating system, which preferably further at least partly obviates one or more of above-described drawbacks. The present invention may have as object to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0013] According to a first aspect, the invention provides a light generating system comprising a light generating device and a light guide arrangement. Especially, the light generating device may be configured to generate device light having a device light centroid wavelength (λdc). In embodiments, the device light centroid wavelength (λdc) may be selected from the range of 380-490 nm. In embodiments, the light generating device may comprises a semiconductor-based light generating device. Further, in embodiments the light guide arrangement may comprise a light in-coupling area, a first dimension (DI), a second dimension (D2), and a light out-coupling area over at least part of the first dimension (DI). In embodiments, the first dimension (DI) may be a length. Further, in embodiments the second dimension (D2) may be a circular equivalent diameter of a cross-sectional area defined perpendicular to the first dimension (DI). In specific embodiments, D2 / D1≤0.1. Yet, in embodiments, the light in-coupling area may be configured in a light receiving relationship with the light generating device. Further, in embodiments, along at least part of the first dimension (DI) of the light guide arrangement downstream of the light in-coupling area, the light guide arrangement may be at least partly transmissive for the device light coupled into the light guide arrangement via the light in-coupling area. In embodiments, the light guide arrangement may comprise a luminescent material. Especially, the light guide arrangement2024PF80431

[0014] 3

[0015] may comprise a first luminescent material. In embodiments, the first luminescent material may comprise, more especially may be, a luminescent material of the type M’XM2-2XAXe: Mn4+, wherein M’ comprises an alkaline earth cation, M comprises a monovalent cation, and x is in the range of 0-1, wherein A comprises a tetravalent cation, comprising one or more of silicon, titanium, and germanium, wherein X comprises a monovalent anion, at least comprising fluorine. Further, especially the first luminescent material may be configured to convert at least part of the device light downstream from the light in-coupling area into first luminescent material light. In specific embodiments, the first luminescent material light may have a first centroid wavelength (λc1) selected from the range of 610-650 nm. Further, in specific embodiments the first luminescent material light may comprise at least one emission band having a first full width at half maximum FWHM1 of ≤ 45 nm. Yet, in embodiments the light guide arrangement may comprise a first particulate material embedded in a first light transmissive material over at least part of the first dimension (DI). Especially, in embodiments the first particulate material may comprise at least part of the first luminescent material. Yet, in specific embodiments the first particulate material may have a difference in refractive index with respect to the first light transmissive material of at least 0.1, though other embodiments may also be possible. Especially, in embodiments the first luminescent material may (thus) be distributed over at least part of the first dimension (DI). Yet, the first luminescent material may (thus) be distributed over at least part of the first dimension (DI) such that during operation of the light generating device, first luminescent material light may be generated and may emanate from the light out-coupling area of the light guide arrangement over at least part of the first dimension (DI). Hence, in embodiments the invention provides a light generating system comprising a light generating device and a light guide arrangement, wherein: (A) the light generating device is configured to generate device light having a device light centroid wavelength (λdc) selected from the range of 380-490 nm; wherein the light generating device comprises a semiconductor-based light generating device; (B) the light guide arrangement comprises a light in-coupling area, a first dimension (DI), a second dimension (D2), and a light out-coupling area over at least part of the first dimension (DI); wherein the first dimension (DI) is a length, and wherein the second dimension (D2) is a circular equivalent diameter of a cross-sectional area defined perpendicular to the first dimension (DI); wherein D2 / D1≤0.1; (C) the light in-coupling area is configured in a light receiving relationship with the light generating device; wherein along at least part of the first dimension (DI) of the light guide arrangement downstream of the light in-coupling area, the light guide arrangement is at least partly transmissive for the2024PF80431

[0016] 4

[0017] device light coupled into the light guide arrangement via the light in-coupling area; (D) the light guide arrangement comprises a first luminescent material; wherein the first luminescent material comprises a luminescent material of the type M’xM2-2xAX6: Mn4+, wherein M’ comprises an alkaline earth cation, M comprises a monovalent cation, and x is in the range of 0-1, wherein A comprises a tetravalent cation, comprising one or more of silicon, titanium, and germanium, wherein X comprises a monovalent anion, at least comprising fluorine; wherein the first luminescent material is configured to convert at least part of the device light downstream from the light in-coupling area into first luminescent material light, wherein the first luminescent material light has a first centroid wavelength (λc1) selected from the range of 610-650 nm, wherein the first luminescent material light comprises at least one emission band having a first full width at half maximum FWHM1 of ≤ 45 nm; (E) wherein the light guide arrangement comprises a first particulate material embedded in a first light transmissive material over at least part of the first dimension (DI); wherein the first particulate material comprises at least part of the first luminescent material; and (F) wherein the first particulate material has a difference in refractive index with respect to the first light transmissive material of at least 0.1; and (F) wherein the first luminescent material is distributed over at least part of the first dimension (DI) such that during operation of the light generating device, first luminescent material light is generated and emanates from the light out-coupling area of the light guide arrangement over at least part of the first dimension (DI).

[0018] With such light generating system, light may be generated over a relatively large length and / or a relatively large area. Further, with such light generating system, the light guide may be used both to distribute the light over a relatively large length and / or a relatively larger area, while also providing luminescent material light over a relatively large length and / or a relatively larger area. Further, the luminescent material may be used to both couple device light out from the light guide as well as generate luminescent material light. Further, the luminescent material may have a relatively high efficiency, desirable peak position and narrow band width (essentially line emission).

[0019] As indicated above, in embodiments the light generating system may comprise a light generating device and a light guide arrangement.

[0020] A light generating device may especially be configured to generate device light. Especially, the light generating device may comprise a light source. The light source may be especially configured to generate light source light. In embodiments, the device light may essentially consist of the light source light. In other embodiments, the device light may essentially consist of converted light source light. In yet other embodiments, the device light2024PF80431

[0021] 5

[0022] may comprise (unconverted) light source light and converted light source light. Light source light may be converted with a luminescent material into luminescent material light and / or with an upconverter into upconverted light (see also below). The term “light generating device” may also refer to a plurality of light generating devices which may provide device light having essentially the same spectral power distributions. In (other) specific embodiments, the term “light generating device” may also refer to a plurality of light generating devices which may provide device light having different spectral power distributions.

[0023] The term “light source” may in principle relate to any light source known in the art. It may be a conventional (tungsten) light bulb, a low pressure mercury lamp, a high pressure mercury lamp, a fluorescent lamp, an LED (light emitting diode). In a specific embodiment, the light source comprises a solid state light source (such as an LED or laser diode (or “diode laser”)). The term “light source” may also relate to a plurality of light sources, such as 2-2000 (solid state) LED light sources. Hence, the term LED may also refer to a plurality of LEDs. Further, the term “light source” may in embodiments also refer to a so-called chip-on-board (COB) light source. The term “COB” especially refers to LED chips in the form of a semiconductor chip that is neither encased nor connected but directly mounted onto a substrate, such as a PCB. Hence, a plurality of light emitting semiconductor light source may be configured on the same substrate. In embodiments, a COB is a multi LED chip configured together as a single lighting module. The term “light source” may also refer to a chip scaled package (CSP). A CSP may comprise a single solid state die with provided thereon a luminescent material comprising layer. The term “light source” may also refer to a midpower package. A midpower package may comprise one or more solid state die(s). The die(s) may be covered by a luminescent material comprising layer. The die dimensions may be equal to or smaller than 2 mm, such as in the range of e.g. 0.2-2 mm. Hence, in embodiments the light source comprises a solid state light source. Further, in specific embodiments, the light source comprises a chip scale packaged LED. Herein, the term “light source” may also especially refer to a small solid state light source, such as having a mini size or micro size. For instance, the light sources may comprise one or more of mini LEDs and micro LEDs. Especially, in embodiment the light sources comprise micro LEDs or “microLEDs” or “pLEDs”. Herein, the term mini size or mini LED especially indicates to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 pm - 1 mm. Herein, the term p size or2024PF80431

[0024] 6

[0025] micro LED especially indicates to solid state light sources having dimensions, such as die dimension, especially length and width, selected from the range of 100 pm and smaller.

[0026] The light source may have a light escape surface. Referring to conventional light sources such as light bulbs or fluorescent lamps, it may be an outer surface of a glass or a quartz envelope. For LED’s it may for instance be the LED die, or when a resin is applied to the LED die, the outer surface of the resin. In principle, it may also be the terminal end of a fiber. The term escape surface especially relates to that part of the light source, where the light actually leaves or escapes from the light source. The light source is configured to provide a beam of light. This beam of light (thus) escapes from the light exit surface of the light source.

[0027] Likewise, a light generating device may comprise a light escape surface, such as an end window. Further, likewise a light generating system may comprise a light escape surface, such as an end window.

[0028] The term “light source” may refer to a semiconductor light-emitting device, such as a light emitting diode (LEDs), a resonant cavity light emitting diode (RCLED), a vertical cavity laser diode (VCSELs), an edge emitting laser, etc... The term “light source” may also refer to an organic light-emitting diode (OLED), such as a passive-matrix (PMOLED) or an active-matrix (AMOLED). In a specific embodiment, the light source comprises a solid-state light source (such as an LED or laser diode). In an embodiment, the light source comprises an LED (light emitting diode). The terms “light source” or “solid state light source” may also refer to a superluminescent diode (SLED).

[0029] The term LED may also refer to a plurality of LEDs. The term “light source” may also relate to a plurality of (essentially identical (or different)) light sources, such as 2-2000 solid state light sources. In embodiments, the light source may comprise one or more micro-optical elements (array of micro lenses) downstream of a single solid-state light source, such as an LED, or downstream of a plurality of solid-state light sources (i.e. e.g. shared by multiple LEDs). In embodiments, the light source may comprise an LED with on-chip optics. In embodiments, the light source comprises pixelated single LEDs (with or without optics) (offering in embodiments on-chip beam steering).

[0030] In embodiments, the light source may be configured to provide primary radiation, which is used as such, such as e.g. a blue light source, like a blue LED, or a green light source, such as a green LED, and a red light source, such as a red LED. Such LEDs, which may not comprise a luminescent material (“phosphor”) may be indicated as direct color LEDs.2024PF80431

[0031] 7

[0032] In other embodiments, however, the light source may be configured to provide primary radiation and part of the primary radiation is converted into secondary radiation. Secondary radiation may be based on conversion by a luminescent material. The secondary radiation may therefore also be indicated as luminescent material radiation. The luminescent material may in embodiments be comprised by the light source, such as an LED with a luminescent material layer or dome comprising luminescent material. Such LEDs may be indicated as phosphor converted LEDs or PC LEDs (phosphor converted LEDs). In other embodiments, the luminescent material may be configured at some distance (“remote”) from the light source, such as an LED with a luminescent material layer not in physical contact with a die of the LED. Hence, in specific embodiments the light source may be a light source that during operation emits at least light at wavelength selected from the range of 380-470 nm. However, other wavelengths may also be possible. This light may partially be converted by the luminescent material.

[0033] In embodiments, the light generating device may comprise a luminescent material. In embodiments, the light generating device may comprise a PC LED. In other embodiments, the light generating device may comprise a direct LED (i.e. no phosphor). In embodiments, the light generating device may comprise a laser device, like a laser diode. In embodiments, the light generating device may comprise a superluminescent diode. Hence, in specific embodiments, the light source may be selected from the group of laser diodes and superluminescent diodes. In other embodiments, the light source may comprise an LED.

[0034] The light source may especially be configured to generate light source light having an optical axis (O), (a beam shape,) and a spectral power distribution. The light source light may in embodiments comprise one or more bands, having band widths as known for lasers.

[0035] The term “light source” may (thus) refer to a light generating element as such, like e.g. a solid state light source, or e.g. to a package of the light generating element, such as a solid state light source, and one or more of a luminescent material comprising element and (other) optics, like a lens, a collimator. A light converter element (“converter element” or “converter”) may comprise a luminescent material comprising element. For instance, a solid state light source as such, like a blue LED, is a light source. A combination of a solid state light source (as light generating element) and a light converter element, such as a blue LED and a light converter element, optically coupled to the solid state light source, may also be a light source (but may also be indicated as light generating device). Hence, a white LED is a light source (but may e.g. also be indicated as (white) light generating device). The term2024PF80431

[0036] 8

[0037] “light source” herein may also refer to a light source comprising a solid state light source, such as an LED or a laser diode or a superluminescent diode or a (stacked) multi -junction light emitting diode. The term “light source” may (thus) in embodiments also refer to a light source that is (also) based on conversion of light, such as a light source in combination with a luminescent converter material. Hence, the term “light source” may also refer to a combination of an LED with a luminescent material configured to convert at least part of the LED radiation, or to a combination of a (diode) laser with a luminescent material configured to convert at least part of the (diode) laser radiation. In embodiments, the term “light source” may also refer to a combination of a light source, like an LED, and an optical filter, which may change the spectral power distribution of the light generated by the light source.

[0038] Especially, the term “light generating device” may be used to address a light source and further (optical components), like an optical filter and / or a beam shaping element, etc.

[0039] The phrases “different light sources” or “a plurality of different light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from at least two different bins. Likewise, the phrases “identical light sources” or “a plurality of same light sources”, and similar phrases, may in embodiments refer to a plurality of solid-state light sources selected from the same bin.

[0040] The term “solid state light source”, or “solid state material light source”, and similar terms, may especially refer to semiconductor light sources, such as a light emitting diode (LED), a laser diode, a superluminescent diode, or multi -junction LED.

[0041] The term “semiconductor light source” may comprise a semiconductor configured to generate light, herein also indicated a “solid state light source”. The term “solid state light source” may refer to a LED, a laser diode, a super luminescent diode, multijunction diode, VCSELs (vertical-cavity surface-emitting laser), etc. The term semiconductor light source and light generating device may herein interchangeably be used; the semiconductor light source or light generating device may comprise one or more semiconductors (configured to generate light) and optionally a luminescent material. Here below, some aspects in relation to (solid state) light sources and light generating devices are described.

[0042] Suitable LEDs may be selected from (III-V compound) semiconductors, such as in specific embodiments semiconductors selected from the group of GaN, AlGaN, InGaN, and AlGalnN, (especially for blue-green), GaP, InP, GalnP, and AlGalnP (especially for red-NIR), GaAs, AlGaAs, InGaAs, and InGaAsP (especially for NIR-MIR). Hence, in2024PF80431

[0043] 9

[0044] embodiments one or more of the light generating devices may comprise a semiconductor selected from the group of GaN, AlGaN, InGaN, AlGalnN, GaP, InP, GalnP, and AlGalnP.

[0045] Especially, the light generating device may be configured to generate device light having a device light centroid wavelength (λdc) selected from the range of 380-780 nm. More especially, the device light centroid wavelength (λdc) may be selected from the range of 380-490 nm. Further, in specific embodiments the device light centroid wavelength (λdc) selected from the range of 400-490 nm. Hence, in embodiments the device light may be violet light or blue light (or comprise a combination of both). Especially, in embodiments the light generating device may comprise a semiconductor-based light generating device.

[0046] The term “centroid wavelength”, also indicated as λc, is known in the art, and refers to the wavelength value where half of the light energy is at shorter and half the energy is at longer wavelengths; the value is stated in nanometers (nm). It is the wavelength that divides the integral of a spectral power distribution into two equal parts as expressed by the formula λc = Σ λ*I(λ) / (Σ I(λ)), where the summation is over the wavelength range of interest, and 1(A) is the spectral energy density (i.e. the integration of the product of the wavelength and the intensity over the emission band normalized to the integrated intensity). The centroid wavelength may e.g. be determined at operation conditions.

[0047] Further, the light generating system may comprise a light guide arrangement. The light guide arrangement may comprise a light guide or waveguide, which may especially be elongated. For instance, the light guide may comprise an optical fiber (transmissive for device light) or a light guide plate (transmissive for device light).

[0048] As the light guide may be elongated, the light guide may have a length larger than at least one cross-sectional dimension perpendicular to the length. Such cross-sectional dimensions may be selected from a width, a height, a diameter, a short axis of an ellipse, a long axis of an ellipse, etc. For the sake of clarity, the other dimension, perpendicular to the length (axis) may be defined as circular equivalent diameter of a cross-sectional area defined perpendicular to the length (axis). The equivalent circular diameter (or ECD) (or “circular equivalent diameter”) of an (irregularly shaped) two-dimensional shape is the diameter of a circle of equivalent area. For instance, the equivalent circular diameter of a square with side a is 2*a*SQRT(1 / π). For a circle, the diameter is the same as the equivalent circular diameter. Would a circle in an xy-plane with a diameter D be distorted to any other shape (in the xy-plane), without changing the area size, than the equivalent circular diameter of that shape would be D. Herein, the length (axis) may also be indicated as first dimension.2024PF80431

[0049] 10

[0050] Hence, the first dimension (DI) may be a length, and the second dimension (D2) may be a circular equivalent diameter of a cross-sectional area defined perpendicular to the first dimension (DI). Especially, in embodiments D2 / D1≤0.75, more especially D2 / D1≤0.5. In specific embodiments, D2 / D1≤0.1. For instance, in embodiments D2 / D1≥0.0001, like in specific embodiments 0.0001≤D2 / D1≤0.5, though other values may also be possible.

[0051] Further, the light guide arrangement may comprise a light in-coupling area, a first dimension (DI), a second dimension (D2), and a light out-coupling area over at least part of the first dimension (DI). Assuming a fiber-like light guide, an end face may comprise the light in-coupling area, whereas a circumferential face (which may in embodiments be essentially perpendicular to the end face) of the fiber-like light guide may comprise the light out-coupling area. Assuming a plate-like light guide, a side face may comprise the light incoupling area, whereas a top-face and / or a bottom-face (which may in embodiments be essentially perpendicular to the side face) of the plate-like light guide may comprise the light out-coupling area.

[0052] Especially, the light in-coupling area may be configured in a light receiving relationship with the light generating device. Hence, the light generating device may be configured upstream of the light in-coupling area. The terms “upstream” and “downstream” relate to an arrangement of items or features relative to the propagation of the light from a light generating means (here the especially the light source), wherein relative to a first position within a beam of light from the light generating means, a second position in the beam of light closer to the light generating means is “upstream”, and a third position within the beam of light further away from the light generating means is “downstream”.

[0053] Further, in embodiments, along at least part of the first dimension (DI) of the light guide arrangement downstream of the light in-coupling area, the light guide arrangement is at least partly transmissive for the device light coupled into the light guide arrangement via the light in-coupling area.

[0054] Hence, the light guide arrangement may comprise a body comprising light transmissive material. Especially, the body may have as dimensions the first dimension and the second dimension. Hence, in embodiments the body may be an optical fiber or a light guide plate.

[0055] Especially, the light transmissive material has a light transmission in the range of 50-100 %, especially in the range of 70-100%, for light having a wavelength selected from2024PF80431

[0056] 11

[0057] the visible wavelength range. Herein, the term “visible light” especially relates to light having a wavelength selected from the range of 380-780 nm.

[0058] The transmission (or light permeability) can be determined by providing light at a specific wavelength with a first intensity to the light transmissive material under perpendicular radiation and relating the intensity of the light at that wavelength measured after transmission through the material, to the first intensity of the light provided at that specific wavelength to the material (see also E-208 and E-406 of the CRC Handbook of Chemistry and Physics, 69th edition, 1988-1989).

[0059] In specific embodiments, a material may be considered transmissive when the transmission of the radiation at a wavelength or in a wavelength range, especially at a wavelength or in a wavelength range of radiation generated by a source of radiation as herein described, through a 1 mm thick layer of the material, especially even through a 5 mm thick layer of the material, under perpendicular irradiation with said radiation is at least about 20%, such as at least 40%, like at least 60%, such as especially at least 80%, such as at least about 85%, such as even at least about 90%.

[0060] The light transmissive material has light guiding or wave guiding properties. Hence, the light transmissive material is herein also indicated as waveguide material or light guide material. The light transmissive material will in general have (some) transmission of one or more of (N)UV, visible, and (N)IR radiation, such as in embodiments at least visible light, in a direction perpendicular to the length of the light transmissive material. Without the activator (dopant) such as trivalent cerium, the internal transmission in the visible might be close to 100%.

[0061] The transmission of the light transmissive material (as such) for one or more luminescence wavelengths and / or one or more device light wavelengths may be at least 80% / cm, such as at least 90% / cm, even more especially at least 95% / cm, such as at least 98% / cm, such as at least 99% / cm. This implies that e.g. a 1 cm3cubic shaped piece of light transmissive material, under perpendicular irradiation of radiation having a selected luminescence wavelength (such as a wavelength corresponding to an emission maximum of the luminescence of the luminescent material of the light transmissive material) and / or one or more device light wavelengths, will have a transmission of at least 95%.

[0062] Herein, values for transmission especially refer to transmission without taking into account Fresnel losses at interfaces (with e.g. air). Hence, the term “transmission” especially refers to the internal transmission. The internal transmission may e.g. be determined by measuring the transmission of two or more bodies having a different width2024PF80431

[0063] 12

[0064] over which the transmission is measured. Then, based on such measurements the contribution of Fresnel reflection losses and (consequently) the internal transmission can be determined. Hence, especially, the values for transmission indicated herein, disregard Fresnel losses.

[0065] In embodiments, an anti-reflection coating may be applied to the luminescent body, such as to suppress Fresnel reflection losses (during the light in-coupling process).

[0066] In addition to a high transmission for the wavelength(s) of interest, also the scattering for the wavelength(s) may especially be low. Hence, the mean free path for the wavelength of interest only taking into account scattering effects (thus not taking into account possible absorption (which should be low anyhow in view of the high transmission), may be at least 0.5 times the length of the body, such as at least the length of the body, like at least twice the length of the body. For instance, in embodiments the mean free path only taking into account scattering effects may be at least 5 mm, such as at least 10 mm. The wavelength of interest may especially be the wavelength at maximum emission of the luminescence of the luminescent material. The term “mean free path” is especially the average distance a ray will travel before experiencing a scattering event that will change its propagation direction.

[0067] In embodiments, the element comprising the light transmissive material may essentially consist of the light transmissive material. In specific embodiments, the element comprising the light transmissive material may be a light transparent element.

[0068] Especially, the light transmissive element, such as the light transparent element, may in embodiments have an absorption length and / or a scatter length of at least the length (or thickness) of the light transmissive element, such as at least twice the length of the light transmissive element. The absorption length may be defined as the length over which the intensity of the light along a propagation direction due to absorption drops with 1 / e. Likewise, the scatter length may be defined as the length along a propagation direction along which light is lost due to scattering and drops thereby with a factor 1 / e. Here, the length may thus especially refer to the distance between a primary face and a secondary face of the light transmissive element, with the light transmissive material configured between the primary face and the secondary face.

[0069] The light transmissive material may comprise one or more materials selected from the group consisting of a transmissive organic material, such as selected from the group consisting of PE (polyethylene), PP (polypropylene), PEN (polyethylene napthalate), PC (polycarbonate), polyurethanes (PU), polymethylacrylate (PMA), polymethylmethacrylate (PMMA) (Plexiglas or Perspex), polymethacrylimide (PMI), polymethylmethacrylimide2024PF80431

[0070] 13

[0071] (PMMI), styrene acrylonitrile resin (SAN), cellulose acetate butyrate (CAB), silicone, polyvinylchloride (PVC), polyethylene terephthalate (PET), including in an embodiment (PETG) (glycol modified polyethylene terephthalate), PDMS (polydimethylsiloxane), and COC (cyclo olefin copolymer). Especially, the light transmissive material may comprise an aromatic polyester, or a copolymer thereof, such as e.g. one or more of polycarbonate (PC), poly (methyl)methacrylate (P(M)MA), polyglycolide or polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyethylene adipate (PEA), polyhydroxy alkanoate (PHA), polyhydroxy butyrate (PHB), poly(3-hydroxybutyrate-co-3 -hydroxy valerate) (PHBV), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN). Especially, the light transmissive material may comprise polyethylene terephthalate (PET). Hence, the light transmissive material is especially a polymeric light transmissive material.

[0072] However, in another embodiment the light transmissive material may comprise an inorganic material. Especially, the inorganic light transmissive material may be selected from the group consisting of glasses, (fused) quartz, transmissive ceramic materials, and silicones. Also hybrid materials, comprising both inorganic and organic parts may be applied. Especially, the light transmissive material comprises one or more of PMMA, transparent PC, or glass.

[0073] For instance, the light transmissive material may comprise a ceramic body, like a garnet type of material. In alterative embodiments, the light transmissive material may comprise an alumina material, such as an Al2O3based material. In embodiments, the light transmissive material may comprise e.g. sapphire. Other materials may also be possible like one or more of CaF2, MgO, BaF2, A3B5O12 garnet, ALON (aluminum oxynitride), MgAl2O4and MgF2.

[0074] Hence, light transmissive material mentioned herein may, as such, be transparent for the device light. A body or layer comprising a light transmissive material may in embodiments consist of light transmissive material, and be (essentially) transparent, or may in other embodiments comprise light transmissive material and another material, like the particulate material. In these latter embodiments, the body or layer may still be transmissive for device light, or even essentially transparent for device light, e.g. dependent upon a concentration of the particulate material. Hence, in embodiments the light transmissive materials mentioned herein are transparent for device light.2024PF80431

[0075] 14

[0076] A light transmissive material wherein (particulate) luminescent material is embedded, may also be indicated as a light transmissive host material, or a light transmissive matrix material.

[0077] When the device light is coupled into the light guide, via total internal reflection the device light may propagate through the light guide. Hence, via multiple internal reflections, the device light may propagate through the light guide. While propagating, part of the device light may be coupled out or converted into luminescent material light (which may at least partly be coupled out).

[0078] Hence, in embodiments the light generating system may be configured such that during operation of the light generating device at least part of the device light propagates through the light guide arrangement over at least part of the first dimension (DI) while being totally internally reflected multiple times and subsequently coupled out from the light guide arrangement and emanating from the light out-coupling area of the light guide arrangement over at least part of the first dimension (DI).

[0079] In this way, a light emitting light guide arrangement may be provided, of which the light emanating from the light guide arrangement may comprise luminescent material light and optionally unconverted device light. To this end, the light guide arrangement may comprise a luminescent material. The term “luminescent material” especially refers to a material that can convert first radiation, especially one or more of UV radiation and blue radiation, into second radiation. In general, the first radiation and second radiation have different spectral power distributions. Hence, instead of the term “luminescent material”, also the terms “luminescent converter” or “converter” or “luminescent converter material” may be applied. In general, the second radiation has a spectral power distribution at larger wavelengths than the first radiation, which is the case in the so-called downconversion. In specific embodiments, however the second radiation has a spectral power distribution with intensity at smaller wavelengths than the first radiation, which is the case in the so-called up-conversion.

[0080] In embodiments, the “luminescent material” may especially refer to a material that can convert radiation into e.g. visible and / or infrared light. For instance, in embodiments the luminescent material may be able to convert one or more of UV radiation and blue radiation, into visible light. The luminescent material may in specific embodiments also convert radiation into infrared radiation (IR). Hence, upon excitation with radiation, the luminescent material emits radiation. In general, the luminescent material will be a down converter, i.e. radiation of a smaller wavelength is converted into radiation with a larger2024PF80431

[0081] 15

[0082] wavelength (λex<λem), though in specific embodiments the luminescent material may comprise up-converter luminescent material, i.e. radiation of a larger wavelength is converted into radiation with a smaller wavelength (λex>λem).

[0083] In embodiments, the term “luminescence” may refer to phosphorescence. In embodiments, the term “luminescence” may also refer to fluorescence. Instead of the term “luminescence”, also the term “emission” may be applied. Hence, the terms “first radiation” and “second radiation” may refer to excitation radiation and emission (radiation), respectively. Likewise, the term “luminescent material” may in embodiments refer to phosphorescence and / or fluorescence.

[0084] The term “luminescent material” may also refer to a plurality of different luminescent materials. Examples of possible luminescent materials are indicated below. Hence, the term “luminescent material” may in specific embodiments also refer to a luminescent material composition. Instead of the term “luminescent material” also the term “phosphor” may be applied. These terms are known to the person skilled in the art.

[0085] In embodiments, luminescent materials are selected from garnets and nitrides, especially doped with trivalent cerium or divalent europium, respectively. The term “nitride” may also refer to oxynitride or nitridosilicate, etc. Alternatively or additionally, the luminescent material(s) may be selected from silicates, especially doped with divalent europium.

[0086] In specific embodiments the luminescent material comprises a luminescent material of the type A3B5O12:Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, especially (at least) one or more of Y, Gd, Tb and Lu, and wherein B in embodiments comprises one or more of Al, Ga, In and Sc. Especially, A may comprise one or more of Y, Gd and Lu, such as especially one or more of Y and Lu. Especially, B may comprise one or more of Al and Ga, more especially at least Al, such as essentially entirely Al. Hence, especially suitable luminescent materials are cerium comprising garnet materials. Embodiments of garnets especially include A3B5O12garnets, wherein A comprises at least yttrium or lutetium and wherein B comprises at least aluminum. Such garnets may be doped with cerium (Ce), with praseodymium (Pr) or a combination of cerium and praseodymium; especially however with Ce. Especially, B may comprise aluminum (Al); however, in addition to aluminum, B may also partly comprise gallium (Ga) and / or scandium (Sc) and / or indium (In), especially up to about 20% of B, more especially up to about 10 % of B (i.e. the B ions essentially consist of 90 or more mole % of Al and 10 or less mole % of one or more of Ga, Sc and In); B may especially comprise up to about 10% gallium. In another variant, B2024PF80431

[0087] 16

[0088] and O may at least partly be replaced by Si and N. The element A may especially be selected from the group consisting of yttrium (Y), gadolinium (Gd), terbium (Tb) and lutetium (Lu). Further, Gd and / or Tb are especially only present up to an amount of about 20% of A. In a specific embodiment, the garnet luminescent material comprises (Y1-xLux)3B5O12:Ce, wherein x is equal to or larger than 0 and equal to or smaller than 1. The term “: Ce”, indicates that part of the metal ions (i.e. in the garnets: part of the “A” ions) in the luminescent material is replaced by Ce. For instance, in the case of (Y1-xLux)3Al5O12:Ce, part of Y and / or Lu is replaced by Ce. This is known to the person skilled in the art. Ce will replace A in general for not more than 10%; in general, the Ce concentration will be in the range of 0.1 to 4%, especially 0.1 to 2% (relative to A). Assuming 1% Ce and 10% Y, the full correct formula could be (Y0.1Lu0.89Ce0.01)3Al5O12. Ce in garnets is substantially or only in the trivalent state, as is known to the person skilled in the art.

[0089] In embodiments, the luminescent material (thus) comprises A3B5O12wherein in specific embodiments at maximum 10% of B-0 may be replaced by Si-N.

[0090] In specific embodiments the luminescent material comprises (YxiA’X2CeX3)3(AlyiB’y2)5Oi2, wherein xl+x2+x3=l, wherein x3>0, wherein 0<x2+x3<0.2, wherein yl+y2=l, wherein especially 0<y2<0.2, wherein A’ comprises one or more elements selected from the group consisting of lanthanides, and wherein B’ comprises one or more elements selected from the group consisting of Ga, In and Sc. In embodiments, x3 is selected from the range of 0.001-0.1. In the present invention, especially xl>0, such as >0.2, like at least 0.8. Garnets with Y may provide suitable spectral power distributions.

[0091] In specific embodiments at maximum 10% of B-0 may be replaced by Si-N. Here, B in B-0 refers to one or more of Al, Ga, In and Sc (and O refers to oxygen); in specific embodiments B-0 may refer to Al-O. As indicated above, in specific embodiments x3 may be selected from the range of 0.001-0.04. Especially, such luminescent materials may have a suitable spectral distribution (see however below), have a relatively high efficiency, have a relatively high thermal stability, and allow a high CRI (optionally in combination with (the) light of other sources of light as described herein). Hence, in specific embodiments A may be selected from the group consisting of Lu and Gd. Alternatively or additionally, B may comprise Ga. Hence, in embodiments the luminescent material comprises (Yxi(Lu, Gd)X2CeX3)3(AlyiGay2)5Oi2, wherein Lu and / or Gd may be available. Even more especially, x3 is selected from the range of 0.001-0.1, wherein 0<x2+x3<0.1, and wherein 0<y2<0.1. Further, in specific embodiments, at maximum 1% of B-0 may be replaced by Si-N. Here, the percentage refers to moles (as known in the art); see e.g. also EP3149108. In yet2024PF80431

[0092] 17

[0093] further specific embodiments, the luminescent material comprises (YxiCexs^ALOn, wherein xl+x3=l, and wherein 0<x3<0.2, such as 0.001-0.1.

[0094] In specific embodiments, the light generating device may (only) include luminescent materials selected from the type of cerium comprising garnets. In even further specific embodiments, the light generating device includes a single type of luminescent materials, such as (YxiA’x2Cex3)3(AlyiB’y2)5Oi2. Hence, in specific embodiments the light generating device comprises luminescent material, wherein at least 85 weight%, even more especially at least about 90 wt.%, such as yet even more especially at least about 95 weight % of the luminescent material comprises (YxiA’x2Cex3)3(AlyiB’y2)5Oi2. Here, wherein A’ comprises one or more elements selected from the group consisting of lanthanides, and wherein B’ comprises one or more elements selected from the group consisting of Ga, In and Sc, wherein xl+x2+x3=l, wherein x3>0, wherein 0<x2+x3<0.2, wherein yl+y2=l, wherein 0<y2<0.2. Especially, x3 is selected from the range of 0.001-0.1. Note that in embodiments x2=0. Alternatively or additionally, in embodiments y2=0.

[0095] In specific embodiments, A may especially comprise at least Y, and B may especially comprise at least Al.

[0096] Alternatively or additionally, the luminescent material may comprise a luminescent material of the type A3Si6N11:Ce3+, wherein A comprises one or more of Y, La, Gd, Tb and Lu, such as in embodiments one or more of La and Y.

[0097] In embodiments, the luminescent material may alternatively or additionally comprise one or more of MS:Eu2+and / or M2Si5N8:Eu2+and / or MAlSiN3:Eu2+and / or Ca2AlSi3O2N5:Eu2+, etc., wherein M comprises one or more of Ba, Sr and Ca, especially in embodiments at least Sr. Hence, in embodiments, the luminescent may comprise one or more materials selected from the group consisting of (Ba, Sr, Ca)S: Eu, (Ba, Sr, Ca)AlSiN3: Eu and (Ba, Sr, Ca)2SisN8: Eu. In these compounds, europium (Eu) is substantially or only divalent, and replaces one or more of the indicated divalent cations. In general, Eu will not be present in amounts larger than 10% of the cation; its presence will especially be in the range of about 0.5 to 10%, more especially in the range of about 0.5 to 5% relative to the cation(s) it replaces. The term “: Eu”, indicates that part of the metal ions is replaced by Eu (in these examples by Eu2+). For instance, assuming 2% Eu in CaAlSi Eu, the correct formula could be (Cao.98Euo.o2)AlSiN3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba. The material (Ba, Sr, Ca)S: Eu can also be indicated as MS: Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M2024PF80431

[0098] 18

[0099] comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). Further, the material (Ba, Sr, Ca)2SisN8: Eu can also be indicated as M2Si5N8:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound Sr and / or Ba. In a further specific embodiment, M consists of Sr and / or Ba (not taking into account the presence of Eu), especially 50 to 100%, more especially 50 to 90% Ba and 50 to 0%, especially 50 to 10% Sr, such as Ba1.5Sr0.5Si5N8:Eu (i.e. 75 % Ba; 25% Sr). Here, Eu is introduced and replaces at least part of M, i.e. one or more of Ba, Sr, and Ca). Likewise, the material (Ba, Sr, Ca)AlSiN3: Eu can also be indicated as MAlSiN3:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca). Eu in the above indicated luminescent materials is substantially or only in the divalent state, as is known to the person skilled in the art.

[0100] In embodiments, a red luminescent material may comprise one or more materials selected from the group consisting of (Ba, Sr, Ca)S: Eu, (Ba, Sr, Ca)AlSiN3: Eu and (Ba, Sr, Ca)2SisN8: Eu. In these compounds, europium (Eu) is substantially or only divalent, and replaces one or more of the indicated divalent cations. In general, Eu will not be present in amounts larger than 10% of the cation; its presence will especially be in the range of about 0.5 to 10%, more especially in the range of about 0.5 to 5% relative to the cation(s) it replaces. The term “: Eu”, indicates that part of the metal ions is replaced by Eu (in these examples by Eu2+). For instance, assuming 2% Eu in CaAlSi Eu, the correct formula could be (Cao.98Euo.o2)AlSiN3. Divalent europium will in general replace divalent cations, such as the above divalent alkaline earth cations, especially Ca, Sr or Ba.

[0101] The material (Ba, Sr, Ca)S: Eu can also be indicated as MS: Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca).

[0102] Further, the material (Ba, Sr, Ca)2SisN8: Eu can also be indicated as M2Si5N8:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound Sr and / or Ba. In a further specific embodiment, M consists of Sr and / or Ba (not taking into2024PF80431

[0103] 19

[0104] account the presence of Eu), especially 50 to 100%, more especially 50 to 90% Ba and 50 to 0%, especially 50 to 10% Sr, such as Ba1.5Sr0.5Si5N8:Eu (i.e. 75 % Ba; 25% Sr). Here, Eu is introduced and replaces at least part of M, i.e. one or more of Ba, Sr, and Ca).

[0105] Likewise, the material (Ba, Sr, Ca)AlSiN3: Eu can also be indicated as MAlSiN3:Eu, wherein M is one or more elements selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca); especially, M comprises in this compound calcium or strontium, or calcium and strontium, more especially calcium. Here, Eu is introduced and replaces at least part of M (i.e. one or more of Ba, Sr, and Ca).

[0106] In embodiments, the luminescent material may comprise a luminescent material of the type M1-xLi3-2yAl1+2y-zSizO4-4y-zN4y+z:Eux. Herein, M may comprise one or more of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), such as especially one or more of Ca, Sr, and Ba. Hence, M1-xLi3-2yAl1+2y-zSizO4-4y-zN4y+z:Euxmay especially refer to (Mg, Ca, Sr, Ba)i-xLi3-2yAli+2y-zSizO4-4y-zN4y+z: Eux. Such a luminescent material may be indicated as an SLA-type phosphor, or SLA phosphor. Luminescent materials of the type Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z: Eux may be described in US2021171827A1, which is hereby herein incorporated by reference. In Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z: Eux, x may be selected from the range of 0 < x < 0.1, such as from the range of 0.0005 < x < 0.08, especially from the range of 0.001 < x < 0.05. Hence, europium (Eu) may not replace more than 10% of the cation M, and may substantially or only be in the divalent state (Eu2+), as is known to the person skilled in the art. Further, in Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z: Eux, y may be selected from the range of 0 < y < 1, such as from the range of 0 < y < 0.75, especially from the range of 0 < y < 0.6. In specific embodiments, y = 0. In Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z: Eux, z may be selected from the range of 0 < z < 0.1, such as from the range of 0 < z < 0.07, especially from the range of 0 < z < 0.05. Hence, in embodiments, in an SLA phosphor, SiN may replace A1O to a maximum of 10 mole%. In embodiments, an SLA phosphor may crystallize in a UCr4C4 type crystal structure. Hence, the luminescent material may comprise a luminescent material of the type Mi-xLi3-2yAli+2y-zSizO4-4y-zN4y+z: Eux, wherein M comprises one or more of Ca, Sr, and Ba, wherein 0 < x < 0.04, wherein 0 < y < 1, wherein 0 < z < 0.05, and wherein y + z < 1. In embodiments, part of the Al in the SLA phosphor may be replaced by gallium (Ga). Hence, the luminescent material may comprise a luminescent material of the type Mi-xLi3-2y(Ali-bGab)i+2y-zSizO4-4y-zN4y+z: Eux, wherein M may comprise one or more of Mg, Ca, Sr, and Ba, and x, y, and z may be as indicated above. Such a luminescent material may be indicated as an SLGA phosphor, especially in embodiments wherein b > 0. In embodiments, b in the formula Mi-xLi3-2y(Ali-2024PF80431

[0107] 20

[0108] bGab)i+2y-zSizO4-4y-zN4y+z: Eux may be selected from the range of > 0, such as from the range of > 0.05, especially from the range of > 0.1, like from the range of > 0.15. Additionally or alternatively, b may be selected from the range of < 0.6, such as from the range of < 0.5, especially from the range of < 0.4, like from the range of < 0.3. Especially, 0 < b < 0.6 may apply, such as 0.05 < b < 0.5, especially 0.1 < b < 0.3, like 0.15 < b < 0.3.

[0109] Further, the luminescent material may comprise a SiAlON phosphor, such as selected from the group comprising (a) Si12-m-nAlm+nOnN16-n:Eu2+(α-SiAlON), (b) Si6-nAlnOnN8-n:Eu2+, wherein 0 < n < 4.2 (P-SiAlON), and (c) Si2-nAlnO1+nN2-n:Eu2+, wherein 0 < n < 0.2 (O-SiAlON).

[0110] Eu in the above indicated luminescent materials is substantially or only in the divalent state, as is known to the person skilled in the art.

[0111] Blue luminescent materials may comprise YSO (Y2SiO5:Ce3+), or similar compounds, or BAM (BaMgAl10O17:Eu2+), or similar compounds.

[0112] The term “luminescent material” herein especially relates to inorganic luminescent materials.

[0113] Hence, when M (or A) in chemical formulas refer to n different elements, this may imply that the relevant formula may comprise for the M (or A) position in the formula essentially any permutation of the n different elements. For instance, when M=Ba, Sr, Ca or when M comprises one or more of Ba, Sr, Ca or when M refers to Ba, Sr, Ca, i.e. n=3, this may imply that in the formula Ba, Sr, Ca, (BaxSry), (BaxCay), (CaxSry), or (BaxSryCaz), may be available, wherein in general x+y+z=l.

[0114] Referring to e.g. M’xM2-2XAXe, (see also below) this may refer to e.g. one or more of K2SiF6:Mn4+and of Rb2SiF6:Mn4+, or (KxRby)2SiF6:Mn4+, etc. Referring to (Ba, Sr, Ca)AlSiN3: Eu, this may imply BaAlSiN3: Eu, SrAlSiN3: Eu, CaAlSiN3: Eu, (BaxSry)AlSiN3: Eu, (BaxCay)AlSiN3: Eu, (CaxSry)AlSiN3: Eu, or (BaxSryCaz)AlSiN3: Eu.

[0115] Referring to e.g. A3BsOi2: Ce, wherein A in embodiments comprises one or more of Y, La, Gd, Tb and Lu, this may imply Y3BsOi2: Ce, La3BsOi2: Ce, Gd3B5O12:Ce, Tb3B5O12:Ce, Lu3BsOi2: Ce, but also e.g. (Yx, Gdy)3B50i2: Ce, (Yx, Luy)3B50i2: Ce, (Gdx, Luy)3B50i2: Ce, (Yx, Gdy, Luz)3B50i2: Ce, etc. etc., with hereby only limiting for the sake of economy to unary, binary, and ternary examples, though quaternary and higher examples are not excluded herein. Further, indications like “K, Rb” or Ba, Sr, Ca, and similar indications (see also above), may indicate one or more of such elements. Hence, (K,Rb)₂SiF₆:Mn⁴⁺, may e.g. refer to K2SiFe: Mn4+and of Rb2SiF6:Mn4+, or (KxRby)2SiF6:Mn4+. Also herein in general x+y=l. Likewise, K2(Si,Ti)F6:Mn4+, may e.g. refer to K2SiFe: Mn4+, K2TiFe: Mn4+, or2024PF80431

[0116] 21

[0117] K₂(Siₐ,Tiᵦ)F₆:Mn⁴⁺. Also herein in general a+b=l. Hence, when M (or A), etc. may refer to n different elements, with n being at least two, 2n-l permutations may in principle be possible.

[0118] Alternatively or additionally, also other luminescent materials may be applied. For instance quantum dots (or other quantum confinement structures) and / or organic dyes may be applied and may optionally be embedded in transmissive matrices like e.g. polymers, like PMMA, or polysiloxanes, etc. etc.

[0119] Quantum dots are small crystals of semiconducting material generally having a width or diameter of only a few nanometers. When excited by incident light, a quantum dot emits light of a color determined by the size and material of the crystal. Light of a particular color can therefore be produced by adapting the size of the dots. Most known quantum dots with emission in the visible range are based on cadmium selenide (CdSe) with a shell such as cadmium sulfide (CdS) and zinc sulfide (ZnS). Cadmium free quantum dots such as indium phosphide (InP), and copper indium sulfide (CuInS₂) and / or silver indium sulfide (AgInS₂) can also be used. Quantum dots show very narrow emission band and thus they show saturated colors. Furthermore the emission color can easily be tuned by adapting the size of the quantum dots. Any type of quantum dot known in the art may be used in the present invention. However, it may be preferred for reasons of environmental safety and concern to use cadmium-free quantum dots or at least quantum dots having a very low cadmium content.

[0120] Instead of quantum dots or in addition to quantum dots, also other quantum confinement structures may be used. The term “quantum confinement structures” should, in the context of the present application, be understood as e.g. quantum wells, quantum dots, quantum rods, tripods, tetrapods, or nanowires, etcetera.

[0121] Organic phosphors can be used as well. Examples of suitable organic phosphor materials are organic luminescent materials based on perylene derivatives, for example compounds sold under the name Lumogen® by BASF. Examples of suitable compounds include, but are not limited to, Lumogen® Red F305, Lumogen® Orange F240, Lumogen® Yellow F083, and Lumogen® F170.

[0122] Different luminescent materials may have different spectral power distributions of the respective luminescent material light. Alternatively or additionally, such different luminescent materials may especially have different color points (or dominant wavelengths).

[0123] As indicated above, other luminescent materials may also be possible. Hence, in specific embodiments the luminescent material is selected from the group of divalent europium containing nitrides, divalent europium containing oxynitrides, divalent europium2024PF80431

[0124] 22

[0125] containing silicates, cerium comprising garnets, and quantum structures. Quantum structures may e.g. comprise quantum dots or quantum rods (or other quantum type particles) (see above). Quantum structures may also comprise quantum wells. Quantum structures may also comprise photonic crystals.

[0126] As can be derived from the above, the term “different luminescent materials” may refer to luminescent materials that are different, or to two compositions, each including at least one luminescent material in common, but wherein the compositions differ. For instance, a first luminescent material comprising luminescent materials A and B, and a second luminescent material comprising only A or only B, or comprising both A and B, but in a different weight ratio. Such first luminescent material and second luminescent material may have different spectral power distributions of their respective luminescent material light.

[0127] In embodiments, the luminescent material may comprise a luminescent material of the type M’xM2-2xAX6 doped with tetravalent manganese, wherein M’ comprises an alkaline earth cation, M comprises a cation, like in embodiments an alkaline cation, and x is in the range of 0-1, wherein A comprises a tetravalent cation, for instance comprising one or more of silicon, germanium, and titanium, wherein X comprises a monovalent anion, in embodiments at least comprising fluorine. A luminescent material of the type M’xM2-2xAX6 doped with tetravalent manganese is amongst others described in WO2013121355A1, which is herein incorporated by reference. Passages from WO2013121355A1 are also copied herein.

[0128] Herein, M’xM2-2xAX6 doped with tetravalent manganese, may further also shortly be indicated as “phosphor”, i.e. the phrase " phosphor comprising M’xM2-2xAX6 doped with tetravalent manganese" may in an embodiment also be read as M’xM2-2xAX6 doped with tetravalent manganese phosphor, or (tetravalent) Mn-doped M’xM2-2xAX6 phosphor, or shortly "phosphor".

[0129] Relevant alkaline cations (M) are sodium (Na), potassium (K) and rubidium (Rb). Optionally, also lithium and / or cesium may be applied. In a preferred embodiment, M comprises at least potassium. In yet another embodiment, M comprises at least rubidium. The phrase “wherein M comprises at least potassium” indicates for instance that of all M cations in a mole M’xM2-2xAX6, a fraction comprises K+and an optionally remaining fraction comprises one or more other monovalent (alkaline) cations (see also below). In another preferred embodiment, M comprises at least potassium and rubidium. Optionally, the M’XM2-2xAXe luminescent material has the hexagonal phase. In yet another embodiment, the M’XM2-2xAXe luminescent material has the cubic phase. Note that also NH4 may be applied.2024PF80431

[0130] 23

[0131] Relevant alkaline earth cations (M’) are magnesium (Mg), strontium (Sr), calcium (Ca) and barium (Ba), especially one or more of Sr and Ba.

[0132] In an embodiment, a combination of different alkaline cations may be applied. In yet another embodiment, a combination of different alkaline earth cations may be applied. In yet another embodiment, a combination of one or more alkaline cations and one or more alkaline earth cations may be applied. For instance, KRb0.5Sr0.25AX6 might be applied. As indicated above, x may be in the range of 0-1, especially x<l. In an embodiment, x=0.

[0133] The term “tetravalent manganese” refers to Mn4+. This is a well-known luminescent ion. In the formula as indicated above, part of the tetravalent cation A (such as Si) is being replaced by manganese. Hence, M’xM2-2xAX6 doped with tetravalent manganese may also be indicated as M’xM2-2xAi-mMnmX6. The mole percentage of manganese, i.e. the percentage it replaces the tetravalent cation A will in general be in the range of 0.1-15 %, especially 1-12 %, i.e. m is in the range of 0.001-0.15, especially in the range of 0.01-0.12, though other values may also be possible.

[0134] A comprises a tetravalent cation, and preferably at least comprises silicon. A may optionally (further) comprise one or more of titanium (Ti), germanium (Ge), stannum (Sn) and zinc (Zn). Preferably, at least 80%, even more preferably at least 90%, such as at least 95% of M consists of silicon. Hence, in a specific embodiment, M’xM2-2xAX6may also be described as M’xM2-2xAi-m-t-g-s-zrMnmTitGegSnsZrzrX6, wherein m and x are as indicated above, and wherein t,g,s,zr are each individually preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05, wherein t+g+s+zr is smaller than 1, especially equal to or smaller than 0.2, preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05, and wherein A is especially Si. X is preferably fluorine (F).

[0135] As indicated above, M relates to monovalent cations, but preferably at least comprises potassium and / or rubidium. Other monovalent cations that may further be comprised by M can be selected from the group consisting of lithium (Li), sodium (Na), cesium (Cs) and ammonium (NH4). In an embodiment, preferably at least 80%(i.e. 80% of all moles of the type M), even more preferably at least 90%, such as 95% of M consists of potassium and / or rubidium. Especially, in these embodiments x is thus zero.

[0136] Hence, in a specific embodiment, M’xM2-2xAX6 can also be described as (K1-r-l-n-c-nhRbrLilNanCsc(NH4)nh)2AX6, wherein r is in the range of 0-1, wherein l,n,c,nh are each individually preferably in the range of 0-1, preferably 0-0.2, especially 0-0.1, even more especially 0-0.05, and wherein r+ 1+n+c+nh is in the range of 0-1, especially 1+n+c+nh is2024PF80431

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[0138] smaller than 1, especially equal to or smaller than 0.2, preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05. X is preferably fluorine (F).

[0139] As indicated above, instead of or in addition to the alkaline cation(s), also one or more alkaline earth cations may be present. Hence, in a specific embodiment, M’XM2-2XAXe can also be described as MgmgCaCaSrsrBaba(KkRbrLiiNanCsc(NH4)nh)2AX6, with k, r, 1, n, c, nh each individually being in the range of 0-1, wherein mg, ca, sr, ba are each individually in the range of 0-1, and wherein mg+ca+sr+ba+k+ r+ l+n+c+nh=l. In embodiments, k=l, and the others (mg, ca, sr, ba, r, 1, n, c, nh) are zero.

[0140] As indicated above, X relates to a monovalent anion, but at least comprises fluorine. Other monovalent anions that may optionally be present may be selected from the group consisting of chlorine (Cl), bromine (Br), and iodine (I). Preferably, at least 80%, even more preferably at least 90%, such as 95% of X consists of fluorine. Hence, in a specific embodiment, M’xM2-2xAX6 can also be described as M’xM2-2XA(Fi.ci-b-iClciBrbIi)6, wherein cl,b,i are each individually preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05, and wherein cl+b+i is smaller than 1, especially equal to or smaller than 0.2, preferably in the range of 0-0.2, especially 0-0.1, even more especially 0-0.05.

[0141] Especially, X essentially consists of F (fluorine).

[0142] Hence, M’xM2-2XAX6 can also be described as (Ki-r-i-n-c-nh RbrLiiNanCsc(NH4)nh)2Sii-m-t-g-s-zrMnmTitGegSnsZrzr(Fi-ci-b-iClciBrbIi)6, with the values for r,l,n,c,nh,m,t,g,s,zr,cl,b,i as indicated above. X is preferably fluorine (F).

[0143] Even more especially, M’xM2-2XAX6 can also be described as MgmgCacaSrsrBaba(KkRbrLilNanCsc(NH4)nh)2Sil.m-t-g-s-zrMnmTitGegSnsZrzr(F l-cl-b-iClclBrbIi)6, with k, r, 1, n, c, nh each individually being in the range of 0-1, wherein mg, ca, sr, ba are each individually in the range of 0-1, wherein mg+ca+sr+ba+k+ r+ l+n+c+nh=l, and with the values for m,t,g,s,zr,cl,b,i as indicated above. X is preferably fluorine (F).

[0144] In an embodiment, M’xM2-2XAX6 comprises K2SiF6 (indicated herein also as KSiF system or KSiF phosphor or simply KSiF). As indicated above, in another preferred embodiment, M’xM2-2XAX6 comprises KRbSiFe (i.e. r=0.5 and l,n,c,nh,t,g,s,zr,cl,b,i are 0) (herein also indicated as K, Rb system). As indicated above, part of silicon is replaced by manganese (i.e. the formula may also be described as K2Si1-mMnmF6 or KRbSi1-mMnmF6, with m as indicated above, or as KRbSiF6:Mn and K2SiF6:Mn, respectively). As manganese replaces part of a host lattice ion and has a specific function, it is also indicated as “dopant” or “activator”. Hence, the hexafluorosilicate is doped or activated with manganese (Mn4+).2024PF80431

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[0146] In specific embodiments, the luminescent material may comprise (K,Rb)₂SiF₆:Mn⁴⁺. Alternatively or additionally, in embodiments the third luminescent material may comprise K2SiF6:Mn4+. Alternatively or additionally, in embodiments the third luminescent material may comprise K2TiF6:Mn4+. In embodiments, the third luminescent material may comprise K2(Si,Ti)F6:Mn4+. As can be derived from the above, “Si, Ti” may indicate one or more of Si and Ti.

[0147] The luminescent material may also be coated, as also described in WO2013121355A1.

[0148] In specific embodiments, the light guide arrangement may comprise a first luminescent material, wherein the first luminescent material may comprise (may especially be) a luminescent material of the type M’xM2-2xAX6: Mn4+(see also above), wherein M’ comprises an alkaline earth cation, M comprises a monovalent cation, and x is in the range of 0-1, wherein A comprises a tetravalent cation, comprising one or more of silicon, titanium, and germanium, wherein X comprises a monovalent anion, at least comprising fluorine. Note that the phrase luminescent material of the type M’xM2-2xAX6: Mn4+, and similar phrases, may refer to a (first) luminescent material consisting of one type of such (type of) luminescent material, such a e.g. K2TiF6:Mn4+ or K2SiF6:Mn4+, but may also refer to a (first) luminescent material consisting of different types of such (type of) luminescent material, such as e.g. K2TiF6:Mn4+ and K2SiF6:Mn4+. Especially, in embodiments each first luminescent material may be configured to generate first luminescent material light having a first centroid wavelength (λc₁) selected from the above indicated wavelength range (such as selected from the wavelength range of 610-650 nm).

[0149] Especially, the (first) luminescent material may be configured to convert at least part of the device light downstream from the light in-coupling area into (first) luminescent material light.

[0150] Further, in specific embodiments the first luminescent material light may have a first centroid wavelength (λc₁) selected from the range of 600-660 nm, more especially selected from the (wavelength) range of 610-650 nm. In more specific embodiments the first luminescent material light may have a first centroid wavelength (λc₁) selected from the range of 620-640 nm, more especially selected from the (wavelength) range of Alternatively or additionally, in embodiments the first luminescent material light may comprise at least one emission band having a first full width at half maximum FWHM₁ of ≤ 45 nm. As M’XM2-2xAXe: Mn4+type luminescent materials are line emitters, this may especially (at least) apply to such luminescent materials.2024PF80431

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[0152] Further, in embodiments the light guide arrangement may comprise a first particulate material embedded in a first light transmissive material over at least part of the first dimension (DI). Embodiments of light transmissive materials have been described above. The light transmissive material facilitates total internal reflection, and thus distribution of the incoupled device light over the light guide arrangement. However, the presence of particulate material may also facilitate outcoupling of the device light from the light guide arrangement, either via scattering or via conversion (wherein the device light is converted into first luminescent material light and the first luminescent material light outcoupled) (see further also below).

[0153] In embodiments, the first particulate material may comprise at least part of the first luminescent material. Hence, device light propagating through the light transmissive material may, when reaching a particle of the first particulate material, be scattered or converted. However, part of the device light may also be transmitted by a particle of the first particulate material. Scattering and / or transmission may depend upon an angle under which the device light is incident on a particle (of the first particulate material) as well as on an index of refraction difference between the particle and the surrounding light transmissive material.

[0154] In specific embodiments, the first particulate material may have a difference in refractive index with respect to the first light transmissive material of at least 0.02, such as at least 0.05, like in specific embodiments at least 0.1. The refractive index may especially be determined at the centroid wavelength (kdc) of the device light.

[0155] As the first particulate material may be distributed over at least part of the first dimension (DI), the first luminescent material may be distributed over at least part of the first dimension (DI). Hence, in further embodiments the first luminescent material may (thus) be distributed over at least part of the first dimension (DI) such that during operation of the light generating device, first luminescent material light may be generated and may emanate from the light out-coupling area of the light guide arrangement over at least part of the first dimension (DI).

[0156] The light guide arrangement may comprise a light transmissive body, with the particulate material embedded therein. In specific embodiments, the body may essentially consist of a light transmissive entity, without coating and / or without cladding. For instance, the light guide arrangement may comprise a glass fiber or polymeric fiber, or glass plate or polymeric plate. In other embodiments, however, such fiber or plate may be provided with a cladding and / or coating. In embodiments, a cladding (in optical (fiber) applications) is one or2024PF80431

[0157] 27

[0158] more layers of materials of lower refractive index in intimate (especially physical) contact with a core material of higher refractive index.

[0159] When the light guide arrangement comprises a light transmissive core and a cladding and / or coating, then the first particulate material may be comprised by the cladding and / or coating, respectively. In further embodiments, the core may essentially not comprise any first luminescent material (and especially in embodiments also no first particulate material). However, other embodiments are herein not excluded. Hence, in specific embodiments the light guide arrangement may comprise a body, wherein the body comprises a light transmissive core, wherein the light transmissive core comprises a light transmissive core material. In further specific embodiments, the body may further comprise a light transmissive cladding at least partially enclosing the light transmissive core over at least part of the first dimension (DI), wherein the light transmissive cladding comprises the first light transmissive material and at least part of the first particulate material. In embodiments, the light transmissive core material and the first light transmissive material may be the same material. In other embodiments, they may differ, especially they may differ in such a way that the light transmissive core material has a higher index of refraction than the first light transmissive material (comprised by the cladding). By using a lower index cladding, total internal reflection is promoted. However, by introducing the particulate material in the cladding, outcoupling may be promoted, as light propagating in the core may escape from the core via scattering or conversion when a particle of the particulate material in the cladding is in (optical contact) with the core. Hence, in embodiments the body may thus further comprise a light transmissive cladding at least partially enclosing the light transmissive core over at least part of the first dimension (DI), wherein the light transmissive cladding comprises the first light transmissive material and at least part of the first particulate material, whereby the first luminescent material may be distributed over at least part of the first dimension (DI). Hence, in embodiments device light may be guided through the core (by TIR), and coupled out by the first particulate material in the cladding.

[0160] Instead of a cladding, or in addition to a cladding, the light guide arrangement may further comprise a coating layer at least partially enclosing the body over at least part of the first dimension (DI). Especially, in such embodiments the coating layer may comprise a light transmissive coating material. Further, in such embodiments the coating layer may comprise at least part of the first particulate material (comprising at least part of the (first) luminescent material) embedded in the light transmissive coating material of the coating layer. The light transmissive coating material may have an index of refraction lower than the2024PF80431

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[0162] optional cladding and / or lower than the light transmissive core material. In embodiments, wherein the light guide arrangement comprises a cladding and a coating, the coating may enclose the cladding over at least part of the first dimension (DI).

[0163] In embodiments, the cladding may be over at least 90%, such as more especially at least 95%, more especially 100% of the first dimension (DI). In specific embodiments, the cladding may define the (entire) light outcoupling area.

[0164] In embodiments wherein the light guide arrangement comprises a coating layer, like in embodiments with or without a cladding, but when comprising a cladding, then enclosing the cladding over at least part of the first dimension (DI), the coating layer may be over at least 90%, such as more especially at least 95%, more especially 100% of the first dimension (DI). In specific embodiments, the coating layer may define the (entire) light outcoupling area.

[0165] In embodiments, the coating layer may comprise at least part of the first luminescent material. Hence, in embodiments the light guide arrangement further comprises a coating layer at least partially enclosing the body over at least part of the first dimension (DI); wherein the coating layer comprises at least part of the first particulate material (and optionally a light transmissive coating material), whereby the first luminescent material may be distributed over at least part of the first dimension (DI).

[0166] The particles of the particulate material comprising at least part of the first luminescent material may in embodiments comprise particles that essentially consist of the first luminescent material, and may in other embodiments comprises core-shell particles, comprising a core comprising at least part of the first luminescent material and a shell that (at least partially) encloses the (luminescent) core. Such shell may be relatively thin. Further, such shell may especially be transmissive for the luminescent material light. The first luminescent material, or the core essentially consisting of the first luminescent material may have a first index of refraction nl. The optional particle shell, comprising shell material, may have a second index of refraction n2. Further, the first light transmissive material may have a third index of refraction n3.

[0167] Hence, in embodiments the first luminescent material may have a first index of refraction nl, wherein the first particulate material may comprise particles, wherein the particles comprise a particle core, comprising the first luminescent material, and a particle shell at least partially enclosing the particle core, wherein the particle shell comprises shell material, wherein the shell material comprises a second index of refraction n2. Especially, in such embodiments n2>nl+0.01, like n2>nl+0.02. Yet, in embodiments n2>nl+0.05, more2024PF80431

[0168] 29

[0169] especially n2>nl+0.1. Further, in specific embodiments one or more of the following may apply: (a) n3>nl+0.01, more especially n3>nl+0.02, like especially n3>nl+0.05, like in specific embodiments n3>nl+0.1 or (b) |n3-n2|>0.01, more especially |n3-n2|>0.02, like especially |n3-n2|>0.05, like in specific embodiments |n3-n2|>0.1. Further, in specific embodiments |n3-n2| > |n3-nl|.

[0170] Note that KSiF type luminescent materials may have refractive indices (indices of refraction) in the range of about 1.29-1.40 (at 590 nm), such as in the range of about 1.32-1.37, especially in the range of about 1.34-1.35. As KSiF type luminescent materials may have a relatively low index of refraction (nl), particles thereof may not be very well suited for light outcoupling. Hence, in embodiments core-shell particles may be used, with the core comprising first luminescent material, and the shell comprising a light transmissive material having a higher index of refraction (n2) such that it may improve light outcoupling. Especially, the shell material may be transparent for both device light and first luminescent material light.

[0171] In specific embodiments, n3>nl+0.15, such as n3>nl+0.2, like in embodiments or n3>nl+0.25. Further, in embodiments n3-n2>0.1, such as n3-n2>0.15, like in embodiments or n3-n2>0.2. In alternative embodiments, however, n2-n3>0.1, such as n2-n3>0.15, like in embodiments n2-n3>0.2 (such as in specific embodiments n2-n3>0.25). Such embodiments may improve light outcoupling. In embodiments, a (polymer) matrix may be chosen such that the refractive index mismatch with the phosphor particle or its shell may be relatively large, such as a difference of at least 0.1.

[0172] Differences between refractive indices may in embodiments be at maximum about 0.8, such as at maximum about 0.7.

[0173] In embodiments, the first particulate material may have a number averaged particle size selected from the range of 10-1000 nm. Smaller number averaged particle sizes, like e.g. below 500 nm, such as below 400 nm, may lead to lower scattering. This may e.g. be desirable in longer light guide arrangements. In embodiments, the first particulate material may have a number averaged particle size selected from the range of at least 50 nm, such as at least 100n, such as a number averaged particle size selected from the range of 100-800 nm, such as selected from the range of 200-700 nm, like in embodiments selected from the range of 300-600 nm. Smaller number averaged particle sizes, like e.g. below 500 nm, may thus also be possible. This may improve outcoupling of the device light, as the particle size may be in the wavelength range of the device light. Especially, the number averaged particle size2024PF80431

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[0175] may be determined with an optical method. For instance, the number averaged particle size may be measured with an electron microscope.

[0176] In order to reduce outcoupling closer to the light generating device and promote outcoupling more remote from the light generating device, the concentration of the first particulate material over the first dimension (DI) may vary. In specific embodiments, the first particulate material may have a local concentration in the first light transmissive material which over at least part of the first dimension (DI) increases with increasing distance (d) from the light in-coupling area. Such increase may be gradual or may be stepwise (especially with multiple steps). This may improve a homogeneous outcoupling of the first luminescent material light and / or device light.

[0177] In embodiments, the concentration of the manganese dopant in the first luminescent material may be chosen relatively low. A high dopant concentration may lead to a higher outcoupling. Especially when using longer light guide arrangements, the dopant concentration may be relatively low, whereas when using shorter light guide arrangements, the dopant concentration may be higher. In specific embodiments, the first luminescent material of the type M’xM2-2xAX6: Mn4+may be M’xM2-2xAi-mMnmX6, wherein m<0.05. In embodiments, m may be at least 0.0001, like 0.0005, such as more especially at least 0.001.

[0178] In embodiments, the light generating system may comprise a second luminescent material. Especially, the second luminescent material may also convert at least part of the device light, but thereby generating second luminescent material light that differs in spectral power distribution from the first luminescent material light. For instance, they may have different colors and / or different color points.

[0179] In specific embodiments, colors or color points of a first type of light and a second type of light may be different when the respective color points of the first type of light and the second type of light differ with at least 0.01 for u’ and / or with at least 0.01 for v’, even more especially at least 0.02 for u’ and / or with at least 0.02 for v’. In yet more specific embodiments, the respective color points of first type of light and the second type of light may differ with at least 0.03 for u’ and / or with at least 0.03 for v’. Here, u’ and v’ are color coordinates of the light in the CIE 1976 UCS (uniform chromaticity scale) diagram. Spectral power distributions of different sources of light having centroid wavelengths differing at least 10 nm, such as at least 20 nm, or even at least 30 nm may be considered different spectral power distributions, e.g. different colors. In general, the differences in centroid wavelengths will not be larger than about 400 nm, such as not more than 350 nm. In embodiments, the second luminescent material light may be green light or yellow light. Hence, in embodiments2024PF80431

[0180] 31

[0181] the second luminescent material light may have a second centroid wavelength (λc₂) selected from the range of 490-620 nm, more especially 490-600 nm, like in embodiments selected from the wavelength range of 500-590 nm. Further, in embodiments (λdc + 10 nm) ≤ λc₂ ≤ (λc₁ + 10 nm), like (λdc + 20 nm) ≤ λc₂ ≤ (λc₁ + 20 nm), more especially (λdc + 30 nm) ≤ λc₂ ≤ (λc₁ + 30 nm).

[0182] Note that the term “second luminescent material”, and similar terms, may refer to a second luminescent material consisting of a single type of luminescent material, such a e.g. Y₃Al₅O₁₂:Ce3+or Lu₃Al₅O₁₂:Ce3+but may also refer to a (second) luminescent material consisting of different types (second) luminescent material, such as e.g. Y₃Al₅O₁₂:Ce3+and Lu3AlsOi2: Ce3+. Especially, in embodiments each second luminescent material may be configured to generate second luminescent material light having a second centroid wavelength (λc₂) selected from the above indicated wavelength range (such as selected from the wavelength range of 490-620 nm).

[0183] At least part of the second luminescent material may be comprised by the first particulate material. Alternatively or additionally, at least part of the second luminescent material may be comprised by a second particulate material. Basically, many of the embodiments described in relation to the first luminescent material, may also apply to the second luminescent material, of course except for the intrinsic differences between the luminescent materials, as will be clear to a person skilled in the art. Hence, at least part of the second luminescent material may be comprised by the core and / or at least part of the second luminescent material may be comprised by the optional cladding and / or at least part of the second luminescent material may be comprised by the optional coating layer. Further, it may be possible that at least part of the first luminescent material is comprised by the optional coating layer and at least part of the second luminescent material is comprised by the same optional coating layer and / or at least part of the second luminescent material is comprised by another optional coating layer.

[0184] Therefore, in embodiments the light guide arrangement may comprise a second luminescent material distributed over at least part of the first dimension (DI), wherein the second luminescent material may be configured to convert at least part of the device light downstream from the light in-coupling area into second luminescent material light, such that during operation of the light generating device, second luminescent material light may be generated and emanates from the light out-coupling area (of the light guide arrangement) over at least part of the first dimension (DI).2024PF80431

[0185] 32

[0186] Hence, in embodiments the light generating system may (thus) further comprise the light transmissive cladding, wherein the light transmissive cladding comprises at least part of the second luminescent material. Hence, in embodiments the body may thus further comprise a light transmissive cladding at least partially enclosing the light transmissive core over at least part of the first dimension (DI), wherein the light transmissive cladding comprises the first light transmissive material and at least part of the second luminescent material, wherein by the second luminescent material may be distributed over at least part of the first dimension (DI). Note that the body may also comprise a second cladding, enclosing the first cladding over at least part of the first dimension (DI), or being configured between the light transmissive core and the first cladding over at least part of the first dimension (DI), (wherein optionally the first cladding comprises at least part of the first luminescent material,) wherein the second cladding comprises at least part of the second luminescent material, wherein by the second luminescent material may be distributed over at least part of the first dimension (DI). Hence, the cladding may in embodiments comprise a multi-layer cladding, wherein in specific embodiments one or more of the following may apply: (i) at least one of the cladding layers comprises at least part of the first luminescent material, and (ii) at least one of the cladding layers comprises the second luminescent material.

[0187] Alternatively or additionally, the light generating system may further comprising the coating layer as described above, wherein the coating layer comprises at least part of the second luminescent material over at least part of the first dimension (DI).

[0188] Alternatively or additionally, the coating layer may be a multi-layer coating, wherein in specific embodiments one or more of the following may apply: (i) at least one of the layers comprises at least part of the first luminescent material, and (ii) at least one of the layers comprises the second luminescent material. Further, in specific embodiments the first luminescent material and the second luminescent material may be comprised by either different layers or the same layer of the multi-layer coating.

[0189] In embodiments, the first luminescent material and / or the second luminescent material may, especially in specific embodiments the second luminescent material may, comprises one or more of (i) a divalent europium comprising nitride luminescent material, and (ii) a luminescent material of the type M1-xLi3-2yAl1+2y-zSizO4-4y-zN4y+z:Eux, wherein M comprises one or more of Mg, Ba, Sr, and Ca, wherein 0 < x < 0.1, wherein 0 < y < 1, and wherein 0 < z < 0.1. Alternatively or additionally, the first luminescent material and / or the second luminescent material, especially in specific embodiments the second luminescent2024PF80431

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[0191] material, comprises one or more of (iii) a divalent europium comprising thiogallate, (iv) a divalent europium comprising thioaluminate, (v) a divalent europium comprising silicate, and (vii) a luminescent material of the type Si6-nAlnOnN8-n:Eu2+, wherein 0 < n < 4.2.

[0192] The term “divalent europium comprising thiogallate” may herein refer to a luminescent material of the type MwAuXv:Eu2+1-w, wherein M comprises one or more of Mg, Sr, Ca, and Ba, wherein A comprises Ga and optionally one or more of Al, boron (B), In, Sc, Lu, and Y, wherein X comprises one or more of S, Se, O, and tellurium (Te), (such as especially at least S), wherein 0.01 < w < 0.99, wherein 2 < u < 4, and wherein 4 < v < 7. In embodiments, X in MwAuXv:Eu2+1-wmay especially comprise one or more of (i) S, (ii) Se, and (iii) S and Se. Additionally or alternatively, the third luminescent material may comprise (such as be) a divalent europium comprising thioaluminate. The term “divalent europium comprising thioalluminate” may herein refer to a luminescent material of the type MwAuXv:Eu2+1-w, wherein M comprises one or more of Mg, Sr, Ca, and Ba, wherein A comprises Al and optionally one or more of Ga, boron (B), In, Sc, Lu, and Y, such as at least Al, wherein X comprises one or more of S, Se, O, and tellurium (Te), (such as especially at least S), wherein 0.01 < w < 0.99, wherein 2 < u < 4, and wherein 4 < v < 7. The third luminescent material may in specific embodiments comprise (a mixture of) a divalent europium comprising thiogallate and a divalent europium comprising thioaluminate. Further, the third luminescent material may comprise Mw(GatAl1-t)uXv:Eu2+1-w, wherein M comprises one or more of Mg, Sr, Ca, and Ba, wherein X comprises one or more of S, Se, O, and tellurium (Te), (such as especially at least S), wherein 0.01 < w < 0.99, wherein 2 < u < 4, wherein 4 < v < 7, and wherein 0 < t < 1. Additionally or alternatively, the third luminescent material may comprise (such as be) a divalent europium comprising silicate. Especially, the divalent europium comprising silicate may comprise, such as be, (Sr1-xBax)2SiO4:Eu2+, wherein 0 < x < 1, such as especially 0 < x < 1. In specific embodiments, x = 0.5 may apply, and the divalent europium comprising silicate may comprise, such as be, SrBaSiO4: Eu2+.

[0193] During operation of the light generating system, more especially during operation of the light generating device, light may escape from the light guide arrangement via the light out-coupling area. This light emanates away from the light guide arrangement and may also be indicated as arrangement light. The arrangement light may comprise the first luminescent material light, optionally device light, and optionally second luminescent material light. In embodiments, especially when the arrangement light comprises the first luminescent material light, device light, and second luminescent material light, this arrangement light may be white light. For instance, the arrangement light may in2024PF80431

[0194] 34

[0195] embodiments have a CCT of at least 1500 K, such as at least 1700 K, like at least 1800 K, and in specific embodiments at least 2000 K. Further, this arrangement light may in embodiments have a CCT of at maximum 20000 K, such as at maximum 12000 K, like at maximum 8000 K, and in specific embodiments at maximum 6500 K. Yet, the arrangement light may in embodiments have a CRI of at least 60, such as at least 65, like in specific embodiments at least 70. Furthermore, in embodiments the CRI of the arrangement light may be at least 75, such as at least about 80 (or even higher). Hence, in specific embodiments the arrangement light may comprise device light, first luminescent material light, and second luminescent material light, and may be white light having a correlated color temperature selected from the range of 2000-6500 K and a color rendering index of at least 70.

[0196] Hence, in specific embodiments the light generating system may be configured to generate arrangement light, wherein in an operational mode of the light generating system, the arrangement light has a spectral power distribution in the 380-780 nm wavelength range, wherein xl% of the spectral power is provided by the device light ((also) escaping from the light guide arrangement via the light out-coupling area (of the light guide arrangement) (over at least part of the first dimension (DI))), x2% of the spectral power is provided by the first luminescent material light, and x3% of the spectral power is provided by the second luminescent material light. In embodiments, xl% may be at least 1%, such as at least 2%. Further, in embodiments x2% may be at least 20%, such as at least 30%. Yet, in embodiments x3% may be 0% or larger. Further, in embodiments xl% may be at maximum 35%, such as at maximum 25%. Yet further, in embodiments x2% may be at maximum 99%, such as at maximum 98%. Further, in embodiments x3% may be at maximum 65%, such as at maximum 58%. Especially, in embodiments 2≤x1≤25, 30≤x2≤98, and 0≤x3≤58. Further, especially xl%+x2%+x3%=100% may apply. Note that in embodiments the arrangement light may be white light. In such embodiments, 0<x3<58, like in specific embodiments 5<x3<58.

[0197] The arrangement light may thus comprise device light. Especially, at least 90%, such as at least 95%, more especially at least 98%, most especially 100% of the device light comprised by the arrangement light originates from device light incoupled via the light in-coupling area and (subsequently) escaping from the light guide arrangement via the light out-coupling area. Hence, in embodiments any device light comprised by the arrangement light may be the device light incoupled via the light in-coupling area and (subsequently) escaping from the light guide arrangement via the light out-coupling area. Likewise, any luminescent material light comprised by the arrangement light may only originate from the2024PF80431

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[0199] conversion of device light incoupled via the light in-coupling area and converted by the (first and optional second) luminescent material comprised by the light guide arrangement.

[0200] Hence, this may imply in embodiments that device light of the light generating device may only escape from the light guide arrangement via transmission by the light guide arrangement. Therefore, in embodiments the arrangement light (and in specific embodiments, see also below, the system light,) may not comprise device light other than device light that has escaped from the light guide arrangement via transmission by the light guide arrangement.

[0201] Especially, the light generating system may be configured to generate system light. In embodiments, the system light produced by the light generating system during operation of the light generating system may (essentially) consist of the arrangement light. In specific embodiments, in an operational mode of the light generating system, the system light may have a spectral power distribution in the 380-780 nm wavelength range wherein xl% of the spectral power is provided by the device light ((also) escaping from the light guide arrangement via the light out-coupling area (of the light guide arrangement)(over at least part of the first dimension (DI))), x2% of the spectral power is defined by the first luminescent material light, and x3% of the spectral power is defined by the second luminescent material light, wherein 2≤x1≤25, 30≤x2≤98, and 0≤x3≤58, and wherein especially xl+x2+x3=100. More especially, in embodiments the light generating system may be configured to generate system light, wherein in an operational mode of the light generating system, the system light has a spectral power distribution in the 380-780 nm wavelength range wherein xl% of the spectral power is defined by the device light ((also) escaping from the light guide arrangement via the light out-coupling area (of the light guide arrangement) (over at least part of the first dimension (DI))), x2% of the spectral power is defined by the first luminescent material light, and x3% of the spectral power is defined by the second luminescent material light as defined herein, wherein 2≤x1≤25, 30≤x2≤98, and 0≤x3≤58, and wherein xl+x2+x3=100; and wherein the system light comprising device light, first luminescent material light, and second luminescent material light is white light having a correlated color temperature selected from the range of 2000-6500 K and a color rendering index of at least 70 (see further also above in relation to arrangement light for specific embodiments).

[0202] Note that the system light in other embodiments may comprise arrangement light and, in an operational mode of the light generating system, light of one or more other sources of light (in embodiments wherein the light generating system comprises one or more other sources of light). Such one or more other sources of light may be indicated as one or2024PF80431

[0203] 36

[0204] more second light generating devices and may not be configured in a light receiving relationship with (the light in-coupling are) of the light guide arrangement. However, such optional additional sources of light are herein further not discussed.

[0205] Especially in view of M’xM2-2xAX6: Mn4+, it may be desirable to provide device light having spectral power in the 400-425 nm wavelength range and / or in the wavelength range of 475-490 nm. A low absorption of the device light may facilitate that the device light propagates further through the light guide arrangement. This may be provided with a single light generating device having multiple peaks, or by using a plurality of (first) light generating devices, wherein one or more of the plurality of (first) light generating devices generate device light having a device light centroid wavelength (kdc) in the wavelength range of 400-425 nm and / or wherein one or more of the plurality of (first) light generating devices generate device light having a device light centroid wavelength (kdc) in the wavelength range of 475-490 nm. When at least two first light generating devices with different centroid wavelengths are available, this may also allow a control of the spectral power distribution, especially when also the second luminescent material is available, as the first luminescent material and the second luminescent material may have different excitation characteristics. Hence, in specific embodiments the light generating system may comprise at least two light generating devices, wherein the light in-coupling area may be configured in a light receiving relationship with the at least two light generating devices, wherein the device light centroid wavelengths (λdc) of the device light of the at least two light generating devices are selected from the wavelength range of 400-425 nm and / or from the wavelength range of 475-490 nm. In specific embodiments, one or more first light generating devices may have device light centroid wavelengths (λdc) selected from the wavelength range of 400-425 nm and one or more other first light generating devices may have device light centroid wavelengths (λdc) selected from the wavelength range of 475-490 nm.

[0206] In embodiments, the first luminescent material may be comprised by the light guide arrangement over at least 60%, more especially at least 70%, such as at least 80%, like in specific embodiments at least 90%, of the first dimension (DI). For instance, would the light guide arrangement be divided in n parts of equal volume and equal length along the first dimension (DI), then at least 60%, more especially at least 70%, such as at least 80%, like in specific embodiments at least 90%, of the n parts may comprise at least part of the first luminescent material. For instance, n may be selected from the range of 10-1000, like 10-100.

[0207] As indicated above, in embodiments the first luminescent material may be distributed over at least part of the first dimension (DI) such that during operation of the light2024PF80431

[0208] 37

[0209] generating device, first luminescent material light is generated and emanates from the light out-coupling area of the light guide arrangement over at least part of the first dimension (DI). In analogy of the above, would the light guide arrangement be divided in n parts of equal volume and equal length along the first dimension (DI), then from at least 60%, more especially from at least 70%, such as from at least 80%, like in specific embodiments from at least 90%, of the n parts first luminescent material light may emanate. For instance, n may be selected from the range of 10-1000, like 10-100.

[0210] Further, as indicated above, in embodiments the light generating system may be configured such that during operation of the light generating device at least part of the device light propagates through the light guide arrangement over at least part of the first dimension (DI) while being totally internally reflected multiple times and subsequently coupled out from the light guide arrangement and emanating from the light out-coupling area of the light guide arrangement over at least part of the first dimension (DI). In analogy of the above, would the light guide arrangement be divided in n parts of equal volume and equal length along the first dimension (DI), then from at least 60%, more especially from at least 70%, such as from at least 80%, like in specific embodiments from at least 90%, of the n parts first device light may emanate. For instance, n may be selected from the range of 10-1000, like 10-100.

[0211] In embodiments, the phrase “totally internally reflected multiple times” or “total internal reflection”, and similar phrases, especially in relation to device light, may imply that at least part of the device light may be reflected at least 10 times. Especially, at least 90% of the device light coupled into the light guide arrangement via the light incoupling area may internally be reflected at least two times, like at least five times. Here, the percentage may especially be based on a percentage of the spectral power of the device light that is incoupled (or on the number of photons).

[0212] In embodiments wherein the second luminescent material may be comprised by the light guide arrangement, the second luminescent material may be comprised by the light guide arrangement over at least 60%, more especially at least 70%, such as at least 80%, like in specific embodiments at least 90%, of the first dimension (DI). For instance, would the light guide arrangement be divided in n parts of equal volume and equal length along the first dimension, then at least 60%, more especially at least 70%, such as at least 80%, like in specific embodiments at least 90%, of the n parts may comprise the second luminescent material. Again, n may for instance be selected from the range of 10-1000, like 10-100.2024PF80431

[0213] 38

[0214] As indicated above, in embodiments the second luminescent material may be distributed over at least part of the first dimension (DI) such that during operation of the light generating device, second luminescent material light is generated and emanates from the light out-coupling area of the light guide arrangement over at least part of the first dimension (DI). In analogy of the above, would the light guide arrangement be divided in n parts of equal volume and equal length along the first dimension (DI), then from at least 60%, more especially from at least 70%, such as from at least 80%, like in specific embodiments from at least 90%, of the n parts second luminescent material light may emanate. For instance, n may be selected from the range of 10-1000, like 10-100.

[0215] The light guide arrangement may have an external surface comprising the light out-coupling area. In embodiments, at least 60%, more especially at least 70%, like more especially at least 80%, such as selected from the range of 80-99.99% of the external surface may be light out-coupling area. For light guide plates this may e.g. be up to about 99%, but for fibers the percentage may thus be even higher. Note, however, that higher or lower percentages than 99.99% may be possible, but especially at least about 80%.

[0216] In analogy to the above, would the light out-coupling area be divided in n parts of equal area, then from at least 60%, more especially from at least 70%, such as from at least 80%, like in specific embodiments from at least 90%, of the n parts first luminescent material light second luminescent material light may emanate. Likewise, would the light out-coupling area be divided in n parts of equal area, then, in embodiments, from at least 60%, more especially from at least 70%, such as from at least 80%, like in specific embodiments from at least 90%, of the n parts second luminescent material light second luminescent material light may emanate. Likewise, would the light out-coupling area be divided in n parts of equal area, then, in embodiments, from at least 60%, more especially from at least 70%, such as from at least 80%, like in specific embodiments from at least 90%, of the n parts device light may emanate. For instance, n may be selected from the range of 10-1000, like 10-100.

[0217] Herein, 80% from 10 parts means 8 parts; similarly, 90% from 100 parts means 90 parts, etc.

[0218] Yet, in embodiments the light generating system may further comprise an optical arrangement configured in an optical path between the light generating device and the light in-coupling area, wherein the optical arrangement may be configured to facilitate incoupling of the device light into the light guide arrangement. In embodiments, the optical arrangement may comprise one or more lenses, e.g. to focus the device light and / or to collimate the device light.2024PF80431

[0219] 39

[0220] The light generating system may be part of or may be applied in e.g. office lighting systems, household application systems, shop lighting systems, home lighting systems, accent lighting systems, spot lighting systems, theater lighting systems, fiber-optics application systems, projection systems, self-lit display systems, pixelated display systems, segmented display systems, warning sign systems, medical lighting application systems, indicator sign systems, decorative lighting systems, portable systems, automotive applications, (outdoor) road lighting systems, urban lighting systems, greenhouse lighting systems, horticulture lighting, digital projection, or LCD backlighting. The light generating system (or luminaire) may be part of or may be applied in e.g. optical communication systems or disinfection systems.

[0221] The term “white light”, and similar terms, herein, is known to the person skilled in the art. It may especially relate to light having a correlated color temperature (CCT) between about 1800 K and 20000 K, such as between 2000 and 20000 K, especially 2700-20000 K, for general lighting especially in the range of about 2000-7000 K, such as in the range of 2700 K and 6500 K. In embodiments, e.g. for backlighting purposes, or for other purposes, the correlated color temperature (CCT) may especially be in the range of about 7000 K and 20000 K. Yet further, in embodiments the correlated color temperature (CCT) is especially within about 15 SDCM (standard deviation of color matching) from the BBL (black body locus), especially within about 10 SDCM from the BBL, even more especially within about 5 SDCM from the BBL. The terms “visible”, “visible light” or “visible emission” and similar terms refer to light having one or more wavelengths in the range of about 380-780 nm. The terms “light” and “radiation” are herein interchangeably used, unless clear from the context that the term “light” only refers to visible light. The terms “light” and “radiation” may thus refer to UV radiation, visible light, and IR radiation. In specific embodiments, especially for lighting applications, the terms “light” and “radiation” refer to (at least) visible light. The terms “violet light” or “violet emission”, and similar terms, may especially relate to light having a wavelength in the range of about 380-440 nm. In specific embodiments, the violet light may have a centroid wavelength in the 380-440 nm range. The terms “blue light” or “blue emission”, and similar terms, may especially relate to light having a wavelength in the range of about 440-490 nm (including some violet and cyan hues). In specific embodiments, the blue light may have a centroid wavelength in the 440-490 nm range. The terms “green light” or “green emission”, and similar terms, may especially relate to light having a wavelength in the range of about 490-560 nm. In specific embodiments, the green light may have a centroid wavelength in the 490-560 nm range. The terms “yellow2024PF80431

[0222] 40

[0223] light” or “yellow emission”, and similar terms, may especially relate to light having a wavelength in the range of about 560-590 nm. In specific embodiments, the yellow light may have a centroid wavelength in the 560-590 nm range. The terms “orange light” or “orange emission”, and similar terms, may especially relate to light having a wavelength in the range of about 590-620 nm. In specific embodiments, the orange light may have a centroid wavelength in the 590-620 nm range. The terms “red light” or “red emission”, and similar terms, may especially relate to light having a wavelength in the range of about 620-780 nm, such as 620-750 nm. In specific embodiments, the red light may have a centroid wavelength in the 620-780 nm range, such as 620-750 nm. The terms “cyan light” or “cyan emission”, and similar terms, especially relate to light having a wavelength in the range of about 490-520 nm. In specific embodiments, the cyan light may have a centroid wavelength in the 490-520 nm range. The terms “amber light” or “amber emission”, and similar terms, may especially relate to light having a wavelength in the range of about 585-605 nm, such as about 590-600 nm. In specific embodiments, the amber light may have a centroid wavelength in the 585-605 nm range. The phrase “light having one or more wavelengths in a wavelength range” and similar phrases may especially indicate that the indicated light (or radiation) has a spectral power distribution with at least intensity or intensities at these one or more wavelengths in the indicate wavelength range. For instance, a blue emitting solid state light source will have a spectral power distribution with intensities at one or more wavelengths in the 440-490 nm wavelength range.

[0224] The term “operational mode” especially refers to a way in which a (light) source, device, or system operates. For instance, when a device, source, of system can only execute a single action, (e.g. generating white light), then there may be a single operational mode. However, would the (light) source, device, or system be controllable (e.g. generating white light or colored light, in dependence of controllable settings), the (light) source, device, or system may have different operational modes.

[0225] The term “controlling” and similar terms especially refer at least to determining the behavior or supervising the running of an element. Hence, herein “controlling” and similar terms may e.g. refer to imposing behavior to the element (determining the behavior or supervising the running of an element), etc., such as e.g. measuring, displaying, actuating, opening, shifting, changing temperature, etc.. Beyond that, the term “controlling” and similar terms may additionally include monitoring. Hence, the term “controlling” and similar terms may include imposing behavior on an element and also imposing behavior on an element and monitoring the element. The controlling of the element2024PF80431

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[0227] can be done with a control system, which may also be indicated as “controller”. The control system and the element may thus at least temporarily, or permanently, functionally be coupled. The element may comprise the control system. In embodiments, the control system and element may not be physically coupled. Control can be done via wired and / or wireless control. The term “control system” may also refer to a plurality of different control systems, which especially are functionally coupled, and of which e.g. one control system may be a master control system and one or more others may be slave control systems. A control system may comprise or may be functionally coupled to a user interface.

[0228] The control system may also be configured to receive and execute instructions from a remote control. In embodiments, the control system may be controlled via an App on a device, such as a portable device, like a Smartphone or I-phone, a tablet, etc.. The device is thus not necessarily coupled to the lighting system, but may be (temporarily) functionally coupled to the lighting system.

[0229] Hence, in embodiments the control system may (also) be configured to be controlled by an App on a remote device. In such embodiments the control system of the lighting system may be a slave control system or control in a slave mode. For instance, the lighting system may be identifiable with a code, especially a unique code for the respective lighting system. The control system of the lighting system may be configured to be controlled by an external control system which has access to the lighting system on the basis of knowledge (input by a user interface of with an optical sensor (e.g. QR code reader) of the (unique) code. The lighting system may also comprise means for communicating with other systems or devices, such as on the basis of Bluetooth, Thread, WIFI, LiFi, ZigBee, BLE or WiMAX, or another wireless technology.

[0230] The system, or apparatus, or device may execute an action in a “mode” or “operation mode” or “mode of operation” or “operational mode”. The term “operational mode may also be indicated as “controlling mode”. Likewise, in a method an action or stage, or step may be executed in a “mode” or “operation mode” or “mode of operation” or “operational mode”. This does not exclude that the system, or apparatus, or device may also be adapted for providing another controlling mode, or a plurality of other controlling modes. Likewise, this may not exclude that before executing the mode and / or after executing the mode one or more other modes may be executed.

[0231] However, in embodiments a control system may be available, that is adapted to provide at least the controlling mode. Would other modes be available, the choice of such modes may especially be executed via a user interface, though other options, like executing a2024PF80431

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[0233] mode in dependence of a sensor signal or a (time) scheme, may also be possible. The operation mode may in embodiments also refer to a system, or apparatus, or device, which can only operate in a single operation mode (i.e. “on”, without further tunability).

[0234] Hence, in embodiments, the control system may control in dependence of one or more of an input signal of a user interface, a sensor signal (of a sensor), and a timer. The term “timer” may refer to a clock and / or a predetermined time scheme.

[0235] In yet a further aspect, the invention also provides a lamp or a luminaire comprising the light generating system as defined herein. The luminaire may further comprise a housing, optical elements, louvres, etc. etc... The lamp or luminaire may further comprise a housing enclosing the light generating system. The lamp or luminaire may comprise a light window in the housing or a housing opening, through which the system light may escape from the housing. In yet a further aspect, the invention also provides a projection device comprising the light generating system as defined herein. Especially, a projection device or “projector” or “image projector” may be an optical device that projects an image (or moving images) onto a surface, such as e.g. a projection screen. The projection device may include one or more light generating systems such as described herein. Hence, in an aspect the invention also provides a lighting device selected from the group of a lamp, a luminaire, a projector device, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system as defined herein. The lighting device may comprise a housing or a carrier, configured to house or support, one or more elements of the light generating system. For instance, in embodiments the lighting device may comprise a housing or a carrier, configured to house or support one or more of light generating device and the light guide arrangement. In yet a further aspect, the invention also provides a lighting fixture comprising the light generating system as defined herein. Hence, in yet a further aspect, the light generating system may comprise a device selected from the group of a lamp, a luminaire, or a lighting fixture, wherein the lamp, luminaire, or lighting fixture may comprise one or more elements of the light generating system, such as the light generating device and / or the light guide arrangement, and the light generating system may further comprise e.g. a control system configured to control the device. The term “lighting fixture” may refer to a light emitting system like a moving head, a search light, a stage light, etc. Generally these fixtures may have various control options for changing one or more of the direction of the light (e.g. via gimbals or rotary stages), the beam angle / width (e.g. via zoom optics), the beam pattern (e.g. via mechanical selection of a specific aperture that defines a virtual and patterned source for the further projection optics), the color of the2024PF80431

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[0237] light (e.g. via mechanical selection of a certain color filter), and of course the luminous flux, and mostly these are remotely controllable. In embodiments, the lamp or luminaire may be a downlighter or an uplighter. In embodiments, the lamp may comprise a torch. Hence, in yet a further aspect the invention provides a lighting device selected from the group of a lamp and a luminaire comprising the light generating system as defined herein.

[0238] BRIEF DESCRIPTION OF THE DRAWINGS

[0239] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

[0240] Fig. 1-2E schematically depict some embodiments and variants thereon; and Fig. 3 schematically depicts some application embodiments.

[0241] The schematic drawings are not necessarily to scale.

[0242] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0243] Figs. 1-2E schematically depict some embodiments and variants thereof of a light generating system 1000 comprising a light generating device 110 and a light guide arrangement 400. Especially, the light generating device 110 may be configured to generate device light 111 having a device light centroid wavelength (λdc) selected from the range of 380-490 nm. Moreover, in embodiments, the light generating device 110 may comprise a semiconductor-based light generating device. Further, in embodiments, the light guide arrangement 400 may comprise a light in-coupling area 401, a first dimension DI, a second dimension D2, and a light out-coupling area 402 over at least part of the first dimension DI. Moreover, in embodiments, the first dimension DI may be a length. In further embodiments, the second dimension D2 may be a circular equivalent diameter of a cross-sectional area defined perpendicular to the first dimension DI. Yet, in embodiments, D2 / D1≤0.1.

[0244] Furthermore, in embodiments, the light in-coupling area 401 may be configured in a light receiving relationship with the light generating device 110. Furthermore, in embodiments, along at least part of the first dimension DI of the light guide arrangement 400 downstream of the light in-coupling area 401, the light guide arrangement 400 may be at least partly transmissive for the device light 111 coupled into the light guide arrangement 400 via the light in-coupling area 401. Especially, the light guide arrangement 400 may comprise a first luminescent material 210. Further, in embodiments, the first luminescent material 210 may comprise (especially is) a luminescent material of the type M’xM2-2xAX6: Mn4+. Further, in2024PF80431

[0245] 44

[0246] embodiments, M’ may comprise an alkaline earth cation, M may comprise a monovalent cation, and x may be in the range of 0-1. Furthermore, in embodiments, A may comprise a tetravalent cation. The embodiment may comprise one or more of silicon, titanium, and germanium. Especially, X may comprise a monovalent anion, at least comprising fluorine. Especially, the first luminescent material 210 may be configured to convert at least part of the device light 111 downstream from the light in-coupling area 401 into first luminescent material light 211. Especially, the first luminescent material light 211 may have a first centroid wavelength (λc₁) selected from the range of 610-650 nm. Further, in embodiments, the first luminescent material light 211 may comprise at least one emission band having a first full width at half maximum FWHM₁ of ≤ 45 nm. Moreover, in embodiments, wherein the light guide arrangement 400 may comprise a first particulate material 431 embedded in a first light transmissive material 420 over at least part of the first dimension DI. Furthermore, in embodiments, the first particulate material 431 may comprise at least part of the first luminescent material 210. Moreover, in embodiments, wherein the first particulate material 431 may have a difference in refractive index with respect to the first light transmissive material 420 of at least 0.1. Furthermore, in embodiments, wherein the first luminescent material 210 may be distributed over at least part of the first dimension DI such that during operation of the light generating device 110, first luminescent material light 211 may be generated and emanates from the light out-coupling area 402 of the light guide arrangement 400 over at least part of the first dimension DI. Further, in embodiments the light generating device 110 may especially comprise a semiconductor light source, such as one or more of a light emitting diode (LED), a laser diode, or a superluminescent diode.

[0247] Especially, the light generating system 1000 may be configured such that during operation of the light generating device 110 at least part of the device light 111 propagates through the light guide arrangement 400 over at least part of the first dimension DI while being totally internally reflected multiple times and subsequently coupled out from the light guide arrangement 400 and emanates from the light out-coupling area 402 of the light guide arrangement 400 over at least part of the first dimension DI.

[0248] Reference 506 refers to an optional (specular) reflector. Note that in alternative embodiments the light guide arrangement 400 may be irradiated from more than one side. For instance referring to the embodiment of Fig. 1, the light guide arrangement 400 may also be irradiated from the right.

[0249] Furthermore, referring e.g. to Figs-2A, in embodiments, the light guide arrangement 400 may comprise a body 410. Especially, the body 410 may comprise a light2024PF80431

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[0251] transmissive core 415, see e.g. embodiments II- VII. Furthermore, in embodiments, the light transmissive core 415 may comprise a light transmissive core material 417. Especially, the body 410 may further comprise a light transmissive cladding 450 at least partially enclosing the light transmissive core 415 over at least part of the first dimension DI, see e.g. embodiments III, IV, and VI of Fig. 2A

[0252] In embodiments, the light transmissive cladding 450 may comprise the first light transmissive material 420 and at least part of the first particulate material 431, see e.g. embodiments V-VI of Fig. 2a.

[0253] In (other) embodiments, the light guide arrangement 400 may further comprise a coating layer 455 at least partially enclosing the body 410 over at least part of the first dimension DI, see e.g. embodiments II, IV, V, and VII of Fig. 2A. Furthermore, in embodiments, the coating layer 455 may comprise a light transmissive coating material 458. Yet, in embodiments, the coating layer 455 may comprise at least part of the particulate material 4311 (over at least part of the first dimension DI), see e.g. embodiments II, IV, V, and VII of Fig. 2A.

[0254] Referring to Fig. 2A, embodiments II and IV, in specific embodiments, particulate material 434 material may be available, not comprising luminescent material (which converts device light 111). Such particulate material may facilitate outcoupling.

[0255] In embodiments, the first luminescent material 210 may have a first index of refraction nl. Referring to Fig. 2B, in embodiments particles 432 of the particulate material 431 may comprise core-shell particles. Hence, in embodiments the first particulate material 431 may comprise particles 432. Furthermore, in embodiments, the particles may comprise a particle core 433, especially, in embodiments comprising at least part of the first luminescent material 210, and a particle shell 438 at least partially enclosing the particle core 433. In further embodiments, the particle shell 438 may comprise shell material 439. Furthermore, in embodiments, the shell material 439 may comprise a second index of refraction n2.

[0256] Moreover, in embodiments, n2>nl+0.1.

[0257] Further, in embodiments, the first light transmissive material 420 may have a third index of refraction n3. Especially, one or more of the following may apply: (a) n3>nl+0.1 or (b) |n3-n2|>0.1. Further, in embodiments, |n3-n2| > |n3-nl| may apply.

[0258] Moreover, in embodiments, the first particulate material 431 may have a number averaged particle size selected from the range of 10-1000 nm (as measured with an electron microscope).2024PF80431

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[0260] Referring e.g. Fig. 2C, in embodiments, the first particulate material 431 may have a local concentration in the first light transmissive material 420 which over at least part of the first dimension DI increases with increasing distance (d) from the light in-coupling area 401.

[0261] Furthermore, in embodiments, the first luminescent material of the type M’xM2-2xAX6: Mn4+may be M’xM2-2xAi-mMnmX6. Furthermore, in embodiments, m<0.05.

[0262] Moreover, in embodiments, e.g. referring to Fig. 2D, the light guide arrangement 400 may comprise a second luminescent material 220 distributed over at least part of the first dimension DI. Moreover, in embodiments, the second luminescent material 220 may be configured to convert at least part of the device light 111 downstream from the light in-coupling area 401 into second luminescent material light 221. In embodiments, second luminescent material light 221 may have a second centroid wavelength (λc₂) selected from the range of 500-590 nm while (λdc + 30 nm) ≤ λc2 ≤ (λc₁ + 30 nm), such that during operation of the light generating device 110, second luminescent material light 221 may be generated and emanates from the light out-coupling area 402 (of the light guide arrangement 400) over at least part of the first dimension DI.

[0263] Furthermore, in embodiments, the light transmissive cladding 450 may comprise at least part of the second luminescent material 220, see e.g. embodiment VII of Fig. 2D. Note that the cladding 450 may be a multi-layer, allowing in embodiments a first layer comprising at least part of the first luminescent material 210 and a second layer comprising at least part of the second luminescent material 220. Here, references 457,458 refer to two layers of the multi-layer cladding. Alternatively or additionally, in embodiments, the coating layer 455 may comprise at least part of the second luminescent material 220. Note that the coating layer 455 may be a multi-layer, allowing in embodiments a first layer comprising at least part of the first luminescent material 210 and a second layer comprising at least part of the second luminescent material 220. Here, references 421,461 refer to two layers of the multi-layer coating layer.

[0264] Referring to Fig. 2e, the light guide arrangement 400 may e.g. comprise an elongated fiber, see embodiment I, or an (elongated) plate, see embodiment II. The second dimension D2 is in embodiment I e.g. a diagonal or thickness, and in embodiment II a height or thickness. Dimension D3 in embodiment II may be a width.

[0265] Referring to e.g. Fig. 1, light escaping from the light guide arrangement 400 may be indicated as arrangement light with reference 411. In the absence of other sources of light, the system light (see also below) may essentially consist of arrangement light 411.2024PF80431

[0266] 47

[0267] During operation of the light generating system, more especially during operation of the light generating device, light may escape from the light guide arrangement 400 via the light out-coupling area 402. This light emanates away from the light guide arrangement 400 and may also be indicated as arrangement light 411. The arrangement light 411 may comprise the first luminescent material light 211, optionally device light 111, and optionally second luminescent material light 221. In embodiments, especially when the arrangement light 411 comprises the first luminescent material light 211, device light 111, and second luminescent material light 221, this arrangement light 411 may be white light. For instance, the arrangement light 411 may in embodiments have a CCT of at least 1500 K, such as at least 1700 K, like at least 1800 K, and in specific embodiments at least 2000 K. Further, this arrangement light may in embodiments have a CCT of at maximum 20000 K, such as at maximum 12000 K, like at maximum 8000 K, and in specific embodiments at maximum 6500 K. Yet, the arrangement light 411 may in embodiments have a CRI of at least 60, such as at least 65, like in specific embodiments at least 70. Furthermore, in embodiments the CRI of the arrangement light 411 may be at least 75, such as at least about 80 or even higher. Hence, in specific embodiments the arrangement light 411 may comprise device light 111, first luminescent material light 211, and second luminescent material light 221, and may be white light having a correlated color temperature selected from the range of 2000-6500 K and a color rendering index of at least 70.

[0268] Hence, in embodiments, the light generating system 1000 may be configured to generate system light 1001. In further specific embodiments, in an operational mode of the light generating system 1000, the system light 1001 may have a spectral power distribution in the 380-780 nm wavelength range wherein xl% of the spectral power may be defined by the device light 111 ((also) escaping from the light guide arrangement 400 via the light out-coupling area 402 (of the light guide arrangement 400) (over at least part of the first dimension DI)), x2% of the spectral power may be defined by the first luminescent material light 211, and x3% of the spectral power may be defined by the second luminescent material light 221 as defined herein. In further embodiments, 2≤x1≤25, 30≤x2≤98, and 0≤x3≤58. In further embodiments, xl+x2+x3=100.

[0269] In further embodiments (not depicted), the light generating system 1000 may comprise at least two light generating devices 110. Furthermore, in embodiments, the light in-coupling area 401 may be configured in a light receiving relationship with the at least two light generating devices 110; the device light centroid wavelengths (λdc) of the device light2024PF80431

[0270] 48

[0271] 111 of the at least two light generating devices 110 may be selected from the wavelength range of 400-425 nm and / or from the wavelength range of 475-490 nm.

[0272] Referring to Figs. 1-2E, the first luminescent material 210 may be comprised by the light guide arrangement 400 over at least 80% of the first dimension DI.

[0273] Especially, the light generating system 1000 may further comprise an optical arrangement 505 configured in an optical path between the light generating device 110 and the light in-coupling area 401. In further embodiments, the optical arrangement 505 may be configured to facilitate incoupling of the device light 111 into the light guide arrangement 400.

[0274] Amongst others, herein in embodiments a light guide arrangement comprising KSiF phosphor particles for light conversion and blue light extraction is proposed. The KSiF phosphor particles may have the benefit of producing high-efficient high-quality red light. Thus, amongst others, a lighting arrangement configured to provide arrangement light and comprising (i) (first) light generating device arranged to emit blue light, such as in embodiments having a peak emission wavelength, λB, in a wavelength range of 400-500 nm, more especially 400-490 nm, (ii) an optical arrangement configured to receive the emitted blue light, and (iii) a light guide arrangement, wherein the optical arrangement is configured to in-couple at least part of the emitted blue light into the light guide arrangement, wherein the light guide arrangement comprises red phosphor particles dispersed in and along the length of the light guide arrangement, wherein the red phosphor particles are configured to at least partly convert at least part of the in-coupled blue light into red phosphor light such that part of the red phosphor light is coupled out of the light guide arrangement along the length of the light guide arrangement, wherein the red phosphor particles are configured to couple out part of the in-coupled blue light out of out of the light guide arrangement along the length of the light guide arrangement, wherein in specific embodiments the red phosphor light has a first centroid wavelength (λc₁), in a wavelength range of 610-650 nm, such as in embodiments 620-640 nm, and a full width at half maximum, FWHM, of < 40 nm, and wherein the red phosphor particles are of the type M’xM2-2xAX6 doped with tetraval ent manganese, wherein M’ comprises an alkaline earth cation, M comprises a monovalent cation, especially an alkaline cation, and x is in the range of 0-1, wherein A comprises a tetravalent cation, wherein X comprises a monovalent anion, at least comprising fluorine, is in embodiments herein suggested. In order to make white light, next to the outcoupled blue light and red phosphor light, the arrangement light may need green light. Therefore, in embodiments it is suggested that the light guide arrangement (also) comprises green2024PF80431

[0275] 49

[0276] phosphor particles dispersed in and along the length of the light guide arrangement. Because the red phosphor particles are of the KSiF class, they do substantially not absorb any green phosphor light thus further increasing the efficiency. In order to improve the blue light extraction of the KSiF phosphor particles it is in embodiments (further) suggested to implement or choose the following technical measures: (i) λB is in a wavelength range of 400-425 nm or 475-500 nm, such as 475-490 nm, because KSiF has a low absorption for these wavelength ranges; (ii) the KSiF phosphor particles comprises a coating having a higher refractive index than the KSiF phosphor particles because in contrast with most other phosphors, KSiF has a relatively low refractive index; (iii) increase the refractive index of the (polymer) matrix material of the light guide arrangement such that the refractive index difference with the KSiF particles is increased; (iv) the red phosphor particles may have a sub-micrometer diameter to match the blue light wavelength; (v) use a relative low Mn dopant concentration to lower the absorption level.

[0277] Fig. 3 schematically depicts an embodiment of a luminaire 2 comprising the light generating system 1000 as described above. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the light generating system 1000. Fig. 3 also schematically depicts an embodiment of lamp 1 comprising the light generating system 1000. Reference 3 indicates a projector device or projector system, which may be used to project images, such as at a wall, which may also comprise the light generating system 1000. Hence, Fig. 3 schematically depicts embodiments of a lighting device 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, a photochemical reactor, and an optical wireless communication device, comprising the light generating system 1000 as described herein. In embodiments, such lighting device may be a lamp 1, a luminaire 2, a projector device 3, a disinfection device, or an optical wireless communication device. Lighting device light escaping from the lighting device 1200 is indicated with reference 1201. Lighting device light 1201 may essentially consist of system light 1001, and may in specific embodiments thus be system light 1001. Reference 1300 refers to a space, such as a room. Reference 1305 refers to a floor and reference 1310 to a ceiling; reference 1307 refers to a wall. Fig. 3 also schematically depicts embodiments of an outdoor light, or stage light, or stadium light. Fig. 3 also schematically depicts a vehicle, like an automobile, but this may also be a truck, a motor cycle, etc. etc., with automotive lighting 4, e.g. headlights. These automotive lighting 4 may also comprise the lighting device 1200. Hence, the invention also provides a lighting device2024PF80431

[0278] 50

[0279] 1200 selected from the group of a lamp 1 and a luminaire 2 comprising the light generating system 1000 as described herein.

[0280] The term “plurality” refers to two or more. The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term “comprise” also includes embodiments wherein the term “comprises” means “consists of’. The term “and / or” especially relates to one or more of the items mentioned before and after “and / or”. For instance, a phrase “item 1 and / or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species". Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0281] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

[0282] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

[0283] The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may2024PF80431

[0284] 51

[0285] be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. In yet a further aspect, the invention (thus) provides a software product, which, when running on a computer is capable of bringing about (one or more embodiments of) the method as described herein. The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

[0286] The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and / or shown in the attached drawings. The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

[0287] The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

2024PF8043152CLAIMS:

1. A light generating system (1000) comprising a light generating device (110) and a light guide arrangement (400), wherein:the light generating device (110) is configured to generate device light (111) having a device light centroid wavelength (λdc) selected from the range of 380-490 nm; wherein the light generating device (110) comprises a semiconductor-based light generating device;the light guide arrangement (400) comprises a light in-coupling area (401), a first dimension (DI), a second dimension (D2), and a light out-coupling area (402) over at least part of the first dimension (DI); wherein the first dimension (DI) is a length, and wherein the second dimension (D2) is a circular equivalent diameter of a cross-sectional area defined perpendicular to the first dimension (DI); wherein D2 / D1≤0.1;the light in-coupling area (401) is configured in a light receiving relationship with the light generating device (110); wherein along at least part of the first dimension (DI) of the light guide arrangement (400) downstream of the light in-coupling area (401), the light guide arrangement (400) is at least partly transmissive for the device light (111) coupled into the light guide arrangement (400) via the light in-coupling area (401);the light guide arrangement (400) comprises a first luminescent material (210); wherein the first luminescent material (210) comprises a luminescent material of the type M’xM2-2xAX6: Mn4+, wherein M’ comprises an alkaline earth cation, M comprises a monovalent cation, and x is in the range of 0-1, wherein A comprises a tetravalent cation, comprising one or more of silicon, titanium, and germanium, wherein X comprises a monovalent anion, at least comprising fluorine; wherein the first luminescent material (210) is configured to convert at least part of the device light (111) downstream from the light incoupling area (401) into first luminescent material light (211), wherein the first luminescent material light (211) has a first centroid wavelength (λc₁) selected from the range of 610-650 nm, wherein the first luminescent material light (211) comprises at least one emission band having a first full width at half maximum FWHM₁ of ≤ 45 nm;the light guide arrangement (400) comprises a first particulate material (431) embedded in a first light transmissive material (420) over at least part of the first dimension2024PF8043153(DI); wherein the first particulate material (431) comprises at least part of the first luminescent material (210); wherein the first particulate material (431) has a difference in refractive index with respect to the first light transmissive material (420) of at least 0.1;the first luminescent material (210) is distributed over at least part of the first dimension (DI) such that during operation of the light generating device (110), first luminescent material light (211) is generated and emanates from the light out-coupling area (402) of the light guide arrangement (400) over at least part of the first dimension (DI);the light guide arrangement (400) comprises a second luminescent material (220), wherein the second luminescent material (220) is configured to convert at least part of the device light (111) downstream from the light in-coupling area (401) into second luminescent material light (221), wherein the second luminescent material light (221) has a second centroid wavelength (λc2) selected from the range of 500-590 nm;the second luminescent material (220) is distributed over at least part of the first dimension (DI) such that during operation of the light generating device (110), second luminescent material light (221) is generated and emanates from the light out-coupling area (402) over at least part of the first dimension (DI);the light generating system (1000) is configured to generate system light (1001) comprising device light (111), first luminescent material light (211), and second luminescent material light (221) and wherein in an operational mode of the light generating system (1000), the system light (1001) has a spectral power distribution in the 380-780 nm wavelength range wherein: xl% of the spectral power is defined by the device light (111), x2% of the spectral power is defined by the first luminescent material light (211), and x3% of the spectral power is defined by the second luminescent material light (221), wherein 2<xl<25, 20<x2<98, and 0<x3<58, and wherein xl+x2+x3=100; andthe system light is white light having a correlated color temperature selected from the range of 2000-6500 K and a color rendering index of at least 70.

2. The light generating system (1000) according to claim 1, wherein the light generating system (1000) is configured such that during operation of the light generating device (110) at least part of the device light (111) propagates through the light guide arrangement (400) over at least part of the first dimension (DI) while being totally internally reflected multiple times and subsequently coupled out from the light guide arrangement (400) and emanates from the light out-coupling area (402) of the light guide arrangement (400) over at least part of the first dimension (DI).2024PF80431543. The light generating system (1000) according to any one of the preceding claims, wherein the light guide arrangement (400) comprises a body (410), wherein the body (410) comprises a light transmissive core (415); wherein the light transmissive core (415) comprises a light transmissive core material (417); and wherein the body (410) further comprises a light transmissive cladding (450) at least partially enclosing the light transmissive core (415) over at least part of the first dimension (DI); the light transmissive cladding (450) comprises the first light transmissive material (420) and at least part of the first particulate material (431).

4. The light generating system (1000) according to claim 3, wherein the light guide arrangement (400) further comprises a coating layer (455) at least partially enclosing the body (410) over at least part of the first dimension (DI); wherein the coating layer (455) comprises a light transmissive coating material (458).

5. The light generating system (1000) according to any one of the preceding claims, wherein the first luminescent material (210) has a first index of refraction nl; wherein the first particulate material (431) comprises particles (432), wherein the particles comprise a particle core (433), comprising at least part of the first luminescent material (210), and a particle shell (438) at least partially enclosing the particle core (433), wherein the particle shell (438) comprises shell material (439); wherein the shell material (439) comprises a second index of refraction n2; and wherein n2>nl+0.1.

6. The light generating system (1000) according to any one of the preceding claims, wherein the first light transmissive material (420) has a third index of refraction n3, wherein one or more of the following applies: (a) n3>nl+0.1 or (b) I n3-n2 I >0.1, wherein nl and n2 are as defined in claim 5.

7. The light generating system (1000) according to any one of the preceding claims, wherein the first particulate material (431) has a number averaged particle size selected from the range of 10-1000 nm.

8. The light generating system (1000) according to any one of the preceding claims, wherein the first particulate material (431) has a local concentration in the first light2024PF8043155transmissive material (420) which over at least part of the first dimension (DI) increases with increasing distance (d) from the light in-coupling area (401).

9. The light generating system (1000) according to any one of the preceding claims, wherein the first luminescent material of the type M M2-2xAXe: Mn4+is M’XM2-2XAI.mMnmX6, wherein m<0.05.

10. The light generating system (1000) according to any one of the preceding claims, wherein (λdc + 30 nm) ≤ λc2 ≤ (λc₁ + 30 nm).

11. The light generating system (1000) according to claim 10, further comprising the light transmissive cladding (450) according to claim 3, wherein the light transmissive cladding (450) comprises at least part of the second luminescent material (220).

12. The light generating system (1000) according to any one of claims 4-10, wherein the coating layer (455) comprises at least part of the second luminescent material (220).

13. The light generating system (1000) according to any one of claims, wherein 30<x2<98 and 5<x3<58.

14. The light generating system (1000) according to any one of claims, wherein the light generating system (1000) comprises at least two light generating devices (110), wherein the light in-coupling area (401) is configured in a light receiving relationship with the at least two light generating devices (110); the device light centroid wavelengths (λdc) of the device light (111) of the at least two light generating devices (110) are selected from the wavelength range of 400-425 nm and / or from the wavelength range of 475-490 nm; the first luminescent material (210) is comprised by the light guide arrangement (400) over at least 80% of the first dimension (DI); the light generating system (1000) further comprise an optical arrangement (505) configured in an optical path between the light generating device (110) and the light in-coupling area (401); and the optical arrangement (505) is configured to facilitate incoupling of the device light (111) into the light guide arrangement (400).2024PF804315615. A lighting device (1200) selected from the group of a lamp (1) and a luminaire (2) comprising the light generating system (1000) according to any one of the preceding claims.

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