Phosphor composition and light source for SWIR spectroscopy

Abstract

A first luminescent material having a peak emission wavelength in the range of 1600-1900 nm includes a garnet phosphor co-doped with Cr < 3 + > and Tm < 3 + > having the general formula: (Gd < 3-u-y > TmyREu) [Ga2-a-b-d-eLuaCrbScdAle] {Ga3-cAlc} O12, where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0 < = u < = 2, 0lt; y < = 1.5, 0 < = a < = 1, 0lt; b < = 0.3, 0 < = c < = 3, 0 < = d < = 0.5, and 0 < = e < = 1.8. A second luminescent material having a peak emission wavelength in the range of 1400-1600 nm includes a garnet phosphor co-doped with Cr < 3 + > and Ni < 2 + > having the general formula: (Gd < 3-u > REu) [Ga2-a-b-d-eNiaCrbLdAle] {Ga3-cAlc} O12, where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0 < = u < = 2, 0lt; a is less than or equal to 0.1, 0lt; b < = 0.3, 0 < = c < = 3, 0lt; d < = 0.15, 0 < = e < = 2. A light source comprises first and second luminescent materials and one or more semiconductor light emitting diodes arranged to excite light emission from the luminescent materials to provide short wavelength infrared emission in the range of 1300-2000 nm.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 356,131, filed on June 28, 2022, which is incorporated herein by reference in its entirety. This application is related to U.S. Provisional Patent Application No. 63 / 235,523, filed on August 20, 2021, which is also incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to phosphor compositions for use in the short wave infrared spectrum (SWIR) in the spectral range of 1300-2200 nm, and to devices employing such phosphor compositions. Background Art

[0004] Semiconductor light emitting diodes and laser diodes (collectively referred to herein as "LEDs") are among the most efficient light sources currently available. The emission spectrum of an LED typically exhibits a single narrow peak at a wavelength determined by the structure of the device and the composition of the semiconductor material from which it is constructed. By appropriately selecting the device structure and material system, an LED can be designed to operate at ultraviolet, visible, or infrared wavelengths.

[0005] The LED may be combined with one or more wavelength converting materials (generally referred to herein as "phosphors") that absorb light emitted by the LED and in response emit light of a longer wavelength. For such phosphor-converted LEDs ("pcLEDs"), the fraction of light emitted by the LED that is absorbed by the phosphor depends on the amount of phosphor material in the optical path of the light emitted by the LED, for example, on the concentration of the phosphor material in a phosphor layer disposed on or around the LED and the thickness of the layer.

[0006] Phosphor-converted LEDs can be designed so that all light emitted by the LED is absorbed by one or more phosphors, in which case the emission from the pcLED is entirely from the phosphors. In this case, for example, the phosphors can be selected to emit light in a spectral region that is not efficiently generated directly by the LED.

[0007] Alternatively, the pcLED can be designed so that only a portion of the light emitted by the LED is absorbed by the phosphor, in which case the emission from the pcLED is a mixture of the light emitted by the LED and the light emitted by the phosphor. By appropriately selecting the LED, phosphor, and phosphor components, such a pcLED can be designed to emit light having, for example, a desired color temperature and desired color rendering properties. Summary of the invention

[0008] In one aspect, a luminescent material is provided that emits light having an emission wavelength in the range of 1600 - 2200 nm. The luminescent material includes a structurally disordered garnet material doped with at least one sensitizer ion and at least one rare earth emitter ion. The structurally disordered garnet material can include a composition derived from structurally ordered gadolinium gallium garnet (Gd3)[Ga2]{Ga3}O 12 (which has three Gd atoms in 8 - fold coordination, two Ga atoms in 6 - fold coordination, and three Ga atoms in 4 - fold coordination). The structurally disordered garnet material can include atoms that can occupy more than one lattice site. Gadolinium can be partially replaced by at least one rare earth element selected from the group consisting of at least one of Tm, Ho, La, Y, Yb, Nd, Er, and Ce. The rare earth emitter ions can be a combination of Tm and Ho. The rare earth emitter ions can be Tm. The SWIR phosphor can include (Gd 3-u-v-x-y-z Lu x Tm y Ho z Sc v RE u )[Sc 2-a-b-d-e Lu a Cr b Ga d Al e {Ga 3-c Al c}O 12 , where RE = La, Y, Yb, Nd, Er, Ce and 0 ≤ u ≤ 2, 0 < v ≤ 1, 0 < x ≤ 1, 0 < y ≤ 0.5, 0 ≤ z ≤ 0.05, 0 < a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 1.8, 0 ≤ e ≤ 1.8. The SWIR phosphor can include (Gd,Lu)3(Sc,Lu)2(Ga,Al)3 crystallized in a structurally disordered cubic garnet structure type. The SWIR phosphor can include Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.0 4O 12 、Gd 2.59 Tm 0.24 Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12 、Gd2Ho 0.013 Tm 0.2 Sc 0.67 Lu 0.24Ga 1.6 Al 3.2 Cr 0.08 O 12 and Gd 2.67 Ho 0.01 Tm 0.17 Sc 1.8 Lu 0.3 Ga2AlCr 0.05 O 12 at least one of

[0009] In another aspect, a wavelength conversion structure is provided, the wavelength conversion structure comprising a SWIR phosphor having an emission wavelength in the range of 1600 - 2200 nm, the SWIR phosphor comprising a structurally disordered garnet material, a sensitizer ion, and at least one rare earth emitter ion. The structurally disordered garnet material may comprise a composition derived from structurally ordered gadolinium gallium garnet (Gd3)[Ga2]{Ga3}O 12 (which has Gd atoms with 8-fold coordination, Ga atoms with 6-fold coordination, and Ga atoms with 4-fold coordination). The structurally disordered garnet material may comprise atoms that can occupy more than one lattice site. Gadolinium may be partially replaced by at least one rare earth element selected from the group consisting of Tm, Ho, La, Y, Yb, Nd, Er, and Ce. The rare earth emitter element may be a combination of Tm and Ho. The rare earth emitter element may be Tm. The SWIR phosphor may comprise (Gd 3-u-v-x-y- z Lu x Tm y Ho z Sc v RE u )[Sc 2-a-b-d-e Lu a Cr b Ga d Al e {Ga 3-c Al c}O 12 , where RE = La, Y, Yb, Nd, Er, Ce and 0 ≤ u ≤ 2, 0 < v ≤ 1, 0 < x ≤ 1, 0 < y ≤ 0.5, 0 ≤ z ≤ 0.05, 0 < a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 1.8, 0 ≤ e ≤ 1.8. The undoped host lattice of the SWIR phosphor may comprise (Gd, Lu, Sc)3[Sc, Lu, Ga, Al])2{Ga, Al}3O 12 crystallized in a structurally disordered cubic garnet structure type. The SWIR phosphor may comprise Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12 , Gd 2.59 Tm 0.24 Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12 ,Gd2 0.013 Tm 0.2 Sc 0.67 Lu 0.24 Ga 1.6 Al 3.2 Cr 0.08 O 12 and Gd 2.67 Ho 0.01 Tm 0.17 Sc 1.8 Lu 0.3 Ga2AlCr 0.05 O 12 At least one of .

[0010] The wavelength conversion structure may further include an additional IR phosphor having an emission in the wavelength range of 1100-1700 nm. The additional IR phosphor may include a doped Ni 2+ Or Ni 2+ and Cr 3+ One or more of the spinel, perovskite and / or garnet IR phosphors of the composition (Gd)3[Sc,Ga,Ni,Zr,Cr]2{Ga,Al}3O 12 Ni-doped 2+ and Cr 3+ Garnet phosphors such as Gd3Ga 3.7 SCa 0.18 Ni 0.02 Zr 0.02 1Cr 0.1 O 12 and Gd3Ga 4.7 Al 0.18 Ni 0.02 Zr 0.021 Cr 0.1 O 12 .

[0011] In another aspect, an IR emitting device is provided, the IR emitting device comprising: a wavelength conversion structure, the wavelength conversion structure comprising a SWIR phosphor, the SWIR phosphor having an emission in a wavelength range of 1600-2200 nm and a continuous emission spectrum in a spectral width of at least 500 nm; and a light source configured to emit primary light into the wavelength conversion structure. The SWIR phosphor may include (Gd 3-u-v-x-y-z Lu x Tm y Ho z Sc v RE u )[Sc 2-a-b-d-e Lu a Cr b Ga d Al e ]{Ga 3-c Al c} 12 , where RE = La, Y, Yb, Nd, Er, Ce and 0≤u≤2,0 <v≤1、0<x≤1、0<y≤0.5、0≤z≤0.05、0<a≤1、0<b≤0.3、0≤c≤3、0<d≤1.8、0≤e≤1.8。

[0012] In another aspect, a luminescent material having a peak emission wavelength in the range of 1600-1900 nm comprises Cr having the general formula 3+ and Tm 3+ Co-doped garnet phosphor: (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d- e Lu a Cr b Sc d Al e ]{Ga 3-c Al c} 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0≤u≤2,0 <y≤1.5、0≤a≤1、0<b≤0.3、0≤c≤3、0≤d≤0.5、0≤e≤1.8。

[0013] In another aspect, a luminescent material having a peak emission wavelength in the range of 1400-1600 nm comprises Cr having the general formula 3+ and Ni 2+ Co-doped garnet phosphor: (Gd 3-u RE u )[Ga 2-a-b-d-eNi a Cr b L d Al e {Ga 3-c Al c}O 12 , wherein RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0 ≤ u ≤ 2, 0 < a ≤ 0.1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 0.15, 0 ≤ e ≤ 2.

[0014] In another aspect, a wavelength conversion structure is provided, the wavelength conversion structure comprising: a SWIR phosphor having the general formula (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Sc d Al e {Ga 3-c Al c}O 12 , wherein RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0 ≤ u ≤ 2, 0 < y ≤ 1.5, 0 ≤ a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 1.8; and / or a SWIR phosphor having the general formula (Gd 3-u RE u )[Ga 2-a-b-d-e Ni a Cr b L d Al e {Ga 3-c Al c}O 12 , wherein RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0 ≤ u ≤ 2, 0 < a ≤ 0.1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 0.15, 0 ≤ e ≤ 2.

[0015] In another aspect, an IR emitting device is provided, the IR emitting device comprising a wavelength conversion structure and a light source, the light source being configured to emit primary light into the wavelength conversion structure, the wavelength conversion structure comprising: a SWIR phosphor having the general formula (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Scd Al e {Ga 3-c Al c}O 12 SWIR phosphor of, where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0 ≤ u ≤ 2, 0 < y ≤ 1.5, 0 ≤ a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 1.8; and having the general formula (Gd 3-u RE u )[Ga 2-a-b-d-e Ni a Cr b L d Al e {Ga 3-c Al c}O 12 SWIR phosphor of, where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0 ≤ u ≤ 2, 0 < a ≤ 0.1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 0.15, 0 ≤ e ≤ 2.

[0016] In another aspect, an ultra - broadband pcLED light source for covering the SWIR spectrum in the 1300 - 2000 nm spectral range shows an intensity variation < 5% or even < 3% for an LED board temperature range of 0 - 100 °C and wavelength ranges centered at 1650, 1720, and 1820 nm. The light source can be applied to a wide range of SWIR spectral applications and is particularly suitable for the quantitative measurement of skin hydration and sebum (skin surface lipids) levels. The light source includes a primary light source that emits blue (e.g., InGaN LED), two garnet - based host lattice phosphors, a Cr 3+ sensitizer and a Ni 2+ or Tm 3+ activator ion, and an optical adhesive material (e.g., silicone - based), which is preferably a polydimethylsiloxane - type polymer. Due to the highly constant light output at varying ambient temperatures, the light source is particularly suitable for integration into wearable devices or portable devices (such as smart phones and smart watches), where sensor devices need to operate precisely over a wide temperature range. The two phosphors can be, for example: having the general formula (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Sc d Al e {Ga 3-c Alc}O 12 SWIR phosphor, where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0 ≤ u ≤ 2, 0 < y ≤ 1.5, 0 ≤ a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 1.8; and having the general formula (Gd 3-u RE u )[Ga 2-a-b-d-e Ni a Cr b L d Al e {Ga 3- c Al c}O 12 SWIR phosphor, where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0 ≤ u ≤ 2, 0 < a ≤ 0.1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 0.15, 0 ≤ e ≤ 2.

[0017] In another aspect, a spectrometer includes: any suitable combination of the phosphor compositions or wavelength conversion structures outlined above; a light source configured to excite the SWIR emission from the phosphor or wavelength conversion structure; and a light detector configured to detect such emission when reflected from or transmitted through a sample, such as for example human skin.

[0018] In another aspect, a wearable device or a handheld device such as a smart phone or a smart watch for example includes a spectrometer as outlined above. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Shows an embodiment of a wavelength conversion structure as part of an infrared light emitting device.

[0020] Figure 2 Shows another embodiment of a wavelength conversion structure as part of an infrared light emitting device.

[0021] Figure 3 Is a cross-sectional view of an example of an LED.

[0022] Figure 4 Is a cross-sectional view of an IR emitting device having a wavelength conversion structure in direct contact with an LED.

[0023] Figure 5 Is a cross-sectional view of an IR emitting device having a wavelength conversion structure adjacent to an LED.

[0024] Figure 6is a cross-sectional view of an IR emitting device having a wavelength conversion structure spaced apart from an LED.

[0025] Fig. 7A An example IR spectrometer including an IR emitting device is shown.

[0026] Figure 7B Another example IR spectrometer including an IR emitting device is shown.

[0027] Fig. 8A and Figure 8B Schematic cross-sectional and top views of a SWIR pcLED array are shown, respectively.

[0028] Fig. 9A shows a schematic top view of an electronic board on which a pcLED array may be mounted, and Fig. 9B Similarly, the installation Fig. 9A SWIR pcLED array on an electronics board.

[0029] Fig. 10A A schematic cross-sectional view of a SWIR pcLED array arranged relative to a waveguide and projection lens is shown. Fig. 10B shows the difference between the case without waveguide and Fig. 10A The arrangement is similar to the arrangement of .

[0030] Fig.11 An example smartphone system is schematically illustrated.

[0031] Fig.12 An example display (e.g., AR / VR / MR) system including an adaptive lighting system is schematically illustrated.

[0032] Fig.13 It shows that Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12 X-ray powder pattern of SWIR phosphor (copper radiation).

[0033] Fig.14 It shows that Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12Scanning electron microscope (SEM) image of the SWIR phosphor.

[0034] Fig.15 It shows that Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12 Power reflectance spectra of SWIR phosphors in the visible spectral range.

[0035] Fig.16 Shown including Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12 Normalized shortwave infrared emission spectrum of the SWIR pcLED of the SWIR phosphor.

[0036] Fig.17 It shows that Gd 2.59 Tm 0.24 Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12 X-ray powder pattern of SWIR phosphor (copper radiation).

[0037] Fig.18 Shown including Gd 2.59 Tm 0.24 Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12 Normalized shortwave infrared emission spectrum of the SWIRpcLED of the SWIR phosphor.

[0038] Fig.19 A scanning electron micrograph of the sintered SWIR phosphor ceramic of Example 5 is shown.

[0039] Fig. 20 The light transmittance of the coated ceramic plate of Example 6 is shown.

[0040] Fig.21 is the SWIR emission spectrum of the phosphor-converted LED of Example 7.

[0041] Fig.22A The IR spectroscopy test setup is schematically shown. Fig. 22B Schematic diagram of a test sample Fig.22A IR spectrum test device.

[0042] Fig.23 is the FT-IR spectrum of the polystyrene test sample.

[0043] Fig.24 is the spectral power distribution of the phosphor of Example 8 in the SWIR wavelength range.

[0044] Fig.25 The emission spectrum of the pcLED of Example 11 is shown.

[0045] Fig.26 The variation in emission power of the pcLED of Example 11 as a function of the ambient temperature is shown.

[0046] Fig. 27 The emission spectrum of the pcLED of Example 12 is shown.

[0047] Fig.28 The variation in emission power of the pcLED of Example 12 as a function of the ambient temperature is shown.

[0048] Fig.29 The emission spectrum of the pcLED of Example 13 is shown.

[0049] Fig.30 The variation in emission power of the pcLED of Example 13 as a function of the ambient temperature is shown. DETAILED DESCRIPTION

[0050] The following detailed description should be read with reference to the accompanying drawings, wherein the same reference numerals refer to similar elements throughout the different figures. The drawings, which are not necessarily to scale, depict selective embodiments and are not intended to limit the scope of the invention. The detailed description illustrates the principles of the invention by way of example, not by way of limitation.

[0051] The present specification discloses phosphors that can emit infrared ("IR") radiation in the short wavelength infrared radiation range ("SWIR"), and more specifically, SWIR phosphors that can emit infrared radiation with a peak wavelength in the range of 1600nm to 2200nm. In particular, some of the SWIR phosphors disclosed herein are capable of providing a continuous emission spectrum in the range of 1600nm to 2200nm, without emission gaps, while maintaining high conversion efficiency. For example, the SWIR phosphors disclosed herein can provide a continuous emission spectrum over a spectral width of at least 500nm and have a minimum spectral power in the emission range of 1600nm to 2200nm, and the minimum spectral power is at least 20% of the median spectral power in the range.

[0052] The present specification also discloses SWIR phosphors and phosphor combinations that can emit infrared radiation in the range of 1300nm to 2000nm with an intensity variation of <5% or even <3% over the temperature range of 0-100°C and a wavelength range centered around 1650, 1720 and 1820nm.

[0053] The SWIR phosphors disclosed herein can be excited by light having a wavelength in the blue spectral range. Broadband SWIR phosphor materials can efficiently convert shorter wavelength blue light into broadband emission having longer SWIR wavelengths. For economy of language, infrared radiation may be referred to herein as "infrared light," "IR light," or "light."

[0054] The specification also discloses a light source including the SWIR phosphor disclosed herein. Such a light source may include a primary light source (such as an LED) and a wavelength conversion structure including the SWIR disclosed herein to form, for example, a SWIRpcLED. The use of a broadband SWIR phosphor in such a light source may extend the wavelength emitted by the light source to up to 2200 nm while providing a continuous spectral power distribution over a wide wavelength range and maintaining high conversion efficiency.

[0055] The wavelength conversion structure in the light source may further include additional phosphors. The additional phosphors may include, for example, other SWIR phosphors that emit wavelengths in other parts of the infrared wavelength range, such as in the 1000-1700 nm spectral range. The additional phosphors may also allow for more efficient excitation of the SWIR phosphors.

[0056] The present specification also discloses a wavelength conversion structure and a SWIR light emitting device including such a broadband SWIR phosphor.The wavelength conversion structure and the light emitting device having the broadband SWIR phosphor may further include additional phosphors.

[0057] The present specification also discloses the use of a light emitting device with a broadband SWIR phosphor in a spectrometer device for IR absorption and reflection spectroscopy applications, wherein a light emitting device with a SWIR phosphor (such as a SWIRpcLED as disclosed herein) is used to replace a traditional incandescent light source (such as a tungsten filament lamp). Currently, tungsten filament light sources with a CCT in the range of 2300K are used to cover the spectral range required for SWIR spectrometer systems (e.g., 1000nm to 3000μm). However, tungsten filament light sources lack mechanical strength, fast modulation capabilities to improve spectrometer sensitivity, and compactness, which is necessary, for example, for integrating IR absorption spectroscopy into small handheld devices and wearable devices or smart phones. The SWIR phosphors disclosed herein combine a broadened emission band as preferred for spectroscopy applications with a high conversion efficiency, which means that they require less power and can be used in miniaturized devices (such as wearable devices).

[0058] The disclosed light sources are highly efficient and allow for further miniaturization and cost reduction of spectrometer systems, sensors, and hyperspectral or multispectral imaging systems covering the 1600-2200 nm wavelength range as well as the 1000 nm to 2200 nm range.

[0059] Certain applications for such SWIR pcLEDs can also be found in the medical field, i.e., in sensors and in endoscopic hyperspectral or multispectral imaging of tissues where efficient, high-intensity light sources are particularly needed (see, e.g., Hayashi et al., A broadband LED source in visible to shortwave-infrared wavelengths for spectral tumor diagnostics, Appl. Phys. Lett. 110, 233701 (2017)). Other uses include, for example: detecting and sensing polymers that differ in their macromolecular composition, which can be easily identified by their unique IR absorption patterns; and also hyperspectral imaging applications.

[0060] For example, such a SWIR pcLED can be used for the quantitative measurement of skin hydration and sebum (skin surface lipids) levels. "Quantitative and simultaneous non-invasive measurement of skin hydration and sebum levels" by Ezerskaia et al., Biomedical Optics Express 2311 (2016) describes a method for determining skin hydration and sebum levels by means of SWIR spectroscopy and a laser light source system. For sebum sensing, a wavelength of approximately 1720 nm has been selected because the ratio of the lipid absorption coefficient to the water absorption coefficient is high (see Figure 1 in that reference), and it is less affected by other skin components. Additionally, for differential detection, wavelengths of approximately 1750 nm and 1770 nm have been selected. To form a light source laser with corresponding emission wavelengths, beam shaping optics and mirrors have been combined. The wavelengths around 1750 nm and 1770 nm represent ranges of approximately equal and low ratios of the sebum absorption coefficient to the water absorption coefficient, and have been selected based on the availability of suitable light sources.

[0061] To utilize this method at the point of care diagnosis or even in consumer products such as smart phones, a light source that emits in a wider range such as 1400 - 2000 μm is required, which emits with high temperature stability, especially in the wavelength range around 1720 nm. Such a light source including a SWIR phosphor as disclosed herein can be combined with an IR sensor element, such as an InGaAs photodiode or a PbS photosensitive resistor equipped with a filtering element, to make the sensor sensitive to a specific wavelength range. A light source suitable for this application includes a wavelength conversion structure and a light source configured to emit primary light into the wavelength conversion structure, the wavelength conversion structure including: a SWIR phosphor having the general formula (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Sc d Al e {Ga 3-c Al c}O 12 where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0 ≤ u ≤ 2, 0 < y ≤ 1.5, 0 ≤ a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 1.8; and a SWIR phosphor having the general formula (Gd 3-u RE u )[Ga 2-a-b-d-eNi a Cr b L d Al e ]{Ga 3-c Al c} 12 SWIR phosphors, wherein RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0 ≤ u ≤ 2, 0 <a≤0.1、0<b≤0.3、0≤c≤3、0<d≤0.15、0≤e≤2。

[0062] SWIR phosphor composition

[0063] The SWIR phosphor compounds disclosed herein include: (i) a (optionally structurally disordered) garnet host lattice material; (ii) at least one sensitizer ion; and (iii) at least one (eg, rare earth) emitter ion.

[0064] The structurally disordered garnet host lattice material is a garnet lattice with multiple chemically different doping sites. The disordered structure of the garnet lattice provides a multi-element host that broadens the emission band of the rare earth emitter ion dopant, thereby producing a broadband emission spectrum, and maintaining sufficient crystal structure to provide high conversion efficiency. As used herein, the term "structural disorder" refers to a material with an ordered average structure or long-range translational periodicity, which can be characterized, for example, by X-ray diffraction experiments. However, different crystallographic lattice sites are occupied by chemically different atomic species in a disordered but more statistical manner, resulting in a variety of slightly different chemical alternative lattice sites for sensitizers and emitter ions, and thus resulting in non-uniformly broadened spectral features, which are highly desired for the application of SWIR phosphors. The host lattice has a considerable influence on the optical properties of the dopant, and changes in its chemical environment cause changes in the crystal field at the dopant site, which can lead to non-uniform (and therefore broader) emission. Therefore, the use of a structurally disordered garnet host lattice as disclosed herein can help provide a more continuous emission spectrum. At the same time, using a too disordered host lattice may lead to a decrease in conversion efficiency due to, for example, a high concentration of optically active lattice defects. 3+ The broadening effect required for sensitized converters is achieved by adding relatively large amounts of elements such as Lu, Sc and Al to the garnet material.

[0065] The structurally disordered garnet host lattice component used herein can be derived from a gadolinium gallium garnet Gd3Ga2Ga3O having three 8-fold coordinated Gd atoms, two 6-fold coordinated Ga atoms, and three 4-fold coordinated Ga atoms. 12. Example host lattice components can include atoms that can occupy more than one lattice site, such as, for example, Lu and Sc (which have possible 8-fold and 6-fold coordination) and Al (which has possible 6-fold and 4-fold coordination). This disorder is caused by the statistical distribution of one element on the various lattice sites of the garnet structure. For example, lutetium or scandium can occupy 8-fold and 6-fold coordinated lattice sites, while gallium and aluminum can occupy 6-fold and 4-fold coordinated lattice sites at concentrations exceeding trace or defect levels (>1 atom%). If according to (Gd,Lu,Sc,Tm)3[Sc,Lu,Ga,Al,Cr]2{Ga,Al}3O 12 , the host lattice is further doped with, for example, chromium (III) and thulium, these dopants then occupy multiple chemically different 6-fold or 8-fold coordination sites, which are caused by the statistical distribution of the host lattice elements occupied by multiple sites, respectively. Therefore, this disorder may lead to, for example, the desired broadening of the absorption and emission transitions of chromium (III) and thulium, respectively. The mixed occupation of these sites leads to multiple different emission sites in terms of oxygen ligand charge and distance and / or coordination geometry. This structurally disordered structure leads to a broadening of the emission bands of the composition and thereby leads to a more uniform spectral power distribution within the desired range.

[0066] An example of a structurally disordered garnet host lattice is (Gd,Lu,Sc)3(Sc,Lu,Ga)2(Ga,Al)3O crystallized in the cubic garnet structure type. 12 In this example, the composition of the binary oxide forming the garnet phase is selected so that lutetium is bound to both 8-fold and 6-fold coordinated cation sites. Alternatively, another example of a structurally disordered host lattice is (Gd,Lu,Sc)3Sc2(Ga,Al)3O 12 , which also crystallizes in the cubic garnet structure type and has Sc atoms in both 8-fold and 6-fold coordinated sites.

[0067] The SWIR phosphor disclosed herein is doped with at least one sensitizer ion. The sensitizer ion effectively absorbs blue or red pump light (e.g., from an LED) and transfers the absorbed energy to a rare earth emitter ion, which ultimately emits in a desired spectral range. In order to effectively absorb excitation light from a primary LED light source in the blue or red spectral range, the host material can be doped with, for example, Cr(III) as a sensitizer ion on a 6-fold coordinated site.

[0068] The SWIR phosphors disclosed herein can be doped with at least one rare-earth emitter ion, or a combination of rare-earth emitter ions, or another emitter ion, which provides emission in the desired spectral range. For example, a SWIR phosphor that provides emission in the wavelength range of 1600 - 2200 nm can have an 8 - coordinate site doped with Tm(III) and Ho(III) or only doped with Tm(III). In addition, the host lattice can be doped with Er(III) to extend the emission range to ~1500 nm. By replacing additional portions of Gd with La, Y, Yb, Nd, or Ce, the excitation and emission properties can be further adjusted.

[0069] The SWIR phosphors disclosed herein can have a composition that includes phosphors from the garnet material class, which have the following composition: (Gd 3-u-v-x-y-z Lu x Tm y Ho z Sc v RE u )[Sc 2-a-b-d-e Lu a Cr b Ga d Al e {Ga 3-c Al c}O 12 , where RE = La, Y, Yb, Nd, Er, Ce and 0 ≤ u ≤ 2, 0 < v ≤ 1, 0 < x ≤ 1, 0 < y ≤ 0.5, 0 ≤ z ≤ 0.05, 0 < a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 1.8, 0 ≤ e ≤ 1.8. Examples of SWIR phosphors having a composition of this garnet material class are described in more detail below and include Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12 、Gd 2.59 Tm 0.2 4Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12 、Gd2Ho 0.013 Tm 0.2 Sc 0.67 Lu 0.24 Ga 1.6 Al 3.2 Cr 0.08 O12 , and Gd 2.67 Ho 0.01 Tm 0.17 Sc 1.8 Lu 0.3 Ga2AlCr 0.05 O 12 .

[0070] The SWIR phosphors disclosed herein can be or include Cr 3+ and Tm 3+ codoped garnet phosphors having the following general formula: (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Sc d Al e {Ga 3-c Al c}O 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0 ≤ u ≤ 2, 0 < y ≤ 1.5, 0 ≤ a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 1.8. In this phosphor family, Cr 3+ is the sensitizer ion and Tm 3+ is the emitter ion.

[0071] The SWIR phosphors disclosed herein can be or include Cr 3+ and Ni 2+ codoped garnet phosphors having the following general formula: (Gd 3-u RE u )[Ga 2-a-b-d-e Ni a Cr b L d Al e {Ga 3-c Al c}O 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0 ≤ u ≤ 2, 0 < a ≤ 0.1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 0.15, 0 ≤ e ≤ 2. In this phosphor family, Cr 3+ is the sensitizer ion and Ni 2+ is the emitter ion.

[0072] In the phosphor compositions disclosed above, other elements with different charges can optionally be integrated into the garnet host lattice as couples on different lattice sites. For example, small or trace amounts of (Ca 2+ )+[Zr 4+ ] or (Mg 2+ )2+[Nb 5+ ] or (Ca 2+ )+[Si 4+ ] without significantly compromising the desired properties, where brackets indicate different garnet lattice sites, derived from gadolinium gallium garnet (Gd3)[Ga2]{Ga3}O 12 , with 8-fold coordinated Gd atoms, 6-fold coordinated Ga atoms, and 4-fold coordinated Ga atoms.

[0073] In order to improve the crystal quality of the SWIR phosphor, a flux (such as a fluoride) can be applied during the manufacture of the SWIR phosphor composition (e.g., powder phosphor processing), which can cause elements from such a flux to be incorporated into the SWIR composition. An example of a flux system for a SWIR phosphor composition is gadolinium fluoride. The application of a fluoride flux can cause some fluoride ions to be incorporated into the final SWIR phosphor composition without compromising its desired properties. Alternative flux systems can be, for example, barium fluoride (BaF2) or AlF3 hydrates, or borates, or chlorides. Other exemplary flux systems that can be applied include, for example, silicon oxide, which can be used to manufacture a ceramic phosphor wavelength conversion structure (described in more detail below), which can be characterized as a polycrystalline sintered luminescent converter element that includes the SWIR phosphor disclosed herein as at least part of a polycrystalline matrix. The silica flux may be added as fine silica powder or, for example, in the form of a precursor such as an alkoxide (e.g., tetraethyl orthosilicate) which is hydrolyzed during processing. The remainder of the polycrystalline matrix may be, for example, an oxide such as alumina (Al2O3) or a mixed oxide such as (Al,Ga)2O3.

[0074] Other compounds may be added to the SWIR phosphor composition, if the amount added is low enough, so that the desired properties of the resulting SWIR phosphor are not greatly degraded, but may result in benefits such as improved crystallization rate or better densification. Examples for such other compounds are, for example: alkaline earth compounds (such as MgO, CaO or SrO, or the corresponding carbonates), zirconium or hafnium oxides, niobium or tantalum oxides, germanium oxides, silicon dioxide, or other rare earth oxides not explicitly mentioned in the above list.

[0075] IR light emitting device emitting in the wavelength range of 1600-2200 nm with a wavelength conversion structure

[0076] Figure 1An embodiment of an IR light emitting device that emits IR light in the wavelength range of 1600-2200 nm is shown. The IR light emitting device 101 includes a wavelength conversion structure 108. The wavelength conversion structure 108 includes at least one disclosed SWIR phosphor that emits in the wavelength range of 1600-2200 nm. In addition to the wavelength conversion structure 108, the lighting device 101 includes a primary light source 100. The primary light source 100 can be an LED or any other suitable light source, including, for example, a resonant cavity light emitting diode (RCLED) and a vertical cavity laser diode (VCSEL). For example, the primary light source 100 can be a blue emitting LED, or can include a red emitting LED. The primary light source 100 emits a first light 104. A portion of the first light 104 is incident on the wavelength conversion structure 108. The wavelength conversion structure 108 absorbs the first light 104 and emits a second light 112. The wavelength conversion structure 108 can be configured so that little or no first light is part of the final emission spectrum from the device, although this is not required.

[0077] The wavelength conversion structure 108 may include, for example, any SWIR phosphor disclosed herein, such a SWIR phosphor including a (optionally structurally disordered) garnet host lattice, at least one sensitizer ion, and at least one rare earth emitter ion. For example, the wavelength conversion structure 108 may include a SWIR phosphor including a structurally disordered garnet host lattice, Cr(III) sensitizer ions, and Tm(III) and Ho(III) rare earth emitter ions. For example, the wavelength conversion structure 108 may include a SWIR phosphor from a class of garnet materials having the following composition: (Gd 3-u-v-x-y- z Lu x Tm y Ho z Sc v RE u )[Sc 2-a-b-d-e Lu a Cr b Ga d Al e ]{Ga 3-c Al c} 12 , where RE = La, Y, Yb, Nd, Er, Ce and 0≤u≤2,0 <v≤1、0<x≤1、0<y≤0.5、0≤z≤0.05、0<a≤1、0<b≤0.3、0≤c≤3、0<d≤1.8、0≤e≤1.8。

[0078] The wavelength conversion structure 108 may include a SWIR phosphor that can be excited, for example, in the blue spectral range. For example, the light source 100 may be an AlInGaN and / or InGaN type emitter and may emit the first light 104 in the wavelength range of 440-460 nm. The light source 100 may also be a light source that emits the first light 104 in the red spectral range, for example, the light source 100 may be an AlInGaP type emitter that emits a wavelength in the wavelength range of 600-650 nm, or may be an InGaAs type emitter that emits a wavelength in the wavelength range of 700-1000 nm, however, these red emitting light sources may not be as effective as light sources emitting in the blue wavelength range in exciting the SWIR phosphor.

[0079] To improve the conversion efficiency of the SWIR phosphor contained in the wavelength conversion structure 108, additional phosphors may be included, such as a red emitting phosphor that may be excited by a blue emitting primary LED light source. Figure 2 An IR light emitting device 201 is shown, wherein a wavelength conversion structure including one or more of the disclosed SWIR phosphor materials may be further combined with a second phosphor system. Figure 2 In the embodiment of the present invention, the wavelength conversion structure 218 includes a SWIR phosphor portion 208 and a second phosphor portion 202 as part of the IR light emitting device 201, the SWIR phosphor portion 208 including a SWIR phosphor emitting in the range of 1600-2200 nm as disclosed herein. Figure 2 In the embodiment of the present invention, light source 200 may be an LED or any other suitable light source including, as examples, a resonant cavity light emitting diode (RCLED) and a vertical cavity laser diode (VCSEL). Light source 200 emits a first light 204 .

[0080] The first light 204 is incident on a wavelength conversion structure 218, which includes a SWIR phosphor portion 208 and a second phosphor system 202, the SWIR phosphor portion 208 including one or more of the SWIR phosphors disclosed herein. A portion of the first light 204 is incident on the second phosphor portion 202 of the wavelength conversion structure 218. The second phosphor 202 absorbs the first light 204 and emits a third light 206. The third light 206 may have a wavelength range within the excitation range of the SWIR phosphor in the SWIR phosphor portion 208 of the wavelength conversion structure 218. The third light 206 is incident on the SWIR phosphor portion 208. The SWIR phosphor portion 208 absorbs all or part of the third light 206 and emits a fourth light 210. Additionally, a portion of the first light 204 may be incident on the SWIR phosphor portion 208 of the wavelength conversion structure 218. The SWIR phosphor portion 208 may absorb the first light 204 and emit the second light 212 , or the first light 204 may pass through the SWIR phosphor portion 208 .

[0081] The wavelength conversion structure 218 including the SWIR phosphor 208 and the second phosphor 202 may be configured such that little or no first light or third light is part of the final emission spectrum from the device, although this is not required.

[0082] Examples of such second phosphor systems that can be used in the IR light emitting device 201 include examples of phosphor systems disclosed in U.S. Patent Application No. 16 / 393,428, filed on September 13, 2018, and entitled “Infrared Emitting Device,” and incorporated herein by reference in its entirety. In particular, the second phosphor 202 can be, for example, Eu doped 2+ Red emitting materials such as: 2-x Si 5-y Al y O y N 8-y :Eu x BSSNE type phosphors of (M = Ba, Sr, Ca) such as Ba 0.2 Ca 0.06 Sr 1.64 Si 4.98 Al 0.02 O 0.02 N 7.98 :Eu 0.1 ; ingredient is M 1- x SiAlN3:Eu x (M = Sr, Ca) CASN or SCASN type phosphors, such as Ca .985SiAlN3:Eu 0.015 ; or M 1- x LiAl3N4:Eu x (M = Ba, Sr, Ca), such as (Ba 0.5 Ca 0.5 ) 0.995 LiAl3N4:Eu 0.005 ; or M 1-x Li2Al 2- y Si y O 2-y N 2+ y :Eu x (M = Ba, Sr, Ca), such as Sr 0.996 Li2Al 1.996 Si 0.004 O 1.996 N 2.004 :Eu 0.004 , which can crystallize in an ordered structural variant of the UCr4C4 structure type, in which Ba and Ca occupy specific lattice sites. Similar ordered variants are known oxides such as RbNaLi6Si2O8. 0.5 Ca 0.5 ) 1-x LiAl3N4:Eu x In the embodiment, Eu on the Ba site obtains narrowband emission at 630 nm, while Eu on the Ca site obtains NIR emission at wavelengths > 700 nm. In other examples, the second phosphor 202 may be composed of Ca 0.985 SiAlN:Eu 0.015 CASN type phosphors. CASN type red emitting phosphors are commercially available from, for example, Mitsubishi Chemical (BR-101 series).

[0083] The SWIR phosphors disclosed herein can be further combined with dielectric coating structures, for example by using alternating SiO2 and Nb2O5 layers with thicknesses in the range of 40nm-140nm. Dichroic optics (e.g., coatings, filters, or mirrors) that reflect primary pump LED light and transmit phosphor emission light in the SWIR range can be a useful solution to enhance the performance of IR light emitting devices. That is, such dichroic optics can back-reflect blue light, which then has a chance to be reabsorbed by the wavelength conversion structure without changing the emission spectrum provided by the SWIR phosphor.

[0084] exist Figure 2, although the wavelength conversion structure 218 is shown as SWIR phosphor 208 and second phosphor system 202 as two separate blocks, in other embodiments, the wavelength conversion structure SWIR phosphor 208 and second phosphor system 202 can be combined or mixed. The method of forming the wavelength conversion structures 108 and 218 is described in more detail below.

[0085] IR light emitting device emitting in the wavelength range of 1100-2200 nm with a wavelength conversion structure

[0086] The SWIR phosphors disclosed herein that emit in the 1600-2200 nm wavelength range can be further combined with additional IR phosphors to broaden the wavelength range of the IR radiation emitted from the IR light emitting device. For example, the SWIR phosphors disclosed herein can be combined with additional IR phosphors that emit IR light at shorter wavelengths below the 1600-2200 nm wavelength range of the SWIR phosphors disclosed herein to extend the wavelength range of light emitted by the IR light emitting device to shorter wavelengths.

[0087] Reference again Figure 1 , the wavelength conversion structure 108 may include, for example, a SWIR phosphor emitting in the wavelength range of 1600-2200 nm disclosed herein, and an additional IR phosphor. The primary light source 100 emits a first light 104. A portion of the first light 104 is incident on the wavelength conversion structure 108, which in this example includes one or more additional IR phosphors in addition to one or more SWIR phosphors disclosed herein. The wavelength conversion structure 108 absorbs the first light 104 and emits a second light 112. Because the wavelength conversion structure 108 includes both the SWIR phosphor and the additional IR phosphor, the second light 112 emits IR light in a wide wavelength range that includes the wavelength range of the additional IR phosphor and 1600-2200 nm of the SWIR phosphor disclosed herein.

[0088] In one example, the additional IR phosphor included is a shorter wavelength IR emitting phosphor disclosed in U.S. Patent Application Serial No. 17 / 035,233, filed on September 23, 2020, entitled “SWIRpcLED and Phosphor Emitting in the 1100-1700nm Range,” which is incorporated herein by reference in its entirety. In particular, the additional IR phosphor may be one or more doped Ni-doped phosphors emitting in the 1000-1700nm range. 2+ Or Ni 2+ and Cr 3+ For example, the additional IR phosphor may include Li 0.5-0.5x (Ga,Sc) 2.5-0.5x-y O4:Ni x , Cr y (where 0 ≤ x ≤ 1, 0 < y ≤ 0.1, 0 ≤ z ≤ 1, 0 ≤ u ≤ 0.2) a spinel-type additional IR phosphor, and device 101 may include an AlInGaP-type LED emitting at 620 - 630 nm in primary light source 100. More specifically, device 101 may have a wavelength conversion structure 108 that includes Li 0.49 Sc 0.05 Ga 2.384 O4:Ni 0.013 , Cr 0.05 a spinel-type additional IR phosphor, and may include an AlInGaP-type LED emitting at 622 nm as primary light source 100. Combining such an additional IR phosphor with the SWIR phosphor disclosed herein that emits in the 1600 - 2200 nm wavelength range extends the IR emission range of device 101 to shorter wavelengths than the 1600 nm - 2200 nm range, such that lighting device 101 emits within 1100 nm - 2200 nm.

[0089] In another example, in an IR-emitting device having a broader IR emission range, the additional IR phosphor included may also require an additional second phosphor system, similar to the second phosphor system for the SWIR phosphor described above. Referring again to Figure 2 , the second phosphor system for the additional IR phosphor can broaden the spectral range that allows for effective excitation of the additional IR phosphor, and thereby increase the number of types of primary light sources 200 that can be used in device 201. That is, the additional second phosphor system for the additional IR phosphor 202 may or may not include the above-described second phosphor system for the SWIR phosphor disclosed herein. This additional second phosphor system absorbs first light 204 from primary light source 200, which emits light outside the wavelength range required to excite the additional IR phosphor. For example, the additional second phosphor system 202 may absorb first light 204 emitted from a blue or green LED as primary light source 200. The second phosphor system 202 then emits third light 206 within the red spectral range. The third light 206 emitted from the second phosphor system 202 excites the additional IR phosphor portion 208.

[0090] For example, device 201 may include phosphors that emit from green to red, such as Eu 2+Phosphor, added as an additional second phosphor system 202, and a blue emitting LED may be used as the primary light source 200. Examples of red emitting phosphors for use in the additional second phosphor system 202 include (Sr, Ca)AlSiN3:Eu and (Ba, Sr, Ca)2Si 5- x Al x O x N 8-x :Eu.

[0091] In the example device, the primary light source 200 may be an InGaN type emitter emitting blue light. The wavelength conversion structure 218 may include an orange-red emitting (Ba,Sr)2Si5N8:Eu phosphor as the additional second phosphor system 202 and a Li 0.5-0.5x (Ga,Sc) 2.5-0.5x-y O4:Ni x ,Cr y Spinel phosphors and SWIR phosphors as disclosed herein. In particular, the device 201 may include an InGaN type emitter emitting 440-460 nm as the primary light source 200 and a wavelength conversion structure 218 including an orange-red emitting phosphor (Ba 0.4 Sr 0.6 ) 2-x Si5N8:Eu 0.02 and Li as an additional IR phosphor 0.49 Sc 0.05 Ga 2.384 O4:Ni 0.013 ,Cr 0.05 The additional second phosphor system 202 may include a Cr-doped 3+ The phosphor is doped with Cr 3+ The phosphor emits in the 700-1000nm wavelength range and can be excited in the blue to green and red spectral range. 3+ The emission light of the phosphor is doped with Ni 2+ The additional second phosphor system 202 may include other Ni 2+ Phosphor systems. Examples include LaMgGa 11 O 19 :Ni, MgO:Ni, MgF2:Ni, Ga2O3:Ni,Ge, or the composition is RE2AEMg2TV3O 12: Garnets of Ni(RE = Y, La, Lu, Gd, Nd, Yb, Tm, Er; AE = Ca, Sr; TV = Si, Ge).

[0092] IR light emitting device with temperature-stabilized emission in the wavelength range of 1300-2000nm

[0093] A luminescent device can exhibit favorable temperature stability in various portions of its emission spectrum (e.g., at approximately 1650 nm, 1720 nm, and 1820 nm), the luminescent device comprising: at least one primary light source (e.g., InGaN LED) emitting in the blue spectral range; Cr 3+ and Ni 2+ co-doped garnet SWIR phosphor compositions having a peak emission wavelength in the range of 1400 - 1600 nm and the general formula (Gd 3-u RE u )[Ga 2-a-b-d-e Ni a Cr b L d Al e {Ga 3-c Al c}O 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0 ≤ u ≤ 2, 0 < a ≤ 0.1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 < d ≤ 0.15, 0 ≤ e ≤ 2; and Cr 3+ and Tm 3+ co-doped garnet phosphor compositions having a peak emission wavelength in the range of 1600 - 1900 nm and the general formula (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Sc d Al e {Ga 3-c Al c}O 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0 ≤ u ≤ 2, 0 < y ≤ 1.5, 0 ≤ a ≤ 1, 0 < b ≤ 0.3, 0 ≤ c ≤ 3, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 1.8.

[0094] This temperature stability results from the compensation of the temperature-dependent trends of two different phosphor families. As the temperature increases, the emission from the Ni 2+ phosphor in the range of 1400 - 1500 nm is quenched. For wavelengths less than about 1800 nm, from Tm3+ The emission of the phosphor increases with temperature and for wavelengths greater than about 1800 nm, the emission from Tm 3+ The emission of phosphors decreases with temperature. For mixtures of different phosphors, these trends can be balanced against each other to provide temperature stability in important regions of the emission spectrum. 3+ Phosphor and Ni 2+ The weight ratio of the phosphor may be, for example, 0.25 to 1.5 (preferably 0.43 to 1.0) to provide such temperature stability.

[0095] In contrast, at about 1500 nm, the temperature dependencies of the two phosphors reinforce each other. This makes the emission at 1500 nm from this phosphor mixture particularly sensitive to temperature, allowing it to be used as a measure of temperature.

[0096] Absorption by the matrix material (eg, silicone) in which the phosphor is dispersed can also affect the temperature dependence and stability of the emission from the mixture.

[0097] Reference again Figure 1 , a mixture of two phosphors can be provided in a single wavelength conversion structure 108. For example, the phosphor mixture can be dispersed in a silicone matrix. The silicone matrix can be, for example, a commercially available methyl phenyl silicone as is commonly used in lighting class mid-power LED packaging, or a commercially available polydimethylsiloxane type encapsulant as is used in phosphor integration in chip-on-board (COB) type LED modules.

[0098] Alternatively, the phosphor may be in the form of a ceramic. The ceramic may be applied separately to different primary light sources. That is, the light emitting device may include, for example, Figure 1 In the two arrangements shown in FIG. 1 , one wavelength conversion structure 108 includes Tm in the form of a ceramic. 3+ phosphor, and another wavelength conversion structure 108 includes Ni in ceramic form. 2+ Phosphor. Alternatively, the wavelength conversion structure 108 may include a stack of ceramic phosphors. The stack may, for example, include a ceramic of one phosphor type sandwiched between ceramics of another phosphor type. This may reduce stress and strain in the stack.

[0099] You can also use something like Figure 2 The arrangement of the arrangement shown in .

[0100] like Figure 1 and Figure 2As shown in , an IR light emitting device may include a wavelength conversion structure that can be used with, for example, light sources 100, 200. Light sources 100, 200 may be light emitting diodes (LEDs). Light emitted by the light emitting diodes is absorbed by the phosphor in the wavelength conversion structure according to an embodiment and emitted at a different wavelength. Figure 3 An example of a suitable light emitting diode (a blue-emitting III-nitride LED) is shown for use in a lighting device (such as reference Figure 2 The disclosed lighting device) is used in which the SWIR phosphor and / or the additional IR phosphor are combined with a second phosphor and / or an additional second phosphor that absorbs blue light and emits SWIR light.

[0101] Although in the examples described below, the semiconductor light-emitting device is a Group III nitride LED that emits blue light or UV light, semiconductor light-emitting devices other than LEDs, such as laser diodes and semiconductor light-emitting devices made of other material systems, such as other III-V materials, III-phosphides, III-arsenides, II-VI materials, ZnO or Si-based materials, may be used, for example, depending on the wavelength range required to excite the SWIR phosphor or the combination of the SWIR phosphor and the second phosphor in the wavelength conversion structure.

[0102] Figure 3 A III-nitride LED 1 that can be used in embodiments of the present disclosure is shown. Any suitable semiconductor light emitting device can be used, and embodiments of the present disclosure are not limited to Figure 3 As is known in the art, the device shown in FIG. is formed by growing a III-nitride semiconductor structure on a growth substrate 10. Figure 3 The growth substrate is typically sapphire, but can be any suitable substrate, such as, for example, SiC, Si, GaN, or a composite substrate. The surface of the growth substrate on which the III-nitride semiconductor structure is grown can be patterned, roughened, or textured prior to growth, which can improve light extraction from the device. Before or after growth, the surface of the growth substrate opposite the growth surface (i.e., the surface through which most of the light is extracted in a flip-chip configuration) can be patterned, roughened, or textured, which can improve light extraction from the device.

[0103] The semiconductor structure includes a light-emitting or active region sandwiched between an n-type region and a p-type region. The n-type region 16 can be grown first and can include multiple layers of different compositions and doping concentrations, including, for example, preparation layers (such as buffer layers or nucleation layers), and / or layers designed to facilitate removal of the growth substrate (which can be n-type or unintentionally doped), and n-type device layers or even p-type device layers designed to be used for the light-emitting region to effectively emit light with specific optical, material or electrical properties desired. The light-emitting or active region 18 is grown on top of the n-type region. Examples of suitable light-emitting regions include a single thick or thin light-emitting layer, or a multi-quantum well light-emitting region including multiple thin or thick light-emitting layers separated by barrier layers. A p-type region 20 can then be grown on top of the light-emitting region. Like the n-type region, the p-type region can include multiple layers of different compositions, thicknesses and doping concentrations, including unintentionally doped layers or n-type layers.

[0104] After growth, a p-contact is formed on the surface of the p-type region. The p-contact 21 typically includes multiple conductive layers, such as a reflective metal and a protective metal, which can prevent or reduce electromigration of the reflective metal. The reflective metal is typically silver, but any suitable material or materials can be used. After forming the p-contact 21, the p-contact 21, the p-type region 20, and a portion of the active region 18 are removed to expose a portion of the n-type region 16 on which the n-contact 22 is formed. The n and p contacts 22 and 21 are electrically isolated from each other by a gap 25, which can be filled with a dielectric, such as an oxide of silicon or any other suitable material. Multiple n-contact vias can be formed; the n-contact 22 and the p-contact 21 are not limited to vias. Figure 3 The arrangement shown in . As is known in the art, the n and p contacts can be redistributed to form bond pads with a dielectric / metal stack.

[0105] To form electrical connections to LED 1, one or more interconnects 26 and 28 are formed on or electrically connected to n and p contacts 22 and 21. Interconnect 26 is electrically connected to Figure 3 2. Interconnect 28 is electrically connected to p-contact 21. Interconnects 26 and 28 are electrically isolated from n- and p-contacts 22 and 21 and from each other by dielectric layer 24 and gap 27. Interconnects 26 and 28 may be, for example, solder, stud bumps, a gold layer, or any other suitable structure.

[0106] The substrate 10 may be thinned or completely removed. In some embodiments, the surface of the substrate 10 exposed by the thinning is patterned, textured, or roughened to improve light extraction.

[0107] According to the embodiments of the present disclosure, any suitable light emitting device can be used in the light source. Figure 3 The specific LEDs shown in FIG. Figure 3 The LEDs shown in Figure 4 , Figure 5 and Figure 6 It is shown by box 1.

[0108] SWIR phosphors and formation of wavelength conversion structures including SWIR phosphors

[0109] The SWIR phosphors disclosed herein can be formed using any suitable method. In one exemplary method, stable compounds, such as, for example, oxides (which contain elements to form a garnet body, sensitizer ions, and rare earth elements) are mixed in appropriate ratios by, for example, ball milling. The mixture can then be fired at a high temperature (e.g., in excess of 1500° C.), with ball milling in between. The obtained powder can then be washed, dried, and sieved, for example, with water to form a powder of a SWIR phosphor material having a particle diameter within a range determined by the sieve, for example, less than 50 μm when a 50 μm sieve is used. The resulting SWIR phosphor powder is then used to form a wavelength conversion structure as described herein.

[0110] Relative to Figure 1 The described wavelength conversion structure 108, which may include one or more SWIR phosphors, or a combination of one or more SWIR phosphors and one or more additional IR phosphors, may be manufactured, for example, in powder form, ceramic form, or any other suitable form. The wavelength conversion structure 108 may be formed as one or more structures that are formed and disposed of separately from the light source, such as prefabricated glass or ceramic tiles, or may be formed as a structure formed in situ with the light source, such as a conformal coating or other coating formed on or over the light source.

[0111] In some embodiments, the wavelength conversion structure 108 can be a powder dispersed in, for example, a transparent matrix, a glass matrix, a ceramic matrix, or any other suitable material or structure. The SWIR phosphor dispersed in the matrix can, for example, be segmented or formed into tiles disposed above the light source. The glass matrix can be, for example, a low melting point glass having a softening point below 1000° C., or any other suitable glass or other transparent material. The ceramic matrix material can, for example, be a fluoride salt (such as CaF2) or any other suitable material.

[0112] The SWIR phosphor or a combination of a SWIR phosphor and an additional IR phosphor can be applied in powder form (wherein, for example, the average diameter of the particles is in the range of 3-50 μm) to form a wavelength conversion structure. The powder can be dispersed in a curable polysiloxane type resin and applied by means of, for example, dispensing into a package comprising a primary light emitting LED. The powder can also be mixed with a low melting point glass powder and heated to above the softening temperature of the glass to form the phosphor in a glass converter structure (PiG). Alternatively, the SWIR phosphor can be mixed into a silicone resin and cast or attached to a glass substrate to form a phosphor on glass structure (PoG).

[0113] The wavelength conversion structure 108 can be formed, for example, by mixing a powdered SWIR phosphor or a combination of a powdered SWIR phosphor and a powdered additional SWIR phosphor with a transparent material (such as silicone) and dispensing or otherwise arranging it in the light path. In powder form, the average particle size (e.g., particle diameter) of the SWIR phosphor and the additional IR phosphor can be at least 1 μm in some embodiments, not more than 50 μm in some embodiments, at least 5 μm in some embodiments, and not more than 20 μm in some embodiments. In some embodiments, individual SWIR phosphor particles or layers of powdered SWIR phosphor can be coated with one or more materials, such as silicates, phosphates, and / or one or more oxides, for example to improve absorption and luminescence properties and / or to increase the functional lifetime of the material.

[0114] The wavelength conversion structure of the second phosphor system and / or the additional second phosphor system (such as relative to Figure 2 The wavelength conversion structure 218) can be manufactured using the same method described above with respect to the wavelength converter 108.

[0115] The SWIR phosphor and the second phosphor and / or the additional IR phosphor and the additional second phosphor may be mixed together in a single wavelength conversion layer or formed as separate wavelength conversion layers. In a wavelength conversion structure with a separate wavelength conversion layer, the SWIR phosphor and the second phosphor and / or the additional IR phosphor and the additional second phosphor may be stacked so that the second phosphor (and / or the additional second phosphor) may be disposed between the SWIR phosphor (and / or the additional IR phosphor) and the light source, or the SWIR phosphor (and / or the additional IR phosphor) may be disposed between the second phosphor (and / or the additional second phosphor) and the light source.

[0116] Figure 4 , Figure 5 and Figure 6 FIG. 4 shows a device combining an LED 1 and a wavelength conversion structure 30. According to the above embodiments and examples, the wavelength conversion structure 30 may be, for example, Figure 1 The wavelength conversion structure 108 including the SWIR phosphor shown in FIG. Figure 2 The wavelength conversion structure 218 with a SWIR phosphor and a second phosphor is shown in FIG.

[0117] exist Figure 4 In the embodiment, the wavelength conversion structure 30 is directly connected to the LED 1. For example, the wavelength conversion structure can be directly connected to Figure 3 The substrate 10 shown in FIG. 1 is connected to the semiconductor structure, or directly to the semiconductor structure if the substrate 10 is removed.

[0118] exist Figure 5 In the embodiment of the present invention, wavelength conversion structure 30 is disposed near LED 1 but is not directly connected to LED 1. For example, wavelength conversion structure 30 may be separated from LED 1 by adhesive layer 32, a small air gap, or any other suitable structure. In some embodiments, the spacing between LED 1 and wavelength conversion structure 30 may be, for example, less than 500 μm.

[0119] exist Figure 6 In the embodiment of the present invention, the wavelength conversion structure 30 is spaced apart from the LED 1. In some embodiments, the spacing between the LED 1 and the wavelength conversion structure 30 may be, for example, in the order of millimeters. Such a device may be referred to as a "remote phosphor" device.

[0120] The wavelength conversion structure 30 may be square, rectangular, polygonal, hexagonal, circular, or any other suitable shape. The wavelength conversion structure may be the same size as the LED 1 , larger than the LED 1 , or smaller than the LED 1 .

[0121] Multiple wavelength converting materials and multiple wavelength converting structures can be used in a single device.

[0122] In addition to the above-mentioned SWIR phosphors, second phosphors, additional IR phosphors and / or additional second phosphors, the device may also include other wavelength conversion materials, such as, for example, conventional phosphors, organic phosphors, quantum dots, organic semiconductors, II-VI or III-V semiconductors, II-VI or III-V semiconductor quantum dots or nanocrystals, dyes, polymers, or other luminescent materials.

[0123] Multiple wavelength converting materials may be mixed together or formed into separate structures.

[0124] In some embodiments, other materials may be added to the wavelength conversion structure or device, such as, for example, materials that improve optical performance, materials that promote scattering, and / or materials that improve thermal performance. An example of such a material is (Al,Ga)2O3 as a second phase in the polycrystalline ceramic of the structurally disordered cubic garnet SWIR phosphor disclosed herein.

[0125] IR Spectrometer

[0126] Fig. 7A A schematic diagram of an IR spectrometer 700A is shown. A light emitting device (such as Figure 1 and Figure 2 101, 201) can be used in a spectrometer device for IR absorption or reflection spectroscopy applications. In FIG7, the IR spectrometer 700 includes an IR light emitting device 710, which can include one or more SWIR phosphors or a combination of SWIR phosphors and additional IR phosphors (with or without a second phosphor system or an additional second phosphor system, respectively), such as light emitting devices 101, 201. The IR light source 710 can also be an IR light source array, such as the one described below with reference to Fig. 8A and Figure 8B those described. The IR spectrometer 700 also includes a sensor / detector 730 for sensing IR light, which may be, for example, a photoresistor or a photodiode which may be further combined with a photoconductive and / or diffractive element. In one example, the sensor / detector 730 is specifically formed to detect IR light (particularly in miniaturized devices) and includes a lead chalcogenide (PbS, PbSe) based photoresistor sensing element, for example formed as a thin film PbS, which may detect IR radiation in the wavelength range of 1000-3000 nm. In order to provide spectral resolution, sensing elements such as PbS photoresistors may be combined with an array of filter elements such as, for example, a bandpass filter. The IR spectrometer 700 may further include, for example, a processor 740 for processing data received from the sensor / detector 730. The processor 740 may include controller functionality for controlling the IR light emitting device 710 and / or the sensor detector 730. As shown in FIG. 7 , the IR spectrometer 700 may also include a location for a sample 720 if the sample is to be inserted into the IR spectrometer between the IR light emitting device 710 and the sensor detector 730 .

[0127] exist Figure 7B In the example IR spectrometer 700B shown in FIG. 1 , the sensor / detector 730 is positioned to detect IR light emitted from the IR light emitting device 710 through the window 750 and reflected back to the detector by a sample (e.g., human skin) located outside the IR spectrometer through the window 750 and a wavelength selective element (e.g., filter) 760. Thus, the sensor / detector detects the reflected spectrum. This type of IR spectrometer may be particularly suitable for use in a smartphone, other handheld device, or wearable device.

[0128] In operation of devices 700A and 700B, IR light emitting device 710 emits infrared light 705, which may be broadband emission in the range of 1600-2200 nm, or broader in the range of 1100-2200 nm, depending on the phosphor combination in the wavelength conversion structure of IR light emitting device 710. The emitted light enters sample 720 (or reflects off sample 720, depending on the configuration), and the IR light of the IR absorption spectrum exits sample 720 (or reflects off sample 720) to be detected by sensor / detector 730.

[0129] In one variation, the IR spectrometer includes one or more light emitting devices 710 configured as described above under the heading "IR light emitting device with temperature-stable emission in the wavelength range of 1300-2000 nm." Such a light source can provide IR emission in the range of 1300-2000 nm, with very high temperature stability at emission wavelengths of approximately 1720 nm, 1820 nm, and 1650 nm. At these wavelengths, the ratio of the sebum absorption coefficient to the water absorption coefficient is high, medium, and low, respectively. Therefore, reflection absorption measurements at these wavelengths can be used, for example, by the methods described in Ezerskaia et al., "Quantitative and simultaneous non-invasive measurement of skin hydration and sebum levels," Biomedical Optics Express 2311 (2016), to determine skin hydration and sebum levels. For example, the spectrometer can be incorporated into a smartphone, other handheld device, or wearable device.

[0130] IR Transmitter Array

[0131] Figure 8A-B A cross-sectional view and a top view of an array 800 of SWIR pcLEDs 810 are shown, respectively. The SWIR pcLEDs 810 may be configured as follows, respectively. Figure 1 , Figure 2and the lighting device 101, 201 or 710 shown in Figure 7, which includes a wavelength converter including one or more of the SWIR phosphors disclosed herein (which are included in the phosphor pixel 806), wherein the semiconductor diode 812 is disposed on the substrate 802. The wavelength converter may include one or more SWIR phosphors or a combination of a SWIR phosphor and an additional IR phosphor, with or without a second phosphor system and / or an additional second phosphor system as described above. Such an array may include any suitable number of SWIR pcLEDs arranged in any suitable manner. In the illustrated example, the array 800 is depicted as being monolithically formed on a shared substrate, but alternatively, the SWIR pcLED array may be formed from separate individual pcLEDs. The substrate 802 may optionally include CMOS circuitry for driving the LEDs and may be formed from any suitable material.

[0132] although Figure 8A-B A three-by-three array of nine pcLEDs is shown, but such an array may include, for example, tens, hundreds, or thousands of LEDs. The width (e.g., side length) of each LED (pixel) in the plane of the array may be, for example, less than or equal to 1 millimeter (mm), less than or equal to 500 microns, less than or equal to 100 microns, or less than or equal to 50 microns. The LEDs in such an array may be spaced apart from each other by streets or lanes having a width in the plane of the array of, for example, hundreds of microns, less than or equal to 100 microns, less than or equal to 50 microns, less than or equal to 10 microns, or less than or equal to 5 microns. Although the example shown shows rectangular pixels arranged in a symmetrical matrix, the pixels and array may have any suitable shape or arrangement.

[0133] LEDs having a dimension in the plane of the array (eg, a side length) less than or equal to about 50 microns are generally referred to as micro-LEDs, and an array of such micro-LEDs may be referred to as a micro-LED array.

[0134] Arrays of LEDs, or portions of such arrays, may be formed as segmented monolithic structures in which individual LED pixels are electrically isolated from one another by trenches and / or insulating materials, but in which the electrically isolated segments remain physically connected to one another via portions of the semiconductor structure.

[0135] Each LED in the LED array can be individually addressable, can be addressable as part of a group or subset of pixels in the array, or can be non-addressable. Therefore, for any application that requires or benefits from fine-grained intensity, spatial and temporal control of light distribution, the luminous pixel array is useful. These applications may include, but are not limited to, precise special patterning of the emitted light from a pixel block or individual pixels. Depending on the application, the emitted light can be spectrally distinct, adaptive over time, and / or environmentally responsive. Such a luminous pixel array can provide pre-programmed light distribution with various intensity, space, or time patterns. The emitted light can be based at least in part on received sensor data and can be used for optical wireless communication. The associated electronic devices and optical devices can be distinct at the pixel, pixel block, or device level.

[0136] like Figure 9A-9B As shown in , the SWIR pcLED array 800 can be mounted on an electronic board 900, which includes a power and control module 902, a sensor module 904, and an LED attachment area 906. The power and control module 902 can receive power and control signals from an external source and signals from the sensor module 904, and the power and control module 902 controls the operation of the LEDs based on these signals. The sensor module 904 can receive signals from any suitable sensor (e.g., from a temperature or light sensor). Alternatively, the SWIR pcLED array 800 can be mounted on a board (not shown) separate from the power and control module and the sensor module.

[0137] Each SWIR pcLED may optionally be combined or arranged in combination with a lens or other optical element positioned adjacent to or disposed on the phosphor layer. Such optical elements, not shown in the figures, may be referred to as "primary optical elements". Figure 10A-10B As shown in , SWIR pcLED array 800 (e.g., mounted on electronic board 900) can be arranged in combination with secondary optical elements (such as waveguides, lenses, or both) for use in the intended application. Fig. 10A In FIG. 1 , light emitted by SWIR pcLED 810 is collected by waveguide 1002 and directed to projection lens 1004. For example, projection lens 1004 may be a Fresnel lens. Fig. 10B In the embodiment of the present invention, the light emitted by the SWIR pcLED 810 is collected directly by the projection lens 1004 without the use of an intervening waveguide. This arrangement may be particularly suitable when the SWIR pcLEDs can be spaced sufficiently close to each other, and may also be used in various applications. For example, micro-LED display applications may use a similar Figure 10A-10BIn general, any suitable arrangement of optical elements may be used in conjunction with the LED arrays described herein, depending on the desired application.

[0138] An array of independently operable LEDs can be used in conjunction with a lens, lens system, or other optical system (e.g., as described above) to provide lighting suitable for a particular purpose. For example, in operation, such an adaptive lighting system can provide lighting that changes wavelength and / or intensity across an illuminated sample or object, and / or is aimed in a desired direction. The controller can be configured to receive data indicating the position and spectral characteristics of an object or person in a scene, and based on this information, control the LEDs in the LED array to provide lighting suitable for the scene. Such data can be provided by, for example, an image sensor, an optical (e.g., laser scanning) sensor, or a non-optical (e.g., millimeter wave radar) sensor. Such adaptive lighting is increasingly important for mobile devices, VR, and AR applications.

[0139] Fig.11 An example smartphone 1100 is schematically shown including a (optionally SWIR) pcLED array and a lens system 1102, which may be similar or identical to the systems described above. The flash system 1100 may also include a pcLED driver 1106 controlled by a controller 1104, such as a microprocessor. The controller 1104 may also be coupled to a camera 1107 and a sensor 1108, and operate according to instructions and profiles stored in a memory 1110. The camera 1107 and the adaptive lighting system 1102 may be controlled by the controller 1104 to match their fields of view.

[0140] Sensors 1108 may include, for example, position sensors (e.g., gyroscopes and / or accelerometers) and / or other sensors that may be used to determine the position, velocity, and orientation of system 1100. Signals from sensors 1108 may be provided to controller 1104 for use in determining an appropriate course of action for controller 1104 (e.g., which LEDs are currently illuminating a target, and which LEDs will illuminate the target after a predetermined amount of time).

[0141] In some variations, sensor 1108 may include a SWIR light source as described above and / or a Figure 7A-7B The IR spectrometer described. IR spectrometers can be used, for example, to determine skin hydration and sebum levels.

[0142] In operation, the illumination from some or all pixels of the LED array in 1102 may be adjusted (deactivated, operated at full intensity, or operated at an intermediate intensity). Beam focusing or steering of light emitted by the LED array in 1102 may be performed electronically by activating one or more subsets of pixels to allow dynamic adjustment of the beam shape without moving the optics or changing the focus of a lens in the lighting device.

[0143] Fig.12 An example display (e.g., AR / VR / MR) system 1200 is schematically shown, which includes an adaptive light array 1210, a display 1220, a light array controller 1230, a sensor system 1240, and a system controller 1250. Control input is provided to the sensor system 1240, while power and user data input are provided to the system controller 1250. In some embodiments, the modules included in the system 1200 can be compactly arranged in a single structure, or one or more elements can be separately mounted and connected via wireless or wired communication. For example, the light array 1210, the display 1220, and the sensor system 1240 can be mounted on a headset or glasses, where the light controller and / or the system controller 1250 are separately mounted.

[0144] Light emitting array 1210 may include one or more adaptive light emitting arrays, as described above, which may be used, for example, to project light in a graphic pattern or object pattern that may support an AR / VR / MR system. In some embodiments, a micro-LED array may be used.

[0145] System 1200 may incorporate a variety of optics in adaptive light emitting array 1210 and / or display 1220 , for example, to couple light emitted by adaptive light emitting array 1210 into display 1220 .

[0146] Sensor system 1240 may include, for example: external sensors to monitor the environment, such as cameras, depth sensors, or audio sensors; and internal sensors to monitor the position of the AR / VR / MR headset, such as accelerometers or two-axis or three-axis gyroscopes. Other sensors may include, but are not limited to, air pressure, strain sensors, temperature sensors, or any other suitable sensor required for local or remote environmental monitoring. In some embodiments, control inputs may include detected touches or taps, gesture inputs, or controls based on the position of the headset or display. In some variations, sensor 1240 may include a SWIR light source as described above.

[0147] In response to data from the sensor system 1240, the system controller 1250 can send images or instructions to the light array controller 1230. Changes or modifications to the images or instructions can also be made through user data input or automatic data input as needed. User data input can include, but is not limited to, data input provided by audio commands, tactile feedback, eye or pupil positioning, or a connected keyboard, mouse, or game controller.

[0148] Example:

[0149] In the following examples, compositions of the SWIR phosphors disclosed herein and pcLEDs including these SWIR phosphors are described.

[0150] Example 1

[0151] Example 1 describes a Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12 A SWIR phosphor with a composition of Gd was synthesized by combining 28.7 g of gadolinium oxide (Treibacher, >99.98%), 7.66 g of scandium oxide (Treibacher, 99.99%), 3.65 g of lutetium oxide (Rhodia, 99.99%), 11.6 g of gallium oxide (Dowa Electronics Materials, 4N), 0.236 g of chromium (II) oxide (Alfa Aesar, 98%), 6.22 g of aluminum oxide (Baikowski, SP-DBM), 0.128 g of holmium oxide (K. Rasmus & Co, 4N), 2.027 g of thulium oxide (Alfa Aesar, >99.9%), and 1.01 g of gadolinium fluoride (Materion, 4N). 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12SWIR phosphor. These compounds were mixed by planetary ball milling. The mixture was then fired at 1540°C for 8 hours in an air atmosphere, followed by ball milling, and then fired at 1510°C for 8 hours in an air atmosphere. After the second firing of the mixture, the mixture was pulverized and ball milled to obtain a powder of the SWIR phosphor. The SWIR phosphor powder was washed with water, dried at 300°C in air, and finally sieved through a 50 μm sieve.

[0152] Fig.13 The Gd obtained in Example 1 is shown. 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12 X-ray powder pattern 1300 of a SWIR phosphor (copper radiation). Grey line 1310 indicates the position and height of the fitted reflection calculated using the cubic garnet structure model. Example a shows The cubic lattice constant and 6.38 g / cm 3 The calculation density of .

[0153] Fig.14 The Gd obtained in Example 1 is shown. 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O 12 Scanning electron microscope (SEM) image 1400 of SWIR phosphor powder.

[0154] Fig.15 A power reflection spectrum 1500 in the visible spectral range is shown for Example 1. The reflection minimum 1510 in the visible spectral range is in the blue spectral region at approximately 450 nm.

[0155] Example 2

[0156] Example 2 describes the formation of a SWIR pcLED including the SWIR phosphor synthesized in Example 1. The Gd 2.367 Ho 0.01 Tm 0.152 Sc 1.6 Lu 0.27 Ga 1.8 Al 1.78 Cr 0.04 O12 The powder was mixed with a thermally curable silicone (phosphor / silicone weight ratio of 1.6) to form a SWIR pcLED including the SWIR phosphor of Example 1. The mixture of SWIR phosphor and thermally curable silicone was dispensed into a mid-power LED package containing an InGaN blue emitter (emission wavelength ~450 nm).

[0157] Fig.16 A normalized short wave infrared emission spectrum 1600 of the SWIR pcLED formed in Example 2 is shown. The emission spectrum shows that the emission from the SWIR pcLED covers the range of 1610-2130 nm. For the wavelength range 1610-2130 nm, the minimum 161 and average 162 emission powers relative to the maximum emission power are greater than 12% and 53% (dotted and dashed lines), respectively.

[0158] Example 3

[0159] Example 3 describes a Gd 2.59 Tm 0.24 Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12 A SWIR phosphor with a composition of Gd was synthesized by combining 29.56 g of gadolinium oxide (Treibacher, >99.98%), 3.39 g of scandium oxide (Treibacher, 99.99%), 3.87 g of lutetium oxide (Rhodia, 99.99%), 12.34 g of gallium oxide (Dowa Electronics Materials, 4N), 0.493 g of chromium (II) oxide (Alfa Aesar, 98%), 6.22 g of aluminum oxide (Baikowski, SP-DBM), 0.255 g of holmium oxide (K. Rasmus & Co, 4N), 2.995 g of thulium oxide (Alfa Aesar, >99.9%), and 1.04 g of gadolinium fluoride (Materion, 4N). 2.59 Tm 0.24 Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12SWIR phosphor. These compounds were mixed by planetary ball milling. The mixture was then fired at 1540°C for 8 hours in an air atmosphere, followed by ball milling, and then fired at 1510°C for 8 hours in an air atmosphere. After the second firing of the mixture, the mixture was pulverized and ball milled to obtain a SWIR phosphor powder. The SWIR phosphor powder was washed with water, dried at 300°C in air, and finally sieved through a 50 μm sieve.

[0160] Fig.17 The composition of Example 3 is shown to be Gd 2.59 Tm 0.24 Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12 X-ray powder pattern 1700 (copper radiation) of a SWIR phosphor. Grey line 1710 indicates the position and height of the fitted reflection calculated using the cubic garnet structure model. Example a shows The cubic lattice constant and 6.62 g / cm 3 The calculation density of .

[0161] Example 4

[0162] Example 4 describes the formation of a SWIR pcLED including the SWIR phosphor synthesized in Example 3. The Gd 2.59 Tm 0.24 Ho 0.02 Sc 0.75 Lu 0.3 Ga2Al2Cr 0.1 O 12 The powder was mixed with a thermally curable silicone (phosphor / silicone weight ratio of 1.6) to form a SWIR pcLED including the SWIR phosphor of Example 3. The mixture of SWIR phosphor and thermally curable silicone was dispensed into a mid-power LED package containing an InGaN blue emitter (emission wavelength ~450 nm).

[0163] Fig.18 A normalized short wave infrared emission spectrum 1800 of the SWIR pcLED formed in Example 4 is shown. The emission spectrum shows that the emission from the SWIR pcLED covers a spectral range of 1600-2130 nm. For the wavelength range of 1610-2130 nm, the minimum 181 and average 182 emission powers relative to the maximum emission power are greater than 12% and 46% (dotted and dashed lines), respectively.

[0164] Example 5

[0165] Example 5 describes the formation of a wavelength conversion structure as a composite ceramic plate including a SWIR garnet phosphor component Gd2Ho as the primary polycrystalline phase. 0.013 Tm 0.2 Sc 0.67 Lu 0.24 Ga 1.6 Al 3.2 Cr 0.08 O 12 The SWIR phosphor component Gd2Ho was prepared by combining 89.92 g of gadolinium oxide (Treibacher, >99.98%), 11.58 g of scandium oxide (Treibacher, 99.99%), 11.85 g of lutetium oxide (Rhodia, 99.99%), 37.18 g of gallium oxide (Dowa Electronics Materials, 4N), 1.512 g of chromium (II) oxide (Alfa Aesar, 98%), 40.46 g of aluminum oxide (Baikowski, SP-DBM), 0.611 g of holmium oxide (K. Rasmus & Co, 4N), and 9.57 g of thulium oxide (Alfa Aesar, >99.9%). 0.013 Tm 0.2 Sc 0.67 Lu 0.24 Ga 1.6 Al 3.2 Cr 0.08 O 12 . These compounds were mixed in 99 g of ethanol and 107 μL of tetraethyl orthosilicate (Merck, pa) by means of ball milling and the addition of a dispersant (2 wt % Malialim AKM-0531) until an average particle size of 0.72 μm was reached. After the addition of a polyvinyl butyral binder and a plasticizer system (Sekisui BL-5, G-260), the ceramic tapes were cast, dried, stacked and laminated. After debinding at 600 ° C, the ceramic plates were sintered at 1580 ° C in an air atmosphere for 8 h. The obtained composite ceramic with a thickness of 197 μm was mainly characterized by a lattice constant of 1.34 W / cm2. The cubic garnet structure crystallizes with some (Al,Ga)2O3 secondary phases.

[0166] Fig.19 A scanning electron micrograph of a sintered SWIR phosphor ceramic is shown 1900. The light colored ceramic grains 1910 are the garnet phosphor phase, while the dark colored ceramic grains 1920 are composed of the (Al,Ga)2O3 secondary phase.

[0167] Example 6

[0168] The SWIR phosphor composite ceramic of Example 5 was coated with silicon dioxide and niobium oxide layers to obtain a dichroic coating according to the recipe in Table 1 below. The coating was applied on the surface of the sintered ceramic by reactive sputtering using silicon and niobium metal targets and oxygen as reactive gas.

[0169] Table 1

[0170]

[0171] Fig. 20 A graph 2000 is shown of the light transmittance of the coated ceramic of this example as a function of wavelength, obtained for an angle of incidence of 0°.

[0172] Example 7

[0173] After cutting the ceramic prepared in Example 6 into small pieces with a size of 1060×1060 μm, the obtained converter structure (with the uncoated surface) was attached to a 1 mm 2 440nm emitting InGaN primary LED (LUXEON TM The converter structure is attached to an uncoated surface disposed on the LED.

[0174] Fig.21 The SWIR emission spectrum 2100 of the phosphor-converted LED formed in this example is shown. Fig.21 As can be seen in , the emission spectrum shows that the emission from the SWIR pcLED covers the spectral range of 1600-2130 nm. For the wavelength range of 1610-2130 nm, the minimum 2110 and average 2120 emission powers relative to the maximum emission power are greater than 10% and 35%, respectively.

[0175] Fig.22A and Fig. 22B The apparatus shown in was used to test the SWIRpcLED of Example 7 as a light source for the spectrum. Fig.22A and Fig. 22B In this example, the test device 2200 includes a SWIR pcLED formed in this example 2210, which includes a blue-emitting InGaN primary LED 1 with a wavelength conversion structure 2 having an attached dichroic coating 3 formed in Example 6. The SWIR pcLED 2210 is located near an IR spectrometer fiber 4. Fig. 22B The test sample (polystyrene) 5 is shown. The SWIR pcLED 2210 is placed The optical fiber of the FT-IR spectrometer 4 (Ocean Inside) was placed near (10-20 mm distance) and a reference spectrum was first recorded, and then the polystyrene test sample 5 was placed in the optical path (Figure 22). Fig.23 The FT-IR spectrum of a polystyrene test sample is shown.

[0176] Example 8

[0177] Example 8 describes the formation of a light source for spectroscopy, the light source comprising two different phosphors formed in two different wavelength conversion structures to extend the light source emission to shorter wavelengths. The light source of this example comprises two wavelength conversion structures: (1) a first wavelength conversion structure comprising a SWIR phosphor Gd disclosed herein; 2.32 Tm 0.18 Sc 1.5 Lu 0.3 Ga 1.81 Al 1.81 Cr 0.1 O 12 and (2) a second ceramic wavelength conversion structure comprising a garnet structure according to the description given in U.S. patent application Ser. No. 17 / 035,233, filed on Sept. 23, 2020, entitled “SWIR pcLED and Phosphor Emitting in the 1100-1700 nm Range,” having a composition of Gd3Ga 3.7 SCa 0.18 Ni 0.02 Zr 0.021 Cr 0.1 O 12 , and the lattice constant

[0178] The first wavelength conversion structure is formed to include a SWIR garnet phosphor component Gd 2.32 Tm 0.18 Sc 1.5 Lu 0.3 Ga 1.81 Al 1.81 Cr 0.1 O 12A ceramic plate of 100 μm was prepared using the process described for Example 5. For Example 8, 78.251 g of gadolinium oxide (Treibacher, 3N5), 19.451 g of scandium oxide (Treibacher, 4N), 11.114 g of lutetium oxide (Rhodia, 4N), 31.54 g of gallium oxide (Dowa Elecronics Materials, 4N), 1.41 g of chromium (III) oxide (Alfa Aesar, 99%), 17.17 g of aluminum oxide (Baikowski, SP-DBM), 6.445 g of thulium oxide (Treibacher, 4N) and 110 μL of tetraethyl orthosilicate (Merck, pa) were ground in ethanol until the average particle size reached 0.87 μm. After the forming and firing steps described for Example 5, the unit cell constant was obtained. Ceramic SWIR phosphor ceramics.

[0179] The second wavelength conversion structure is formed as described in U.S. Patent Application Serial No. 17 / 035,233, filed on September 23, 2020, entitled “SWIR pcLED and Phosphor Emitting in the 1100-1700nm Range”. 3.7 SCa 0.18 Ni 0.02 Zr 0.021 Cr 0.1 O 12 and Gd 2.32 Tm 0.18 Sc 1.5 Lu 0.3 Ga 1.81 Al 1.81 Cr 0.1 O 12 The first and second ceramic converter structures of the phosphor are mounted on a 440nm emitting LED primary light source to obtain a Fig.24 Spectral power distribution of the illumination system within the SWIR wavelength range 2400 is shown.

[0180] exist Fig.24 , the dashed line 2410 shows the Gd3Ga 3.7 SCa 0.1 8Ni 0.02 Zr 0.021 Cr 0.1 O 12 The spectral power distribution of the lighting system with only the Gd phosphor material excited by the blue emitting primary LED light source is shown in FIG. 2.32 Tm 0.18Sc 1.5 Lu 0.3 Ga 1.81 Al 1.81 Cr 0.1 O 12 Spectral power distribution of lighting systems based on phosphor materials.

[0181] Example 9

[0182] Composition: Gd3Ga 4.7 Al 0.18 Ni 0.02 Zr 0.021 Cr 0.1 O 12 Phosphor. 13.3 g of gallium oxide (Dowa Electronics, 4N), 0.129 g of gadolinium fluoride (Materion, 4N), 0.078 g of zirconium oxide (Daichi, DK-1U), 0.045 g of nickel oxide (Aldrich, 99%), 16.16 g of gadolinium oxide (Treibacher, 4N), 0.229 g of chromium (III) oxide (Materion, 2N) and 0.275 g of aluminum oxide (Baikowski, RC-SP DBM) were mixed in a planetary ball mill and fired at 1540°C for 8 hours in an air atmosphere. After grinding in a planetary ball mill, the powder was fired again at 1510°C for 8 hours. After grinding and washing the powder in dilute hydrochloric acid and water, the phosphor was dried at 300°C and sieved. The phosphor material crystallizes in a cubic garnet structure with a lattice constant of And the calculated density is 7.07 g / cm 3 .

[0183] Example 10

[0184] Composition: Gd 2.82 Tm 0.18 Ga 2.7 Al 2.2 Cr 0.1 O 1216.29 g of gadolinium oxide (Treibacher, 3N8), 8.28 g of gallium oxide (Dowa Electronics, 4N), 0.53 g of gadolinium fluoride (Materion, 4N), 1.138 g of thulium oxide (Treibacher, 4N), 0.25 g of chromium (III) oxide (Materion, 2N) and 3.674 g of aluminum oxide (Baikowski, RC-SPDBM) were mixed in a planetary ball mill and fired at 1550°C for 8 hours in an air atmosphere. After grinding and washing the powder in dilute hydrochloric acid and water, the phosphor was dried at 300°C and sieved. The phosphor material crystallized in a cubic garnet structure with a lattice constant of And the calculated density is 6.54 g / cm 3 .

[0185] Example 11

[0186] Phosphor-converted LEDs containing the phosphors of Examples 9 and 10. 1. One part of each phosphor of Examples 9 and 10 was mixed with one part of a two-component heat-curable methylphenyl silicone encapsulant (OE-7662, Dow Corning) and dispensed into a mid-power LED package equipped with a blue-emitting InGaN die, such as used in the commercial LUXEON ONYX product. After curing the silicone at 150°C, the LEDs were characterized at a constant current of 200 mA at different ambient temperatures.

[0187] Fig.25 The emission spectrum of the pcLED of Example 11 is shown (50° C. ambient T, 200 mA DC drive current). Fig.26 The variation in emission power of the pcLED of Example 11 in the wavelength ranges of 1644-1656 nm, 1714-1726 nm, and 1814-1826 nm is shown as a function of the ambient temperature.

[0188] Example 12

[0189] Phosphor-converted LEDs containing the phosphors of Examples 9 and 10. 1. One part of each phosphor of Examples 9 and 10 was mixed with one part of a two-component thermally curable polydimethylsiloxane encapsulant (OE-7340, Dow Corning) and dispensed into a mid-power LED package equipped with a blue-emitting InGaN die, such as used in the commercial LUXEON ONYX product. After curing the silicone at 150°C, the LEDs were characterized at a constant current of 200 mA at different ambient temperatures.

[0190] Fig. 27The emission spectrum of the pcLED of Example 12 is shown (50° C. ambient T, 200 mA DC drive current). Fig.28 The power variation of the pcLED of Example 12 in the wavelength ranges of 1644-1656 nm, 1714-1726 nm, and 1814-1826 nm is shown as a function of the ambient temperature.

[0191] Example 13

[0192] Phosphor-converted LEDs containing the phosphors of Example 9 and Example 10. 1.54 parts of the phosphor of Example 9 and 0.66 parts of the phosphor of Example 10 were mixed with one part of a two-component thermally curable polydimethylsiloxane encapsulant (OE-7340, Dow Corning) and dispensed into a mid-power LED package equipped with a blue-emitting InGaN die, such as used in the commercial LUXEON ONYX product. After curing the silicone at 150°C, the LEDs were characterized at a constant current of 200 mA at different ambient temperatures.

[0193] Fig.29 The emission spectrum of the pcLED of Example 13 is shown (50° C. ambient T, 200 mA DC drive current). Fig.30 The variation in emission power of the pcLED of Example 13 in the wavelength ranges of 1644-1656 nm, 1714-1726 nm, and 1814-1826 nm is shown as a function of the ambient temperature.

[0194] Example 14

[0195] Composition: Gd 2.82 Tm 0.18 Ga 2.7 Al 2.2 Cr 0.1 O 12Phosphor. 82.65 g of gadolinium oxide (Treibacher, 4N), 9.28 g of gadolinium oxide (superamic grade, Liyang Solvay), 45.44 g of gallium oxide (Dowa Electronics Materials, 4N), 1.366 g of chromium (III) oxide (Materion, 2N), 21.07 g of aluminum oxide (Baikowski, SP-DBM), 6.22 g of thulium oxide (Treibacher, 4N) and 0.043 g of fumed silica (OX-50, Evonik) were ball milled in ethanol to which 3.7 g of dispersant (MalialimAKM-0531) was added. After adding the plasticizer-polyvinyl butyral binder, the carrier ceramic tape was cast on a mylar film. After drying, the resulting film with a thickness of ~14 μm was further processed by means of stacking, lamination and cutting procedures to obtain a ceramic green body with a thickness in the range of 140-230 μm. The ceramic green body is sintered in an air atmosphere at a temperature range of 1480-1585°C.

[0196] Example 15

[0197] Composition: Gd3Ga 4.7 Al 0.26 Ni 0.02 Zr 0.021 Cr 0.1 O 12 Phosphor. 79.11 g of gadolinium oxide (Treibacher, 4N), 16.01 g of gadolinium oxide (superamic grade, Liyang Solvay), 76.91 g of gallium oxide (Dowa Electronics Materials, 4N), 1.327 g of chromium (III) oxide (Materion, 2N), 2.32 g of aluminum oxide (Baikowski, SP-DBM), 0.457 g of zirconium oxide (Daichi, DK-1U), 0.264 g of nickel oxide (Aldrich, 2N) and 0.042 g of fumed silica (OX-50, Evonik) were ball milled in ethanol to which 3.7 g of dispersant (Malialim AKM-0531) was added. After adding a plasticizer-polyvinyl butyral binder, the carrier ceramic tape was cast on a mylar film. After drying, the resulting film with a thickness of ~14 μm was further processed by means of stacking, laminating and cutting procedures to obtain ceramic green bodies with a thickness in the range of 140-230 μm. The ceramic green bodies were sintered in an air atmosphere at a temperature range of 1480-1550°C.

[0198] Example 16

[0199] A ceramic converter processed by stacking the ceramic sheets of Example 14 and Example 15. 14 ceramic tape sheets were stacked in the following order: 2 sheets of Example 14, 10 sheets of Example 15, and 2 sheets of Example 14. After lamination and cutting into ceramic green bodies with a thickness in the range of 195-200 μm, the layered composite converter structure was sintered in an air atmosphere at a temperature in the range of 1520-1580°C.

[0200] The following numbered clauses provide additional non-limiting aspects of the present disclosure.

[0201] 1. A luminescent material having a peak emission wavelength in the range of 1600-1900 nm, comprising Cr having the general formula 3+ and Tm 3+ Co-doped garnet phosphor: (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Sc d Al e ]{Ga 3-c Al c} 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0≤u≤2,0 <y≤1.5、0≤a≤1、0<b≤0.3、0≤c≤3、0≤d≤0.5、0≤e≤1.8。

[0202] 2. The luminescent material according to item 1, having the chemical formula Gd 2.82 Tm 0.18 Ga 2.7 Al 2.2 Cr 0.1 O 12 .

[0203] 3. A wavelength conversion structure comprising the luminescent material according to clause 1 in the form of a powder dispersed in a binder.

[0204] 4. A wavelength conversion structure according to clause 3, wherein the adhesive is or comprises a silicone material.

[0205] 5. A wavelength conversion structure according to clause 3, wherein the adhesive is or comprises methylphenyl silicone.

[0206] 6. A wavelength conversion structure according to clause 3, wherein the adhesive is or comprises polymethylsiloxane.

[0207] 7. A wavelength conversion structure comprising the luminescent material according to clause 1 in ceramic form.

[0208] 8. A phosphor-converted LED comprising the luminescent material according to clause 1 and a semiconductor light emitting diode.

[0209] 9. A luminescent material having a peak emission wavelength in the range of 1400-1600 nm, comprising Cr having the general formula 3+ and Ni 2+ Co-doped garnet phosphor: (Gd 3-u RE u )[Ga 2-a-b-d-e Ni a Cr b L d Al e ]{Ga 3-c Al c} 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0≤u≤2,0 <a≤0.1、0<b≤0.3、0≤c≤3、0<d≤0.15、0≤e≤2。

[0210] 10. The luminescent material according to item 9, having the chemical formula Gd3Ga 4.7 Al 0.18 Ni 0.02 Zr 0.021 Cr 0.1 O 12 .

[0211] 11. A wavelength conversion structure comprising the luminescent material according to clause 9 in powder form dispersed in a binder.

[0212] 12. A wavelength conversion structure according to clause 11, wherein the adhesive is or comprises a silicone material.

[0213] 13. A wavelength conversion structure according to clause 11, wherein the adhesive is or comprises methylphenyl silicone.

[0214] 14. A wavelength conversion structure according to clause 11, wherein the adhesive is or comprises polymethylsiloxane.

[0215] 15. A wavelength conversion structure comprising the luminescent material according to clause 9 in ceramic form.

[0216] 16. A phosphor converted LED comprising the luminescent material according to clause 9 and a semiconductor light emitting diode.

[0217] 17. A light emitting device, comprising:

[0218] The luminescent material according to clause 1;

[0219] A luminescent material according to clause 9; and

[0220] One or more semiconductor light emitting diodes arranged to stimulate luminescence from the luminescent material according to clause 1 and clause 9 to provide short wavelength infrared emission in the range of 1300-2000 nm.

[0221] 18. A light emitting device according to clause 17, wherein the emission intensity from the device at 1650 nm, 1720 nm and 1820 nm varies by less than 5% over an ambient temperature range of 0-100°C.

[0222] 19. A spectrometer comprising:

[0223] A light emitting device according to clause 17; and

[0224] A short wavelength infrared detector is arranged to detect the intensity of short wavelength infrared light emitted by the light emitting device and reflected by the sample.

[0225] 20. A smartphone comprising the spectrometer according to clause 19.

[0226] 21. A wearable device comprising a spectrometer according to clause 19.

[0227] 22. A handheld device comprising a spectrometer according to clause 19.

[0228] 23. A method of determining hydration and sebum levels in a skin sample, comprising measuring the reflectance spectrum at 1650 nm, 1720 nm and 1820 nm from the skin sample using a spectrometer according to clause 19.

[0229] The present disclosure is illustrative and not restrictive. Further modifications will be clear to those skilled in the art in view of the present disclosure and are intended to fall within the scope of the appended claims. For example, as described above, a light emitting device comprising a SWIR phosphor as disclosed herein in combination with a light source that emits a shorter wavelength pump light to excite emission from the SWIR phosphor may also include a dichroic optical device (e.g., a filter) that is positioned to reflect transmitted pump light that is not absorbed by the SWIR phosphor back into the SWIR phosphor. In addition, or alternatively, the light emitting device may include an additional phosphor in the form of a powder or ceramic that is positioned to convert transmitted pump light that is not absorbed by the SWIR phosphor into visible light (e.g., red light or green light). For example, the output from such a light emitting device may include white light (or visible light of another color) and SWIR light. For example, such a light emitting device may be used in or for use in a motor vehicle headlight.

Claims

1. A light emitting device, comprising: The first luminescent material having a peak emission wavelength in the range of 1600-1900 nm comprises Cr having the general formula 3+ and Tm 3+ Co-doped garnet phosphor: (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Sc d Al e ]{Ga 3-c Al c } 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0≤u≤2,0 <y≤1.5、0≤a≤1、0<b≤0.3、0≤c≤3、0≤d≤0.5,0≤e≤1.8; A second luminescent material having a peak emission wavelength in the range of 1400-1600 nm, comprising Cr having the general formula 3+ and Ni 2+ Co-doped garnet phosphor: (Gd 3-u RE u )[Ga 2-a-b-d-e Ni a Cr b L d Al e ]{Ga 3-c Al c } 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0≤u≤2,0 <a≤0.1、0<b≤0.3、0≤c≤3、0<d≤0.15,0≤e≤2; and One or more semiconductor light emitting diodes arranged to stimulate luminescence from the first luminescent material and the second luminescent material to provide short wavelength infrared emission in the range of 1300-2000 nm.

2. The light emitting device of claim 1, wherein the emission intensity at 1650 nm, 1720 nm and 1820 nm from the device varies by less than 5% over an ambient temperature range of 0-100°C. The light emitting device according to claim 1 , wherein the first light emitting material is in the form of a powder dispersed in a binder. The light emitting device according to claim 3 , wherein the adhesive is or includes a silicone material. The light emitting device according to claim 3 , wherein the adhesive is or includes methylphenyl silicone resin. The light emitting device according to claim 3 , wherein the adhesive is or includes polymethylsiloxane. The light emitting device according to claim 1 , wherein the first light emitting material is in the form of a ceramic.

8. The light emitting device according to claim 1, wherein the second light emitting material has a chemical formula of Gd3Ga 4.7 Al 0.18 Ni 0.02 Zr 0.021 Cr 0.1 O 12 .

9. The light emitting device according to claim 1, wherein the second light emitting material is in the form of a powder dispersed in a binder. 10 . The light emitting device according to claim 9 , wherein the adhesive is or includes a silicone material. The light emitting device according to claim 9 , wherein the adhesive is or includes methyl phenyl silicone resin. 12 . The light emitting device according to claim 9 , wherein the adhesive is or includes polymethylsiloxane.

13. The light emitting device of claim 1, wherein the second light emitting material is in the form of a ceramic.

14. A spectrometer comprising: The light emitting device according to any one of claims 1 to 13; and A short wavelength infrared detector is arranged to detect the intensity of the short wavelength infrared light emitted by the light emitting device and reflected by the sample.

15. A smart phone comprising the spectrometer according to claim 14.

16. A wearable device comprising the spectrometer according to claim 14.

17. A handheld device comprising the spectrometer according to claim 14.

18. A method of determining hydration and sebum levels in a skin sample comprising measuring the reflectance spectrum at 1650 nm, 1720 nm and 1820 nm from the skin sample using a spectrometer according to claim 14.

19. A luminescent material having a peak emission wavelength in the range of 1600-1900 nm, comprising Cr having the general formula 3+ and Tm 3+ Co-doped garnet phosphor: (Gd 3-u-y Tm y RE u )[Ga 2-a-b-d-e Lu a Cr b Sc d Al e ]{Ga 3-c Al c } 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Sc and 0≤u≤2,0 <y≤1.5、0≤a≤1、0<b≤0.3、0≤c≤3、0≤d≤0.5、0≤e≤1.8。 20. A luminescent material having a peak emission wavelength in the range of 1400-1600 nm, comprising Cr having the general formula 3+ and Ni 2+ Co-doped garnet phosphor: (Gd 3-u RE u )[Ga 2-a-b-d-e Ni a Cr b L d Al e ]{Ga 3-c Al c } 12 , where RE = La, Y, Yb, Nd, Ho, Er, Ce, Lu, Tm, Sc and L = Ti, Zr, Hf, Sn, Ge, Si and 0≤u≤2,0 <a≤0.1、0<b≤0.3、0≤c≤3、0<d≤0.15、0≤e≤2。

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