Light-emitting device using metasurface and light-emitting method thereof

Abstract

A light emitting device for promoting the growth of one or more plants. The device has a light emitting layer including one or more light emitting diodes for emitting light, and at least one light conversion layer including one or more light conversion units. Each light conversion unit has a metasurface for adjusting one or more parameters of the light emitted from the light emitting layer. In some embodiments, the light emitting device may also have a polarization control layer sandwiched between the light emitting layer and the light conversion layer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial Nos. 62 / 862,853 (filed June 18, 2019) and 62 / 961,317 (filed January 15, 2020), the contents of each of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to light emitting methods, devices and systems, and in particular to light emitting methods, devices and systems that use metasurfaces to control emitted light. Background Art

[0004] Light emitting diodes (LEDs) are well known and have been widely used in many industries, mainly as light indicators with low power consumption. In recent years, LEDs with increased power output or luminous intensity have been developed and used as lighting sources. For example, LED lights are replacing other types of lights in the market, such as incandescent lamps, compact fluorescent lamps (CFLs), etc., as they improve energy efficiency, safety, and reliability. Since daily lighting greatly increases the burden on the power grid and greatly increases the overall demand for power generation, the energy efficiency of LEDs will play a vital role in future energy conservation. Due to its superior energy efficiency, LEDs are likely to dominate the lighting market.

[0005] High-efficiency LEDs have replaced traditional lighting solutions in a variety of applications, such as flashlights, portable lamps, luminaires, streetlights, etc. LEDs can be powered by various types of power sources, such as batteries, conventional grid, renewable energy systems, and energy storage systems (such as those using photovoltaic (PV) panels and battery packs), thus providing a lot of flexibility in adapting lighting solutions to specific usage scenarios.

[0006] In many lighting solutions, it is preferred to configure a light source (e.g., an LED light source) to emit directional light, such as forming a converging light beam and focusing on a predefined area to obtain enhanced lighting intensity, forming a collimated light beam to reach a distant target, forming a divergent light beam to illuminate a large area, etc. In some lighting solutions, the light direction of the light source may preferably be adjustable. In the prior art, the light source usually uses a mirror or a reflective surface to form a directional light, and often uses a mechanical device to rotate the mirror or the reflective surface to adjust the direction of the light. Such directional lighting devices are usually large in size, slow in response, and low in efficiency.

[0007] LEDs with increased power output and / or increased luminous intensity are also used as light sources for growing plants and the like. Such LEDs are sometimes referred to as LED grow lights and offer various advantages, such as producing precise wavelengths of light, high intensity, high efficiency, etc. LED grow lights are also beneficial for growing plants indoors because the plant growing process can be conducted in a controlled environment with much less risk and other unwanted outdoor variables.

[0008] Plant growth is the result of a process called "photosynthesis." As is known in the art, the photosynthesis process uses energy from light to convert carbon dioxide (CO2) into organic materials. Specifically, light energy is absorbed by specialized proteins containing chlorophyll pigments that are found in the membranes of photosynthetic cells called chloroplasts. Photosynthetic cells are primarily found in plant leaves.

[0009] However, chlorophyll absorbs energy only from specific parts of the light spectrum, or colors. The effective light spectrum spans the blue and red spectrum. The green part of the spectrum is reflected, which is why plant leaves are usually green. When the photosynthetic cells in the leaves die and the chlorophyll degrades, other pigment molecules in the leaves control the light reflection while they are degraded to the point where they appear only brown.

[0010] This shows that different pigments in chloroplasts absorb specific wavelengths of light to promote photosynthesis, and that the photosynthetic efficiency or rate is strongly correlated with the light spectrum.

[0011] For example, rice plants grown under blue and red light have higher photosynthesis efficiency than plants grown only under red light. Pea leaves grown under red LED light contain more beta-carotene than pea leaves grown under blue-white LED light.

[0012] Light intensity is another factor affecting photosynthesis, as photosynthetic organisms respond to high light intensity to reduce stress effects. Under red LED light, wheat seedlings at 100 μmol m -2 s -1 Chlorophyll accumulation was observed at 500 μmol m -2 s -1 Chlorophyll is not accumulated.

[0013] It has been observed that plants generally absorb the blue light spectrum during early growth, and then gradually absorb the red light spectrum during maturity and flowering stages. It has also been observed that some plants have a highly ordered composition that makes their interaction with light polarization sensitive. For example, such a plant may absorb or reflect light with a specific polarization state more efficiently than light with other polarization states.

[0014] Furthermore, plants are able to sense the duration of photoperiods and timings and change their growth rates accordingly.

[0015] Plant cultivation using a constant or universally defined light configuration is neither energy-efficient nor suitable for photosynthesis. Since the prior art LED grow lights generally provide light to plants without considering the above factors, they cannot provide an optimized lighting configuration for optimizing the physiological processes of growing plants. In addition, different plants require different light characteristics (e.g., intensity, spectrum, polarization, time, etc.) to achieve optimal growth performance. However, the prior art LED grow lights cannot adapt to the needs of plants and cannot provide appropriate light characteristics.

[0016] For example, traditional lighting systems, such as LED panels for indoor plant growth, usually do not produce an even distribution of light on the plants. Their intensity is usually strongest in the center and gradually decreases away from the center.

[0017] FIG. 1A shows a conventional light source 10 that emits a light beam 12 toward a square image plane 14 at a distance from the square image plane 14. FIG. 1B shows a light intensity distribution 16 on the image plane 14. It can be seen that the conventional light source 10 does not produce a uniform distribution of light on the image plane 14. Instead, the light intensity distribution 16 on the image plane 14 is strongest at its center and gradually decreases away from the center. In addition, the intensity light distribution 16 is symmetrical about the point of incidence of the light beam 12 on the image plane 14.

[0018] 2A and 2B show the LED panel 10 obtained using ray tracing at a distance of about 3 meters (m) from the panel 10 in a 6×6 square meter (m2) area. 2 ) The resulting illumination pattern in the image plane 14. The intensity distribution is clearly non-uniform.

[0019] Therefore, using a grow light that provides sufficient light at the periphery of the plant will result in over-illumination of the center of the plant, resulting in poor plant growth. On the other hand, providing sufficient light at the center of the plant will result in inefficient illumination of the periphery of the plant, also resulting in poor plant growth. Such intensity distribution is due to the symmetry of the center of the image plane relative to the light emitter.

[0020] Such a light source 10 may not be desirable in other applications. For example, a street lamp using such a light source 10 may result in glare and overall inefficient lighting.

[0021] LEDs are also used in indoor and outdoor displays that also require careful control of various light characteristics such as intensity, polarization, timing, and / or the like with rapid response.

[0022] Therefore, LED devices, systems, and methods having controlled light characteristics remain desirable. Summary of the invention

[0023] According to one aspect of the present disclosure, a light emitting device is provided, comprising: a light emitting layer for emitting light; and a light conversion layer coupled to the light emitting layer, the light conversion layer comprising one or more light conversion units, each light conversion unit comprising a metasurface for adjusting one or more parameters of light emitted from the light emitting layer.

[0024] In some embodiments, the light emitting layer includes one or more light emitting diodes (LEDs) for emitting light.

[0025] In some embodiments, the light conversion layer is printed onto the light emitting layer.

[0026] In some embodiments, the light-emitting layer includes one or more light-emitting units; the light-converting layer includes a shell having one or more containers for receiving one or more metasurfaces; and the one or more containers are located at positions corresponding to the positions of the one or more light-emitting units, for aligning the one or more metasurfaces with the one or more light-emitting units.

[0027] In some embodiments, each of the one or more containers includes an inner surface expanding outwardly, the inner surface having an inner opening for receiving light emitted from the light-emitting layer and an outer opening for passing the received light, the area of ​​the outer opening being larger than the area of ​​the inner opening.

[0028] In some embodiments, the interior surface of each of the one or more containers is reflective.

[0029] In some embodiments, the inner surface of each of the one or more containers has a parabolic shape in cross-section.

[0030] According to one aspect of the present disclosure, a light emitting device is provided, comprising: a light emitting layer for emitting light; and a light conversion layer comprising one or more light conversion units, each light conversion unit comprising a metasurface, at least one metasurface being polarization selective, for selectively allowing light having a predefined polarization state emitted from the light emitting layer to pass through.

[0031] In some embodiments, each of the one or more metasurfaces includes a plurality of nanoscale structures arranged in an asymmetric base geometry.

[0032] In some embodiments, the light emitting device further includes a polarization control layer sandwiched between the light emitting layer and the light conversion layer for polarizing light emitted from the light emitting layer.

[0033] In some embodiments, the light emitting device is a grow light for promoting the growth of one or more plants.

[0034] According to one aspect of the present invention, a light emitting device for promoting the growth of one or more plants is provided. The light emitting device comprises: a light emitting layer for emitting light; and at least one light conversion layer comprising one or more light conversion units, each light conversion unit comprising a metasurface for adjusting one or more parameters of light emitted from the light emitting layer, for optimizing the lighting configuration of one or more plants.

[0035] According to one aspect of the present disclosure, a display device is provided. The display device includes: a light-emitting layer for emitting light; and at least one light conversion layer including one or more light conversion units, each light conversion unit including a metasurface for adjusting one or more parameters of light emitted from the light-emitting layer, for displaying one or more images.

[0036] According to one aspect of the present disclosure, a light emitting device is provided. The light emitting device includes: a light emitting layer for emitting light; a polarization control layer coupled to the light emitting layer for polarizing the light emitted from the light emitting layer; and at least one light conversion layer coupled to the polarization control layer, wherein the at least one light conversion layer includes one or more light conversion units, each light conversion unit includes at least one metasurface, and the at least one metasurface is polarization selective and is used to selectively allow polarized light from the polarization control layer to pass through so as to switch between different illumination patterns or images.

[0037] According to one aspect of the present disclosure, a light emitting device is provided. The light emitting device includes: a light emitting layer for emitting light; a polarization control layer coupled to the light emitting layer for polarizing the light emitted from the light emitting layer; and at least one light conversion layer coupled to the polarization control layer, wherein the at least one light conversion layer includes one or more light conversion units, each light conversion unit includes at least one metasurface, and the at least one metasurface is polarization selective and is used to selectively allow polarized light from the polarization control layer to pass through so as to generate a plurality of different illumination patterns or images at different locations.

[0038] According to one aspect of the present disclosure, a light emitting device is provided. The light emitting device includes: a light emitting layer for emitting light to a source field of view (FOV); and at least one metasurface layer in front of the light emitting layer for directing light emitted from the light emitting layer to a first FOV having an angular span smaller than an angular span of the source FOV.

[0039] In some embodiments, the light emitting device further comprises a polarization control layer sandwiched between the light emitting layer and at least one light conversion layer; the polarization control layer is configured to polarize light emitted from the light emitting layer to a first polarization state or a second polarization state in response to a control signal; and wherein at least one light conversion layer is configured to direct light from the polarization control layer in the first polarization state to a first FOV having an angular span smaller than an angular span of a source FOV, and to direct light from the polarization control layer in the second polarization state to a second FOV having an angular span larger than an angular span of the first FOV.

[0040] According to one aspect of the present disclosure, a light emitting device is provided, which includes: a light emitting layer for emitting light; and a light conversion layer in front of the light emitting layer, the light conversion layer including a plurality of light conversion units, each light conversion unit including a metasurface for directing light emitted from the light emitting layer to a target area to form a predefined light distribution pattern.

[0041] In some embodiments, the predefined light distribution pattern is a substantially uniform distribution of light energy over the target area.

[0042] In some embodiments, the plurality of metasurfaces include a first group of metasurfaces for directing light emitted from the light-emitting layer toward a boundary of a target area, and a second group of metasurfaces for directing light emitted from the light-emitting layer toward a center of the target area, for producing a substantially uniform distribution of light energy over the target area.

[0043] According to one aspect of the present invention, a solar energy collection device is provided. The solar energy collection device comprises: a photovoltaic layer having a plurality of photovoltaic cells; and at least one metasurface layer in front of the photovoltaic layer for guiding light to the photovoltaic layer without substantially causing reflection on the photovoltaic layer.

[0044] In some embodiments, the solar energy collection device includes multiple metasurface layers for guiding light within a predetermined range of incident angles to be perpendicularly incident to the photovoltaic layer.

[0045] According to one aspect of the present disclosure, a light emitting device is provided. The light emitting device includes: a light emitting layer for emitting light; and at least one metasurface layer in front of the light emitting layer for directing light emitted from the light emitting layer in a first polarization state to a first FOV, and directing light emitted from the light emitting layer in a second polarization state to a second FOV; the first and second FOVs overlap and are laterally offset from each other so as to form a three-dimensional (3D) perception for a user wearing a pair of glasses with lenses of different polarization states.

[0046] According to one aspect of the present disclosure, a light emitting device is provided. The light emitting device includes: a light emitting layer for emitting light; and at least one metasurface layer in front of the light emitting layer for directing light from the light emitting layer in a first polarization state to a first FOV, and directing light from the light emitting layer in a second polarization state to a second FOV; the first and second fields of view are laterally offset from each other, so that the first FOV is visible to a first eye of a user only at a predetermined distance, and the second FOV is visible to a second eye of the user only at a predetermined distance, so as to enable the user to form a 3D perception. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG1A is a schematic diagram showing a prior art light source emitting a light beam toward a square image plane at a certain distance from the square image plane;

[0048] FIG. 1B shows the light intensity distribution on an image plane of light emitted from the prior art light source shown in FIG. 1A ;

[0049] FIG. 2A is a schematic diagram showing a prior art light emitting diode (LED) panel that emits a light beam toward a square image plane at a certain distance from the square image plane;

[0050] FIG2B shows an illumination pattern of light emitted from a prior art LED panel on an image plane, the illumination pattern being obtained using ray tracing;

[0051] Figure 3 is a schematic diagram showing the structure of a light emitting device according to some embodiments of the present disclosure, the light emitting device comprising an LED light emitting layer and a light conversion layer having one or more metasurfaces;

[0052] Figure 4 yes Figure 3 A schematic exploded view of the light emitting device shown;

[0053] Figure 5 Show Figure 3 The light conversion unit of the light conversion layer of the light emitting device shown;

[0054] Figure 6 Shown for forming Figure 5 An example of the structure of the metasurface of the light conversion unit shown;

[0055] Figure 7 is a schematic exploded view of a light emitting device according to some embodiments of the present disclosure, the light emitting device comprising an LED light emitting layer, a polarization control layer, and a metasurface light conversion layer;

[0056] Fig. 8A is a diagram showing some embodiments of the present disclosure Figure 7 A schematic diagram of a pixel of a polarization control layer of an optical device shown;

[0057] Figure 8B It is shown Figure 7 The pixels of the light conversion layer of the optical device shown correspond to Fig. 8A A schematic diagram of a pixel of the polarization control layer shown;

[0058] Fig. 9A The present invention shows some other embodiments of the present invention. Figure 7 A schematic diagram of a pixel of a polarization control layer of an optical device shown;

[0059] Fig. 9B It is shown Figure 7 The pixels of the light conversion layer of the optical device shown correspond to Fig. 9A A schematic diagram of a pixel of the polarization control layer shown;

[0060] Fig. 10A The present invention shows some other embodiments of the present invention. Figure 7 A schematic diagram of a pixel of a polarization control layer of an optical device shown;

[0061] Fig. 10B It is shown Figure 7 The pixels of the light conversion layer of the optical device shown correspond to Fig. 10A A schematic diagram of a pixel of the polarization control layer shown;

[0062] Fig.11A and 11B It shows that according to Fig. 8A and Figure 8B or Fig. 9A and Fig. 9B The embodiment shown Figure 7 A schematic diagram of an optical device showing two images in two directions;

[0063] Fig.12 It shows that according to Fig. 8A and Figure 8B , Fig. 9A and Fig. 9B or Fig. 10A and Fig. 10B The embodiment shown Figure 7 A schematic diagram of an optical device showing two images in two directions;

[0064] Fig.13 is a schematic exploded view of a light emitting device having a plurality of fiber optic cables according to some embodiments of the present disclosure;

[0065] Fig.14 It is shown Figure 3 Conceptual diagram of printing of a light conversion layer of a light emitting device shown;

[0066] Fig.15 is a schematic diagram of a lighting system for promoting plant growth according to some embodiments of the present disclosure;

[0067] Fig.16 is a schematic diagram of a lighting system for promoting plant growth, according to some embodiments of the present disclosure, the lighting system includes a sensor for monitoring plant growth;

[0068] Fig.17 It is shown in Figure 3 A schematic diagram of the structure of a solar cell layer combined in the light emitting device shown;

[0069] Fig.18 is a schematic diagram showing the structure of a lighting system used as a lighting or light source with a controlled lighting pattern according to some embodiments of the present disclosure;

[0070] Fig.19 Shown is formed by Fig.18 An example of a cost function for a lighting system to generate a lighting pattern is shown;

[0071] Fig. 20 It is shown by Fig.18 A flowchart of the steps of a process performed by the processing structure of the lighting system shown to find the global (or near-global) minimum of a cost function using a gradient descent method;

[0072] Figures 21 to 25 Show Fig. 20 Optimization results of the process for producing various lighting patterns are shown;

[0073] Fig.26 is a schematic diagram showing the structure of a lighting system used as a lighting or light source with a controlled lighting pattern according to some embodiments of the present disclosure;

[0074] Fig.27A is a schematic diagram showing a splitting metasurface for generating an intensity distribution boundary in an image plane;

[0075] Fig.27B Shown by Fig.27A The illustrated vertically split metasurface generates an illumination pattern in the image plane in which light energy is substantially concentrated along the vertical boundaries of the target area;

[0076] Fig.27C Shown by Fig.27A The illustrated horizontally split metasurface generates an illumination pattern in the image plane, wherein the light energy is substantially concentrated along the horizontal boundaries of the target area;

[0077] Fig.28 Show use Fig.27A Conceptual representation of the substantially concentrated light distribution along the horizontal and vertical boundaries of the target area for the horizontal and vertical split metasurfaces shown;

[0078] Fig.29A is a schematic diagram showing a converging metasurface for producing a light distribution substantially concentrated at the center of an image plane;

[0079] Fig.29B Shown by Fig.29A Illumination pattern in the image plane generated by the converging metasurface shown;

[0080] Fig.30 Shown in Fig.27A and 29A Conceptual representation of substantially uniform light distribution on the image plane generated by the splitting and converging metasurface shown;

[0081] Fig.31 shows substantially uniform light distribution on the image plane at different distances;

[0082] Fig.32 An exemplary implementation of a topological vector control panel (TVCP) using a metasurface array according to some embodiments of the present disclosure is shown, the TVCP comprising a metasurface housing coupled to a light emitting layer, the metasurface housing comprising a plurality of containers receiving a plurality of metasurface units therein;

[0083] Fig.33 is shown coupled to Fig.32 Photograph of the metasurface shell of the light-emitting layer of the TVCP shown;

[0084] Fig.34 Nanoscale structures of metasurfaces with asymmetric base geometry are shown for illuminating plants with specific polarization states;

[0085] FIG35 is a schematic diagram showing light reflection occurring on the surface of a photovoltaic cell of the prior art;

[0086] Fig.36 is a schematic diagram showing a solar panel device having a metasurface-based geocentric vector control panel (TVCP) in front of a photovoltaic panel for reducing light reflection at a surface of the photovoltaic panel;

[0087] Fig.37 is a schematic diagram showing a solar panel device having a metasurface-based TVCP in front of a photovoltaic panel for reducing the size of the photovoltaic panel;

[0088] FIG. 38 is a schematic diagram showing a prior art solar panel device having a photovoltaic panel without a TVCP for use with Fig.37 The solar panel installation shown is compared;

[0089] FIG39 is a schematic diagram showing a prior art display having a field of view (FOV) with a wide angular span;

[0090] Fig.40 is a schematic diagram showing a super-directional screen or display using a metasurface according to some embodiments of the present disclosure;

[0091] Fig.41 is a schematic diagram illustrating a variable field of view (VFOV) screen or display according to some embodiments of the present disclosure;

[0092] Fig.42 is a schematic diagram showing a VFOV screen or display according to some other embodiments of the present disclosure;

[0093] Figures 43A to 43G Show use Fig.42An example of a VFOV screen showing two images simultaneously, wherein a first image is displayed in a first FOV having a wide angular span, and a second image is displayed in a second FOV having a narrow angular span, such that the second image is not visible to a user located only in the first FOV;

[0094] Fig.44 is a schematic diagram showing a three-dimensional (3D) display of a metasurface viewable using glasses with polarized lenses according to some embodiments of the present disclosure;

[0095] Fig.45 is a schematic diagram showing a 3D display using a metasurface viewable without any glasses with polarized lenses according to some embodiments of the present disclosure;

[0096] 46 and 47 are schematic diagrams showing prior art solar panels having light reflection problems; and

[0097] Fig.48 and 49 is a schematic diagram showing a solar panel using a metasurface for mitigating or eliminating light reflection issues according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0098] Light-emitting device having a light-emitting layer and a light conversion layer

[0099] Now turn to Figure 3 and 4 According to some embodiments of the present disclosure, a light emitting device (also referred to as a "lighting device" or a "light device") is shown and generally identified using reference numeral 100. Here, the light emitting device may be a device for lighting, a device for promoting plant growth, or a device for displaying an image or video thereon.

[0100] The light emitting device 100 in these embodiments includes a light emitting layer 104 sandwiched between a substrate 102 and a light conversion layer 106 for emitting light 108 from the light emitting layer 104 through the light conversion layer 106. When the emitted light 108 passes through the light conversion layer 106, the light conversion layer 106 modulates one or more parameters of the light 108, such as amplitude or intensity, phase, polarization, pattern, direction, etc.

[0101] The light emitting layer 104 may be any suitable lighting device. In these embodiments, the light emitting layer 104 is printed, coated, or otherwise coupled to the substrate 102 and includes a plurality of light emitting diodes (LEDs) 110 arranged in a matrix, although other arrangements of the LEDs 110 are also readily available. Here, the LEDs 110 may be any suitable LEDs, such as conventional LEDs, quantum dot (QD) LEDs, organic LEDs (OLEDs), and / or the like.

[0102] The light conversion layer 106 is printed, coated, or otherwise coupled to the light emitting layer 104 for adjusting or otherwise converting parameters of the light emitted from the light emitting layer 104 (described in more detail later).

[0103] The light conversion layer 106 includes one or more light conversion units 122 arranged in a predefined pattern, wherein each light conversion unit 122 includes a metasurface. Here, a metasurface is a two-dimensional array of nanostructures with subwavelength spacing and can be used to modulate electromagnetic waves. The details of the metasurface are described in an academic paper entitled "Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction", by Nouthfang Yu, Patrice Genevet, Mikhail A. Kats, Francesco Aieta, Jean-Philippe Tetienne, Federico Capasso and Zeno Gaburro, Science, Vol. 334, No. 6054, pp. 333-337 (2011).

[0104] like Figure 5 and Figure 6 As shown, each metasurface unit 122 includes a metasurface having a subwavelength thickness (i.e., a thickness less than the wavelength of light emitted from the light-emitting layer 104), and includes a plurality of nanoscale structures 124 arranged in a periodic manner in a specific order for precisely adjusting or transforming the characteristics or parameters (e.g., amplitude or intensity, phase, polarization, pattern, direction, etc.) of the incident light, thereby allowing precise control of the properties of the light output therefrom.

[0105] In some embodiments, nanoscale structures 124 (also referred to as "nanostructures") may be sub-wavelength structures made of suitable metal or dielectric materials, one or more dimensions of which are smaller than the wavelength of light emitted from light emitting layer 104. In some embodiments, nanoscale structures 124 may include a plurality of nanorods (also referred to as "antennas"; see Figure 6 ). In some embodiments, the nanoscale structures 124 may include a plurality of V-shaped nanorods. As described above, the nanoscale structures 124 form a periodic or repeating pattern, and each pattern may include a plurality of nanoscale structures 124 having different shapes and sizes.

[0106] Depending on the geometry and distribution of nanostructures 124 , light transforming layer 106 may be configured to adjust or transform one or more parameters of incident light.

[0107] For example, Figure 4As shown, the metasurface unit 122A of the light transforming layer 106 may be configured to phase transform the incident light 108A and modify its converging direction, thereby forming a converging light beam focused at a desired point spaced apart from the light transforming layer 106 .

[0108] As another example, the metasurface unit 122B of the light transforming layer 106 may be configured to phase transform the incident light 108B and modify its collimation direction to form a collimated light beam for reaching a distant target.

[0109] As a further example, the metasurface unit 122C of the light transforming layer 106 may be configured to phase transform the incident light 108C and modify its divergence direction, thereby forming a divergent light beam for illuminating a large area.

[0110] In conventional grow light applications, one or more lighting devices (also referred to as grow light devices) are used to emit light to plants to promote their growth. In these applications, due to the divergent nature of the light beam, a portion of the light emitted from the grow light device (e.g., light emitted from a peripheral area of ​​the grow light device) may only partially illuminate the plants, thereby wasting light energy. Such a problem may be more significant if the plants are spaced apart from each other.

[0111] In some embodiments, the light emitting device 100 can be used as a grow light device without or at least reducing the above-mentioned problems. In these embodiments, the light conversion layer 106 or at least some of its metasurface units 122 can be designed to modify the direction of the incident light 108 toward the plant. For example, the light conversion layer 106 can be designed to adjust the light emitted from the peripheral area of ​​the light emitting layer 104 toward the plant, while making the light emitted from the central area of ​​the light emitting layer 104 more divergent to cover more areas of the plant, thereby producing significantly more efficient lighting.

[0112] In some embodiments, the light conversion layer 106 or at least some of its metasurface units 122 can be designed to adjust the parameters of the light emitted from the light emitting layer 104 to optimize the lighting configuration of the plants and adapt to their growth needs.

[0113] In some embodiments, the light conversion layer 106 or at least some of its metasurface units 122 can be designed to adjust the light emitted from the light emitting layer 104 toward a desired direction to form an area with high or low light concentration, thereby generating a hot spot or a cold spot at the target illumination area. Such a hot spot or a cold spot can be used to treat a damaged area of ​​a plant or to illuminate its fragile parts.

[0114] Figure 7 is a schematic exploded view of a light emitting device 200 according to some embodiments of the present disclosure. In these embodiments, the light emitting device 200 is similar to Figure 3 and Figure 4The light emitting device 100 in the illustrated embodiment is different in that the light emitting device 200 further includes a polarization control layer 202 sandwiched between the light emitting layer 104 and the light conversion layer 106 .

[0115] Furthermore, in these embodiments, the light conversion layer 106 can be polarization selective. In particular, each metasurface unit 122 can select a specific polarization, i.e., only allow light with a specific polarization state to pass therethrough and block light with other polarization states. Depending on the implementation, different metasurface units 122 of the light conversion layer 106 can have the same or different polarization selectivity settings.

[0116] The polarization control layer 202 is made of a suitable material that polarizes the incident light when it passes through the material (by Figure 7 In some embodiments, the polarization control layer 202 may form a single polarization control unit and polarize the incident light into a predetermined polarization state.

[0117] In some other embodiments, the polarization control layer 202 may form a single polarization control unit and include liquid crystals with voltage-controlled retardation. Therefore, the polarization of the polarization control layer 202 may be controlled by adjusting the voltage applied to the polarization control layer 202.

[0118] In some further embodiments, the polarization control layer 202 may include a plurality of polarization control units (not shown) corresponding to the plurality of metasurface units 122 of the light conversion layer 106. At least some of the polarization control units may be made of liquid crystals, and their polarization may be controlled by adjusting the voltage applied thereto.

[0119] Thus, the light conversion layer 106 exhibits a selective response to light of different polarization states. In some embodiments, the light emitting device 200 can be used as a display that can quickly switch between displaying different images without adjusting the light source (e.g., the light emitting layer 102). The switching display or illumination pattern can be encoded into the polarization pattern of the light conversion layer 106 and / or its voltage pattern for automatic pattern switching.

[0120] For example, in some embodiments, the light emitting device 200 may be used as a display, and its polarization control layer 202 and light conversion layer 106 may each include a plurality of units, forming corresponding pixels 232 and 234, respectively, each pixel including one or more sub-pixels (see Figures 8A to 10B ).

[0121] exist Fig. 8A and Figure 8BIn one embodiment shown, each pixel 232 of the polarization control layer 202 includes a plurality of sub-pixels (e.g., two sub-pixels 242A and 242B). Thus, the polarization control layer 202 includes a plurality of sub-pixel groups (also identified using reference numerals 242A and 242B), each group including a corresponding sub-pixel 242A or 242B for each pixel 232. Each sub-pixel group is configured for a particular polarization setting (see Fig. 8A ).

[0122] like Figure 8B As shown, each pixel 234 of the light transforming layer 106 has a metasurface sub-pixel (also indicated by reference numeral 234) that is controlled to switch between two polarization-selective and phase-transforming settings (indicated by symbol 246).

[0123] During operation, the light emitting layer 104 emits light (not shown). Through appropriate polarization settings, each sub-pixel group of the polarization control layer 202 adjusts the light emitted from the light emitting layer 104 and forms two light beams (not shown) with different polarization states. The two light beams overlap and are incident on the light conversion layer 106.

[0124] The metasurface sub-pixels 234 of the light transforming layer 106 are controlled to switch between two polarization selectivity and phase transforming settings 246, the first polarization selectivity setting being adapted to allow light beams from the first sub-pixel group 242A to pass therethrough, and the second polarization selectivity setting being adapted to allow light beams from the second sub-pixel group 242B to pass therethrough. Thus, the light emitting device 200 displays two images 222 and 224 alternately in two directions (see Fig.11A and 11B ). Depending on the phase shift settings, the two directions can be as follows Fig.11A and 11B Two different directions are shown, or they can be the same direction.

[0125] The switching of the polarization selectivity and phase shift settings of the light transforming layer 106 (also denoted as a refresh rate) can alternately display the two images 222 and 224 in a touchable manner at a slow rate or frequency, such as displaying the first image 222 at a first position for a few seconds and then displaying the second image 224 at a second position for another few seconds ( Fig.11A and 11B Alternatively, the refresh rate of the light transform layer 106 can be high frequency (eg, greater than or equal to 60 frames per second) so that the two images 222 and 224 are effectively displayed simultaneously at two locations of the human eye (see Fig.12 ).

[0126] exist Fig. 9A and 9BIn one embodiment shown, each pixel 232 of the polarization control layer 202 has a metasurface sub-pixel (also indicated by reference numeral 232) that is controlled to switch between two polarization settings (see Fig. 9A , represented by symbol 248).

[0127] like Fig. 9B As shown, each pixel 234 of light transform layer 106 includes a plurality of sub-pixels (e.g., two sub-pixels 244A and 244B). Thus, light transform layer 106 includes a plurality of sub-pixel groups (also identified using reference numerals 244A and 244B), each group including a corresponding sub-pixel 244A or 244B for each pixel 234. Each sub-pixel group is configured for a specific polarization selectivity and phase transform setting.

[0128] During operation, the light emitting layer 104 emits light (not shown). The polarization control layer 202 adjusts the light emitted from the light emitting layer 104 and forms a light beam (not shown) with a switched polarization state so as to pass through the first sub-pixel group 244A of the light conversion layer 106 or through the second sub-pixel group 244B of the light conversion layer 106. Depending on the refresh rate of the light conversion layer 106, the light emitting device 200 can alternately display two images 222 and 224 to the human eye in a touchable manner or effectively at the same time at two locations (see Fig.11A , 11B and 12).

[0129] exist Fig. 10A and 10B In one embodiment shown, each pixel 232 of the polarization control layer 202 includes a plurality of sub-pixels (e.g., two sub-pixels 242A and 242B). Thus, the polarization control layer 202 includes a plurality of sub-pixel groups (also identified using reference numerals 242A and 242B), each group including a corresponding sub-pixel 242A or 242B for each pixel 232. Each sub-pixel group is configured for a particular polarization setting (see Fig. 10A ).

[0130] Accordingly, if Fig. 10B As shown, each pixel 234 of the light conversion layer 106 includes a plurality of sub-pixels (e.g., two sub-pixels 244A and 244B). Thus, the light conversion layer 106 includes a plurality of sub-pixel groups (also identified using reference numerals 244A and 244B), each group including a corresponding sub-pixel 244A or 244B for each pixel 234. Each sub-pixel group is configured for a particular polarization selectivity and phase shift setting. The polarization selectivity setting of each sub-pixel group 244A or 244B matches the polarization setting of each sub-pixel group 242A or 242B (i.e., allowing light from the corresponding sub-pixel 242A or 242B to pass therethrough).

[0131] During operation, the light emitting layer 104 emits light (not shown). Each sub-pixel group 242A or 242B of the polarization control layer 202 adjusts the light emitted from the light emitting layer 104 and forms two light beams (not shown) with different polarization states. The two light beams overlap and are incident on the light conversion layer 106. Each light beam from the polarization control layer 202 passes through the corresponding sub-pixel group 244A or 244B of the light conversion layer 106, thereby forming two images 222 and 224 in two directions at the same time (see Fig.12 ).

[0132] In some embodiments, the light emitting device 200 can be used as a lighting device that can quickly switch between different lighting patterns. In addition, the light emitting device 200 can be used as a grow light device with a customized polarization pattern that is suitable for plants with highly ordered components that are sensitive to light polarization. For example, some plants may absorb or reflect light with a specific polarization state more effectively than light with other polarization states. Therefore, the light emitting device 200 can be used as a grow light device with a customized polarization pattern that is suitable for the needs of the plants to optimize their photosynthesis process. The structure of the lighting device 200 in various embodiments can be similar to Figures 8A to 10B The structure shown.

[0133] By using a metasurface in the light conversion layer 106, the lighting device disclosed herein can effectively couple light energy into a fiber optic cable. For example, Fig.13 is a schematic exploded view of a light emitting device 300 according to some embodiments of the present disclosure. In these embodiments, the light emitting device 300 is similar to Figure 3 and 4 The light emitting device 100 in the illustrated embodiment further includes a plurality of optical fiber cables 302 adjacent to each metasurface unit 122. Each metasurface unit 122 is configured to form a converging light beam incident into the corresponding optical fiber cable 302. Such a lighting device 300 can be used in various applications, such as efficient indoor lighting, local optimized lighting of plants, and efficient distribution of light energy over a target area.

[0134] Despite Fig.13 In the illustrated embodiment, light emitting device 300 is similar to light emitting device 100 (ie, having three layers 102, 104, and 106), and in some embodiments, light emitting device 300 may be similar to light emitting device 200 (ie, having four layers 102, 104, 202, and 106).

[0135] In the above embodiments, the lighting device 100, 200, or 300 includes only one light conversion layer 106. In some embodiments, the lighting device may include multiple light conversion layers 106. In some embodiments, at least some of the multiple light conversion layers 106 may be polarization selective, and different light conversion layers 106 may have the same or different polarization selectivity settings, depending on the implementation.

[0136] As described above, the various layers of light emitting device 100, such as light conversion layer 106, may be printed onto substrate 102 or onto each other using any suitable printing technique.

[0137] For example, Fig.14 is a conceptual diagram illustrating the printing of some layers such as light conversion layer 106 and light emitting layer 104 in some embodiments.

[0138] As shown, the substrate 102 (on which the light-emitting layer 104 is printed or otherwise coupled) is arranged on a flat surface of a platform 342. A printing device (not shown) having a slot die 344 is used to print the sub-layer / layer. The slot die 344 includes a corresponding ink cartridge 346 filled and moves (indicated by arrow 348) on the substrate 102 (or in particular the printed light-emitting layer 104) to deposit the metasurface material from the ink cartridge 346 thereto to form one or more metasurface light-conversion units 122.

[0139] Here, "ink" refers to a sub-layer / layer material in a suitable form, such as a solution, gel or powder, which is used as a precursor for manufacturing a layer. During the slot die manufacturing process of each layer, heat treatment is usually used to evaporate the solvent or melt the powder to solidify the manufactured layer.

[0140] Fig.15 4 is a schematic diagram of a lighting system 400 for promoting the growth of one or more plants 410 according to some embodiments of the present disclosure. As shown in the figure, the system 400 includes a power supply 402 for powering a control circuit 404 and a light emitting device 406, which can be any of the above-mentioned light emitting devices 100, 200 or 300. The control circuit 404 controls the light emitting device 406 to emit light 408 with customized parameters for illuminating the plant 410 to promote its growth.

[0141] Fig.16 is a schematic diagram of a lighting system 500 for promoting plant growth according to some embodiments of the present disclosure. The lighting system 500 in these embodiments is similar to Fig.14The lighting system 400 is shown and also includes a sensor 412 for monitoring the growth of the plant 410, such as a light sensor for monitoring light 414 reflected from the plant 410, and providing feedback to the control circuit 404 for adjusting light parameters as described above to optimize the lighting configuration to better promote the growth of the plant 410.

[0142] In some embodiments, the light emitting layer 104 can be a transparent LED layer, and the light emitting device 100, 200 or 300 can further include a solar cell layer "behind" the light emitting layer 104 (i.e., between the substrate 102 and the light emitting layer 104), the solar cell layer having one or more photovoltaic cells (also referred to as "solar cells") for converting light energy into electrical energy, and an electronic power converter layer behind the solar cell layer. The details of the solar cell layer and the electronic power converter layer are described in the applicant's co-pending U.S. Provisional Patent Application No. 62 / 831,828, entitled "Hybrid Energy Devices, Systems and Methods Thereof", the contents of which are incorporated herein by reference in their entirety.

[0143] For example, Fig.17 An example of a solar cell layer 540 including multiple sublayers is shown. As shown, the solar cell layer 500 in this example includes an anode sublayer 542 made of a suitable material such as indium tin oxide (ITO), a sublayer of zinc oxide (ZnO) 544, poly(ethyleneimine) and poly(ethyleneimine) ethoxylated (i.e., PEIE) 546, an organic solar cell sublayer 548 such as a polymer solar cell sublayer, a sublayer such as a bulk heterojunction (BHJ), an organic solar cell sublayer such as molybdenum trioxide (MoO3) 550, and a cathode sublayer 552 made of a suitable material such as silver (Ag) or aluminum (Al). The anode 542 and the cathode 552 are electrically connected to other layers such as electronic power converter layers.

[0144] Lighting system with controllable lighting patterns

[0145] Fig.18 A light emitting device 600 is shown that in some embodiments is used as an illumination or light source with a controlled illumination pattern by precisely controlling the light deflection angle using a metasurface or other light control structure. The illumination from the illumination system 600 is distributed according to a specific pattern onto an image plane 612, where one or more objects such as one or more plants are located.

[0146] For ease of notation, axes x and y represent orthogonal axes defining image plane 612, the z-axis is an axis along controllable illumination structure 100 and image plane 612 and is orthogonal to the x- and y-axes (i.e., orthogonal to image plane 612), the y deflection angle θ is the angle between the y-axis and the projection of light beam 610 on image plane 612, and the z deflection angle is the angle between the z-axis and the projection of the light beam 610 on the xz plane.

[0147] The light emitting device 600 is similar to Figure 4 The light emitting device 100 is shown and includes a light emitting layer 104 having one or more LEDs (not shown) and a light conversion layer 106 in front of the light emitting layer 104, such as a topological center vector control panel (TVCP) layer in these embodiments. Fig.18 Although not shown in the figure, the light emitting device 600 may further include a substrate 102 (similar to Figure 4 The light emitting device 100 shown).

[0148] The light emitting layer 104 includes an LED array as a light source, and emits a plurality of light beams 610 through the TVCP 106 toward an image plane 612 .

[0149] The TVCP 106 includes one or more optical transformation elements 122 (also referred to as “lenses” in these embodiments; Fig.18 ), arranged in a predefined pattern, wherein each optical transformation unit 122 comprises a metasurface. Each optical transformation unit 122 of the TVCP 106 controls the deflection angle θ and To control the direction of the light beam 610 to adjust the azimuth, elevation and angle of the light cone 610 in the image plane 612.

[0150] TVCP 106 effectively destroys the symmetry of the light distribution that would otherwise exist on image plane 612 (see FIG. 2 ). A slight change in the TVCP 106 will result in a significant change in the light intensity distribution on the image plane 612. Therefore, with a carefully configured TVCP 106, the illumination system 600 can use multiple light beams emitted from the light emitting layer 104 through the TVCP 106 to multiple predetermined incident points distributed on the image plane 612 to produce almost any light intensity distribution in the target illumination area on the image plane 612 as desired.

[0151] The lighting pattern (e.g., the size and shape of the target lighting area and the light intensity distribution therein) and the number of light sources (e.g., LEDs) determine the positions of the predetermined incident points, which can be calculated by using an appropriate optimization method to optimize an appropriate cost function under the constraint that all incident points must be within the target lighting area.

[0152] For example, to obtain a uniform (or more precisely, almost uniform) light intensity distribution, the normalized mean square error (NMSE) of the light intensity distribution is

[0153]

[0154] can be used as the cost function, where μ is the average light intensity on the image plane 612, I(x i ) is the light intensity of the i-th pixel, and N is the total number of pixels of the target illumination area on the image plane 612. An appropriate optimization method can be used to calculate the deflection angles θ and θ of each beam 610 that minimize the NMSE under the constraint that all incident points must be within the target illumination area. (which determines the location of its point of incidence).

[0155] Fig.19 The formation of the cost function is shown in one example where a uniform illumination pattern is to be generated within a circular target illumination area 622 on the image plane 612. Those skilled in the art will appreciate that cost functions for other illumination patterns may be similarly formed.

[0156] exist Fig.19 In the example shown, the illumination system 600 may use eight (8) light beams emitted at uniform angular intervals toward respective incident points 624 distributed on two concentric circles 626A and 626B (four points on each circle) within a circular area 622 of the image plane 612.

[0157] (1) Any suitable optimization method, such as an artificial intelligence (AI) algorithm, a machine learning algorithm, a gradient descent (GD) method, a simulated annealing (SA) method, and / or the like, may be used to find the global (or near-global) minimum of the NMSE of equation (1) and the corresponding deflection angles θ and θ of each light beam 610. .

[0158] (1) Fig. 20 is a flow chart showing the steps of a process 640 for finding the global (or near-global) minimum of the NMSE of equation (1) using the GD method using the following predefined parameters in the optimization:

[0159] The number of LEDs in the light-emitting layer 104;

[0160] The field of view (FOV) direction and angular span of each LED;

[0161] The shape of the target illumination area on the image plane 612;

[0162] The size of the target lighting area;

[0163] The distance between the light source and the target lighting area;

[0164] GD learning rate; and

[0165] Maximum number of iterations.

[0166] Those skilled in the art will appreciate that the above parameters may be customized by a user, or determined by the settings of the system 600 before the process 640 begins.

[0167] like Fig. 20 As shown, after the process 640 starts (step 642), the above parameters are loaded (step 644), and the initial state of each beam 610 is randomly selected (for example, for the state variables (θ, )'s initial value set) (step 646).

[0168] In step 648, the cost function in the current state is calculated relative to the state variables (θ, Then, the state variables (θ, θ) of all beams 610 are “moved” in the opposite direction to the gradient value of the current state multiplied by the learning rate. )(that is, changing the state variables (θ, )’s value) (step 650).

[0169] At step 652, process 640 checks whether the number of iterations has reached a maximum number of iterations (predefined by the system or user). If the number of iterations has reached the maximum number of iterations, the optimization has been completed and process 640 ends (step 654).

[0170] If, at step 652, the number of iterations has not reached the maximum number of iterations, the process 640 proceeds to step 656 to check whether the incident point of any beam 610 is outside the target illumination area. If not, the process 640 returns to step 648 to further "move" the state variables (θ, ).

[0171] If, at step 656, it is determined that the point of incidence of one or more light beams 610 is outside the target illumination area, the process 640 recalculates the state variables (θ, ) to locate its incident point at the boundary of the target illumination area along the opposite direction of the gradient value, and define one or more beams as fixed beams (i.e., their state variables (θ, ) will no longer be used for optimization) (step 658). Then, process 640 randomly selects an initial state for each remaining beam 610 (e.g., for state variables (θ, )'s initial value set) (step 660), and returns to step 648 for further optimization.

[0172] Process 640 may loop the above steps one or more times, and finally stop the experiment according to the maximum number of iterations, and achieve the global (or near-global) minimum of NMSE. Then, the state variables (θ, ) is used to configure the optical transformation unit 122 of the TVCP 106.

[0173] In some embodiments, the optimization process may divide the beams into multiple groups. Fig.19 In the example shown, the optimization process can divide the beams into two groups, each group including four beams whose incident points are in circle 626A or 626B. The optimization process can then form a cost function where the control variables that minimize the NMSE are the radius and rotation of circles 626A and 626B.

[0174] Figures 21 to 25 The optimization results of using the GD method to generate uniform light intensity distribution in target illumination areas of different shapes on the image plane are shown. The target illumination area includes a triangular illumination area ( Fig.21 ), square lighting area ( Fig. 22 ), pentagonal lighting area ( Fig.23 ), circular lighting area ( Fig.24 ) and donut-shaped or ring-shaped lighting areas ( Fig.25 ).

[0175] Metasurface Manufacturing Technology

[0176] The metasurface-based TVCP 106 can be fabricated using any suitable method, such as electron beam lithography. However, this technique is costly, slow, and only applicable to the fabrication of small metasurfaces. The TVCP 106 described above typically requires a metasurface with a diameter in the order of centimeters, so conventional electron beam lithography may not be fast and cost-effective.

[0177] In some embodiments, deep ultraviolet (UV) lithography is used to fabricate a metasurface such as the above-described metasurface-based TVCP 106. Although deep ultraviolet lithography is a mature technology in the semiconductor field, to the best of the applicant's knowledge, it has not yet been used to fabricate a metasurface.

[0178] Using this technique, a layer of chromium is deposited on a glass wafer. Then, a resist is spin-coated on the wafer, followed by UV exposure and development. Finally, the metasurface pattern is defined by etching the chromium layer. This technique allows multiple metasurfaces to be fabricated on a large wafer through a single process, resulting in fast and cost-effective manufacturing. In addition, deep ultraviolet lithography can also be used to fabricate metasurfaces in the visible and infrared wavelength range using silicon dioxide, titanium dioxide, or amorphous silicon.

[0179] Lighting system with uniform lighting pattern

[0180] As mentioned above, conventional lighting systems such as LED panels used for indoor plant growing typically do not produce an even distribution of light across the plants.

[0181] In some embodiments, similar to Figure 4 and 18 In the embodiment shown, by covering the angle-controlled light conversion layer 106 such as a TVCP layer in front of the light-emitting layer 104, uniform or nearly uniform illumination of the lighting system 700 such as a grow light system can be obtained. Fig.26 As shown, the light emitting layer 104 emits a plurality of light beams 702 through the TVCP 106 toward an image plane (not shown). The spatial distribution of each light beam 702 can be determined by angles β, θ and , where angle β determines the angular span of beam 702, and angles θ and The direction of light beam 702 is determined.

[0182] The TVCP 106 includes one or more light transforming units 122 arranged in a predefined pattern, wherein each light transforming unit 122 includes a metasurface. Each light transforming unit 122 of the TVCP 106 is configured to precisely control the angles β, θ, and , to arbitrarily change the angular extent, altitude, and latitude of the light cone in the image plane. TVCP 106 effectively destroys the symmetry of the light distribution that would otherwise exist in the image plane (see, for example, FIG. 2 ). The use of TVCP 106 is powerful because the angles β, θ, and / or Small changes in can produce significant differences in the intensity distribution in the image plane. Thus, almost arbitrary intensity distributions can be generated.

[0183] The illumination system 700 can be used to generate a uniform illumination pattern at an image plane and can be used as a grow light. It is worth noting that for ease of fabrication and implementation, the number of metasurfaces with different designs needs to be minimized.

[0184] In some embodiments, the TVCP 106 of the uniform illumination lighting system 700 may include only two types of metasurfaces, including a set of splitting metasurfaces and a set of converging metasurfaces.

[0185] The splitting metasurface is a polarization-sensitive metasurface that changes the angles β, θ, and In these embodiments, the light emitting layer 104 (eg, an LED light emitting layer) emits unpolarized light which ensures equal power is split into two opposite directions at the splitting metasurface.

[0186] like Fig.27A As shown, the splitting metasurfaces 122A and 122B of the TVCP 106 are configured to distribute light beams 702A and 702B, respectively, at the boundaries of a desired illumination pattern on an image plane (not shown).

[0187] Fig.27B An illumination pattern 704A on an image plane is shown, in which light energy is significantly distributed along vertical boundaries (the guided light is hereinafter referred to as “vertical boundary focused light”), the illumination pattern 704A being created by using a segmented metasurface to split the light from the light-emitting layer to guide the light vertically to the corresponding boundaries.

[0188] same, Fig.27C 704B on the image plane, where the light energy is significantly distributed along the horizontal boundary (the guided light is hereinafter referred to as “horizontally boundary focused light”), is shown. The illumination pattern 704B uses a 90° rotated split metasurface (similar to Fig.27B A splitting metasurface (the one used in , but with the light energy distribution rotated 90°) was created to split the light from the light-emitting layer to guide the light horizontally to the corresponding boundaries.

[0189] like Fig.27B The horizontal / vertical bezel focused lights shown can be directed to the same target area on the image plane to allow the light directed therefrom to overlap and form an illumination pattern 706 where the light energy is concentrated substantially along the four boundaries of the area; see Fig.28 Conceptual representation in .

[0190] like Fig.29A and 29B As shown, the converging metasurface 122C is configured to modify the angle β of the light beam 702C without changing the direction of the cone of light beam 702C. Therefore, the converging metasurface 122C distributes the light beam 702C in the center of the target area on the image plane, thereby producing an illumination pattern in which the light energy is substantially focused at its center.

[0191] like Fig.30 As shown in the conceptual representation shown, the illumination pattern 706 (which is a combination of the two) can be combined by using the splitting metasurfaces 122A and 122B and the converging metasurface 122C to direct the light beams to the same target area. Fig.28 The combination of illumination patterns 704A and 704B shown) and 708 are used to obtain uniform light distribution in the target area.

[0192] This uniform light distribution is substantially independent of the distance between the metasurface-based TVCP 106 and the image plane 712. Fig.31 As shown, the light distribution is only scaled at different distances without compromising the uniformity of the distribution.

[0193] Fig.32 An example implementation of a TVCP 106 is shown using an array of metasurfaces 122. For ease of illustration, only two metasurfaces 122 are shown.

[0194] In these embodiments, the TVCP 106 includes a metasurface housing 722 covering the LEDs 110 mounted on a printed circuit board (PCB) 724 of the light emitting layer 104. The metasurface housing 722 includes a plurality of containers 726 at positions corresponding to the LEDs 110. Each container 726 includes an inner surface that expands outwardly, the inner surface having an inner opening for receiving light emitted from the light emitting layer and an outer opening for passing the received light, the area of ​​the outer opening being larger than the area of ​​the inner opening.

[0195] In these embodiments, the inner surface of the container 726 is reflective to reflect light (emitted from the LED 110 therein) at high angles to aid in overall illumination, thereby increasing the efficiency of overall illumination. Maximum luminous flux is achieved when the cross-section of the inner surface is parabolic and the LED is located at its focus. Fig.33 is a photograph showing the metasurface shell 722 coupled to the light emitting layer 104.

[0196] The plurality of metasurface units 122 are secured or otherwise coupled to the container 726 of the metasurface housing 722 using a suitable fastening device, such as epoxy, glue, and / or the like, thereby ensuring alignment of the LEDs 110 and the metasurface units 122 .

[0197] Polarization selective illumination

[0198] Plants are often made up of organized components. As a result, the absorption of light by plants tends to be polarization-sensitive. In other words, plants may absorb more light in one specific polarization state than in another. Therefore, using light in a specific polarization state can optimize photosynthesis.

[0199] In some embodiments, the metasurface-based light conversion layer 106 of the grow lamp disclosed herein may be polarization selective, which may be achieved by arranging the nanoscale structures 124 of the metasurface to have an asymmetric basic geometry 732, such as Fig.34 As shown. Therefore, a grow light with such a metasurface-based light conversion layer 106 can be used to illuminate plants with light in a specific polarization state to optimize the light for photosynthesis. In general, the metasurface of the light conversion layer 106 can be designed to illuminate plants in various polarization states, including linear polarization states, circular polarization states, and generally elliptical polarization states. Linearly polarized illumination can be used to optimize photosynthesis of plants composed of fibers oriented in a specific direction, and circularly polarized illumination can be used to optimize photosynthesis of plants composed of components with helicity.

[0200] TVCP of photovoltaic cells based on metasurfaces

[0201] In solar cells, although always desirable, perfect light absorption by the photovoltaic cell is difficult to achieve due to the mismatch between the spectrum of the incident light and the spectral response of the photovoltaic cell. As shown in FIG. 35, light reflection 842 occurring on the surface of the photovoltaic cell 844 also results in the loss of solar energy that might otherwise be absorbed by the photovoltaic cell 844.

[0202] In some embodiments, the metasurface-based TVCP can be incorporated into a photovoltaic panel having, for example, one or more silicon-based and / or one or more quantum dot photovoltaic cells, wherein the metasurface-based TVCP can be configured to efficiently transmit light of a specific wavelength to the photovoltaic cell. In addition, the metasurface-based TVCP allows the size of the photovoltaic panel to be significantly reduced.

[0203] As will be appreciated by those skilled in the art, a metasurface includes nanoscale structures. The geometry and distribution of the nanoscale structures can be designed or otherwise configured to meet the requirements of a particular application. For example, a metasurface can be designed to pass or otherwise transmit a portion of incident light of a target spectrum and completely reflect another portion of the incident light out of the target spectrum.

[0204] In such Fig.36 In some of the illustrated embodiments, the metasurface-based TVCP 106 can be arranged in front of a photovoltaic panel 852 having, for example, one or more silicon-based and / or quantum dot photovoltaic cells. The metasurface-based TVCP 106 includes a plurality of metasurface units (not shown) having a spectral response that matches the spectral response of the photovoltaic cell. Therefore, the combination of the metasurface-based TVCP 106 and the photovoltaic panel 852 is significantly more effective than using the photovoltaic panel 852 alone, because when the photovoltaic panel 852 is used alone, the spectrum that is not fully absorbed may become heat and other undesirable effects, thereby reducing its performance. This arrangement or combination is particularly important for indoor photovoltaic cells that obtain light energy from artificial light sources such as LEDs, where the metasurface units can be designed to match the specific illumination spectrum of the light source and reject other light that cannot be effectively absorbed by the photovoltaic cell.

[0205] Another important application of metasurfaces is their ability to redirect light into different directions as described above. Fig.37 As shown, the front metasurface-based TVCP 106 can be a photovoltaic panel 852, wherein the metasurface-based TVCP 106 is configured to focus incident light 854 into a small area of ​​the photovoltaic panel 852, and thus, the size of the photovoltaic panel 852 can be significantly reduced. FIG38 shows a prior art photovoltaic panel 844 without a metasurface-based TVCP 106 for comparison.

[0206] Super-directional screens using metasurfaces

[0207] Conventional screens or displays typically have a wide field of view (FOV) angular span. However, in some applications, it may be desirable to limit the FOV of the display.

[0208] Herein, the term FOV refers to the angular extent of illumination (e.g., cone or other shape) emitted from a component (e.g., LED layer, metasurface layer, etc.), where in various embodiments, the light can be used for illumination or for displaying one or more images. The FOV can be characterized by the direction and three-dimensional (3D) angular span of light emitted from the component.

[0209] For example, displays in vehicles or aircraft are typically viewed by only one person. However, as shown in FIG39 , a display 862 with a wide FOV 868 (i.e., a FOV 868 with a wide angular span) in a vehicle or aircraft (not shown) will unnecessarily emit light to the surrounding area, which may result in reduced brightness for the user 864 in front of it, waste of light energy, and interference with people 866 adjacent to it.

[0210] Likewise, wide FOV displays used in homes or theaters illuminate surrounding areas such as walls and ceilings, resulting in reduced brightness for users in front and wasted light energy.

[0211] In addition, in some applications that require enhanced security or privacy, such as displays in ATMs, displays in banks, and laptop displays that users use for sensitive work, highly directional displays may be required because wide FOV displays in these applications may cause security or privacy risks in addition to the above-mentioned problems of reduced brightness, wasted light energy and / or interference with people nearby.

[0212] According to some embodiments of the present disclosure, Fig.40 A super-directional screen or display 870 using a metasurface is shown. The super-directional screen 870 includes a display or display layer 872 and a metasurface panel or layer 874 in front of it.

[0213] Similar to the light transformation layer 106 described previously, the metasurface panel 874 includes a plurality of metasurface units constructed in an array of nanoscale structures that direct light in a desired direction so as to confine light emitted from the display 872 to a predefined FOV 878 that is smaller than the FOV 876 of the display 872, thereby creating a virtual visual barrier such that only the intended person 864 can see what is shown on the display 872.

[0214] The Super Directional Screen 870 has several advantages, including:

[0215] Because the light energy is concentrated in a smaller area, the brightness is higher;

[0216] Improved by avoiding illumination of unintended areas and evenly distributing light energy to intended areas

[0217] Power efficiency; and

[0218] Enhanced security and privacy, as visual information can only be viewed by the intended person in front of it.

[0219] As mentioned above, metasurfaces can be designed to interact differently with light of different polarization states, which is achieved by fabricating nanostructures of the metasurface with asymmetric geometries.

[0220] Fig.41 A variable field of view (VFOV) screen or display 880 in some embodiments is shown. The VFOV display 880 includes a display 872, a polarization control panel 884 in front of the display 872, and a polarization-sensitive metasurface panel 886 in front of the polarization control panel 884.

[0221] In these embodiments, the polarization control panel 884 may be implemented using a liquid crystal polarization rotator and controlled by an adjustable control signal V to control the polarization of light emitted from the display 872 to either of two orthogonal polarization states.

[0222] The MFOV display 880 is similar to Fig.11A and 11B The light emitting device or display 200 shown, the MFOV display 880 in these embodiments is not like Fig.11A and 11B In contrast, the polarization-sensitive metasurface panel 886 in these embodiments interacts with polarized light to direct light in a first polarization state to a first FOV having a first angular span 888 and to direct light in a second polarization state to form a second FOV having a second angular span 890. For example, the first angular span 888 may be a wide angular span suitable for multiple users 864 and 866 surrounding the MFOV display 880 to view the displayed content, and the second angular span 890 may be a narrow angular span smaller than the first angular span 888 to allow only the user 864 to view the displayed content.

[0223] In the above embodiment, when the control signal is at a first voltage, the polarization control panel 884 polarizes all light passing through it to a first polarization state, and when the control signal is at a second voltage, polarizes all light passing through it to a second polarization state. In this way, the user 864 can switch the FOV of the MFOV display 880 between the first and second angular spans for sharing the displayed content with a person adjacent thereto and for creating a virtual visual barrier to prevent others from viewing the displayed content, respectively.

[0224] exist Fig.42 In another embodiment shown, the MFOV display 880 is similar to Fig. 10A and 10B The display shown. Specifically, the display 872 includes two groups of cells (pixels or sub-pixels, depending on the design), where each group of cells can be used to display an image.

[0225] Accordingly, each of the polarization control panel 884 and the polarization-sensitive metasurface panel 886 also includes two groups of units corresponding to the two groups of units of the display 872. Each group of units of the polarization control panel 884 is controlled by a separate control signal V1 or V2, and each group of units of the polarization-sensitive metasurface panel 886 matches a specific polarization state and directs light having the polarization state to a specific FOV.

[0226] Thus, the display 872 can use these two groups of pixels / cells to display two images simultaneously, and the polarization control panel 884 polarizes the light of the first and second images to the first and second polarization states. The polarization-sensitive metasurface panel 886 then directs the light in the first polarization state (i.e., the first image) to a first FOV having a wide angular span for sharing the first image with multiple persons 864 and 866, and directs the light in the second polarization state (i.e., the second image) to a second FOV having a narrow angular span for preventing the person 866 from viewing the second image.

[0227] For example, Fig.43A and 43B As shown, the display will simultaneously display two images 892A and 892B, wherein image 892A will be displayed in a first FOV having a wide angular span, and image 892B will be displayed in a second FOV having a narrow angular span.

[0228] like Fig.43C As shown, the display 872 divides pixels into a first group of pixels 894A and a second group of pixels 894B arranged side by side for simultaneously displaying images 892A and 892B side by side.

[0229] like Fig.43DAs shown, the polarization control panel 884 includes a plurality of polarization units 894 corresponding to pixels of the display 872, wherein a first group of polarization units 896A corresponds to a first group of pixels 894A for polarizing light passing therethrough to a first polarization state, and a second group of polarization units 896B corresponds to a second group of pixels 894B for polarizing light passing therethrough to a second polarization state.

[0230] like Fig.43E As shown, the polarization-sensitive metasurface panel 886 includes a plurality of metasurface units 898 corresponding to the polarization units 894 of the polarization control panel 884, and guides light passing through in a first polarization state to a first FOV (having a wide angular span), and guides light passing through in a second polarization state to a second FOV (having a narrow angular span).

[0231] As a result, the first image 892A is directed to the first FOV, and the second image 892B is directed to the second FOV. Fig.43F As shown, images 892A and 892B are visible to user 864 who is located in both the first and second FOVs, and user 866 who is located only in the first FOV (having a wide angular span) can only see first image 892A. In other words, image 892B is not visible to user 866 who is located only in the first FOV.

[0232] Three-dimensional (3D) displays using metasurfaces

[0233] Fig.44 A 3D display 900 using a metasurface according to some embodiments of the present disclosure is shown. As shown, the 3D display 900 includes a display 872 and a polarization-sensitive metasurface panel 886 in front of it. The display 872 displays an image by emitting unpolarized light (which generally includes two polarization states). The polarization-sensitive metasurface panel 886 is configured to direct light in a first polarization state to a first FOV 888, and to direct light in a second polarization state to a second FOV 890 slightly laterally offset from the first FOV 888. Then, a user 864 wearing glasses with lenses polarized to different polarization states sees the first image in one eye and the second image in the other eye, wherein the second image has a slight perspective distortion compared to the first image, thereby creating a 3D perception of the displayed image.

[0234] In some embodiments, 3D display 900 may further include a polarization control panel 884 sandwiched between display 872 and polarization-sensitive metasurface panel 886. Polarization control panel 884 alternately polarizes light from display 872 to a first polarization state and a second polarization state in operation.

[0235] Fig.45A 3D display 920 using a metasurface according to some embodiments of the present disclosure is shown. The 3D display 920 is similar to Fig.44 However, polarization-sensitive metasurface panel 886 is configured to direct light in a first polarization state to a first FOV 888 that covers only the first eye of user 864, and to direct light in a second polarization state to a second FOV 890 that covers only the second eye of user 864. Thus, user 864, without wearing glasses with polarized lenses, can see a first image in one eye and a second image in the other eye, wherein the second image has a slight perspective distortion compared to the first image, thereby creating a 3D perception of the displayed image.

[0236] In some embodiments, 3D display 920 may further include a polarization control panel 884 sandwiched between display 872 and polarization-sensitive metasurface panel 886. Polarization control panel 884 alternately polarizes light from display 872 to a first polarization state and a second polarization state in operation.

[0237] Solar cell angle correction

[0238] In the prior art, solar panels may encounter the problem of sunlight reflection.

[0239] As those skilled in the art will appreciate, the angle of incidence of sunlight may have a significant effect on the efficiency of photovoltaic cells. As shown in FIG. 46 , when sunlight 944 is vertically irradiated on the photovoltaic cells of solar panel 942, the photovoltaic cells of solar panel 942 have the highest efficiency.

[0240] As shown in FIG47, at different times when sunlight 944 is at a non-perpendicular angle to the photovoltaic cells of solar panel 942, a portion 946 of the sunlight is reflected and the efficiency of the photovoltaic cells is reduced. Therefore, the photovoltaic cells of a fixed solar panel will have different efficiencies at different times of the day and different days of the year. Although solar tracking systems have been used to increase the efficiency of photovoltaic panels by rotating the solar panel to follow the sun, such systems require tracking systems and moving parts, making them expensive to manufacture and use.

[0241] Fig.48 and 49A solar energy collection device 970 is shown, which includes a solar panel 972 having one or more photovoltaic cells and a plurality of TVCPs 974 in front thereof. By using a polarization-sensitive metasurface, where the response of each TVCP 974 can be varied using an embedded polarization control panel, the plurality of TVCPs 974 can change the direction of sunlight 944 so that incident sunlight 944 within a predetermined range of incident angles becomes perpendicular to the photovoltaic cells when striking the solar panel 972, thereby improving efficiency without the need for a sun tracking system or moving parts.

[0242] In some embodiments described above, the light emitting device and / or system is used for plant growth, such as for indoor or outdoor plant growth. However, those skilled in the art will appreciate that the light emitting device and / or system disclosed herein may alternatively be used in other applications such as street lamps.

[0243] Although embodiments have been described above with reference to the accompanying drawings, those skilled in the art will appreciate that changes and modifications may be made without departing from the scope defined by the appended claims.

Claims

1. A light emitting device, comprising: a light-emitting layer for emitting light; as well as a light conversion layer coupled to the light emitting layer, the light conversion layer comprising one or more light conversion units, each light conversion unit comprising a metasurface for adjusting one or more parameters of light emitted from the light emitting layer; wherein the light-emitting layer comprises one or more light-emitting units; wherein the light conversion layer comprises a housing comprising one or more containers for receiving the one or more metasurfaces; and The one or more containers are located at positions corresponding to the positions of the one or more light-emitting units, so as to align the one or more metasurfaces with the one or more light-emitting units. 2 . The light emitting device according to claim 1 , wherein the light emitting layer comprises one or more light emitting diodes (LEDs) for emitting light. 3 . The light emitting device according to claim 1 , wherein the light conversion layer is printed onto the light emitting layer.

4. The light-emitting device according to claim 1, wherein each of the one or more containers includes an inner surface that expands outward, the inner surface having an inner opening for receiving light emitted from the light-emitting layer and an outer opening for allowing the received light to pass, and an area of ​​the outer opening is larger than an area of ​​the inner opening.

5. The light emitting device of claim 4, wherein an inner surface of each of the one or more containers is reflective. 6 . The light emitting device according to claim 4 , wherein a cross section of an inner surface of each of the one or more containers has a parabolic shape.

7. A light emitting device, comprising: a light-emitting layer for emitting light; as well as a light conversion layer, comprising one or more light conversion units, each light conversion unit comprising a metasurface, at least one metasurface being polarization selective, for selectively allowing light having a predefined polarization state emitted from the light emitting layer to pass through the at least one metasurface; wherein the light-emitting layer comprises one or more light-emitting units; wherein the light conversion layer comprises a housing comprising one or more containers for receiving the one or more metasurfaces; and The one or more containers are located at positions corresponding to the positions of the one or more light-emitting units, so as to align the one or more metasurfaces with the one or more light-emitting units.

8. The light emitting device of claim 7, wherein each of the one or more metasurfaces comprises a plurality of nanoscale structures arranged in an asymmetric basic geometric shape.

9. The light emitting device according to claim 7 or 8, further comprising: The polarization control layer is sandwiched between the light emitting layer and the light conversion layer and is used to polarize the light emitted from the light emitting layer.

10. The light emitting device of claim 7, wherein the light emitting device is a grow light for promoting the growth of one or more plants.

11. A light emitting device for promoting the growth of one or more plants, the device comprising: a light-emitting layer for emitting light; as well as at least one light transforming layer comprising one or more light transforming units, each light transforming unit comprising a metasurface for adjusting one or more parameters of light emitted from the light emitting layer so as to optimize a lighting configuration for the one or more plants; wherein the light-emitting layer comprises one or more light-emitting units; wherein the light conversion layer comprises a housing comprising one or more containers for receiving the one or more metasurfaces; and The one or more containers are located at positions corresponding to the positions of the one or more light-emitting units, so as to align the one or more metasurfaces with the one or more light-emitting units.

12. A display device, comprising: a light-emitting layer for emitting light; as well as at least one light transforming layer comprising one or more light transforming units, each light transforming unit comprising a metasurface for adjusting one or more parameters of light emitted from the light emitting layer so as to display one or more images; wherein the light-emitting layer comprises one or more light-emitting units; wherein the light conversion layer comprises a housing comprising one or more containers for receiving the one or more metasurfaces; and The one or more containers are located at positions corresponding to the positions of the one or more light-emitting units, so as to align the one or more metasurfaces with the one or more light-emitting units.

13. A light emitting device, comprising: a light-emitting layer for emitting light; a polarization control layer coupled to the light emitting layer for polarizing the light emitted from the light emitting layer; as well as at least one light conversion layer coupled to the polarization control layer, the at least one light conversion layer comprising one or more light conversion units, each light conversion unit comprising at least one metasurface, at least one metasurface being polarization selective for selectively allowing polarized light from the polarization control layer to pass through the at least one metasurface to switch between different illumination patterns or images; wherein the light-emitting layer comprises one or more light-emitting units; wherein the light conversion layer comprises a housing comprising one or more containers for receiving the one or more metasurfaces; and The one or more containers are located at positions corresponding to the positions of the one or more light-emitting units, so as to align the one or more metasurfaces with the one or more light-emitting units.

14. A light emitting device, comprising: a light-emitting layer for emitting light; a polarization control layer coupled to the light emitting layer for polarizing the light emitted from the light emitting layer; as well as at least one light conversion layer coupled to the polarization control layer, the at least one light conversion layer comprising one or more light conversion units, each light conversion unit comprising at least one metasurface, at least one metasurface being polarization selective for selectively allowing polarized light from the polarization control layer to pass through the at least one metasurface so as to generate a plurality of different illumination patterns or images at different locations; wherein the light-emitting layer comprises one or more light-emitting units; wherein the light conversion layer comprises a housing comprising one or more containers for receiving the one or more metasurfaces; and The one or more containers are located at positions corresponding to the positions of the one or more light-emitting units, so as to align the one or more metasurfaces with the one or more light-emitting units.

15. A light emitting device, comprising: a light-emitting layer for emitting light; as well as a light conversion layer in front of the light emitting layer, the light conversion layer comprising a plurality of light conversion units, each light conversion unit comprising a metasurface for directing light emitted from the light emitting layer to a target area to form a predefined light distribution pattern; wherein the light-emitting layer comprises one or more light-emitting units; wherein the light conversion layer comprises a housing comprising one or more containers for receiving the one or more metasurfaces; and The one or more containers are located at positions corresponding to the positions of the one or more light-emitting units, so as to align the one or more metasurfaces with the one or more light-emitting units.

16. The lighting device of claim 15, wherein the predefined light distribution pattern is a substantially uniform light energy distribution over the target area.

17. A light-emitting device according to claim 16, wherein the plurality of metasurfaces include a first group of metasurfaces for directing light emitted from the light-emitting layer to a boundary of the target area; and a second group of metasurfaces for directing light emitted from the light-emitting layer to a center of the target area so as to produce a substantially uniform light energy distribution on the target area.

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