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

Abstract

To provide a light-emitting device to promote plant growth.SOLUTION: A device includes a light-emitting layer including one or more light-emitting diodes for emitting light, and at least one light-converting layer having one or more light-converting units, each of the light-converting units has a metasurface for adjusting one or more parameters of the light emitted from the light-emitting layer.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 62 / 862,853, filed Jun. 18, 2019, and U.S. Provisional Patent Application No. 62 / 961,317, filed Jan. 15, 2020, the entire contents of each of which are incorporated herein by reference.

[0002] Field of Disclosure The present disclosure relates to light - emitting methods, devices, and systems, particularly light - emitting methods, devices, and systems that use metasurfaces for controlling the emitted light.

Background Art

[0003] Background Light - emitting diodes (LEDs) are known in many industries and are widely used mainly as low - output light displays. In recent years, LEDs with increased output or luminance have been developed and are used as light sources for lighting. For example, LED lights with improved energy efficiency, safety, and reliability are replacing other types of lights on the market, such as incandescent lamps and compact fluorescent lamps (CFLs). Since daily lighting significantly contributes to the burden on the power grid and greatly increases the overall power generation requirement, the energy efficiency of LEDs will play an important role in future energy conservation. Due to their excellent energy efficiency, LEDs will dominate the lighting market.

[0004] High - efficiency LEDs are replacing conventional lighting solutions in various applications such as flashlights, portable lights, lamps, and streetlights. LEDs can be powered by various types of power sources, such as batteries, conventional power grids, renewable energy systems, and energy storage systems, e.g., systems using photovoltaic (PV) panels and battery banks, thereby providing great flexibility in adapting lighting solutions to specific usage scenarios.

[0005] In many lighting solutions, it may be preferable to configure a light source, such as an LED light source, to form a converging beam and a focus in a predetermined area to emit directional light, for example to obtain improved lighting intensity, to form a parallel beam to reach a distant target, and / or to form a diverging beam to illuminate a wide area. In some lighting solutions, the direction of the light from the light source may preferably be adjustable. In the prior art, mirrors or reflective surfaces are typically used to form directional light, and mechanical means are often used to change the orientation of the mirror or reflective surface to adjust the direction of the light. Such directional lighting means are typically relatively large in size, slow in response, and low in efficiency.

[0006] LEDs with increased output and / or luminous intensity are also used as light sources for growing plants such as plants. Such LEDs, sometimes called LED grow lights, offer various advantages such as providing light of an exact wavelength, high intensity, high efficiency, etc. LED grow lights are also advantageous for growing indoor plants because the process of growing plants can be carried out in a controlled environment with far fewer risks and other unwanted outdoor variables.

[0007] Plant growth occurs as a result of the "photosynthesis" process. As is known in the art, the photosynthesis process uses energy from light to convert carbon dioxide (CO2) into organic substances. Specifically, light energy is absorbed through special proteins containing chlorophyll pigments that are present in photosynthetic cell membranes called chloroplasts. Photosynthetic cells are mainly present in the leaves of plants.

[0008] However, chlorophyll absorbs only the energy from specific parts or colors of the light spectrum. The effective spectrum spans the blue and red spectra. Since the green part of the light spectrum is reflected, the leaves of plants are usually green. When the photosynthetic cells in the leaves die and the chlorophyll decomposes, other pigment molecules in the leaves have a significant impact on light reflection while the chlorophyll decomposes to the extent that the leaves show only brown color.

[0009] Thus, it is known that different pigments of chlorophyll absorb light of specific wavelengths and contribute to photosynthesis, and the photosynthetic efficiency or rate has a strong correlation with the spectrum of illumination.

[0010] For example, rice grown under blue and red illumination has a higher photosynthetic efficiency than that grown under red illumination only. Pea leaves grown under red LED light contain a higher level of β-carotene than those grown under blue or white LED light.

[0011] Light intensity is another influencing factor in photosynthesis due to the response of photosynthetic organisms to high light intensity to reduce the impact of stress. Under red LED light, wheat seedlings accumulate chlorophyll at 100 μmolm -2 s -1 but do not accumulate at 500 μmolm -2 s -1 .

[0012] Plants are usually observed to absorb the blue light spectrum during early growth, and then absorb the red light spectrum more as the plants mature and during the flowering period. Some plants are also observed to have highly ordered components that are sensitive to the interaction with light polarization. For example, such plants may absorb or reflect light of a specific polarization state more efficiently than light of other polarization states.

[0013] In addition, plants can sense the illumination duration and duration time and change the growth rate of the plants accordingly.

[0014] Plant cultivation using a certain or broadly defined lighting configuration is not energy-efficient and not optimal for photosynthesis. Conventional LED grow lights in the prior art usually cannot provide an optimized lighting configuration for optimizing the physiological processes of growing plants because they do not consider the aforementioned factors. Moreover, different plants require different light characteristics (e.g., intensity, spectrum, polarization, time, etc.) to achieve the best growth ability. However, conventional LED grow lights in the prior art cannot adapt to the requirements of plants and cannot exhibit appropriate light characteristics.

[0015] For example, conventional lighting systems such as LED panels used for growing indoor plants usually do not provide uniform light distribution across the entire plant. Their light distribution often has the strongest intensity at the center and gradually decreases as it moves away from the center.

[0016] Figure 1A shows a conventional light source 10 that emits a light beam 12 towards a square image plane 14 away from the light source 10. Figure 1B shows the light intensity distribution 16 on the image plane 14. As can be seen, the conventional light source 10 does not provide uniform light distribution on the image plane 14. Rather, the light intensity distribution 16 on the image plane 14 is strongest at the center of the image plane 14 and gradually decreases as it moves away from the center. Moreover, the intensity distribution 16 is symmetric with respect to the incident point of the light beam 12 on the image plane 14.

[0017] Figures 2A and 2B show the lighting pattern generated by an LED panel 10 within a 6×6 square meter (m 2 ) image plane 14 approximately 3 meters (m) away from the panel 10 obtained using the ray tracing method. The intensity distribution is clearly non-uniform.

[0018] Therefore, with such a light source 10 that provides sufficient light around the plant, over-illumination will occur at the center of the plant, which will cause growth failure of the plant. On the other hand, by providing sufficient illumination at the center of the plant, inefficient illumination will occur around the plant, and growth failure of the plant will also occur. Such an intensity distribution is due to the symmetry of the image plane center with respect to the light emitter.

[0019] Such a light source 10 may not be desirable for other applications. For example, a street lamp using such a light source 10 may cause glare and overall inefficient illumination.

[0020] LEDs are also used in indoor and outdoor displays that require careful control of various light characteristics such as intensity, polarization, and / or time with a rapid response.

Summary of the Invention

Problems to be Solved by the Invention

[0021] Summary Therefore, there is always a need for LED devices, systems, and methods with controlled light characteristics.

Means for Solving the Problems

[0022] 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 a light conversion layer coupled to the light emitting layer, the light conversion layer including one or more light conversion units, each light conversion unit including a metasurface for adjusting one or more parameters of the light emitted from the light emitting layer.

[0023] In some embodiments, the light emitting layer includes one or more light emitting diodes (LEDs) for emitting light.

[0024] In some embodiments, the light conversion layer is printed on the light emitting layer.

[0025] In some embodiments, the light-emitting layer includes one or more light-emitting units, the light conversion layer includes a housing having one or more receiving portions for receiving one or more metasurfaces, and the one or more receiving portions are located at positions corresponding to the positions of the one or more light-emitting units to align the one or more metasurfaces with the one or more light-emitting units.

[0026] In some embodiments, each of the one or more receiving portions includes an outwardly expanding inner surface having an inner opening for receiving light emitted from the light-emitting layer and an outer opening for passing the received light, and the outer opening has an area larger than the area of the inner opening.

[0027] In some embodiments, the inner surface of each of the one or more receiving portions is reflective.

[0028] In some embodiments, the cross-section of the inner surface of each of the one or more receiving portions has a paraboloid shape.

[0029] 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 a light conversion layer including one or more light conversion units, each light conversion unit including a metasurface, and at least one metasurface being polarization selective to selectively pass light emitted from the light-emitting layer having a predetermined polarization state through the metasurface.

[0030] In some embodiments, each of the one or more metasurfaces includes a plurality of nanostructures arranged in an asymmetric base shape.

[0031] 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.

[0032] In some embodiments, the light-emitting device is a grow light for promoting the growth of one or more plants.

[0033] According to one aspect of the present disclosure, a light-emitting device for promoting the growth of one or more plants is provided. The light-emitting device includes a light-emitting layer for emitting light and at least one light conversion layer including one or more light conversion units, wherein each light conversion unit includes a metasurface for adjusting one or more parameters of the light emitted from the light-emitting layer in order to optimize the lighting configuration for one or more plants.

[0034] 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, wherein each light conversion unit includes a metasurface for adjusting one or more parameters of the light emitted from the light-emitting layer in order to display one or more images.

[0035] 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, the at least one light conversion layer including one or more light conversion units, each light conversion unit including at least one metasurface, and the at least one metasurface being polarization selective to selectively pass the polarized light from the polarization control layer through the metasurface for switching between different illumination patterns or 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, the at least one light conversion layer including one or more light conversion units, each light conversion unit including at least one metasurface, and the at least one metasurface being polarization selective to selectively pass the polarized light from the polarization control layer through the metasurface for creating a plurality of different illumination patterns or images at different positions.

[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 toward a radiation source field of view (FOV), and at least one metasurface layer on the front side of the light emitting layer for guiding the light emitted from the light emitting layer toward a first FOV having an angular spread smaller than the angular spread of the radiation source FOV.

[0038] In some embodiments, the light emitting device further includes 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 the light emitted from the light emitting layer into a first polarization state or a second polarization state in response to a control signal. The at least one light conversion layer is configured to guide the light from the polarization control layer in the first polarization state toward a first FOV having an angular spread smaller than the angular spread of the radiation source FOV, and to guide the light from the polarization control layer in the second polarization state toward a second FOV having an angular spread larger than the angular spread of the first FOV.

[0039] 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 a light conversion layer on the front side of the light emitting layer, the light conversion layer including a plurality of light conversion units, each light conversion unit including a metasurface for guiding the light emitted from the light emitting layer toward a target region to form a predetermined light distribution pattern.

[0040] In some embodiments, the predetermined light distribution pattern is a substantially uniform light energy distribution on the target region.

[0041] In some embodiments, the plurality of metasurfaces includes a first set of metasurfaces for guiding the light emitted from the light emitting layer toward the boundary of the target region, and a second set of metasurfaces for guiding the light emitted from the light emitting layer toward the center of the target region to generate a substantially uniform light energy distribution on the target region.

[0042] According to one aspect of the present disclosure, a solar energy collection device is provided. The solar energy collection device includes a photovoltaic layer having a plurality of photovoltaic cells, and at least one metasurface layer on the front side of the photovoltaic layer for substantially guiding light to the photovoltaic layer without causing reflection in the photovoltaic layer.

[0043] In some embodiments, the solar energy collection device includes a plurality of metasurface layers for guiding light at an incident angle within a predetermined range so as to impinge perpendicularly on the photovoltaic layer.

[0044] 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 on the front side of the light emitting layer for guiding the light emitted from the light emitting layer in a first polarization state toward a first FOV, and for guiding the light emitted from the light emitting layer in a second polarization state toward a second FOV, wherein the first FOV and the second FOV are superimposed to form a three-dimensional (3D) perception for a user wearing glasses having lenses of different polarization states, and are laterally shifted from each other.

[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 on the front side of the light emitting layer for guiding the light emitted from the light emitting layer in a first polarization state toward a first FOV, and for guiding the light emitted from the light emitting layer in a second polarization state toward a second FOV, wherein the first FOV and the second FOV are laterally shifted from each other such that the first FOV is visible only to the first eye of the user at a predetermined distance, and the second FOV is visible only to the second eye of the user at a predetermined distance, in order to form a 3D perception for the user.

Brief Description of the Drawings

[0046] Brief Description of the Drawings

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[0047] DETAILED DESCRIPTION Light Emitting Device Having a Light Emitting Layer and a Light Conversion Layer Now, referring to FIGS. 3 and 4, a light emitting device (also referred to as an "illumination device" or an "optical device") is shown and is generally designated by reference numeral 100 according to some embodiments of the present disclosure. Herein, the light emitting device can be a device for illumination, a device for promoting the growth of plants, or a device for displaying an image or video on the device.

[0048] 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 adjusts one or more parameters of the light 108, such as amplitude or intensity, phase, polarization, pattern, direction, etc.

[0049] The light-emitting layer 104 can be any suitable lighting device. In these embodiments, the light-emitting layer 104 is printed, coated, or otherwise coupled to the substrate 102, and other arrangements of LEDs 110 can also be easily utilized, but it includes a plurality of light-emitting diodes (LEDs) 110 arranged in a matrix. As used herein, the LED 110 can be any suitable LED, such as a conventional LED, a quantum dot (QD) LED, and / or an organic LED (OLED).

[0050] The light conversion layer 106 is printed, coated, or otherwise coupled to the light-emitting layer 104 to adjust or otherwise convert (described in more detail later) the parameters of the light emitted from the light-emitting layer 104.

[0051] The light conversion layer 106 includes one or more light conversion units 122 arranged in a predetermined pattern, where each light conversion unit 122 includes a metasurface. As used herein, a metasurface is a two-dimensional array of nanostructures having subwavelength spacing and can be used to modulate electromagnetic waves. Details of the metasurface are described in the academic paper "LIGHT PROPAGATION WITH PHASE DISCONTINUITIES: GENERALIZED LAWS OF REFLECTION AND REFRACTION" by Nanfang Yu, Patrice Genevet, Mikhail A. Kats, Francesco Aieta, Jean-Philippe Tetienne, Federico Capasso, and Zeno Gaburro, Science volume 334, issue 6054, pages 333-337 (2011).

[0052] As shown in FIGS. 5 and 6, each metasurface unit 122 includes a metasurface having a sub-wavelength thickness (i.e., the sub-wavelength thickness is thinner than the wavelength of the light emitted from the light-emitting layer 104), and is periodically arranged in a specific order for precisely adjusting or converting the characteristics or parameters (such as, for example, amplitude or intensity, phase, polarization, pattern, direction, etc.) of the incident light. A plurality of nanostructures 124 are included, thereby enabling precise control of the characteristics of the light output therefrom.

[0053] In some embodiments, the nanostructures 124 (also referred to as "nanostructures") can be sub-wavelength structures made of a suitable metallic material or dielectric material having one or more dimensions smaller than the wavelength of the light emitted from the light-emitting layer 104. In some embodiments, the nanostructures 124 can include a plurality of nanorods (also referred to as "antennas", see FIG. 6). In some embodiments, the nanostructures 124 can include a plurality of V-shaped nanorods. As described above, the nanostructures 124 form a periodic or repeating pattern, and each pattern can include a plurality of nanostructures 124 of different shapes and dimensions.

[0054] Depending on the shape and distribution of the nanostructures 124, the light conversion layer 106 can be configured to adjust or convert one or more parameters of the incident light.

[0055] For example, as shown in FIG. 4, the metasurface unit 122A of the light conversion layer 106 phase-converts the incident light 108A and corrects the direction of the incident light 108A to converge, thereby forming a converging light beam that focuses at a desired point spaced apart from the light conversion layer 106.

[0056] As another example, the metasurface unit 122B of the light conversion layer 106 phase-converts the incident light 108B and corrects the direction of the incident light 108B to be parallel, thereby forming a parallel light beam to reach a distant target.

[0057] As a further example, the metasurface unit 122C of the light conversion layer 106 can be configured to phase-convert the incident light 108C and modify the direction of the incident light 108C to diverge, thereby forming a diverging light beam to illuminate a wide area.

[0058] In conventional grow light applications, one or more lighting devices (also referred to as grow light devices) are used to emit light towards plants to promote plant growth. In these applications, a portion of the light emitted from the grow light device, such as the light emitted from the peripheral region of the grow light device, only partially impinges on the plants due to the divergence of the light beam, whereby light energy can be wasted. Such a problem can be more severe when plants are arranged at intervals from each other.

[0059] In some embodiments, the light emitting device 100 can be used as a grow light device that does not have the above problems or at least reduces the above 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 towards the plants. For example, the light conversion layer 106 adjusts the light emitted from the peripheral region of the light emitting layer 104 towards the plants, while diverging the light emitted from the central region of the light emitting layer 104 to cover more areas of the plants, thereby being designed to produce significantly more efficient illumination.

[0060] In some embodiments, the light conversion layer 106 or at least some of its metasurface units 122 can be designed to optimize the lighting configuration for plants and adjust the parameters of the light emitted from the light emitting layer 104 to adapt to the growth requirements.

[0061] In some embodiments, the light conversion layer 106 or at least some of its metasurface units 122 can be adjusted to direct the light emitted from the light emitting layer 104 in a desired direction, thereby forming a high-concentration or low-concentration region, and thus can be designed to create a high-temperature or low-temperature spot in the target illumination region. Such high-temperature or low-temperature spots can be created to treat damaged areas of plants or to illuminate vulnerable parts of plants.

[0062] FIG. 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 the light emitting device 100 in the embodiments shown in FIGS. 3 and 4, except 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.

[0063] Moreover, in these embodiments, the light conversion layer 106 can be polarization selective. In particular, each metasurface unit 122 can select a specific polarization, that is, it can allow only light of a specific polarization state to pass through the metasurface unit 122 and block light of other polarization states. Different metasurface units 122 of the light conversion layer 106 can have the same or different polarization selection settings depending on the mounting mode.

[0064] The polarization control layer 202 is made of a suitable material that polarizes the incident light (represented by circular arrows 204 and 206 in FIG. 7) when the incident light travels through the polarization control layer 202. In some embodiments, the polarization control layer 202 can form a single polarization control unit to polarize the incident light into a predetermined polarization state.

[0065] In some other embodiments, the polarization control layer 202 can form a single polarization control unit and include a liquid crystal having a voltage-controlled phase difference. Therefore, the polarization of the polarization control layer 202 can be controlled by adjusting the voltage applied to the polarization control layer 202.

[0066] 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 crystal, and their polarization can be controlled by adjusting the voltage applied to the polarization control units.

[0067] Accordingly, the light conversion layer 106 exhibits a selective response to light in 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 the need to adjust a light source (e.g., the light emitting layer 102). The switched display or illumination pattern can be encoded in the polarization pattern and / or voltage pattern of the light conversion layer 106 for automatic pattern switching.

[0068] For example, in some embodiments, the light emitting device 200 can be used as a display, and the polarization control layer 202 and its light conversion layer 106 can each include a plurality of units that respectively form corresponding pixels 232 and 234 (see FIGS. 8A - 10B), where each pixel includes one or more sub-pixels.

[0069] In one embodiment shown in FIGS. 8A and 8B, each pixel 232 of the polarization control layer 202 includes a plurality of sub-pixels (e.g., two sub-pixels 242A and 242B). Accordingly, the polarization control layer 202 includes a plurality of sub-pixel sets (similarly identified using reference numerals 242A and 242B), where each set includes the respective sub-pixels 242A or 242B of each pixel 232. Each sub-pixel set is configured according to a specific polarization setting (see FIG. 8A).

[0070] As shown in FIG. 8B, each pixel 234 of the light conversion layer 106 has one metasurface sub-pixel (represented using reference numeral 234 as well) that is controlled to switch between two polarization selection and phase conversion settings (indicated by reference numeral 246).

[0071] During operation, the light-emitting layer 104 emits light (not shown). In a preferred polarization setting, each sub-pixel set of the polarization control layer 202 adjusts the light emitted from the light-emitting layer 104 to form two light beams (not shown) in different polarization states. The two light beams are superimposed and incident on the light conversion layer 106.

[0072] The metasurface sub-pixels 234 of the light conversion layer 106 are controlled to switch between two polarization selection and phase conversion settings 246 having a first polarization selection setting suitable for allowing the light beam from the first sub-pixel set 242A to pass through the metasurface sub-pixel 234 and a second polarization selection setting suitable for allowing the light beam from the second sub-pixel set 242B to pass through the metasurface sub-pixel 234. As a result, the light-emitting device 200 alternately displays two images 222 and 224 (see FIGS. 11A and 11B) in two directions. Depending on the phase conversion setting, the two directions can be two different directions as shown in FIGS. 11A and 11B, or the same direction.

[0073] The switching of the polarization selection and phase conversion settings of the light conversion layer 106 (also referred to as the refresh rate) can be a slow speed or low-frequency switching so as to clearly alternately display the two images 222 and 224, such as displaying the first image 222 at the first position for several seconds and then displaying the second image 224 at the second position for a further few seconds (FIGS. 11A and 11B). Alternatively, the refresh rate of the light conversion layer 106 can be high-frequency (e.g., 60 frames per second or more) so that the two images 222 and 224 are effectively simultaneously displayed to the human eye at two positions (see FIG. 12).

[0074] In one embodiment as shown in FIGS. 9A and 9B, each pixel 232 of the polarization control layer 202 has one metasurface sub-pixel (referring to FIG. 9A, indicated by reference numeral 248) that is controlled to switch between two polarization settings (also represented using reference numeral 232).

[0075] As shown in FIG. 9B, 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 sets (also identified using reference numerals 244A and 244B), each set including a respective sub-pixel 244A or 244B of each pixel 234. Each sub-pixel set is configured according to a specific polarization selection and phase conversion setting.

[0076] 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 so as to pass through the first sub-pixel set 244A of the light conversion layer 106 or the second sub-pixel set 244B of the light conversion layer 106, forming a light beam (not shown) with a switched polarization state. Depending on the refresh rate of the light conversion layer 106, the light emitting device 200 can alternately display two images 222 and 224 at two positions clearly or effectively simultaneously to the human eye (see FIGS. 11A, 11B, and 12).

[0077] In one embodiment shown in FIGS. 10A and 10B, 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 sets (also identified using reference numerals 242A and 242B), each set including a respective sub-pixel 242A or 242B of each pixel 232. Each sub-pixel set is configured according to a specific polarization setting (see FIG. 10A).

[0078] Correspondingly, as shown in FIG. 10B, 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 sets (also identified using reference numerals 244A and 244B), each set including the respective sub-pixels 244A or 244B of each pixel 234. Each sub-pixel set is configured according to a specific polarization selection and phase conversion setting. The polarization selection setting of each sub-pixel set 244A or 244B is consistent with (i.e., allows light from the corresponding sub-pixel 242A or 242B to pass through) the polarization setting of each sub-pixel set 242A or 242B.

[0079] During operation, the light emitting layer 104 emits light (not shown). Each sub-pixel set 242A or 242B of the polarization control layer 202 adjusts the light emitted from the light emitting layer 104 to form two light beams (not shown) in different polarization states. The two light beams are superimposed and incident on the light conversion layer 106. Each light beam from the polarization control layer 202 passes through the corresponding sub-pixel set 244A or 244B of the light conversion layer 106, thereby simultaneously forming two images 222 and 224 in two directions (see FIG. 12).

[0080] In some embodiments, the light emitting device 200 can be used as an illumination device that can rapidly switch between different illumination patterns. Moreover, the light emitting device 200 can be used as a grow light device having a customized polarization pattern that adapts to plants having highly regular components sensitive to light polarization. For example, some plants can absorb or reflect light in a specific polarization state significantly more efficiently than light in other polarization states. Thus, the light emitting device 200 can be used as a grow light device having a customized polarization pattern that adapts to the requirements of plants to optimize the photosynthesis process of the plants. The structure of the illumination device 200 in various embodiments can be the same as that shown in FIGS. 8A - 10B.

[0081] By using a metasurface in the light conversion layer 106, the lighting devices disclosed herein can efficiently couple light energy into an optical fiber 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 the light emitting device 100 in the embodiments shown in FIGS. 3 and 4, and 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 on the corresponding optical fiber cable 302. Such a lighting device 300 can be used in various applications such as efficient indoor lighting, locally optimized plant lighting, and efficient light energy distribution across a target area.

[0082] In the embodiment shown in FIG. 13, the light emitting device 300 is similar to the light emitting device 100 (i.e., having three layers 102, 104, and 106), but in some embodiments, the light emitting device 300 can be similar to the light emitting device 200 (i.e., having four layers 102, 104, 202, and 106).

[0083] In the above embodiments, the lighting devices 100, 200, or 300 include only one light conversion layer 106. In some embodiments, the lighting device can include a plurality of light conversion layers 106. In some embodiments, at least some of the plurality of light conversion layers 106 can be polarization selective, and different light conversion layers 106 can have the same or different polarization selection settings depending on the mounting configuration.

[0084] As described above, the various layers of the light emitting device 100, such as the light conversion layer 106, can be printed on the substrate 102 or on each other using any suitable printing technique.

[0085] For example, FIG. 14 is a conceptual diagram showing the printing of some layers such as the light conversion layer 106 and the light emitting layer 104 in some embodiments.

[0086] As shown, substrate 102 (with light-emitting layer 104 printed or otherwise attached thereon) is disposed on the flat surface of platform 342. A printing device (not shown) with slot die head 344 is used to print the sublayer / layer. Slot die head 344 includes ink cartridges 346 filled with respective “inks,” and moves over substrate 102 (or particularly printed light-emitting layer 104) to deposit the metasurface material from ink cartridges 346 onto substrate 102 (or light-emitting layer 104) to form one or more metasurface light conversion units 122 (as indicated by arrow 348).

[0087] As used herein, “ink” refers to a sublayer / layer material in a suitable form such as a solution, gel, or powder used as a precursor for layer fabrication. During slot die fabrication of each layer, heat treatment is typically used to evaporate the solvent or melt the powder to solidify the fabricated layer.

[0088] FIG. 15 is a schematic view 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, system 400 includes a power source 402 that supplies power to a control circuit 404, and a light-emitting device 406 that can be any of the light-emitting devices 100, 200, or 300 described above. Control circuit 404 controls light-emitting device 406 to emit light 408 having customizable parameters to illuminate plants 410 and promote the growth of plants 410.

[0089] FIG. 16 is a schematic view of a lighting system 500 for promoting the growth of plants according to some embodiments of the present disclosure. Lighting system 500 in these embodiments is similar to lighting system 400 shown in FIG. 14, and further includes a sensor 412 for monitoring the growth of plants 410, such as a light sensor for monitoring light 414 reflected from plants 410, and provides feedback to control circuit 404 for adjusting the light parameters as described above to optimize the lighting configuration and better promote the growth of plants 410.

[0090] 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 (also referred to as a “photovoltaic cell”) on the “back side” of the light-emitting layer 104 (i.e., between the substrate 102 and the light-emitting layer 104) for converting light energy into electrical energy, and a power conversion layer on the back side of the solar cell layer. Details of the solar cell layer and the power conversion layer are described in U.S. Provisional Patent Application No. 62 / 831,828, entitled “HYBRID-ENERGY APPARATUS, SYSTEM, AND METHOD THEREFOR,” filed by the present applicant, the content of which is hereby incorporated by reference in its entirety.

[0091] For example, FIG. 17 shows an example of a solar cell layer 540 including a plurality of sub-layers. As shown, the solar cell layer 500 in this example includes an anode sub-layer 542 made of a suitable material such as indium tin oxide (ITO), a zinc oxide (ZnO) sub-layer 544, a poly(ethyleneimine) and ethoxylated poly(ethyleneimine) (i.e., PEIE) sub-layer 546, an organic solar cell sub-layer 548 such as a sub-layer of a polymer solar cell including a sub-layer of a bulk heterojunction (BHJ), a molybdenum trioxide (MoO3) sub-layer 550, and a cathode sub-layer 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 a power converter layer.

[0092] Illumination system with controlled illumination pattern FIG. 18 shows a light-emitting device 600 in some embodiments that is used as an illumination source or light source with a controlled illumination pattern by precise control of the light deflection angle using a metasurface or other light control structure. The illumination from the illumination system 600 is distributed onto an image plane 612 according to a specific pattern, and one or more objects such as one or more plants are located within this image plane 612.

[0093] To facilitate the annotation, the x and y axes represent orthogonal axes that define the image plane 612, the z axis is an axis along the controllable illumination structure 100 and the image plane 612, and is orthogonal to the x and y axes (i.e., orthogonal to the image plane 612). The y deflection angle θ is the angle between the y axis and the projection of the light beam 610 on the image plane 612, and the z deflection angle φ is the angle between the z axis and the projection of the light beam 610 on the xz plane.

[0094] The light emitting device 600 is similar to the light emitting device 100 shown in FIG. 4 and includes a light emitting layer 104 having one or more LEDs (not shown) and, in these embodiments, a light conversion layer 106 such as a topocentric vector control panel (TVCP) layer on the front side of the light emitting layer 104. Although not shown in FIG. 18, the light emitting device 600 may also include a substrate 102 (similar to the light emitting device 100 shown in FIG. 4) for supporting the light emitting layer 104.

[0095] The light emitting layer 104 includes an array of LEDs as a light source and emits a plurality of light beams 610 that pass through the TVCP 106 and are directed toward the image plane 612.

[0096] The TVCP 106 includes one or more light conversion units 122 (also referred to as "lenses" in these embodiments and not shown in FIG. 18) arranged in a predetermined pattern, where each light conversion unit 122 includes a metasurface. Each light conversion unit 122 of the TVCP 106 controls the deflection angles θ and φ of the light beam 610 to adjust the azimuth angle, elevation angle, and angle of the light cone 610 within the image plane 612, thereby controlling the direction of the light beam 610 passing through the light conversion unit 122.

[0097] TVCP106 will effectively disrupt the symmetry of the light distribution that would otherwise exist on image plane 612 (see FIG. 2). Moreover, even a slight change in the deflection angles θ and φ will result in a significant change in the light intensity distribution on image plane 612. Therefore, using a carefully configured TVCP106, illumination system 600 can generate substantially all light intensity distributions within a target illumination area on image plane 612, as needed, using a plurality of light beams emitted from light-emitting layer 104 through TVCP106 towards a plurality of predetermined incident points distributed on image plane 612.

[0098] The illumination pattern (e.g., the size and shape of the target illumination area and the light intensity distribution within the target illumination area) and the number of light sources (e.g., LEDs) are determined using a suitable optimization method that optimizes a suitable cost function to determine the positions of the predetermined incident points such that all incident points must be located within the target illumination area.

[0099] For example, to obtain a uniformly distributed (or more precisely, approximately uniformly distributed) light intensity distribution, the normalized mean squared error (NMSE) of the light intensity distribution

Equation

[0100] FIG. 19 illustrates the formation of a cost function in an example where a uniform illumination pattern is generated within a circular target illumination area 622 on image plane 612. Those skilled in the art will recognize that cost functions for other illumination patterns can be formed in a similar manner.

[0101] In the example shown in FIG. 19, the illumination system 600 may use eight light beams emitted toward respective incident points 624 that are uniformly and angularly spaced on two concentric circles 626A and 626B (four points on each circle) within the circular region 622 of the image plane 612.

[0102] Any suitable optimization method, such as an artificial intelligence (AI) algorithm, a machine learning algorithm, a gradient descent (GD) method, and / or a simulated annealing (SA) method, may be used to find the global (or near-global) minimum value of the NMSE of Equation (1) and the corresponding deflection angles θ and φ of each light beam 610.

[0103] FIG. 20 shows, in the optimization, the following predetermined parameters: · The number of LEDs in the light-emitting layer 104, · The direction and angular spread of the field of view (FOV) of each LED, · The shape of the target illumination region on the image plane 612, · The size of the target illumination region, · The distance between the radiation source and the target illumination region, · The learning rate of GD, and · The maximum number of iterations is a flowchart showing the steps of a process 640 for finding the global (or near-global) minimum value of the NMSE of Equation (1) using the GD method with the above-described parameters.

[0104] Those skilled in the art will recognize that the parameters described above can be customized by the user before the start of process 640 or determined by the setup of system 600.

[0105] As shown in FIG. 20, after the start of process 640 (step 642), the parameters described above are incorporated (step 644), and an initial state of each light beam 610 (e.g., an initial set of values of the state variables (θ, φ)) is randomly selected (step 646).

[0106] In step 648, the gradient of the cost function in the current state with respect to the state variables (θ, φ) of all the optical beams 610 is calculated. Then, the state variables (θ, φ) of all the optical beams 610 are "moved" (i.e., the values of the state variables (θ, φ) are changed) in the reverse direction of the gradient value of the current state multiplied by the learning rate (step 650).

[0107] In step 652, process 640 checks whether the number of iterations has reached the maximum number of iterations (predetermined by the system or the user). If the number of iterations has reached the maximum number of iterations, the optimization is completed, and then process 640 ends (step 654).

[0108] In step 652, if the number of iterations has not reached the maximum number of iterations, process 640 proceeds to step 656 and checks whether the incident point of any of the optical beams 610 is outside the target illumination area. If not, process 640 returns to step 648 to further "move" the state variables (θ, φ) of the optical beams 610.

[0109] In step 656, if it is found that the incident point of one or more of the optical beams 610 is outside the target illumination area, process 640 recalculates the values of the state variables (θ, φ) of one or more of the optical beams 610 to position the incident point of the optical beams 610 on the boundary of the target illumination area along the reverse direction of the gradient value, and defines one or more of the optical beams as fixed beams (i.e., the state variables (θ, φ) of the optical beams are no longer used for optimization) (step 658). Then, process 640 randomly selects the initial state (e.g., a set of initial values of the state variables (θ, φ)) of each of the remaining optical beams 610 (step 660) and returns to step 648 for further optimization.

[0110] Process 640 may loop one or more times through the steps described above, and finally stop the trial according to the maximum number of iterations, and the global (or near-global) minimum value of NMSE is achieved. Next, the corresponding values of the state variables (θ, φ) of each optical beam 610 are used to configure the optical conversion unit 122 of TVCP106.

[0111] In some embodiments, the optimization process may divide the optical beams into a plurality of groups. For example, in the example shown in FIG. 19, the optimization process may divide the optical beams into two groups, each including four optical beams whose incident points are within circle 626A or 626B. Next, the optimization process may form a cost function in which the control variables for minimizing NMSE are the rotation radii and rotation degrees of circles 626A and 626B.

[0112] FIGS. 21 to 25 show the optimization results using the GD method for creating a uniform light intensity distribution within different-shaped target illumination regions on the image plane, including a triangular illumination region (FIG. 21), a square illumination region (FIG. 22), a pentagonal illumination region (FIG. 23), a circular illumination region (FIG. 24), and a donut-shaped or ring-shaped illumination region (FIG. 25).

[0113] Fabrication technology of the metasurface The metasurface-based TVCP106 can be fabricated using any suitable method such as electron beam lithography. However, this technology is costly and time-consuming and is only suitable for fabricating small metasurfaces. Since the TVCP106 described above typically requires a metasurface with a centimeter-scale diameter, conventional electron beam lithography technology may not be fast and cost-effective.

[0114] In some embodiments, deep ultraviolet (UV) lithography technology is used to fabricate metasurfaces such as the metasurface-based TVCP106 described above. Deep ultraviolet lithography technology is a well-established technology used in the semiconductor field, but to the applicant's knowledge, it has not been used for fabricating metasurfaces.

[0115] In this technique, a chromium layer is deposited on a glass wafer. Subsequently, the wafer is spin-coated with a resist, followed by UV exposure and development. Finally, the meta-surface pattern is defined by etching the chromium layer. Such a technique enables the fabrication of multiple meta-surfaces on a large wafer through a single process, thereby resulting in a rapid and cost-effective fabrication. Moreover, deep ultraviolet lithography technology also enables the fabrication of meta-surfaces for the visible and infrared wavelength ranges using silica, titanium dioxide, or amorphous silicon.

[0116] Illumination system having a uniform illumination pattern As described above, conventional illumination systems such as LED panels used for growing indoor plants typically do not provide uniform light distribution across the entire plant.

[0117] In some embodiments similar to the embodiments shown in FIGS. 4 and 18, uniform or substantially uniform illumination of an illumination system 700, such as a grow light system, can be obtained by superimposing an angle control light conversion layer 106, such as a TVCP layer, on the front side of a light emitting layer 104. As shown in FIG. 26, the light emitting layer 104 emits a plurality of light beams 702 that pass through the TVCP 106 and are directed towards an image plane (not shown). The spatial distribution of each light beam 702 can be characterized by angles β, θ, and φ, where angle β determines the angular spread of the light beam 702, and angles θ and φ determine the direction of the light beam 702.

[0118] The TVCP106 includes one or more optical conversion units 122 arranged in a predetermined pattern, where each optical conversion unit 122 includes a metasurface. Each optical conversion unit 122 of the TVCP106 is configured to accurately control the angles β, θ, and φ of the corresponding optical beam 702 in order to arbitrarily change the angular range, altitude, and latitude of the light cone in the image plane. The TVCP106 would otherwise effectively lose the symmetry of the light distribution that would otherwise exist in the image plane (see, for example, FIG. 2). The use of the TVCP106 is effective in that a slight change in the angles β, θ, and / or φ can result in a significant difference in the intensity distribution in the image plane. Thus, almost any arbitrary intensity distribution can be generated.

[0119] The lighting system 700 can be used to generate a uniform illumination pattern in the image plane and can be used as a glow light. Note that it is necessary to minimize the number of metasurfaces with different designs to facilitate fabrication and implementation.

[0120] In some embodiments, the TVCP106 of the uniform lighting system 700 can include only two types of metasurfaces, a set of split metasurfaces and a set of converging metasurfaces.

[0121] The split metasurface is a polarization-sensitive metasurface that modifies the angles β, θ, φ of the optical beam by guiding light in two orthogonal polarization states in exactly opposite directions. In these embodiments, the light-emitting layer 104 (e.g., an LED light-emitting layer) emits unpolarized light, ensuring that the power is equally split in two exactly opposite directions at the split metasurface.

[0122] As shown in FIG. 27A, the split metasurfaces 122A and of the TVCP106 are configured to distribute the optical beams 702A and 702B, respectively, at the boundary of the target illumination pattern on the image plane (not shown).

[0123] FIG. 27B shows an illumination pattern 704A on an image plane having significantly distributed light energy along a vertical boundary (hereinafter, the directional light is referred to as "vertically boundary focused light") created by using a split metasurface to split the light from the light emitting layer and direct the light in a direction perpendicular to the corresponding boundary.

[0124] Similarly, FIG. 27C shows an illumination pattern 704B on an image plane having significantly distributed light energy along a horizontal boundary (hereinafter, the directional light is referred to as "horizontally boundary focused light") created by using a split metasurface rotated 90° (similar to the split metasurface used in FIG. 27B but having a 90° rotated light energy distribution) to split the light from the light emitting layer and direct the light in a horizontal direction to the corresponding boundary.

[0125] The horizontally / vertically boundary focused light as shown in FIG. 27B can be directed to the same target area on the image plane such that the guided light overlaps to form an illumination pattern 706 having light energy concentrated substantially along four boundaries of the area (see the conceptual diagram of FIG. 28).

[0126] As shown in FIGS. 29A and 29B, the converging metasurface 122C is configured to modify the angle β of the light beam 702C without changing the direction of the cone of the light beam 702C. Thus, the converging metasurface 122C distributes the light beam 702C to the center of the target area on the image plane, thereby creating an illumination pattern using the light energy substantially focused at the center of the target area.

[0127] As illustrated by the conceptual diagram shown in FIG. 30, by using the split metasurfaces 122A and 122B and the converging metasurface 122C to direct the light beams to the same target area, the illumination patterns 706 (a combination of the illumination patterns 704A and 704B shown in FIG. 28) and 708 can be combined to obtain a uniform light distribution within the target area.

[0128] Such uniform light distribution is substantially independent of the distance between the meta - surface - based TVCP106 and the image plane 712. As shown in FIG. 31, the light distribution is simply scaled up and down by different distances without sacrificing the uniformity of the distribution.

[0129] FIG. 32 shows an exemplary implementation of the TVCP106 using an array of meta - surfaces 122. For ease of illustration, only two meta - surfaces 122 are shown.

[0130] In these embodiments, the TVCP106 includes a meta - surface housing 722 that covers the LED 110 mounted on a printed circuit board (PCB) 724 of the light - emitting layer 104. The meta - surface housing 722 includes a plurality of receiving portions 726 at positions corresponding to the LED 110. Each receiving portion 726 includes an inner opening for receiving light emitted from the light - emitting layer 104 and an outer opening for passing the received light, and includes an inwardly - spreading inner surface having an outer opening with an area larger than the area of the inner opening.

[0131] In these embodiments, the inner surface of the receiving portion 726 is reflective to reflect light rays (emitted from the LED 110 within the receiving portion 726) at high angles so as to contribute to the overall illumination, thereby increasing the efficiency of the overall illumination. The maximum light throughput is achieved when the cross - section of the inner surface is parabolic in shape and the LED is located at the center of the inner surface. FIG. 33 is a photograph showing the meta - surface housing 722 coupled to the light - emitting layer 104.

[0132] The plurality of meta - surface units 122 are fixed or otherwise coupled to the receiving portions 726 of the meta - surface housing 722 using suitable fastening means such as epoxy and / or adhesive, thereby ensuring the alignment of the LED 110 and the meta - surface units 122.

[0133] Polarization - selective illumination Plants are often composed of components with an ordered arrangement. As a result, the light absorption of plants is often sensitive to polarization. In other words, plants can absorb more light in a specific polarization state than in other polarization states. Therefore, photosynthesis can be optimized using illumination in a specific polarization state.

[0134] In some embodiments, the metasurface-based light conversion layer 106 of the glow light disclosed herein can be polarization selective, and this light conversion layer 106 can be implemented by arranging the nanoscale structure 124 of the metasurface to have an asymmetric base shape 732 as shown in FIG. 34. Therefore, a glow light provided with such a metasurface-based light conversion layer 106 can be used to illuminate plants with light in a specific polarization state in order to optimize the light for photosynthesis. Generally, the metasurface of the light conversion layer 106 can be designed to illuminate plants in various polarization states including linearly polarized states, circularly polarized states, and generally elliptically polarized states. Linearly polarized illumination can be used to optimize the photosynthesis of plants composed of fibers oriented in a specific direction, and circularly polarized illumination can be used to optimize the photosynthesis of plants composed of components having a helical structure.

[0135] Metasurface-based TVCP for a photovoltaic cell In solar cells, although always desirable, complete light absorption by the photovoltaic cells of the solar 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, the light reflection 842 generated at the surface of the photovoltaic cell 844 also causes a loss of solar energy that could otherwise be absorbed by the photovoltaic cell 844.

[0136] In some embodiments, the metasurface-based TVCP can be incorporated, for example, into a photovoltaic panel having one or more silicon-based and / or one or more quantum dot photovoltaic cells, in which the metasurface-based TVCP can be configured to effectively send light of a specific wavelength to the photovoltaic cell. Moreover, the metasurface-based TVCP enables a significant reduction in the size of the photovoltaic panel.

[0137] As will be appreciated by those skilled in the art, the metasurface includes nanoscale structures. The shape and distribution of the nanoscale structures of the metasurface can be designed or otherwise configured to meet the requirements of a particular application. For example, the metasurface can be designed to pass or otherwise transmit a portion of the incident light of the target spectrum through the metasurface and to completely reflect other portions of the incident light from the target spectrum.

[0138] In some embodiments shown in FIG. 36, the metasurface-based TVCP 106 can be disposed, for example, on the front side of a photovoltaic panel 852 having 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. Thus, when the photovoltaic panel 852 is used alone, a spectrum that is not fully absorbed may turn into heat, and the performance of the photovoltaic panel 852 may be degraded by other undesirable effects. Therefore, the combination of the metasurface-based TVCP 106 and the photovoltaic panel 852 is significantly more efficient compared to the photovoltaic panel 852 alone. Such an arrangement or combination is particularly important for indoor photovoltaic cells that collect light energy from artificial light sources such as LEDs, in which the metasurface units can be designed to match the specific illumination spectrum of the light source and reject other light that cannot be efficiently absorbed by the photovoltaic cell.

[0139] Another important use of the metasurface lies in the ability described above to redirect light rays in another direction. As shown in FIG. 37, the metasurface-based TVCP106 on the front side is a photovoltaic panel 852, and the metasurface-based TVCP106 is configured to converge the incident light rays 854 onto a small area of the photovoltaic panel 852, and thus the size of the photovoltaic panel 852 can be significantly reduced, and it can be the photovoltaic panel 852. FIG. 38 shows a prior art photovoltaic panel 844 without the metasurface-based TVCP106 for comparison.

[0140] Ultra-Directional Screen Using Metasurface Conventional screens or displays typically have a wide angular spread in their field of view (FOV). However, in some applications, it may be desirable to limit the FOV of the display.

[0141] As used herein, the term FOV refers to the angular range of illumination (e.g., conical or other shape) emitted from a component (e.g., LED layer, metasurface layer, etc.), and in various embodiments, the light can be used for illumination or to display one or more images. The FOV can be characterized by the direction of the light emitted from the component and the three-dimensional (3D) angular spread.

[0142] For example, displays in vehicles or airplanes are generally only viewed by individuals. However, as shown in FIG. 39, a display 862 having a wide FOV 868 (i.e., an FOV 868 having a wide angular spread) within a vehicle or airplane (not shown) emits light into the surrounding area unnecessarily, resulting in a decrease in brightness to the user 864 in front of the display 862, waste of light energy, and interference to the person 866 adjacent to the user 864.

[0143] Similarly, a display with a wide FOV used in a home or theater will illuminate surrounding areas such as walls and ceilings, leading to a reduction in brightness to the user in front of the display and waste of light energy.

[0144] Moreover, in some applications that require enhanced security or privacy, such as the display of an ATM, the display within a bank, or the display of a laptop computer used by a user for highly confidential work, the wide FOV displays in these applications can cause security or privacy risks in addition to the brightness reduction problems, waste of light energy, and / or interference to adjacent people described above. Therefore, a highly directional display may be required.

[0145] FIG. 40 shows a meta-surface-based super-directional screen or display 870 according to some embodiments of the present disclosure. The super-directional screen 870 includes a display or display layer 872 and a meta-surface panel or layer 874 on the front side thereof.

[0146] Similar to the light conversion layer 106 described above, the meta-surface panel 874 guides the light emitted from the display 872 in a desired direction so as to limit the light within a predetermined FOV 878 that is smaller than the FOV 876 of the display 872, thereby creating a virtual visual barrier so that only the intended viewer 864 can view the content shown on the display 872. The meta-surface panel 874 includes a plurality of meta-surface units constructed of an array of nano-scale structures.

[0147] This super-directional screen 870 has · excellent brightness due to the concentrated distribution of light energy in a smaller area, · improved power efficiency due to the avoidance of illumination in non-target areas and the uniform distribution of light energy in the target area, and · enhanced security and privacy as visual information that can only be viewed by the viewer in front of the super-directional screen 870 and has many advantages.

[0148] As described above, the metasurface can be designed to interact with light in different polarization states in different manners, which is achieved by fabricating a nanostructure of the metasurface with an asymmetric shape.

[0149] FIG. 41 shows a variable field of view (VFOV) screen or display 880 in some embodiments. The MFOV display 880 includes a display 872, a polarization control panel 884 on the front side of the display 872, and a polarization sensing metasurface panel 886 on the front side of the polarization control panel 884.

[0150] In these embodiments, the polarization control panel 884 can be implemented using a liquid crystal polarizer rotator and is controlled by an adjustable control signal V for controlling the polarization of the light emitted from the display 872 to either one of two orthogonal polarization states.

[0151] The MFOV display 880 is similar to the light emitting device or display 200 shown in FIGS. 11A and 11B, but the MFOV display 880 in these embodiments does not direct light in different polarization states to FOVs in different directions as the light emitting device or display 200 shown in FIGS. 11A and 11B does. Rather, the polarization sensing metasurface panel 886 in these embodiments interacts with the polarized light to direct the light in the first polarization state to a first FOV having a first angular spread 888 and to direct the light in the second polarization state to form a second FOV having a second angular spread 890. For example, the first angular spread 888 can be a wide angular spread suitable for a plurality of users 864 and 866 with respect to the MFOV display 880 for viewing the display content, and the second angular spread 890 can be a narrow angular spread smaller than the first angular spread 888 for enabling only the user 864 to view the display content.

[0152] In the above embodiment, when the control signal is at the first voltage, the polarization control panel 884 polarizes all the light passing through the polarization control panel 884 into the first polarization state, and when the control signal is at the second voltage, all the light passing through the polarization control panel 884 is polarized into the second polarization state. In this way, the user 864 can switch the FOV of the MFOV display 880 between the first angular spread and the second angular spread, respectively, for sharing the display content with adjacent people and for creating a virtual visual barrier to prevent other people from viewing the display content.

[0153] In another embodiment shown in FIG. 42, the MFOV display 880 is similar to the display described in FIGS. 10A and 10B. Specifically, the display 872 includes two sets of units (pixels or sub-pixels depending on the design) that can be used for each set of the unit to display an image.

[0154] Correspondingly, each of the polarization control panel 884 and the polarization sensing metasurface panel 886 also includes two sets of units corresponding to the two sets of units of the display 872. Each set of units of the polarization control panel 884 is controlled by a separate control signal V1 or V2, and each set of units of the polarization sensing metasurface panel 886 corresponds to a specific polarization state and guides the light of the polarization state to a specific FOV.

[0155] Therefore, the display 872 can simultaneously display two images using two sets of pixels / units, and the polarization control panel 884 polarizes the light of the first image and the second image into the first polarization state and the second polarization state. Next, the polarization sensing metasurface panel 886 guides the light in the first polarization state (i.e., the first image) to a first FOV having a wide angular spread for sharing the first image with a plurality of people 864 and 866, and guides the light in the second polarization state to a second FOV having a narrow angular spread for preventing the person 866 from viewing the second image.

[0156] For example, as shown in FIGS. 43A and 43B, the display simultaneously displays two images 892A and 892B, where image 892A is displayed within a first FOV with a wide angular spread and image 892B is displayed within a second FOV with a narrow angular spread.

[0157] As shown in FIG. 43C, display 872 divides pixels among a first set of pixels 894A and a second set of pixels 894B that are arranged side by side to simultaneously and side-by-side display images 892A and 892B.

[0158] As shown in FIG. 43D, polarization control panel 884 includes a plurality of polarization units 894 corresponding to the pixels of display 872, including a first set of polarization units 896A corresponding to the first set of pixels 894A for polarizing the light passing therethrough into a first polarization state and a second set of polarization units 896B corresponding to the second set of pixels 894B for polarizing the light passing therethrough into a second polarization state.

[0159] As shown in FIG. 43E, polarization sensing metasurface panel 886 includes a plurality of metasurface units 898 corresponding to the polarization units 894 of polarization control panel 884, where the light in the first polarization state passing through metasurface unit 898 is directed to a first FOV (having a wide angular spread) and the light in the second polarization state passing through metasurface unit 898 is directed to a second FOV (having a narrow angular spread).

[0160] As a result, the first image 892A is directed to the first FOV and the second image 892B is directed to the second FOV. As shown in FIG. 43F, images 892A and 892B are visible to user 864 located in both the first FOV and the second FOV, and user 866 located only in the first FOV (having a wide angular spread) can only view the first image 892A. In other words, image 892B is not visible to user 866 located only in the first FOV.

[0161] 3D Display Using a Meta-Surface FIG. 44 shows a 3D display 900 using a meta-surface according to some embodiments of the present disclosure. As shown, the 3D display 900 includes a display 872 and a polarization-sensing meta-surface panel 886 on the front side of the display 872. The display 872 displays an image by emitting unpolarized light (generally including both polarization states). The polarization-sensing meta-surface panel 886 is configured to direct light in a first polarization state to a first FOV 888 and light in a second polarization state to a second FOV 890 that is slightly laterally displaced from the first FOV 888. A user 864 wearing glasses having lenses that polarize light in different polarization states views a first image with one eye and a second image with the other eye, and the second image has a slight perspective distortion from the first image, thereby generating a 3D perception of the displayed image.

[0162] In some embodiments, the 3D display 900 may also include a polarization control panel 884 sandwiched between the display 872 and the polarization-sensing meta-surface panel 886. The polarization control panel 884 alternately polarizes light from the display 872 into a first polarization state and a second polarization state during operation.

[0163] FIG. 45 shows a 3D display 920 using a meta-surface according to some embodiments of the present disclosure. The 3D display 920 is similar to that shown in FIG. 44. However, the polarization-sensing meta-surface panel 886 is configured to direct light in a first polarization state to a first FOV 888 that covers only the first eye of the user 864 and light in a second polarization state to a second FOV 890 that covers only the second eye of the user 864. Thus, a user 864 not wearing glasses having polarization lenses can view a first image with one eye and a second image with the other eye, and the second image has a slight perspective distortion from the first image, thereby generating a 3D perception of the displayed image.

[0164] In some embodiments, the 3D display 920 may also include a polarization control panel 884 sandwiched between the display 872 and the polarization sensing metasurface panel 886. The polarization control panel 884 alternately polarizes the light from the display 872 into a first polarization state and a second polarization state during operation.

[0165] Solar cell angle correction In the prior art, solar panels may face the problem of sunlight reflection.

[0166] As will be understood by those skilled in the art, the incident angle of sunlight can have a significant impact on the efficiency of a photovoltaic cell. As shown in FIG. 46, the photovoltaic cells of the solar panel 942 are most efficient when sunlight 944 impinges perpendicularly on the photovoltaic cells.

[0167] As shown in FIG. 47, at different times when sunlight 944 makes an angle other than perpendicular to the photovoltaic cells of the solar panel 942, a portion 946 of the sunlight is reflected and the efficiency of the photovoltaic cells decreases. Thus, the photovoltaic cells of a fixed solar panel will have different efficiencies at different times of the day and on different days of the year. Although solar tracking systems are used to improve the efficiency of photovoltaic panels by rotating the solar panels to track the sun, such systems require a tracking system and moving parts, and the cost of manufacturing and using such systems is high.

[0168] FIGS. 48 and 49 show a solar energy collection device 970 including a solar panel 972 having one or more photovoltaic cells and a plurality of TVCPs 974 on its front side. By using an embedded polarization control panel and a polarization sensing metasurface whose response can vary for each TVCP 974, the plurality of TVCPs 974 can change the direction of sunlight 944 such that when sunlight 944 within a predetermined range of incident angles impinges on the solar panel 972, it becomes perpendicular to the photovoltaic cells, thereby improving the efficiency without the need for a solar tracking system or moving parts.

[0169] In some of the embodiments described above, the light-emitting device and / or system is used for plant growth, such as the growth of indoor or outdoor plants. However, those skilled in the art will recognize that the light-emitting device and / or system disclosed herein can alternatively be used for other applications such as streetlights.

[0170] Although the embodiments have been described above with reference to the accompanying drawings, those skilled in the art will recognize that modifications and variations can be made without departing from the scope of the invention as defined by the appended claims.

Claims

1. A light-emitting device, comprising: a light-emitting layer for emitting light; a light conversion layer coupled to the light-emitting layer, the light conversion layer including one or more light conversion units, each light conversion unit including a metasurface for adjusting one or more parameters of the light emitted from the light-emitting layer; and a light-emitting device including the same.

2. The light-emitting device according to claim 1, wherein the light-emitting layer includes one or more light-emitting diodes (LEDs) for emitting light.

3. The light-emitting device according to claim 1 or 2, wherein the light conversion layer is printed on the light-emitting layer.

4. The light-emitting layer includes one or more light-emitting units, the light conversion layer includes a housing including one or more receiving portions for receiving the one or more metasurfaces, and the one or more receiving portions are located at positions corresponding to the positions of the one or more light-emitting units to align the one or more metasurfaces with the one or more light-emitting units. The light-emitting device according to claim 1 or 2.

5. Each of the one or more receiving portions includes an inner opening for receiving light emitted from the light-emitting layer and an outer opening for allowing the received light to pass therethrough, and includes an inner surface that expands outward. The outer opening has an area larger than the area of the inner opening. The light-emitting device according to claim 4.

6. The light-emitting device according to claim 5, wherein the inner surface of each of the one or more receiving portions is reflective.

7. The light-emitting device according to claim 5 or 6, wherein a cross section of the inner surface of each of the one or more receiving portions has a parabolic shape.

8. A light-emitting device, comprising: a light-emitting layer for emitting light; a light conversion layer including one or more light conversion units, each light conversion unit including a metasurface, and at least one metasurface being polarization-selective for selectively passing the light emitted from the light-emitting layer having a predetermined polarization state through the metasurface; and a light-emitting device including the same.

9. The light-emitting device according to claim 8, wherein each of the one or more metasurfaces includes a plurality of nanostructure arranged in an asymmetric base shape.

10. The light-emitting device according to claim 8 or 9, further including a polarization control layer sandwiched between the light-emitting layer and the light conversion layer for polarizing the light emitted from the light-emitting layer.

11. The light-emitting device according to claim 8 or 10, which is gro-lite for promoting the growth of one or more plants.

12. A light-emitting device for promoting the growth of one or more plants, comprising: a light-emitting layer for emitting light; 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 the light emitted from the light-emitting layer to optimize the illumination configuration of the one or more plants, at least one light conversion layer; A light-emitting device comprising:

13. A display device, comprising: a light-emitting layer for emitting light; 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 the light emitted from the light-emitting layer to display one or more images, at least one light conversion layer; A display device comprising:

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; at least one light conversion layer coupled to the polarization control layer, including one or more light conversion units, each light conversion unit including at least one metasurface, and at least one metasurface being polarization selective to selectively pass the polarized light from the polarization control layer through the metasurface for switching between different illumination patterns or images, at least one light conversion layer; A light-emitting device comprising:

15. 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; at least one light conversion layer coupled to the polarization control layer, including one or more light conversion units, each light conversion unit including at least one metasurface, and at least one metasurface being polarization selective to selectively pass the polarized light from the polarization control layer through the metasurface to create a plurality of different illumination patterns or images at different positions, at least one light conversion layer; A light-emitting device comprising:

16. A light-emitting device, comprising: a light-emitting layer for emitting light toward a radiation source field of view (FOV); At least one meta - surface layer on the front side of the light - emitting layer for guiding the light emitted from the light - emitting layer toward a first FOV having an angular spread smaller than the angular spread of the radiation source FOV, and A light - emitting device including the same. **Claim 17** Further including a polarization control layer sandwiched between the light - emitting layer and the at least one light - conversion layer, The polarization control layer is configured to polarize the light emitted from the light - emitting layer into a first polarization state or a second polarization state in response to a control signal, The at least one light - conversion layer is configured to guide the light from the polarization control layer in the first polarization state toward a first FOV having an angular spread smaller than the angular spread of the radiation source FOV, and to guide the light from the polarization control layer in the second polarization state toward a second FOV having an angular spread larger than the angular spread of the first FOV. The light - emitting device according to claim 16. **Claim 18** A light - emitting device, comprising A light - emitting layer for emitting light, and A light - conversion layer on the front side of the light - emitting layer, including a plurality of light - conversion units, each light - conversion unit including a meta - surface for guiding the light emitted from the light - emitting layer toward a target region to form a predetermined light - distribution pattern. A light - emitting device including the same. **Claim 19** The predetermined light - distribution pattern is a substantially uniform light - energy distribution on the target region. The light - emitting device according to claim 18. **Claim 20** The plurality of meta - surfaces include a first set of meta - surfaces for guiding the light emitted from the light - emitting layer toward the boundary of the target region, and a second set of meta - surfaces for guiding the light emitted from the light - emitting layer toward the center of the target region to generate the substantially uniform light - energy distribution on the target region. The light - emitting device according to claim 19. **Claim 21** A solar - energy collection device, comprising A photovoltaic layer having a plurality of photovoltaic cells, and At least one meta - surface layer on the front side of the photovoltaic layer for substantially guiding light to the photovoltaic layer without causing reflection in the photovoltaic layer. A solar - energy collection device including the same. **Claim 22** Including a plurality of meta - surface layers for guiding light at an incident angle within a predetermined range so as to impinge perpendicularly on the photovoltaic layer. The solar - energy collection device according to claim 21. **Claim 23** A light - emitting device, comprising A light - emitting layer for emitting light, and At least one metasurface layer on the front side of the light-emitting layer for guiding the light emitted from the light-emitting layer in the first polarization state toward the first FOV and guiding the light emitted from the light-emitting layer in the second polarization state toward the second FOV The light-emitting device includes, and the first FOV and the second FOV are superimposed to form a three-dimensional (3D) perception for a user wearing glasses having lenses with different polarization states, and are laterally shifted from each other. **Claim 24** A light-emitting device, A light-emitting layer for emitting light, At least one metasurface layer on the front side of the light-emitting layer for guiding the light emitted from the light-emitting layer in the first polarization state toward the first FOV and guiding the light emitted from the light-emitting layer in the second polarization state toward the second FOV The light-emitting device includes, and the first FOV and the second FOV are laterally shifted from each other such that the first FOV is visible only by the first eye of the user at a predetermined distance and the second FOV is visible only by the second eye of the user at the predetermined distance in order to form a 3D perception for the user.

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