Micro-LED collimation system based on metasurface

Abstract

The utility model relates to a Micro-LED collimation system based on a metasurface, and belongs to the field of optical elements, the Micro-LED collimation system based on the metasurface comprises a Micro-LED and the metasurface, the metasurface is composed of a medium optical filter and a collimation super lens, the collimation super lens is arranged at the downstream of the medium optical filter, and the collimation super lens is composed of a substrate, a microstructure and a protection layer. According to the invention, crosstalk between the Micro-LED adjacent arrays is reduced through the angle optical filter, light with a small angle is collected into the super lens, and stray light forming crosstalk can be filtered at the same time. And the light with a smaller angle can be further collimated through the super lens, so that a better result can be obtained.

Description

Technical Field

[0001] This application belongs to the field of optical components, and specifically relates to a Micro-LED collimation system based on metasurfaces. Background Technology

[0002] With the introduction of the "metaverse" concept, the XR field has experienced rapid development. Because the displays in XR components are extremely close to the human eye, high resolution is required for the flat panel displays used. Micro-LED arrays, due to their high brightness, small size, and long lifespan, have significant application value in the XR field. However, Micro-LEDs have a large emission angle and close proximity of adjacent pixels. Due to limitations in processing capabilities, it is difficult to align Micro-LEDs to a small angle using curved microlens arrays, thus limiting the performance of Micro-LED display devices.

[0003] Metasurfaces, as a novel beam control element, can precisely control incident beams at the subwavelength scale. These ultrathin beam control devices make collimation of Micro-LEDs possible. However, crosstalk between light sources still exists in metasurface-based LED collimating elements, affecting their performance. Utility Model Content

[0004] This application provides a Micro-LED collimation system based on metasurfaces to at least solve the above-mentioned technical problems existing in the prior art.

[0005] This application provides a Micro-LED collimation system based on a metasurface, including a Micro-LED and a metasurface. The metasurface is composed of a dielectric filter and a collimating superlens. The collimating superlens is located downstream of the dielectric filter and is composed of three layers: a substrate, a microstructure, and a protective layer.

[0006] In one embodiment, the dielectric filter is an angle filter composed of multiple dielectric films.

[0007] In one embodiment, the angle filter has a specific filter angle θc, where θc < 50°.

[0008] In one possible implementation, θc is 10°, 20°, or 35°.

[0009] In one embodiment, the substrate, microstructure, and protective layer are all materials transparent to the designed wavelength, and their refractive indices are related as follows: n 基底 ≤n 保护层 <n 微结构 .

[0010] In one implementation, the phase is adjusted by changing the geometric dimensions of the microstructure, thereby achieving control within the 0-2π range.

[0011] In one embodiment, the Micro-LED operates at a visible or near-infrared wavelength, with a wavelength range of 400 nm to 1000 nm.

[0012] In one embodiment, the wavelength is 405nm, 550nm, 632nm, 850nm or 940nm.

[0013] Compared with the prior art, this application has the following advantages:

[0014] Crosstalk between adjacent arrays of Micro-LEDs is reduced by using a dielectric filter, which collects light at smaller angles into the superlens while filtering out stray light that causes crosstalk. The superlens then further collimates the light at smaller angles, resulting in better performance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the Micro-LED collimation system in the embodiments of this application;

[0016] Figure 2 This is a schematic diagram of the metasurface structure in an embodiment of this application;

[0017] Figure 3 This is a schematic diagram of the structure of the dielectric filter in the embodiments of this application;

[0018] Figure 4 This is a schematic diagram of the filtering performance of the dielectric filter in the embodiments of this application;

[0019] Figure 5 This is a schematic diagram of the microstructure in the embodiments of this application;

[0020] Figure 6 This is a schematic diagram illustrating the relationship between microstructure geometry and phase delay and transmittance in the embodiments of this application;

[0021] Figure 7 This is a schematic diagram of the light intensity angular distribution of Micro-LED without the addition of a collimating metasurface in the embodiments of this application;

[0022] Figure 8 This is a schematic diagram of the collimation performance after adding a dielectric filter in an embodiment of this application;

[0023] Figure 9 This is a schematic diagram of the collimation performance after the complete collimation metasurface in the embodiments of this application;

[0024] Figure 10This is a schematic diagram of the intensity spatial distribution of the Micro-LED array after collimation in an embodiment of this application. Detailed Implementation

[0025] The present application will now be described in further detail with reference to the accompanying drawings.

[0026] In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0027] refer to Figure 1 This application provides a Micro-LED collimation system based on a metasurface, including a Micro-LED and a metasurface. The light emitted by each pixel of the Micro-LED is collimated into an approximately parallel beam after passing through the metasurface.

[0028] Micro-LEDs operate in the visible or near-infrared range, with wavelengths ranging from 400nm to 1000nm. Specifically, wavelengths can be 405nm, 550nm, 632nm, 850nm, 940nm, etc.

[0029] Figure 2 A metasurface for collimation of Micro-LEDs is presented, which consists of a dielectric filter and a superlens.

[0030] Figure 3 A dielectric filter structure is presented, consisting of two different structures stacked alternately, each layer having a different thickness, to achieve filtering at different angles. The results are as follows: Figure 4 As shown, light with an incident angle of less than 35° can pass through the filter with high transmittance. When the incident angle is greater than 35°, due to the nature of the multilayer film, it will exhibit low transmittance. This multilayer dielectric film can perform preliminary filtering of the emitted beam of Micro-LEDs to avoid crosstalk.

[0031] The metasurface consists of a dielectric filter and a collimating superlens, with the collimating superlens positioned downstream of the dielectric filter.

[0032] A dielectric filter is an angle filter composed of multiple dielectric films. This filter is made of at least one material and has a specific filtering angle θc, which can be any value less than 50°, such as 10°, 20°, or 35°. When the angle of incidence is less than θc, the light passes through directly; however, when the angle of incidence is greater than θc, the incident light will be reflected and will not enter the subsequent collimation section.

[0033] Figure 5 A schematic diagram of the microstructure unit of the superlens is given. The collimating superlens consists of three layers: a substrate, a microstructure, and a protective layer. The size P of the substrate needs to be smaller than the wavelength of the incident light.

[0034] The substrate, microstructure, and protective layer are all made of materials transparent to the designed wavelength, and their refractive indices are related as follows: n 基底 ≤n 保护层 <n 微结构 Different phase delays and transmittances can be obtained by changing the geometric dimensions d of the microstructure. Based on this enantiomeric relationship, an atomic library is established, and some results from the atomic library are shown below. Figure 6 As shown. Note that in practical applications, the use of microstructures with low transmittance should be avoided as much as possible.

[0035] By optimizing the lens using techniques such as ray tracing, a phase distribution that can collimate the Micro-LED is obtained. The phase delay in the atom library is then matched with this phase distribution. The matching needs to ensure that the calculated phase distribution is as close as possible to the phase delay in the parameter library, while also maintaining high transmittance. This method can be described by the following formula:

[0036]

[0037] In the formula, α and β are weighting coefficients. To design the required phase distribution, and T real The phase delay and transmittance provided by the atomic pool energy.

[0038] By combining a dielectric filter and a superlens, crosstalk-free collimation of a Micro-LED array can be achieved. The result is as follows: Figure 7-10 As shown. Figure 7 The divergence of Micro-LEDs without the collimating metasurface is presented, with a divergence angle of ±90°. Figure 8 The beam divergence of the Micro-LED array with only a dielectric filter is shown. It can be found that after filtering with a dielectric filter, the divergence angle of the Micro-LED array is reduced from ±90° to ±30°. Figure 9 The case of a complete collimating metasurface, i.e., the simultaneous presence of a dielectric filter and a collimating superlens, is given, in which the divergence angle is collimated to <±5°. Figure 10 The image shows the intensity distribution of a portion of the Micro-LED array after collimation via a metasurface. The LED pixel spots are closely arranged without large-area overlap, which can meet the requirements for high-resolution near-eye display in XR scenarios.

[0039] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A Micro-LED collimation system based on metasurfaces, characterized in that: Including Micro-LEDs and metasurfaces, The metasurface is composed of a dielectric filter and a collimating superlens. The collimating superlens is located downstream of the dielectric filter and consists of three layers: a substrate, a microstructure, and a protective layer.

2. The Micro-LED collimation system based on metasurfaces according to claim 1, characterized in that: A dielectric filter is an angle filter composed of multiple layers of dielectric film.

3. The Micro-LED collimation system based on metasurface according to claim 2, characterized in that: Angle filters have a specific filter angle θc, where θc < 50°.

4. The Micro-LED collimation system based on metasurface according to claim 3, characterized in that: θc is 10°, 20°, or 35°.

5. The Micro-LED collimation system based on metasurface according to claim 1, characterized in that, The substrate, microstructure, and protective layer are all made of materials transparent to the designed wavelength, and their refractive indices are related as follows: n 基底 ≤n 保护层 <n 微结构 .

6. A Micro-LED collimation system based on metasurfaces according to claim 1 or 5, characterized in that: The phase can be adjusted by changing the geometric dimensions of the microstructure, thus achieving control within the 0-2π range.

7. The Micro-LED collimation system based on metasurfaces according to claim 1, characterized in that: Micro-LEDs operate at visible or near-infrared wavelengths, ranging from 400nm to 1000nm.

8. The Micro-LED collimation system based on metasurface according to claim 7, characterized in that: The wavelengths are 405nm, 550nm, 632nm, 850nm or 940nm.

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