A medium metasurface structural color device and a structural color brightness regulation method

Abstract

The application discloses a kind of medium metasurface structural color devices, comprising: transparent medium substrate;And medium nanometer rectangular column hexagonal periodic array is arranged on the surface of the substrate, the value range of lattice constant is;Wherein, the medium nanometer rectangular column is height, length and width satisfy the relationship formula:, and length-width ratio remains, length and width are jointly optimized according to narrow-band reflection peak central wavelength.The structural color brightness control method is also disclosed.The application solves the problems that the existing structural color and metasurface device are generally reflected in the process of realizing visible light reflection type structural color, the color purity is limited due to the wide reflection spectrum line, the parameter design of different color pixels lacks the resonant positioning rule of calculation, and the brightness continuous modulation ability is insufficient under the condition of keeping hue stable.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano photonics and optical device technology, specifically a dielectric metasurface structured color device and a method for controlling the brightness of structured color. Background Technology

[0002] Structural color refers to the color produced by the scattering, interference, or resonance modulation of light through micro- and nano-structures. Compared with traditional pigments and dyes, structural colors have advantages such as being less prone to fading, being able to achieve high-resolution pixelation, and being easy to integrate with micro- and nano-manufacturing processes. They are widely used in display, optical anti-counterfeiting, information encoding, and sensing fields.

[0003] Existing structural color schemes mainly include multilayer thin-film interference structures, plasmonic resonance structures of metal nanostructures, and Mie resonance structures of dielectric nanostructures (Mie resonance structures refer to low-loss dielectric materials such as TiO2 and Si). Multilayer thin-film interference structures typically rely on the number of stacked layers and thickness control to achieve color adjustment, resulting in large device thickness and limited pixel integration. Although metal plasmonic structures can provide significant resonance enhancement, they generally suffer from high ohmic loss, limited reflection efficiency, and thermal stability issues in the visible light band. Dielectric Mie structures, based on low-loss, high-refractive-index materials, can achieve high optical efficiency and good environmental stability, but there is still room for further optimization in improving color purity, achieving narrowband high-peak reflection, and realizing continuously controllable brightness (grayscale) modulation at the pixel scale.

[0004] Furthermore, periodic nanostructure arrays can exhibit Rayleigh anomalies induced by diffraction criticality under specific conditions, generating lattice resonances through collective array coupling. Lattice resonances offer narrower spectral characteristics than single-unit resonances, which is beneficial for improving the spectral purity of structural colors. However, the intensity and spectral morphology of lattice resonances are usually closely related to the unit cell scattering response. Without a design that matches the Rayleigh anomaly to the unit cell resonance wavelength, problems such as insufficient resonance intensity, limited effective color range, or insufficient brightness control may easily occur. Simultaneously, practical applications also require consideration of device manufacturability, pixelation integration capabilities, and stable output under specific incident conditions.

[0005] Therefore, there is an urgent need to provide a dielectric metasurface structured color device and a method for controlling the brightness of the structured color. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a dielectric metasurface structured color device and a structured color brightness control method. It solves the problems commonly found in existing structured colors and metasurface devices during the visible light reflective structured color realization process, such as limited color purity due to wide reflection spectral lines, lack of calculable resonance positioning rules for the parameter design of different color pixels, and insufficient ability to achieve continuous brightness (grayscale) modulation while maintaining hue stability.

[0007] The technical solution to achieve the above objectives is:

[0008] One embodiment of the present invention provides a dielectric metasurface structured color device, comprising:

[0009] Transparent dielectric substrate;

[0010] And a hexagonal periodic array of dielectric nanorectangular pillars disposed on the surface of the substrate, with a lattice constant The range of values ​​is ;

[0011] in,

[0012] The dielectric nanorectangular pillars have a height ,length With width Satisfying the relation: , And the aspect ratio is maintained. ,length With width Joint optimization based on the center wavelength of the narrowband reflection peak;

[0013] at the angle of incidence Under near-normal incident conditions, the first-order Rayleigh anomaly wavelength on the substrate side satisfy:

[0014] ;

[0015] In the formula, For the substrate at wavelength The refractive index at that point;

[0016] By synergistically controlling the lattice constant With respect to the geometric parameters of the medium nanorectangular pillar This couples the multipolar scattering resonance of the nanopillars with the Rayleigh anomaly-induced surface lattice resonance, forming a full width at half maximum (FWHM). The narrowband reflection main peak is achieved. Wide color gamut structural color output within the working wavelength range.

[0017] Preferably, the substrate is silicon dioxide, the dielectric nanorectangular pillars are titanium dioxide, and the height of the dielectric nanorectangular pillars is... .

[0018] Preferably, the substrate is at a wavelength refractive index at The Cauchy dispersion model is satisfied in the visible light band:

[0019] .

[0020] Preferably, the device further includes a polarization multiplexing function:

[0021] When the incident ray polarization angle When the angle changes from 0° to 90°, the intensity of the main reflection peak is as follows: Regular decay.

[0022] A second method for controlling the brightness of structural colors according to the present invention, employing the aforementioned dielectric metasurface structural color device, includes:

[0023] Step S1: Set the height of the dielectric nanorectangular pillar. And select the lattice constant according to the target color. With respect to the geometric parameters of the medium nanorectangular pillar ;

[0024] Step S2: Calculate the first-order Rayleigh anomaly wavelength on the substrate side. ;

[0025] Step S3: Define the long axis direction of the medium nanorectangular pillar as the 0° reference axis;

[0026] Step S4: Control the polarization angle of the incident light by rotating the platform or using a liquid crystal phase modulator. The angle changes continuously from 0° to 90°.

[0027] Step S5 causes the device to generate a narrowband reflection peak in the visible light band reflection spectrum and output structural color, thereby achieving continuous modulation of the intensity of the main reflection peak and thus realizing structural color brightness control.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention introduces a lattice resonance induced by Rayleigh anomaly on the substrate side by constructing a hexagonal periodic array of titanium dioxide nanorectangular pillars on the surface of a silicon dioxide substrate, and hybridizes it with the Mie resonance of the unit nanopillars, thereby obtaining a narrow-band reflection peak under near-normal incident conditions; at the same time, the anisotropy of the nanorectangular pillars is used to achieve polarization-tunable reflection intensity modulation; the structured color device has high vividness and color purity as well as continuous brightness modulation, and can cover most of the visible light area to meet the application requirements of pixelated display, information encoding and anti-counterfeiting. Attached Figure Description

[0029] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0030] Figure 1 This is a schematic diagram of a dielectric metasurface structure color device according to the present invention;

[0031] Figure 2 This is a top view of a dielectric metasurface structure color device according to the present invention;

[0032] Figure 3 This is a flowchart of a structural color brightness control method according to the present invention;

[0033] Figure 4 This is a schematic diagram showing the relationship between the reflection peak and the Rayleigh anomaly induced by the base side in this invention;

[0034] Figure 5 This is the spectral diagram of blue in the RGB three primary colors of the metasurface reflection of the medium in the embodiment of the present invention;

[0035] Figure 6 This is the spectral diagram of green in the RGB three primary colors of the metasurface reflection of the medium in the embodiment of the present invention;

[0036] Figure 7 This is the spectrum of red in the RGB three primary colors of the metasurface reflection of the medium in this embodiment of the invention;

[0037] Figure 8 This is a reflection spectrum in an embodiment of the present invention, showing how the intensity of the reflection peak decreases with the change of the polarization angle. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] like Figure 1 As shown, a dielectric metasurface structured color device includes: a transparent dielectric substrate; and a hexagonal periodic array of dielectric nanorectangular pillars disposed on the surface of the substrate, with a lattice constant of... The range of values ​​is ;

[0040] in,

[0041] The dielectric nanorectangular pillars have a height ,length With width Satisfying the relation: , And the aspect ratio is maintained. ,length With width Joint optimization based on the center wavelength of the narrowband reflection peak;

[0042] at the angle of incidence Under near-normal incident conditions, the first-order Rayleigh anomaly wavelength on the substrate side satisfy:

[0043] ;

[0044] In the formula, For the substrate at wavelength The refractive index at such location, such as Figure 4 The diagram shown illustrates the relationship between the reflection peak and the Rayleigh anomaly induced by the basal side.

[0045] By synergistically controlling the lattice constant With respect to the geometric parameters of the medium nanorectangular pillar This couples the multipolar scattering resonance of the nanopillars with the Rayleigh anomaly-induced surface lattice resonance, forming a full width at half maximum (FWHM). The narrowband reflection main peak is achieved. Wide color gamut structural color output within the working wavelength range.

[0046] In this embodiment, the substrate is silicon dioxide, the dielectric nanorectangular pillars are titanium dioxide, and the height of the dielectric nanorectangular pillars is... .

[0047] In the embodiment, the substrate is at wavelength refractive index at The Cauchy dispersion model is satisfied in the visible light band:

[0048] .

[0049] In this embodiment, the device also includes a polarization multiplexing function:

[0050] When the incident ray polarization angle When the angle changes from 0° to 90°, the intensity of the main reflection peak is as follows: Regular decay.

[0051] In the embodiment, when the incident wavelength is close to the first-order Rayleigh anomaly wavelength... At this time, long-range coherent coupling is generated between the array scatterers through the lattice diffraction channel, forming a surface lattice resonance associated with Rayleigh anomaly; this collective resonance has stronger spectral selectivity than the single resonance, which can significantly narrow the reflection response spectral line and provide a narrow-band spectral basis for structural color; on the other hand, the dielectric nanorectangular pillars can support electric dipole, magnetic dipole and higher-order multipole scattering components, and the position and phase dispersion of their scattering spectrum are mainly determined by the geometric size.

[0052] This invention achieves this by jointly selecting the lattice constant. With nano rectangular column geometry This allows the nanopillars to provide sufficient scattering amplitude within the Rayleigh anomaly band, thereby effectively driving and enhancing the collective coupling in the lattice diffraction channel, forming a narrowband reflection peak determined by both lattice resonance and unit multipole scattering.

[0053] Because the equivalent polarizability of the nanorectangular pillars differs along their long and short axes, changing the angle between the incident beam polarization direction and the long axis of the nanorectangular pillars will continuously alter the excitation efficiency of the unit multipolar response and its coupling efficiency to the lattice diffraction channel. This allows for continuous adjustment of the intensity of the reflected main peak without changing or only slightly changing the center wavelength of the main peak, thereby enabling structural color brightness (grayscale) control and supporting polarization multiplexing display and information encoding.

[0054] like Figure 1-3 As shown, a structural color brightness control method, employing the aforementioned dielectric metasurface structural color device, includes:

[0055] Step S1: Set the height of the dielectric nanorectangular pillars And select the lattice constant according to the target color. With respect to the geometric parameters of the medium nanorectangular pillar ;

[0056] Step S2: Calculate the first-order Rayleigh anomaly wavelength on the substrate side. ;

[0057] Step S3: Define the long axis direction of the medium nanorectangular pillar as the 0° reference axis;

[0058] Step S4: Control the polarization angle of the incident light by rotating the platform or using a liquid crystal phase modulator. The angle changes continuously from 0° to 90°.

[0059] Step S5 causes the device to generate a narrowband reflection peak in the visible light band reflection spectrum and output structural color, thereby achieving continuous modulation of the intensity of the main reflection peak and thus realizing structural color brightness control.

[0060] The reflection efficiency and full width at half maximum (FWHM) of the three primary colors (red, green, and blue) were obtained through simulation calculations using COMSOL (multiphysics coupling simulation software) and FDTD (time-domain electromagnetic field simulation algorithm / software). The results are as follows:

[0061] Example 1: Blue, with a reflectivity of 100% and a full width at half maximum (FWHM) of 9.94 nm. Figure 5 As shown;

[0062] Example 2: Green, with a reflectivity of 98% and a full width at half maximum (FWHM) of 10.75 nm. Figure 6 As shown;

[0063] Example 3: Red, with a reflectivity of 100% and a full width at half maximum (FWHM) of 11.67 nm. Figure 7 As shown;

[0064] Meanwhile, simulations were conducted to verify the ability to continuously modulate the narrowband reflection peak intensity and thus control the structural color brightness (grayscale) in the blue polarization brightness modulation of Example 1. Figure 8 As shown in Example 1, the calculation of continuously adjustable brightness (in the figure: the horizontal axis represents the wavelength of the incident light, and the vertical axis represents the reflectivity) shows that as the polarization angle changes continuously, the original spectral profile remains unchanged, but the light intensity decreases continuously to a certain extent. It can be seen that the color brightness and saturation of this structural color device are at a high level, and it also possesses the ability to adjust intensity that other structural color devices do not have, providing a superior solution for the optical display industry and decorative fields.

[0065] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dielectric metasurface structured color device, characterized in that, include: Transparent dielectric substrate; And a hexagonal periodic array of dielectric nanorectangular pillars disposed on the surface of the substrate, with a lattice constant The range of values ​​is ; in, The dielectric nanorectangular pillars have a height ,length With width Satisfying the relation: , And the aspect ratio is maintained. ,length With width Joint optimization based on the center wavelength of the narrowband reflection peak; at the angle of incidence Under near-normal incident conditions, the first-order Rayleigh anomaly wavelength on the substrate side satisfy: ； In the formula, For the substrate at wavelength The refractive index at that point; By synergistically controlling the lattice constant With respect to the geometric parameters of the medium nanorectangular pillar This couples the multipolar scattering resonance of the nanopillars with the Rayleigh anomaly-induced surface lattice resonance, forming a full width at half maximum (FWHM). The narrowband reflection main peak is achieved. Wide color gamut structural color output within the operating wavelength band; The substrate at wavelength refractive index at The Cauchy dispersion model is satisfied in the visible light band: ； The device also includes a polarization multiplexing function: When the incident ray polarization angle When the angle changes from 0° to 90°, the intensity of the main reflection peak is as follows: Regular decay.

2. The dielectric metasurface structured color device according to claim 1, characterized in that, The substrate is silicon dioxide, the dielectric nanorectangular pillars are titanium dioxide, and the height of the dielectric nanorectangular pillars is... .

3. A method for controlling the brightness of structural colors, using the dielectric metasurface structural color device as described in any one of claims 1-2, characterized in that, include: Step S1: Set the height of the dielectric nanorectangular pillar. And select the lattice constant according to the target color. With respect to the geometric parameters of the medium nanorectangular pillar ; Step S2: Calculate the first-order Rayleigh anomaly wavelength on the substrate side. ; Step S3: Define the long axis direction of the medium nanorectangular pillar as the 0° reference axis; Step S4: Control the polarization angle of the incident light by rotating the platform or using a liquid crystal phase modulator. The angle changes continuously from 0° to 90°. Step S5 causes the device to generate a narrowband reflection peak in the visible light band reflection spectrum and output structural color, thereby achieving continuous modulation of the intensity of the main reflection peak and thus realizing structural color brightness control.

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