Optical anti-counterfeiting GaN metasurface and optical anti-counterfeiting product

Abstract

The invention belongs to the technical field of optical anti-counterfeiting, and relates to an optical anti-counterfeiting GaN metasurface and an optical anti-counterfeiting product. The optical anti-counterfeiting metasurface comprises a substrate layer and a light reflection structure, the light reflection structure is arranged on the surface of one side of the substrate layer and is used for reflecting incident light so as to output emergent light of which the wavelength continuously changes within a set angle range; the light reflection structure comprises a plurality of first reflection cylinders, the first reflection cylinders are arranged on the surface of one side of the substrate layer in an array mode, and a groove is formed between every two adjacent first reflection cylinders. By adopting the optical anti-counterfeiting GaN metasurface provided by the scheme, 10nm-level narrow-band wavelength selection can be performed on incident light, emergent light with extremely high saturation color can be observed in any direction in the plane where the metasurface is located based on human vision under the condition of sunlight irradiation, and the color of the emergent light continuously changes along with the observation angle, so that the color of the emergent light is changed continuously. Therefore, the optical anti-counterfeiting function is achieved, special optical materials are not needed, cost is low, and the structure is simple.

Description

Technical Field

[0001] The present invention relates to the field of optical anti-counterfeiting technology, and in particular to an optical anti-counterfeiting GaN supersurface and an optical anti-counterfeiting product. Background Art

[0002] With the continuous advancement of science and technology and the continuous development of social economy, anti-counterfeiting technology is also constantly innovating and improving. In recent years, optical anti-counterfeiting technology has been widely used in the fields of currency, commodities, identity documents, etc., and has gradually developed into an important means to ensure product authenticity and prevent counterfeiting in modern society. In the field of currency, by adopting high-resolution optical imaging technology, banknotes with tiny text and details can be produced, increasing the difficulty of currency counterfeiting; in the field of commodities, by adding logos and labels with specific optical effects to medicines, luxury goods and electronic products, consumers can judge the authenticity of commodities through simple optical detection methods; in the field of identity documents, by adopting optical imaging technology, optical information storage technology and optical color change technology, highly anti-counterfeiting identity cards, passports and driver's licenses can be produced.

[0003] Existing optical anti-counterfeiting technologies mainly include photovariable anti-counterfeiting, multi-spectral anti-counterfeiting and fluorescent anti-counterfeiting. Photovariable anti-counterfeiting uses optical principles and the optical properties of special materials to achieve anti-counterfeiting functions. For example, the molecular structure of photovariable materials changes under the irradiation of light of different wavelengths, resulting in changes in the characteristics of absorbing and reflecting light, producing a photovariable effect, so that the authenticity of the product can be verified based on this unique photovariable effect. However, since photovariable materials require special chemical components and complex preparation processes, the application of photovariable material anti-counterfeiting technology to products will increase the production cost of the product. Multi-spectral anti-counterfeiting refers to the fact that multi-spectral pigments or dyes show special colors under light of a specific wavelength band, so that the authenticity of the product can be verified based on this color characteristic. However, this optical anti-counterfeiting technology relies on specific lighting conditions, and the spectral characteristics of multi-spectral materials in specific wavelength bands are easily interfered by other substances. For example, stains or impurities on the surface of the product will absorb or scatter light of a specific wavelength band, thereby affecting the accuracy of the anti-counterfeiting effect. Fluorescent anti-counterfeiting uses the fluorescent property of materials to show special brightness or color under ultraviolet light or light of a specific wavelength to verify the authenticity of products. However, this optical anti-counterfeiting technology also requires specific lighting conditions and the use of professional equipment such as ultraviolet lamps. In addition, after long-term use or multiple exposures to light, the fluorescent brightness of fluorescent materials will gradually decay, resulting in a poor anti-counterfeiting effect.

[0004] In summary, existing optical anti-counterfeiting technologies have the problems of high cost, high requirements for lighting conditions, and poor anti-counterfeiting effect. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems of the optical anti-counterfeiting technology in the prior art, such as high cost, high requirements on lighting conditions and poor anti-counterfeiting effect.

[0006] In order to solve the above technical problems, the present invention provides an optical anti-counterfeiting GaN supersurface, comprising: Basal layer; A light reflection structure is arranged on a surface of one side of the substrate layer, and is used to reflect incident light, thereby outputting outgoing light with a wavelength that continuously changes within a set angle range; The light reflecting structure includes a plurality of first reflecting columns, which are arranged in an array on a surface of one side of the base layer, and a groove is provided between two adjacent first reflecting columns.

[0007] In the present application, a highly symmetric periodic structure is set in the entire area on the substrate layer to form a bound state in the quasi-continuous spectrum (Bound States in the Continuum, BIC) mode that can filter the incident light. When light beams of various wavelengths in sunlight (i.e., parallel white light) are incident on the light reflecting structure, they are diffracted under the periodic modulation of the first reflecting column. Since the diffraction angles of light beams of different wavelengths are different, the light beams of each diffraction order interfere with each other, and light beams of some wavelengths are bound in the light reflecting structure, while light beams of specific wavelengths are reflected by the light reflecting structure and emitted at a specific emission angle. At the same time, under the combined effect of the quasi-BIC mode and the dispersion of the light reflecting structure itself, the intensity of the emitted light of different wavelengths reflected by the light reflecting structure increases or decreases to varying degrees. Therefore, the emitted light with continuously changing wavelength can be observed within the set angle range, so that the emitted light with continuously changing color can be observed based on human vision, thereby realizing the optical anti-counterfeiting function.

[0008] Preferably, the light reflecting structure further comprises a second reflecting column, which is arranged between adjacent first reflecting columns, and the top of the second reflecting column is in contact with the bottom of the groove; Wherein, the height of the second reflective column is smaller than the height of the first reflective column.

[0009] In the present application, by setting a second reflective column with a height smaller than that of the first reflective column at the groove, the light reflection structure can still form a quasi-BIC mode, thereby selecting the wavelength of the incident light, so that the wavelength of the outgoing light changes continuously within the set angle range, thereby realizing the optical anti-counterfeiting function.

[0010] Preferably, it also includes: The matching layer is arranged on the surface of the light reflecting structure away from the base layer. A protrusion matching the groove is arranged on the side of the matching layer close to the light reflecting structure, and the top of the protrusion contacts the top of the groove.

[0011] In the present application, a matching layer is covered on the surface of the light reflecting layer to increase the upper and lower symmetry of the optical anti-counterfeiting metasurface, thereby expanding the bandwidth of the quasi-BIC mode to more than 100nm, that is, broadening the wavelength variation range of the outgoing light, so that the human eye can more clearly observe the color changes of the outgoing light at different output angles, thereby improving the anti-counterfeiting effect.

[0012] Preferably, the material of the base layer is aluminum oxide or silicon dioxide; and / or The material of the light reflection structure is gallium nitride.

[0013] In the present application, the substrate layer and the light reflecting structure may also be made of other materials. Preferably, aluminum oxide has strong corrosion resistance and chemical stability, can maintain the integrity of the structure under various environments, provide stable support for the light reflecting structure, and ensure the long-term reliability of the entire optical anti-counterfeiting metasurface. In addition, aluminum oxide also has good optical transparency, and relatively low absorption and scattering of light; gallium nitride has a high refractive index, and can achieve a strong light reflection effect during the light reflection process, enhance the optical linearity such as diffraction and interference of light in the light reflecting structure, thereby better realizing the quasi-BIC mode; in addition, aluminum oxide and gallium nitride have a high degree of adaptability in the lattice structure, so that the light reflecting structure can be better grown on the substrate layer, forming a high-quality interface, reducing lattice defects and stress, and improving the optical performance and stability of the optical anti-counterfeiting metasurface.

[0014] Preferably, the size ratio of the first reflective column to the groove is 4:1; and / or The diameter or side length of the first reflective column is 160nm-200nm; and / or The height of the first reflective column is 160nm-200nm.

[0015] In the present application, the change in the size of the light reflecting structure will directly affect the diffraction and interference of light therein, producing different quasi-BIC modes, so that the wavelength range that can be reflected by the light reflecting structure changes, achieving different wavelength screening effects, so that the emitted light produces different color changes within different set angle ranges.

[0016] Preferably, the setting angle range is 5°~25°; and / or The wavelength range is 430nm~540nm.

[0017] In the present application, by changing the size of the light reflecting structure, the color of the emitted light can change within the range of 5°~25°, and the wavelength change range of the emitted light within the set angle range can reach 430nm~540nm, so that the change of the emitted light from blue-purple to bright green can be observed.

[0018] Preferably, when the diameter or side length of the first reflective column is 160 nm, the height of the first reflective column is 160 nm, and the size of the groove is 40 nm, the set angle range is 5°~25°, and the wavelength variation range is 430 nm~530 nm.

[0019] In the present application, by limiting the size of the first reflective cylinders and the size of the grooves between adjacent first reflective cylinders, the change of the emitted light from blue-purple to bright green can be observed within the range of 5° to 25°.

[0020] Preferably, when the diameter or side length of the first reflective column is 200 nm, the height of the first reflective column is 200 nm, and the size of the groove is 50 nm, the set angle range is 5°~15°, and the wavelength variation range is 500 nm~540 nm.

[0021] In the present application, by limiting the size of the first reflective cylinders and the size of the grooves between adjacent first reflective cylinders, a change in the emitted light from blue-green to yellow-green can be observed within a range of 5° to 15°.

[0022] Preferably, the first reflective column is a circular column, a square column or a polygonal column; and / or The second reflective column is a circular column, a square column or a polygonal column.

[0023] The present invention also provides an optical anti-counterfeiting product, which includes the above-mentioned optical anti-counterfeiting GaN supersurface.

[0024] The optical anti-counterfeiting GaN supersurface provided by the present invention includes a substrate layer and a light reflecting structure arranged on one side surface of the substrate layer, the light reflecting structure is used to reflect incident light so that the wavelength of the emitted light changes continuously within a set emission angle range; the light reflecting structure includes a plurality of first reflecting columns, the plurality of first reflecting columns are arranged in an array on one side surface of the substrate layer, and a groove is provided between two adjacent first reflecting columns. A highly symmetric periodic structure is set over the entire area of ​​the substrate layer to form a bound states in the quasi-continuous spectrum (Bound States in the Continuum, BIC) mode that can filter the incident light. When light beams of various wavelengths in sunlight (i.e., parallel white light) are incident on the light reflecting structure, they are diffracted under the periodic modulation of the first reflecting column. Since the diffraction angles of light beams of different wavelengths are different, the light beams of each diffraction order interfere with each other, and light beams of some wavelengths are bound in the light reflecting structure, while light beams of specific wavelengths are reflected by the light reflecting structure and emitted at a specific emission angle. At the same time, under the combined effect of the quasi-BIC mode and the dispersion of the light reflecting structure itself, the intensity of the emitted light of different wavelengths reflected by the light reflecting structure increases or decreases to varying degrees. Therefore, the emitted light with a continuous and slowly changing wavelength can be observed within the set angle range, so that the emitted light with a slowly changing color can be observed based on human vision. The present application designs a light reflecting structure with quasi-BIC characteristics to select the wavelength of incident light and output outgoing light of a specific wavelength. At the same time, the outgoing light of different wavelengths is enhanced or weakened by combining the dispersion effect of the light reflecting structure. The optical anti-counterfeiting function can be achieved under sunlight conditions, and the outgoing light band observed by the human eye at any angle is less than or equal to 10nm, with extremely high saturation, without the need to use special optical materials, with low cost and simple structure, and can realize the light field control function in a quasi-two-dimensional plane at the sub-wavelength level. It has broad application prospects in the field of optical anti-counterfeiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 A schematic diagram of the first structure of the optical anti-counterfeiting GaN metasurface provided in this application; Figure 2 A schematic diagram of the second structure of the optical anti-counterfeiting GaN metasurface provided in this application; Figure 3 A third structural schematic diagram of the optical anti-counterfeiting GaN supersurface provided in this application; Figure 4 Schematic diagram of the three-dimensional structure of the optical anti-counterfeiting GaN supersurface provided in this application; Figure 5A schematic diagram of the unit structure of the optical anti-counterfeiting GaN supersurface provided in this application; Figure 6 Schematic diagram of the optical anti-counterfeiting GaN metasurface function provided for this application; Figure 7 The process flow chart of the preparation of the optical anti-counterfeiting GaN super surface provided in this application; wherein, Figure 7 (a) is a schematic diagram of the basal layer. Figure 7 (b) in Figure 7 Schematic diagram of preparing a reflective layer on the structure shown in (a). Figure 7 (c) in Figure 7 Schematic diagram of preparing a photoresist layer on the structure shown in (b). Figure 7 (d) in Figure 7 Schematic diagram of preparing the first reflective column on the structure shown in (c). Figure 7 The (e) in Figure 7 Schematic diagram of preparing a matching layer on the structure shown in (d); Figure 8 A schematic diagram of the color change of the output light of the optical anti-counterfeiting GaN metasurface provided in Example 1; Fig. 9 A schematic diagram of the transmittance of the optical anti-counterfeiting GaN metasurface provided in Example 1; Fig.10 The energy band diagram of the optical anti-counterfeiting GaN supersurface provided in Example 1; wherein, Fig.10 (a) is a schematic diagram showing the variation of the wavelength of the outgoing light with the wave vector. Fig.10 (b) is a schematic diagram of the change of quality factor with wave vector; Fig.11 A schematic diagram of the transmittance of the optical anti-counterfeiting GaN metasurface provided in Example 2; Fig.12 This is a schematic diagram of the energy bands of the optical anti-counterfeiting GaN supersurface provided in Example 2; wherein, Fig.12 (a) is a schematic diagram showing the variation of the wavelength of the outgoing light with the wave vector. Fig.12 (b) is a schematic diagram of the change of quality factor with wave vector; Explanation of the reference numerals in the specification: 1. base layer; 2. light reflecting structure; 21. first reflecting column; 22. groove; 23. second reflecting column; 3. matching layer; 31. protrusion; 200. reflecting layer; 300. photoresist layer. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0027] The Bound States in the Continuum (BIC) mode is a special optical phenomenon. In traditional optical systems, light usually propagates or scatters in the medium, and the BIC mode refers to the existence of special eigenstates in the optical system. Although these eigenstates are in a continuous scattering state spectrum, they can be completely bound inside the optical system without radiation loss. This is because factors such as optical structure and boundary conditions cause light to form a stable standing wave mode under specific conditions, thereby being confined to a specific area.

[0028] The BIC mode is divided into the perfect BIC mode and the quasi-BIC mode. The perfect BIC mode means that the incident light is completely confined inside the optical structure. At this time, the interaction between light and matter reaches its extreme, and the light field can be stored and enhanced for a long time in the optical structure, thereby producing a greater optical nonlinear effect and a higher light absorption rate; while the quasi-BIC mode is not as good as the perfect BIC mode in terms of light confinement effect, and can only confine part of the incident light. Its light field localization and the intensity of light-matter interaction are both weak. Since the quasi-BIC mode's light confinement and storage effects cannot meet the requirements of application scenarios that require strong optical effects, the application and research of the BIC mode in the prior art are mostly concentrated on the perfect BIC mode.

[0029] The present application extends the partial binding effect of the quasi-BIC mode on light to its filtering and screening function for light, and applies this characteristic of the quasi-BIC mode to the field of optical anti-counterfeiting for the first time. By designing a light reflection structure that can produce the quasi-BIC mode, the incident light is filtered and screened, thereby outputting reflected light of a specific wavelength. At the same time, under the dispersion effect of the light reflection structure itself, the intensity of reflected light of different wavelengths will be enhanced or weakened to different degrees, thereby emitting outgoing light with a continuous and slowly changing wavelength within a specific angle range, thereby achieving optical anti-counterfeiting.

[0030] See also Figure 1 , Figure 1 This is a schematic diagram of the first structure of the optical anti-counterfeiting GaN supersurface provided in the present application, wherein the optical anti-counterfeiting GaN supersurface includes a substrate layer 1 and a light reflecting structure 2.

[0031] The light reflecting structure 2 is disposed on one side of the substrate layer 1, and is used to reflect the incident light, thereby outputting an outgoing light with a wavelength that continuously changes within a set angle range. Specifically, the set angle range is 5° to 25°, and the wavelength change range is 430nm to 540nm.

[0032] It is worth noting that based on human vision, the outgoing light with continuously changing color can be observed at any angle of this metasurface, and the outgoing light band observed at any angle is less than or equal to 10nm, with extremely high saturation.

[0033] The light reflective structure 2 includes a plurality of first reflective columns 21 , which are arranged in an array on one side of the substrate layer 1 , and a groove 22 is provided between two adjacent first reflective columns 21 .

[0034] Specifically, the optical anti-counterfeiting metasurface provided in the present application forms a symmetrically protected quasi-BIC mode, and uses the symmetrically protected quasi-BIC mode to screen the incident light. The specific principle is: when the normal (z-axis) around the photonic crystal plate is When the structure is rotated by an angle, the parallel wave vector of a type of electromagnetic mode always remains unchanged. In order to ensure this feature, the parallel wave vector of this type of electromagnetic mode is usually located in the wave vector space. point (vertical incidence), at this time, the wave vectors of these modes have no horizontal component, that is, .exist point, the even-symmetric electromagnetic mode is completely decoupled from the odd-symmetric electromagnetic mode. Since the structure has C2 symmetry, the even-symmetric electromagnetic mode will be completely confined in the structure, while the odd-symmetric electromagnetic mode will radiate out of the structure. When the radiation frequency is lower than the diffraction limit (diffraction limit definition ,in, is the speed of light in vacuum, represents the refractive index of the ambient medium, represents the periodic constant), the radiation direction is only in the normal direction of the plate, leaving After the point, at least one of the horizontal wave vector components kx and ky of the electromagnetic mode is no longer zero. The rotation operation no longer ensures the invariance of the horizontal wave vector. Therefore, by oblique incidence, the wave vector space deviates The point destroys the wave vector symmetry. Due to the loss of symmetry protection, the BIC will couple with the radiation mode to form a leaky quasi-BIC, causing energy to leak out.

[0035] Optionally, the first reflective column 21 may be a circular column, a square column or other polygonal column. The material of the base layer 1 may be one of aluminum oxide (Al2O3) and silicon dioxide (SiO2); the material of the light reflective structure 2 is gallium nitride (GaN).

[0036] Preferably, in one embodiment of the present application, the material of the base layer 1 is aluminum oxide, and the material of the light reflecting structure 2 is gallium nitride. This is because aluminum oxide has good chemical stability and optical transparency, which can not only provide stable support for the light reflecting structure 2, but also will not affect the propagation and reflection of light in the light reflecting structure 2, which is beneficial to ensure the intensity and quality of the optical signal; the gallium nitride material has a high refractive index and can achieve a strong light reflection effect during the light reflection process, which is beneficial to the modulation and manipulation of light; at the same time, aluminum oxide and gallium nitride materials have a high degree of adaptability in the lattice structure, which also enables the light reflecting structure 2 to grow more stably on the surface of the base layer 1, thereby improving the optical performance and stability of the optical anti-counterfeiting metasurface.

[0037] like Figure 2 As shown, in some embodiments of the present application, the light reflective structure 2 further includes a second reflective column 23, which is disposed between adjacent first reflective columns 21, and the top of the second reflective column 23 is in contact with the bottom of the groove 22. The height of the second reflective column 23 is less than the height of the first reflective column 21.

[0038] Optionally, the second reflective column 23 may be a circular column, a square column or other polygonal columns.

[0039] like Figure 3 and Figure 4 As shown, in some embodiments of the present application, the optical anti-counterfeiting GaN supersurface also includes a matching layer 3.

[0040] The matching layer 3 is disposed on the surface of the light reflecting structure 2 away from the base layer 1 . A protrusion 31 matching the groove 22 is disposed on the side of the matching layer 3 close to the light reflecting structure 2 . The top of the protrusion 31 contacts the top of the groove 22 .

[0041] By embedding the light reflection structure 2 into the matching layer 3, the upper and lower symmetry of the optical anti-counterfeiting metasurface can be increased, thereby broadening the bandwidth of the quasi-BIC mode and extending the wavelength variation range of the outgoing light to 100 nm, making it easier for the human eye to distinguish the color changes of the outgoing light and improving the anti-counterfeiting effect.

[0042] Optionally, the material of the matching layer may be SiO2, Al2O3, or an organic material, such as photoresist, PMMA, or protective glue.

[0043] like Figure 5 As shown, a reflection unit composed of a single first reflection column 21 and a substrate layer 1 in the optical anti-counterfeiting GaN supersurface, in which p represents the size of the reflection unit, r represents the radius of the first reflection column 21, and h represents the height of the first reflection column 21.

[0044] By changing the size of the light reflecting structure 2, the diffraction and interference of light therein can be changed, thereby generating different quasi-BIC modes, so that the wavelength range that can be reflected by the light reflecting structure 2 is changed, achieving different wavelength screening effects, so that the emitted light produces different color changes within different set angle ranges.

[0045] Furthermore, the size of the reflection unit is 200 nm to 250 nm. For example, the size of the reflection unit may be 200 nm, 220 nm, or 240 nm.

[0046] Furthermore, the size ratio of the first reflective column 21 to the groove 22 is 4:1.

[0047] Further, the diameter or side length of the first reflective column 21 is 160 nm to 200 nm. For example, the diameter or side length of the first reflective column 21 may be 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm.

[0048] Further, the height of the first reflective column 21 is 160 nm-200 nm. For example, the height of the first reflective column 21 may be 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm.

[0049] This embodiment does not limit the shape of the groove 22. For example, the shape of the groove 22 can be a cylinder or a cubic column. When the shape of the groove 22 is a cylinder, the size of the groove 22 is the diameter of the cylinder; when the shape of the groove 22 is a cubic column, the size of the groove 22 is the side length of the cross section of the cubic column.

[0050] In one embodiment, when the diameter or side length of the first reflective column 21 is 160 nm, the height of the first reflective column 21 is 160 nm, and the size of the groove 22 is 40 nm, the angle range is set to 5°~25°, and the wavelength variation range is 430nm~530nm.

[0051] In another embodiment, when the diameter or side length of the first reflective column 21 is 200 nm, the height of the first reflective column 21 is 200 nm, and the size of the groove 22 is 50 nm, the angle range is set to 5°~15°, and the wavelength variation range is 500nm~540nm.

[0052] like Figure 6Shown is a schematic diagram of the function of the optical anti-counterfeiting GaN metasurface. The light emitted by the sun contains various angles and wavelengths. When the sunlight is incident on the optical anti-counterfeiting metasurface, the angle at which the human eye is located represents the angle of incidence of the sunlight seen by the human eye. The optical anti-counterfeiting metasurface reflects light of different wavelengths at different incident angles. As the observation angle of the human eye in any direction of the metasurface gradually expands from 0°, it can be clearly seen that the color of the emitted light changes continuously from blue to green.

[0053] Based on the optical anti-counterfeiting GaN supersurface provided in the above-mentioned embodiment, the embodiment of the present application also provides an optical anti-counterfeiting product, which includes the above-mentioned optical anti-counterfeiting GaN supersurface.

[0054] like Figure 7 The figure shows a process flow chart of preparing the optical anti-counterfeiting GaN supersurface provided in this embodiment. The method of preparing the optical anti-counterfeiting GaN supersurface includes: S10: Provide a base layer 1, such as Figure 7 As shown in (a) in .

[0055] S20: forming a reflective layer 200 on one side of the substrate layer 1, such as Figure 7 As shown in (b) in .

[0056] S30: Spin-coating a photoresist layer 300 on the side of the reflective layer 200 away from the base layer 1, and exposing the photoresist layer 300 using a double-beam holographic exposure method to form a two-dimensional columnar structure, such as Figure 7 As shown in (c) in .

[0057] S40: etching the photoresist layer 300 and the reflective layer 200 to form a light reflective structure including a plurality of first reflective columns 21, such as Figure 7 As shown in (d) in .

[0058] S50: Depositing a matching layer 3 between adjacent first reflective columns 21 and on top of the first reflective columns 21, such as Figure 7 As shown in (e) in .

[0059] The technical solution of the present application is described in more detail below in combination with a plurality of embodiments and comparative examples, but it should be understood that the following embodiments and comparative examples are only for explaining and illustrating the technical solution and do not limit the scope of the present application. Example 1

[0060] The present embodiment provides an optical anti-counterfeiting GaN supersurface, which includes a base layer, a light reflecting structure and a photoresist layer, wherein the light reflecting structure includes a plurality of first reflecting columns arranged in an array on a surface of one side of the base layer, and a groove is provided between two adjacent first reflecting columns.

[0061] The material of the base layer is Al2O3, and the material of the light reflection structure is GaN.

[0062] The first reflective column is a cylinder.

[0063] The size of the reflection unit is 200 nm, the size ratio of the first reflection column to the groove is 4:1, the diameter of the first reflection column is 160 nm, and the height of the first reflection column is 160 nm.

[0064] like Figure 8 Shown is a schematic diagram of the color change of the output light of the optical anti-counterfeiting GaN supersurface provided in this embodiment. It can be seen from the figure that this embodiment limits the size of the light reflection structure so that after the sunlight is incident on the optical anti-counterfeiting GaN supersurface, the output light can be observed to change from blue to green within the range of 5°~25°.

[0065] like Fig. 9 The figure shows the transmittance diagram of the optical anti-counterfeiting GaN supersurface provided in this embodiment. It can be clearly observed from the figure that when the incident light is incident vertically at 0°, the optical anti-counterfeiting GaN supersurface maintains low reflectivity for a light beam with a wavelength of 410nm. As the incident angle gradually increases, a high reflectivity slit appears and moves to a high wavelength with dispersion. It can be seen from the figure that as the incident angle changes from 5° to 25°, the wavelength of the outgoing light gradually changes from 430nm to 530nm. Based on human vision, the continuous change of the outgoing light from blue to green can be seen, indicating that the optical anti-counterfeiting GaN supersurface provided in this embodiment can use BIC and dispersion characteristics to achieve wavelength screening function.

[0066] like Fig.10 FIG. 1 is a schematic diagram of the energy band of the optical anti-counterfeiting GaN supersurface provided in this embodiment; wherein, Fig.10 (a) is a schematic diagram showing the variation of the wavelength of the outgoing light with the wave vector. Fig.10 (b) in the figure is a schematic diagram showing the change of quality factor with wave vector. Fig.10 As can be seen from (a) in the figure, at a wavelength of about 410nm (the curve corresponding to solution = 2 in the figure), the optical anti-counterfeiting GaN supersurface has a quasi-BIC mode, and Fig.10 As can be seen from (b) in the figure, the quality factor of the quasi-BIC mode reaches , which is much higher than the other curves, indicating that the optical anti-counterfeiting GaN metasurface provided in this embodiment can select and filter light of a specific wavelength with high precision. Example 2

[0067] The present embodiment provides an optical anti-counterfeiting GaN supersurface, which includes a base layer, a light reflecting structure and a photoresist layer, wherein the light reflecting structure includes a plurality of first reflecting columns arranged in an array on a surface of one side of the base layer, and a groove is provided between two adjacent first reflecting columns.

[0068] The material of the base layer is Al2O3, and the material of the light reflection structure is GaN.

[0069] The first reflective column is a cylinder.

[0070] The size of the reflection unit is 250 nm, the size ratio of the first reflection column to the groove is 4:1, the diameter of the first reflection column is 200 nm, and the height of the first reflection column is 200 nm.

[0071] like Fig.11 The figure shows the transmittance diagram of the optical anti-counterfeiting GaN supersurface provided in this embodiment. It can be clearly observed from the figure that when the incident light is incident vertically at 0°, the optical anti-counterfeiting GaN supersurface maintains low reflectivity for a light beam with a wavelength of 490nm. As the incident angle gradually increases, a high reflectivity slit appears and moves to a high wavelength with dispersion. It can be seen from the figure that as the incident angle changes from 5° to 15°, the wavelength of the outgoing light gradually changes from 500nm to 530nm. Based on human vision, the continuous change of the outgoing light from blue-green to yellow-green can be seen, indicating that the optical anti-counterfeiting GaN supersurface provided in this embodiment can use BIC and dispersion characteristics to achieve wavelength screening function.

[0072] like Fig.12 FIG. 1 is a schematic diagram of the energy band of the optical anti-counterfeiting GaN supersurface provided in this embodiment; wherein, Fig.12 (a) is a schematic diagram showing the variation of the wavelength of the outgoing light with the wave vector. Fig.12 (b) in the figure is a schematic diagram showing the change of quality factor with wave vector. Fig.12 As can be seen from (a) in the figure, at a wavelength of about 500nm (the curve corresponding to solution = 1 in the figure), the optical anti-counterfeiting GaN supersurface has a quasi-BIC mode, and Fig.12 As can be seen from (b) in the figure, the quality factor of the quasi-BIC mode reaches , which is much higher than the other curves, indicating that the optical anti-counterfeiting GaN metasurface provided in this embodiment can select and filter light of a specific wavelength with high precision. Example 3

[0073] The present embodiment provides an optical anti-counterfeiting GaN supersurface, which includes a base layer and a light reflecting structure, wherein the light reflecting structure includes a plurality of first reflecting columns arranged in an array on a surface of one side of the base layer, and a groove is provided between two adjacent first reflecting columns.

[0074] The material of the base layer is Al2O3, and the material of the light reflection structure is GaN.

[0075] The first reflective column is a cylinder.

[0076] The size of the reflection unit is 250 nm, the size ratio of the first reflection column to the groove is 4:1, the diameter of the first reflection column is 200 nm, and the height of the first reflection column is 200 nm.

[0077] The optical anti-counterfeiting super-GaN surface provided in this embodiment can also select and filter light of a specific wavelength, but the color of its output light can only change from blue to light blue, which is difficult for the human eye to distinguish. By comparing Example 2 and Example 3, it can be seen that by covering the light reflection structure with a photoresist layer, the upper and lower symmetry of the optical anti-counterfeiting GaN super-surface can be increased, thereby effectively expanding the bandwidth of the quasi-BIC mode, making the color change of the output light more obvious, thereby improving the anti-counterfeiting effect.

[0078] The optical anti-counterfeiting GaN metasurface provided by the present application selects the wavelength of the incident light and outputs the outgoing light of a specific wavelength by designing a light reflection structure with quasi-BIC characteristics, and at the same time enhances or weakens the outgoing light of different wavelengths by combining the dispersion effect of the light reflection structure, so that the anti-counterfeiting function can be realized under sunlight, without the need for specific lighting conditions and special optical materials, and without the need to customize specific patterns. The structure is simple, and the weight and volume of the structure are greatly reduced by realizing the light field control function in a quasi-two-dimensional plane at the sub-wavelength level. It has the advantages of extremely high customization, flexibility, ultra-thinness, lightness, high integration and efficient optical performance. At the same time, since the present application adopts a two-dimensional cylinder to design the light reflection structure, the human eye can observe the outgoing light whose color changes slowly with the outgoing angle in any direction. In addition, since the quality factor value of the quasi-BIC mode of the light reflection structure designed in the present application is relatively high, the color saturation of the outgoing light is relatively high, which is easier to observe with the naked eye, and has broad application prospects in the field of optical anti-counterfeiting.

[0079] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. An optical anti-counterfeiting GaN supersurface, characterized in that: include: Basal layer; A light reflection structure is arranged on a surface of one side of the substrate layer, and is used to reflect incident light, thereby outputting outgoing light with a wavelength that continuously changes within a set angle range; The light reflecting structure includes a plurality of first reflecting columns, which are arranged in an array on a surface of one side of the base layer, and a groove is provided between two adjacent first reflecting columns.

2. The optical anti-counterfeiting GaN supersurface according to claim 1, characterized in that: The light reflecting structure further includes a second reflecting column, which is arranged between adjacent first reflecting columns, and the top of the second reflecting column is in contact with the bottom of the groove; Wherein, the height of the second reflective column is smaller than the height of the first reflective column.

3. The optical anti-counterfeiting GaN supersurface according to claim 1 or 2, characterized in that: Also includes: The matching layer is arranged on the surface of the light reflecting structure away from the base layer. A protrusion matching the groove is arranged on the side of the matching layer close to the light reflecting structure, and the top of the protrusion contacts the top of the groove.

4. The optical anti-counterfeiting GaN supersurface according to claim 1, characterized in that: The material of the base layer is aluminum oxide or silicon dioxide; and / or The material of the light reflection structure is gallium nitride.

5. The optical anti-counterfeiting GaN supersurface according to claim 1, characterized in that: The size ratio of the first reflective column to the groove is 4:1; and / or The diameter or side length of the first reflective column is 160nm-200nm; and / or The height of the first reflective column is 160nm-200nm.

6. The optical anti-counterfeiting GaN supersurface according to claim 1, characterized in that: The setting angle range is 5°~25°; and / or The wavelength range is 430nm~540nm.

7. The optical anti-counterfeiting GaN supersurface according to claim 1, characterized in that: When the diameter or side length of the first reflective column is 160 nm, the height of the first reflective column is 160 nm, and the size of the groove is 40 nm, the set angle range is 5°~25°, and the wavelength variation range is 430 nm~530 nm.

8. The optical anti-counterfeiting GaN supersurface according to claim 1, characterized in that: When the diameter or side length of the first reflective column is 200 nm, the height of the first reflective column is 200 nm, and the size of the groove is 50 nm, the set angle range is 5°~15°, and the wavelength variation range is 500 nm~540 nm.

9. The optical anti-counterfeiting GaN supersurface according to claim 2, characterized in that: The first reflective column is a circular column, a square column or a regular polygonal column; and / or The second reflective column is a circular column, a square column or a regular polygonal column.

10. An optical anti-counterfeiting product, characterized in that: The optical anti-counterfeiting product comprises the optical anti-counterfeiting GaN supersurface described in any one of claims 1 to 9.

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