Dual-mode perfect absorber of quasi-continuous domain bound state all-dielectric metasurface and application of dual-mode perfect absorber

Abstract

The quasi-continuous domain bound state all-dielectric metasurface dual-mode perfect absorber is composed of a plurality of periodically arranged unit structures, each unit structure comprises a metal reflecting layer, a dielectric layer and a semiconductor material layer, and the metal reflecting layer, the dielectric layer and the semiconductor material layer are sequentially arranged from top to bottom. An air circular hole is dug in the middle of the semiconductor material layer, and the center of the air circular hole is different from that of the cube. By arranging a reflection metal layer and breaking the symmetry of a unit structure, resonance absorption peaks with two modes are realized, then the influence of structural geometric parameters on the double absorption peaks and the dependence of the two absorption peaks on the polarization direction of incident light are calculated, and the sensing performance of the double absorption peaks in different refractive index environments is calculated. The narrow-band dual-mode perfect absorber is simple in structure and convenient to regulate and control, achieves the narrow-band dual-mode perfect absorber, has good sensing performance, and provides reference for further research in the fields of multi-channel sensors, optical filters, thermophotovoltaics and the like.

Description

Technical Field

[0001] The present invention relates to the field of optical metasurfaces, and in particular to a dual-mode perfect absorber of a quasi-continuous domain bound-state all-dielectric metasurface and its application. Background Art

[0002] All-dielectric metasurfaces, with their advantages of low loss, excellent light field manipulation, and flexible design, are a research hotspot in micro- and nanophotonics. They achieve ultra-low-loss localized electromagnetic field enhancement through Mie resonance within high-refractive-index dielectric nanostructures. While all-dielectric metasurfaces based on symmetry-protected and accidental BICs can achieve high-Q resonances, the former is limited by structural symmetry, while the latter requires complex parameter manipulation, limiting design flexibility. Furthermore, BICs must be converted to QBICs through symmetry breaking or parameter manipulation to achieve efficient light field coupling.

[0003] Currently, QBIC-based metasurfaces mostly focus on single-frequency sensing or laser enhancement, and still face challenges in terms of multifunctional integration and single adaptation scenarios. Limited mode excitation: Traditional QBIC relies on symmetry-breaking parameters, such as nanostructure gap size or tilt angle control. A single metasurface usually only supports a single QBIC mode, making it difficult to achieve multi-modal independent excitation. Single frequency band response: Traditional QBIC absorption peaks can only achieve single perfect absorption and cannot meet the needs of multi-wavelength energy collection. The dynamic sensitivity and range of sensing detection are insufficient, and cannot meet the sensitivity detection requirements under perturbation conditions, as well as the needs of wide-range biochemical detection when the refractive index changes slightly. Therefore, it is very important to design an all-dielectric metasurface with a suitable structure to achieve multi-mode excitation and high-sensitivity sensing detection. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a dual-mode perfect absorber of a quasi-continuous domain bound state all-dielectric metasurface and its application.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a dual-mode perfect absorber of a quasi-continuous domain bound state all-dielectric metasurface, composed of a plurality of periodically arranged unit structures, each unit structure including a metal reflective layer, a dielectric layer and a semiconductor material layer, the metal reflective layer being selected from a material having high reflectivity and low loss in a specific band, and the structure of the metal reflective layer being a rectangular parallelepiped; the dielectric layer being arranged on the metal reflective layer, and being selected from a material having high transmittance, low absorption and low scattering in a specific band, the structure of the dielectric layer being consistent with that of the metal reflective layer, the dielectric layer being arranged on the metal reflective layer, and the semiconductor material layer being arranged in a cube on the dielectric layer, an air hole being dug out in the middle of the cube, and the center of the air hole being different from the center of the cube.

[0006] A further technical solution of the present invention is: the material of the metal reflective layer is selected from aluminum in the ultraviolet to visible light band, and is selected from gold, silver and / or copper in the visible to near-infrared band; the material of the dielectric layer is selected from calcium fluoride, magnesium fluoride or magnesium fluoride in the ultraviolet to mid-infrared band, and is selected from zinc sulfide, silicon dioxide or sapphire in the near-infrared to short-wave infrared band; the material of the semiconductor material layer is selected from silicon or germanium.

[0007] A further technical solution of the present invention is: the width of the metal reflective layer ranges from 800 to 1500 nm, the length ranges from 800 to 1500 nm, and the thickness ranges from 200 to 570 nm; the width of the dielectric layer ranges from 800 to 1500 nm, the length ranges from 800 to 1500 nm, and the thickness ranges from 200 to 570 nm; the side length of the cube ranges from 320 to 360 nm, the height ranges from 170 to 230 nm, the radius of the air hole ranges from 70 to 130 nm, and the distance between the center of the air hole and the center of the cube ranges from 0 to 20 nm.

[0008] A further technical solution of the present invention is: adding a super surface adjustable material layer in the middle of the semiconductor material layer.

[0009] A further technical solution of the present invention is that the material of the super surface adjustable material layer is vanadium dioxide, the thickness thereof is one tenth of the semiconductor material layer, and the position thereof is in the middle of the semiconductor material layer.

[0010] Another technical solution provided by the present invention is: the application of the dual-mode perfect absorber of the quasi-continuum bound state all-dielectric metasurface, the incident light of the dual-mode perfect absorber is in the Y-polarization direction, and is applied to air with an ambient refractive index of n=1.00 and water with an ambient refractive index of n=1.30.

[0011] A further technical solution of the present invention is that the sensitivities of the two absorption peaks of the dual-mode perfect absorber in air are 330 nm / RIU and 130 nm / RIU respectively, and the sensitivities of the two absorption peaks in water are 460 nm / RIU and 790 nm / RIU respectively.

[0012] Compared with the prior art, the present invention has the following characteristics:

[0013] (1) The present invention achieves a resonant absorption peak with two modes by providing a reflective metal layer in the metasurface and breaking the symmetry of the unit structure, one of which is the accidental BIC absorption peak and the other is the symmetry-protected accidental BIC, thus overcoming the deficiency of the traditional structure that only supports a single QBIC.

[0014] (2) The dual-mode perfect absorber of the present invention has high sensitivity and a simpler control method when used in environments with different refractive indices, which improves the defects of traditional sensing detection, such as insufficient dynamic sensitivity and range, as well as low sensitivity under perturbations. It has special applications in the fields of multi-channel sensors, optical filters, and thermophotovoltaics.

[0015] The detailed structure of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the dual-mode perfect absorber structure of the quasi-continuum bound-state all-dielectric metasurface;

[0017] Figures 2(a) and 2(b) are the side view and top view of the all-dielectric metasurface unit structure, respectively;

[0018] Figure 3 Reflection, transmission, and absorption spectra of the all-dielectric metasurface perfect absorber;

[0019] Figures 4(a) and 4(b) are the spectra and polar plots of the two absorption peaks when the polarization angle changes from 0° to 360°, respectively;

[0020] Figures 5(a), 5(b), and 5(c) are the corresponding absorption spectra when the side length, height, and air hole radius of the semiconductor material layer are changed;

[0021] Figure 6 The cross-sectional view, schematic diagram, and absorption spectrum comparison of the tunable narrowband dual-mode perfect absorber are shown;

[0022] Figures 7(a) and 7(b) are double resonance sensing images when Y-polarized light is incident in environments with different refractive indices;

[0023] Figures 8(a) and 8(b) are linear fitting diagrams of sensitivity under different refractive index environments. DETAILED DESCRIPTION

[0024] Example 1, as Figure 1 -2, a dual-mode perfect absorber of a quasi-continuous domain bound state all-dielectric metasurface is composed of a plurality of periodically arranged unit structures, each unit structure including a metal reflective layer 1, a dielectric layer 2 and a semiconductor material layer 3. The metal reflective layer 1 is selected to have a high reflectivity and low loss material in a specific band, such as aluminum in the ultraviolet to visible light band; gold, silver and / or copper in the visible to near-infrared band. The structure of the metal reflective layer 1 is a rectangular parallelepiped with a width P x The range is 800~1500nm, the length P yThe range is 800~1500nm, and the thickness H range is 280~570nm. The dielectric layer 2 is set on the metal reflective layer by etching or other means, and is selected from a material with high transmittance, low absorption, low scattering and other characteristics in a specific band, such as calcium fluoride, magnesium fluoride or magnesium fluoride in the ultraviolet to mid-infrared band; zinc sulfide, silicon dioxide or sapphire in the near infrared to short-wave infrared band. The structure of the dielectric layer 2 is consistent with that of the metal reflective layer, and is also a rectangular parallelepiped. Its width P x The range is 800~1500nm, the length P y The semiconductor material layer 3 is a cube 3-1 formed on a dielectric layer by etching or other means. The material is silicon, germanium, or other materials. An air hole 3-2 is dug out within the cube 3-1. The side length W of the cube 3-1 ranges from 320 to 360 nm, the thickness h ranges from 170 to 230 nm, the radius r of the air hole 3-2 ranges from 70 to 130 nm, and the distance between the center of the air hole 3-2 and the center of the cube 3-1 is δ.

[0025] In this embodiment, the absorption peak of the dual-mode perfect absorber is located in the near-infrared band, so the material of the metal reflective layer 1 is selected to be metal silver Ag, and the width P x The value is 1100nm, the length P y The value of is 1100nm, and the value of thickness H is 280nm. The material of dielectric layer 2 is calcium fluoride CaF2, and the width P x The value is 1100nm, the length P y The value of h1 is 1100 nm, and the value of thickness h1 is 280 nm. The semiconductor material layer 3 is made of germanium Ge, its side length W is 360 nm, its height h is 200 nm, the radius r of the air hole 3-2 is 100 nm, and the distance δ between the center of the air hole 3-2 and the center of the cube 3-1 is 18 nm.

[0026] The dual-mode perfect absorber of this quasi-continuum bound-state all-dielectric metasurface is defined by an X, Y, and Z Cartesian coordinate system, where the X and Y axes are the transverse and longitudinal array periodicity directions, respectively, and the Z axis is perpendicular to the plane formed by the X and Y axes. Incident light is incident perpendicularly from the semiconductor material layer 3 onto the bottom side of the dielectric layer 2 and reflected by the metal reflective layer 1. Monitors are placed above the semiconductor material layer 3 and below the metal reflective layer 1 of the dual-mode perfect absorber to observe the reflection and transmission spectra of the incident light after passing through the dual-mode perfect absorber. The incident light is selected to be a plane wave with Y polarization. Figure 3 The reflection, transmission, and absorption spectra of the dual-mode perfect absorber of the quasi-continuum bound-state all-dielectric metasurface of this embodiment are shown, where the absorptivity is calculated as follows:

[0027] A = 1 - R - T (1)

[0028] Wherein, A is the absorptivity of the dual-mode perfect absorber, R is the reflectivity of the dual-mode perfect absorber, and T is the transmittance of the dual-mode perfect absorber. Figure 3 It can be seen that the dual-mode perfect absorber of this embodiment exhibits two narrow-band absorption peaks at wavelengths of 1453.2 nm and 1587 nm, respectively. The full width at half wave (FWHM) of the two absorption peaks are 12 nm and 2 nm, respectively. The absorption peak at 1453.2 nm is due to the accidental quasi-BIC obtained by coupling the entire perfect absorber with the metal reflector Ag, and the narrow-band absorption peak at 1587 nm is achieved by the combined effect of the symmetric protection BIC and the accidental BIC generated by the distance between the center of the air hole 3-2 and the center of the cube 3-1.

[0029] To further verify the dependence of the absorption performance of the dual-mode perfect absorber on the polarization direction of the incident light, the incident light polarization angle was set to change from 0° to 360°. Figure 4 shows the absorption peak spectra and polar coordinate diagrams of the dual-mode perfect absorber of the quasi-continuum bound state all-dielectric metasurface of this embodiment under different polarization directions, where 0° and 180° are polarizations in the X direction, and 90° and 270° are polarizations in the Y direction. As can be seen from Figure 4(a), the absorption peak at a wavelength of 1453.2nm remains stable as the polarization angle changes, maintaining an absorptivity close to 1, which is independent of polarization. For the absorption peak at a wavelength of 1587nm, when the polarization angle changes from 0° to 180°, its absorptivity gradually increases and then decreases, reaching a maximum absorptivity at 90°, indicating that the absorption peak at this location is dependent on the Y polarization. Similarly, the polar coordinate diagram of the two absorption peaks in Figure 4(b) further proves that the absorptivity of the absorption peak at a wavelength of 1453.2 nm is independent of the polarization angle, that is, it is independent of polarization, while the absorptivity of the absorption peak at a wavelength of 1587 nm is related to polarization, and the absorptivity reaches its maximum when the incident light is polarized in the Y direction.

[0030] Example 2: The dual-mode perfect absorber of the quasi-continuous domain bound state all-dielectric metasurface of Example 2 is similar in structure to that of Example 1, except that the specific parameter values of the metal reflective layer 1, the dielectric layer 2 and the semiconductor material layer 3 are different. x The value is 800nm, the length P y The value of is 800nm, and the value of thickness H is 570nm. The width P of dielectric layer 2 is x The value is 800nm, the length P yThe value of is 800nm, the value of thickness h1 is 570nm. The value of side length W of semiconductor material layer 3 is 320nm, the value of height h is 170nm, the value of radius r of air hole 3-2 is 70nm, and the value of distance δ between the center of air hole 3-2 and the center of cube 3-1 is 5nm.

[0031] Example 3: The dual-mode perfect absorber of the quasi-continuous domain bound state all-dielectric metasurface of Example 3 is similar in structure to that of Example 1, except that the specific parameter values of the metal reflective layer 1, the dielectric layer 2 and the semiconductor material layer 3 are different. x The value is 1500nm, the length P y The value of is 1500nm, and the value of thickness H is 460nm. The width P of dielectric layer 2 is x The value is 1500nm, the length P y The value of is 1500nm, the value of thickness h1 is 460nm. The value of side length W of semiconductor material layer 3 is 340nm, the value of height h is 230nm, the value of radius r of air hole 3-2 is 130nm, and the value of distance δ between the center of air hole 3-2 and the center of cube 3-1 is 20nm.

[0032] Figures 5(a), 5(b), and 5(c) show the corresponding absorption spectra for changes in the side length W, height h, and air hole radius r of the semiconductor material layer 3. As shown in Figure 5(a), as the side length W changes from 330nm to 360nm, the change in side length W has little effect on the absorption performance of the absorption peak at a wavelength of 1453.2nm. This absorption peak reaches its maximum absorptivity at a side length of W = 360nm. However, changes in side length W have a particularly significant impact on the absorption performance of the absorption peak at a wavelength of 1587nm compared to the absorption peak at a wavelength of 1453.2nm. When W = 320nm, the absorptivity is only 0.3, but as W increases, the absorptivity gradually increases to 0.98, while also exhibiting a relatively narrow linewidth.

[0033] As can be seen from Figure 5(b), as the height h varies from 170nm to 230nm, the absorption peak at a wavelength of 1453.2nm reaches its maximum absorptivity at a height of h = 200nm. Increasing or decreasing the height h will reduce the absorptivity, affecting the absorber's performance. However, the absorption peak at a wavelength of 1587nm is different. When the height h begins to change, the absorptivity gradually increases. After increasing to a certain thickness, that is, h = 200nm, the absorptivity gradually decreases, but the impact is small, and the absorptivity remains relatively high.

[0034] As shown in Figure 5(c), as the air hole radius r changes from 70nm to 130nm, the change in air hole radius r has little effect on the absorption performance of the absorption peak at a wavelength of 1453.2nm. However, for the absorption peak at a wavelength of 1587nm, a smaller air hole radius r has a greater impact on this absorption peak, affecting not only the absorptivity but also the resonance position of the absorption peak. However, when the air hole radius r increases to a certain size, the absorption peak gradually decreases after reaching its maximum value as the air hole radius r continues to increase.

[0035] Example 4. The dual-mode perfect absorber of the quasi-continuous domain bound state all-dielectric metasurface of Example 4 is basically similar in structure to that of Example 1, the difference being that a metasurface adjustable material layer is added in the middle of the semiconductor material layer 3. This is because once the dual-mode perfect absorber of Example 1 is manufactured, the parameters of its unit structure are fixed, and its absorption performance is also fixed. When it is applied to different scenarios, it is difficult to adapt, and redesigning the unit structure parameters is not only time-consuming, but also increases costs. Therefore, in order to further improve the adaptation scenarios of the dual-mode perfect absorber, it is designed to add a metasurface adjustable material layer in the middle of the semiconductor material layer 3. The material of the metasurface adjustable material layer is selected differently according to different adjustable parameters. For example, vanadium dioxide or GST materials are selected to achieve temperature adjustment, and graphene or ITO materials are selected to achieve adjustable parameters such as voltage and current. In this embodiment, the temperature-adjustable non-volatile phase change material vanadium dioxide VO2 is selected and disposed in the middle of the semiconductor material layer 3 with a thickness of 20nm. Figure 6 The cross-sectional view of the dual-mode perfect absorber of the quasi-continuous domain bound state all-dielectric metasurface of this embodiment and the absorption spectra at different temperatures are shown. Figure 6 It can be seen that by setting the temperature of the vanadium dioxide VO2 material to 30° and 80° respectively, the vanadium dioxide VO2 material converts between the metallic state and the semiconductor state respectively. The dual-mode perfect absorber achieves an adjustable absorption rate from 0.41 to 0.96, and its maximum modulation depth reaches 130% by calculation.

[0036] Example 5. Application of the dual-mode perfect absorber of the quasi-continuous domain bound state all-dielectric metasurface of Examples 1 to 4. Optical refractive index sensing has always been one of the important applications of metasurface absorbers, and sensing sensitivity is an important metric. The dual-mode perfect absorber of the quasi-continuous domain bound state all-dielectric metasurface of Examples 1 to 4 overcomes the limitations of traditional single QBIC sensing, realizes dual-mode resonant sensing, and can better adapt to the variability of the environment. Figure 7 shows the dual-resonance sensing diagram under the condition of incident light in the Y-polarization direction, when the ambient refractive index is n = 1.00, that is, air and the ambient refractive index is n = 1.30. It can be seen from Figure 7 that with the change of the ambient refractive index n, the two absorption peaks gradually red-shift. For the case in air, when the ambient refractive index n changes from 1.00 to 1.05, the red-shift wavelength of the absorption peak at a wavelength of 1453.2nm is significantly larger than the absorption peak at a wavelength of 1587nm. However, for the case in aqueous solution, that is, when the ambient refractive index n changes from 1.30 to 1.35, the absorption peak at a wavelength of 1587nm can still maintain a large red shift while keeping the absorptivity unchanged.

[0037] Sensitivity S = Δλ / Δn is introduced to evaluate the performance of the dual-mode perfect absorber, and a linear fitting diagram of the sensitivity under different refractive index environments is obtained as shown in Figure 8. It can be seen from Figure 8 that the sensitivities of the two absorption peaks in air are 330nm / RIU and 130nm / RIU respectively, and the sensitivities of the two absorption peaks in water are 460nm / RIU and 790nm / RIU respectively, both of which realize a dual-resonance perfect absorber with high sensing sensitivity performance, which can have high sensing sensitivity to smile disturbances in different environments.

[0038] The above implementation cases reflect the application levels and occasions of the content of the present invention. As long as the technical solutions achieve the purpose of the present invention by basically the same means, they all fall within the scope of protection of the present invention.

Claims

1. A dual-mode perfect absorber based on a quasi-continuous bound-state all-dielectric metasurface, consisting of a plurality of periodically arranged unit structures, is characterized by: Each unit structure includes a metal reflective layer, a dielectric layer and a semiconductor material layer. The metal reflective layer is selected from a material with high reflectivity and low loss in a specific band, and the structure of the metal reflective layer is a rectangular parallelepiped; the dielectric layer is arranged on the metal reflective layer, and is selected from a material with high transmittance, low absorption and low scattering in a specific band. The structure of the dielectric layer is consistent with that of the metal reflective layer. The dielectric layer is arranged on the metal reflective layer, and the semiconductor material layer is arranged in a cube on the dielectric layer. An air hole is dug out in the middle of the cube, and the center of the air hole is different from the center of the cube.

2. The dual-mode perfect absorber of the quasi-continuum bound-state all-dielectric metasurface according to claim 1, characterized in that: The material of the metal reflective layer is selected from aluminum in the ultraviolet to visible light band, and gold, silver and / or copper in the visible to near-infrared band; the material of the dielectric layer is selected from calcium fluoride, magnesium fluoride or magnesium fluoride in the ultraviolet to mid-infrared band, and zinc sulfide, silicon dioxide or sapphire in the near-infrared to short-wave infrared band; the material of the semiconductor material layer is selected from silicon or germanium.

3. The dual-mode perfect absorber of the quasi-continuum bound-state all-dielectric metasurface according to claim 1, characterized in that: The width of the metal reflective layer ranges from 800 to 1500 nm, the length ranges from 800 to 1500 nm, and the thickness ranges from 200 to 570 nm; the width of the dielectric layer ranges from 800 to 1500 nm, the length ranges from 800 to 1500 nm, and the thickness ranges from 200 to 570 nm; the side length of the cube ranges from 320 to 360 nm, the height ranges from 170 to 230 nm, the radius of the air hole ranges from 70 to 130 nm, and the distance between the center of the air hole and the center of the cube ranges from 0 to 20 nm.

4. The dual-mode perfect absorber of the quasi-continuum bound-state all-dielectric metasurface according to claim 1, characterized in that: A super-surface tunable material layer is added in the middle of the semiconductor material layer.

5. The dual-mode perfect absorber of the quasi-continuum bound-state all-dielectric metasurface according to claim 4, characterized in that: The material of the super surface adjustable material layer is vanadium dioxide, the thickness of the layer is one tenth of the semiconductor material layer, and the layer is located in the middle of the semiconductor material layer.

6. Application of the dual-mode perfect absorber of the quasi-continuum bound-state all-dielectric metasurface according to any one of claims 1 to 5, characterized in that: The incident light of the dual-mode perfect absorber is in the Y-polarization direction and is applied to the ambient refractive index of air with n=1.00 and the ambient refractive index of water with n=1.

30.

7. Application of the dual-mode perfect absorber of the quasi-continuum bound-state all-dielectric metasurface according to claim 6, characterized in that: The sensitivities of the two absorption peaks of the dual-mode perfect absorber in air are 330nm / RIU and 130nm / RIU respectively, and the sensitivities of the two absorption peaks in water are 460nm / RIU and 790nm / RIU respectively.

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