Construction method of bipolarized full-angle minimal bragg surface super surface

Abstract

The application discloses a construction method of a bipolarized omnidirectional minimal Bruggert super surface, relates to the technical field of artificial electromagnetic super surfaces and electromagnetic wave regulation, and is based on the core phase condition of destructive reflection interference derived from a multiple interference theory to obtain the cause of angle instability of a central working frequency; through superposition of plasmonic oscillation effect and Lorentz resonance effect, the equivalent dielectric constant dispersion of a dielectric substrate loaded with a super surface is regulated, a minimal Bruggert super surface composed of a continuous metal grid and a metal rectangular patch is constructed, collaborative design of dispersion regulation parameters and structure iteration optimization are completed, the design effect is verified through full-wave simulation, high wave transmission of TE and TM dual-polarized electromagnetic waves is realized within the range of an incident angle, and the problem that the central working frequency deviates with the incident angle is solved.

Description

Technical Field

[0001] This invention relates to the field of artificial electromagnetic metasurfaces and electromagnetic wave manipulation technology, specifically a method for constructing a minimally simplistic Brewster metasurface based on dual-polarization full-angle. Background Technology

[0002] In 1810, Sir David Brewster discovered that total transmission occurs when a transversely magnetically polarized electromagnetic wave is incident on a medium at a specific angle of incidence. This phenomenon was later called the Brewster effect, and the corresponding angle of incidence is called the Brewster angle. The underlying principle of the Brewster effect is impedance matching between the medium and the air. According to Snell's law, this impedance matching phenomenon only exists at a specific incident angle under TM polarization. This limitation restricts the development of the Brewster effect in academic and applied fields.

[0003] Metamaterials, and their special two-dimensional counterparts called metasurfaces, have attracted much attention in recent years due to their electromagnetic manipulation capabilities. Researchers have achieved impedance matching at various polarizations and angles in metasurfaces. These phenomena are known as the generalized Brewster effect, and the corresponding metasurfaces are called Brewster metasurfaces. In 2022, Cheng Jin et al. achieved an ultrawide-angle GBE under transverse polarization.

[0004] Although GBE has been extensively studied, it has not solved the limitations of the traditional Brewster effect: no relevant GBE studies have been able to achieve GBE that is applicable to both bipolarization and full-angle applications; most Brewster metasurfaces have complex structures that are difficult to match with current processing techniques. Summary of the Invention

[0005] The purpose of this invention is to provide a simplified Brewster metasurface construction method based on dual polarization and full angularity, in order to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for constructing a minimally simplistic Brewster metasurface based on dual-polarization full-angle, the method comprising the following steps: Step S100: Define basic electromagnetic parameters, with medium 1 representing air and medium 2 representing the dielectric substrate. The relative permittivity of air is ε1 and the relative permeability is μ1, while the relative permittivity of the dielectric substrate is ε2 and the relative permeability is μ2. The dielectric substrate refers to a medium with a minimal Brewster metasurface attached, which needs to achieve dual-polarization full-angle high wave transmission performance. The refractive indices of air and the dielectric substrate respectively satisfy... , ; Based on the theory of multiple interference, the time delay phase φ between the reflected waves after an electromagnetic wave is incident on a dielectric substrate is derived, and the calculation formula is as follows: ; In the formula, θ1 is the incident angle of the electromagnetic wave in the air, f is the frequency of the electromagnetic wave, c0 is the speed of light in a vacuum, and d is the thickness of the dielectric substrate. Based on the interference superposition of reflected waves, the formula for the total reflectivity of the dielectric substrate under TE / TM polarization is derived as follows: ; In the formula, the superscript TE / TM indicates that the formula applies to both transverse electric (TE) polarization and transverse magnetic (TM) polarization. When TE polarization is selected, all physical quantities marked with TE / TM in the formula are: R TE / TM r 12 TE / TM r 21 TE / TM t 21 TE / TM t 21 TE / TM All quantities are simultaneously assigned the superscript TE; when TM polarization is selected, all physical quantities in the formula marked with TE / TM are simultaneously assigned the superscript TM; where r 12 TE / TM Let t be the TE / TM polarization reflection coefficient when the electromagnetic wave propagates from medium 1 to medium 2, and t be the corresponding TE / TM polarization transmission coefficient. 12 TE / TM ;r 21 TE / TM Let t be the TE / TM polarization reflection coefficient when the electromagnetic wave propagates from medium 2 to medium 1, and t be the corresponding TE / TM polarization transmission coefficient. 21 TE / TM ; r 12 TE / TM and r 21 TE / TM The expression based on Snell's law is: ; ; In the formula, the superscript TE / TM indicates that the formula applies to both transverse electric (TE) polarization and transverse magnetic (TM) polarization. When TE polarization is selected, all physical quantities marked with TE / TM in the formula are: r 12 TE / TM r 21 TE / TM Z1 TE / TM Z2 TE / TM All quantities are simultaneously marked with the superscript TE; when TM polarization is selected, all physical quantities marked with TE / TM in the formula are simultaneously marked with the superscript TM. Z1 TE / TM The wave impedance of medium 1 under TE / TM polarization is calculated using the following formula: ; ; Z2 TE / TM The wave impedance of dielectric 2 under TE / TM polarization is calculated using the following formula: ; ; In the formula, θ2 is the angle of refraction of the electromagnetic wave in the dielectric substrate. ; Based on the above formula, the total reflectance R TE / TM Simplified to: ; According to the law of conservation of energy, neglecting electromagnetic losses, a transparent window is equivalent to R. TE / TM =0, the transparent window represents the electromagnetic wave operating frequency band with zero reflectivity when the incident electromagnetic wave irradiates the dielectric substrate loaded with the minimal Brewster metasurface. This method achieves this condition through destructive reflection interference. For lossless media, the reflection coefficient satisfies Substituting into the reflectance formula, it can be simplified to 1-e -2jφ =0, corresponding to the core phase condition: φ = mπ, (m = 0, 1, 2...); In the formula, m is the integer order of φ = mπ; Substituting the delayed phase φ into the core phase condition, the realization condition of destructive reflection interference can be expressed as: ; The realization conditions of the destructive reflection interference can be expressed as the formula, where the left side of the formula is a function of f and θ1, and the right side is a constant. When θ1 increases, f increases accordingly, and conversely, when θ1 decreases, f decreases accordingly. It can be determined that the center working frequency of the destructive reflection interference will shift with the incident angle, exhibiting angular instability. The center working frequency refers to the optimal frequency point that allows the electromagnetic wave to pass through completely.

[0007] Step S200: In order to keep the center operating frequency constant under different incident angles θ1, the equivalent dielectric constant ε2(f) after loading the metasurface onto the dielectric substrate is dispersion-tuned so that ε2(f) is a function that increases with f. The dispersion tuning is achieved by superimposing the plasmonic oscillation effect and the Lorentz resonance effect. The dielectric constant dispersion formulas corresponding to the two effects are the plasmonic oscillation effect formula and the Lorentz resonance effect formula, respectively. The formula for the plasma-like oscillation effect is as follows: ; In the formula, f0 is the normalized electromagnetic wave frequency, i is the imaginary unit, γ is the electromagnetic loss, characterizing the electromagnetic wave energy loss between the metasurface and the dielectric substrate, and f P The plasma-like frequency is the characteristic frequency of plasma-like oscillations excited by metasurfaces. The Lorentz resonance effect formula is as follows: ; In the formula, A is the resonance intensity constant, f1 is the resonance frequency, which is the inherent center operating frequency of the Lorentz resonance; By superimposing the dispersion characteristics of the two effects, the equivalent dielectric constant ε2(f) exhibits an ideal characteristic of increasing with frequency at the center operating frequency, thus compensating for the influence of the incident angle change on φ.

[0008] Step S300: Construct a minimal Brewster metasurface loaded on one side of a dielectric substrate. The minimal Brewster metasurface consists of a continuous metal mesh and metal rectangular patches arranged on the same side of the dielectric substrate. The core parameters of the unit structure are defined as follows: the unit period is p, the side length of the metal rectangular patch is a, the line width of the metal mesh is w, and the thickness of the dielectric substrate is d. The unit period refers to the period of the periodically arranged unit structure of the metasurface in the x and y directions. The metal mesh is used to excite a low-frequency plasma-like oscillation effect, while the metal rectangular patch acts as an electric resonator to excite a high-frequency Lorentz resonance effect.

[0009] Step S400: Complete the collaborative design of dispersion control parameters for the metasurface structure, specifically as follows: Parameter design of the metal mesh: By adjusting the linewidth w and cell period p of the metal mesh, the plasma-like frequency f is controlled. P This ensures that the working frequency band of the plasma-like oscillation effect is located in the low frequency band of the center working frequency, thus guaranteeing the formation of the basic dispersion characteristic ε2(f) that increases with frequency at the center working frequency. The parameters of the metal rectangular patch are designed as follows: By adjusting the side length a and the unit period p of the metal rectangular patch, the resonant frequency f1 is controlled so that the operating frequency band of the Lorentz resonance effect is located in the high frequency band of the center operating frequency, and in the operating frequency band below the resonant frequency f1. The equivalent dielectric constant ε2(f) after loading the metasurface onto the dielectric substrate exhibits an ideal frequency-increasing characteristic at the center operating frequency, satisfying the phase stability condition for destructive reflection interference at all angles.

[0010] Step S500: Based on the core phase condition of destructive reflection interference, and combined with the equivalent dielectric constant ε2(f) after dispersion modulation, the structural parameters of the metasurface are iteratively optimized, specifically as follows: Within the incident angle θ1 ∈ [0°, 80°], adjust the structural parameters a, p, and w so that both TE-polarized and TM-polarized electromagnetic waves satisfy the phase condition φ = mπ at the center operating frequency, thereby maximizing the total reflectivity R. TE / TM =0, achieving full transmission; During the iterative optimization process, the stability of different incident angles and center operating frequencies is verified simultaneously to ensure that the transmittance at the center operating frequency meets the design threshold under both TE and TM polarization within the range of θ1∈[0°,80°]. The design threshold is set by professionals.

[0011] Step S600: Use electromagnetic simulation software to perform full-wave simulation on the optimized metasurface structure. The simulation boundary conditions are set as follows: the magnetic fields of TE polarization and TM polarization are along the y-axis at all incident angles, the incident angle scanning range is 0° to 80°, and the frequency scanning range covers the plasma-like oscillation frequency band, the central working frequency band and the Lorentz resonant frequency band. Transmission and reflection spectra under TE and TM polarizations were extracted through full-wave simulation to verify the transmission peak and reflection zero at the center operating frequency. When the simulation results did not meet the design target, the parameter values ​​of metal mesh linewidth w, metal rectangular patch side length a, and element period p were iteratively adjusted, and the simulation verification process was repeated until the design requirements were met.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. Breaking through the limitations of the traditional Brewster effect and achieving a perfect Brewster effect with dual polarization at all angles: This invention uses a destructive interference mechanism based on reflection to achieve electromagnetic transparency, breaking the limitation of the traditional Brewster effect being only applicable to a single polarization and a specific incident angle. It can simultaneously adapt to both transverse electric and transverse magnetic dual polarized electromagnetic waves, achieving stable electromagnetic transparency over a wide range of incident angles.

[0013] 2. The metasurface structure design is simple and reduces the difficulty of fabrication: The Brewster metasurface designed in this invention only requires the core functional units to be arranged on one side of the dielectric substrate. It does not require the complex structure of multi-layer dielectric stacking, double-sided substrate patterning, and embedded vias required by traditional solutions, which simplifies the fabrication process and reduces the production cost and process threshold.

[0014] 3. It has universal applicability and can adapt to the application needs of multiple frequency bands: By adjusting the structural parameters, this invention can adapt to dielectric substrates of different materials and thicknesses to meet the differentiated use needs of different application scenarios. Attached Figure Description

[0015] Figure 1This is a schematic diagram of the structure of the minimalist Brewster metasurface construction method based on dual-polarization full-angle of the present invention; Figure 2 This is a schematic diagram of the dual-polarized transmission and reflection spectra of a 4mm thick CMC substrate in the present invention's simplified Brewster metasurface construction method based on dual-polarization full-angle; Figure 3 This is a schematic diagram of the dual-polarized transmission and reflection spectra of a 10mm thick CMC substrate in the minimally simplified Brewster metasurface construction method based on dual polarization at all angles of the present invention. Detailed Implementation

[0016] 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.

[0017] Example: Figures 1-3 As shown, this invention provides a technical solution based on a simplified Brewster metasurface construction method with dual polarization and full angular range. The method includes the following steps: Step S100: Define basic electromagnetic parameters, with medium 1 representing air and medium 2 representing the dielectric substrate. The relative permittivity of air is ε1 and the relative permeability is μ1, while the relative permittivity of the dielectric substrate is ε2 and the relative permeability is μ2. The dielectric substrate refers to a medium with a minimal Brewster metasurface attached, which needs to achieve dual-polarization full-angle high wave transmission performance. The refractive indices of air and the dielectric substrate respectively satisfy... , ; Based on the theory of multiple interference, the time delay phase φ between the reflected waves after an electromagnetic wave is incident on a dielectric substrate is derived, and the calculation formula is as follows: ; In the formula, θ1 is the incident angle of the electromagnetic wave in the air, f is the frequency of the electromagnetic wave, c0 is the speed of light in a vacuum, and d is the thickness of the dielectric substrate. Based on the interference superposition of reflected waves, the formula for the total reflectivity of the dielectric substrate under TE / TM polarization is derived as follows: ; In the formula, the superscript TE / TM indicates that the formula applies to both transverse electric (TE) polarization and transverse magnetic (TM) polarization. When TE polarization is selected, all physical quantities marked with TE / TM in the formula are: R TE / TM r 12 TE / TM r 21 TE / TMt 21 TE / TM t 21 TE / TM All quantities are simultaneously assigned the superscript TE; when TM polarization is selected, all physical quantities in the formula marked with TE / TM are simultaneously assigned the superscript TM; where r 12 TE / TM Let t be the TE / TM polarization reflection coefficient when the electromagnetic wave propagates from medium 1 to medium 2, and t be the corresponding TE / TM polarization transmission coefficient. 12 TE / TM ;r 21 TE / TM Let t be the TE / TM polarization reflection coefficient when the electromagnetic wave propagates from medium 2 to medium 1, and t be the corresponding TE / TM polarization transmission coefficient. 21 TE / TM ; r 12 TE / TM and r 21 TE / TM The expression based on Snell's law is: ; ; In the formula, the superscript TE / TM indicates that the formula applies to both transverse electric (TE) polarization and transverse magnetic (TM) polarization. When TE polarization is selected, all physical quantities marked with TE / TM in the formula are: r 12 TE / TM r 21 TE / TM Z1 TE / TM Z2 TE / TM All quantities are simultaneously marked with the superscript TE; when TM polarization is selected, all physical quantities marked with TE / TM in the formula are simultaneously marked with the superscript TM. Z1 TE / TM The wave impedance of medium 1 under TE / TM polarization is calculated using the following formula: ; ; Z2 TE / TM The wave impedance of dielectric 2 under TE / TM polarization is calculated using the following formula: ; ; In the formula, θ2 is the angle of refraction of the electromagnetic wave in the dielectric substrate. ; Based on the above formula, the total reflectance R TE / TM Simplified to: ; According to the law of conservation of energy, neglecting electromagnetic losses, a transparent window is equivalent to R. TE / TM =0, the transparent window represents the electromagnetic wave operating frequency band with zero reflectivity when the incident electromagnetic wave irradiates the dielectric substrate loaded with the minimal Brewster metasurface. This method achieves this condition through destructive reflection interference. For lossless media, the reflection coefficient satisfies Substituting into the reflectance formula, it can be simplified to 1-e -2jφ =0, corresponding to the core phase condition: φ = mπ, (m = 0, 1, 2...); In the formula, m is the integer order of φ = mπ; Substituting the delayed phase φ into the core phase condition, the realization condition of destructive reflection interference can be expressed as: ; The realization conditions of the destructive reflection interference can be expressed as the formula, where the left side of the formula is a function of f and θ1, and the right side is a constant. When θ1 increases, f increases accordingly, and conversely, when θ1 decreases, f decreases accordingly. It can be determined that the center working frequency of the destructive reflection interference will shift with the incident angle, exhibiting angular instability. The center working frequency refers to the optimal frequency point that allows the electromagnetic wave to pass through completely.

[0018] Step S200: In order to keep the center operating frequency constant under different incident angles θ1, the equivalent dielectric constant ε2(f) after loading the metasurface onto the dielectric substrate is dispersion-tuned so that ε2(f) is a function that increases with f. The dispersion tuning is achieved by superimposing the plasmonic oscillation effect and the Lorentz resonance effect. The dielectric constant dispersion formulas corresponding to the two effects are the plasmonic oscillation effect formula and the Lorentz resonance effect formula, respectively. The formula for the plasma-like oscillation effect is as follows: ; In the formula, f0 is the normalized electromagnetic wave frequency, i is the imaginary unit, γ is the electromagnetic loss, characterizing the electromagnetic wave energy loss between the metasurface and the dielectric substrate, and f P The plasma-like frequency is the characteristic frequency of plasma-like oscillations excited by metasurfaces. The Lorentz resonance effect formula is as follows: ; In the formula, A is the resonance intensity constant, f1 is the resonance frequency, which is the inherent center operating frequency of the Lorentz resonance; By superimposing the dispersion characteristics of the two effects, the equivalent dielectric constant ε2(f) exhibits an ideal characteristic of increasing with frequency at the center operating frequency, thus compensating for the influence of the incident angle change on φ.

[0019] Step S300: Construct a minimal Brewster metasurface loaded on one side of a dielectric substrate. The minimal Brewster metasurface consists of a continuous metal mesh and metal rectangular patches arranged on the same side of the dielectric substrate. The core parameters of the unit structure are defined as follows: the unit period is p, the side length of the metal rectangular patch is a, the line width of the metal mesh is w, and the thickness of the dielectric substrate is d. The unit period refers to the period of the periodically arranged unit structure of the metasurface in the x and y directions. The metal mesh is used to excite a low-frequency plasma-like oscillation effect, while the metal rectangular patch acts as an electric resonator to excite a high-frequency Lorentz resonance effect.

[0020] Step S400: Complete the collaborative design of dispersion control parameters for the metasurface structure, specifically as follows: Parameter design of the metal mesh: By adjusting the linewidth w and cell period p of the metal mesh, the plasma-like frequency f is controlled. P This ensures that the working frequency band of the plasma-like oscillation effect is located in the low frequency band of the center working frequency, thus guaranteeing the formation of the basic dispersion characteristic ε2(f) that increases with frequency at the center working frequency. The parameters of the metal rectangular patch are designed as follows: By adjusting the side length a and the unit period p of the metal rectangular patch, the resonant frequency f1 is controlled so that the operating frequency band of the Lorentz resonance effect is located in the high frequency band of the center operating frequency, and in the operating frequency band below the resonant frequency f1. The equivalent dielectric constant ε2(f) after loading the metasurface onto the dielectric substrate exhibits an ideal frequency-increasing characteristic at the center operating frequency, satisfying the phase stability condition for destructive reflection interference at all angles.

[0021] Step S500: Based on the core phase condition of destructive reflection interference, and combined with the equivalent dielectric constant ε2(f) after dispersion modulation, the structural parameters of the metasurface are iteratively optimized, specifically as follows: Within the incident angle θ1 ∈ [0°, 80°], adjust the structural parameters a, p, and w so that both TE-polarized and TM-polarized electromagnetic waves satisfy the phase condition φ = mπ at the center operating frequency, thereby maximizing the total reflectivity R. TE / TM =0, achieving full transmission; During the iterative optimization process, the stability of different incident angles and center operating frequencies is verified simultaneously to ensure that the transmittance at the center operating frequency meets the design threshold under both TE and TM polarization within the range of θ1∈[0°,80°]. The design threshold is set by professionals.

[0022] Step S600: Use electromagnetic simulation software to perform full-wave simulation on the optimized metasurface structure. The simulation boundary conditions are set as follows: the magnetic fields of TE polarization and TM polarization are along the y-axis at all incident angles, the incident angle scanning range is 0° to 80°, and the frequency scanning range covers the plasma-like oscillation frequency band, the central working frequency band and the Lorentz resonant frequency band. Transmission and reflection spectra under TE and TM polarizations were extracted through full-wave simulation to verify the transmission peak and reflection zero at the center operating frequency. When the simulation results did not meet the design target, the parameter values ​​of metal mesh linewidth w, metal rectangular patch side length a, and element period p were iteratively adjusted, and the simulation verification process was repeated until the design requirements were met. Example 1:

[0023] Design object: 4mm thick minimalist Brewster metasurface loading medium plate; Core design specification: Center operating frequency f B =24.2GHz; Fixed basic parameters: Medium 1 is air, with relative permittivity ε1=1 and relative permeability μ1=1; Medium 2 is a CMC dielectric substrate, with relative permittivity ε2=3.4 and relative permeability μ2=1.0, substrate thickness d=4mm; speed of light in vacuum c0=3×10 × 8 m / s, vacuum wave impedance η0=377Ω; design with no electromagnetic loss; Based on the superposition of dual effects, the dielectric constant dispersion control design was carried out. In order to achieve a constant center operating frequency of 24.2GHz under all incident angles, the dispersion control of the equivalent dielectric constant ε2(f) of the dielectric substrate after loading MBM was performed. By superimposing the dispersion characteristics of the plasma-like oscillation effect and the Lorentz resonance effect, ε2(f) exhibits an ideal characteristic of increasing with frequency at 24.2GHz, which compensates for the influence of the incident angle change on the delay phase and cancels the angular shift of the center operating frequency. The MBM dispersion control parameters were designed collaboratively. The metal mesh linewidth w and element period p were adjusted to control the plasma-like frequency, so that the plasma-like oscillation effect operated in the low-frequency band of 24.2 GHz, forming the basic dispersion characteristic of ε2(f) increasing with frequency. The side length a and element period p of the metal rectangular patch were adjusted so that the resonance effect operated in the high-frequency band of 24.2 GHz and the operating frequency band was lower than the resonance frequency. The element structure parameters a, p, and w were iteratively optimized in the range of θ1∈[0°,80°], and w=0.8, p=4.25, and a=1.8 were obtained. like Figure 2As shown, full-wave simulation was performed on the optimized 4mm thick MBM-loaded plate using electromagnetic simulation software. The TE / TM polarization magnetic field was set along the y-axis at full incident angle, with an incident angle scan range of 0° to 80°. The frequency scan covered the entire frequency band of plasma-like oscillation, 24.2GHz center operation, and Lorentz resonance. The TE / TM polarization transmission and reflection spectra were extracted, and the transmission peak and reflection null point at 24.2GHz were verified, yielding the results of dual polarization at f B Transmittance > 90.8%, PBE center frequency relative frequency shift < 0.006%; Figure 2 In the figure, Figure (a) shows the TE polarization transmission spectrum of a 4mm thick MBM loaded plate at θ1=0°, 20°, 40°, 60°, and 80°; Figure (b) shows the TM polarization transmission spectrum of a 4mm thick MBM loaded plate at θ1=0°, 20°, 40°, 60°, and 80°; Figure (c) shows the TE polarization reflection spectrum of a 4mm thick MBM loaded plate at θ1=0°, 20°, 40°, 60°, and 80°; and Figure (d) shows the TM polarization reflection spectrum of a 4mm thick MBM loaded plate at θ1=0°, 20°, 40°, 60°, and 80°. Example 2:

[0024] Design object: CMC substrate, relative permittivity ε2=3.4, relative permeability μ2=1.0, thickness d=10mm; Core design specification: Center operating frequency f B =9.7GHz, iterative optimization of unit structure parameters a, p, w yielded 1.6, 10.5, 2.2; like Figure 3 As shown, Figure (a) shows the TE polarization transmission spectrum of a 10mm thick MBM-loaded plate at θ1=0°, 20°, 40°, 60°, and 80°; Figure (b) shows the TM polarization transmission spectrum of a 10mm thick MBM-loaded plate at θ1=0°, 20°, 40°, 60°, and 80°; Figure (c) shows the TE polarization reflection spectrum of a 10mm thick MBM-loaded plate at θ1=0°, 20°, 40°, 60°, and 80°; and Figure (d) shows the TM polarization reflection spectrum of a 10mm thick MBM-loaded plate at θ1=0°, 20°, 40°, 60°, and 80°. The TE / TM dual polarization transmittance is always >84.2%, and the relative frequency shift of the center frequency is <0.01%.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A simplified Brewster metasurface construction method based on dual-polarization full-angle, characterized in that: The method includes the following steps: Step S100: Define basic electromagnetic parameters, derive and simplify the delay phase of electromagnetic wave incident and the total reflectivity formula of dielectric substrate under TE / TM polarization based on multiple interference theory, obtain the core phase condition of destructive reflection interference based on the law of energy conservation, and determine whether the center working frequency will shift with the incident angle when there is no control. Step S200: Dispersion modulation is carried out on the equivalent dielectric constant after loading the metasurface onto the dielectric substrate. By superimposing the dispersion characteristics of the two effects of plasmonic oscillation and Lorentz resonance, the equivalent dielectric constant increases with frequency at the center operating frequency, compensating for the influence of the incident angle change on the phase. Step S300: Construct a minimal Brewster metasurface loaded on one side of the dielectric substrate and define the core parameters of the unit structure; Step S400: Complete the collaborative design of dispersion control parameters for the metasurface structure, wherein the collaborative design includes the parameter design of the metal mesh and the parameter design of the metal rectangular patch; Step S500: Based on the core phase condition of destructive reflection interference and combined with the equivalent dielectric constant after dispersion modulation, the structural parameters of the metasurface are iteratively optimized. Step S600: Perform full-wave simulation on the optimized metasurface structure, extract the transmission and reflection spectra under TE and TM polarization to verify the design effect, and iterate and adjust until the design requirements are met if the target is not achieved.

2. The method for constructing a minimalist Brewster metasurface based on dual polarization across all angles according to claim 1, characterized in that: The basic electromagnetic parameters defined in step S100 are as follows: Let medium 1 represent air and medium 2 represent a dielectric substrate. The dielectric substrate refers to a medium with a minimal Brewster metasurface attached and which needs to achieve dual-polarization full-angle high wave transmission performance. The refractive indices of air and dielectric substrate are n1 and n2, respectively. Based on the theory of multiple interference, the time delay phase φ between the reflected waves after an electromagnetic wave is incident on a dielectric substrate is derived. Based on the interference superposition of the reflected waves, the formula for the total reflectivity R of the dielectric substrate under TE / TM polarization is derived. TE / TM ; According to the law of conservation of energy, neglecting electromagnetic losses, a transparent window is equivalent to R. TE / TM =0, the transparent window represents the electromagnetic wave operating frequency band with zero reflectivity when incident electromagnetic waves irradiate the dielectric substrate loaded with the minimal Brewster metasurface, and the reflectivity formula can be simplified to 1-e -2jφ =0, corresponding to the core phase condition: φ = mπ, (m = 0, 1, 2...); In the formula, m is the integer order of φ = mπ; Substituting the delayed phase φ into the core phase condition, the realization condition of destructive reflection interference can be expressed as: ； The realization conditions of the destructive reflection interference can be expressed as follows: it can be determined that the center working frequency based on the destructive reflection interference will shift with the incident angle, exhibiting angular instability. The center working frequency refers to the optimal frequency point that allows the electromagnetic wave to pass through completely.

3. The method for constructing a minimalist Brewster metasurface based on dual polarization across all angles according to claim 1, characterized in that: In step S200, in order to keep the center operating frequency constant under different incident angles θ1, the equivalent dielectric constant ε2(f) after loading the metasurface onto the dielectric substrate is dispersion-controlled. The dispersion control is achieved by superimposing the plasmonic oscillation effect and the Lorentz resonance effect. By superimposing the dispersion characteristics of the two effects, the equivalent dielectric constant ε2(f) exhibits an ideal characteristic of increasing with frequency at the center operating frequency, thus compensating for the influence of the incident angle change on φ.

4. The method for constructing a minimalist Brewster metasurface based on dual polarization across all angles according to claim 1, characterized in that: In step S300, the minimalist Brewster metasurface is composed of a continuous metal mesh and metal rectangular patches, arranged on the same side surface of the dielectric substrate. The core parameters of the unit structure are defined as follows: the unit period is p, the side length of the metal rectangular patch is a, the line width of the metal mesh is w, and the thickness of the dielectric substrate is d. The unit period refers to the period of the periodically arranged unit structure of the metasurface in the x and y directions.

5. The method for constructing a minimalist Brewster metasurface based on dual polarization across all angles according to claim 1, characterized in that: In step S400, the parameter design of the metal mesh and the parameter design of the metal rectangular patch are specifically as follows: The plasma-like frequency f is controlled by adjusting the linewidth w and the unit period p of the metal mesh. P This allows the operating frequency band of the plasma-like oscillation effect to be located in the low-frequency band of the center operating frequency; By adjusting the side length 'a' and the unit period 'p' of the metal rectangular patch, the resonant frequency 'f1' is controlled, so that the operating frequency band of the Lorentz resonance effect is located in the high-frequency band of the center operating frequency, and within the operating frequency band below the resonant frequency 'f1'.

6. The method for constructing a minimalist Brewster metasurface based on dual polarization across all angles according to claim 1, characterized in that: In step S500, the iterative optimization specifically includes: Within the incident angle θ1 ∈ [0°, 80°], adjust the structural parameters a, p, and w so that both TE-polarized and TM-polarized electromagnetic waves satisfy the phase condition φ = mπ at the center operating frequency, thereby maximizing the total reflectivity R. TE / TM =0, achieving full transmission.

7. The method for constructing a minimalist Brewster metasurface based on dual polarization across all angles according to claim 1, characterized in that: The simulation boundary conditions for the full-wave simulation are set as follows: the magnetic fields of TE polarization and TM polarization are along the y-axis at all incident angles, the incident angle scanning range is 0° to 80°, and the frequency scanning range covers the plasma-like oscillation frequency band, the central working frequency band, and the Lorentz resonant frequency band. The transmission and reflection spectra under TE and TM polarizations were extracted by full-wave simulation to verify the transmission peak and reflection zero at the center operating frequency. When the simulation results did not meet the design target, the parameter values ​​of metal mesh linewidth w, metal rectangular patch side length a, and element period p were iteratively adjusted, and the full-wave simulation verification process was repeated until the design requirements were met.

8. The method for constructing a minimalist Brewster metasurface based on dual polarization across all angles according to claim 2, characterized in that: The derivation formula for the delay phase φ between the reflected waves is as follows: ； In the formula, θ1 is the incident angle of the electromagnetic wave in the air, f is the frequency of the electromagnetic wave, c0 is the speed of light in a vacuum, and d is the thickness of the dielectric substrate. Based on the interference superposition of reflected waves, the formula for the total reflectivity of the dielectric substrate under TE / TM polarization is derived as follows: ； In the formula, the superscript TE / TM indicates that the formula applies to both transverse electric (TE) polarization and transverse magnetic (TM) polarization. When TE polarization is selected, all physical quantities marked with TE / TM in the formula are: R TE / TM r 12 TE / TM r 21 TE / TM t 21 TE / TM t 21 TE / TM All quantities are simultaneously assigned the superscript TE; when TM polarization is selected, all physical quantities in the formula marked with TE / TM are simultaneously assigned the superscript TM; where r 12 TE / TM Let t be the TE / TM polarization reflection coefficient when the electromagnetic wave propagates from medium 1 to medium 2, and t be the corresponding TE / TM polarization transmission coefficient. 12 TE / TM ;r 21 TE / TM Let t be the TE / TM polarization reflection coefficient when the electromagnetic wave propagates from medium 2 to medium 1, and t be the corresponding TE / TM polarization transmission coefficient. 21 TE / TM ; r 12 TE / TM and r 21 TE / TM The expression based on Snell's law is: ； ； In the formula, the superscript TE / TM indicates that the formula applies to both transverse electric (TE) polarization and transverse magnetic (TM) polarization. When TE polarization is selected, all physical quantities marked with TE / TM in the formula are: r 12 TE / TM r 21 TE / TM Z1 TE / TM Z2 TE / TM All quantities are simultaneously marked with the superscript TE; when TM polarization is selected, all physical quantities marked with TE / TM in the formula are simultaneously marked with the superscript TM. Z1 TE / TM The wave impedance of medium 1 under TE / TM polarization is calculated using the following formula: ； ； Z2 TE / TM The wave impedance of dielectric 2 under TE / TM polarization is calculated using the following formula: ； ； In the formula, θ2 is the angle of refraction of the electromagnetic wave in the dielectric substrate. ; Based on the above formula, the total reflectance R TE / TM Simplified to: 。 9. The method for constructing a minimalist Brewster metasurface based on dual polarization across all angles according to claim 3, characterized in that: The formula for the plasma-like oscillation effect is as follows: ； In the formula, f0 is the normalized electromagnetic wave frequency, i is the imaginary unit, γ is the electromagnetic loss, characterizing the electromagnetic wave energy loss between the metasurface and the dielectric substrate, and f P The plasma-like frequency is the characteristic frequency of plasma-like oscillations excited by metasurfaces. The Lorentz resonance effect formula is as follows: ； In the formula, A is the resonance intensity constant, f1 is the resonance frequency, and f1 is the inherent center operating frequency of the Lorentz resonance.

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