An electromagnetic flatband for fano resonance detection and having significant robustness

Abstract

The application discloses an electromagnetic flat band for Fano resonance detection and with significant robustness, a plurality of first patterns and a plurality of second patterns are plated on the surface of an electrolyte substrate, and all the first patterns and all the second patterns are periodically arranged on the electrolyte substrate, the first pattern is a vertical pattern formed by rotating the second pattern by 90 DEG, and the material of the first pattern and the second pattern is metal. The electrolyte substrate is used as a support substrate, two groups of mutually perpendicular metal structures are prepared on the electrolyte substrate, a specific electromagnetic coupling effect is formed through the orthogonal arrangement of the metal structures, and then an optical flat band is stably generated. Different from the design of the existing single metal mode or non-orthogonal metal structure, the application can strictly control the vertical arrangement angle, size parameter and distribution density of the two groups of metal, so that the synergistic coupling effect is generated between the metal structures, the controllable generation of the optical flat band is realized, and the spectral characteristics of the flat band can be stably maintained.

Description

Technical Field

[0001] This invention belongs to the technical field of physical experimental instruments, and specifically relates to an electromagnetic flat band that is used for Fano resonance detection and has significant robustness. Background Technology

[0002] The Fano resonance is an asymmetric resonance phenomenon formed by the interference of discrete resonant states and continuous excited states. Unlike the symmetric Lorentz resonance, its spectrum exhibits a typical asymmetric line shape, possessing both a high quality factor and a narrow resonance linewidth. Its physical mechanism can be clearly explained through the coupled harmonic oscillator model and it is widely found in optics, electromagnetism, and other fields. Robustness, a term used to characterize the insensitivity of a control system to perturbations of its characteristics or parameters, is a concept that can be applied to various fields.

[0003] Currently, the technology for detecting Fano resonance mainly relies on two major platforms: optics and electromagnetics. In the optical field, photonic crystals, dielectric metasurfaces, and metallic nanostructures serve as core carriers, identifying resonance signals by detecting asymmetric peak shifts and intensity changes in the spectrum. In the electromagnetic field, metal-insulator-metal structures and electromagnetic metamaterials are used to capture changes in electromagnetic parameters during the resonance process. However, existing mainstream Fano resonance detection schemes all have limitations. Fano resonance is an asymmetric resonance phenomenon formed by the interference between discrete resonant states and continuous excited states. Unlike the Lorentz resonance, which is highly robust to the incident wave angle and polarization direction, Fano resonance in metamaterials is generated by the coupling of Fabry-Perot resonance and Lorentz resonance. The Fabry-Perot resonance is extremely sensitive to the incident angle and polarization direction, leading to unstable detection results. Summary of the Invention

[0004] This invention proposes an electromagnetic flat band for Fano resonance detection with significant robustness. Within its flat band frequency range, it can achieve robustness to Fano resonance with respect to electromagnetic incident angle and polarization.

[0005] Therefore, the technical solution adopted in this invention is: an electromagnetic flat strip for Fano resonance detection with significant robustness, wherein a plurality of first patterns and a plurality of second patterns are plated on the surface of the electrolyte substrate, and all the first patterns and all the second patterns are periodically arranged on the electrolyte substrate, the first pattern is a vertical pattern formed by rotating the second pattern by 90°, and both the first pattern and the second pattern are made of metal.

[0006] As a preferred embodiment of the above scheme, both the first pattern and the second pattern are straight lines, and the first pattern and the second pattern form a grid or linear unit array on the electrolyte substrate.

[0007] Further preferably, the first pattern and the second pattern adopt a single independent image, and two adjacent first patterns and two adjacent second patterns form a group of 2×2 rectangular patterns, and the same patterns within the rectangular patterns are arranged diagonally.

[0008] Further preferably, the first pattern adopts "H", and correspondingly, the second pattern adopts "工".

[0009] Further preferably, neither the first pattern nor the second pattern is arranged obliquely.

[0010] Further preferably, the electrolyte substrate is flexible.

[0011] Further preferably, auxiliary resonance units coupled with the patterns are arranged at the gaps between the first pattern and the second pattern on the electrolyte substrate.

[0012] Advantages of the present invention:

[0013] 1) An electrolyte substrate is used as a supporting base, and two groups of perpendicular metal structures are prepared thereon. A specific electromagnetic coupling effect is formed through the orthogonal arrangement of the metal structures, and then an optical flat band is stably generated.

[0014] 2) The formation and characteristics of the optical flat band are precisely regulated through two groups of orthogonal metal modes. Different from the designs of existing single metal modes or non-orthogonal metal structures, the present invention can generate a synergistic coupling effect between the metal structures by strictly controlling the vertical arrangement angle, size parameters, and distribution density of the two groups of metals, thereby realizing the controllable generation of the optical flat band and stably maintaining the spectral characteristics of the flat band, solving the technical pain points of difficult formation and poor stability of the existing optical flat band.

[0015] 3) By utilizing the electromagnetic characteristics around the optical flat band, the robustness of Fano resonance detection against the incident angle and polarization state of electromagnetic waves is achieved. That is, no matter how the incident angle of electromagnetic waves changes or the polarization direction is switched, the Fano resonance detection can still maintain stable detection performance, breaking the strict limitations of existing Fano resonance detection technologies on the incident angle and polarization state, expanding the applicable scenarios of Fano resonance detection, and enhancing the practicality and reliability of detection. Description of the Drawings

[0016] Figure 1 Schematic of the present invention Figure 1 (Both the first pattern and the second pattern are straight lines, forming a grid).

[0017] Figure 2 Schematic of the present invention Figure 1 (Both the first pattern and the second pattern are straight lines, forming a nanowire array).

[0018] Figure 3This is a schematic diagram of the present invention. Figure 2 (The first and second patterns are independent patterns and are not tilted.)

[0019] Figure 4 This is a schematic diagram of the present invention. Figure 3 (The first and second patterns are independent patterns and are set at an angle.)

[0020] Figure 5 for Figure 3 A schematic diagram of a set of rectangular patterns.

[0021] Figure 6 The results are simulation results for Embodiment 1 of the present invention.

[0022] Figure 7 The results are from the experiment in Embodiment 1 of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the embodiments and accompanying drawings:

[0024] like Figure 1-4 As shown, an electromagnetic flat strip for Fano resonance detection with significant robustness mainly consists of an electrolyte substrate 1, a plurality of first patterns 2 and a plurality of second patterns 3 plated on the electrolyte substrate. All first patterns 2 and all second patterns 3 are periodically arranged on the electrolyte substrate, and the first pattern 2 is a vertical pattern formed by rotating the second pattern 3 by 90°. The first pattern 2 and the second pattern 3 are both made of metal. The electrolyte substrate 1 serves as an optical substrate and can be made of materials that can be selected as needed, such as hard materials or soft materials. Among them, the soft material can be a transparent natural polymer-based gel electrolyte, such as a hydroxyethyl cellulose system.

[0025] Specifically, such as Figure 1 and Figure 2 As shown, both the first pattern 2 and the second pattern 3 are straight lines. The first pattern 2 and the second pattern 3 form a grid or nanowire array on the electrolyte substrate 1, wherein... Figure 1 The first pattern 2 and the second pattern 3 intersect to form a grid. Figure 2 The first pattern 2 and the second pattern 3 are designed to be non-intersecting, forming a linear unit array. The line width and spacing are adjusted based on the electromagnetic wave frequency detected between the two patterns.

[0026] At the same time, such as Figure 3 and 4 As shown, the first pattern 2 and the second pattern 3 can also be a single independent image, and two adjacent first patterns 2 and two adjacent second patterns 3 form a set of rectangular patterns. The same pattern is set on the diagonal within the rectangular pattern. At this time, the first pattern 2 and the second pattern 3 can not be completely orthogonal, and their orthogonal angle can be flexibly adjusted within the range of 80°-100°.

[0027] When the first pattern 2 and the second pattern 3 are single patterns, the first pattern 2 uses an "H" shape, and the second pattern 3 uses an "I" shape. Ideally, neither the first pattern 2 nor the second pattern 3 should be tilted. Figure 4 As shown.

[0028] To enhance the Fano resonance intensity, broaden the robust incident angle range, and adapt to large-angle electromagnetic wave detection scenarios, an auxiliary resonant unit coupled to the pattern can be provided on the electrolyte substrate 1 at the gap between the first pattern 2 and the second pattern 3. The auxiliary resonant unit can be made of metal nanoparticles.

[0029] Example 1: Microwave Band

[0030] An electrolyte substrate with a relative permittivity of 4.9 was selected, and the electrolyte substrate and its pattern were designed according to [reference needed]. Figure 5 The specific dimensions are set as follows: L=5mm, W=0.125mm, h=3mm, a=3mm, b=1.75mm, t=0.035mm. The first and second patterns are made of copper and are arranged in intersecting stripe patterns along the X and Y axes, respectively, forming a completely orthogonal metal pattern covering the electrolyte substrate surface. During processing, standard PCB board processing methods are used to complete the electrolyte substrate and pattern fabrication. After processing, it is ensured that there is no direct contact between different patterns and that the spacing is uniform.

[0031] First, a three-dimensional electromagnetic simulation model of the electrolyte substrate structure was established using COMSOL Multiphysics simulation software, and the corresponding simulation frequency range was set. The electromagnetic wave incident mode was perpendicular (initial angle 0°), and the polarization direction was linear polarization. The position of the optical flat band was obtained through simulation. The response characteristics of the Fano resonance around the flat band in the 0-30° incident angle range were analyzed in detail to verify the robustness within this angle range. The results are as follows: Figure 6 As shown, (a) is the transmission result of s-polarization over p-polarization at 0° oblique incidence; (b) is the transmission result of s-polarization over p-polarization at 10° oblique incidence; (c) is the transmission result of s-polarization over p-polarization at 20° oblique incidence; (d) is the transmission result of s-polarization over p-polarization at 30° oblique incidence; (e) is the transmission result of s-polarization at 0-30° oblique incidence; and (f) is the transmission result of p-polarization at 0-30° oblique incidence.

[0032] After simulation verification, a microwave far-field testing system (test angle 0-30°) and a near-field testing system were used to conduct actual measurements on the fabricated PCB samples, recording the response data of the Fano resonance under different incident angles and polarization modes. The results are as follows: Figure 7The figures show the transmission results of the s-polarization versus p-polarization at 0° oblique incidence; (b) at 10° oblique incidence; (c) at 20° oblique incidence; (d) at 30° oblique incidence; (e) at 0-30° oblique incidence; and (f) at 0-30° oblique incidence. The simulation and experimental results were confirmed to be consistent, demonstrating the robustness of Fano resonance detection to electromagnetic wave incident angles and polarizations from 0-30°.

[0033] Example 2 Terahertz Band

[0034] An electrolyte substrate adapted to the transmission characteristics of the terahertz band is selected, wherein the electrolyte substrate and its pattern are set according to... Figure 5 The dimensions are linearly scaled proportionally to the dimensions in Example 1, and the scale is the dielectric constant ratio of the electrolyte substrate. The two sets of orthogonal metal modes are made of metal materials adapted to the terahertz band and are fabricated using corresponding precision processes. The two sets of metals are arranged crosswise along the X-axis and Y-axis directions to form an orthogonal metal mode structure adapted to the terahertz band.

[0035] First, a terahertz electromagnetic simulation model of the structure was established using COMSOL Multiphysics simulation software. The simulation frequency range corresponding to the terahertz band was set, the electromagnetic wave incident mode was oblique incidence (adjustable from 0-30°), and the polarization direction was linear polarization. The optical transmission spectrum of the structure in the terahertz band was obtained through simulation, confirming the formation of a stable optical flat band. The response characteristics of the Fano resonance around the flat band under different polarization modes within the 0-30° incident angle range were analyzed to verify the robustness of the 0-30° incident angle in the terahertz band (the resonance stability decreases significantly beyond 30°). After the simulation passed, an actual sample was prepared, and a terahertz far-field testing system (test angle 0-30°) was used. The incident angle and polarization mode were adjusted to test the detection performance of the Fano resonance under different conditions. At the same time, a terahertz near-field scanning microscope was used to test the near-field electromagnetic distribution around the flat band. Finally, by comparing simulation and experimental data, it was confirmed that the orthogonal metallic mode structure can stably form an optical flat band in the terahertz band and can achieve good robustness of Fano resonance detection to electromagnetic wave incident angles and polarizations of 0-30°, making it suitable for weak signal detection scenarios in the terahertz band.

[0036] Example 3: Near-infrared band

[0037] An electrolyte substrate with good near-infrared transmittance and low loss is selected, wherein the electrolyte substrate and pattern are designed according to... Figure 5The dimensions are linearly scaled proportionally to the dimensions in Example 1, and the scale is the dielectric constant ratio of the electrolyte substrate. The two sets of orthogonal metal modes are made of metal materials adapted to the near-infrared band and are prepared using corresponding precision processes. The two sets of metals are arranged along the X-axis and Y-axis directions to form an orthogonal array mode, which is completely orthogonal and corresponding in position, forming an orthogonal metal array structure adapted to the near-infrared band.

[0038] First, an electromagnetic simulation model for the near-infrared band was established using COMSOL Multiphysics simulation software. The simulation wavelength (frequency) range corresponding to the near-infrared band was set, with the electromagnetic wave incident vertically and the polarization direction linear. The simulation obtained the wavelength (frequency) corresponding to the optical flat band. The focus was on analyzing the response stability of the Fano resonance around the flat band under different polarization modes within the 0-30° incident angle range, verifying the robustness of the 0-30° incident angle in the near-infrared band. After simulation verification, actual samples were prepared, and the absorption and reflection spectra of the Fano resonance under different incident angles and polarization modes were tested using a near-infrared far-field testing system (test angle 0-30°). At the same time, the near-field electromagnetic enhancement effect on the sample surface was tested using a near-field optical microscope. Finally, the position of the flat band and the peak value of the Fano resonance were compared with those of the simulation and actual measurements, confirming that the orthogonal metal array structure can stably form an optical flat band in the near-infrared band, achieving good robustness of Fano resonance detection to electromagnetic wave incident angles and polarizations within the 0-30° range, making it suitable for near-infrared biosensing, optical detection, and other scenarios.

Claims

1. An electromagnetic flat band for Fano resonance detection with significant robustness, characterized in that: It includes an electrolyte substrate (1), on the surface of which several first patterns (2) and several second patterns (3) are plated, and all the first patterns (2) and all the second patterns (3) are arranged periodically on the electrolyte substrate. The first pattern (2) is a vertical pattern formed by rotating the second pattern (3) by 90°, and the materials of the first pattern (2) and the second pattern (3) are both metals.

2. The electromagnetic flat band for Fano resonance detection with significant robustness as described in claim 1, characterized in that: Both the first pattern (2) and the second pattern (3) are straight lines, and the first pattern (2) and the second pattern (3) form a grid or a linear unit array on the electrolyte substrate (1).

3. The electromagnetic flat band for Fano resonance detection with significant robustness as described in claim 1, characterized in that: The first pattern (2) and the second pattern (3) are single independent images, and two adjacent first patterns (2) and two adjacent second patterns (3) form a 2×2 rectangular pattern, and the same patterns within the rectangular pattern are arranged on the diagonals.

4. The electromagnetic flat band for Fano resonance detection with significant robustness as described in claim 3, characterized in that: The first pattern (2) is "H", and correspondingly, the second pattern (3) is "工".

5. The electromagnetic flat band for Fano resonance detection with significant robustness as described in claim 3, characterized in that: Neither the first pattern (2) nor the second pattern (3) is inclined.

6. The electromagnetic flat band for Fano resonance detection with significant robustness as described in claim 1, characterized in that: The electrolyte substrate (1) is flexible.

7. The electromagnetic flat band for Fano resonance detection with significant robustness as described in claim 1, characterized in that: Auxiliary resonance units coupled with the patterns are provided at the gaps between the first pattern (2) and the second pattern (3) on the electrolyte substrate (1).

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