Intermediate infrared strong coupling metasurface platform based on self-hybridization molecular structure

Abstract

The invention discloses an intermediate infrared strong coupling metasurface platform based on a self-hybridization molecular structure. The platform comprises: a substrate; the substrate has asymmetry, and the refractive index is greater than or equal to 1.4; infrared active molecular structures are periodically arranged on the surface of the substrate, and the period range is 100-7000 nm; each infrared active molecule structure comprises two groups of infrared active molecule units of rod-shaped units; the two groups of infrared active molecule units are parallel to each other and have overlapped symmetric axes; and the size difference of the two groups of infrared active molecule units in the length direction is 150-2100 nm. According to the platform, mid-infrared quasi-continuous and bound modes are induced through structural design, so that molecules serve as oscillators and resonant cavities, and self-matching in space and frequency is achieved. And finally, strong light-molecular vibration coupling is realized in a middle-infrared band, and high Q factor, high sensitivity, wide material adaptability and structural adjustability are shown.

Description

Technical Field

[0001] This invention relates to the intersection of mid-infrared nano-optics and molecular spectroscopy, and in particular to a novel platform device that combines the interaction of molecular vibrational modes and optical resonant modes. This device can be applied to biochemical sensing, molecular recognition, and polaron chemical manipulation, achieving sensitive and tunable molecular detection and energy level manipulation in the mid-infrared band. Background Technology

[0002] Mid-infrared spectroscopy can reveal information about chemical bonds within molecules, making it an important tool for non-destructive, fingerprint-like molecular identification. However, traditional mid-infrared sensors are limited in detection sensitivity, making it difficult to achieve single-molecule-level infrared absorption identification. Surface-enhanced infrared absorption (SEIRA) technology utilizes a localized electric field to enhance the infrared signal, improving sensitivity, but it generally suffers from the following drawbacks:

[0003] Relying on metallic plasmon structures results in significant losses and low quality factors (Q-factors). Rapid decay of the local electric field leads to a rapid decrease in coupling efficiency when the molecular layer thickness exceeds a critical value. Furthermore, the complex integration of distorted interfaces and heterogeneous structures introduces energy losses and creates fabrication bottlenecks. While current high-quality factor structures based on photonic crystals and optical cavities offer advantages in low loss, their typically large mode sizes limit strong coupling and are detrimental to high-sensitivity molecular detection. Summary of the Invention

[0004] In view of this, the purpose of this invention is to propose a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure. This platform induces mid-infrared quasi-continuous-domain bound states (q-BIC) modes through structural design, enabling the molecule itself to act as both an oscillator and a resonant cavity, achieving spatial and frequency self-matching. Ultimately, it achieves strong light-molecular vibrational coupling in the mid-infrared band, exhibiting high Q-factor, high sensitivity, wide material adaptability, and structural tunability.

[0005] According to one aspect of the present invention, a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure is provided, comprising:

[0006] A substrate; the substrate has asymmetry and a refractive index ≥ 1.4; and,

[0007] The substrate surface has periodically arranged infrared active molecular structures with a periodic range of 100 nm to 7000 nm. Each infrared active molecular structure contains two sets of rod-shaped infrared active molecular units. The two sets of infrared active molecular units are parallel to each other and their symmetry axes coincide. The length difference between the two sets of infrared active molecular units is 150 nm to 2100 nm.

[0008] The core of the above technical solution lies in directly constructing infrared-active molecular materials into periodic resonant structural units with a self-coupling mechanism of optical resonance and molecular vibration (i.e., "self-hybridized molecular structures"), forming metasurfaces. This design aims to simultaneously overcome the shortcomings of traditional surface-enhanced infrared absorption (SEIRA) technology, such as high loss, low Q factor, fast field decay, and complex fabrication, as well as the limitation of large volume of high-Q photonic crystal / optical cavity modes, providing a new approach to achieve high-sensitivity, strongly coupled molecular detection in the mid-infrared band.

[0009] Infrared-active molecules themselves are fabricated into resonant units with specific morphologies (two sets of symmetrical units with a size difference of 150-2100 nm) through micro-nano fabrication, rather than being attached to a metal structure as an external molecular layer in traditional SEIRA. Within each unit, the two sets of symmetrical structures with different sizes exhibit detuning of their intrinsic resonant frequencies. When they are close together, they form a hybrid mode through near-field coupling (similar to the principle of electromagnetically induced transparent EIT or Fano resonance). This hybrid mode generates a narrow-linewidth resonance with an extremely high Q factor and a highly localized strong electric field hotspot (usually located in the gap region formed by the size difference). This invention utilizes molecular materials (whose loss in a specific mid-infrared band may be lower than that of metals) to construct the structure and significantly suppresses radiation loss through hybrid modes (especially "dark modes"), achieving high Q resonance and enhancing coupling strength. In traditional SEIRA substrates, the local field attenuates rapidly on the metal surface, and the coupling efficiency drops sharply when the molecular layer is too thick. In this invention, the strong electric field hotspot is directly generated within or on the surface of the resonant structure composed of infrared-active molecules (such as in the size difference region). The analyte adsorbs in this hotspot region, highly overlapping with the localized enhanced field space, resulting in high coupling efficiency and significantly reduced sensitivity to molecular layer thickness. Traditional SEIRA requires the integration of molecular layers on metal nanostructures, leading to issues such as distorted interfaces, poor contact, and complex fabrication. In this case, the resonant structure itself is an infrared-active molecular material, eliminating the need for additional heterogeneous molecular layers. The entire platform (substrate + periodic molecular structure) can be fabricated using standardized micro / nano fabrication methods (such as photolithography, etching, and nanoimprinting), avoiding losses and fabrication bottlenecks caused by heterogeneous interfaces. The subwavelength unit structure (period 5100-7000 nm) and the hybridization modes within the unit (especially the interstitial hotspots) in this case highly localize the light field energy at the nanoscale, achieving an extremely small optical mode volume. The combination of a high Q-factor and a small mode volume greatly enhances the intensity of the interaction between the light field and matter (including the structure's own molecules and the analyte molecule), creating ideal conditions for strong coupling (polaritons) between the analyte molecule and the optical mode. This forms the theoretical basis for achieving sensitive detection at the single-molecule level.

[0010] Specific infrared-active molecular materials are directly fabricated into rod-shaped micro / nano resonant structure units with internal size-mistuned coupling, and periodically arranged to form metasurfaces. The core of this approach lies in achieving "material as structure" and "structure self-hybridization." By inducing mode hybridization through size differences in the symmetrical substructures within the unit, the bottlenecks of traditional SEIRA technology (high loss, low Q, fast field decay, complex fabrication) and high-Q photonic structures (large mode volume) are simultaneously overcome. The "self-hybridization" unit morphology consists of two parallel, symmetrical nanorods with a length difference of 150-2100 nm. The size difference leads to longitudinal / lateral resonant mistuning, coupling to form high-Q hybrid modes.

[0011] Regardless of the specific morphology, the intrinsic resonance frequencies of the two sets of symmetrical substructures with size differences within the unit cell are detuned. Under near-field coupling, an EIT / Fano-like hybrid mode is generated, forming narrow-linewidth (high Q-factor) resonances and nanoscale strong electric field hotspots localized in the size difference region (bar gap). The strong electric field is directly localized in the key region (bar gap) of the molecular material structure itself. The hotspot size matches the unit cell nanoscale (150-2100 nm difference region). The analyte molecule is adsorbed on the structural surface, either naturally embedded or adjacent to the hotspot, maximizing the coupling efficiency. This completely avoids the molecular layer thickness limitation (monolayer requirement) caused by the short-range evanescent field in metallic SEIRAs, significantly reducing thickness sensitivity. The rod shape is beneficial for studying linear molecular / bond orientations.

[0012] In some embodiments, the infrared active molecules include CBP materials, PMMA materials, polystyrene, polymethyl methacrylate derivatives, and protein films.

[0013] In the above technical solutions, the platform directly uses molecular materials with mid-infrared characteristic absorption to construct resonant units, including: organic semiconductor / phosphorescent host materials such as CBP (4,4'-bis(N-carbazole)-1,1'-biphenyl), whose molecular vibrational modes have absorption in specific mid-infrared bands; classic polymers such as PMMA (polymethyl methacrylate) and polystyrene (PS), whose stretching and bending vibrations of CH, C=O, etc., provide rich mid-infrared fingerprint spectra; polymer derivatives such as polymethyl methacrylate derivatives can have their infrared absorption characteristics, refractive index, and processing properties adjusted through chemical modification; and biomolecular materials such as the amide I band of protein films (C=O stretching, ~1650 cm⁻¹). -1 / 6.06μm), amide II band (NH bending / CN stretching, ~1550cm) -1The 6.45 μm region is an important infrared fingerprint region for biomolecules. Each unit cell consists of two sets of symmetrical structures (such as nanorods and nanoblocks) with different sizes. This size difference leads to detuning of the resonant frequencies of the two substructures within the unit cell, forming hybrid modes (such as EIT / Fano-like resonances) under near-field coupling, resulting in high Q-factor, narrow linewidth resonances and strong localized field hotspots at the nanoscale (concentrated in the region of size difference). The selected molecular materials (especially PMMA, PS and their derivatives, and proteins) generally exhibit lower intrinsic optical losses than metals in specific mid-infrared bands (such as fingerprint regions), laying the foundation for high Q. The selected materials (especially PMMA, PS, and PMMA derivatives) are mature micro / nanofabrication materials (such as photoresists and nanoimprint lithography), and CBP is also commonly used in vacuum evaporation or solution processing of organic electronic devices. Protein films can be formed through spin coating, Langmuir-Blodgett, and other methods. The entire metasurface (substrate + periodic molecular structure) can be fabricated using processes such as photolithography / electron beam lithography combined with etching (RIE), nanoimprinting, or thin film deposition and patterning.

[0014] In some embodiments, the periodicity of the infrared active molecule structure ranges from 5100 nm to 7000 nm; the width of the infrared active molecule unit bar ranges from 1500 nm to 2100 nm, the bar height ranges from 400 nm to 800 nm, and the bar length ranges from 3900 nm to 5500 nm.

[0015] In the above technical solution, infrared-active molecular materials are processed into high aspect ratio nanorod units. The size difference between the two sets of symmetrical structures is a reduction in the length of the rods; the range is 1500nm–2100nm wide, 400nm–800nm ​​high, and 3900nm–5500nm long, arranged periodically (period 5100nm–7000nm). The size difference (150nm–2100nm) between the symmetrical double rods induces a self-hybridization effect, achieving synergistic optimization of high Q-factor, nanoscale localized field, and small mode volume. The core physical significance of the structural parameters lies in:

[0016]

[0017]

[0018] In some embodiments, the length of the infrared active molecular unit is 2.66 times the width of the rod, and the period of the infrared active molecular structure is 3.4 times the width of the rod.

[0019] The optimized version of the above technical solution has a narrower linewidth, a higher Q factor, higher sensitivity, and a higher local electric field strength.

[0020] According to another aspect of the present invention, a method for preparing a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure is provided, the method comprising:

[0021] Using a material with asymmetry and a refractive index ≥1.4 as a substrate, photoresist micro-nano arrays were fabricated by spin-coating photoresist and then using an etching method.

[0022] Using the fabricated photoresist micro-nano array as a hard mask, an infrared active molecular film of a given thickness is thermally evaporated on its surface.

[0023] The photoresist is swollen and peeled off, leaving only an infrared-active molecular micro-nano array that complements the pattern.

[0024] In the above technical solution, using a photoresist micro / nano array as a hard mask, combined with thermal evaporation technology, enables the high-resolution and high-precision fabrication of infrared active molecule micro / nano arrays, meeting the stringent requirements of mid-infrared strongly coupled metasurface platforms for the size and shape of micro / nano structures. By swelling and stripping the photoresist, the pattern of the photoresist micro / nano array can be effectively transferred onto the infrared active molecule film, resulting in an infrared active molecule micro / nano array that is highly complementary to the photoresist pattern, ensuring the structural integrity of the metasurface platform.

[0025] Unlike SEIRA technology, which relies on metallic plasmon structures, this method selects materials with asymmetry and high refractive index as substrates and utilizes infrared-active molecular micro / nano arrays to modulate mid-infrared light. This avoids the significant losses associated with metallic plasmon structures, thus improving the quality factor (Q-factor) of the metasurface platform and enhancing its infrared signal detection capabilities. Because this fabrication method allows precise control over the shape and size of the infrared-active molecular micro / nano arrays, the infrared-active molecules can form a relatively stable and uniformly distributed local electromagnetic field in a specific region. Unlike the rapid decay of the local electric field in SEIRA technology, the metasurface platform fabricated by this method maintains a high intensity of the local electric field within a certain range with slower decay, providing a more persistent and effective electric field enhancement for molecules. This improves the excitation and detection efficiency of molecular vibrational modes and allows for better adaptation to molecular layers of varying thicknesses, broadening the applicability of the metasurface platform. Compared with traditional methods for preparing high-quality factor structures, this method uses only photoresist micro / nano arrays as hard masks, combined with conventional processes such as thermal evaporation and swelling stripping. This avoids the complex integration of heterogeneous structures and the generation of deformed interfaces, reduces energy loss during the preparation process, simplifies the preparation process, and improves the feasibility and reliability of the preparation. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of an embodiment of a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure according to the present invention.

[0028] Figure 2 This is a schematic diagram of the transmission spectrum of a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure according to an embodiment of the present invention, under the condition that other size parameters are the same, with ΔL0 in the range of 0nm to 1950nm without molecular absorption.

[0029] Figure 3 This is a schematic diagram of the transmission spectrum (bar width range w = 1880 nm ~ 2020 nm) of a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure according to an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of the local electric field enhancement of CBP molecular structure in an embodiment of a mid-infrared strongly coupled metasurface platform based on self-hybridized molecular structure according to the present invention.

[0031] Figure 5 This is a schematic diagram of the CBP dielectric constant of an embodiment of a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure according to the present invention; wherein, the left figure is the real part of the CBP dielectric constant and the right figure is the imaginary part of the CBP dielectric constant.

[0032] Figure 6 This is a schematic diagram of the transmission spectrum of a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure according to an embodiment of the present invention, under the condition that other size parameters are the same, with no molecular absorption in the range of h from 400-800 nm.

[0033] Figure 7 This is a schematic diagram of the transmission spectrum of CBP molecular self-hybrid coupling (bar width range w = 1880 nm ~ 2020 nm) according to an embodiment of a mid-infrared strongly coupled metasurface platform based on self-hybridized molecular structure of the present invention.

[0034] Figure 8 This is a schematic diagram of the transmission spectrum (bar width range w = 1580 nm ~ 1720 nm) of a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure according to an embodiment of the present invention.

[0035] Figure 9This is a schematic diagram of the transmission spectrum of PMMA molecules with self-hybridized coupling (rod width range w = 1580 nm ~ 1720 nm) according to an embodiment of a mid-infrared strongly coupled metasurface platform based on self-hybridized molecular structure of the present invention.

[0036] Figure 10 This is a schematic diagram of the transmission spectrum of a protein molecule self-hybrid coupling (rod width range w = 1620 nm to 1960 nm) according to an embodiment of a mid-infrared strongly coupled metasurface platform based on self-hybridized molecular structure of the present invention. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1

[0039] Structural Design and q-BIC Mode Excitation

[0040] Principle: This embodiment is based on the symmetry-broken excitation of quasi-continuous domain bound state (q-BIC) resonance modes, by introducing a CBP double-bar array structure of unequal lengths ( Figure 1 The diagram shows the structure (1 is the substrate, and 2 and 3 are CBP double rod array structures of different lengths) to excite the q-BIC mode and achieve an ultra-high Q factor mid-infrared resonance response.

[0041] Implementation Method: A periodic structure with a periodicity of 6630 nm is constructed on a substrate using CBP material. (Note that: First, the substrate material must have a high refractive index in the mid-infrared band. In air (refractive index 1), the refractive index of the substrate material must be greater than or equal to 1.4. Second, the substrate material must have strong molecular vibrational absorption and low loss in the mid-infrared band. Third, the substrate structure must have asymmetry to excite quasi-continuous bound state (q-BIC) resonance modes. Finally, the length, width, height, and period of the rod-shaped structure in the substrate structure must meet certain ranges so that its q-BIC resonance wavelength is located in the mid-infrared band.) Figure 1 A unit consisting of two asymmetric rod-like structures. The length and width of this unit constitute the period of the structure; it can also be understood as the distance from the midpoint of one rod to the midpoint of the other rod in the adjacent unit. The rod is 1950 nm wide, 600 nm high, and 5187 nm long. Figure 1For example, the long rod needs to be centered horizontally and centered vertically at the upper half of P / 2; the short rod has a similar position. The rod length and period must simultaneously satisfy the relationship with the rod width. Symmetry breaking is achieved by controlling the length difference ΔL0 between the two rods within the range of 195nm to 1950nm. The transmission spectrum and local electric field distribution are calculated using the finite element method numerical simulation.

[0042] Implementation Results: This structure achieves symmetry breaking through the length difference ΔL0, resulting in a quasi-continuous bound state (q-BIC) resonance peak. Figure 2 The transmission spectrum without molecular absorption (length difference ΔL0 = 0 nm ~ 1950 nm) should be noted. Figure 2 To disregard vibrational absorption by molecular materials, the transmission spectra of metasurfaces with different structural sizes are shown, where each line corresponds to the width of the actual length difference (ΔL0) between the two rods (in nm), and the distance is 1450 cm⁻¹. -1 High Q-factor resonance is achieved nearby ( Figure 3 The transmission spectrum without molecular absorption (bar width range W = 1880 nm ~ 2020 nm) is noteworthy. Figure 3 To disregard vibrational absorption of molecular materials, the transmission spectra of metasurfaces with different structural sizes were obtained by tuning the q-BIC resonance position to near the resonance position of the CBP molecule (each line corresponds to the actual rod width in nm). The electric field is mainly localized in the internal region of the rod, with a local electric field enhancement factor exceeding 10 times. Figure 4 (Local electric field enhancement diagram), laying the foundation for subsequent strong coupling.

[0043] Example 2

[0044] Self-hybridization coupling and Rabi splitting

[0045] Principle: This structure achieves spatial frequency overlap between the molecular vibrational modes and the structural resonance modes, spontaneously forming a photo-molecular hybrid state. Under strong coupling conditions, the original vibrational absorption peak will split into upper and lower polariton branches, producing typical Rabi splitting.

[0046] Implementation method: Based on the structure of Example 1, the dispersive dielectric constant of actual CBP material (containing three vibrational peaks: 1450 cm⁻¹) is adopted. -1 1478cm -1 1504cm -1 ()( Figure 5 (CBP dielectric constant), and tuned the structural resonance to 1450 cm⁻¹. -1Vibrational mode resonance. Structural parameters were set as follows: ΔL0 = 780 nm, h = 600 nm, P = 6630 nm. The transmission spectrum of the structure was characterized by tuning the resonant frequency by changing the rod width (W). Furthermore, the relationship between the rod height and the resonance position of the quasi-continuous bound state (q-BIC) was determined by changing the rod height (400 nm–800 nm) while keeping other parameters constant. Figure 6 The transmission spectrum without molecular absorption (bar height (h) range = 400 nm to 800 nm) should be noted. Figure 6 (This refers to the transmission spectra of metasurfaces of different thicknesses under the same size parameters, without considering the vibrational absorption of molecular materials).

[0047] Implementation effect: When the resonant frequency is 1450cm -1 When the peaks overlap, a distinct Rabi splitting phenomenon appears in the transmission spectrum, with the peaks splitting at 39.5 cm⁻¹. -1 The corresponding coupling strength is g = 20.5 cm. -1 ( Figure 7 The transmission spectrum of CBP molecules through self-hybridization coupling is noteworthy. Figure 7 To consider the CBP molecule at 1450 cm⁻¹ -1 The q-BIC resonance position was tuned to near the resonance position of the CBP molecule, and each line corresponds to the actual rod width (in nm). The dispersion curves exhibit typical anti-crossover characteristics, confirming that the system is in a strongly coupled region.

[0048] Example 3

[0049] Principle: In addition to CBP, many infrared-active materials also possess tunable vibrational peaks. This platform, as a general-purpose self-coupled photonic structure, can be used to construct multi-material, multi-frequency coupled systems.

[0050] Implementation method: Replace CBP with poly(methyl methacrylate, PMMA) material, and use the Lorentz dispersion model (background dielectric constant ε). ∞ =2.2, resonant frequency ω0=3.252×10 14 rad / s, intensity factor f0 = 0.016, damping Γ = 3.41 × 10 12 (rad / s). Keeping the structural geometry constant, the bar width (W) was changed to adjust the q-BIC mold to 1700 cm. -1 Nearby, high Q-factor resonance is achieved ( Figure 8The transmission spectrum without molecular absorption (bar width range W = 1580-1720 nm) should be noted. It should be noted that since the refractive index and mid-infrared vibrational peak position of PMMA molecules are different from those of CBP, different width ranges are required to adjust the resonance peak position of the q-BIC structure of PMMA molecules to be near the mid-infrared vibrational peak position of PMMA molecules.

[0051] Implementation Results: Simulation results show that, under the condition that the q-BIC mode coincides with the PMMA vibrational peak, the splitting of upper and lower polarons also occurs, and the anti-crossing characteristics are clear. Figure 9 The transmission spectrum of PMMA molecules through self-hybridization coupling is noteworthy. Figure 9 To consider the PMMA molecule at 1740 cm⁻¹ -1 The vibrational absorption of PMMA molecules was used to tune the q-BIC resonance position to near the vibrational absorption position of PMMA molecules. Each line corresponds to the actual rod width (in nm). This verifies the universality and reconfiguration capability of this platform in multi-material systems.

[0052] Example 4

[0053] Implementation method: Replace CBP or PMMA with protein materials, and use the Lorentz dispersion model (background dielectric constant ε) for actual protein materials. ∞ =2.08, resonant frequency ω1 = 1668cm -1 ω2=1532cm -1 Intensity factor f1 = 312 cm -1 f2 = 200cm -1 Damping Γ1 = 78.1 cm -1 Γ2=101cm -1 Keeping the structural geometric proportions constant, the bar width (W) was changed to adjust the q-BIC mold to 1532 cm. -1 1668cm -1 Nearby, a high Q-factor resonance is achieved.

[0054] Implementation Results: Simulation results show that, under the condition that the q-BIC mode coincides with the protein vibrational peak, the splitting of upper and lower polarons and the anti-crossing characteristic also occur. Figure 10 The transmission spectrum of protein molecule self-hybridization coupling further verifies the universality and reconfiguration capability of this platform in multi-material systems.

[0055] Example 5

[0056] The preparation methods of one to four of the above embodiments are as follows (taking CBP as an example):

[0057] Using silicon wafers or glass as substrates, the substrates are first cleaned and dried with oxygen plasma, then a certain thickness of PMMA photoresist is spin-coated and pre-baked to remove the solvent. Subsequently, electron beam lithography is used to expose the substrate according to the design pattern. After that, the substrate is developed and fixed in a developer solution and then dried with nitrogen.

[0058] Using the fabricated PMMA micro / nano array as a "hard mask", a CBP film of a given thickness is first thermally evaporated on its surface. Then, the entire structure is immersed in acetone for 5 to 10 minutes. The PMMA is swollen and peeled off, and the CBP on it falls off, leaving only the CBP micro / nano array that is complementary to the PMMA pattern on the substrate.

[0059] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification and drawings, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure, characterized in that, include: A substrate; The substrate has asymmetry and a refractive index ≥1.4; as well as, The substrate surface has periodically arranged infrared active molecular structures with a periodic range of 100 nm to 7000 nm. Each infrared active molecular structure contains two sets of rod-shaped infrared active molecular units. The two sets of infrared active molecular units are parallel to each other and their symmetry axes coincide. The length difference between the two sets of infrared active molecular units is 150 nm to 2100 nm.

2. The mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure as described in claim 1, characterized in that, The infrared active molecules include CBP materials, PMMA materials, polystyrene, polymethyl methacrylate derivatives, and protein films.

3. The mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure as described in claim 1, characterized in that, The periodic range of the infrared active molecule structure is 5100nm to 7000nm; the width range of the infrared active molecule unit bar is 1500nm to 2100nm, the bar height range is 400nm to 800nm, and the bar length range is 3900nm to 5500nm.

4. A mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure as described in claim 1 or 3, characterized in that, The length of the infrared active molecular unit is 2.66 times the width of the rod, and the period of the infrared active molecular structure is 3.4 times the width of the rod.

5. A method for preparing a mid-infrared strongly coupled metasurface platform based on a self-hybridized molecular structure, characterized in that, The method includes: Using a material with asymmetry and a refractive index ≥1.4 as a substrate, spin-coated photoresist is exposed according to the designed pattern using electron beam lithography. After exposure, it is developed, fixed and dried to obtain a photoresist micro-nano array. Using the fabricated photoresist micro-nano array as a hard mask, an infrared active molecular film of a given thickness is thermally evaporated on its surface. The photoresist is swollen and peeled off, leaving only an infrared-active molecular micro-nano array that complements the pattern.

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