A multimode optical resonant cavity composite plasmon surface and its preparation method

Abstract

This invention relates to a multi-mode optical resonant cavity composite plasmon surface and its fabrication method. The structure comprises a substrate (1), a metal layer (2) placed on the substrate, a polymer film (3) spin-coated on the metal layer (2), a photoresist (4) spin-coated on the polymer film (3), a two-dimensional nanoarray (5) constructed on the photoresist (4) using nanoimprinting technology, and a one-dimensional multilayer film (6) deposited on the surface of the two-dimensional nanoarray (5). This invention combines the Fabry-Perot (F-P) cavity mode of the one-dimensional multilayer film, the periodic lattice resonance mode and the dielectric cavity mode of the two-dimensional nanoarray, and the plasmon effect of the metal surface, exhibiting multiple resonance modes in the visible light band. The resonant absorption of the two-dimensional nanoarray is significantly enhanced, and its absorption bandwidth is also broadened. This invention has strong spectral modulation capabilities and a simple fabrication method.

Description

Technical Field

[0001] This invention relates to the field of spectral modulation, and mainly to a multimode optical resonant cavity composite plasmon surface and its preparation method. Background Technology

[0002] Spectral modulation has important applications in sensing, detection, and catalysis, especially in the visible light band, which can be used for optical camouflage, color printing, and thermophotovoltaic devices. Therefore, visible light spectral modulation has attracted widespread attention from academia and industry. Designing and fabricating corresponding spectral modulation structures according to practical needs has significant research value and practical application.

[0003] With the development of micro- and nano-fabrication technology, the fabrication of structures at the micrometer and nanometer scale has become possible. Micro- and nano-structures, due to their flexible design, provide an effective means for spectral manipulation. Researchers have designed a variety of visible light-modulated structures. For example, Battulga Munkhbat et al. designed a multilayer film with a Fabry-Perot (FP) cavity effect, which maintains an absorption intensity of over 50% in the visible light band [ACS Photonics, 2019, 6(1), 139–147]; Namkyu Lee et al. designed a metal-dielectric-metal plasmon structure with a specific top layer shape to achieve efficient absorption at the resonance wavelength [ACS Applied Materials Interfaces 2019, 11, 21250-21257]. Jinwu Dong et al. constructed a TiO2 array on a gold substrate, excited the surface lattice resonance mode in the visible light band, and formed a sharp absorption peak, which is sensitive to changes in the surrounding environment [Advanced Optical Materials, 2020, 2000877].

[0004] However, the effect of a single resonance mode on spectral modulation is limited. The absorption performance of the FP cavity is often limited by the film thickness parameter, which is not conducive to broadband or multi-band spectral modulation. Although plasmon resonance structures can achieve strong localization of the optical field, they also introduce ohmic losses. Surface lattice resonances rely on the coupling between structures and have a weak effect on the localization of the optical field. Combining different resonance modes to modulate the spectrum can not only make full use of the advantages of each mode, but also provide a solution for achieving multi-band, broadband absorption and strong optical field localization. At present, structures with two or three optical resonance modes have been studied. For example, Raghwendra Kumar et al. simulated a multilayer film composite disk array structure, which excited the FP cavity and plasmon mode in the infrared band, forming 1-2 absorption peaks with absorption intensities higher than 0.8 [Journal of Nanophotonics, 2020, 14(1), 016011]. However, the more resonance modes a microstructure has, the more complex the design becomes, increasing the difficulty of fabrication. Therefore, considering factors such as structural performance and ease of fabrication, it is essential to design a spectral control structure that can flexibly control visible light properties, has a simple fabrication method, and is compatible with conventional micro-nano processes. Summary of the Invention

[0005] To enhance the interaction between light and matter, achieve broadband absorption and strong light field localization, and overcome the problems of complex micro-nano structure size and high design and fabrication difficulty, this invention combines a multilayer film with FP cavity effect and a two-dimensional nanoarray with periodic lattice resonance mode, dielectric cavity mode and plasmon effect to provide a multimode optical resonant cavity composite plasmon surface, which enables flexible control of visible light.

[0006] To achieve the above objectives, the structure provided by the present invention includes a substrate 1, a metal layer 2 placed on the substrate, a polymer film 3 spin-coated on the metal layer 2, a photoresist 4 spin-coated on the polymer film 3, a two-dimensional nanoarray 5 constructed on the photoresist 4 by nanoimprinting technology, and a one-dimensional multilayer film 6 deposited on the surface of the two-dimensional nanoarray 5.

[0007] For substrate 1, its main function is to support the composite structure, and it can be either a silicon wafer or a glass sheet.

[0008] First, a metal layer 2 with high reflectivity in the visible light band is deposited on the substrate 1. Gold, silver, aluminum or copper can be selected, and the thickness is 40-100nm. This can effectively suppress the transmission of visible light.

[0009] The polymer film 3 spin-coated onto the metal layer 2 is polymethyl methacrylate or polycarbonate; its thickness is 40-150 nm.

[0010] The photoresist 4 spin-coated on the polymer film 3 is a UV-curable adhesive; its thickness is 150-250 nm.

[0011] Preferably, the two-dimensional nanoarray 5 structural unit is a cylinder; the diameter of the two-dimensional nanoarray 5 structural unit is 200-350nm, the height is 200-400nm, and the array period is 550-650nm.

[0012] Preferably, the one-dimensional multilayer film 6 is formed by sequentially stacking a metal layer, a dielectric layer, and another metal layer. Preferably, the metal material of the metal layer is gold, silver, aluminum, or copper, and the dielectric material of the dielectric layer is magnesium fluoride, zinc selenide, zinc sulfide, or magnesium sulfide.

[0013] Preferably, the thicknesses of the one-dimensional multilayer film 6 from bottom to top are 20-35nm, 30-120nm, and 10-20nm respectively.

[0014] The visible light modulation structure designed in this invention is prepared by means of the following steps:

[0015] (1) Cleaning of substrate 1: Place substrate 1 in an ethanol solution for ultrasonic cleaning, then clean it with deionized water, blow it dry with nitrogen, and dry it on a hot plate.

[0016] (2) Depositing metal layer 2: Depositing metal layer 2 on the substrate using electron beam evaporation or resistance evaporation techniques;

[0017] (3) Coating polymer film 3: Use a spin coater to uniformly coat polymer film 3 onto metal layer 2;

[0018] (4) Coating photoresist 4: Use a spin coater to uniformly coat the polymer film 3 with photoresist 4;

[0019] (5) Constructing a two-dimensional nanoarray 5: The pattern on the photomask is transferred onto the photoresist 4 by nanoimprinting technology;

[0020] (6) Deposition of one-dimensional multilayer film 6: A one-dimensional multilayer film 6 consisting of a metal layer, a dielectric layer, and a metal layer is sequentially deposited on the above two-dimensional nanoarray 5 using electron beam evaporation or resistance evaporation technology.

[0021] Beneficial effects: (1) This invention provides a multimode optical resonant cavity composite plasmonic surface and its preparation method, which combines the Fabry-Perot (FP) cavity mode of a one-dimensional multilayer film, the periodic lattice resonance mode of a two-dimensional nanoarray, the dielectric cavity mode and the plasmonic effect of a metal surface, and can exhibit multiple resonance modes in the visible light band, significantly enhancing the local effect on the incident light field, which is far superior to the enhancement effect of using a one-dimensional multilayer film or a two-dimensional nanoarray alone; (2) The multimode optical resonant cavity composite plasmonic surface and its preparation method provided by this invention can adjust the process parameters of the one-dimensional multilayer film according to different needs of actual applications, so that the multimode resonance absorption characteristics are continuously adjustable in the visible light band; (3) This invention has the advantages of simple structure and short preparation time. Attached Figure Description

[0022] Figure 1 This is a cross-sectional schematic diagram of the surface of the multimode optical resonator composite plasmon resonance of the present invention.

[0023] Figure 2 This is a SEM image of the surface of the multimode optical resonant cavity composite plasmon in Embodiment 1 of the present invention.

[0024] Figure 3 The reflection spectrum of the two-dimensional nanoarray prepared by nanoimprint technology in Example 1 of this invention is shown in the 300-800nm ​​range.

[0025] Figure 4 a represents the 300-800 nm reflectance spectrum of the one-dimensional multilayer film in Embodiment 1 of the present invention. Figure 4 b represents the 300-800 nm reflection spectrum of the multimode optical resonant cavity composite plasmon surface in Example 1.

[0026] Figure 5 a represents the 300-800nm ​​reflectance spectrum of the one-dimensional multilayer film in Embodiment 2 of the present invention. Figure 5 b represents the 300-800 nm reflection spectrum of the composite plasmon surface of the multimode optical resonator in Example 2.

[0027] Figure 6 a represents the 300-800nm ​​reflectance spectrum of the one-dimensional multilayer film in Embodiment 3 of the present invention. Figure 6 b represents the 300-800 nm reflection spectrum of the multimode optical resonant cavity composite plasmon surface in Example 3. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments:

[0029] like Figure 1As shown, the present invention designs a multimode optical resonant cavity composite plasmon surface, including a substrate 1, a metal layer 2 placed on the substrate, a polymer film 3 spin-coated on the metal layer, a photoresist 4 spin-coated on the polymer film, a two-dimensional nanoarray 5 constructed on the photoresist by nanoimprinting technology, and a one-dimensional multilayer film 6 deposited on the surface of the two-dimensional nanoarray.

[0030] Example 1:

[0031] The fabrication process of the multimode optical resonator composite plasmon surface in this embodiment is as follows:

[0032] (1) Cleaning of substrate 1: Select polished glass sheet as substrate, put the substrate into ethanol solution for ultrasonic cleaning, and finally clean it with deionized water, blow it dry with nitrogen, and dry it on a hot plate.

[0033] (2) Deposited metal layer 2: 40nm of metallic gold is deposited on the substrate using resistance evaporation technology;

[0034] (3) Coating polymer film 3: PMMA is uniformly coated on the gold film using a spin coater with a thickness of 40nm;

[0035] (4) Coating photoresist 4: Use a spin coater to uniformly coat the PMMA with UV-curable photoresist with a thickness of 150nm;

[0036] (5) Constructing a two-dimensional nanoarray: Select a hexagonal array of nanopores with a unit diameter of 200 nm, a height of 200 nm, and a period of 550 nm as a mask. Transfer the pattern on the mask onto a polymer film using nanoimprinting technology and cure it under ultraviolet light in a nitrogen atmosphere.

[0037] (6) Deposition of one-dimensional multilayer film 6: 20nm Au, 30nm MgF2 and 10nm Au were sequentially deposited on the above two-dimensional nanoarray using resistance evaporation technology.

[0038] Figure 2 This is a SEM image of the surface of a multimode optical resonator composite plasmon. Figure 3 The reflection spectrum of the two-dimensional nanoarray in the 300-800 nm range has a reflection valley at 631 nm and a reflection intensity of 0.87. For example... Figure 4 As shown in Figure a, the designed one-dimensional multilayer film produces a reflection valley at 427 nm, with a corresponding reflection intensity of 0.17. Figure 4b represents the reflection spectrum of the multimode optical resonant cavity composite plasmon surface in the 300-800 nm range, with reflection valleys occurring at 395 nm and 638 nm, and reflection intensities of 0.24 and 0.22, respectively. When a one-dimensional multilayer film is deposited on a two-dimensional nanoarray, the two interact. Furthermore, experimental fabrication introduces certain structural size errors, causing the absorption peak positions of the structure in this invention to shift compared to the peak positions of the individual one-dimensional multilayer film and the two-dimensional nanoarray. Therefore, this structure possesses the spectral characteristics of both a one-dimensional multilayer film and a two-dimensional nanoarray, with a significantly enhanced electromagnetic resonance absorption in the two-dimensional nanoarray, exhibiting a reflection intensity below 0.3 in the 570 nm-670 nm range.

[0039] Example 2:

[0040] The fabrication process of the multimode optical resonator composite plasmon surface in this embodiment is as follows:

[0041] (1) Cleaning of substrate 1: Select polished glass sheet as substrate, put the substrate into ethanol solution for ultrasonic cleaning, and finally clean it with deionized water, blow it dry with nitrogen, and dry it on a hot plate.

[0042] (2) Depositing metal layer 2: Depositing 50nm of metallic silver on the substrate using resistance evaporation technology;

[0043] (3) Coating polymer film 3: PMMA is uniformly coated on the gold film using a spin coater with a thickness of 80nm;

[0044] (4) Coating photoresist 4: Use a spin coater to uniformly coat the PMMA with UV-curable adhesive with a thickness of 200nm; (5) Constructing a two-dimensional nanoarray 5: Select a hexagonal array of nanopores with a unit diameter of 250nm, a height of 300nm, and a period of 600nm as a mask, and transfer the pattern on the mask onto the polymer film using nanoimprint technology, and cure it under UV light in a nitrogen atmosphere;

[0045] (6) Deposition of one-dimensional multilayer film 6: 25nm Ag, 60nm ZnS and 15nm Ag were sequentially deposited on the above two-dimensional nanoarray using resistance evaporation technology.

[0046] like Figure 5 As shown in Figure a, the designed one-dimensional multilayer film produces a reflection valley at 506 nm, with a corresponding reflection intensity of 0.09. Figure 5b represents the reflection spectrum of the multimode optical resonant cavity composite plasmon surface in the 300-800 nm range, with reflection valleys occurring at 533 nm and 625 nm, and reflection intensities of 0.19 and 0.10, respectively. When a one-dimensional multilayer film is deposited on a two-dimensional nanoarray, the two interact. Furthermore, experimental fabrication introduces certain structural size errors, causing the absorption peak positions of the structure in this invention to shift compared to the peak positions of the individual one-dimensional multilayer film and the two-dimensional nanoarray. Therefore, this structure possesses the spectral characteristics of both a one-dimensional multilayer film and a two-dimensional nanoarray, and the electromagnetic resonance absorption of the two-dimensional nanoarray is significantly enhanced, with a reflection intensity below 0.3 in the 485 nm-700 nm range.

[0047] Example 3:

[0048] The fabrication process of the multimode optical resonator composite plasmon surface in this embodiment is as follows:

[0049] (1) Cleaning of substrate 1: Select polished glass sheet as substrate, put the substrate into ethanol solution for ultrasonic cleaning, and finally clean it with deionized water, blow it dry with nitrogen, and dry it on a hot plate.

[0050] (2) Depositing metal layer 2: Depositing 100nm of aluminum metal on the substrate using resistance evaporation technology;

[0051] (3) Coating polymer film 3: PMMA is uniformly coated on the gold film using a spin coater with a thickness of 150nm; (4) Coating photoresist 4: UV-curable adhesive is uniformly coated on the PMMA using a spin coater with a thickness of 250nm; (5) Constructing two-dimensional nanoarray 5: A hexagonal array of nanopores with a unit diameter of 350nm, a height of 400nm, and a period of 650nm is selected as a mask. The pattern on the mask is transferred to the polymer film using nanoimprint technology and cured under UV light in a nitrogen atmosphere.

[0052] (6) Deposition of one-dimensional multilayer film 6: 35nm Al, 120nm MgS and 20nm Al were sequentially deposited on the above two-dimensional nanoarray using resistance evaporation technology.

[0053] like Figure 6 As shown in Figure a, the designed one-dimensional multilayer film produces a reflection valley at 669 nm, with a corresponding reflection intensity of 0.08. Figure 6 b represents the reflection spectrum of the multimode optical resonant cavity composite plasmon surface in the 300-800 nm range. Due to the similarity between the peak positions of the one-dimensional multilayer film and the two-dimensional nanoarray, this structure forms a broad absorption band in the 520-800 nm range, with a reflectivity of less than 0.3. The lowest reflectivity is 0.11 at 682 nm.

Claims

1. A multi-mode optical resonant cavity composite plasmon surface, characterized in that: The material consists of a substrate (1), a metal layer (2) placed on the substrate, a polymer film (3) spin-coated on the metal layer (2), a photoresist (4) spin-coated on the polymer film (3), a two-dimensional nanoarray (5) constructed on the photoresist (4) by nanoimprinting technology, and a one-dimensional multilayer film (6) deposited on the surface of the two-dimensional nanoarray (5); wherein the one-dimensional multilayer film (6) is formed by stacking a metal layer, a dielectric layer, and a metal layer in sequence; the metal layers in the metal layer (2) and the one-dimensional multilayer film (6) are all gold, silver, aluminum or copper.

2. The multi-mode optical resonator composite plasmon surface according to claim 1, characterized in that: The substrate (1) is silicon or glass.

3. The multi-mode optical resonator composite plasmon surface according to claim 1, characterized in that: The thickness of the metal layer (2) placed on the substrate (1) is 40-100 nm.

4. The multi-mode optical resonator composite plasmon surface according to claim 1, characterized in that: The polymer film (3) spin-coated on the metal layer (2) is polymethyl methacrylate or polycarbonate; its thickness is 40-150 nm.

5. The multi-mode optical resonator composite plasmon surface according to claim 1, characterized in that: The photoresist (4) spin-coated on the polymer film (3) is a UV-curable adhesive with a thickness of 150-250 nm.

6. The multimode optical resonator composite plasmon surface according to claim 1, characterized in that: The two-dimensional nanoarray (5) structural unit is a cylinder; the diameter of the two-dimensional nanoarray (5) structural unit is 200-350nm, the height is 200-400nm, and the array period is 550-650nm.

7. The multimode optical resonator composite plasmon surface according to claim 1, characterized in that: The dielectric material of the dielectric layer is magnesium fluoride, zinc selenide, zinc sulfide, or magnesium sulfide.

8. The multimode optical resonator composite plasmon surface according to claim 1, characterized in that: The thicknesses of the one-dimensional multilayer film (6) from bottom to top are 20-35nm, 30-120nm, and 10-20nm, respectively.

9. A method for preparing the multimode optical resonator composite plasmon surface as described in claim 1, comprising the following specific steps: (1) Substrate cleaning: The substrate (1) was placed in an ethanol solution for ultrasonic cleaning, then rinsed with deionized water, dried with nitrogen, and dried on a hot plate. (2) Deposit metal layer: Deposit metal layer on substrate using electron beam evaporation or resistance evaporation technology (2); (3) Coating polymer film: Use a spin coater to uniformly coat polymer film (3) onto metal layer (2); (4) Coating photoresist: Use a spin coater to uniformly coat the polymer film (3) with photoresist (4); (5) Constructing a two-dimensional nanoarray: The pattern on the photomask is transferred onto the photoresist (4) using nanoimprinting technology; (6) Deposition of one-dimensional multilayer film: A one-dimensional multilayer film (6) consisting of a metal layer, a dielectric layer and a metal layer is sequentially deposited on the above two-dimensional nanoarray (5) using electron beam evaporation or resistance evaporation technology.

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