Metamaterial, and method for realizing dynamic manipulation of fluorescence based on metamaterial

Abstract

The application belongs to the technical field of micro-nano optics, and discloses a superstructure crystal and a method for realizing dynamic control of fluorescence based on the superstructure crystal. The superstructure crystal provided by the application comprises a substrate layer as a bottom layer and a hydrogel array layer as a top layer, the hydrogel array layer is prepared by uniformly mixing a hydrogel and a quantum dot solution, the hydrogel array comprises periodically arranged air holes, the optical response of the superstructure crystal depends on the thickness, period and size of the air holes of the hydrogel array layer, and the resonance characteristics of the superstructure crystal dynamically change with the environmental humidity. By changing the environmental humidity, the bound state q-BIC resonance wavelength in the quasi-continuous spectrum of the superstructure crystal is moved, and the wavelength and angle of the incoherent fluorescence emission are dynamically controlled. The application can improve the dynamic control performance of the wavelength and angle of the fluorescence control of the quantum dots, and effectively adjust the fluorescence emission.

Description

Technical Field

[0001] The present invention belongs to the field of micro-nano optical technology, and more specifically, relates to a metacrystal and a method for realizing dynamic fluorescence manipulation based on the metacrystal. Background Art

[0002] In recent years, luminescent metasurfaces have become a research hotspot for next-generation light-emitting devices due to their superior optical controllability and higher integration density. In particular, in the integration of quantum dots and metasurfaces, precise control of the photoluminescence properties of quantum dots can achieve a variety of interesting phenomena, such as emission enhancement, unidirectional emission, and chiral emission. However, the fluorescence control of quantum dots remains challenging, primarily due to omnidirectional emission and limited wavelength tunability. These limitations stem from low spatiotemporal coherence, restricting the application of nanophotonic devices. Summary of the Invention

[0003] The present invention solves the problem in the prior art that the dynamic control performance of fluorescence control of quantum dots in wavelength and angle needs to be improved by providing a metacrystal and a method for realizing dynamic control of fluorescence based on the metacrystal.

[0004] The present invention provides a metacrystal, comprising: a substrate layer as a bottom layer and a hydrogel array layer as a top layer; the hydrogel array layer is prepared by uniformly mixing a hydrogel and a quantum dot solution, and the hydrogel array contains periodically arranged air holes; the optical response of the metacrystal depends on the thickness and period of the hydrogel array layer and the size of the air holes, and the resonance characteristics of the metacrystal change dynamically with the ambient humidity.

[0005] Preferably, the metacrystal supports bound-state BIC modes in the continuous spectrum in the visible light range.

[0006] Preferably, when the ambient humidity changes, the morphology of the hydrogel array layer changes dynamically, and the bound-state BIC mode in the continuous spectrum supported by the metacrystal moves.

[0007] Preferably, the hydrogel is a hydrogel material that expands in response to humidity.

[0008] Preferably, the hydrogel array layer is prepared by uniformly mixing a polyvinyl alcohol aqueous solution and a carbon quantum dot solution.

[0009] Preferably, the hydrogel array layer is prepared by electron beam exposure and deionized water development.

[0010] Preferably, the substrate layer is a metal substrate layer, and the metal substrate layer is made of gold, silver or aluminum; the incident light is totally reflected after passing through the metal substrate layer.

[0011] Preferably, the air holes are square holes; the thickness of the hydrogel array layer is 280nm to 330nm, the period is 460nm to 540nm, the side length of the square holes is 320nm to 360nm; the thickness of the substrate layer is 80nm to 100nm.

[0012] On the other hand, the present invention provides a method for achieving dynamic manipulation of fluorescence based on the above-mentioned metacrystal. By changing the ambient humidity, the bound state q-BIC resonance wavelength in the quasi-continuous spectrum of the metacrystal is shifted, thereby achieving dynamic manipulation of the wavelength and angle of incoherent fluorescence emission.

[0013] Preferably, as the ambient humidity increases, the hydrogel array layer in the metacrystal expands and the air pores in the metacrystal shrink, causing the bound-state q-BIC resonance wavelength in the quasi-continuous spectrum supported by the metacrystal to red-shift, thereby achieving dynamic regulation of the bound-state BIC mode in the continuous spectrum.

[0014] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0015] (1) The metacrystal provided by the present invention includes a substrate layer as a bottom layer and a hydrogel array layer as a top layer. The hydrogel array layer is prepared by uniformly mixing a hydrogel and a quantum dot solution. The hydrogel array contains periodically arranged air holes. The optical response of the metacrystal depends on the thickness and period of the hydrogel array layer and the size of the air holes. The resonance characteristics of the metacrystal change dynamically with the ambient humidity. By changing the ambient humidity, the present invention can shift the resonant wavelength of the bound states in the quasi-continuum (q-BIC) of the metacrystal, thereby achieving dynamic manipulation of the wavelength and angle of incoherent fluorescence emission.

[0016] Based on the unique properties of bound states in the continuum (BIC) that suppress radiation loss and possess ultra-high quality factors, the present invention uses BIC as a way to address the challenges currently faced in fluorescence regulation of quantum dots. By destroying the symmetry of metaatoms, BIC can be converted into q-BIC, thereby enhancing the light-matter interaction with active luminescent materials. Based on the characteristics of hydrogels that have both transparent optical properties and scalability, hydrogels can be used to achieve dynamic size adjustment through the moisture absorption / dehydration process. The present invention uses hydrogels as materials compatible with the BIC effect and used to regulate fluorescence emission. By utilizing the excellent water absorption and expansion properties of hydrogels, the morphology of the metacrystal is changed by controlling the ambient humidity, thereby causing the supported BIC mode to move, giving the BIC structure dynamic regulation capabilities, overcoming the problem that traditional BIC metasurfaces are difficult to dynamically regulate. q-BIC with high-quality factor resonance is realized and regulated in the hydrogel medium, which can achieve effective regulation of fluorescence emission. That is, the present invention provides a dynamic fluorescence manipulation scheme combining BIC with humidity, which can improve the dynamic manipulation performance of quantum dots in fluorescence regulation in wavelength and angle, and help expand the application of nanophotonic devices.

[0017] In summary, the quantum dot-integrated hydrogel metacrystal designed in the present invention couples fluorescence radiation with the q-BIC mode, enhancing the fluorescence emission intensity and enabling it to inherit the reflectance spectral characteristics of q-BIC, thereby realizing the regulation of fluorescence emission wavelength and angle. In addition, by utilizing the swelling characteristics of the hydrogel, dynamic regulation of fluorescence at different humidity levels is achieved, providing a promising implementation approach for dynamic manipulation of incoherent radiation and biocompatible fluorescence imaging.

[0018] (2) In the preparation process of traditional fluorescence-controlled metasurfaces, the deposition of quantum dots is often processed by dripping or spin coating. That is, traditional fluorescence deposition generally involves spin coating or drop casting of quantum dot solutions on the already processed metasurface. Such secondary processing cannot ensure the uniformity between quantum dots and micro-nanostructures. This processing method will bring unpredictable processing defects, which in turn affect the quality factor of BIC. The hydrogel array layer in the present invention is prepared by uniformly mixing hydrogel and quantum dot solution. That is, the present invention utilizes the good compatibility of hydrogel to embed quantum dots into the interior of the hydrogel material, and forms a periodic hydrogel array with air holes through a two-step process of electron beam exposure and deionized water washing and development. Compared with existing research, the present invention abandons the subsequent complex thermal evaporation and etching process, thereby improving the sample preparation efficiency. The metacrystal designed by the present invention has the advantage of high integration and does not require secondary processing, which greatly improves the performance parameters of BIC.

[0019] (3) By designing the structural parameters of the metacrystal, the metacrystal provided by the present invention supports bound-state BIC modes in the continuous spectrum within the visible light range. Under low-angle oblique incidence (less than 8°), it can support q-BIC resonances with narrow bandwidth and high quality factors. This invention overcomes the disadvantage that most traditional BIC structures only support BICs in the near-infrared region, and provides a new paradigm for BIC design in the visible light region. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a metacrystal according to an embodiment of the present invention for achieving dynamic fluorescence manipulation;

[0021] Figure 2 Schematic diagram of the superstructure crystal and BIC regulation provided by an embodiment of the present invention; wherein, Figure 2 (a) is a schematic diagram of the structure of the supercrystal. Figure 2 (b) is a schematic diagram of BIC regulation;

[0022] Figure 3 : is a simulation effect diagram of the polarization field distribution and quality factor of the BIC mode in an embodiment of the present invention; wherein, Figure 3 (a) is the simulation effect diagram under dry environment. Figure 3 (b) is the simulation effect diagram under a humid environment;

[0023] Figure 4 This is a simulation effect diagram of the reflection spectrum of y-polarized light at different incident angles and the electric field distribution at a wavelength of 595nm in dry and humid environments according to an embodiment of the present invention;

[0024] Figure 5 1 is a simulation effect diagram of the change of q-BIC reflection spectrum with angle under different humidity in an embodiment of the present invention;

[0025] Figure 6 is an experimental diagram of a metacrystal sample obtained using optical and scanning electron microscopes in an embodiment of the present invention; wherein, Figure 6 (a) is the sample morphology obtained using an optical microscope. Figure 6 (b) is the sample morphology obtained by scanning electron microscopy;

[0026] Figure 7 1 is an experimental effect diagram of the y-polarized light reflection spectrum of the metacrystal in an embodiment of the present invention;

[0027] Figure 8 1 is an experimental effect diagram of the reflection spectrum of the metacrystal under different humidity conditions according to an embodiment of the present invention;

[0028] Figure 9This is an experimental effect diagram of the dynamic shift of the q-BIC resonance wavelength of the metacrystal under different humidity conditions in an embodiment of the present invention; Figure 9 (a) is a schematic diagram of the change of the q-BIC resonance peak near 610nm with relative humidity. Figure 9 (b) is the experimental effect diagram of the change of q-BIC resonance wavelength with incident angle;

[0029] Figure 10 : is an experimental effect diagram of the metacrystal reflection spectrum in an embodiment of the present invention; wherein, Figure 10 (a) is the experimental effect diagram under x polarization. Figure 10 (b) is the experimental effect diagram under y polarization;

[0030] Figure 11 : is an experimental effect diagram of the supercrystal fluorescence test in an embodiment of the present invention; wherein, Figure 11 (a) is a schematic diagram of a supercrystal. Figure 11 (b) is the fluorescence characterization result of the metacrystal in a wide band. Figure 11 (c) shows the fluorescence characterization results of the metacrystal in a narrow wavelength band;

[0031] Figure 12 : is an experimental device for the fluorescence test of the metacrystal and an experimental effect diagram of the emission angle test in an embodiment of the present invention; wherein, Figure 12 (a) is the experimental setup diagram. Figure 12 (b) is the experimental effect diagram of the emission angle test;

[0032] Figure 13 This is a diagram showing the dynamic fluorescence test experiment results of the metacrystal under different humidity conditions in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0034] Example 1:

[0035] Example 1 provides a metacrystal, comprising: a substrate layer as a bottom layer and a hydrogel array layer as a top layer; the hydrogel array layer is prepared by uniformly mixing a hydrogel and a quantum dot solution, and the hydrogel array contains periodically arranged air holes; the optical response of the metacrystal depends on the thickness and period of the hydrogel array layer and the size of the air holes, and the resonance characteristics of the metacrystal change dynamically with the ambient humidity.

[0036] Specifically, the metacrystal includes a periodically arranged hydrogel array, which can produce a symmetric protected BIC with infinite high quality factor under normal incidence. The BIC wavelength of the metacrystal is determined by the structural parameters of the hydrogel array, and the BIC wavelength of the metacrystal matches the fluorescence emission wavelength of the quantum dots.

[0037] The metacrystal supports BIC modes in the visible light range.

[0038] When the ambient humidity changes, the morphology of the hydrogel array layer changes dynamically, and the BIC pattern supported by the metacrystal moves.

[0039] Because BIC has an infinite quality factor, it cannot be observed in the spectrum. However, when the y-polarized incident light is incident normally, the metacrystal can transform the BIC into a q-BIC with a finite quality factor by slightly adjusting the incident angle along the x-direction. This allows it to be observed in the spectrum, while still maintaining an extremely high quality factor.

[0040] The hydrogel is a hydrogel material that expands in response to humidity.

[0041] For example, the hydrogel array layer can be prepared by uniformly mixing a polyvinyl alcohol aqueous solution and a carbon quantum dot solution. Carbon quantum dots embedded within the hydrogel can be excited by obliquely incident pump light. The fluorescence emission has a bandwidth of 40 nm and can be emitted and polarized in any direction.

[0042] The broadband y-polarized fluorescence is modulated by the BIC in the metacrystal. Since the q-BIC resonance wavelength changes with angle, the fluorescence emission wavelength regulated by the BIC is angle-dependent.

[0043] Since the BIC mode of the metacrystal is regulated by the ambient humidity, the fluorescence enhanced by q-BIC exhibits dynamic emission characteristics that change with humidity, and the emission angles of fluorescence components of different wavelengths can change dynamically.

[0044] Specifically, the hydrogel array layer is prepared by electron beam exposure and deionized water development.

[0045] The substrate layer is a metal substrate layer, and the metal substrate layer is made of gold, silver or aluminum; the incident light is totally reflected after passing through the metal substrate layer.

[0046] For example, the air holes can be square holes, the hydrogel array layer can have a thickness of 280 nm to 330 nm, a period of 460 nm to 540 nm, and a side length of 320 nm to 360 nm, to support BIC in the visible light range. For example, the substrate layer can be a silver substrate layer with a thickness of 80 nm to 100 nm to ensure total internal reflection of light at the substrate layer interface.

[0047] In summary, the metacrystal provided in Example 1 is specifically a quantum dot integrated hydrogel metacrystal. By using an electron beam exposure process and deionized water development, a hydrogel metacrystal with air holes can be printed on the surface of a hydrogel film, that is, a hydrogel nanoarray with air holes is prepared on the surface of a metal substrate. By designing the structural parameters of the metacrystal, a BIC mode with a high quality factor can be achieved in the visible light range; by utilizing the dynamic adjustability of the morphology of the hydrogel metalattice, the metacrystal can achieve dynamic regulation of BIC when the ambient humidity changes. The BIC wavelength matches the fluorescence emission wavelength of the quantum dots, and the fluorescence emission can be coupled with the dynamic quasi-BIC (q-BIC) resonance mode to achieve enhancement of the fluorescence emission and dynamic manipulation of the emission angle. The hydrogel metacrystal based on quantum dot integration proposed in the present invention has the characteristics of high integration and dynamic manipulation, and is expected to be applied to biosensing, biocompatible fluorescence imaging and dynamic fluorescence lasers, providing a new approach for dynamic integrated optical systems.

[0048] On the basis of Example 1, the present invention can also realize dynamic manipulation of fluorescence based on the metacrystal provided in Example 1, which is described below with Example 2.

[0049] Example 2:

[0050] Example 2 provides a method for dynamic manipulation of fluorescence based on metacrystals. By changing the ambient humidity, the bound-state q-BIC resonance wavelength in the quasi-continuous spectrum of the metacrystal as described in Example 1 is shifted, thereby achieving dynamic manipulation of the wavelength and angle of incoherent fluorescence emission.

[0051] Specifically, as the ambient humidity increases, the hydrogel array layer in the metacrystal expands and the air pores in the metacrystal contract, causing the bound-state q-BIC resonance wavelength in the quasi-continuous spectrum supported by the metacrystal to redshift, thereby achieving dynamic regulation of the bound-state BIC mode in the continuous spectrum.

[0052] In this invention, quantum dots are embedded in a hydrogel, and the broadband y-polarized fluorescence emitted is modulated and enhanced by the q-BIC in the metacrystal. Because the q-BIC resonant wavelength changes with angle, the wavelength of the fluorescence emission modulated by the q-BIC exhibits angle dependence. By varying the ambient humidity to shift the q-BIC resonant wavelength, the wavelength and angle of the incoherent fluorescence emission can be dynamically manipulated.

[0053] The technical principle and research process of the present invention are as follows:

[0054] Unlike traditional resonant modes, BICs, or bound states within the continuum, are solutions to wave equations. They lie within the continuum of energy states and have attracted widespread attention in nanophotonics for their unique ability to manipulate light-matter interactions. BICs provide highly localized modes that effectively suppress radiative losses. Different radiation modes interfere with each other and cancel each other, exhibiting a dark state characteristic with a near-infinite high quality factor that cannot be observed in the spectrum. By breaking the symmetry of metaatoms, BICs can be transformed into q-BICs, or quasi-BICs. These quasi-bound states maintain a very high but finite quality factor, resulting in resonant peaks that can be observed in the spectrum. When resonant structures with high quality factors are integrated with active light-emitting materials, the fluorescence radiation couples with the q-BIC modes, causing the radiation spectrum to inherit the q-BIC spectral characteristics.

[0055] First, we need to determine whether the structure can generate a BIC mode. The most important criterion is whether the generated mode is the center of the polarization vortex in the radiation field. From a theoretical point of view, the polarization of the far-field radiation is projected onto the known mode (ω, k || )’s eigenfield distribution E(x,y,z)=[E x (x,y,z),E y (x,y,z),E z (x,y,z)]. Then use the same frequency ω and in-plane wave vector k || =(k x ,k y ), the plane wave electric field with normalized amplitude Integrating into the eigenfield distribution, we get three orthogonal far-field components c(k || )=(c x ,c y ,c z ), which is expressed as follows:

[0056]

[0057] The integration surface is the xy plane, located above or below the structure, corresponding to the upward or downward radiation, respectively. Here, the polarization vector on the xy plane is directly expressed as:

[0058]

[0059] After constructing the field, we also need to define the number of revolutions around the central polarization singular point, which has topological significance, namely the topological charge (q). We first define the number of revolutions around the central polarization singular point according to c || The polarization state principal axis φ(k || ) and then calculate the number of revolutions using the following formula:

[0060]

[0061] Where C is a small closed curve around the polarization singularity. When q is an integer, the resulting mode is the BIC mode.

[0062] The present invention is further illustrated below with reference to parameters.

[0063] Figure 1 The schematic diagram of the metacrystal designed for the present invention to achieve dynamic fluorescence control, that is, the overall function of the metacrystal is demonstrated. The following description includes the early simulation of the BIC mode and the dynamic q-BIC experimental verification. The schematic diagram of the metacrystal and BIC control is shown in the figure. Figure 2 As shown, Figure 2 (a) is a schematic diagram of the structure of the supercrystal. Figure 2 (b) is a schematic diagram of BIC regulation. Figure 2 The metacrystal consists of a silver substrate at the bottom and a periodic hydrogel array structure at the top and has square-structured air holes, wherein the thickness of the silver substrate is 80nm, the thickness H of the hydrogel is 280nm, the refractive index of the hydrogel is 1.51, and the array period P is 520nm.

[0064] In this metalattice, BIC formation arises from destructive interference between different radiation channels. As the relative humidity increases, the hydrogel array expands, causing the air pores to contract. This morphological change redshifts the resonant wavelength of the q-BIC supported by the periodic nanostructure, thereby enabling dynamic regulation of the BIC mode.

[0065] In order to gain a deeper understanding of the dynamic optical properties of the metalattice, the present invention uses two different nanostructures (thicknesses of 260 nm and 280 nm, and air hole side lengths of 360 nm and 320 nm, respectively) to simulate the BIC mode characteristics under different humidity conditions. Figure 3 The quality factor and far-field polarization state of the BIC mode in momentum space are shown. Figure 3 (a) is the simulation effect diagram under dry environment. Figure 3(b) shows the simulation effect in a humid environment. The simulation results show that the quality factor is infinite at the center of the polarization field, and the singularity of the polarization vortex indicates that its topological charge is +1.

[0066] Figure 4 The evolution of the y-polarized reflectance spectrum and the electric field at a wavelength of 595 nm (q-BIC mode is supported when y-polarized light is incident at 2° in a dry environment) under different humidity conditions is shown. For dry conditions, the electric field in the yz plane is confined to the hydrogel array under the excitation of y-polarized incident light at an inclined incident angle of 2°, which suppresses far-field radiation losses, indicating that the q-BIC mode has an extremely high quality factor. In contrast, when the hydrogel swells under wet conditions, the electric field intensity at 595 nm drops significantly, resulting in energy leakage, thereby achieving active regulation of the q-BIC resonance. In addition, by comparing the q-BIC peaks in the dry and wet states, a difference of 25 nm in the resonance wavelength can be observed (see Figure 5 ), so it is expected that dynamic regulation of q-BIC resonance can be achieved by changing the ambient humidity in the experiment.

[0067] The above structure was prepared by electron beam lithography in the experiment, see Figure 6 .in, Figure 6 (a) is the sample morphology obtained using an optical microscope. Figure 6 (b) shows the sample morphology obtained using a scanning electron microscope.

[0068] Figure 7 The reflection spectra at different oblique incident angles (from 0° to 7°) were plotted, and it can be seen that the resonance wavelength of the q-BIC mode shifted from 597nm to 613nm, the minimum line width was about 3.2nm, and the quality factor could reach 200. Based on this, tests were conducted under different humidity conditions. As the relative humidity increased, the volume of the air pores gradually decreased, and the thickness of the hydrogel layer expanded due to the absorption of environmental water molecules, such as Figure 8 As the BIC properties of the designed structure are highly dependent on the size of the air pores, changes in the hydrogel morphology lead to a continuous red shift in the resonance wavelength, thus achieving active regulation of q-BIC in the visible spectrum. Figure 9 The angle-resolved spectral changes at different relative humidity are shown, among which, Figure 9 (a) is a schematic diagram of the change of the q-BIC resonance peak near 610nm with relative humidity. Figure 9 (b) is an experimental effect diagram of the change of q-BIC resonance wavelength with incident angle; the results show that when the relative humidity increases from 30% to 90%, the wavelength range of q-BIC resonance can reach 10nm; when the relative humidity is lower than 50%, the expansion rate of the hydrogel is low, so only a slight wavelength shift occurs when the relative humidity increases from 30% to 50%.

[0069] To achieve incoherent emission enhancement and dynamic manipulation capabilities, we embedded quantum dots into hydrogel metacrystals. The quantum dot-hydrogel solution was prepared by mixing a carbon quantum dot solution with a 10.7 wt% polyvinyl alcohol aqueous solution at a ratio of 1:9. To adjust the wavelength range of q-BIC to match the broad-band emission range of fluorescence, the period was set to 460 nm, and the reflectance spectrum of the sample was measured. Figure 10 ,in, Figure 10 (a) is the experimental effect diagram under x polarization. Figure 10 (b) shows the experimental results under y-polarization. When the incident light is incident on the y-polarization, a BIC mode is observed near 596 nm in the reflection spectrum.

[0070] Figure 11 The schematic diagram of quantum dot integrated hydrogel metacrystal and the related fluorescence characterization results are shown in the figure. Figure 11 (a) is a schematic diagram of a supercrystal. Figure 11 (b) is the fluorescence characterization result of the metacrystal in a wide band. Figure 11 (c) in the figure is the fluorescence characterization result of the metacrystal in a narrow band. Specifically, the test results of the wide-band carbon quantum dot film show a broadband emission peak located at 575nm with a bandwidth of about 40nm. In the fluorescence test of the metacrystal, 532nm fluorescence was used to excite the fluorescence emission of the carbon quantum dots, and the y-polarized fluorescence emission spectra at different output angles were recorded. The spectrum inherited the q-BIC spectral characteristics of the metacrystal and showed a fluorescence enhancement effect, which was mainly attributed to the increase in radiation emissivity caused by the Purcell effect at the emission wavelength, which was caused by the strong near-field enhancement of the q-BIC mode. Compared with the omnidirectional emission of the carbon quantum dot film, the quantum dot integrated hydrogel metacrystal showed twice the fluorescence enhancement within the output angle range of ±5°, and the divergence angle could reach 1.4°, see Figure 12 ,in, Figure 12 (a) is the experimental setup diagram. Figure 12 (b) is the experimental effect diagram of the emission angle test.

[0071] In order to verify the dynamic control capability of fluorescence under different humidity conditions, the fluorescence emission spectra under different humidity environments were tested in the experiment, such as Figure 13 As shown, two ambient humidity conditions (relative humidity of approximately 30% and 70%, respectively) were tested. As the relative humidity increased from 30% to 70%, the narrowband enhanced emission peak collected at a 3° exit angle actively red-shifted from approximately 598nm to approximately 601nm. This demonstrates that the morphological changes of the metacrystals provided by this invention at different humidity levels provide the designed device with dynamic control capabilities.

[0072] Through simulation and experiments, the present invention verifies that the quantum dot-integrated hydrogel metacrystal designed by the present invention can achieve dynamic BIC, fluorescence enhancement, and active manipulation, overcoming the limitation of traditional BIC structures that can only achieve static regulation due to the material stability characteristics of nanounits. At the same time, while maintaining high integration, the preparation process of the metacrystal is simplified, the unknown defects caused by secondary processing when introducing quantum dots are avoided, and the performance of the device is improved.

[0073] In summary, the metacrystals proposed in this paper can support a well-formulated BIC mode and exhibit excellent dynamic response characteristics. The hydrogel-based metacrystal design offers significant flexibility in device integration and practical manufacturing feasibility, providing a novel design approach for nanophotonic devices used for active BIC regulation and dynamic fluorescence manipulation. Simultaneously, the simplified device manufacturing process facilitates practical operations for relevant technical personnel, improves device processing yield, and provides a new feasible implementation method for the dynamic manipulation of incoherent light.

[0074] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A metacrystal, characterized in that: include: A substrate layer serves as the bottom layer and a hydrogel array layer serves as the top layer; the hydrogel array layer is prepared by uniformly mixing a hydrogel and a quantum dot solution, the hydrogel adopts a hydrogel material that expands in response to humidity, and the hydrogel array layer contains periodically arranged air holes; the optical response of the metacrystal depends on the thickness and period of the hydrogel array layer and the size of the air holes, and the resonance characteristics of the metacrystal change dynamically with the ambient humidity; by changing the ambient humidity, the bound state q-BIC resonance wavelength in the quasi-continuous spectrum of the metacrystal is moved, thereby realizing dynamic manipulation of the wavelength and angle of incoherent fluorescence emission; the BIC wavelength matches the fluorescence emission wavelength of the quantum dots, and the fluorescence emission is coupled with the dynamic quasi-BIC resonance mode to realize the enhancement of the fluorescence emission and the dynamic manipulation of the emission angle.

2. The metacrystal according to claim 1, wherein: The metacrystal supports bound-state BIC modes in the continuum spectrum in the visible light range.

3. The metacrystal according to claim 1, wherein: When the ambient humidity changes, the morphology of the hydrogel array layer changes dynamically, and the bound-state BIC mode in the continuous spectrum supported by the metacrystal moves.

4. The metacrystal according to claim 1, wherein: The hydrogel array layer is prepared by uniformly mixing a polyvinyl alcohol aqueous solution and a carbon quantum dot solution.

5. The metacrystal according to claim 1, wherein: The hydrogel array layer is prepared by electron beam exposure and deionized water development.

6. The metacrystal according to claim 1, wherein: The substrate layer is a metal substrate layer, and the metal substrate layer is made of gold, silver or aluminum; the incident light is totally reflected after passing through the metal substrate layer.

7. The metacrystal according to claim 1, wherein: The air holes are square holes; the thickness of the hydrogel array layer is 280 nm to 330 nm, the period is 460 nm to 540 nm, the side length of the square holes is 320 nm to 360 nm; the thickness of the substrate layer is 80 nm to 100 nm.

8. A method for dynamic fluorescence manipulation based on the metacrystal according to any one of claims 1 to 7, characterized in that: By changing the ambient humidity, the bound-state q-BIC resonance wavelength in the quasi-continuum spectrum of the metacrystal is shifted, enabling dynamic manipulation of the wavelength and angle of incoherent fluorescence emission.

9. The method for dynamic fluorescence manipulation based on metacrystals according to claim 8, characterized in that: As the ambient humidity increases, the hydrogel array layer in the metacrystal expands and the air pores in the metacrystal shrink, causing the bound-state q-BIC resonance wavelength in the quasi-continuous spectrum supported by the metacrystal to redshift, thereby achieving dynamic regulation of the bound-state BIC mode in the continuous spectrum.

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