An ultraviolet broadband light absorber based on graphene and multilayer periodic structure

Abstract

The application relates to the field of optical materials and nanostructure technology, and particularly relates to a kind of ultraviolet broadband light absorber based on graphene and multilayer periodic structure.The structure of the ultraviolet broadband light absorber is sequentially from top to bottom as follows: a graphene layer, a distributed Bragg reflection grating structure layer, and a SiO2 substrate at the bottom.The preparation process of the ultraviolet broadband light absorber comprises the following steps: graphene layer preparation;SiO2 layer deposition;TiO2 layer deposition;multilayer superposition;graphene layer addition;and device completion.The application greatly improves the light absorption efficiency of graphene in the ultraviolet waveband, realizes broadband and efficient absorption in the wavelength range of 240-370 nm, the highest absorption rate can reach 99.75%, and the absorber is not sensitive to polarization and the preparation process is simple, which provides technical support for the design of high-efficiency ultraviolet light absorber.

Description

Technical Field

[0001] This invention relates to the field of optical materials and nanostructures, specifically to a broadband ultraviolet light absorber based on graphene and a multilayer periodic structure. Background Technology

[0002] With the rapid development of nanophotonics technology, high-efficiency, broadband light absorbers play an indispensable role in fields such as photoelectric detection, solar cells, and biochemical sensing. The core objective of these devices is to achieve efficient light capture and utilization, especially with excellent light absorption performance over a wide wavelength range. However, achieving this goal requires meticulous optimization in material selection and structural design.

[0003] In recent years, graphene has become an important material for absorber design due to its broad-spectrum absorption capabilities. As a two-dimensional carbon material, graphene exhibits unique photoelectric properties across the entire visible and ultraviolet light range. It possesses not only extremely high carrier mobility but also broadband optical response characteristics. However, the light absorption rate of monolayer graphene is only 2.3%, primarily due to the thinness of its single atomic layer, resulting in weak light-material interaction, which limits the direct application of monolayer graphene in high-efficiency light absorbers. In the infrared and visible light bands, various graphene-based absorber designs have achieved high absorption rates. For example, near-perfect absorption in the visible light range can be achieved through a composite structure based on graphene and a one-dimensional photonic crystal. However, the absorption efficiency of graphene-based absorbers in the ultraviolet band is generally low. For example, the utility model patent CN213843569U, entitled "A Multilayer Thin Film Structure Based on Bragg Grating / Metal Thin Film", discloses a multilayer film structure that can improve the light absorption efficiency of graphene in the ultraviolet region. This structure can effectively enhance the interaction between ultraviolet light and graphene, increasing the absorption peak of graphene at a wavelength of 275nm to 95.34%. However, this absorption rate is still low and cannot meet the needs of specific application scenarios.

[0004] To address the aforementioned issues, this invention provides a broadband ultraviolet light absorber based on graphene and a multilayer periodic structure, aiming to provide a light absorption structure with broadband high absorption in the ultraviolet band, thus providing technical support for the design of efficient ultraviolet light absorbers. Summary of the Invention

[0005] The purpose of this invention is to provide a broadband ultraviolet light absorber based on graphene and a multilayer periodic structure.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The structure of the ultraviolet broadband light absorber based on graphene and multilayer periodic structure described in this invention consists of a graphene layer, a distributed Bragg grating structure layer, and a SiO2 substrate from top to bottom; wherein the distributed Bragg grating structure layer is composed of periodic units stacked from any one of the dielectric materials selected from Na3AlF6, SiO2, and KCl and TiO2.

[0008] Preferably, in the ultraviolet broadband light absorber based on graphene and multilayer periodic structure of the present invention, the distributed Bragg grating structure layer is composed of stacked periodic units composed of SiO2 and TiO2, and the number of periodic unit layers is 2-8.

[0009] In a further preferred embodiment, in the ultraviolet broadband light absorber based on graphene and a multilayer periodic structure described in this invention, the distributed Bragg grating structure layer is composed of stacked periodic units of SiO2 and TiO2, with the number of periodic unit layers being 4-8.

[0010] In a further preferred embodiment, in the ultraviolet broadband light absorber based on graphene and a multilayer periodic structure described in this invention, the distributed Bragg grating structure layer is composed of stacked periodic units of SiO2 and TiO2, with a periodic unit layer number of 6.

[0011] Preferably, in the ultraviolet broadband absorber based on graphene and multilayer periodic structure of the present invention, in the periodic unit of the distributed Bragg grating structure layer: the thickness of the SiO2 layer is 48.26 nm and the refractive index is 1.45; the thickness of the TiO2 layer is 25.74 nm and the refractive index is 2.72.

[0012] Preferably, in the ultraviolet broadband absorber based on graphene and multilayer periodic structure of the present invention, the thickness of the graphene layer is 0.34 nm.

[0013] Preferably, in the ultraviolet broadband light absorber based on graphene and multilayer periodic structure of the present invention, the thickness of the SiO2 substrate is greater than 2 μm.

[0014] The fabrication method of the ultraviolet broadband light absorber based on graphene and multilayer periodic structure according to the present invention includes the following steps:

[0015] S1. Preparation of graphene layer:

[0016] Graphene was grown on a copper substrate using chemical vapor deposition (CVD). The copper substrate was placed in a CVD reactor and methane was introduced to deposit the graphene. After growth, a polymer film was used to transfer the graphene onto a pre-prepared SiO2 substrate.

[0017] Deposition of S2 and SiO2 layers:

[0018] After the graphene layer was transferred onto the SiO2 substrate, an electron beam evaporation method was used to deposit a SiO2 thin film. The deposition time and power were adjusted to ensure that the thickness of each SiO2 layer was 48.26 nm.

[0019] Deposition of S3 and TiO2 layers:

[0020] A TiO2 layer was deposited on a SiO2 layer using reactive magnetron sputtering. The oxygen flow rate and power were controlled to ensure that the thickness of the TiO2 layer was 25.74 nm and the refractive index reached 2.72.

[0021] S4, Multi-layer stacking:

[0022] Repeatedly deposit SiO2 and TiO2 layers until the required total number of layers is reached;

[0023] S5, Additional graphene layer:

[0024] The graphene layer was accurately aligned and placed on the interface of the periodic unit composed of SiO2 and TiO2 layers;

[0025] S6. Device completed:

[0026] The prepared multilayer structure is finely processed using photolithography and etching techniques to form the required device shape, and then the subsequent electrical contact and packaging processes are completed to obtain the final product.

[0027] The beneficial effects of this invention are:

[0028] This invention provides a broadband ultraviolet light absorber based on graphene and a multilayer periodic structure. By optimizing the grating structure parameters, the light absorption efficiency of graphene in the ultraviolet band is greatly improved, achieving broadband and efficient absorption in the wavelength range of 240–370 nm, with an absorption rate of up to 99.75% and a full width at half maximum (FWHM) of 115 nm. Furthermore, the device has a simple fabrication process, is insensitive to light polarization, and exhibits wide-angle absorption characteristics. This invention provides technical support for the design of high-efficiency ultraviolet light absorbers. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the main structure of a UV broadband light absorber based on graphene and a multilayer periodic structure (in the figure: ① is the graphene layer; ② is the SiO2 layer; ③ is the TiO2 layer);

[0030] Figure 2 The reflection spectrum of a distributed Bragg reflector in the ultraviolet range when the number of SiO2 / TiO2 periodic unit layers is 6.

[0031] Figure 3The absorption spectra of ultraviolet light absorbers with different refractive index ratios of the dielectric layers;

[0032] Figure 4 The absorption spectra of ultraviolet light absorbers under different polarization states of incident light;

[0033] Figure 5 The absorption spectra of ultraviolet light absorbers under normal incidence conditions for different numbers of SiO2 / TiO2 periodic unit layers;

[0034] Figure 6 The absorption spectra of the ultraviolet absorber are shown at different incident light angles. Detailed Implementation

[0035] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The following embodiments are for explanation and illustration only, and do not constitute a limitation on the technical solution of the present invention.

[0036] Example 1

[0037] The ultraviolet broadband absorber based on graphene and a multilayer periodic structure consists of, from top to bottom, a graphene layer, a distributed Bragg grating structure composed of six stacked periodic units of SiO2 and TiO2, and a SiO2 substrate. The graphene layer is 0.34 nm thick; the SiO2 layer in the periodic unit of the distributed Bragg grating structure is 48.26 nm thick with a refractive index of 1.45, the TiO2 layer is 25.74 nm thick with a refractive index of 2.72, and the SiO2 substrate is 3 μm thick.

[0038] Example 2

[0039] The ultraviolet broadband absorber based on graphene and a multilayer periodic structure consists of, from top to bottom, a graphene layer, a distributed Bragg grating structure composed of two stacked periodic units of SiO2 and TiO2, and a SiO2 substrate. The graphene layer is 0.34 nm thick; the SiO2 layer in the periodic unit of the distributed Bragg grating structure is 48.26 nm thick with a refractive index of 1.45, the TiO2 layer is 25.74 nm thick with a refractive index of 2.72, and the SiO2 substrate is 3 μm thick.

[0040] Example 3

[0041] The ultraviolet broadband absorber based on graphene and a multilayer periodic structure consists of, from top to bottom, a graphene layer, a distributed Bragg grating structure composed of four periodic units of SiO2 and TiO2, and a SiO2 substrate. The graphene layer is 0.34 nm thick; the SiO2 layer in the periodic unit of the distributed Bragg grating structure is 48.26 nm thick with a refractive index of 1.45, the TiO2 layer is 25.74 nm thick with a refractive index of 2.72, and the SiO2 substrate is 3 μm thick.

[0042] Example 4

[0043] The ultraviolet broadband absorber based on graphene and a multilayer periodic structure consists of, from top to bottom, a graphene layer, a distributed Bragg grating structure composed of eight periodic units of SiO2 and TiO2, and a SiO2 substrate. The graphene layer is 0.34 nm thick; the SiO2 layer in the periodic unit of the distributed Bragg grating structure is 48.26 nm thick with a refractive index of 1.45, the TiO2 layer is 25.74 nm thick with a refractive index of 2.72, and the SiO2 substrate is 3 μm thick.

[0044] Example 5

[0045] The ultraviolet broadband absorber based on graphene and a multilayer periodic structure consists of, from top to bottom, a graphene layer, a distributed Bragg grating structure composed of six periodic units of Na3AlF6 and TiO2, and a SiO2 substrate. The graphene layer is 0.34 nm thick; the Na3AlF6 layer in the periodic unit of the distributed Bragg grating structure is 52.63 nm thick with a refractive index of 1.33, the TiO2 layer is 25.74 nm thick with a refractive index of 2.72, and the SiO2 substrate is 3 μm thick.

[0046] Example 6

[0047] The ultraviolet broadband absorber based on graphene and a multilayer periodic structure consists of, from top to bottom, a graphene layer, a distributed Bragg grating structure composed of six stacked periodic units of KCl and TiO2, and a SiO2 substrate. The graphene layer is 0.34 nm thick; the KCl layer in the periodic unit of the distributed Bragg grating structure is 46.98 nm thick with a refractive index of 1.49, the TiO2 layer is 25.74 nm thick with a refractive index of 2.72, and the SiO2 substrate is 3 μm thick.

[0048] Example 7

[0049] Fabrication process of ultraviolet broadband light absorbers based on graphene and multilayer periodic structures:

[0050] (1) Preparation of graphene layer: monolayer graphene was grown on copper substrate by chemical vapor deposition (CVD). The copper substrate was placed in a CVD reactor and methane was introduced to deposit graphene. After the growth was completed, a polymer film was used to transfer the graphene onto a pre-prepared SiO2 substrate.

[0051] (2) Deposition of SiO2 layer: After the graphene layer is transferred to the SiO2 substrate, SiO2 film is deposited by electron beam evaporation. The deposition time and power are adjusted to control the thickness of SiO2 and ensure that the thickness of each SiO2 layer is 48.26 nm.

[0052] (3) Deposition of TiO2 layer: A TiO2 layer was deposited on the SiO2 layer by reactive magnetron sputtering. The oxygen flow rate and power were controlled to ensure that the thickness of each TiO2 layer was 25.74 nm and the refractive index reached 2.72.

[0053] (4) Multilayer stacking: SiO2 and TiO2 layers are deposited alternately and repeatedly to form the required 6-layer structure.

[0054] (5) Addition of graphene layer: The graphene layer is accurately aligned and placed on the interface of the periodic unit composed of SiO2 layer and TiO2 layer to ensure that light waves can be effectively refracted and reflected between the graphene layer and the dielectric layer.

[0055] (6) Device completion: The prepared multilayer structure can be finely processed by photolithography and etching technology to form the required device shape, and then the subsequent electrical contact and packaging processes are completed to finally obtain an ultraviolet light absorber with high absorption efficiency.

[0056] To further verify the reliability of the present invention and select the optimal solution, the inventors conducted a series of experiments, as follows:

[0057] 1. Fabrication of ultraviolet broadband light absorber structure

[0058] 1.1 Structural Composition of Ultraviolet Broadband Light Absorber

[0059] This invention proposes a broadband ultraviolet light absorber based on graphene and a multilayer periodic structure, and studies the absorption characteristics of this structure for ultraviolet light waves using the principle of distributed Bragg reflectors and the properties of graphene materials. The device structure, from top to bottom, consists of: a graphene layer, a distributed Bragg reflector grating structure layer (i.e., a SiO2 / TiO2 periodic layer), and a SiO2 substrate at the bottom. The overall structure can be represented as Gr / (SiO2 / TiO2). N / SiO2, where N is the number of periods. The distributed Bragg grating structure is composed of multiple stacked periodic units, with each periodic unit consisting of one layer of SiO2 and one layer of TiO2. A schematic diagram of the main structure of this device is shown below. Figure 1 As shown in the figure (① is the graphene layer; ② is the SiO2 layer; ③ is the TiO2 layer).

[0060] 1.2 Fabrication process of ultraviolet broadband light absorber

[0061] Fabrication process of ultraviolet broadband light absorbers based on graphene and multilayer periodic structures:

[0062] (1) Preparation of graphene layer: monolayer graphene was grown on copper substrate by chemical vapor deposition (CVD). The copper substrate was placed in a CVD reactor and methane was introduced to deposit graphene. After the growth was completed, a polymer film was used to transfer the graphene onto a pre-prepared SiO2 substrate.

[0063] (2) Deposition of SiO2 layer: After the graphene layer is transferred to the SiO2 substrate, SiO2 film is deposited by electron beam evaporation. The deposition time and power are adjusted to control the thickness of SiO2 and ensure that the thickness of each SiO2 layer is 48.26 nm.

[0064] (3) Deposition of TiO2 layer: A TiO2 layer was deposited on the SiO2 layer by reactive magnetron sputtering. The oxygen flow rate and power were controlled to ensure that the thickness of each TiO2 layer was 25.74 nm and the refractive index reached 2.72.

[0065] (4) Multilayer stacking: SiO2 and TiO2 are deposited alternately and repeatedly until the required total number of layers is formed.

[0066] (5) Addition of graphene layer: The graphene layer is accurately aligned and placed on the interface of the periodic unit composed of SiO2 layer and TiO2 layer to ensure that light waves can be effectively refracted and reflected between the graphene layer and the dielectric layer.

[0067] (6) Device completion: The prepared multilayer structure can be finely processed by photolithography and etching technology to form the required device shape, and then the subsequent electrical contact and packaging processes are completed to finally obtain an ultraviolet light absorber with high absorption efficiency.

[0068] 2. Optimization of ultraviolet broadband light absorber parameters

[0069] In this invention, the dielectric constant of the graphene model is described using the Lorentz-Drude model, which consists of two parts: the Lorentz model and the Drude model. The contributions of the two models differ in different wavelength ranges. In the ultraviolet range, the Lorentz model's contribution is dominant; in the infrared range, the Drude model's contribution is dominant. The dielectric constant is expressed as:

[0070]

[0071] In the formula and ε Drude These represent the Lorentz model and the Drude model, respectively, and their definitions are as follows:

[0072]

[0073] Where f is the oscillation intensity, Γ is the full width at half maximum (FWHM), E0 is the central energy, ρ is the resistivity, and τ is the scattering time.

[0074] The relationship between the refractive index parameter and dielectric constant of graphene is as follows:

[0075]

[0076] Where ε1 and ε2 are the real and imaginary parts of the dielectric constant, respectively, and n and k represent the real and imaginary parts of the refractive index, respectively.

[0077] To achieve high absorption in the ultraviolet band of the structure described in this invention, the device structure was simulated and optimized based on the finite-difference time-domain algorithm. Specifically, a three-dimensional model of the device was established in FDTD Solution software, using ultraviolet plane waves incident perpendicularly along the z-axis, periodic boundary conditions in the x and y directions, and perfectly matched boundary conditions in the z-direction, with a non-uniform mesh set to achieve good convergence results.

[0078] Electromagnetic waves propagating in a distributed Bragg reflector obey Maxwell's equations:

[0079]

[0080] In the formula, Let λ be the electric field vector of the electromagnetic wave, ω be the frequency of the electromagnetic wave, c be the speed of light in vacuum, ε0 be the vacuum permittivity, and ε(x) be the relative permittivity, which varies periodically with spatial position. This equation has solutions only at certain frequencies ω, and no solutions in other frequency regions. That is, light waves of certain frequencies are prohibited from passing through this structure and will be completely reflected, forming a photonic bandgap with a central wavelength of λ0. The refractive index n of the medium in the distributed Bragg reflector... H n Land dielectric layer thickness d H d L satisfy:

[0081]

[0082] The corresponding band gap width is:

[0083]

[0084] At the interface between the two media in a distributed Bragg reflector, light rays will be superimposed due to interference, forming reflected and transmitted light. Let M represent the relationship between the incident and emitted light in the distributed Bragg reflector; its essence is the product of the characteristic matrices of each layer of media material. j The characteristic matrix representing the j-th layer of the medium, with TE light as the incident light, is as follows:

[0085]

[0086] In the formula η j The optical admittance of the j-th dielectric layer can be expressed as:

[0087]

[0088] δ j The phase thickness can be expressed as:

[0089]

[0090] The transmission matrix M of the entire distributed Bragg reflector can then be expressed as:

[0091]

[0092] The relationship between the electromagnetic fields on both sides of the distributed Bragg reflector is as follows:

[0093]

[0094] A distributed Bragg reflector has a total of n dielectric thin films. Light waves passing through the entire distributed Bragg reflector must pass through N+1 dielectric interfaces. The first dielectric interface is the contact surface between air and the dielectric thin film, and its electromagnetic field distribution is as follows:

[0095]

[0096] The (N+1)th interface is the contact surface between the medium and the substrate, where the substrate can be air or other media, and its electromagnetic field distribution is as follows:

[0097]

[0098] In the formula ηs Let be the optical admittance of the substrate medium, in Siemens. From this, the reflection coefficient of the distributed Bragg reflector can be obtained as:

[0099]

[0100] The transmission coefficient is:

[0101]

[0102] Simultaneously, reflectivity R and transmittance T can be obtained:

[0103]

[0104] The formula for calculating the absorption rate A is thus obtained:

[0105] A = 1 - RT

[0106] The derivation of the band structure characteristics of TM waves in a distributed Bragg reflector is similar to that of TE waves; only the optical admittance of each dielectric film needs to be changed to:

[0107]

[0108] Based on the above analysis, we adopted λ0 = 280 nm as the incident wavelength and optimized the ultraviolet distributed Bragg reflector using 6 layers of SiO2 (each layer with a thickness of 48.26 nm) and 6 layers of TiO2 (each layer with a thickness of 25.74 nm). This resulted in a near-perfect reflection band in the ultraviolet range. The reflection spectrum of the distributed Bragg reflector in the ultraviolet range when the number of SiO2 / TiO2 periodic unit layers is 6 is shown below. Figure 2 As shown.

[0109] After optimizing the ultraviolet distributed Bragg reflector, a layer of graphene is placed on its surface. However, factors affecting the absorption characteristics of graphene include: the refractive index ratio of the dielectric layer, k(n). H / n L The invention focuses on four different dielectric materials: TiO2, Na3AlF6 (each Na3AlF6 layer is 52.63 nm thick), SiO2, and KCl (each KCl layer is 46.98 nm thick), with refractive indices of 2.72, 1.33, 1.45, and 1.49, respectively. These four dielectric materials are combined to form TiO2 / Na3AlF6, TiO2 / SiO2, and TiO2 / KCl, with refractive index ratios of k1 = 2.05, k2 = 1.88, and k3 = 1.83, respectively. The absorption spectra of the ultraviolet absorber under different dielectric layer refractive index ratios are shown below. Figure 3 As shown. By Figure 3It can be seen that as k gradually decreases from 2.05 to 1.83, the center wavelength λ0 of the absorption spectrum remains almost unchanged, while the bandwidth gradually decreases, from 129 nm to 105 nm. This indicates that when the refractive index of the material is different, the thickness will change accordingly, but the refractive index ratio of the two dielectric films does not affect the center wavelength of the absorption spectrum. The larger the refractive index ratio, the stronger the reflection of the distributed Bragg reflector, the wider the bandwidth of the absorption spectrum, the steeper the edge of the absorption band, and the better the cutoff. In actual fabrication, even if there is a certain deviation between the dielectric layer thickness and λ0, a wide ultraviolet band with almost complete absorption can still be generated according to the formula. Within this wide ultraviolet band, almost all light transmission is absorbed.

[0110] The composite structure designed in this invention fully utilizes the unique properties of photonic crystals through the periodic superposition of graphene and multilayer dielectric materials. This invention also provides a detailed analysis of the sensitivity of the absorption spectrum of this structure to the polarization of incident light. The absorption spectra of the ultraviolet absorber under different polarization states of incident light are shown below. Figure 4 As shown, when the polarization state of the incident light changes from s-polarization to p-polarization, the absorption efficiency of the light in this structure remains almost unchanged, demonstrating broad adaptability to different polarizations. This characteristic mainly stems from the symmetry and periodic arrangement of the structure, where the alternating layout of graphene layers and dielectric layers ensures that the relationship between light absorption and polarization direction no longer affects the absorption effect. Furthermore, the interface effect of the graphene layers further enhances the light absorption capability of this structure, enabling it to maintain efficient light absorption characteristics under different polarization states. Therefore, this structure exhibits excellent polarization insensitivity and is suitable for efficient absorption from various light sources and polarization states.

[0111] Considering practical applications, this invention selects SiO2 as the raw material due to its high stability, low cost, and convenient processing. After optimization, the optimal parameters of this structure were determined to be: a graphene thickness of 0.34 nm; a refractive index of 1.45 and a thickness of 48.26 nm for each SiO2 dielectric layer; and a refractive index of 2.72 and a thickness of 25.74 nm for each TiO2 dielectric layer.

[0112] Furthermore, this invention measured the light absorption performance of the device under normal incidence θ = 0° and with 2, 4, 6, and 8 SiO2 / TiO2 periodic layers. The absorption spectra of the ultraviolet absorber under normal incidence conditions with different numbers of SiO2 / TiO2 periodic unit layers are shown below. Figure 5As shown in the figure, when the number of periods is 2, the absorption spectrum exhibits a significant oscillation effect in the ultraviolet band, with an absorption efficiency below 90%. As the number of periods increases, the oscillation effect weakens. When the number of periods reaches 6, the absorption spectrum tends to stabilize, exhibiting high absorption efficiency in the wavelength range of 240–370 nm, with an absorption peak value as high as 99.75% and a full width at half maximum (FWHM) of 115 nm. This is because when the number of periods is small, the wavelength fluctuations reflected by the distributed Bragg reflector are large, and the reflectivity is very low (35%–55%). The interference effect formed by the incident wave in the graphene layer is weak and unstable, resulting in strong oscillations in the absorption spectrum. As the number of periods increases, in the ultraviolet range, the light waves in the multilayer structure undergo more reflections and superpositions, and the reflectivity of the distributed Bragg reflector gradually stabilizes and approaches 100%. When the incident light wave satisfies the distributed Bragg reflection condition, the interference effect is enhanced, confining the light field to the graphene layer and the periodic structure, thereby enhancing the absorption of graphene and making the absorption curve more stable.

[0113] For optical absorbers, the angle response of incident light is also crucial. Therefore, the research team conducted simulation analysis of the light absorption characteristics of the device under different incident angles. The absorption spectra of the ultraviolet absorber under different incident light angles are shown below. Figure 6 As shown in the figure, the absorption spectrum exhibits an overall rightward shift (blue shift of the absorption peak) with increasing incident angle, and the full width at half maximum (FWHM) of the absorption line decreases. At an incident angle of 30°, the absorption peak value remains as high as 98.66%, but the FWHM of the absorption line decreases to 89 nm. Therefore, the ultraviolet absorber designed in this invention possesses good angle response characteristics and can achieve efficient light absorption over a wide range of incident angles.

[0114] This invention uses numerical methods to study the absorption characteristics of a graphene-integrated distributed Bragg grating structure in the ultraviolet (UV) band. The results demonstrate that this structure can achieve broadband, large-angle, and high-efficiency light absorption in the UV band, solving the problems of low absorption rate, narrow bandwidth, and sensitivity to polarized light in the UV band associated with traditional single-layer graphene. This invention provides an important reference for the design of high-efficiency UV absorbers.

[0115] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A graphene and multilayer periodic structure based ultraviolet broadband light absorber, characterized by, The absorber is sequentially composed of a graphene layer, a distributed Bragg reflection grating structure layer and a SiO2 substrate from top to bottom, wherein: The thickness of the graphene layer is 0.34 nm; The distributed Bragg reflection grating structure layer is composed of a stack of periodic units composed of SiO2 and TiO2, and the number of periodic unit layers is 6; the thickness of the SiO2 layer is 48.26 nm, and the refractive index is 1.45; the thickness of the TiO2 layer is 25.74 nm, and the refractive index is 2.

72.

2. The method of claim 1, wherein the method is performed by the following steps: (a) preparing a graphene layer on a substrate; (b) depositing a first metal layer on the graphene layer; (c) depositing a second metal layer on the first metal layer; and (d) depositing a third metal layer on the second metal layer. The method comprises the following steps: S1. Preparation of the graphene layer: A graphene layer with a thickness of 0.34 nm is grown on a copper substrate by chemical vapor deposition; the copper substrate is placed in a chemical vapor deposition reaction furnace, and methane is introduced for graphene deposition; after the growth is completed, the graphene is transferred to a pre-prepared SiO2 substrate using a polymer film; S2. Deposition of the SiO2 layer: After the graphene layer is transferred to the SiO2 substrate, a SiO2 film is deposited by electron beam evaporation; the deposition time and power are adjusted to ensure that the thickness of each SiO2 layer is 48.26 nm and the refractive index reaches 1.45; S3. Deposition of the TiO2 layer: A TiO2 layer is deposited on the SiO2 layer by reactive magnetron sputtering; the oxygen flow rate and power are controlled to ensure that the thickness of the TiO2 layer is 25.74 nm and the refractive index reaches 2.72; S4. Multilayer stacking: The SiO2 layer and the TiO2 layer are repeatedly deposited alternately until the total number of layers reaches 6; S5. Addition of the graphene layer: The graphene layer is accurately aligned and placed on the interface of the periodic unit composed of the SiO2 layer and the TiO2 layer; S6. Device completion: The multilayer structure is finely processed by photolithography and etching technology, and subsequent electrical contact and packaging processes are completed, and the device is obtained.

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