An optical structure for achieving efficient dual-channel light absorption based on graphene

Abstract

The present invention discloses an optical structure for realizing dual-channel high-efficiency light absorption based on graphene, which includes a metal grating, a dielectric layer, and graphene nanoribbons. The metal grating has grooves, the dielectric layer is filled with a dielectric, the dielectric layer is located in the grooves, there are a first cavity and a second cavity between the dielectric layer and the metal grating, the first cavity and the second cavity are oppositely arranged with the dielectric layer as the center, and the number of the graphene nanoribbons is two, which are respectively located on the first cavity and the second cavity. By partially filling the grooves of the metal grating with a dielectric, the graphene nanoribbons laid above interact with the metal grating, the first cavity, and the second cavity respectively, jointly exciting the surface plasmon resonance of graphene to achieve enhanced dual-channel high-efficiency light absorption.

Description

Technical Field

[0001] The present invention relates to the technical fields of photoelectric detection, solar thermal conversion and electromagnetic absorption, and in particular to an optical structure based on graphene for realizing dual-channel efficient light absorption. Background Art

[0002] The absorption efficiency of optoelectronic materials greatly affects the performance of optoelectronic devices in the fields of optoelectronic regulation and photothermal conversion. These devices realize their functions by converting the absorbed light into electrical energy or thermal energy through optoelectronic materials. Generally speaking, the higher the absorption efficiency of optoelectronic materials, the better the overall performance of optoelectronic devices. Therefore, in order to further improve the performance of optoelectronic devices, improving the absorption efficiency of optoelectronic materials has become a hot topic for researchers.

[0003] In general, most of the existing graphene-based devices for improving light absorption efficiency work in the mid-infrared or far-infrared bands, and there are fewer studies on light absorption devices that can be applied to the visible light-near-infrared band. In addition, the achieved absorption bandwidth is narrow, and wavelength changes within a very small range will cause a large change in the absorption efficiency, which is not conducive to the practical application of the device in the fields of photoelectric detection, solar thermal conversion, etc. Summary of the invention

[0004] The purpose of the present invention is to provide an optical structure based on graphene to achieve dual-channel efficient light absorption, aiming to solve the problem that there are few studies on light absorption devices applied to the visible light-near infrared band, and the absorption bandwidth achieved is narrow. The wavelength change in a very small range will cause a large change in the absorption efficiency, which is not conducive to the practical application of the device in the fields of photoelectric detection, solar thermal conversion, etc.

[0005] To achieve the above-mentioned purpose, the present invention provides an optical structure for realizing dual-channel efficient light absorption based on graphene, comprising a metal grating, a dielectric layer and a graphene nanoribbon, wherein the metal grating has a groove, the dielectric layer is filled with a medium, the dielectric layer is located in the groove, a first cavity and a second cavity are provided between the dielectric layer and the metal grating, the first cavity and the second cavity are arranged relative to each other with the dielectric layer as the center, and the number of the graphene nanoribbons is two, which are respectively located on the first cavity and the second cavity.

[0006] Wherein, the width of the dielectric layer is 65nm-85nm.

[0007] Wherein, the width of the graphene nanoribbon is 20nm to 35nm.

[0008] Wherein, the width of the dielectric layer is 80 nm, and the width of the graphene nanoribbon is 25 nm.

[0009] Wherein, the height of the groove is equal to twice the width of the dielectric layer.

[0010] Wherein, the thickness from the metal grating to the bottom of the groove is 2um.

[0011] There are multiple grooves, and the grooves are evenly distributed on the metal grating in an array.

[0012] Wherein, the metal grating is one of gold, silver, chromium or aluminum.

[0013] The optical structure of the present invention based on graphene for realizing dual-channel efficient light absorption is characterized in that the metal grating has a groove, the dielectric layer is filled with a medium, the dielectric layer is located in the groove, a first cavity and a second cavity are provided between the dielectric layer and the metal grating, the first cavity and the second cavity are arranged relatively with the dielectric layer as the center, and the number of the graphene nanoribbons is two, which are respectively located on the first cavity and the second cavity. By partially filling the groove of the metal grating with a medium, the graphene nanoribbons laid on the top interact with the metal grating and the first cavity and the second cavity respectively, and jointly excite the graphene surface plasma resonance, thereby realizing dual-channel efficient light absorption enhancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a schematic diagram of the structure of an optical structure for realizing dual-channel efficient light absorption based on graphene according to the present invention;

[0016] Figure 2 It is a schematic diagram of the structure of the metal grating and graphene nanoribbon of the present invention;

[0017] Figure 3 It is the absorption spectrum diagram of the structure with and without graphene nanoribbons in the present invention;

[0018] Figure 4 This is a structural absorption spectrum diagram of changing the width of the filling medium in the present invention;

[0019] Figure 5 This is a structural absorption spectrum diagram of changing the width of graphene nanoribbons in the present invention;

[0020] Figure 6 The electric field distribution diagram of the resonance position under the optimal structural parameters of the present invention;

[0021] In the figure: 100-optical structure for realizing dual-channel efficient light absorption based on graphene, 1-metal grating, 2-dielectric layer, 3-graphene nanoribbon, 4-rotating component, 11-groove, 12-first cavity, 13-second cavity, 41-fixed part, 42-sliding part, 43-first connecting part, 44-second connecting part, 45-driving part. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0024] See also Figure 2 The present invention provides an optical structure 100 for realizing dual-channel efficient light absorption based on graphene, comprising a metal grating 1, a dielectric layer 2 and a graphene nanoribbon 3, wherein the metal grating 1 has a groove 11, the dielectric layer 2 is filled with a dielectric, the dielectric layer 2 is located in the groove 11, a first cavity 12 and a second cavity 13 are provided between the dielectric layer 2 and the metal grating 1, the first cavity 12 and the second cavity 13 are arranged relative to each other with the dielectric layer 2 as the center, and the number of the graphene nanoribbons 3 is two, which are respectively located on the first cavity 12 and the second cavity 13.

[0025] In this embodiment, the metal grating 1 is one of gold, silver, chromium or aluminum. The medium is one of silicon dioxide, magnesium oxide, magnesium difluoride or titanium dioxide. The metal grating 1 has a groove 11, and the number of the grooves 11 is multiple, and the multiple grooves 11 are evenly distributed on the metal grating 1 in an array manner. The groove 11 is a rectangular metal groove, and the metal surface plasma resonance is excited by the rectangular metal groove array structure, thereby enhancing the interaction with the graphene nanoribbon 3, further exciting the graphene surface plasma resonance, and achieving the effect of enhancing graphene absorption. The height h2 of the groove 11 is equal to twice the width w1 of the dielectric layer 2. The thickness h1 from the metal grating 1 to the bottom of the groove 11 is 2um, which is greater than the skin depth of the metal material in the visible light-near infrared band, so there is no transmitted light.

[0026] The graphene nanoribbon 3 serves as an absorption layer to absorb incident light of the corresponding wavelength band. The first cavity 12 and the second cavity 13 are provided between the metal grating 1 and the dielectric layer 2 to excite graphene surface plasmon resonance. In the first cavity 12, the metal surface plasmon resonance is excited by the metal grating 1, and interacts with the graphene nanoribbon 3 above the first cavity 12, thereby exciting the graphene surface plasmon resonance in the visible light band; in the second cavity 13, the graphene nanoribbon 3 can be regarded as a quantum dot placed in the cavity. When the width of the graphene nanoribbon 3 and the frequency of the incident light reach the excitation condition, the graphene nanoribbon 3 is excited in the near-infrared band to produce a local field enhancement effect, thereby generating a resonance absorption peak. By adjusting the medium filled in the dielectric layer 2 and the width of the graphene nanoribbon 3, the two resonance couplings are made more intense, and finally dual-channel efficient light absorption in the visible light-near infrared band is achieved. The array period of the metal grating 1 is 200 nm, the Fermi level of graphene is 0.5 eV, the width w1 of the dielectric layer 2 is 65 nm to 85 nm, and the width w2 of the graphene nanoribbon 3 is 20 nm to 35 nm.

[0027] like Figure 4 As shown, Figure 4 This is the structural absorption spectrum of the structure with the width of the filling medium changed. Figure 4 It can be seen that as the medium width w1 increases from 65nm to 85nm, the resonance peak position moves along the long wavelength direction, that is, it redshifts, the absorption efficiency of the left peak gradually decreases, and the absorption efficiency of the right peak gradually increases. When the medium width w1 is 80nm, the peak difference between the left and right peaks is the smallest, and the overall absorption efficiency of the structure is the highest.

[0028] like Figure 5 As shown, Figure 5 is a structural absorption spectrum diagram of changing the width of the graphene nanoribbon 3 in the structure. Figure 5 It can be seen that when the width w2 of the graphene nanoribbon 3 increases from 20nm to 35nm, the absorption efficiency of the left peak gradually increases from 70% to 100%, and the resonance peak position hardly changes, while the absorption efficiency of the right peak gradually decreases from 95% to 40%, and the resonance peak position undergoes a large red shift. When the width w2 of the graphene nanoribbon 3 is 25nm, the peak difference between the left and right peaks is the smallest, and the overall absorption efficiency of the structure is the highest. Therefore, when the width w1 of the dielectric layer 2 is 80nm and the width w2 of the graphene nanoribbon 3 is 25nm, the overall absorption efficiency of the structure is the highest, which is the optimal structural parameter.

[0029] Analyze the electric field distribution diagram at the resonance position under the optimal structural parameters, such as Figure 6 As shown, Figure 6 is a unit structure in the selected metal grating 1 array, and the chromaticity bar represents the magnitude of the electric field intensity. Figure 6 It can be seen that the electric field in the first cavity 12 is greatly enhanced on the upper surface of the graphene, and the electric field at the end in contact with the metal is strongly coupled, which is a typical feature of metal surface plasmon resonance. In the second cavity 13, the energy is mainly concentrated above the second cavity 13. It can be seen that the graphene nanoribbon 3, as a quantum dot in the second cavity 13, stimulates the local field enhancement effect of the right cavity.

[0030] from Figure 3 It can be seen that in the absence of graphene, due to the high reflectivity of metal, most of the incident light is reflected, resulting in a very low absorption rate of the entire structure. However, after adding the graphene nanostrip 3, the metal grating 1 and the cavity interact with the graphene nanostrip 3 respectively, jointly exciting the graphene surface plasma resonance, and enhancing the field localization effect of graphene. More than 80% of light absorption is achieved in the range of 740-820nm, and more than 90% of light absorption is achieved in the range of 1450-1715nm. The maximum light absorption efficiency reaches nearly 100%, realizing dual-channel high-efficiency light absorption enhancement in the visible light-near infrared band.

[0031] The optical structure 100 for realizing dual-channel efficient light absorption based on graphene excites the graphene surface plasma resonance through the metal grating 1 and the first cavity 12 and the second cavity 13 of the subwavelength structure, thereby realizing dual-channel efficient light absorption in the visible light-near infrared band. Based on the determination of the size parameters of the metal grating 1, the structure can adjust the intensity of the graphene surface plasma resonance excited by the metal grating 1 and the first cavity 12 and the second cavity 13 by adjusting the filling medium and the width of the graphene nanoribbon 3, forming an electric field localization in a wider band range and making the light field energy mainly distributed near the graphene nanoribbon 3, thereby effectively enhancing the absorption efficiency of light in a wider band range. Therefore, the present invention has great application value in the fields of photoelectric detection, solar thermal conversion and electromagnetic absorption in the visible light-near infrared band.

[0032] Furthermore, the optical structure 100 for achieving dual-channel efficient light absorption based on graphene also includes a rotating component 4, the number of the rotating components 4 is two, and the two rotating components 4 are located on both sides of the metal grating 1. The rotating component 4 includes a fixed member 41, a sliding member 42, a first connecting member 43, a second connecting member 44 and a driving member 45. The fixed member 41 is fixedly connected to the metal grating 1 and is located on one side of the metal grating 1. The sliding member 42 is slidably connected to the fixed member 41, the first connecting member 43 is rotatably connected to the sliding member 42, the second connecting member 44 is rotatably connected to the first connecting member 43 and the sliding member 42, the sliding member 42, the first connecting member 43 and the second connecting member 44 are located on the same plane, and are on two planes with the metal grating 1, and the output end of the driving member 45 is transmission-connected to the first connecting member 43.

[0033] In this implementation, see Figure 1 The driving member 45 is a cylinder, and the output end of the cylinder is transmission-connected with the first connecting member 43. The piston rod of the cylinder moves and extends under the action of air pressure, driving the first connecting member 43 to move in one direction. The second connecting member 44 and the sliding member 42 are both rotationally connected to the first connecting member 43, thereby driving the sliding member 42 to slide in the direction where the fixing member 41 is away from the cylinder, thereby driving the fixing member 41 to flip to the side away from the cylinder. The metal grating 1 is fixedly connected to the fixing member 41, thereby driving the metal grating 1 to flip, thereby realizing multi-angle reception of light for absorption and enhancing the absorption effect.

[0034] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. An optical structure for realizing dual-channel high-efficiency light absorption based on graphene, characterized in that, it includes a metal grating, a dielectric layer and graphene nanoribbons. The metal grating has grooves, the dielectric layer is filled with a dielectric, the dielectric layer is located in the grooves, there are a first cavity and a second cavity between the dielectric layer and the metal grating, the first cavity and the second cavity are oppositely arranged with the dielectric layer as the center, and the number of the graphene nanoribbons is two, which are respectively located on the first cavity and the second cavity; the period of the metal grating array is 200 nm, and the Fermi level of graphene is 0.5 eV; the width of the dielectric layer is 65 nm to 85 nm; the width of the graphene nanoribbons is 20 nm to 35 nm; after adding the graphene nanoribbons, the metal grating and the cavities interact with the graphene nanoribbons respectively, jointly exciting the surface plasmon resonance of graphene and enhancing the field localization effect of graphene; the light absorption reaches more than 80% in the range of 740 - 820 nm, reaches more than 90% in the range of 1450 - 1715 nm, and the maximum light absorption efficiency reaches nearly 100%, realizing dual-channel high-efficiency light absorption enhancement in the visible - near-infrared band.

2. The optical structure for realizing dual-channel high-efficiency light absorption based on graphene according to claim 1, characterized in that, the width of the dielectric layer is 80 nm, and the width of the graphene nanoribbons is 25 nm.

3. The optical structure for realizing dual-channel high-efficiency light absorption based on graphene according to claim 1, characterized in that, the height of the grooves is equal to twice the width of the dielectric layer.

4. The optical structure for realizing dual-channel high-efficiency light absorption based on graphene according to claim 3, characterized in that, the thickness from the metal grating to the bottom of the grooves is 2 μm.

5. The optical structure for realizing dual-channel high-efficiency light absorption based on graphene according to claim 4, characterized in that, the number of the grooves is multiple, and the multiple grooves are uniformly distributed on the metal grating in an array manner.

6. The optical structure for realizing dual-channel high-efficiency light absorption based on graphene according to claim 1, characterized in that, the metal grating is one of gold, silver, chromium or aluminum.

7. The optical structure for realizing dual-channel high-efficiency light absorption based on graphene according to claim 6, characterized in that, the dielectric is one of silica, magnesium oxide, magnesium difluoride or titanium dioxide.

8. The optical structure for realizing dual-channel high-efficiency light absorption based on graphene according to claim 1, characterized in that, The optical structure for realizing dual-channel high-efficiency light absorption based on graphene further includes a rotation assembly. The number of the rotation assemblies is two. The two rotation assemblies are located on both sides of the metal grating. The rotation assembly includes a fixing member, a sliding member, a first connecting member, a second connecting member, and a driving member. The fixing member is fixedly connected to the metal grating and is located on one side of the metal grating. The sliding member is slidably connected to the fixing member. The first connecting member is rotatably connected to the sliding member. The second connecting member is rotatably connected to the first connecting member and the sliding member. The sliding member, the first connecting member, and the second connecting member are in the same plane and are in two planes with the metal grating. The output end of the driving member is drivingly connected to the first connecting member.

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