Graphical nanogold array modification-based graphene plasmon polarizer and application
By preparing patterned nanogold arrays on the graphene surface, the light absorption polarization characteristics of graphene are regulated, and the problem of insufficient light absorption and band selectivity of graphene is solved, and efficient light absorption and polarization response are achieved.
Patent Information
- Application Number
- CN202411711021.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-27
- Publication Date
- 2025-03-07
AI Technical Summary
The existing graphene materials have low absolute absorption rate of light and are not selective to the band of light, making it difficult to effectively regulate the polarization characteristics of photonic devices.
By preparing a patterned nanogold array, including nested asymmetric gold cylinders and gold rings, on the surface of graphene, a local surface plasmon is formed to regulate the polarization characteristics of light absorption.
The light absorption rate and detection efficiency of graphene are significantly enhanced, and the sensitive response to different polarized lights is achieved, and the structure is simple and easy to integrate.
Smart Images
Figure CN119575524A_ABST
Abstract
Description
Methodology Area
[0001] The present invention relates to the field of optical communication technology, and in particular to a graphene plasmon polarizer modified based on a patterned nano-gold array and its application. Background Methods
[0002] Two-dimensional materials refer to materials in which electrons can only move freely on a non-nanoscale (1-100nm) in two dimensions, among which graphene is a typical two-dimensional material. Graphene is a two-dimensional material in which a single layer of carbon atoms is arranged in a honeycomb structure. It has attracted widespread attention from researchers around the world because of its excellent properties in optics, electricity, heat, mechanics and many other aspects. Graphene is only 0.33nm thick, but has a strong interaction with light. Undoped graphene has a consistent response from near-infrared to visible light, does not have a unique response in a certain band, and has an absorption rate of about 2.3% for vertically incident light. At present, graphene has problems such as low absolute absorption rate of light and lack of selectivity for light bands.
[0003] Localized surface plasmon (LSP) is an electron group resonance effect that occurs at the interface of metal nanostructures and semiconductors. It can overcome the traditional light diffraction limit and enhance the local field, but the inherent dielectric properties of metals are difficult to achieve in-situ regulation through conductivity and other methods. Therefore, it is urgent to develop a new type of photonic device that can reasonably utilize the in-situ regulation ability of polarized light. Summary of the invention
[0004] In order to solve the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a graphene plasmon polarizer modified by a patterned gold nanoparticle array and its application to regulate the polarization characteristics of light absorption in photonic devices.
[0005] The technical solution of the present invention to solve the above technical problems is as follows: a graphene plasmon polarizer modified by a patterned nanogold array is provided, comprising a substrate, a light absorption layer, a patterned metal array and a top electrode; the substrate is silicon dioxide; the light absorption layer is graphene; the patterned metal array is nested asymmetric gold cylinders and gold rings; the top electrode is a source electrode and a drain electrode; wherein the source electrode and the drain electrode are both gold electrodes.
[0006] Furthermore, the period of the patterned gold nanoparticle array is 160-250 nm and the height is 30-80 nm.
[0007] Furthermore, the radius of the gold cylinder is 15-40 nm; the inner radius of the gold ring is 45-50 nm, and the outer radius is 65-80 nm.
[0008] Furthermore, the gold cylinder is offset from the center of the gold ring by 0-25 nm.
[0009] Furthermore, the graphene is a single layer of graphene of 80-120 mm2.
[0010] The invention provides a method for preparing a graphene plasmon polarizer modified by a patterned nano-gold array, comprising the following steps: transferring a single-layer graphene on a silicon wafer covered with silicon dioxide, and preparing a gold nano-array on the graphene by photolithography and sputtering processes.
[0011] The present invention provides an application of a graphene plasmon polarizer modified by a patterned nano-gold array in the preparation of a photoelectric detector.
[0012] The present invention also provides a photoelectric detector, comprising the above-mentioned graphene plasmon polarizer.
[0013] The present invention has the following beneficial effects:
[0014] (1) The present invention utilizes gold nanoarrays to excite localized plasmons on the graphene surface, which greatly enhances the local electric field on the graphene surface, increases the generation rate of electron-hole pairs in graphene and the light absorption rate of graphene, thereby improving the detection efficiency of the plasmon polarizer.
[0015] (2) The graphene plasmon polarizer of the present invention has the property of being sensitive to the polarization of absorbed light, and the polarization property of the light absorption of the device can be regulated by the asymmetry and size of the nested gold rings and gold cylinders. By utilizing the resonant cavity formed by the nested gold nanocylinders and gold nanorings and the surface plasmon resonance effect, a large-area two-dimensional material plasmon polarizer structure capable of regulating the absorption band of the plasmon polarizer is obtained. By changing the relative positions of the gold nanorings and gold nanocylinders to change the shape of the resonant cavity, a nanostructure with different resonant cavity sizes in each direction is formed, so that the plasmon polarizer of the present invention is sensitive to light of different polarizations.
[0016] (3) The graphene plasmon polarizer of the present invention is universal, has a simple structure, is easy to integrate, is suitable for large-area preparation of photodetectors, and has a simple process flow.
[0017] More specifically, the thickness of the gold nanoarray is 50 nm, the radius of the gold cylinder in the gold nanoarray is 25 nm, the inner radius of the gold ring is 50 nm, and the outer radius is 75 nm. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a schematic diagram of the three-dimensional structure of the simulation device, and a schematic diagram of the top view;
[0019] Figure 2is a curve showing the change of the absorbance of the polarizers of Comparative Examples 1-2 and Example 1 with the light wavelength band under 0° polarized light irradiation;
[0020] Figure 3 : is the electric field distribution diagram of the polarizer of Example 1 at 819nm and 1119nm under 0° polarized light irradiation;
[0021] Figure 4 is a graph showing the change in light absorption curve of the polarizer of Example 1 at 0-90° polarized light within the light wavelength range of 400-1200nm;
[0022] Figure 5 is a graph showing the change in light absorption curve of the polarizer of Example 1 with respect to the position of different gold nano-cylinders in the gold nano-array under 0° polarized light irradiation;
[0023] Figure 6 This is a graph showing the change in the light absorption curve of the polarizer of Example 1 due to the outer radius of different gold nanorings in the gold nanoarray. DETAILED DESCRIPTION
[0024] The following examples are only used to explain the present invention and are not intended to limit the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.
[0025] Example 1
[0026] A graphene plasmon polarizer based on patterned nano-gold array modification includes a substrate, a light absorption layer, a patterned metal array and a top electrode; the substrate is silicon dioxide; the light absorption layer is graphene; the patterned metal array is nested asymmetric gold cylinders and gold rings; the top electrode is a source electrode and a drain electrode, wherein the source electrode and the drain electrode are both gold electrodes, and its three-dimensional structure diagram and top view schematic diagram are shown in FIG. Figure 1 As shown. Figure 1 It can be seen that the graphene plasmon polarizer is composed of gold nanoarray, graphene and silicon dioxide from top to bottom; Figure 1 A is the shape of the nested gold cylinder and gold ring as shown in the gold nanoarray. The diameter of the nanogold cylinder is 50nm; the inner diameter of the nanogold ring is 100nm, and the outer diameter is 150nm; the height of the gold nanoarray is 50nm, the period of the patterned nanogold array is 200nm, and the gold cylinder is offset from the center of the gold ring by 15nm; wherein the graphene is a single-layer graphene of 100mm2. Its preparation method includes the following steps: transferring a single-layer graphene on a silicon wafer covered with silicon dioxide, and preparing a gold nanoarray on the graphene by photolithography and sputtering processes. Sputtering gold source and drain electrodes in the same way, the source and drain electrodes are respectively located on both sides of the gold nanoarray.
[0027] Comparative Example 1
[0028] A graphene plasmon polarizer includes a substrate, a light absorbing layer and a top electrode; the substrate is silicon dioxide; the light absorbing layer is graphene; the top electrode is a source electrode and a drain electrode, wherein the source electrode and the drain electrode are both gold electrodes. The device is prepared in the same manner as in Example 1, except that the sputtering process of the nano-gold structure is missing.
[0029] Comparative Example 2
[0030] A plasmon polarizer modified by a patterned nano-gold array includes a substrate, a patterned metal array, and a top electrode; the substrate is silicon dioxide; the patterned metal array is a nested asymmetric gold cylinder and a gold ring; the top electrode is a source electrode and a drain electrode, wherein the source electrode and the drain electrode are both gold electrodes. The device is prepared in the same manner as in Example 1, except that the sputtering process of graphene is missing.
[0031] Test example
[0032] In the simulation using the finite-difference time-domain method (FDTD), the simulation area is 200 nm in length and width; a cuboid with the above area as the center and a height of 600 nm is used as the simulation area, the length and width boundaries are set as periodic boundary conditions, and the top and bottom boundary conditions are set as perfectly matched layers (PML), which will absorb all electromagnetic waves.
[0033] (1) Under the condition of fixing the simulation grid size to 1.5*1.5*2.5nm, the simulation band was selected to be 400-1200nm, and the light absorption curves of the polarizers of Comparative Examples 1-2 and Example 1 under 0° polarized light were respectively measured. The results are shown in FIG. Figure 2 As shown, the polarizer of Example 1 has two absorption peaks at 400-1200 nm. This is because the special structure of the gold nanoarray determines that the device can detect light of different wavelengths.
[0034] (2) Figure 3 is the electric field distribution diagram of the polarizer of Example 1 at two absorption peak positions under 0° polarized light irradiation, where Figure 3 The figure on the right shows the electric field distribution in the 819nm band. The electric field on the graphene surface is greatly enhanced at the slit where the nano-cylinder and the nano-ring contact. The figure on the right shows the electric field distribution in the 1119nm band. The electric field on the graphene surface is greatly enhanced at the edge of the gold nano-cylinder. The special structure of the gold nano-array forms a resonant cavity, which resonates with light of a specific wavelength. The interaction of graphene light is enhanced and the absorption is increased. In the simulation, the size of the simulation area, source, and monitor should be set accordingly. The size of the source and monitor is set to 400nm*400nm.
[0035] (3) The polarization characteristics of the polarizer of Example 1 are simulated. The polarization angle of polarized light is 0-90°. The simulation is performed every 10° to obtain the trend of light absorption of the polarizer of Example 1 changing with the polarization angle. Figure 4 It can be seen that in the 819nm and 1119nm bands, the light absorption of the polarizer of Example 1 decreases as the polarization direction changes from 0° to 90°, and the absorption peak at 1119nm shifts to 900nm. In the 684nm band, the light absorption rate of the polarizer of Example 1 increases as the polarization direction changes from 0° to 90°.
[0036] (4) Under 0° polarized light irradiation, the positions of the gold nanocolumns were offset from the center of the ring by 0nm, 5nm, 10nm, 15nm, 20nm and 25nm, respectively, to detect the effect of the positions of different gold nanocolumns in the gold nanoarray on the light absorption rate of the polarizer of Example 1. Figure 5 It can be seen that when the gold nanocylinder is offset by 25nm from the center of the ring, the absorption curve is significantly different, and the absorption rate is improved, and the light absorption rate exceeds 0.4 at a wavelength of 1119nm. When the offset distance is not 25nm, the absorption curve is similar to the absorption curve with a polarization angle of 90°, which proves that the obvious polarization characteristics only appear when the gold nanocylinder is offset by 25nm from the center of the ring.
[0037] (5) Under 0° polarized light irradiation, the outer radius of the gold nanorings was changed to 65 nm, 70 nm, and 75 nm, respectively, to detect the effect of the outer radius of the gold nanorings in the gold nanoarray on the light absorption rate of the polarizer of Example 1. Figure 6 It can be seen that as the outer radius of the gold nanoring increases, the absorption peak of the polarizer of Example 1 increases at 800nm, and the light absorption rate increases from 0.23 to 0.34; in the wavelength range of 1000-1200nm, the absorption peak of the polarizer of Example 1 gradually shifts to the right, and the light absorption rate increases to 0.4.
[0038] From the above results, it can be seen that the present invention can excite local surface plasmons by modifying graphene with gold nanoarrays, thereby enhancing the absorption of light by graphene. Compared with the methods of contrast band engineering, heterostructure construction, surface interface regulation, etc., the method provided by the present invention is simple in structure and easy to control. At the same time, the asymmetry of the gold nanoarray enables the graphene plasmon polarizer of the present invention to produce different responses to polarized light in different directions, providing a feasible method for the graphene plasmon polarizer to detect polarized light.
[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A graphene plasmon polarizer modified by a patterned gold nanoparticle array, characterized in that: It includes a substrate, a light absorption layer, a patterned metal array and a top electrode; the substrate is silicon dioxide; the light absorption layer is graphene; the patterned metal array is nested asymmetric gold cylinders and gold rings; the top electrode is a source electrode and a drain electrode; wherein the source electrode and the drain electrode are both gold electrodes.
2. The graphene plasmon polarizer based on patterned gold nanoparticle array modification according to claim 1, characterized in that: The length (period) of each unit of the patterned nanogold array is 160-250 nm, and the height is 30-80 nm.
3. The graphene plasmon polarizer based on patterned gold nanoparticle array modification according to claim 1, characterized in that: The radius of the gold cylinder is 15-40nm; the inner radius of the gold ring is 45-50nm, and the outer radius is 65-80nm.
4. The graphene plasmon polarizer based on patterned gold nanoparticle array modification according to claim 1 or 3, characterized in that: The gold cylinder is offset from the center of the gold ring by 0-25 nm.
5. The graphene plasmon polarizer based on patterned gold nanoarray modification according to claim 1, characterized in that: The graphene is a single-layer graphene of 80-120 mm2.
6. The method for preparing a graphene plasmon polarizer modified by a patterned gold nanoparticle array according to claim 1, characterized in that: The following steps are involved: A single layer of graphene is transferred onto a silicon wafer covered with silicon dioxide, and a gold nanoarray is prepared on the graphene by photolithography and sputtering. Gold source and drain electrodes are sputtered in the same way, and the source and drain electrodes are located on both sides of the gold nanoarray.
7. Use of the graphene plasmon polarizer modified by patterned gold nanoparticle array according to any one of claims 1 to 5 in the preparation of a photodetector.
8. A photoelectric detector, characterized in that: Comprising the graphene plasmon polarizer according to claim 1.