| Graphene is a two-dimensional crystalline material made up of a single layer of carbon atoms,whose structure resembles a honeycomb grid.It has excellent electrical,chemical and thermal properties,such as high carrier mobility,large surface area and high thermal conductivity.Compared with single-layer graphene,three-dimensional graphene has a larger thickness and porous structure.It not only has excellent electrical and chemical properties of graphene,but also has unique optical properties,which makes it have a huge application prospect in a variety of fields,such as energy storage and sensing.Laser-induced graphene(LIG)is a method to directly prepare patterned three-dimensional porous graphene on the surface of polyimide(PI)by laser.Compared with traditional chemical vapor deposition and hydrothermal methods,this method is simple and inexpensive.By controlling laser parameters,not only can the optical and electrical properties of graphene be controlled,but also arbitrary patterns can be customized,which can be applied to the production of various microstructure devices.Based on this method,THz metamaterial filter,microwave metamaterial wideband absorber and structure color are designed and prepared respectively,and their applications are studied.The main research content is summarized as follows:1.A THz metamaterial filter is designed and fabricated based on LIG technology.Firstly,the preparation method of LIG is introduced,and the electrical properties of LIG prepared with different laser parameters and the optical properties in THz band are studied.Secondly,a grid THz metamaterial filter is designed,and the effects of different sizes,PI and LIG parameters on the filter performance are simulated and analyzed.Finally,the LIG technology is used to prepare the metamaterial filter.The experimental results show that the transmissivity of the filter at 0.55 THz is74.2%,and the center frequency can be increased to 0.65 THz by changing the periodic size of the filter.Because the structure of the actual filter is asymmetric,the filter has good amplitude polarization characteristics.2、A microwave broadband absorber is designed and prepared based on LIG technology,and its application is studied.Firstly,the optical characteristics of LIG at 18-28 GHz are tested,and a cross shaped microwave metamaterial absorber is designed.The effects of different structures,PI and LIG parameters on its absorption are studied through simulation.Then it is prepared by LIG technology,and the absorption effects of absorbers with different structures are measured by vector network analyzer.The three-layer absorber achieves broadband absorption of electromagnetic waves in the range of 18-28 GHz,and the absorption rate is about 80%.Finally,the shielding effect of absorbers with different structures on 24 G radar is verified.3、A structural color is designed and prepared based on LIG technology,and the sensing characteristics are studied.Firstly,a FP cavity structure color based on thin film interference is designed,and the structural color is prepared using LIG technology.By controlling laser parameters,the color of the LIG surface can be changed.Subsequently,SEM and spectrometer are used to characterize LIGs with different structural colors.Finally,due to the porous structure inside LIG,which facilitates liquid entry,its application in refractive index sensing is explored.The surface color of LIG changes with the liquid refractive index. |
