Research On Tunable Device Based On Graphene Metasurface

The Meta-surface has the advantages of low profile,low loss and so on.Because of its simple preparation and convenient processing,it has potential applications in the fields of new antenna,filter,communication and lens.It has become a hot research topic in the scientific field since proposed.Graphene is a new kind of nano-materials,with superior conductivity,thermal conductivity,high specific surface area,and the conductivity is adjustable,so it has potential application value in designing tunable devices.In this paper,graphene and meta-surface are combined to design and realize three different functions of graphene meta-surface devices,namely cross-polarization converter,absorber and molecular spectrum sensor.Then use CST MICROWAVE STUDIO to analysis and simulate,get the result as follows:(1)Cross-polarization converterThe cross-polarization converter is characterized by the periodic meta-surface of the graphene elliptical perforations attached to the dielectric layer and the metal plate,which achieves 96.8%conversion efficiency at 45.49THz when the graphene chemical potential is leV.Thus,for this structure,the incident polarized electromagnetic wave was almost completely rotated in its orthogonal direction after reflection.By changing the size of the chemical potential of the graphene,the adjustment of the operating frequency and the polarization conversion rate(PCR)of the converter can be realized.The PCR of the different structural parameters on the converter is discussed in detail.It is found that the conversion efficiency and operating frequency will change under different structural parameters.This indicates that the device has a flexible tunable nature(2)AbsorberThe absorber is composed of graphene meta-surface layer,medium and metal substrate.The simulation results show that the absorption rate of the absorber is 99.68%and close to 100%at 3.92THz.In addition to polarized insensitive and wide incident angle characteristics.More importantly,it is possible to dynamically control the absorption frequency by adjusting the graphene Fermi energy without changing the nanostructures,which has a huge potential value in many fields such as stealth technology.(3)Molecular spectrum sensorThe molecular spectrum sensor is composed of graphene elliptical patch and dielectric layer.The simulation experiment proves that the sensor is flexible and adjustable.The resonant frequency of the sensor can effectively tuned by changing the chemical potential of graphene without changing the structure.Changing the physical parameters of the structure and the relative permittivity of the substrate can achieve tuning of the resonant peak of the sensor.Using the sensor to detect the four molecules of ethanol,acetic anhydride,methanol and benzene,the results show that it can effectively detect and identify these four kind of molecules.Specimens of different thicknesses are tested and find that the transmission spectrum is insensitive to the thickness of the test sample,indicating that the sensor is robust.