Research On Metamaterial Devices Based On Multilayer Graphene Films

Graphene is a two-dimensional crystal material that can exist stably at room temperature and pressure.Since it was successfully peeled of in 2004 and entered the public eye,there has been a worldwide upsurge in graphene research,and have broad application prospects in photovoltaic cells,photodetectors,transistors,semiconductor devices and many other fields.As an ideal metamaterial with better performance than traditional surface plasmon materials,graphene is expected to replace the application of traditional precious metal materials in the field of metamaterials.In this dissertation,the application of multilayer graphene films in metamaterial devices was studied from microwave and terahertz frequency bands,respectively.By designing a metamaterial absorber based on a resonant cavity structure,broadband absorption in the microwave frequency band is realized;in addition,a chiral stepped "V"-shaped groove structure is studied,which realizes the selective transmission of left and right circularly polarized waves in the terahertz frequency band,and exhibits good tunability and circular dichroism.The main research contents are as follows:(1)According to the electromagnetic resonance effect of the metamaterial absorber,a metamaterial absorber based on multilayer graphene films working in the microwave frequency band is studied.By "intelligently" constructing the structure to achieve high absorption rate in the characteristic waveband and clarifying the principle of the structure achieving high absorption rate by analyzing the electromagnetic field distribution in the structure,and at the same time optimizing the structural parameters of the metamaterial absorber to make its wave absorbing performance achieve the best.Finally,the sensitivity characteristics of the absorber to oblique incidence are also analyzed.(2)A stepped "V"-shaped groove structure based on multilayer graphene films was investigated.Using the different light absorption principles of chiral structures for circularly polarized waves,the "V"-shaped groove structure of equal depth is designed into a stepped "V"-shaped groove structure with chirality.In the frequency band of 0.45 THz ? 0.65 THz,due to the circular dichroism formed by its chiral structure,the "V"-shaped groove structure truncating the left half and the "V"-shaped groove structure truncating the right half have different selectivity for left-hand circularly polarized waves(LCP)and right-hand circularly polarized waves(RCP).The research proves that the stepped "V"-shaped groove structure has transmission selectivity for circularly polarized waves in the terahertz frequency band,and by analyzing the electric field z component(Ez)of the structure and the distribution of energy flow,the internal mechanism of the chirality of the structure is elucidated.