Research On Electric/Magnetic Localized Resonance Excitation And Its Application In Metamaterials

The combination of metamaterials and surface plasmons technology to realize the manipulation of light and the enhancement of local electromagnetic fields is a key scientific and technological problem in the design of micro-nano devices,and has become one of the research hotspot in recent years.This thesis first study the broadband absorption enhancement effect of single-layer graphene based on magnetic dipole resonance in metamaterials,and designed an ultrafast electro-optical switch based on the tunable Fermi level of graphene in the near infrared region.Secondly,we aim to explore the strong coupling effect between two high-Q plasmonic modes in a spherical hyperbolic metamaterial(HMM)cavity,which can produce an ultralarge and ultrabroadband Rabi splitting.This thesis first introduces the related principles,characteristics,excitation methods and related applications of surface plasmons.Secondly,it introduces the principles and characteristics of metamaterials,and then further introduces the principles and applications of metamaterials,such as magnetic surface plasmons.Finally,this thesis innovatively investigates the excitations and interactions of local electric and magnetic resonances in two complex metamaterials,exploring the related applications in new micro-nano devices.The main content of the thesis includes the following two aspects:1.We innovatively use the magnetic dipole resonance supported by metal nanoparticle/dielectric/metal film(MIM)metamaterials to enhance the absorption for single-layer graphene.First,we demonstrate numerically a broadband absorption enhancement of monolayer graphene,due to the magnetic dipole resonance in MIM metamaterials.Secondly,The broadband light absorption in monolayer graphene can be largely modulated to realize an electrically switchable effect based on the tunable interband transition of graphene.Especially,the absorption modulation depth is able to vary quickly from almost zero to nearly 100% in a very narrow wavelength range when the interband transition is tuned to the vicinity of magnetic dipole resonance.Our work should have potentials in the fields of graphene-based optoelectronic electrically modulated switch.2.We further innovatively investigate the strong coupling effect between two high-Q plasmonic modes in a spherical HMM cavity formed by 7 alternating layers of silver/dielectric layers wrapping a dielectric nanosphere core.Firstly,we theoretically demonstrate a very large Rabi splitting energy of up to 788 me V arising from the strong coupling between high-Q plasmonic whispering-gallery mode and high-Q cavity plasmon resonance in the spherical HMM cavity.In addition,the new hybrid modes formed by the strong coupling are demonstrated to exhibit longer lifetime of up to71.9 ～ 81.6 fs,and achieve the electric field intensity enhancement at both the dielectric core and dielectric layers.More importantly,by simply adjusting the dielectric core sizes,the strong coupling is demonstrated to happen at the same dielectric core index and to be turned across a broad spectral range.These results may find potential applications in bright single photon source and the photovoltaic devices.