Study On Polariton Resonance And Modulation Mechanism In Polar Crystal

The imaging resolution of conventional optical elements lenses or parabolic mirrors cannot break the diffraction limit.Research in nanophotonics,represented by plasmon polaritons,aims to understand and manipulate light and matter interactions at sub-wavelength scales.The ability of plasmon polaritons to exceed the conventional diffraction limit and the promise of their applications have attracted much attention.Recent studies have confirmed that surface phonon polarization(SPhP)supported in polar crystal materials have lower loss and localized capabilities than surface plasmon polaritons(SPP)in noble metals,and are an efficient solution for realising nano-photonic components.In this paper,we focus on polar crystalline material supported SPhP,which have excellent potential for applications in infrared thermal radiation,light detection and sensing,and understand the spectral response of SPhP by comparing far-field and near-field spectra:A microstructure based on 6H-silicon carbide(6H-SiC)has been designed that exhibits good spectral tunability and strong field limiting capability.The study of the amplitude and frequency of resonant optical surface waves can provide some theoretical reference for the improvement of the performance of mid-infrared micro-nano devices.Folded optical phonons in a periodic array of Localized Surface Phonon Polaritons(LSPhP)can effectively control the phonon scattering process.The transverse dipole(TD)mode in the 6H-SiC hollow cylindrical antenna array exhibits excellent stabilisation efficiency and broad spectral tunability.The dependence of the local field on the size and periodicity of the structure in the polarisation mode is investigated to elucidate the exotic optical properties of the microstructure.The near-field coupling mechanism of the polarisation mode is explored in depth by combining a multilevel decomposition of the current distribution values.An ultra-thin heterogeneous nanostructure consisting of α-molybdenum trioxide(αMoO3)nanoribbons,graphene nanoribbons and a dielectric spacer layer was investigated.The coupling between hyperbolic phonon polaritons(HPhP)and SPP of graphene leads to Reciprocal Polariton-induced Transparency(RPoIT).The nature of the near-field coupling is further analysed in relation to the dipole distribution values of the multipole decomposition.The heterojunction structure can be tuned by varying the geometrical parameters of the heterostructure and the chemical potential of graphene,and the numerical results show that the heterojunction structure has promising applications in refractive index sensors and midinfrared(MIR)absorbers.Overall,based on the study of SPhP,this paper presents two polar crystal micro-nano structures,reveals the novel optical phenomena and the physical mechanisms behind them,and demonstrates their value for the development of nanodevices and multifunctional hybrid polarisation devices.The authors believe that these works will provide new ideas for the application of SPhP.