| Light-matter interaction is promoted by mode resonance and coupling in metamaterials,which improved the further applications of integrated optoelectronic device.Polaritons polaritons can beat the diffraction limit of classical optics by confining light into regions that are much smaller than its wavelength,and lead to advances in nanophotonics by enabling manipulation of photons at nanoscale.Recently,the phonon polaritons derived from coupling between lattice vibrations and the infrared light have become a hot spot in the field of metamaterials research.Hexagonal boron nitride(hBN)phonon polaritons have attracted great attentions because of their advantages such as low loss,long lifetime and hyperbolic dispersion.Designing appropriate structures will realize high confinement and high-Q factor resonance,which is conducive to the development of the applications of mid-infrared nanophotonics phonon devices in biosensing,sub-wavelength focusing and imaging,enhanced light emission and other applications.In this dissertation,in order to solve the problem of low Q resonance and weak local field in hBN phonon polaritons resonator,we introduced optical tamm state resonance and mode coupling,and studied the resonance of Tamm phonon polaritons mode in hBN hybrid structure,and the strong coupling characteristics of plasmon and phonon polaritons.By means of the optical Tamm state structure,we obtained the polaritons mode resonance with ultra-high filed confinement,and realized the phonon-type devices with high Q factor.Multilayer hybrid structures based on optical Tamm state,and graphene/hBN hybrid structure possess controllable strong mode coupling with a dual-narrow-band perfect absorption,which offers new possibilities for developing various on-chip optical detection,sensing,filtering,and thermal emitter devices.The characteristics of hBN phonon polaritons in mid-infrared are studied.Utilizing the analytical method of guided mode,the dispersion of hBN hyperbolic phonon polaritons are investigated,and the thickness-dependence of the hyperbolic phonon polaritons and the propagation characteristics of higher-order mode are discussed.The resonance mechanism of volume hyperbolic phonon polaritons and surface hyperbolic phonon polaritons are analyzed by using hBN nanoribbon structure.In order to study the difference between phonon polaritons and electromagnetic resonance in hBN at the same nanoscale,due to the large gap and low extinction coefficient,we designed the hBN nanodisks and asymmetric double hBN nanorods metastructures,and studied the confinement of non-radiative mode with anapole and bound state in the continuum.High Q resonances in visible with anapole and quasi bound state in the continuum are realized,which offers possibilities for developing the broadband UV source.The characteristics of Tamm phonon mode in hBN hybrid structure are studied,which breaks through the bottleneck of low Q resonance in hBN simple resonators.The excitation of Tamm phonon mode is verified by analytical method,and the effects of photonic crystal period,Ge layer,hBN thickness and incident condition on the critical coupling condition of the Tamm phonon are discussed.Then,we designed Tamm absorber derived from Tamm plasmon polaritons and refractive index sensor based on Tamm phonon polaritons.In hybrid Tamm structure with metal nanodisk array,the coupling of lattice resonance and Tamm plasmon mode promoted the near perfect absorption.Optical Tamm state can be controlled effectively through changing the geometric parameters of the nanostructure,which increased the degree of freedom to manipulate the Tamm mode.Based on the high Q resonance of the Tamm phonon mode in hBN hybrid structure,the effects of the analyte thickness,the photonic crystal period and the thickness of hBN on the sensitivity and FOM of the proposed sensor with small refractive index changes are discussed.The sensitivity of the gas detection is 4.0 μm/RIU,and the FOM can reach to 2312 /RIU.Strong longitudinal coupling of plasmon and phonon polaritons in Tamm structure realize the hybridization of Tamm plasmons and phonon polaritons.The influence of incident direction on the Tamm plasmon is analyzed,and the mechanism of dual resonance mode in Reststrahlen band of hBN is discussed according to the optimized structure parameters with respect to Tamm plasmon.An obvious anticrossing phenomenon is observed through manipulating the thickness of the Ge layer,indicating the strong coupling of Tamm plasmon mode and the Tamm phonon mode under the condition of zero detuning.Then,the mixing fraction of the contribution of the Tamm plasmon and the Tamm phonon mode to the hybrid mode is quantitatively analyzed with coupled oscillator theory.The variation trends of these two Tamm modes with Ge layer,photonic crystal period and incident angles are exhibited clearly.The mechanism of DBR period on strong coupling is revealed,and the Rabi splitting energy can reach to 10.1 me V.Based on the hBN/graphene hybrid structure,the coupling between the hyperbolic phonon polaritons and surface plasmon polaritons is studied,and the electrical tuning for resonance absorption resulted from phonon polaritons is realized with hBN/graphene heterostructure nanodisk array.According to the dispersion characteristics of the hybrid polaritons modes,we analyzed the reasons for the high sensitivity of electric tuning in the graphene/hBN/graphene hybrid structure.The absorption with wide tunability in the Reststrahlen band reach more than 90% under the electronic modulation of graphene Fermi level.which overcomes the difficulty of untunable phonon polaritons caused by the wide band gap of hBN.From the dispersion characteristics of the hybrid modes,the surface plasmon polaritons out of the Reststrahlen band are strongly modified by the hyperbolic phonon polaritons,and the resonance absorptions with narrow-band out of the Reststrahlen band are exhibited,which is potential to narrow-band thermal radiation device.In addition,the dependence of incident polarization and angle on the two-hybrid mode is studied,which indicates that the resonance absorber can operate in a wide-angle range,and is almost independent to the incident angle and polarization.The proposed hybrid structure expands the application of phonon-type devices for mid-infrared nanophotonics and could enable the creation of novel actively tunable,low-loss application at the nanoscale. |
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