Excitation And Modulation Of Metal/dielectric Metasurface Phonon Polaritons

In micro-nano photonics,electromagnetic“hot spot”(strong localization of electromagnetic field)has always been the focus of optical devices.Therefore,it has attracted the attention of many researchers in the optical field at home and abroad.Compared with surface plasmon polaritons,phonon polaritons have lower intrinsic optical loss and longer phonon lifetime,thus making up for the inherent defects of surface plasmon polaritons,which is conducive to the further realization of electromagnetic“hot spot”.Therefore,it is necessary to explore the stimulation and manipulation of phonon polaritons.With the progress and development of micro-nanostructure technology,the emergence of metasurface provides a new research platform for exploring the stimulation and manipulation of phonon polaritons in the infrared band.Based on this,two methods to stimulate and manipulate phonon excitons are proposed in this paper.First,the phonon polaritons are manipulated by designing the metasurface of the plasma system.Second,the surface phonon polaritons are stimulated and manipulated by the design of metal/dielectric metasurface structures.These provide a new idea for the further development of infrared optical devices.This topic mainly includes the following three works.1.Study on the space and anisotropy of phonon thermal radiation in metal/dielectric thin films.Firstly,the structures of Si/Al(metal)/Si O₂thin film(dielectric)and Si/Si O₂thin film(dielectric)were prepared by plasma enhanced chemical vapor deposition and other micro-nanostructure preparation methods.Then the reflection spectrum,transmission spectrum and absorption spectrum of the two samples were simulated by FDTD Solutions software.It was found that the metal/dielectric was more conducive to the stimulation and manipulation of phonon modes.In order to further explore the intrinsic properties of phonon modes,the diagram of thermal radiation angle of Si/Al/Si O₂thin films was measured by Fourier transform infrared spectrometer,and the space and anisotropy of phonon thermal radiation of phonon modes were explored.These are helpful for the development and utilization of infrared optical devices.2.The stimulation and manipulation of longitudinal optical phonons in metal/dielectric films.On the basis of the first work,we designed the Si/Al/(metal)Si O₂film(dielectric)/Al grating.In the experiment,the sample was prepared by electron beam evaporation and other micro-nanostructure preparation methods,and the thermal radiation spectrum of the sample was tested by Fourier infrared spectrometer.The absorption spectrum simulation of FDTD Solutions software and the double-coupling harmonic oscillator model of MATLAB were obtained.It is confirmed that the magnetic dipole resonance modes are strongly coupled with the longitudinal optical phonon modes,which makes the longitudinal optical phonon modes radiate strongly at the normal incidence.In addition,it is found that the surface lattice resonance modes are coupled with the longitudinal optical phonon modes,not only the longitudinal optical phonon modes are not excited,but the surface lattice resonance modes are annihilated.This opens up a new path for the development of low-loss materials and field strength localization.3.The stimulation and manipulation of surface phonon polaritons in composite polar dielectric metasurface.On the basis of the previous two works,we designed a composite Si/Al(metal)/Si C thin film(dielectric)/Si O₂grating(metal)by FDTD Solutions software.Due to the existence of metal/dielectric structure,the surface lattice resonance modes gradually red-shifted with the change of structural parameters,and coupled with the surface phonon polaritons,magnetic dipole resonance modes and transverse optical phonon modes.This coupling greatly broadens the regulatory band of surface phonon polaritons,leading to expand the application range of surface phonon polaritons.This provides a new idea for infrared optical devices based on surface phonon polaritons.