Chiral-dependent Terahertz Transmission And Polarization Control Based On Surface Plasmons

In recent years,terahertz(THz)technology have attracted huge attentions owning to its unique properties,which exhibits great potential in high-speed communications,radar,security check,drug testing and so on.The development of the THz technologies requires efficient THz sources,detectors and various function devices.So far,significant progresses have been made in the THz sources and detectors,however,the corresponding THz function device is still lacking.The emergence of metasurfaces provides a new way for developing the THz function devices.In this paper,we proposed a meta-hole structure based on surface plasmons excited by metasurfaces,and we realized:1.Chiral-dependent terahertz transmission: In this thesis,we proposed a new chiral-dependent transmission-type metasurface.Comparing to conventional chiral metasurface,we introduce chiral-dependent propagating surface plasmons and spin-selective interference using a meta-hole structure.Giant chiral-dependent terahertz transmission is achieved.Theoretical analysis shows that spin-orbital angular momentum conversion plays an essential role in the interaction process.2.Terahertz polarization control: By designing the process of the spin-orbital angular momentum conversion in the proposed meta-hole structure in another way,THz polarization control is achieved,where the two interference components are in different circular polarization state.As any polarization can be seen as a combination of the two circular polarizations,therefore,by designing the amplitudes and phase differences between these two interference components,nearly arbitrary polarization state can be obtained.