Study On Plasmonic Tamm States And Its Applications

Surface plasmon polaritons(SPPs),profited by the unique electromagnetic field confinement and localized field enhancement,have developed into an important subfield of nano-optics.Until now,SPPs have been intensively applied in enhancing nonlinearities,surface-enhanced Raman scattering,surface-enhanced fluorescence,nanosensor,all-optical circuits,optical communication and signal processing.Plasmonic Tamm states(PTSs),as a new type of nanoscaled Tamm states,have combined the advantages of SPPs and optical Tamm states.In this dissertation,we investigated the PTSs in insulator-metal-insulator(IMI)and metal-insulator-metal(MIM)waveguides and the related applications in electromagnetic nanofocusing and photonic integration with the help of the impedance-based transfer matrix method.The key works and results are shown as follows:(1)Based on the transmission line theory,we have deduced the impedance-based transfer matrix(TMM),which is applicable to analyze the periodic structure in plasmonic waveguide.And the approximate expression of 3D impedance is proposed.Meanwhile,the main idea of finite difference time domain method(FDTD)is analyzed according to the curl equation of Maxwell's equations.(2)The PTSs configuration based on the MIM waveguide is proposed by periodically modulating the width of the insulator,in which the nanofocusing of the free-space optical energy is realized assisted by the air-gap coupler.The effective couplings between free space light and SPPs modes are realized with high coupling efficiencies for both 2D and 3D configurations at the resonant wavelength,moreover,the electromagnetic field intensities are enhanced by three orders of magnitude.Besides the field confinement in the perpendicular direction,the field is confined along the propagative direction.Compared to the traditional V-shaped plasmonic waveguide,the experimental fabrication is achievable with standard nanofabrication techniques such as electron-beam lithography and focused ion beam milling,which greatly reduce the processing difficulties.(3)A new type of PTSs based on IMI bragg reflector is designed by periodic modulation of the dielectrics surrounding the metal core.Two independent IMI PTSs can be excited in the same configuration that are related to the even and odd modes in the IMI waveguide.In addition to the realization of prominent electromagnetic enhancement,the system can work as an optical switch via the transition between the two modes at resonant wavelength.The extinction ratio can reach 18.83 for period number N =8 at wavelength 1550 nm.These features offer IMI PTSs great potentials for the integrated photonic devices and all-optical circuits.