Abstract
A tunable plasmonic nanocavity which consists of a metallic groove with submerged ultra-thin Ge2Sb2Te5 film is proposed for controlling the on/off characteristics of directional surface plasmon polaritions (SPPs) launching. Different mechanisms of launching SPPs using two orthogonal incident polarizations are investigated to reveal the SPP generation characteristics from the proposed nanocavity. By choosing the appropriate position of Ge2Sb2Te5 film, we report that the directional launching characteristics of SPPs can be controlled by changing the phase state of extremely small volume of Ge2Sb2Te5 film, which shows up to 37 dB of extinction ratio changing characteristics.
Highlights
S urface plasmon polaritons (SPPs) has been greatly contributed to the various fields of nanophotonics,1) since SPPs can be highly confined below the diffraction limit and strongly related to the aspect of electron dynamics on metal surfaces.2) Such properties of SPPs make possible to develop numerous integrated plasmonic devices such as plasmonic lens,3) negative refractive index waveguides,4,5) directional launchers,6,7) fiber sensors,8) and metasurfaces.9–11) Especially, fascinating research fields that focused on observing extraordinary nature of SPPs caused by strong light-matter interaction are demonstrated, such as spin–orbit interaction in plasmonic vortex lenses,12) photonic spin-Hall effects,13) and nonlinear effects14) because these phenomena are usually very weak in typical dielectric-based photonic structures
Various candidate materials are still competitive for active tuning of SPPs; such as graphenes,15,16) liquid crystals on silicon,17) VO2,18) and chalcogenide phase change materials such as Ge2Sb2Te5 (GST), etc.19–21) Among of them, active plasmonic devices using the phase change characteristics of GST are tentatively reported within recent years since GST has unique characteristics such as a very large permittivity change in wideband spectrum from visible to mid-infrared, non-volatile, reconfigurable, and high compatibility with conventional semiconductors.22) the recent publications shows that GST can be highly applicable to various nanophotonic applications such as all-optically driven memory, active metasurfaces, tunable perfect absorber, and holographic display panels.19–25)
It has been shown that the electron dynamics near the nanoslit caused by incident electric fields or magnetic induction currents can strongly affect to the launching direction and phase of SPPs.26) Spatially changing phase profile of an incident magnetic field perpendicular to nanoslit polarization with an obliquely incident wave can provide symmetric parity of excited SPPs, whereas anti-symmetric parity of excited SPPs is formed by perpendicular-to-slit electric field polarization
Summary
S urface plasmon polaritons (SPPs) has been greatly contributed to the various fields of nanophotonics,1) since SPPs can be highly confined below the diffraction limit and strongly related to the aspect of electron dynamics on metal surfaces.2) Such properties of SPPs make possible to develop numerous integrated plasmonic devices such as plasmonic lens,3) negative refractive index waveguides,4,5) directional launchers,6,7) fiber sensors,8) and metasurfaces.9–11) Especially, fascinating research fields that focused on observing extraordinary nature of SPPs caused by strong light-matter interaction are demonstrated, such as spin–orbit interaction in plasmonic vortex lenses,12) photonic spin-Hall effects,13) and nonlinear effects14) because these phenomena are usually very weak in typical dielectric-based photonic structures. Hee-Dong Jeong1, Chi-Young Hwang2, Hyuntai Kim3, Muhan Choi1, and Seung-Yeol Lee1*
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