Abstract
Work on controlling the propagation of surface plasmon polaritons (SPPs) through the use of external stimuli has attracted much attention due to the potential use of SPPs in nanoplasmonic integrated circuits. We report that the excitation of edge plasmon by TE-polarized light passing across gapped-SPP waveguides (G-SPPWs) leads to the suppressed transmission of long-range SPPs (LRSPPs) propagating along G-SPPWs. The induced current density by highly confined edge plasmon is numerically investigated to characterize the extended radiation length of decoupled LRSPPs by the TE-induced edge plasmon. The suppressed transmission of LRSPPs is confirmed using the measured extinction ratio of the plasmonic signals which are generated from the modulated optical signals, when compared to the extended radiation length calculated for a wide range of the input power. It is also shown that LRSPP transmission is sensitive to the excited power of edge plasmon in the gap through the permittivity change near the gap. Such a control of SPPs through the use of light could be boosted by the hybridized edge plasmon mode and a huge field enhancement using nanogap, gratings or metasurfaces, and could provide opportunities for ultrafast nano-plasmonic signal generation that is compatible with pervasive optical communication systems.
Highlights
Plasmonic materials, including metals below the plasma frequency, have an inherent ability to squeeze light within deep-subwavelength volumes through the kinetic energy of free carriers inside the material [1]
In our recent study [38], we proposed that using a long-range surface plasmon polaritons (SPPs) (LRSPP) as a carrier wave, a plasmonic signal can be invertedly copied from a modulated optical signal, through use of a plasmonic signal copier (PSC)
Our findings suggest that the control of SPPs using light can be boosted by the enhancement of the induced electric current inside the plasmonic waveguide, which could be achieved by a large field enhancement in the nanogap, the plasmon passing through the gap, which is in agreement with the previous results that showed a plasmonic signal is not copied from a TM-polarized optical signal even with the power of
Summary
Plasmonic materials, including metals below the plasma frequency, have an inherent ability to squeeze light within deep-subwavelength volumes through the kinetic energy of free carriers inside the material [1]. By virtue of this free electron contribution, the diffraction limit of light can be overcome [2]. Confined edge plasmon is only excited for TE-polarized optical signals, and induces strong electric currents inside the plasmonic waveguides, leading to the suppressed transmission of LRSPPs. Considering the dependence of the input optical power and the electric permittivity change on the dielectric material near the gap on plasmonic signals in a PSC, a discussion regarding the efficient control of SPPs with light is presented
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