Nanometer near-field localization and enhancement in a split two-dimensional plasmonic system at terahertz frequencies

We study terahertz excitation of plasmons in a two-dimensional electron system with a periodic metal grating coupler. We assume that a negative electric potential is applied to one of the grating fingers, which results in forming a slit in an otherwise continuous two-dimensional plasmonic system. We analyze numerically the excitation of plasmons in such system and study plasmonic field near the slit. We predict a deep subwavelength localization of plasmons and a dramatic field enhancement at the slit edges.