Selective remote-excitation of gap mode in metallic nanowire-nanoparticle system using chiral surface plasmon polaritons

We theoretically present the selective remote-excitation of the gap mode in the silver nanowire-nanoparticle (Ag NW-NP) system based on the excitation of the ±1-order chiral surface plasmonic polaritons (SPPs) modes, which have the crescent-shaped transverse intensity distributions and the helical propagation traces. When the gap mode at junction between the Ag-NW and the Ag-NP is excited via the +1-order chiral SPPs mode, the -1-order chiral SPP mode cannot effectively excite the gap mode, because the propagation traces of the ±1-order spiral SPPs modes have complementary intensity distributions. This selective remote-excitation method may be used in the nanowire photonics and nano-optical spectroscopy.