Study of surface plasmon chirality induced by Archimedes’ spiral grooves

A chirality of surface plasmons excited on a silver film with Archimedes' spiral grooves during incidence of a circularly polarized light is analytically and numerically studied by using the finite-difference time-domain (FDTD) modeling method. We found that the surface of a plasmon has selective chirality, which is given by the sum of the chiralities of the incident light and the spiral structure. The surface plasmons with the chirality lead to zero-order, first-order, and high-order evanescent Bessel beams with electric charge distributions on the film. This selectivity could be widely applied for chiral detection of the incident light and chiral excitation of several optical modes in nanophotonics.