Poster/7. Plasmonics and Metamaterials

Nanjing University of Science and Technology;Nanjing University

A chiral plasmonic lens (CPL) suitable for circular polarization analyzer is designed and numerically investigated. It consists of two arrays of rectangular nanoslits milled into a gold film along Archimedes spirals. The CPL can couple circularly polarized illumination into two SPPs waves, which can interfere constructively or destructively according to both the structure of the CPL and the handedness of circular polarization possessed by incident beam. We demonstrate both theoretically and numerically that the designed structure can convert an incident circularly polarized light beam with prescribed chirality into a Bessel-like distributed focus, but the circularly polarized one with the opposite chirality cannot be transmitted and focused by the same CPL due to the alternative chirality. Further, three-dimensional finite-difference time-domain (FDTD) simulations show that an ultrahigh extinction ratio up to ten thousands of the CPL is numerically achieved with a device size less than 10 λspp, which is two orders higher than that of a conventional plasmonic circularization analyzer with single Archimedes-spiral groove. The designed structure can be widely used in miniature polarimeter and detection of spin angular momentum.