Plasmonic polarization generator in well-routed beaming

Abstract

As one of the recent advances of optics and photonics, plasmonics has enabled unprecedented optical designs. Having a vectorial configuration of surface plasmon field, metallic nanostructures offer efficient solutions in polarization control with a very limited sample thickness. Many compact polarization devices have been realized using such metallic nanostructures. However, in most of these devices, the functions were usually simple and limited to a few polarization states. Here, we demonstrated a plasmonic polarization generator that can reconfigure an input polarization to all types of polarization states simultaneously. The plasmonic polarization generator is based on the interference of the in-plane (longitudinal) field of the surface plasmons that gives rise to versatile near-field polarization states on a metal surface, which have seldom been considered in previous studies. With a well-designed nanohole array, the in-plane field of SPPs with proper polarization states and phases can be selectively scattered out to the desired light beams. A manifestation of eight focusing beams with well-routed polarizations was experimentally demonstrated. Our design offers a new route to achieve the full control of optical polarizations and possibly advance the development in photonic information processing. A plasmonic polarizer that can generate multiple beams with various polarizations from a single input beam has been made by a team in China. Plasmonic-based polarization devices are thinner than conventional devices for controlling polarization, but they currently offer lower functionality. Now, Tao Li and colleagues at Nanjing University have fabricated a plasmonic device capable of imparting different polarization states to multiple output beams in a controllable manner. The device is based on interference of the in-plane field of surface plasmons that generate near-field polarization states on a metal surface. The scientists show the effectiveness of their device by using it to produce eight beams with different polarizations (two linear, two circular, and four elliptical) from one input beam. The approach offers a new way for realizing full control of optical polarization.