Exceptional point-based plasmonic metasurfaces for vortex beam generation
Ho Ming Leung, Wensheng Gao, Ranran Zhang, Qiuling Zhao, Xia Wang, C. T. Chan, Jensen Li, Wing Yim Tam
Abstract
An exceptional point occurring in a tailor-made lossy optical system has been recently found to alter optical properties in counter-intuitive ways. In the context of tunable plasmonic devices, exceptional points can be useful as a driving mechanism to enhance tunability. Here, we experimentally demonstrate how a plasmonic exceptional point can be incorporated in metasurface Q-plates to have the generated vortex beam tuned through a change of structural parameter. We have observed an orbital rotation in the far-field by 45 degrees in crossing the exceptional point. We expect a new generation of tunable plasmonic devices in polarization control, beam structuring and holograms, which can take advantage of the huge sensitivity from exceptional points.