Detecting the Topological Charge of Optical Vortex Beams Using a Focused Surface Plasmonic Beam Generator

Detecting the phase and polarization singularities of optical vortex (OV) beams is essential for integrated optical systems. So far, achieving the integration and further minimizing and stabilizing the orbital angular momentum (OAM) detector in more robust ways remain goals of related researches. In this study, we propose a semicircular nano-slit array to couple an OV beam to a focused surface plasmon beam (FSPB). The electric field intensities and movement of peak positions of FSPB are found to strongly depend on the topological charges of the incident OV beam. The positions of the FSPB can be controlled by an incident OV beam, which is left-circularly polarized (LCP) or right-circularly polarized (RCP). These results can be utilized for dynamical detection of topological charges values, positive or negative, odd or even, and polarization states of OV beams by a simple and intuitive method. Also, the electric field intensities of FSPB can be dynamically controlled by changing the structural parameters. These results provide an integrated and miniaturized method for detecting the topological charges of incident OV beams.