Polarization detection employing the spectra of composite vortex beams with multi-mode: associating the polarization handedness and topological charge sign

Abstract

Polarization detection has been widely used in various fields, especially in free-space optical communication associating with orbital angular momentum (OAM). However, the bulky optical devices and the complexity of the detection process have hindered the integration and miniaturization of communication systems. Herein, a novel polarization detection method is proposed to directly identify the polarization state of incident light based on the normalized spectra of the sorted OAM modes which are converted from a composite vortex beam (CVB) to a set of spatial distinct strip type beams (STBs). The polarization states of light beam can be apparently distinguished via the combination of different STBs without redundant detection elements and the system demonstrates great robustness under specific atmospheric turbulence as well. The introduction of such a polarization detection method in future communication links will obtain lower complexity and consumption, which is very favorable regarding OAM communications.