DETERMINATION OF THE TOPOLOGICAL CHARGE OF A PHASE SINGULAR BEAM USING A NEMATIC LIQUID CRYSTAL FRESNEL LENS
Belarusian State University, Belarus
Currently, many scientific groups are engaged in the study of phase singular beams carrying orbital angular momentum due to the active use of topological charge for the implementation of qudits (multilevel quantum states) in cryptography, quantum information and communication. A simple interference method for analyzing the phase topology of optical vortices based on the preliminary diffraction of singular light beam on an achromatic electrically controlled nematic liquid crystal cell, which is a Fresnel zone plate, is proposed and implemented here. The efficiency of the method has been tested experimentally and theoretically in the visible and near-infrared range. The use of an electrically controlled achromatic Fresnel lens based on a nematic liquid crystal in singular optics offers a promising method for determining the topological charge of a phase singular light beam due to the possibility of analyzing signals coming from free space in real time without changing the circuit based on the possibility of switching on/off the proposed element. The developed method will help expand the scope of application of phase singular beams and significantly simplify existing technologies.