Alternative techniques for measuring the topological charge in optical vortices

A set of alternative methods to measure the topological charge of optical vortices is presented. The first method uses a displaced superposition of two beams with orthogonal polarization states in a Cartesian basis (horizontal and vertical), while the second method uses a superposition of auxiliary displaced vector modes with orthogonal polarizations. The information of the topological charge is embedded in the rich space variant polarization profile generated by the superposition, which can be analized through the Stokes parameters. Also, the cross-correlation function is studied and allowed us to measure the azimuthal index by performing power measurements. These methods were validated in Mach–Zehnder and Sagnac interferometers