Polarization vortices generation by diffraction from a four quadrant polarization mask

In this work we analyze the generation of an array of polarization singularities (polarization vortices) in the diffracted field produced by a simple four quadrant polarization mask, which transmits two orthogonal linear states in different quadrants. We use the Jones matrix method to analyze the polarization and diffraction characteristics of the diffracted field. We show that the same four quadrant mask can be used to generate either azimuth or ellipticity singularities simply by changing the input polarization. We experimentally verify the theory by generating the four quadrant polarization mask using a twisted nematic liquid crystal display. We show experimental results that confirm the theoretical predictions.