Liquid crystal retarder modulation for generating real time non-uniformly polarized beams

Beams of non-uniform elliptical polarization distribution have been obtained in real time from a radially or an azimuthally polarized beam by using a liquid crystal variable retarder (LCVR), which can be modulated by varying the applied voltage. The local polarization states analyzed by the Stokes parameters strongly depend on the spatial position and the phase retardation angle of the LCVR. The angular momentum of the beams varies in each quadrant, where the polarization rotated direction for the radially polarized beam through the LCVR is right-handed in the first quadrant and the third quadrant, while it is left-handed in the second quadrant and the fourth quadrant. However, the polarization rotated direction for the azimuthally polarized beam through the LCVR is the inverse of that for the radially polarized beam.