Enantiomeric excess controlled fractional orbital angular momentum of optical vortex beams

The tuning of the fractional orbital angular momentum of an optical vortex beam is proposed and experimentally demonstrated using a common-path stable technique by controlling the enantiomeric excess of an optically active material in an enantiomeric mixture. The projection of the generated vector vortex beam onto horizontal polarization results in an optical vortex beam with its vortex position at the center. The radial position of the optical vortex is controlled by passing the vector vortex beam through an enantiomeric mixture and controlling the enantiomeric excess of an optically active material. The orbital angular momentum of the resulting off-axis beams is measured as a function of different enantiomeric excesses using a cylindrical lens and intensity moments. The results are compared with those of diagonal polarization projection. The non-canonical nature of the generated off-axis vortex is also characterized using Fourier fringe analysis. These results can be useful in optical micro manipulation and also in the detection of enantiomeric impurities.