Optical trapping with π-phase cylindrical vector beams

The use of π-phase radially and azimuthally polarized vector beams in optical trapping is investigated. We find that by tuning the relative phase between the eigenmodes comprising the beams, the optical forces applied to a trapped particle are modified. In particular, axial trapping efficiency is enhanced with increasing z polarization and the lateral trapping efficiency of the vector beams is reduced compared to a Gaussian input beam. In addition, this is the first experimental demonstration of low-power optical trapping in an aqueous environment using vector beams, which may have important applications in biological systems.