Paper in J Opt Soc Am A

Our paper on the optical trapping force on a particle using a radially polarised beam focused by a "devil's vortex lens" has been published as Ruili Zhang, Ziyang Chen, Jixiong Pu and P. H. Jones, 'Radiation forces on a Rayleigh particles by highly focused radially polarized beams modulated by Devil's vortex lens', Journal of the Optical Society of America A 32 797-802 (2015).

From the abstract:  The intensity and the radiation forces acting on a Rayleigh particle near the focus of completely coherent radially polarized beams whose phase are modulated by a devil’s vortex-lens (DVL) are studied. The influence of the structure of a DVL on the radiation force distribution is analyzed. It is found by numerical simulations that the modulated beams show a clear advantage over the unmodulated highly focused radially polarized beams, as the modulated beam can simultaneously trap and manipulate the multiple Rayleigh particles, while the unmodulated beam can trap only one particle under the same condition.