  A thorough analysis of the dynamics in a deterministic optical rocking
ratchet (introduced in A. V. Arzola et al., Phys. Rev. Lett. 106, 168104
(2011)) and a comparison with experimental results are presented. The studied
system consists of a microscopic particle interacting with a periodic and
asymmetric light pattern, which is driven away from equilibrium by means of an
unbiased time- periodic external force. It is shown that the asymmetry of the
effective optical potential depends on the relative size of the particle with
respect to the spatial period, and this is analyzed as an effective mechanism
for particle fractionation. The necessary conditions to obtain current
reversals in the deterministic regime are discussed in detail.
