Non-diffracting beam synthesis used for optical trapping and delivery of sub-micron objects

We demonstrate the use of interference between non-diffracting Bessel beams (BB) to generate a system of optical traps. They offer sub-micron particle confinement, delivery and organization over a distance of hundreds of μm. We analyze system of two identical counter-propagating BBs and the case of two co-propagating BBs with different propagation constants separately. In both of these cases, the interference results in periodic on-axis intensity oscillations involving particle confinement. Altering the phase of one of the interfering beams, the whole structure of optical traps can be shifted axially. Implementing this conveyor belt enables the particle delivery over the whole distance where the optical traps are strong enough for particle confinement. Experimentally we succeeded with generation of both of these systems. In case of two counter-propagating BBs we observed a strong sub-micron particle confinement, while in case of co-propagating BBs the confinement was observed only with help of fluid flow against the radiation pressure of both beams.