Optical multi-trapping by Kinoform m-Bonacci lenses

Optical manipulation is interfacing disciplines in the micro and nanoscale, frommolecular biology to quantum computation. Versatile solutions for increasingly more sophisticatedtechnological applications require multiple traps with which to maneuver dynamically severalparticles in three dimensions. The axial direction is usually overlooked due to difficultiesin observing particles away from an objective-lens focal plane, a normal element in opticaltweezers, and in managing interparticle distances along the trapping beam propagating direction,where strong radiation pressure and shadowing effects compromise the simultaneous and stableconfinement of the particles. Here, aperiodic kinoform diffractive lens based on the m-Bonaccisequence are proposed as a new trapping strategy. This lens provides split first-order diffractive fociwhose separation depends on the generalized m-golden ratio. We show the extended manipulationcapabilities of a laser tweezers system generated by these lens, in which concomitant trapping ofparticles in different focal planes takes place. Positioning particles in the axial direction withcomputer-controlled distances allows dynamic three-dimensional all-optical lattices, useful in avariety of microscale and nanoscale applications.