1 Department of Photonics Engineering, Technical University of Denmark2 Teraherts Technologies and Biophotonics, Department of Photonics Engineering, Technical University of Denmark
We have previously demonstrated so-called optical twisters that can steer microparticles along spiral trajectories during optical micromanipulation. These optical twisters may be created using Fourier holograms ofthe helicoconical form, exp[ i l 8 (K- r/r0)], which is characterized by non nonseparable helical or azimuthal phase and the conical o r radial phase, and that have been shown to self-reconstruct after an obstruction . In this work, we deeanstruet the helico-conical beam (HCB) as a coherent superposition of Bessel-like beams, which carry arbitrary topological charge. Fromthis perspective, the HCB is seen as belonging to a gene ri c family of beams that can be generated using this type of superposition. Controiling this superposition enables us to generate tailared spiraling beams. We show ditterent examples of such tailared beams, such as multi-helico-conical beams (i. e., helico-conical beam with seleetable number of multiple helix) as well as multihelical beams that emulate the diffractionfree properties of its constituent Bessel-like beams.
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2. International Conference on Optical Angular Momentum (icoam2013), 2013