Optical twisters: beams having twists in both phase and amplitude [invited]

Vincent R. Daria (Invited author), Darwin Palima (Invited author), Jesper Glückstad (Invited author)

Research output: Contribution to journalConference articleResearchpeer-review

Abstract

We describe a diffracting beam with orbital angular momentum (OAM) but with a helical profile in both phase and amplitude components of the beam. This is different from Laguerre-Gaussian (LG) beams where only the phase component has a helical profile. Such profile in LG beams introduces a phase singularity at the centre and produces a dark region surrounded by a ring-shaped light pattern. For LG-beams, the ring radius is proportional to the degree of helicity or topological charge of the beam. The beam we describe here is initially characterized with an apodized helical phase front at the outskirts and linearly scaled towards no phase singularity at the centre of the beam. At the focal volume, we show that our beam forms an intensity distribution that can be accurately described as an "optical twister" as it propagates in the forward direction. Unlike LG beams, an optical twister can have minimal changes in radius but with a scalable OAM. Furthermore, we characterize the OAM in terms of its capacity to introduce spiral motion on particles trapped along its orbit. We also show that our "optical twister" maintains a high concentration of photons at the focus even as the topological charge is increased. Such beams can be applied to fundamental studies of light and atoms such as in quantum entanglement of the OAM, toroidal traps for cold atoms and for optical manipulation of microscopic particles.
Original languageEnglish
Journalproceedings of SPIE, The International Society of Optical Engineering
Volume7613
Pages (from-to)761304
ISSN0277-786X
DOIs
Publication statusPublished - 2010
EventComplex Light and Optical Forces IV : New complex light beams - San Francisco, CA, USA
Duration: 1 Jan 2010 → …

Conference

ConferenceComplex Light and Optical Forces IV : New complex light beams
CitySan Francisco, CA, USA
Period01/01/2010 → …

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