Characterizing conical refraction optical tweezers

C. McDonald*, C. McDougall, E. Rafailov, D. McGloin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Conical refraction occurs when a beam of light travels through an appropriately cut biaxial crystal. By focusing the conically refracted beam through a high numerical aperture microscope objective, conical refraction optical tweezers can be created, allowing for particle manipulation in both Raman spots, and in the Lloyd/Poggendorff rings. We present a thorough quantification of the trapping properties of such a beam, focusing on the trap stiffness, and how this varies with trap power and trapped particle location. We show that the lower Raman spot can be thought of as a single-beam optical gradient force trap, while radiation pressure dominates in the upper Raman spot, leading to optical levitation rather than trapping. Particles in the Lloyd/Poggendorff rings experience a lower trap stiffness than particles in the lower Raman spot, but benefit from rotational control.

Original languageEnglish
Pages (from-to)6691-6694
Number of pages4
JournalOptics Letters
Issue number23
Publication statusPublished - 1 Dec 2014

Bibliographical note

Funding: EPSRC (EP/H004238/1), and for the award of a studentship


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