Optical trapping of microrods: variation with size and refractive index

SH Simpson, S Hanna

Research output: Contribution to journalArticle (Academic Journal)peer-review

27 Citations (Scopus)


Optical traps can be characterized in terms of two simple parameters: the stiffness, given by the gradient of the force at mechanical equilibrium, and the strength, as expressed by the maximum restoring force available for displacement in a given direction. We present numerical calculations of these quantities for dielectric microrods of varying radius and refractive index held horizontally in pairs of holographically generated Gaussian beams. The resulting variations are seen to be influenced by optical resonances, as well as by the relative sizes of the beam waist and rod diameter. In addition, it is shown that trapping in these systems is sensitive to the polarization state of the incident field; i.e., for certain rods, trapping will occur for beams polarized perpendicular to the long axis of the rod, but not for beams polarized parallel to the long axis. Finally, friction coefficients are evaluated and used to estimate the maximum rates at which the rods may be dragged through the ambient medium. (C) 2011 Optical Society of America
Translated title of the contributionOptical trapping of microrods: variation with size and refractive index
Original languageEnglish
Pages (from-to)850 - 858
Number of pages9
JournalJournal of the Optical Society of America A
Publication statusPublished - May 2011


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