Optical forces on cylinders near subwavelength slits illuminated by a photonic nanojet

We discuss optical forces exerted on particles, either dielectric or metallic, near a subwavelength slit illuminated by a photonic nanojet. We compare those cases in which the Mie resonances are or are not excited. The configurations on study are 2D, hence those particles are infinite cylinders and,...

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Bibliographic Details
Published inOptics communications Vol. 294; pp. 351 - 360
Main Authors Valdivia-Valero, F.J., Nieto-Vesperinas, M.
Format Journal Article
LanguageEnglish
Published Elsevier B.V 01.05.2013
Subjects
Apertures
Diffraction
Optical tweezers or optical manipulation
Resonators
Surface plasmons
Apertures
Diffraction
Optical tweezers or optical manipulation
Resonators
Surface plasmons
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Summary:We discuss optical forces exerted on particles, either dielectric or metallic, near a subwavelength slit illuminated by a photonic nanojet. We compare those cases in which the Mie resonances are or are not excited. The configurations on study are 2D, hence those particles are infinite cylinders and, in order to obtain extraordinary transmission, the illuminating beam is p-polarized. We show the different effects of these particle resonances on the optical forces: while whispering gallery modes under those illumination conditions weaken the force strength, this latter is enhanced by localized plasmon excitation. Also, illuminating the slit with a nanojet enhances the optical forces on the particle at the exit of the aperture by a factor between 3 and 10 compared with illumination of the slit with a Gaussian beam. In addition, the pulling force that such a small resonant metallic particle suffers on direct illumination by a nanojet can change by the presence of the slit, so that it may become repulsive at certain lateral positions of the particle.
ISSN:0030-4018
1873-0310
DOI:10.1016/j.optcom.2012.12.025