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Journal of Nanophotonics

Clustering of optically trapped large diameter plasmonic gold nanoparticles by laser beam of hybrid-TEM11* mode
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Paper Abstract

Multiple trapping and clustering of gold nanoparticles (Au-NPs) of 254- and 150-nm diameter was affected using optical tweezers near the plasmon excitation wavelength. To ensure that the gradient force exceeded the sum of multiply-enhanced destabilizing absorption and scattering forces originating from plasmon excitation, embedded intensity gradient regions of a spatially featured asymmetric (SFA) laser beam were exploited. Thus, an intra-cavity generated SFA beam, also referred as hybrid TEM11* mode, is an intermediate between pure TEM00 and TEM11 beams and was directly obtained from a diode-pumped solid state (Nd:YAG) laser resonator without introducing any external beam modulation devices. The parabolic Gaussian-ray model of a tightly focused laser beam was adopted to evaluate the radiation forces including the volume-correction factor raised from fractional polarization of such large diameter Au-NPs under laser illumination. Temperature rise of Au-NPs and its dissipation profile in surrounding medium has also been presented. This multiple trapping and clustering of Au-NPs at plasmon excitation wavelength using sufficiently low power could be realized due to embedded intensity gradients of the SFA beam. The study might be useful for understanding the light-matter interaction, improving the sensitivity of diagnostics, and safety and efficacy of therapeutic nanotechnologies in medicine, photothermolysis, and surface-enhanced Raman spectroscopy, etc.

Paper Details

Date Published: 1 January 2011
PDF: 18 pages
J. Nanophoton. 5(1) 053511 doi: 10.1117/1.3600647
Published in: Journal of Nanophotonics Volume 5, Issue 1
Show Author Affiliations
Ranjeet Kumar, Indian Institute of Technology Delhi (India)
Dalip S. Mehta, Indian Institute of Technology Delhi (India)
Chandra Shakher, Indian Institute of Technology Delhi (India)

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