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Start Over Author "Truong, Viet Giang" Publication Type Magazines
15 results on '"Truong, Viet Giang"'

6. Fano-Resonant, Asymmetric, Metamaterial-Assisted Tweezers for Single Nanoparticle Trapping

Author

Kotsifaki, Domna G., Truong, Viet Giang, and Chormaic, Síle Nic

Abstract

Plasmonic nanostructures overcome Abbe’s diffraction limit to create strong gradient electric fields, enabling efficient optical trapping of nanoparticles. However, it remains challenging to achieve stable trapping with low incident laser intensity. Here, we demonstrate Fano resonance-assisted plasmonic optical tweezers for single nanoparticle trapping in an array of asymmetrical split nanoapertures on a 50 nm gold thin film. A large normalized trap stiffness of 8.65 fN/nm/mW for 20 nm polystyrene particles at a near-resonance trapping wavelength of 930 nm was achieved. The trap stiffness on-resonance is enhanced by a factor of 63 compared to that of off-resonance due to the ultrasmall mode volume, enabling large near-field strengths and a cavity effect contribution. These results facilitate trapping with low incident laser intensity, thereby providing new options for studying transition paths of single molecules such as proteins.

Published
2020
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7. Light-induced rotation of dielectric microparticles around an optical nanofiber

Author

Tkachenko, Georgiy, Toftul, Ivan, Esporlas, Cindy, Maimaiti, Aili, Le Kien, Fam, Truong, Viet Giang, and Nic Chormaic, Síle

Abstract

Evanescent electromagnetic fields near a waveguide can exert a transverse radiation force on scattering objects. To prove this experimentally, we demonstrate light-induced orbiting of isotropic, dielectric microparticles around an optical nanofiber that guides elliptically polarized, fundamental modes. The orbit frequency is proportional to the helicity of the coupled light. Interestingly, the observed motion is opposite to the energy flow circulation around the fiber. This result verifies the theoretically predicted negative optical torque on a sufficiently large particle in the vicinity of a nanofiber.

Published
2020

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