Grand Séminaire d'Institut

Vendredi 16 Mars 2018 à 11h00.

Particle Trapping in Near-Field Optics of Ultrathin fibres and Plasmonic Tweezers

''In this work, I will present the angular momentums of light guided in optical ultrathin fibres and review how to transfer this momentum to microparticles trapped near the fibre surface. I will discuss the possibility of generating the higher-order modes of complex structured light in a microfibre system. We find that the angular momentum of these modes can provide an additional degree of freedom in particle trapping, rotation and transportation at the fiber surface.1-3 This work is a first step towards trapping and controlling micro- and nanoparticles and laser-cooled atoms for future quantum fibre networks.4
In order to trap nanoparticles in the Rayleigh regime i.e., where the particle size is much smaller than the trapping wavelength. We use a plasmonic nanotweezer based on an asymmetric annular aperture structure.5 Using this device, particles with sizes ranging from 20 nm to 1 μm were trapped on the plasmonic array surface while keeping at very low powers of the incident beam (below 1 mW). The observation demonstrated that this device could be integrated into a lab-on-a-chip system for trapping and manipulation of micro and nano-objects in aqueous environments.
References
1. Fam Le Kien, T. Busch, V.G. Truong, and S. Nic Chormaic, Higher-order modes of vacuum-clad ultrathin optical fibres, Phys. Rev. A 96, 023835 (2017).
2. A. Maimaiti, V.G. Truong, et al, and S. Nic Chormaic, Higher order microfibre modes for dielectric particle trapping and propulsion, Sci. Rep. 5, 909077, (2015).
3. A. Maimaiti, V.G. Truong, et al, and S. Nic Chormaic, Nonlinear force dependence on optically bound micro-particle arrays in the evanescent fields of fundamental and higher order microfibre modes, Sci. Rep. 6, 30131, (2016).
4. M. Daly, V. G. Truong, C. F. Phelan, K. Deasy, and S. Nic Chormaic, Nanostructured optical nanofibres for atom trapping, New. J. Phys. 16, 053052 (2014).
5. M. Sergides, V. G. Truong, and S. Nic Chormaic, Highly tunable plasmonic nanoring arrays for nanoparticle manipulation and detection. Nanotechnology, 27 (36): p. 365301 (2016).
Biography:
Viet Giang Truong, Ph.D., received his doctorate in optical materials from the University of Lyon I in 2004 and completed his postdoctoral training at IRCICA (Lille) for fibre laser applications in 2006.
From 2007-2011, he worked at INSA de Toulouse (Toulouse) and the ECE in NUS (Singapore) as a postdoctoral and a senior research fellow, where he focused his research topics on the III-V heterostructure semiconductors for spintronic devices. Dr. Truong joined the OIST Graduate University, Japan in 2012 as a Staff Scientist, group leader of the NanoBioOptics sub-group under the LMI Unit.
His current research is aimed to trap and manipulate particles at molecular levels using near-field optics of ultrathin fibres and plasmonic devices. Applications of such a compact device would be an important step towards the fabrication of an optical, label-free, non-destructive tool for molecular detection.''