@phdthesis{oai:oist.repo.nii.ac.jp:00002959,
 author = {Bouloumis, Theodoros},
 month = {2023-06-06, 2023-06-06},
 note = {Optical tweezers have gained significant attention in many research fields as the only technique that provides immobilisation (trapping) and manipulation of micro- and nanoparticles. Moving from the conventional, free-space configuration to plasmonic structures using strong near-field forces, resulted in many more avenues towards the exploration of the nanoworld. However, with that, many challenges also appeared, as is usually the case when pushing the boundaries of the unknown. In this thesis, we focus on how to achieve an efficient trap for particles of just a few nanometres in size, such as colloidal quantum dots and gold nanoparticles. For this purpose, we investigate a novel metamaterial plasmonic design that exhibits a sharp plasmonic Fano resonance feature, which is very sensitive to refractive index changes of its environment. Three main projects are presented. In the first one, we work on the optimisation of the basic characteristics of the metamaterial, to ensure it has the desired plasmonic resonance and exhibits strong optical forces. We test its efficiency by trapping 20 nm polystyrene particles, yielding very high trap stiffness values. We also perform sequential trapping, revealing the ability of the structure for on-demand, particle nanopositioning. In the second project, we study the mechanism of self-induced back-action trapping. Under certain conditions, the particle can contribute to its own trap through an optomechanical coupling of its motion with the intracavity light intensity of the plasmonic nanocavity. For this experiment, gold nanoparticles were used and successfully trapped with extremely low laser intensities. Finally, the third project addresses the trapping of semiconductor quantum dots and custom-synthesised organic molecule nanoparticles that can be tuned to the desired size and emission wavelength ac-cording to the expected application. Photoluminescence measurements are also performed and an overall evaluation of the applicability and potential uses of these nanoparticles is discussed.},
 school = {Okinawa Institute of Science and Technology Graduate University},
 title = {強力なナノ粒子トラッピングの為のメタマテリアルプラズモン光ピンセット},
 year = {}
}