Theory of optical tweezing of dielectric microspheres in chiral host media and its applications
| Autor: | Ali, Rfaqat |
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| Přispěvatelé: | UNIVERSIDADE ESTADUAL DE CAMPINAS |
| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Repositório Institucional da Unicamp Universidade Estadual de Campinas (UNICAMP) instacron:UNICAMP Repositório da Produção Científica e Intelectual da Unicamp |
| Popis: | Agradecimentos: We thank Kainã Diniz, Bruno Pontes, Diney Ether and Nathan Viana for inspiring discussions. This work has been supported by the Brazilian agencies National Council for Scientific and Technological Development (CNPq), Coordination for the Improvement of Higher Education Personnel (CAPES), the National Institute of Science and Technology Complex Fluids (INCT-FCx), and the Research Foundations of the States of Minas Gerais (FAPEMIG), Rio de Janeiro (FAPERJ) and São Paulo (FAPESP) Abstract: We report for the first time the theory of optical tweezers of spherical dielectric particles embedded in a chiral medium. We develop a partial-wave (Mie) expansion to calculate the optical force acting on a dielectric microsphere illuminated by a circularly-polarized, highly focused laser beam. When choosing a polarization with the same handedness of the medium, the axial trap stability is improved, thus allowing for tweezing of high-refractive-index particles. When the particle is displaced off-axis by an external force, its equilibrium position is rotated around the optical axis by the mechanical effect of an optical torque. Both the optical torque and the angle of rotation are greatly enhanced in the presence of a chiral host medium when considering radii a few times larger than the wavelength. In this range, the angle of rotation depends strongly on the microsphere radius and the chirality parameter of the host medium, opening the way for a quantitative characterization of both parameters. Measurable angles are predicted even in the case of naturally occurring chiral solutes, allowing for a novel all-optical method to locally probe the chiral response at the nanoscale CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIG FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJ FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP Aberto |
| Databáze: | OpenAIRE |
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