摘要
Lateral optical forces induced by linearly polarized laser beams have been predicted to deflect dipolar particles with opposite chiralities toward opposite transversal directions.These“chirality-dependent”forces can offer new possibilities for passive all-optical enantioselective sorting of chiral particles,which is essential to the nanoscience and drug industries.However,previous chiral sorting experiments focused on large particles with diameters in the geometrical-optics regime.Here,we demonstrate,for the first time,the robust sorting of Mie(size~wavelength)chiral particles with different handedness at an air–water interface using optical lateral forces induced by a single linearly polarized laser beam.The nontrivial physical interactions underlying these chirality-dependent forces distinctly differ from those predicted for dipolar or geometrical-optics particles.The lateral forces emerge from a complex interplay between the light polarization,lateral momentum enhancement,and out-of-plane light refraction at the particle-water interface.The sign of the lateral force could be reversed by changing the particle size,incident angle,and polarization of the obliquely incident light.
基金
the financial support from the Ministry of Education,Singapore(Project No.R-263-000-D11-114)
from the National Research Foundation,Prime Minister’s Office,Singapore under its Competitive Research Program(CRP award NRFCRP15-2015-03 and NRFCRP15-2015-04)
the Singapore National Research Foundation under the Competitive Research Program(NRF-CRP13-2014-01)
the Incentive for Research&Innovation Scheme(1102-IRIS-05-04)administered by PUB
the Fundamental Research Funds for the Central Universities(DUT19RC(3)046)
supported by the Spanish Ministerio de Economia y Competitividad(MICINN)and European Regional Development Fund(ERDF)Project FIS2015-69295-C3-3-P
the Basque Dep.de Educacion Project PI-2016-1-0041.
