6533b862fe1ef96bd12c7770

RESEARCH PRODUCT

Optofluidic taming of a colloidal dimer with a silicon nanocavity

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International audience; We report here the optical trapping of a heterogeneous colloidal dimer above a photonic crystal nanocavity used as an on-chip optical tweezer. The trapped dimer consists of a cluster of two dielectric microbeads of different sizes linked by van der Waals forces. The smallest bead, 1 μm in diameter, is observed to be preferentially trapped by the nanotweezer, leaving the second bead untrapped. The rotational nature of the trapped dimer Brownian motion is first evidenced. Then, in the presence of a fluid flow, control of its orientation and rotation is achieved. The whole system is found to show high rotational degrees of freedom, thereby acting as an effective flow-sensitive microscopic optical ball joint.C.P., C.R., B.C., and F.d.F. acknowledge the regional council of Burgundy for financial funding in the framework of the PHOTCOM project. This project has been performed in cooperation with the Labex ACTION program (Contract No. ANR-11-LABX-0001-01)