title: Optical trapping of NaYF4:Er3+,Yb3+ upconverting fluorescent nanoparticles.
abstract: We report on the first experimental observation of stable optical trapping of dielectric NaYF4:Er(3+),Yb(3+) upconverting fluorescent nanoparticles (~26 nm in diameter) using a continuous wave 980 nm single-beam laser. The laser serves both to optically trap and to excite visible luminescence from the nanoparticles. Sequential loading of individual nanoparticles into the trap is observed from the analysis of the emitted luminescence. We demonstrate that the trapping strength and the number of individual nanoparticles trapped are dictated by both the laser power and nanoparticle density. The possible contribution of thermal effects has been investigated by performing trapping experiment in both heavy water and into distilled water. For the case of heavy water, thermal gradients are negligible and optical forces dominate the trap loading behaviour. The results provide a promising path towards real three dimensional manipulation of single NaYF4:Er(3+),Yb(3+) nanoparticles for precise fluorescence sensing in biophotonics experiments.
authors.affiliation: Fluorescence Imaging Group, Departamento de Física de Materiales, C-IV, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente 7, Madrid, 28049, Spain. daniel.jaque@uam.es.
authors.forename: P
authors.initials: P
authors.lastname: Haro-González
authors.forename: B
authors.initials: B
authors.lastname: del Rosal
authors.forename: L M
authors.initials: LM
authors.lastname: Maestro
authors.forename: E Martín
authors.initials: EM
authors.lastname: Rodríguez
authors.forename: R
authors.initials: R
authors.lastname: Naccache
authors.forename: J A
authors.initials: JA
authors.lastname: Capobianco
authors.forename: K
authors.initials: K
authors.lastname: Dholakia
authors.forename: J García
authors.initials: JG
authors.lastname: Solé
authors.forename: D
authors.initials: D
authors.lastname: Jaque