Optical fiber tip tweezers, a complementary approach for nanoparticle trapping

Nanoparticles of different compositions, sizes, and shapes are elaborated and trapped in a reproducible and stable manner using our optical fiber tip tweezers. Here we report trapping of spherical YAG: Ce³⁺ particles of 300 and 60 nm diameters and of NaYF⁴: Er^{3 +}, Yb^{3 +} nanorods of lengths from 640 nm to 1.9 μm. The properties of the tweezers are analyzed by video observations using Boltzmann statistics and power spectra analysis. Efficient trapping is found for the spherical particles and the small nanorods, whereas the large nanorods are efficiently trapped with only one fiber tip. The optical emission of a trapped nanorod completes the experimental results. Force calculations using the exact Maxwell stress tensor formalism are conducted to explain the experimental observations.