Trapping of rare earth-doped nanorods using quasi Bessel beam optical fiber tweezers

We demonstrate optical trapping of rare earth-doped NaYF 4 :Er/Yb nanorods of high aspect ratio (length 1.47 μ m and diameter 140 nm) using a quasi Bessel beam (QBB) generated by positive axicon optical fiber tips. Propulsion or trapping of the nanorods is demonstrated using either single or dual fiber nano-tip geometries. The optical force exerted on the trapped nanorods, their velocities, and their positions have been analyzed. We determine the trap stiffness for a single nanorod to be 0.12 pN/ μ m (0.003 pN/ μ m) by power spectrum analysis and 0.13 pN/ μ m (0.015 pN/ μ m) by Boltzmann statistics in the direction perpendicular to (along) the fiber axes for an average optical power of 34 mW. The experiments illustrate the advantage of using a QBB for multiple nanorod trapping over a large distance of up to 30 μ m.