Synergistic effect of Fano resonance and optical nonlinearity in laser trapping of silver nanoparticles

Abstract

Optical trapping efficiency for silver nanoparticles is theoretically estimated using dipole approximation and generalized Lorenz-Mie theory, including higher-order optical nonlinear effects. Here, we show a reversal in asymmetry of axial trapping potential due to Fano resonance is observed, along with a splitting of trapping potential well due to optical nonlinearity. Further, it is shown that there exists a limit for particle size beyond which the particle cannot be trapped and how this limit can be extended by harnessing optical nonlinearity under femtosecond pulsed excitation