We numerically show that both repulsive and attractive (bipolar) optical forces can be exerted on a dielectric or metallic cylindrical nanoparticle by a totally internal refracted wave. This requires that the particles possesses either a whispering gallery (WG) resonance or a localized surface plasmon (LSP) resonance. We further explore the force spectrum that is governed by competition between the separation-dependent resonant Q factor and the coupling strength of the nanoparticle to the evanescent wave. In spite of a much smaller Q of the LSP as compare to the WG resonances, the metallic particle gains much stronger trapping force.
© 2010 Optical Society of America
Lasers and Laser Optics
Original Manuscript: October 28, 2009
Revised Manuscript: February 8, 2010
Manuscript Accepted: February 16, 2010
Published: March 23, 2010
J. J. Xiao, H. H. Zheng, Y. X. Sun, and Y. Yao, "Bipolar optical forces on dielectric and metallic nanoparticles by evanescent wave," Opt. Lett. 35, 962-964 (2010)