Low-Power Far Field Nanonewton Optical Force Trapping Based on Far-Field Nanofocusing Plasmonic Lens

Pengfei Cao, and Lin Cheng

In this article, we study the far-field trapping behavior of dielectric nanospheres with diameter of 200 nm by utilizing a plasmon enhanced far-field nanofocusing lens. Based on our high effects nanofocusing circular plasmonic lens, such a far-field plasmonic trap is constituted by illuminating with a laser to form a sharper focus (subwavelength) due to a constructive interference of cylindrical surface plasmon wave. The nanoparticles can be steadily trapped in the far-field focal region (4.4λ) with an optical force to nanonewton (−4.76 nN) order, and the required optical power is less than 0.5W. Compared with other surface plasmon tweezers, the proposed far-field plasmonic tweezers can not only avoid physical contact with the trapped particles to prevent contamination and reduce thermal damage effects due to metal absorption, but also enable the easy trapping and manipulation of nanosize dielectric particles owing to nanonewton scale forces.

DOI