Dynamically controllable plasmonic tweezers using C-shaped nano-engravings

A near-field optical trapping scheme using plasmonic C-shaped nano-engraving is presented. Utilizing the polarization sensitivity of the C-structure, a mechanism is proposed for dynamically controlling the electric field, the associated trapping force, and the plasmonic heating. Electromagnetic analysis and particle dynamics simulations are performed to verify the viability of the approach. The designed structure is fabricated and experimentally tested. Polarization control of the excitation light is achieved through the use of a half-wave plate. Experimental results are presented that show the functioning implementation of the dynamically adjustable plasmonic tweezers. The dynamic controllability can allow trapping to be maintained with lower field strengths, which reduces photo-thermal effects. Thus, the probability of thermal damage can be reduced when handling sensitive specimens.