Cross Diabolo Hollow Notch Nanotweezer for Optical Trapping and Manipulation

Plasmonic nanotweezer manipulates nanoparticles utilizing extraordinary electric field gradients and field enhancement originated from localized surface plasmon resonance. We proposed an ingenious silver-based cross diabolo hollow notch plasmonic nanotweezer. Additional edges at the center maximize the field enhancement caused by local surface plasmon hot spots. Moreover, the bottom Ag film’s screening effect significantly increases the field intensity near the trapping targets. The subsequent field gradient remarkably enhances the trapping capability of the design in comparison to conventional plasmonic tweezers. We carried out a comprehensive analysis of structural design optimization to reduce power consumption and significantly improve optical trapping properties. The proposed Ag CDHN nanotweezer can trap a polystyrene sphere of 30 nm diameter at a minimum beam intensity of 2.66 mW/
$\mu$
m
$^{2}$
and trapping force of 2.14 nN/(W.
$\mu$
m
$^{-2}$
) towards the nanostructure. In comparison to previously reported nanotweezers, the proposed nanotweezer demonstrated a few-order increase in trapping stiffness and a few times decrease in power consumption. We also evaluated its capacity to trap polystyrene spheres of varying diameters. Our proposed design and analysis will be beneficial in realizing effective nanotweezer for nanoparticle manipulation as well as nanostructure fabrication.