Design of laser trap using plasmonic optical nano antenna and visible laser

In this paper, a laser trap with the ability to generate pico-Newtonian optical force is designed using optical nano-antenna and visible-range laser based on localized surface plasmon resonance (LSPR). The Maxwell equations of this system are solved numerically by the time domain finite difference (FDTD) method. Then, we investigate the effect of circular surface grooves at the tip of this nano-antenna on the optical force of this laser trap. The simulation results showed that the maximum of electric field intensity for the non-grooved and grooved nano-antenna occurred at the wavelengths of 533 and 608 nm, respectively, and also the groove on the tip of nano-antenna increases electric field intensity. Also, the optical force applied to the 10 nm spherical nanoparticles at 3 nm from the nano-antenna tip was obtained 0.11 pN/W and 0.55 pN/W, respectively. That is, firstly, this plasmonic optical nano-antenna can be used as a laser trap for metallic nanoparticles. Secondly, creating a surface groove on the tip of this nano-antenna increases the optical force and consequently efficiency of the laser trap about 5 times.