Plasmonic Trapping In Periodic Gold Polygon Tetramers

Metallic nanostructures surface plasmon(Surface Plasmon Polaritons, SPPs) is a collective excitation of electrons, similar to the oscillatory behavior of waves. Using its nature of generateing metal surface local field enhancement and breaking the diffraction limit that can be applied to optical trapping, which may be called surface plasmons optical trapping. Plasmon optical trapping based on localized surface contributed greatly to the development of optical trapping, optical trapping cross from microscale to nanoscale. Localized surface of metallic nanostructures electromagnetic enhancement greatly depends on incident wave metal nanostructures, further affecting its application in optical capture.This paper mainly studies the different metal nanostructures produced a different surface plasmon local electromagnetic field enhancement, and the impact of different metal nanostructure on optical capture, metallic nanostructures include gold quadrilateral tetramer, gold pentagon tetramer, gold hexagon tetramer and gold triangle tetramer and golden triangle windmill structure. While further study the impact of different wavelengths and different polarization incident on the surface plasmon electromagnetic local field enhancement and optical capture. The main study way in this paper is FDTD method(finite-difference time-domain(FDTD) method), using numerical simulation to accurately calculate the electromagnetic field distribution of the metal surface and the surrounding space, transmission spectrum, reflection spectrum, absorption spectrum, etc. Optical force and potential associated with optical trapping can be obtained by further data analysis.Metal surface electromagnetic field distribution and the corresponding optical power obtained by numerical simulation show the side of the metal nano-polymer greatly affect small spherical media capture efficiency. The localized surface plasmon resonance enhanced of quadrilateral tetramer is the most obvious, capturing ability of small dielectric sphere relative to the pentagonal and hexagonal tetramer tetramer is stronger. Media sphere diameter also affects the situation which is captured in a different metal nanostructures. The ultimate realization of a certain wavelength in a certain position for a certain selective capture beads, which can be further applied to tiny nanospheres control in solution. You can also change the polarization direction of the incident light to change the trapping position of the triangle nano tetramer. Also, using non-symmetry triangular windmill structure response to left and right spin circularly polarized light to manipulate particles. Compared with traditional optical trapping, surface plasmonic optical trapping breaking the diffraction limit. Using different metallic nanostructures to achieve small particles' selective manipulation, which has great significance in the physical, chemical and biological medicine.