Theory for optical assembling of anisotropic nanoparticles by tailored light fields under thermal fluctuations

Abstract

In order to evaluate the assembling processes of arbitrary-shaped nanoparticles (NPs) by the irradiation of a tailored laser beam under thermal fluctuations, we have developed a “Light-induced-force Nano Metropolis Method (LNMM)” as a new theoretical method based on the stochastic algorithm in the energy region and the general formula of light-induced force. By using LNMM, we have investigated the change of configurations of silver NPs with anisotropic shapes under the irradiation of laser beams with various polarizations and intensity distributions (Gaussian beam and axially-symmetric vector beams) in an aqueous solution at room temperature. As a result, it has been clarified that silver NPs can be selectively arranged into a characteristic spatial configuration reflecting the properties of an irradiated laser beam (wavelength, intensity distribution, and polarization distribution), and that the assembled structures possess broadband spectra and exhibit a strong optical response to the irradiated laser beam through the optimization with the help of fluctuations.