Optical ordering of nanoparticles trapped by Laguerre-Gaussian laser modes

In earlier work, it has been established that laser-induced coupling between a pair of nanoparticles can enable the generation of novel patterns, entirely determined and controlled by the frequency, intensity, and polarization of the optical input. Jn this paper, the detailed spatial disposition about the beam axis is determined for two-, three- and four-nanoparticle systems irradiated by a Laguerre-Gaussian (LG) laser mode. The range-dependent laser-induced energy shift is identified by the employment of a quantum electrodynamical description, calculations are performed to determine the distribution of absolute minima as a function of the topological charge, and the results are graphically displayed. This analysis illustrates a number of interesting features, including the fact that on increasing the LG beam's topological charge the particles increasingly cluster, i.e. the order of the structure is significantly raised - also the number of minima for which the particles can be trapped is enhanced. Finally, it is shown that similar principles apply to other kinds of radially structured optical modes.