Theoretical study of optical vortex generation by dipolar particle array

Abstract

This research demonstrates generation of optical vortex in far field via excitation of an array of dipolar particles by linearly and circularly polarised incident light. Making use of Green's functions and taking into account particle-particle interactions, as well as using crucial approximations, we formulate a system that describes radiation of the system in the far field zone. The simulations show that indeed optical vortices can be found in the far zone for various cases. The radiation demonstrates a radially vanishing amplitude inwards, with zero around the axis in consideration, and the phase pattern suggests corkscrew like motion around the axis. In addition, when the topological charge of the system was varied, one could also observe the phenomenon of vortex splitting in various cases. Furthermore, generation of half-vortex, vortex with fractional charge, was also demonstrated using the same setup.