Generation of uniform three-dimensional optical chain with controllable characteristics

Abstract

An approach is proposed for the construction of a uniform three-dimensional (3D) interconnected optical chain with variable length, prescribed spot number and spacing along the optical axis. This can be achieved in a 4Pi focusing system through reversing the radiation patterns from a uniform magnetic current line source in combination with an electric current line source with a cosine-squared taper. The required pupil plane illumination for generating the desired uniform 3D optical chain near the focus of high NA lens can be found analytically. It is found that the number of dark spots only depends on the parameter N related to magnetic current periodic distribution, while the length of optical chain and the interval between two adjacent spots approximately equal to the length L of line source and L/N, respectively. Numerical results demonstrate that the characteristics of the constructed optical chain can be controlled purposely through proper choices of the parameters N and L. The present work may find valuable applications in optical microscopy as well as multi-particle trapping, delivery, and manipulation.