Generation of 3D quasi-spherical multi-focus arrays and optical rings using orthogonally superimposed dipole antenna arrays

Abstract

This paper proposes a novel method to generate a three-dimensional (3D) quasi-spherical focal point with high longitudinal and transverse resolution in a 4Pi focusing system based on the radiation pattern of the orthogonally superimposed dipole antenna. In this paper, we present generated 3D quasi-spherical multi-focus arrays that are controllable and uniformly distributed and optical rings from the radiation patterns of antenna arrays in different configurations. The results showed that the generated focal point is smaller longitudinally (0.31λ) than transversely (0.41λ). This focal point has the smallest volume (∼0.0273λ 3) found. Moreover, it is highly homogeneous and has a small side lobe. The polarization at the center of the focal point is purely circular. The resulting 3D focal fields can be easily tailored by adjusting the modulation parameters of the orthogonally superimposed dipole arrays. Manipulating 3D optical focal fields with pre-defined characteristics of quasi-spherical focal points has a high degree of freedom. Many potential applications exist in arbitrarily oriented particle capture and guidance, micromanipulation, optical capture, and 3D optical data storage.