Generation of hallow vector beam by high-order cylindrical vector beams

TL;DR

This paper presents a novel method for generating hollow beams using higher-order cylindrical vector modes, enabling precise control over beam properties for advanced optical applications like trapping and information encoding.

Contribution

The study introduces a new technique combining a diffractive optical element and vector diffraction theory to produce tunable hollow beams with consistent dark cores across various modes.

Findings

Hollow beams can be generated using higher-order cylindrical vector modes.

The method maintains a uniform dark core size after focusing.

The high intensity ring width can be tuned by adjusting the lens NA.

Abstract

We propose a method for generating hollow beams using higher-order cylindrical vector modes of the form R-TEMpl, where the radial index p is varied from 1 to 3 while the azimuthal index is fixed at l = 1. It is found that this scheme performs identically under incident illumination with either radial or azimuthal polarization. For this purpose, we use a focusing lens in combination with a diffractive optical element formed by a computer-generated hologram containing multiple alternate opaque and transparent regions. Based on vector diffraction theory, our analysis shows that the multi-zone amplitude mask redistributes the beam energy, thereby leading to the formation of a hollow beam. The proposed method provides control over the beam width which maintains a uniform dark core size after focusing through the various NA lens across all the higher order modes. Further the width of high intensity ring can be tuned by varying the NA of the focusing lens. This study shows that the proposed method is well suited for trapping particles or atoms while avoiding exposure to high central intensity, enabling improved contrast and resolution, facilitating ring-shaped ablation or heating, guiding atoms through dark regions to minimize thermal effects, and supporting information encoding using orbital angular momentum and other advanced optical applications.