Creating perfect composite vortex beams with a single all-dielectric geometric metasurface

Area of Science:

• Optics and Photonics
• Metamaterials
• Nanotechnology

Background:

• Optical vortex beams, particularly perfect vortex beams (PVBs), are vital for applications leveraging orbital angular momentum.
• PVBs offer a topological charge (TC)-irrelevant intensity profile but suffer from morphological singularities and implementation complexity, limiting multiplexing capabilities.

Purpose of the Study:

• To introduce a novel perfect composite vortex beam (PCVB) that overcomes the limitations of traditional PVBs.
• To demonstrate a method for generating PCVBs with TC-correlated rosette-like intensity patterns using a single all-dielectric geometric metasurface.

Main Methods:

• Numerical simulations were employed to demonstrate the broadband generation of PCVBs with tunable TCs, sizes, and rotation angles.
• The study involved designing and simulating an all-dielectric geometric metasurface for direct PCVB generation.

Main Results:

• A novel PCVB with a rosette-like intensity pattern, directly correlated with the topological charge (TC), was successfully proposed and simulated.
• Broadband generation of PCVBs was achieved, showcasing tunability in TC, size, and rotation angle.
• Coaxial arrays of PCVBs were demonstrated, and their optical angular force for nanoparticle manipulation was detected.

Conclusions:

• The proposed PCVB offers a new degree of freedom for optical multiplexing by overcoming the limitations of conventional PVBs.
• The direct generation using a single metasurface simplifies implementation compared to bulky optical systems.
• PCVB technology shows significant potential for advancements in optical communication, information processing, and optical manipulation.