Achromatic electromagnetic metasurface for generating a vortex wave with orbital angular momentum (OAM)

Area of Science:

• Optics and Photonics
• Electromagnetism
• Metamaterials

Background:

• Vortex waves carrying orbital angular momentum (OAM) offer an extra degree of freedom for applications like optical communication and imaging.
• Current methods for generating OAM at high frequencies face challenges including chromatic aberration and low efficiency.

Purpose of the Study:

• To design, fabricate, and demonstrate an azimuthally symmetric electromagnetic metasurface for efficient OAM vortex wave generation.
• To overcome the limitations of existing OAM generation techniques.

Main Methods:

• Design of an azimuthally symmetric electromagnetic metasurface.
• Utilizing the field equivalence principle for design methodology.
• Fabrication and experimental demonstration of the metasurface.

Main Results:

• Efficient conversion of circularly polarized incident waves to OAM-carrying vortex waves.
• Demonstration of wide-bandwidth performance.
• Experimental validation of the proposed OAM generation method.

Conclusions:

• The developed metasurface provides an effective and efficient approach for generating OAM vortex waves.
• The method exhibits comparative performance across a broad bandwidth, addressing previous limitations.