Optical reflective metasurfaces enable spin-decoupled OAM and focusing

Area of Science:

• Optics and Photonics
• Materials Science
• Electromagnetics

Background:

• Orbital angular momentum (OAM) offers unique properties for wireless communication and information capacity.
• Beam focusing is crucial for applications like super-resolution microscopy and optical integration.
• Plasmonic metasurfaces provide powerful electromagnetic wave modulation capabilities, with a demand for diversified functionalities.

Purpose of the Study:

• To develop multifunctional plasmonic metasurfaces capable of integrating diverse electromagnetic wave modulation functions.
• To demonstrate independent phase control for left-handed circular polarization (LCP) and right-handed circular polarization (RCP) waves.
• To present novel designs for single-device multi-functionality in electromagnetic modulation.

Main Methods:

• Utilizing geometric phase and propagation phase by fine-tuning meta-atom dimensions and orientation.
• Designing three distinct plasmonic metasurfaces, each exhibiting multiple functionalities.
• Employing gradient sequences for anomalous OAM reflection and computational focusing, and the addition theorem for combined functionalities.

Main Results:

• Achieved normal reflection of OAM and beam focusing on a single metasurface.
• Demonstrated anomalous reflection of OAM and arbitrary point focusing.
• Implemented combined functionalities including normal and inclined output beams using the addition theorem.
• Successfully integrated multiple functions onto single plasmonic metasurface devices.

Conclusions:

• The developed plasmonic metasurfaces offer novel approaches for integrating multiple electromagnetic modulation functions.
• This work advances the design of multifunctional flat optical devices.
• The findings have implications for integrated optics, advanced imaging, and wireless communication systems.