Bragg-Berry mirrors: reflective broadband q-plates

Area of Science:

• Photonics
• Optical Physics
• Materials Science

Background:

• Optical vortices are crucial for optical manipulation and communication.
• Generating optical vortices efficiently, especially broadband, remains a challenge.
• Chiral materials offer unique optical properties for light manipulation.

Purpose of the Study:

• To experimentally demonstrate broadband generation of optical vortices using flat mirrors.
• To explore the underlying physics of spin-orbit coupling in chiral media for vortex generation.
• To develop novel optical elements for spin-orbit photonic applications.

Main Methods:

• Utilizing spatially patterned chiral liquid crystal films.
• Leveraging the circular Bragg reflection phenomenon and geometric Berry phase.
• Investigating reflective optical vortex generation from various paraxial light beams.

Main Results:

• Achieved broadband generation of optical vortices upon reflection from flat mirrors.
• Demonstrated the effect across the visible spectrum, highlighting intrinsic broadband capability.
• Confirmed the generation of optical phase singularities from both diffractive and nondiffractive beams.

Conclusions:

• The developed flat mirrors enable robust, broadband optical vortex generation.
• The method circumvents birefringent retardation requirements, simplifying device design.
• This work advances the development of optical elements for spin-orbit photonic technologies.