Photonic spin Hall effect based on broadband high-efficiency reflective metasurfaces

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Generating broadband, high-efficiency circularly polarized (CP) light is challenging in traditional chiroptical spectroscopy.
• Metasurfaces offer unique optical properties through subwavelength nanostructures.

Purpose of the Study:

• To design reflective Pancharatnam-Berry metasurfaces for broadband, high-efficiency generation of left-circular polarization (LCP) and right-circular polarization (RCP) light.
• To demonstrate a broadband, high-efficiency reflective vortex beam generator for RCP light.
• To enhance the intensity of generated vortex beams through focusing.

Main Methods:

• Introduction of a broadband (∼1 µm) high-efficiency half-wave plate in the near-infrared (NIR) region.
• Design of reflective Pancharatnam-Berry metasurfaces.
• Development of a metasurface-based reflective vortex beam generator.

Main Results:

• Achieved high-efficiency (average >90%) generation of LCP and RCP light over a broadband (∼900 nm) in the NIR region.
• Demonstrated a broadband, high-efficiency reflective vortex beam generator for RCP light.
• Successfully focused the generated vortex beam to a point, increasing its intensity.

Conclusions:

• The designed metasurfaces provide an effective method for generating broadband, high-efficiency CP light.
• This work advances capabilities in complex chiroptical spectroscopy and optical beam manipulation.
• The metasurface approach enables efficient generation and focusing of structured light in the NIR.