Spin-controlled twisted laser beams: intra-cavity multi-tasking geometric phase metasurfaces

Area of Science:

• Optics and Photonics
• Metamaterials
• Laser Physics

Background:

• Generating tailored light beams with specific properties like spin-dependence and topology is crucial for advanced optical applications.
• Traditional methods for creating such beams can be complex and inefficient.

Purpose of the Study:

• To incorporate novel multi-tasking geometric phase metasurfaces into a laser cavity.
• To efficiently generate spin-dependent twisted light beams with controllable topologies.
• To explore new nanophotonic functionalities and light-matter interactions.

Main Methods:

• Modified degenerate cavity laser incorporating geometric phase metasurfaces as output couplers.
• Utilized shared-aperture metasurfaces to form multiple harmonic scalar vortex laser beams.
• Employed an interleaving approach with geometric phase profiles for diverse wave functions.
• Generated vectorial vortices by superposing scalar vortices with opposite topological charges and spin states.
• Incorporated harmonic response metasurfaces to produce partially coherent vortices.

Main Results:

• Successfully generated spin-dependent twisted light beams with different topologies.
• Produced multiple harmonic scalar vortex laser beams using shared-aperture metasurfaces.
• Achieved a variety of distinct wave functions through interleaved metasurfaces.
• Demonstrated the generation of vectorial vortices and partially coherent vortices.

Conclusions:

• Metasurface integration into laser cavities offers a powerful platform for generating complex light beams.
• This approach enables novel nanophotonic functionalities and enhanced light-matter interactions.
• Paves the way for advanced light manipulation techniques and applications.