Spin-to-orbital angular momentum conversion in dielectric metasurfaces.

Area of Science:

• Optics and Photonics
• Metamaterials
• Quantum Optics

Background:

• Vortex beams possess helical wavefronts and carry orbital angular momentum, crucial for applications like optical trapping and microscopy.
• Spin-to-orbital angular momentum conversion is a key method for generating vortex beams by utilizing geometrical phase.

Purpose of the Study:

• To demonstrate high-efficiency Spin-to-Orbital angular momentum Converters (SOCs) at visible wavelengths.
• To generate vortex beams with high and fractional topological charges.
• To achieve simultaneous generation of collinear helical beams with different orbital angular momenta.

Main Methods:

• Fabrication of dielectric metasurfaces for spin-to-orbital angular momentum conversion.
• Experimental generation and characterization of vortex beams with varying topological charges.
• Demonstration of simultaneous collinear helical beam generation.

Main Results:

• Achieved high-efficiency SOCs at visible wavelengths using dielectric metasurfaces.
• Successfully generated vortex beams with high and fractional topological charges.
• Demonstrated, for the first time, the simultaneous generation of collinear helical beams with arbitrary orbital angular momentum.

Conclusions:

• The developed dielectric metasurface SOCs offer a versatile and efficient method for creating vortex beams.
• This technology overcomes limitations of previous methods, like liquid crystal SOCs.
• The enhanced functionalities are expected to significantly expand the applications of vortex beams in various optical fields.