Molding free-space light with guided wave-driven metasurfaces.

Area of Science:

• Optics and Photonics
• Metasurfaces
• Integrated Photonics

Background:

• Metasurfaces offer advanced light control but typically require external excitation, hindering on-chip integration.
• Integrated photonics allows dense component packing but has limited free-space light manipulation capabilities.

Purpose of the Study:

• To overcome the limitations of current metasurfaces and integrated photonics by merging their functionalities.
• To achieve on-chip control of guided waves to generate desired free-space optical modes.

Main Methods:

• Dressing metasurfaces directly onto optical waveguides.
• Utilizing metasurfaces to mold guided waves into complex free-space modes.
• Applying metasurfaces to active microring resonators to manipulate whispering gallery modes.

Main Results:

• Demonstrated molding of guided waves into arbitrary free-space modes, enabling functions like out-of-plane beam deflection and focusing.
• Achieved on-chip direct orbital angular momentum (OAM) lasing by breaking mode degeneracy in microring resonators.
• Successfully integrated metasurface functionalities with on-chip waveguides for enhanced light control.

Conclusions:

• This work presents a viable method for seamless control of light between integrated photonics and free-space platforms.
• Paves the way for multifunctional photonic integrated devices with agile free-space access.
• Enables diverse applications in communications, remote sensing, and display technologies.