Angular dispersion-enabled dynamic metasurface for tunable reflective focusing

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Active metasurfaces offer compact alternatives to bulky optical systems.
• Controlling wavefront modulation is key for advanced optical functionalities.

Purpose of the Study:

• To introduce incident angle as a novel control parameter for dielectric metasurfaces.
• To demonstrate a dynamic metalens with angle-tunable focal length.

Main Methods:

• Utilizing angular dispersion of Mie resonances in silicon ring disks.
• Numerically simulating a dielectric metasurface with angle-dependent phase modulation.
• Balancing reflectivity and phase for efficient focusing.

Main Results:

• Demonstrated a metalens with focal lengths of 10 µm (15° incident angle) and 20 µm (20° incident angle).
• Achieved focusing efficiencies of 13.5% and 18.13% respectively.
• Showcased continuous focal tuning via progressive incident angle adjustments.

Conclusions:

• Incident angle provides a new degree of freedom for dynamic metasurface control.
• The developed approach facilitates the creation of portable, tunable optical systems.
• This research advances the development of compact zoom lenses.