Dynamic Focusing with High-Quality-Factor Metalenses.

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Metasurface lenses offer ultrathin light focusing but suffer from limited dynamic tunability due to weak light-matter interactions.
• Existing metasurface designs struggle to achieve significant modulation of optical properties.

Purpose of the Study:

• To design and demonstrate submicron-thick, ultrahigh quality factor (high-Q) metalenses for dynamic modulation of focal length and intensity.
• To explore the use of nonlinear optical effects for active control of metalens performance.

Main Methods:

• Utilized full-field simulations to design metalenses with periodic perturbations in constituent silicon (Si) nanoantennas.
• Achieved quality factors exceeding 5000 by incorporating subtle perturbations.
• Investigated the nonlinear Kerr effect for dynamic modulation of focal properties.

Main Results:

• Demonstrated dynamic focal length modulation from 4 to 6.5 μm.
• Observed a decrease in focal intensity by half with increasing input intensity (0.1 to 1 mW/μm²).
• Showcased the embedding of multiple high-Q resonances through strategic perturbation placement.

Conclusions:

• The high-Q metalens design, with Q-factors two orders of magnitude higher than current designs, enables dynamic control of light.
• This work lays the foundation for reconfigurable, multiplexed, and hyperspectral metasurface imaging platforms.