Reconfigurable terahertz metasurfaces coherently controlled by wavelength-scale-structured light

Area of Science:

• Optics and Photonics
• Materials Science
• Condensed Matter Physics

Background:

• Metasurfaces traditionally rely on lithographically defined nanostructures for light-matter interaction.
• Their operation is dictated by the collective electric polarization response of these structures.
• The link between electric polarization and current density offers an alternative approach using current elements.

Purpose of the Study:

• To demonstrate a novel method for creating metasurfaces using structured light instead of structured materials.
• To enable the dynamic reconfiguration of metasurface properties.
• To generate tunable terahertz (THz) radiation.

Main Methods:

• Utilizing coherent control to imprint structural information from light onto transient currents within a semiconductor.
• Employing a spatial light modulator (SLM) to precisely control the spatial structure of these transient currents.
• Leveraging the generated transient currents as sources for THz radiation.

Main Results:

• Successfully realized metasurfaces by structuring light, transferring spatial information to transient currents.
• Achieved control over the spatial structure of THz radiation with subwavelength resolution ($$).
• Demonstrated the reconfigurability of the metasurface through SLM control at 1 THz.

Conclusions:

• This approach decouples metasurface functionality from fixed nanostructures, offering unprecedented flexibility.
• The use of mature SLM technology combined with light-induced currents paves the way for highly adaptable optical devices.
• This work opens new avenues for dynamic control of light-matter interactions at the subwavelength scale.