All-Optically Reconfigurable Plasmonic Metagrating for Ultrafast Diffraction Management.

Area of Science:

• Ultrafast nanophotonics
• Plasmonics
• Materials science

Background:

• Hot-electron dynamics in nanostructured materials under femtosecond (fs) laser pulses are crucial for ultrafast nanophotonics.
• Current models often assume uniform photogenerated carrier distribution, limiting understanding of nanoscale phenomena.

Purpose of the Study:

• To theoretically investigate the impact of inhomogeneous hot-electron evolution on ultrafast diffraction.
• To design a nanostructured material for controlled manipulation of light diffraction.

Main Methods:

• Theoretical modeling of hot-electron dynamics in plasmonic nanostructures.
• Design of a highly symmetric plasmonic metagrating.
• Simulation of transient symmetry breaking and diffraction order power imbalance.

Main Results:

• Demonstrated that nanoscale inhomogeneous hot-electron evolution enables ultrafast diffraction management.
• Designed a plasmonic metagrating exhibiting transient symmetry breaking driven by hot electrons.
• Calculated a >20% power imbalance between symmetrical diffraction orders at moderate laser fluence (~2 mJ/cm^2).

Conclusions:

• Inhomogeneous hot-electron dynamics offer new possibilities for ultrafast diffraction control.
• Metagrating geometry can tune the recovery time of symmetry, achieving values as low as 2 ps for connected configurations.