All-optical Reconfiguration of Ultrafast Dichroism in Gold Metasurfaces

TL;DR

This paper demonstrates the all-optical reconfiguration of ultrafast dichroic responses in gold metasurfaces, enabling dynamic control of light polarization at femtosecond timescales through polarization-tuned pump pulses.

Contribution

It introduces a method to reconfigure the ultrafast dichroic response of gold metasurfaces using polarization control of pump pulses, combining theoretical prediction and experimental validation.

Findings

Ultrafast dichroic signals can be reconfigured by pump polarization.

The anisotropic response lasts less than a picosecond.

Full sign reversal of the optical response is achievable.

Abstract

Optical metasurfaces have come into the spotlight as a promising platform for light manipulation at the nanoscale, including ultrafast all-optical control via excitation with femtosecond laser pulses. Recently, dichroic metasurfaces have been exploited to modulate the polarization state of light with unprecedented speed. Here, we theoretically predict and experimentally demonstrate by pump-probe spectroscopy the capability to reconfigure the ultrafast dichroic signal of a gold metasurface by simply acting on the polarization of the pump pulse, which is shown to reshape the spatio-temporal distribution of the optical perturbation. The photoinduced anisotropic response, driven by out-of-equilibrium carriers and extinguished in a sub-picosecond temporal window, is readily controlled in intensity by tuning the polarization direction of the excitation up to a full sign reversal. This work proves that nonlinear metasurfaces offer the flexibility to tailor their ultrafast optical response in a fully all-optically reconfigurable platform.