Speaker
Description
The rapid evolution of photonics has enabled unprecedented control over light-matter interactions on the picosecond time scale and even faster, with plasmonic metasurfaces (MSs) emerging as key components in next-generation optoelectronic devices. MSs composed of periodic gold nanostructures patterned on silicon substrates can offer both localized surface plasmon resonance (LSPR) and all-optical control. While the LSPR amplifies the light-matter interaction1, the silicon substrate facilitates rapid modulation of optical properties through field-enhanced impact ionization. Accelerated free carriers boost the generation of electron-hole pairs and dynamically alter the material’s optical response.2
When irradiated with intense mid-infrared pulses from a free-electron laser (FELIX), the carrier concentration in silicon undergoes significant changes, which can be tracked using time-resolved pump-probe spectroscopy. By modifying the configuration of MSs, namely single-type and coupled-type (Fig. 1), different mechanisms are excited, revealing the interplay between local field enhancement, carrier dynamics, and electromagnetic near-field coupling. These insights uncover novel pathways for ultrafast energy transfer in coupled plasmonic systems, offering a foundation for actively tunable resonant metasurfaces and the development of ultrafast all-optical technologies.
