Externally Driven Nonlinear Time-Variant Metasurfaces

Resonant photonic nanostructures exhibiting enhanced nonlinear response and efficient frequency conversion are an emergent platform in nonlinear optics. High-index semiconductor metasurfaces with rapidly tuned high-quality-factor (high-Q) resonances enable a novel class of time-variant metasurfaces, which expands the toolbox of color management at the nanoscale. Here, we report on the dynamic control of the nonlinear optical response in time-variant semiconductor metasurfaces supporting high-Q resonances in the near-infrared spectral range. Germanium metasurfaces reveal frequency conversion of the fundamental beam and blue-shift of 10 nm (3.05 omega) and 40% broadening in the third-harmonic spectrum due to a subpicosecond-scale time-variant refractive index. A time-dependent coupled-mode theory, in qualitative agreement with the experimental data, validated the time-variant nature of the system. Our findings expand the scope of time-variant metasurfaces and may serve as base for the next generation of nanoscale pulse shapers, optical switches, and light sources.

Automated summary

This study reports the dynamic control of the nonlinear optical response in time-variant semiconductor metasurfaces supporting high-Q resonances in the near-infrared spectral range, and validates the time-variant nature of the system.