Externally Driven Nonlinear Time-Variant Metasurfaces

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