Ultrafast Optically Tunable GaAs Metasurfaces for Analog Image Processing.

Optical metasurfaces offer unprecedented potential for miniaturizing conventional bulk optics into compact, energy-efficient devices suitable for advanced edge computing applications. However, current implementations lack the dynamic tunability essential for real-time optical processing functions. Here, we numerically demonstrate a gallium arsenide metasurface that achieves subpicosecond switching between dual complex-valued transfer functions through ultrafast photoinduced carrier modulation. Our device exploits specially designed Mie-resonant nanoantennas for nonuniform amplitude and phase profile change under pump pulses with typical energies about 4.8 nJ. The metasurface enables real-time Fourier filtering with switching frequency exceeding 100 GHz, providing a pathway to ultrafast neuromorphic vision sensors and live image processing applications.