All-Optical Nonlinear Real and Fourier-Space Shaping with All-Dielectric Fano Resonant Metasurfaces

A main goal within the metasurface community is to develop dynamic, ultrafast tuning strategies for controlling beam profiles and directionality, especially in the ultraviolet regime. We present all-optical nonlinear beam shaping in both the beam profile and its angular distribution. We use a digital mirror device within a pump-probe setup that allows spatial pump patterns of a visible light pulse to spatiotemporally coincide with an infrared probe pulse onto an all-dielectric Fano resonant metasurface. The infrared pulse is tuned near the Fano resonance to generate strong third harmonics, and the pump pulse locally deactivates harmonic generation due to excitation of carriers that broaden and blue-shift the resonance. In Fourier space the spatially periodic pump patterns convolves with the third-harmonic diffraction pattern, which generates satellite orders that evidence coherent emission and directional control. This work enables ultrafast, precise control over harmonic beam profiles and directionality at the generation stage.