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

## TL;DR

This paper introduces a method to control light beams using all-dielectric metasurfaces, enabling fast and precise shaping of light in both space and direction.

## Contribution

The novel use of all-optical nonlinear shaping with Fano resonant metasurfaces for ultrafast control of harmonic beam profiles and directionality.

## Key findings

- Spatial pump patterns convolve with third-harmonic diffraction to generate satellite orders.
- Ultrafast control of harmonic beam profiles and directionality is achieved at the generation stage.

## Abstract

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.