Far-field Wavefront Control of Nonlinear Luminescence in Disordered Gold Metasurfaces

Gauthier Roubaud, Pierre Bondareff, Giorgio Volpe, Sylvain Gigan, Sébastien Bidault & Samuel Grésillon

We demonstrate the local optimization of nonlinear luminescence from disordered gold metasurfaces by shaping the phase of a femtosecond excitation. This process is enabled by the far-field wavefront control of plasmonic modes delocalized over the sample surface, leading to a coherent enhancement of sub-wavelength electric fields. In practice, the increase in nonlinear luminescence is strongly sensitive to both the nanometer-scale morphology and to the level of structural complexity of the gold metasurface. We typically observe a two-order of magnitude enhancement of the luminescence signal for an optimized excitation wavefront compared to a random one. These results demonstrate how disordered metasurfaces made of randomly coupled plasmonic resonators, together with wavefront shaping, provide numerous degrees of freedom to program locally optimized nonlinear responses and optical hotspots.