Roubaud Gauthier, Bondareff Pierre, Volpe Giorgio, Gigan Sylvain, Bidault Sébastien, Grésillon Samuel
Institut Langevin, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 1 rue Jussieu, F-75005 Paris, France.
Laboratoire Kastler Brossel, Sorbonne Université, École Normale Supérieure-PSL University, CNRS, Collège de France, 24 rue Lhomond, 75005 Paris, France.
Nano Lett. 2020 May 13;20(5):3291-3298. doi: 10.1021/acs.nanolett.0c00089. Epub 2020 Apr 8.
We demonstrate the local optimization of nonlinear luminescence from disordered gold metasurfaces by shaping the phase of 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 subwavelength electric fields. In practice, the increase in nonlinear luminescence is strongly sensitive to both the nanometer-scale morphology and the level of structural complexity of the gold metasurface. We typically observe a 2 orders 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.
我们通过对飞秒激发相位进行整形，展示了无序金超表面非线性发光的局部优化。这一过程是通过对样品表面离域的等离子体模式进行远场波前控制实现的，从而导致亚波长电场的相干增强。实际上，非线性发光的增加对金超表面的纳米级形态和结构复杂程度都非常敏感。与随机激发波前相比，对于优化后的激发波前，我们通常观察到发光信号增强了两个数量级。这些结果表明，由随机耦合的等离子体谐振器构成的无序超表面，与波前整形一起，如何提供了众多自由度来编程局部优化的非线性响应和光学热点。
