Title: Light-controlled disorder-engineering for functional optical metasurfaces

Abstract

Optical metasurfaces address a plethora of applications in planar optics, as they enable precise control of the phase, amplitude, and polarization of light at nanoscale interaction lengths. However, their implementation often requires surface nanostructuring based on complex design and top-down fabrication methods, such as electron beam lithography. Here, we present a novel bottom-up method for the fabrication of plasmonic metasurfaces, based on silver nanoparticles (AgNPs) using a solution-based growth method. The particle growth is controlled by light, e.g. an incident laser beam. Thereby, the specific light parameters, e.g. polarization state of the light, enable in-situ engineering of the resulting metasurface. Features of engineered disorder, in particular disordered hyperuniformity, can be observed in the reciprocal space and influenced in a facile way on large areas. In addition, the particle growth can be mediated by surface plasmon polaritons, which demonstrates the extensive versatility of the presented fabrication method. As an application scenario, we show that the fabricated metasurfaces are directly applicable as self-optimized optical sensors. When compared to the growth conditions, their optical response is inherently sensitive to deviations from the electromagnetic environment. Since the presented approach allows for the use of common platforms (photonic and plasmonic) for the fabrication and the probing, the sensors remain well aligned with respect to the light source after fabrication. This way, we demonstrate high-performance nanoplasmonic sensing (FoM_max^*= 968) without the need for post-process alignments – promising for an implementation in integrated optical systems.