Linear and third-order nonlinear optical properties of self-assembled plasmonic gold metasurfaces

The emergence of metamaterials (MMs) has led to groundbreaking photo-physical phenomena, which arise from their novel structure-dependent properties. Consisting of “meta-atom” building blocks, MMs can be organized into subwavelength metal/dielectric structures using bottom-up or top-down nanofabrication techniques. Optical metal metasurfaces are a class of MMs with macroscopic lateral dimensions but composed of one to few subwavelength layers of precisely oriented metal-based elements over a large surface area. In this review, we focus on gold metasurfaces, highlighting their fabrication methods, morphological characterization, as well as linear and nonlinear optical properties. We then review our recent work on fabricating and characterizing self-assembled gold metasurface. An interesting characteristics of the gold metasurfaces is their wide range of linear refractive indices, varying from n0 ~ 0.5 in the visible to n0 ~ 4 in the short wavelength infrared spectral region. Third-order nonlinearities are characterized by the Z-scan technique at wavelengths on- and off-plasmonic resonance of the gold metasurface. Experimental results on the relationship between the third-order nonlinearity of the self-assembled gold metasurface as a function of the linear response are presented for the first time. We conclude by discussing the potential applications and future outlook of self-assembled plasmonic metasurfaces.