Modeling of second-order nonlinear metasurfaces

Abstract

We present a frequency-domain modeling technique for second-order nonlinear metasurfaces. The technique is derived from the generalized sheet transition conditions (GSTCs), which have been so far mostly used for modeling linear metasurfaces. In this work, we extend the GSTCs to include effective nonlinear polarizations. This allows retrieving the effective nonlinear susceptibilities of a given metasurface and predict its nonlinear scattering responses under arbitrary illumination conditions. We apply this modeling technique to the case of metasurfaces made of a periodic arrangement of T-shaped gold nanoparticles. For verification, several metasurfaces are fabricated and a fair agreement is found when comparing simulated data and experimental results. The proposed model may thus serve as a design platform to implement complex nonlinear metasurface based applications.

Nonlinear Optical Response of a Plasmonic Nanoantenna to Circularly Polarized Light: Rotation of Multipolar Charge Density and Near-Field Spin Angular Momentum Inversion

“…To this end, the hydrodynamic description adopted to address the nonlinear response of conduction electrons, and first applied to characterize the second-harmonic generation from metals and metal surfaces, − has been further developed recently. Efficient numerical approaches to address the nonlinearity of plasmonic nanoparticles have been thus proposed. ,− In this context, the situation where the fundamental wave is linearly polarized has been studied both theoretically and experimentally, providing a deep understanding about the main processes that control the second-order − ,− and the third-order ,− response of plasmonic nanoantennas and subnanometric plasmonic gaps prone to sustain optically assisted tunneling. − However, with the exception of chiral systems ,− (where one is naturally interested in the nonlinear activity triggered by SAM-carrying incident fields), the case of a circularly polarized fundamental wave interacting with typical plasmonic nanoantennas has received less attention for nonlinear plasmonic applications.…”

Multipolar expansions for scattering and optical force calculations beyond the long wavelength approximation

“…The strength of this approach lies in the fact that, by considering only the first few leading terms of the expansion, a sufficient convergence of the multipolar solution can be achieved without the need to undertake the full calculation, thus greatly simplifying the problem. For this reason, multipolar expansions have been exploited for a broad variety of applications including the study and design of radiation patterns for electromagnetic sources 11,12 , the determination of molecular and atomic polarizabilities [13][14][15] and the design and characterization of metasurfaces [16][17][18][19][20][21] . Other examples include the scattering of electromagnetic radiation by an object [22][23][24][25][26] and the generation of optical forces on a scatterer 22,[27][28][29][30][31] .…”

Demonstration of a Plasmonic Nonlinear Pseudodiode

“…To further elucidate the significance of bianisotropy in such an asymmetric response, we extracted the effective susceptibilities from the simulated electromagnetic fields following the previously documented procedure of metasurface homogenization analysis. − Briefly, the expressions for nonlinear susceptibilities are derived from the generalized sheet transition conditions and are calculated using the simulated reflected and transmitted fields upon different excitation conditions at ω and 2ω frequencies.…”