Projecting Plasmonic Meta-Atom Resonances into Far Field Scattering Using Lattice Modes

Au H-shaped nanoantennas provide highly tunable resonances via controlled mixtures of multipolar plasmonic modes, making them unique candidates for plasmonic metasurfaces with diverse applications. In this work, we study the influence of optical lattice modes on the far-field scattering of arrays of such nanoantennas. The scattering process was detected along the plane of the arrays (in-plane scattering), demonstrating directional enhancement of far fields via coherent coupling of these modes with the plasmon resonances supported by the H-shaped nanoantennas. The results reveal the impact of in-phase excitation of such resonances, formed via hybridization of multipolar plasmon resonances associated with the parallel and connecting arms of the H-shaped nanoantennas, on the far-field scattering. Our results indicate that for a longer wavelength range, wherein the impact of lattice becomes small, the in-plane scattering exhibits intensity plateaus with minimal wavelength dependency in the wide range of 1–1.5 μm. This study highlights the unique capability of in-plane far-field scattering to provide insights into meta-atoms with engineered near-field profiles, which transmission-based measurement techniques cannot achieve.