Enhanced second harmonic generation from a plasmonic Fano structure subjected to an azimuthally polarized light beam

Abstract

We show that an azimuthally polarized beam (APB) excitation of a plasmonic Fano structure made by coupling a split-ring resonator (SRR) to a nanoarc can enhance second harmonic generation (SHG). Strikingly, an almost 30 times enhancement in SHG peak intensity can be achieved when the excitation is switched from a linearly polarized beam (LPB) to an APB. We attribute this significant enhancement of SHG to the corresponding increase in the local field intensity at the fundamental frequency of SHG, resulting from the improved conversion efficiency between the APB excitation and the plasmonic modes of the Fano structure. We also show that unlike LPB, APB excitation creates a symmetric SHG radiation pattern. This effect can be understood by considering an interference model in which the APB can change the total SHG far-field radiation by modifying the amplitudes and phases of two waves originating from the individual SRR and nanoarc of the Fano structure.

Second Harmonic Generation Enhancement From Plasmonic Toroidal Resonance in Core-Shell Nanodisk

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Enhanced Nonlinear Light Generation in Oligomers of Silicon Nanoparticles under Vector Beam Illumination

“…Under normal incidence, selective excitation of optical modes in nanoparticles and nanoparticle oligomers − can be achieved by cylindrical vector beams (CVBs) with azimuthal or radial polarization. Separate control over the induced electric and magnetic dipolar modes can result in, for example, directional scattering − and dark mode formation. − The modes excited by CVBs also reveal themselves in efficient harmonics generation that has been experimentally demonstrated for individual Mie-resonant nanoparticles, − plasmonic oligomers consisting of metal nanorods with different spatial symmetries, and plasmonic Fano structures . However, the excitation of collective optical modes in isolated all-dielectric oligomers by structured light for enhancement of the nonlinear optical effects has not been experimentally and numerically studied so far.…”

Enhanced Second-Harmonic Generation from Fanolike Resonance in an Asymmetric Homodimer of Gold Elliptical Nanodisks

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