Multipole Interference in the Second-Harmonic Optical Radiation from Gold Nanoparticles

Abstract

We provide experimental evidence of higher multipole (magnetic dipole and electric quadrupole) radiation in second-harmonic (SH) generation from arrays of metal nanoparticles. Fundamental differences in the radiative properties of electric dipoles and higher multipoles yield opposite interference effects observed in the SH intensities measured in the reflected and transmitted directions. These interference effects clearly depend on the polarization of the fundamental field, directly indicating the importance of multipole effects in the nonlinear response. We estimate that higher multipoles contribute up to 20% of the total emitted SH field amplitude for certain polarization configurations.

Second-harmonic generation from complementary split-ring resonators

“…These findings are discussed in terms of Babinet's principle and in terms of a recently developed microscopic classical theory that leads to good agreement regarding the relative and the absolute nonlinear signal strengths. The hydrodynamic convective contribution is found to be the dominant source of secondharmonic generation-in contrast to a previous assignment [Science 313, 502 (2006) Photonic metamaterials are an emerging class of tailored composite effective materials that can provide interesting optical properties such as, e.g., magnetism at elevated frequencies [1][2][3] or an enhanced nonlinear optical response [1,[4][5][6][7][8][9][10]. Indeed, in a series of recent experiments [6-8], we have observed second-harmonic generation (SHG) from planar arrays of gold split-ring resonators (SRRs) exhibiting a pronounced magnetic-dipole response.…”

“…Photonic metamaterials are an emerging class of tailored composite effective materials that can provide interesting optical properties such as, e.g., magnetism at elevated frequencies [1][2][3] or an enhanced nonlinear optical response [1,[4][5][6][7][8][9][10]. Indeed, in a series of recent experiments [6][7][8], we have observed second-harmonic generation (SHG) from planar arrays of gold split-ring resonators (SRRs) exhibiting a pronounced magnetic-dipole response.…”

The role of chiral local field enhancements below the resolution limit of Second Harmonic Generation microscopy

“…These enhancements find a practical application in tip-enhanced SHG scanning near-field microscopy [24], in further enhancing the SHG in nonlinear optical materials, such as GaAs [25] and in the possibility to detect single nanoparticles [26][27]. From the fundamental point of view, the local field enhanced SHG allows the study of contributions to the signal from physical mechanisms that are typically very small, namely multipolar contributions to the SHG [28][29][30] or electric dipole contributions from the bulk [31]. Additionally, the plasmonic mechanisms themselves, such as coupling between the charge oscillations, can be studied in the SHG enhanced signal [32][33][34][35].…”

Linearly polarized second harmonic generation microscopy reveals chirality

“…It is well known for its surface and interface sensitivity down to the atomic submonolayer scale, which favors greatly the technique for probing nanostructures where the surface to volume ratio is among the largest. Consequently, there is a growing interest in applying SHG to nanoparticles and nanopatterned materials [17][18][19][20][21][22][23][24][25][26].…”