Effects of surface plasmon polariton-mediated interactions on second harmonic generation from assemblies of pyramidal metallic nano-cavities

Abstract

We use polarization-resolved two-photon microscopy to investigate second harmonic generation (SHG) from individual assemblies of site-controlled nano-pyramidal recess templates covered with silver films. We demonstrate the effect of the surface plasmon polaritons (SPPs) at fundamental and second-harmonic frequencies on the effective second order susceptibility tensor as a function of pyramid arrangement and inter-pyramid distance. These results open new perspectives for the application of SHG microscopy as a sensitive probe of coherently excited SPPs, as well as for the design of new plasmonic nanostructure assemblies with tailored nonlinear optical properties.

Octupolar Plasmonic Meta-Molecules for Nonlinear Chiral Watermarking at Subwavelength Scale

“…Graphic Over the past two decades, research devoted to the second-harmonic generation (SHG) from plasmonic nanostructures evolved from the investigation of hyper-Rayleigh scattering in colloidal suspensions of metal nanoparticles [1-3] towards the measurements of SHG from individual plasmonic nano-objects [4][5][6]. Far-field SHG radiation pattern has been demonstrated as a highly sensitive probe of the nanoscale optical field distribution [7], allowing for the investigation of multipolar plasmon modes [8][9][10], the analysis of surface plasmon polariton (SPP)-mediated interactions [11,12], refractive index sensing [13] and precise characterization of the nanostructure geometry [14][15][16]. In parallel, advanced theoretical tools for SHG modelling were developed, based on numerical methods such as finite elements to solve Maxwell equations and yield the scattered SHG radiation [17][18][19].…”

Non‐centrosymmetric plasmonic crystals for second‐harmonic generation with controlled anisotropy and enhancement

“…, where two polarization components of the emitted SHG are plotted separately: x‐polarized SHG in red, y‐polarized SHG in blue, while the total SHG signal is plotted in black. Although the changes in the effective nonlinear susceptibility caused by the local field factor at ω cannot be strictly accounted for by the electric dipole χ (2) tensor elements , which results in a symmetry‐forbidden signal, the character of these changes is very similar to a transition from an initially octupolar χ (2) symmetry of the individual pyramids, associated with the pure irreducible vector‐less term χ (2) J=3 , to a multipolar χ (2) symmetry, where an additional vectorial component χ (2) J=1 contributes to the overall effective nonlinear susceptibility . Here the terminology of dipolar and octupolar components relate to the χ (2) tensor symmetry which behave under point‐wise rotations in a way rigorously identical to that of the well‐known angular momentum irreducible components with the same quantum labels J = 1 and J = 3.…”

“…Aside from photonic crystals and quantum‐confined semiconductor nanostructures , plasmonic metamaterials may be considered as one of the most promising avenues for tailoring NLO properties . Second‐harmonic generation (SHG), the simplest NLO phenomenon, has been extensively studied in large variety of plasmonic nanostructures of precisely designed geometry . In nanostructures lacking an inversion center, the geometry‐induced imbalance of the Coulomb restoring force has been found to improve the efficiency of the SHG, particularly in the case of an electric dipole‐allowed nonlinear susceptibility .…”

“…Second‐harmonic generation (SHG), the simplest NLO phenomenon, has been extensively studied in large variety of plasmonic nanostructures of precisely designed geometry . In nanostructures lacking an inversion center, the geometry‐induced imbalance of the Coulomb restoring force has been found to improve the efficiency of the SHG, particularly in the case of an electric dipole‐allowed nonlinear susceptibility . Although the higher order multipolar modes in such nanostructures may have a non‐negligible contribution to the emitted SHG, it has been shown that the contribution of symmetry‐allowed electric dipole χ (2) tensor components can be tailored by means of interactions mediated by surface plasmon polaritons (SPPs) , in direct analogy to molecular NLO engineering strategies explored during the past few decades .…”

“…In nanostructures lacking an inversion center, the geometry‐induced imbalance of the Coulomb restoring force has been found to improve the efficiency of the SHG, particularly in the case of an electric dipole‐allowed nonlinear susceptibility . Although the higher order multipolar modes in such nanostructures may have a non‐negligible contribution to the emitted SHG, it has been shown that the contribution of symmetry‐allowed electric dipole χ (2) tensor components can be tailored by means of interactions mediated by surface plasmon polaritons (SPPs) , in direct analogy to molecular NLO engineering strategies explored during the past few decades . Such χ (2) engineering has recently generated great interest in view of their potential applications in plasmon‐based bio‐sensing , terahertz‐wave generation by optical rectification , as well as nanoscale sources of background‐free SPPs at 2ω for fundamental studies of plasmon‐mediated interactions, or – in the longer term – nanoscale sources of entangled plasmon pairs , based on spontaneous parametric down‐conversion, which can serve for future quantum plasmonic circuitry.…”