Scattering of second-harmonic light from small spherical particles ordered in a crystalline lattice

Abstract

Experimental evidence of scattering of second-harmonic light from the surface of spherical particles of optical dimensions is presented. This mechanism for second-harmonic generation is observed in a suspension of monodisperse spherical colloidal particles, ordered in a centrosymmetric crystalline lattice. In this periodic structure the mechanism of phase matching is provided by the bending of the photon dispersion curve near the Bragg reflection band. A simple theoretical analysis based on the Rayleigh-Gans scattering approximation shows that constructive interference of the second-harmonic light scattered from different portions of a singlesphere surface leads to a nonvanishing field with a quadrupolar distribution intensity pattern. ͓S1050-2947͑97͒06506-2͔

Communication: Reactions and adsorption at the surface of silver nanoparticles probed by second harmonic generation

“…On the other hand, though the particle is small, its finite size still enables the phase matching condition for SHG at the particle surface to be satisfied at large scattering angles. [6][7][8][9] Indeed, SHG from molecules with large hyperpolarizability adsorbed on dielectric nanoparticle surfaces has been detected at large scattering angles. [10][11][12][13] In the case of metallic nanoparticles, the surface layer should have a large enough hyperpolarizability to allow for direct detection of surface generated SH signal even in the absence of an adsorbed layer of hyperpolarizable molecules.…”

Nonlinear optics in spheres: from second harmonic scattering to quasi‐phase matched generation in whispering gallery modes

“…At the exit of the sphere, both field and molecules would have changed orientation, making the second harmonic (SH) signal on both sides add constructively. Such a, to a certain extent, naive picture of the nonlinear interaction on a sphere surface was confirmed by the results of a model that considered SH scattering in the Rayleigh-Gans-Debye approximation (see below) from single spheres whose diameter was close to the wavelength of light [4]. Second harmonic generation (SHG) was configured in two large lobes on the scattering plane symmetrically located relative to the forward direction.…”

“…In 1995, it was proposed and experimentally demonstrated that the use of dielectric spheres with diameters close to one wavelength of the generated wave and coated with a nonlinear material could obviate the need to use noncentrosymmetric materials at a macroscopic scale [2,3]. The electric field vector at the entrance side of the sphere would interact with molecules that point at a given direction.…”

Plasmonic enhancement of second harmonic generation on metal coated nanoparticles

“…The response of small particles can be modeled by Second-Harmonic Rayleigh Scattering [43][44][45][46]. For small particles of low refractive index contrast, which do not significantly perturb the incident field, also the Rayleigh-Gans-Debye approximation can be used [47][48][49][50][51]. Larger spheres or such with a high refractive index contrast require the application of a full Mie theory, based on which several numerical models have been developed for solid particles [18,19,[52][53][54].…”