Symmetry-breaking-induced off-resonance second-harmonic generation enhancement in asymmetric plasmonic nanoparticle dimers Wang, Y., Z. Peng, Y. De Wilde, and D. Lei Nanophotonics (2024)
Résumé: The linear and nonlinear optical properties of metallic nanoparticles have attracted considerable experimental and theoretical research interest. To date, most researchers have focused primarily on exploiting their plasmon excitation enhanced near-field and far-field responses and related applications in sensing, imaging, energy harvesting, conversion, and storage. Among numerous plasmonic structures, nanoparticle dimers, being a structurally simple and easy-to-prepare system, hold significant importance in the field of nanoplasmonics. In highly symmetric plasmonic nanostructures, although the odd-order optical nonlinearity of the near-surface region will be improved because of the enhanced near-fields, even-order nonlinear processes such as second-harmonic generation (SHG) will still be quenched and thus optically forbidden. Under this premise, it is imperative to introduce structural symmetry breaking to realize plasmon-enhanced even-order optical nonlinearity. Here, we fabricate a series of nanoparticle dimers each composed of two gold nanospheres with different diameters and subsequently investigate their structural asymmetry dependent linear and nonlinear optical properties. We find that the SHG intensities of gold nanosphere dimers are significantly enhanced by structural asymmetry under off-resonance excitation while the plasmonic near-field enhancement mainly affects SHG under on-resonance excitation. Our results reveal that symmetry breaking will play an indispensable role when designing novel coupled plasmonic nanostructures with enhanced nonlinear optical properties.
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Spatial coherence in strongly scattering media Pierrat, R., R. Elaloufi, J.-J. Greffet, and R. Carminati Journal of the Optical Society of America A 22, no. 11, 2329 (2005)
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Photon diffusion coefficient in scattering and absorbing media Pierrat, R., J.-J. Greffet, and R. Carminati Journal of the Optical Society of America A 23, no. 5, 1106 (2006)
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Light propagation in multilayered scattering media beyond the diffusive regime Elaloufi, R., S. Arridge, R. Pierrat, and R. Carminati Applied Optics 46, no. 13, 2528 (2007)
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Threshold of random lasers in the incoherent transport regime Pierrat, R., and R. Carminati Physical Review A 76, no. 2 (2007)
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The influence of the scattering anisotropy parameter on diffuse reflection of light Pierrat, R., N. B. Braham, L. F. Rojas-Ochoa, R. Carminati, and F. Scheffold Optics Communications 281, no. 1, 18-22 (2008)
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Multiple scattering theory in one dimensional space and time dependent disorder: average field [Invited] Selvestrel, A., J. Rocha, R. Carminati, and R. Pierrat Optical Materials Express 14, no. 3, 801-815 (2024)
Résumé: We theoretically study the propagation of light in one-dimensional space- and time-dependent disorder. The disorder is described by a fluctuating permittivity ε(x, t) exhibiting short-range correlations in space and time, without cross correlation between them. Depending on the illumination conditions, we show that the intensity of the average field decays exponentially in space or in time, with characteristic length or time defining the scattering mean-free path ℓs and the scattering mean-free time τs. In the weak scattering regime, we provide explicit expressions for ℓs and τs, that are checked against rigorous numerical simulations.
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Light in correlated disordered media Vynck, K., R. Pierrat, R. Carminati, L. S. Froufe-Pérez, F. Scheffold, R. Sapienza, S. Vignolini, and J. J. Sáenz Reviews of Modern Physics 95, no. 4 (2023)
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