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Proceedings Paper

Nonlinear scattering in gold nanospheres
Author(s): Po-Ting Shen; Cheng-Wei Lin; Hsiang-Lin Liu; Shi-Wei Chu
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Paper Abstract

Nonlinearity enhanced by noble metallic nanoparticles provide novel light manipulation capabilities and innovative applications. Recently, we discovered a new nonlinear phenomenon on the scattering of metallic nanoparticles by continuous-wave (CW) lasers at the intensity around MW/cm2 and applied to super-resolution microscopy that allowed spatial resolution of plasmonic nanostructures down to λ/8. However, its mechanism is still unknown. In this work, we elaborate the mechanism behind the nonlinear scattering of gold nanospheres. There are four possible candidates: intraband transition, interband transition, hot electron, and hot lattice. Each of them has a corresponding nonlinear refractive index (n2), which is related to temporal dependence of its light-matter interaction. We first measure the intensity dependence of nonlinear scattering to extract the effective n2 value. We find out it has the closest n2 value to hot lattice, which causes either the shift or weakening of the surface plasmon resonance (SPR). To further verify the mechanism, the nanospheres are heated up with both a hot plate and a CW laser, and the variation of single-particle SPR scattering spectra are measured. In both cases, more than 50% reduction of scattering is observed, when temperature rises a few tens of degrees or when illumination intensity reaches the order of 1MW/cm2. Thus, we conclude the spectra variation by the two different heating source, as well as the nonlinear scattering are all due to hot lattice, and subsequent permittivity change with temperature. The innovative concept of hot lattice plasmonics not only opens up a new dimension for nonlinear plasmonics, but also predicts the potential of similar nonlinearity in other materials as long as their permittivity changes with temperature.

Paper Details

Date Published: 4 March 2016
PDF: 8 pages
Proc. SPIE 9742, Physics and Simulation of Optoelectronic Devices XXIV, 97421G (4 March 2016); doi: 10.1117/12.2209297
Show Author Affiliations
Po-Ting Shen, National Taiwan Univ. (Taiwan)
Cheng-Wei Lin, National Taiwan Normal Univ. (Taiwan)
Hsiang-Lin Liu, National Taiwan Normal Univ. (Taiwan)
Shi-Wei Chu, National Taiwan Univ. (Taiwan)


Published in SPIE Proceedings Vol. 9742:
Physics and Simulation of Optoelectronic Devices XXIV
Bernd Witzigmann; Marek Osiński; Yasuhiko Arakawa, Editor(s)

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