Third-order nonlinear optical response of Au:SiO
2
thin films: Influence of gold nanoparticle concentration and morphologic parameters |
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Authors: | N Pinçon B Palpant D Prot E Charron S Debrus |
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Institution: | (1) Laboratoire d'Optique des Solides, CNRS - Université Pierre et Marie Curie, Case 80, 4 place Jussieu, 75252 Paris Cedex 05, France, FR |
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Abstract: | We report a study on the third-order nonlinear optical properties of nanocomposite thin films composed of gold particles embedded
in a silica host matrix. Samples of various metal volume fractions, ranging from 8 to 35%, are synthesized by the sputtering
technique. Some of them are annealed. Nonlinear optical measurements, which are performed by using the z-scan technique, reveal both a very large nonlinear absorption and a weak nonlinear refraction close to the surface plasmon
resonance frequency of the particles. We especially study the effect of the metal concentration and the influence of thermal
treatment on the real and imaginary components of the third-order nonlinear susceptibility. Our results reveal that, as the
metal concentration reaches a few percent, the mutual electromagnetic interactions between particles greatly enlarge the nonlinear
optical response of the material and can not be neglected in the theoretical analysis. Moreover, the thermal treatment leads,
for a given concentration, to a significant increase of the nonlinear response, which is ascribed to a modification of the
material morphology. We finally point out that the material nonlinear properties are very sensitive to the incident wavelength
through the local field enhancement phenomenon.
Received 12 December 2001 |
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Keywords: | PACS 78 67 Bf Nanocrystals and nanoparticles – 42 65 An Optical susceptibility hyperpolarizability – 61 46 +w Nanoscale materials: clusters nanoparticles nanotubes and nanocrystals |
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