Anisotropic nonlinear optical absorption of gold nanorods in a silica matrix |
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Authors: | Jean-Michel Lamarre Franck Billard Michel Lequime Ludvik Martinu |
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Affiliation: | a Department of Engineering Physics, École Polytechnique de Montréal, C.P. 6079, succ. Centre-Ville, Montréal, Québec, Canada H3C 3A7 b Institut Fresnel, UMR CNRS 6133, Université Paul-Cézanne Aix-Marseille III, 13397 Cedex 20, Marseille, France c Physics Department, Université de Montréal, C.P. 6128, succ. Centre-Ville, Montréal, Québec, Canada H3C 3J7 |
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Abstract: | Nanocomposite films consisting of gold nanospheres or gold nanorods embedded in a silica matrix have been prepared using a hybrid deposition technique consisting of plasma-enhanced chemical vapor deposition of SiO2 and co-sputtering of gold, followed by annealing at 900 °C. Subsequent irradiation with 30 MeV heavy ions (Cu5+) was used to form gold nanorods. Linear and nonlinear optical properties of this material are closely related with the surface plasmon resonance in the visible. The nonlinear absorption coefficient (α2@532 nm) for the films containing gold nanospheres was measured by Z-scan and P-scan techniques, and it was found to be isotropic and equal to −4.8 × 10−2 cm/W. On the contrary, gold nanorods films exhibited two distinct surface plasmon resonance absorption bands giving rise to a strong anisotropic behavior, namely a polarization-dependent linear absorption and saturable absorption. Z-scan and P-scan measurements using various light polarization directions yielded nonlinear absorption coefficient (α2@532 nm) values varying from −0.9 × 10−2 cm/W up to −3.0 × 10−2 cm/W. Linearity of the P-scan method in the context of nanocomposite saturable absorption is also discussed. |
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Keywords: | 42.65.&minus k 72.80.Tm |
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