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| The optical nonlinearities of the Au nanoparticle array were determined by performing the Z-scan method with a femtosecond laser (800 nm, 50 fs). As the exciting energy increased, the nonlinear absorption of the Au nanoparticle array changed from reverse-saturable absorption to saturable absorption, while the nonlinear refraction changed over from self-focusing to self-defocusing, which implies that competition between ground state bleaching and two-photon absorption. The one- and two-photon figures of merit, W=5.1 and T=0.5, respectively, were obtained, which satisfies the demand, W>1 and T<1, for all-optical switching. |
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| Keywords:Nanosphere Lithography;Au Nanoparticles;Third-order Nonlinearity |
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