Ultrafast optical phase modulation with metallic nanoparticles in ion-implanted bilayer silica |
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Authors: | Torres-Torres C Tamayo-Rivera L Rangel-Rojo R Torres-Martínez R Silva-Pereyra H G Reyes-Esqueda J A Rodríguez-Fernández L Crespo-Sosa A Cheang-Wong J C Oliver A |
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Affiliation: | Sección de Estudios de Posgrado e Investigación, ESIME-Z, Instituto Politécnico Nacional, México, DF, Mexico. crstorres@yahoo.com.mx |
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Abstract: | The nonlinear optical response of metallic-nanoparticle-containing composites was studied with picosecond and femtosecond pulses. Two different types of nanocomposites were prepared by an ion-implantation process, one containing Au nanoparticles (NPs) and the other Ag NPs. In order to measure the optical nonlinearities, we used a picosecond self-diffraction experiment and the femtosecond time-resolved optical Kerr gate technique. In both cases, electronic polarization and saturated absorption were identified as the physical mechanisms responsible for the picosecond third-order nonlinear response for a near-resonant 532 nm excitation. In contrast, a purely electronic nonlinearity was detected at 830 nm with non-resonant 80 fs pulses. Regarding the nonlinear optical refractive behavior, the Au nanocomposite presented a self-defocusing effect, while the Ag one presented the opposite, that is, a self-focusing response. But, when evaluating the simultaneous contributions when the samples are tested as a multilayer sample (silica-Au NPs-silica-Ag NPs-silica), we were able to obtain optical phase modulation of ultra-short laser pulses, as a result of a significant optical Kerr effect present in these nanocomposites. This allowed us to implement an ultrafast all-optical phase modulator device by using a combination of two different metallic ion-implanted silica samples. This control of the optical phase is a consequence of the separate excitation of the nonlinear refracting phenomena exhibited by the separate Au and Ag nanocomposites. |
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