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dc.contributor.advisorMaaza, M.
dc.contributor.authorZongo, Sidiki
dc.description>Magister Scientiae - MScen_US
dc.description.abstractRecent research shows that the study of optical properties of organic material natural dyes has gained much consideration. The specific functional groups in several natural dyes remain essential for the large nonlinear absorption expressed in terms of nonlinear optical susceptibilities or other mechanism of absorption such as two photon absorption (TPA), reverse saturable absorption (RSA) or intensitydependent refractive index characteristic. In this thesis we highlight the optical limiting responses of selected natural dyes as nonlinear response in the femtosecond regime. This technique refers to the decrease of the transmittance of the material with the increased incident light intensity.Three dyes derived from beetroot, flame flower and mimosa flower dyes were investigated. The results showed a limiting behaviour around 795 mW for the beetroot and the flame dye while there is total transmission in the flame dye sample. The performance of the nonlinearity i.e. the optical limiting is related to the existence of alternating single and double bonds(i.e. C-C and C=C bonds) in the molecules that provides the material with the electron delocalization, but also it is related to the light intensity.Beside nonlinearity study, crystallographic investigation was carried out for more possible applicability of the selected dyes and this concerned only the mimosa and flame flower dye thin film samples since the beetroot thin film was very sensitive to strong irradiation (i.e. immediately destroyed when exposed to light with high intensity). For more stability,dye solutions were encapsulated in gels for further measurements.en_US
dc.publisherUniversity of the Western Capeen_US
dc.subjectNonlinear propertiesen_US
dc.subjectNatural dyesen_US
dc.subjectOptical limitingen_US
dc.subjectFemtosecond laseren_US
dc.subjectRefractive indexen_US
dc.subjectMultiphoton absorptionen_US
dc.titleNonlinear optical properties of natural dyes based on optical resonanceen_US
dc.rights.holderUniversity of the Western Capeen_US

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