| Summary: | 碩士 === 國立中正大學 === 物理學系暨研究所 === 100 === We report on nonlinear absorptive and refractive properties of simple transparent liquids methanol, carbon tetrachloride and their mixtures using the Z-scan technique with a Ti:sapphire laser. This laser delivers pulses with a central wavelength of 817nm, a repetition rate of 82MHz, a pulse width (FWHM) of 30fs and a maximal average power of 300mW.
Thermal lensing effect was observed for all liquids and was found to increase with the pulse train width and gradually turn steady on the time scale of the characteristic time of thermal diffusivity. In liquid mixtures, the interactions between the component liquids would enhance or weaken the thermal lensing effect, which is predominantly contributed by temperature gradient induced concentration gradient, namely the Soret effect.
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