Papers by Keyword: Nonlinear Refraction

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Authors: Qing Chang, Xi Wen Liu
Abstract: Based on Z-scan technique, the nonlinear absorption and refraction characteristics of multi-walled carbon nanotubes (MWNT) in chloroform , deionized water and isopropyl alcohol have been studied under the picosecond (ps) laser pulses, respectively. The experimental results show that the nonlinear absorption characteristics of the MWNT in chloroform, deionized water and isopropyl alcohol are all saturable absorption, and their nonlinear absorption coefficients are 1.83×10-11 m/W, 1.97×10-11 m/W, 2.31×10-11 m/W, respectively. The nonlinear refraction characteristics of the three solutions are all self-focusing, and the nonlinear refractive coefficients are 4.37×10-12 esu, 1.68×10-12 esu, 8.34×10-13 esu, respectively. The third-order nonlinear susceptibilities of the three solutions are 6.32×10-13 esu, 5.62×10-13 esu, 7.11×10-12 esu, respectively. The experimental results indicate that the nonlinear optical property of the MWNT isopropyl alcohol solution is the strongest, and the MWNT deionized water solutions is the weakest. The solvents have a big effects on the nonlinear optical properties of MWNT solutions.
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Authors: Jae Tae Seo, S.M. Ma, K. Lee, H. Brown, A. Jackson, T. Skyles, N.M. Cubbage, B. Tabibi, K.P. Yoo, Suk Young Kim, S.S. Jung, M. Namkung
Abstract: Highly porous silica nanoaerogels with low apparent density of ~0.1 g/cm3 and ~0.07 g/cm3 were synthesized through two-step sol-gel processing and low temperature supercritical fluid drying. The nonlinear refraction (γ) of silica nanoaerogels was estimated to be ~ -3.4 x 10-16 m2/W for ~0.1 g/cm3 and ~0.07 g/cm3 apparent densities with a signal-beam femtosecond z-scan spectroscopy. The third-order nonlinear refraction coefficient of nanostructure silica nanoaerogels was almost four orders larger than that of bulk silica materials. The large nonlinearrefraction with high nonlinear figure of merit (γ/βλ, β~2×10-10 m/W for 0.07 g/cm3 apparent density, β~6×10-10 m/W for 0.1 g/cm3 apparent density, λ~0.775 µm) is an ideal optical property for nonlinear applications of homeland security, battlefield enhancement, and industrial uses.
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Authors: Qing Chang
Abstract: The nonlinear refraction and absorption properties of a PEI (phthalocyanine indium) tetrasulphonated chlorinated phthalocyanine electrostatic self-assembled film were studied using a simple and high sensitivity technique. We adopted picosecond laser pulses as source light and modified top-hat Zscan technique with a disk and a small aperture to explore the nonlinear refraction of the film. Experimental results show that the measuring sensitivity is increased by two orders of magnitude. Through theoretical fitting, we obtain the nonlinear refraction index and nonlinear absorption coefficients of the film are 2.1×10-14 m2/W and 2.4×10-7 m/W, respectively.
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Authors: Heng Yu Tan, Qing Chang, Xi Wen Liu
Abstract: The nonlinear absorption and nonlinear refraction properties of water soluble ZnS semiconductor quantum dots are studied by using Z-scan technique with the action of 400 nm and 532 nm femtosecond laser pulses. The experimental results show that the three order nonlinear effect of ZnS semiconductor quantum dot is stronger in 400 nm laser pulse, and it is weaker in 532 nm laser pulse. The three order nonlinear polarization coefficient of ZnS semiconductor quantum dot is 4.58×10-13 esu with the action of 400 nm laser pulse, it is 9.22×10-14 esu with the action of 532nm laser pulse. The ZnS semiconductor quantum dot has a relatively good three order optical nonlinear effect with the action of 400nm wavelength laser pulse.
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