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[摘要]：We report the giant optical nonlinear absorption and refraction of Sb2Te3 phase change materials at low laser irradiation intensities. The nonlinear absorption and refraction coefficients reach up to -6.63 x 10(-2) m/W and 2.606 x 10(-9) m(2)/W, respectively. The first principles calculation indicates that the giant nonlinear absorption stems from the band filling effect of the photon induced free carriers under laser irradiation. The band-gap shrinking results in a positive thermo-optic coefficient, thus the giant nonlinear refraction. The numerical results are generally correlated with the experimental findings from z-scan and temperature-variable ellipsometric measurements. (C) 2010 American Institute of Physics. [doi:10.1063/1.3530428] |
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