Nonlinear absorption in Au films: Role of thermal effects
Nonlinear absorption in Au films: Role of thermal effects
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DOI：
10.1103/physrevb.75.155426
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发表时间：
2007-04-01
影响因子：
3.7
通讯作者：
van Driel, H. M.
中科院分区：
文献类型：
--
作者：
Rotenberg, Nir;Bristow, A. D.;van Driel, H. M.
测量了20 nm厚的Au薄膜在630 nm处的有效非线性光学吸收系数β（eff）随脉冲宽度的变化。z扫描测量表明，当脉冲宽度从0.1 ps变化到5.8 ps时，β（eff）从6.8 × 10（-7）cm W-1增加到6.7 × 10（-5）cm W-1。为了帮助解释这种类似于100倍的增加，使用775 nm泵浦和630 nm探测脉冲进行差分透射率和反射率测量。所有的实验都是用电子和晶格的双温模型来模拟的。β（eff）的脉冲宽度依赖性与d带到导带跃迁的热拖尾一致，其中β（eff）由线性（Im χ（1））吸收系数的变化引起。
The effective nonlinear optical absorption coefficient beta(eff) is measured for 20-nm-thick Au films at 630 nm as a function of pulse width. The z-scan measurements show that beta(eff) increases from 6.8x10(-7) to 6.7x10(-5) cm W-1 as the pulse width is varied from 0.1 to 5.8 ps. To help interpret this similar to 100x increase, differential transmission and reflectivity measurements are performed using 775 nm pump and 630 nm probe pulses. All experiments are simulated with a two-temperature model for electrons and lattice. The pulse width dependence of beta(eff) is consistent with thermal smearing of d-band to conduction-band transitions, with beta(eff) arising from changes in the linear (Im chi((1))) absorption coefficient.