Dynamic Characterization and Impulse Response Modeling of Amplitude and Phase Response of Silicon Nanowires

Amplitude and phase dynamics of silicon nanowires were measured using time-resolved spectroscopy. Time shifts of the maximum phase change and minimum amplitude as a function of pump power due to saturation of the free-carrier density were observed. A phenomenological impulse response model used to fit the experimental data indicated that the free-carrier lifetime was between $7.5 \leq \tau_{\rm fc} \leq 16.2\ \hbox{ns}$, and the two-photon absorption coefficient and the Kerr coefficient were $3 \times 10^{-12}\ \hbox{m.W}^{-1}$ and $4 \times 10^{-18}\ \hbox{m}^{2}.\hbox{W}^{-1}$, respectively, for silicon nanowires with lengths varying from 3.6 to 14.9 mm.