Ultrashort and short pulse nonlinear optical investigations in thiolated nine-atom silver quantum clusters embedded in one-dimensional TiO2 nanotube matrix

Abstract Nanostructured materials employed as passive nonlinear absorptive limiters offer protection to the human eyes and optical sensors from damage by pulsed laser radiation. However, such materials are prone to laser induced damage, which can be avoided or minimized by employing a robust shell layer. Here, we report the optical limiting properties of nine-atom silver quantum clusters grafted in TiO2 nanotube matrix (Ag9QCs-TNT). Nonlinear absorption revealed from open-aperture Z-scan measurements on Ag9QCs-TNT using both 5 ns (532 nm) and 100 fs (800 nm) laser pulses is larger than those observed from its pristine counterparts (Ag9QCs and TNT). The optical limiting threshold value obtained for Ag9QCs-TNT under fs excitation is smaller by a factor of five compared to that under ns excitation, indicating its ability to passively limit high intensity laser radiation for potential device applications.