饱和吸收
材料科学
皮秒
吸收(声学)
激光器
纳米点
光电子学
光学
波长
光纤激光器
物理
复合材料
作者
Ullas Gurudas,E Bruce Brooks,Daniel M. Bubb,S. Heiroth,Thomas Lippert,Alexander Wokaun
摘要
Saturable absorption (SA) and reverse saturable absorption (RSA) at 532 nm were observed in Ag nanodots prepared by pulsed laser deposition. The real [Re χ(3)] and imaginary [Im χ(3)] parts of the third order nonlinearity of these films were measured using the Z-scan technique. At low input irradiances, the decrease in absorption near the focal point results from a negative Im χ(3) and yields SA. At higher input irradiance, RSA becomes dominant. The transition from SA to RSA suggests that there is a threshold irradiance at which additional nonlinear process(es) is (are) involved and become dominant. The recovery time of these nonlinear processes was measured by a degenerate pump-probe experiment. The effects are explained in terms of the electron dynamics in the excited states.
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