金属超微粒子-半导体薄膜的光学瞬态响应

利用飞秒脉冲激光和泵浦 探测技术测量了金属超微粒子 半导体复合薄膜Ａｇ-ＢａＯ的瞬态光学透过率随延迟时间的变化曲线，观察到了薄膜对光的吸收漂白现象，并在不到２ｐｓ时间内恢复．该现象是薄膜中金属超微粒子内费密能级附近电子被飞秒激光脉冲激发，产生非平衡电子而经历瞬态弛豫造成的．弛豫主要包括非平衡电子越过超微粒子和周围介质的界面位垒进入周围介质，以及非平衡电子同晶格和界面的散射两种过程．超微粒子粒径的差别会引起非平衡电子弛豫时间的差别关键词：

OPTICAL TRANSIENT RESPONSE OF METALLIC ULTRAFINE PARTICLES EMBEDDED IN SEMICONDUCTOR THIN FILM

The femtosecond laser pulses and pump-probe method have been used to measure the transient change of transmissivity of metallic ultrafine particles(UFPs) embedded in semiconductor thin film (Ag-BaO). The phenomena that the optical absorption of the films decreases and then restores within 2ps have been observed. The phenomena are due to the fact that electrons near the Fermi energy level in Ag UFPs are excited by femtosecond laser pulses and then the generated nonequilibrium electrons undergo a transient relaxation. The relaxation includes includes two parts: first, nonequilibrium electrons from Ag UFPs enter the matrix;then,nonequilibrium electrons are scattered by the lattice and inter-face between the Ag UFPs and the matrix. The different diameters of Ag UFPs affter the relaxation time of nonequilibrium electrons.