中文摘要：

采用射频磁控溅射技术制备了Ge掺二氧化硅（Ge—SiO2）和Ge，Al共掺二氧化硅（Ge／Al—SiO2）两种复合薄膜，并进行了热退火处理形成了纳米Ge镶嵌结构。通过紫外-可见吸收谱测量，确定了两种薄膜中纳米Ge的光学带隙，并采用皮秒激光二扫描技术研究了薄膜的非线性光学性质。测试结果显示，在1064nm激发下得到的Ge—SiO2和Ge／Al-SiO2薄膜的非线性吸收系数分别为-1．23×10-7m／V和4．35×10-8m／W，前者为饱和吸收，而后者为双光子吸收。把两种薄膜作为可饱和吸收体均可实现1．06μm激光的被动调Q和被动锁模运转。与Ge—SiO2薄膜比较，采用Oe／Al-SiO2薄膜可以获得较窄的调Q脉冲和锁模脉冲。最后，理论分析和实验比较了两种薄膜实现被动调Q和锁模的机理。

英文摘要：

The Ge-SiO2 and Ge/Al-SiO2 compound films were prepared by Radio-Frequency （RF） mag- netron sputtering technique, and then Ge nanocrystals were obtained in the films by a thermal annea- ling treatment. The optical bandgaps of the Ge nanocrystals in the two films were calculated by meas- ured UV-visible absorption spectral data, and the nonlinear optical properties of the two compound films were investigated by using picosecond laser Z-scan technique. Experiments show that the nonlin- ear absorption coefficients of Ge-SiO2 and Ge/Al-SiO2 films at 1 064 nm lasing are - 1.23 × 10 -7 m/V and 4.35×10-8 m/W, respectively. The former corresponds to the saturable absorption, while the latter corresponds to the two-photon absorption. Furthermore, both the Ge-SiO2 and Ge/Al-SiO2 films can be as the saturable absorbers to implement the passive Q-switching and mode-locking operation for a 1.06 μm laser. Obtained experimental results demonstrate that Ge/Al-SiO2 film could achieve narro- wer Q-switched pulse and mode-locked pulse than that of the Ge-SiO2 film. Finally, it discusses the mechanisms of passive Q-switching and passive mode-locking with the two films.