纳米半导体复合薄膜的非线性光学性质及其在激光器中的应用  

Nonlinear optical properties of nanometer semiconductor compound films and their applications to lasers

作　　者：王加贤[1] 林正怀[1] 张培[1] 吴志军[1] 

机构地区：[1]华侨大学信息科学与工程学院,福建厦门361021

出　　处：《光学精密工程》2013年第1期20-25,共6页Optics and Precision Engineering

基　　金：国家自然科学基金重点项目(No.60838003);福建省自然科学基金资助项目(No.2012J01277);福建省青年科技人才创新基金资助项目(No.2001J030)

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Z-扫描技术研究了薄膜的非线性光学性质。测试结果显示,在1 064nm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-1.23×10-7 m/V和4.35×10-8 m/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Ge/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。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.

关 键 词：半导体复合薄膜 Ge-SiO2薄膜 Ge/Al-SiO2薄膜 非线性吸收 被动调Q 被动锁模 

分 类 号：O484.41[理学—固体物理] TN248.1[理学—物理]