采用射频磁控反应溅射技术制备了a-Si/SiNx超晶格材料, 并采用热退火技术对材料进行处理。利用吸收光谱和X射线衍射谱对材料进行表征, 结果表明Si层呈现非晶态。为研究材料的三阶非线性光学特性, 对材料进行Z扫描研究, 测量数据表明, 材料的非线性吸收为反饱和吸收, 材料非线性折射率呈现为负值, 该材料的χ(3)的实部为4.57×10-17 C(1.39×10-7 esu), 虚部为1.49×10-17 C (4.48×10-8 esu), 该极化率数值比体硅材料的χ(3)值大5个数量级。对该材料非线性光学产生的机理进行了研究, 认为材料体现出的较强的量子限制效应是非线性极化率增强的主要来源。

Using RF magnetron sputtering technique and thermal annealing, a-Si/SiNx superlattice was fabricated. The absorption measurement and X-ray diffraction show that the Si layer is amorphous. The Z-scan technique is used to research the nonlinear optical properties of a-Si/a-SiNx superlattice. The results indicate that the nonlinear absorption is counter-saturated absorption and the nonlinear refractive index of the sample is a negative value. Moreover, the real and imaginary parts of χ(3) have been calculated to be 4.57×10-17 C(1.39×10-7 esu) and 1.49×10-17 C (4.48×10-8 esu), respectively, which exceeds the value of bulk silicon by more than five order of magnitude. The enhancement of nonlinear refractive index of Si/SiNx superlattice is mainly attributed to intensive quantum confinement.