非晶态InSb薄膜的光学非线性特性及其超分辨效应  

Optical Nonlinear Characteristics of Amorphous InSb Thin Film and Its Super-Resolution Effect

作　　者：蔡晓林[1,2] 魏劲松[1] 严辉[1,2] 

机构地区：[1]中国科学院上海光学精密机械研究所,上海201800 [2]中国科学院大学,北京100049

出　　处：《光学学报》2013年第9期295-302,共8页Acta Optica Sinica

基　　金：国家自然科学基金(51172253;61137002)

摘　　要：用磁控溅射法制备了K9基片/非晶态InSb/ZnS-SiO2样品。利用椭圆偏振光谱仪对非晶态InSb薄膜的光学常数进行了测量,利用傅里叶变换红外光谱仪得到光学带隙为0.26eV。采用改进的Z-扫描装置对405nm波长的非线性吸收和非线性折射进行了测量。结果表明非晶态InSb薄膜表现出饱和吸收和自聚焦特性,有效非线性吸收系数为-3.73×10-2 m/W,非线性折射率为6.64×10-9 m2/W。根据非线性吸收系数,计算了非线性吸收截面的面积,与相关文献的报道非常接近。基于对非晶态InSb薄膜在405nm波长的变温椭偏测试,讨论了热效应对非线性的贡献。分析表明非线性饱和吸收特性主要来源于纳秒脉冲激光作用下的热效应,而非线性折射特性是电子受激跃迁过程导致的。对饱和吸收特性诱导的超分辨效应进行了模拟,结果表明InSb薄膜的非线性吸收特性可以有效减小透射光斑的大小。Samples of amorphous-InSb/ZnS-Si02 structure are deposited on K9 glass substrate with magnetron sputtering method in this study. Optical constants of amorphous InSb thin films are measured by a spectroscopic ellipsometer. The optical band gap is determined to be 0.26 eV by Fourier transform infrared spectroscopy. The nonlinear absorption and nonlinear refraction of the amorphous InSb thin films are measured through well-established Z-scan method at the wavelength of 405 nm. Results show that the amorphous InSb thin films show the characteristics of saturable absorption and self-focusing, the nonlinear absorption coefficient is -3.73×10^-2m/W, and the nonlinear refractive index is 6. 64 × 10^-9 m^2/W. Based on the nonlinear absorption coefficient, the nonlinear absorption cross section is calculated, which is very close to the reported value of related literature. The thermo- optical effect is investigated by variable temperature ellipsometry method at the wavelength of 405 nm. Analysis indicates that the nonlinear saturable absorption mainly stems from nanosecond laser-induced thermal effect, whereas the self-focusing refraction mainly results from electronic nonlinearity, respectively. The super-resolution effect induced by the saturable absorption characteristic is simulated, and the results show that the nonlinear absorption effect of the amorphous InSb thin films can effectively reduce the size of the transmission spot.

关 键 词：薄膜 光学非线性 Z-扫描 非晶态InSb 超分辨 光存储 

分 类 号：O472[理学—半导体物理]