Modulation of the nonlinear optical response and transient dynamics of CdO/Ag/CdO sandwich-type films

作者：Kun Liu, Zhongguo Li, Jie Li, Wenfa Zhou, Xingzhi Wu, Yu Fang, Junyi Yang, Zhangyang Shao, Run Zhao, Yinglin Song · 发表于：Optics & Laser Technology · 年份：2023 · DOI：10.1016/j.optlastec.2023.109858 · 被引用次数：9 · 研究领域：Nonlinear Optical Materials Studies、Nonlinear Optical Materials Research、Phase-change materials and chalcogenides

Sandwich-type materials with tunable optical response and enhanced optical nonlinearity are of great importance for future nanophotonic devices. Herein, we investigate the third-order nonlinear optical response and transient dynamics of a series of CdO/Ag/CdO sandwich-type films with different Ag sputtering time. SEM images demonstrate that the Ag layer in CdO/Ag/CdO sandwich-type films change from a nanoisland to semi-continuous film with increase of Ag sputtering time. Z-scan measurements indicate that the CdO/Ag/CdO sandwich-type films exhibit huge nonlinear optical response on both femtosecond and picosecond time regime. The maximum nonlinear absorption coefficient (β = 1.605 × 10 -8 m/W) and nonlinear refractive index (n 2 = -6.70 × 10 -15 m 2 /W) of the CdO/Ag/CdO film with 4 min Ag sputtering time are obtained in picosecond Z-scan, which are about 17 and 10 times greater than that of the single-layer CdO, respectively. Transient absorption spectroscopy results confirm the effect of increased CdO/Ag/CdO interface binding on the thermal electron transfer mechanism. A model is proposed to describe the ultrafast dynamic processes in the CdO/Ag/CdO sandwich-type films. Our results indicate the CdO/Ag/CdO sandwich-type films with tailored nonlinear optical properties are highly promising for applications of optical switches devices.