量子点尺寸对硒化银及其石墨烯复合物光学非线性的影响  

Effect of Quantum Size on Optical Nonlinearity of Silver Selenide Quantum Dots and Their Graphene Composites

作　　者：刘阳 杨婕娟 朱宝华 张一民 顾玉宗[1] LIU Yang;YANG Jiejuan;ZHU Baohua;ZHANG Yimin;GU Yuzong(Henan University School of Physics and Electronics,Henan Kaifeng 475004,China;Henan University School of Software,Henan Kaifeng 475004,China)

机构地区：[1]河南大学物理与电子学院,河南开封475004 [2]河南大学软件学院,河南开封475004

出　　处：《河南大学学报（自然科学版）》2022年第6期699-709,共11页Journal of Henan University:Natural Science

基　　金：国家自然科学基金资助项目(61875053);河南省优秀青年科学基金项目(202300410047)。

摘　　要：为探明量子点尺寸对硒化银量子点(Ag2SeQDs)及其与石墨烯复合材料(GAS)非线性光学性质的影响,本文采用简单的化学方法,分别制备了尺寸为4.2~16.9 nm的Ag2SeQDs,以及10.3~30.0 nm的Ag2SeQDs/石墨烯复合材料(GAS),采用XRD、Raman、FTIR及TEM等手段表征了所制样品的结构与形貌.采用单光束Z-扫描技术,以波长为532 nm、脉宽为30 ps、重复频率为10 Hz的激光为照射光源,测量了各样品在开孔和闭孔条件下的归一化透过率,计算得到了它们的非线性吸收和非线性折射等系数.结果表明,Ag2SeQDs具有双光子吸收和正的非线性折射性质,且双光子吸收和非线性折射系数随着量子尺寸的减小而增大;复合材料GAS具有饱和吸收和正的非线性折射性质,且相比单体石墨烯得到显著增强,增强因子随Ag2SeQDs尺寸的减小而减小.分别采用双带近似模型及电荷转移机制,对Ag2SeQDs及GAS材料随量子点尺寸变化的非线性响应进行了理论分析.该研究为Ag2SeQDs及GAS材料的光学非线性的进一步调控及在光子器件上的应用奠定了基础.To explore the effect of quantum dot size on the nonlinear optical properties of silver selenide quantum dots(Ag2SeQDs) and their composite materials with graphene, Ag2SeQDs with sizes ranging from 4.2 to 16.9 nm and the composites of Ag2SeQDs with the size of 10.3~30.0 nm with graphene(GAS) were prepared by a facile chemical method. The structure and morphology of the samples were characterized by XRD, Raman, FTIR and TEM. The nonlinear absorption and nonlinear refraction coefficients of each sample were measured by the single beam Z-scan technique using a laser at the wavelength of 532 nm, pulse width of 30 ps, and the repetition rate of 10 Hz. The results show that Ag2SeQDs has two-photon absorption and positive nonlinear refraction, and the two-photon absorption and refraction coefficients increase with the decrease of quantum size. The composite GAS has enhanced saturable absorption and positive nonlinear refraction compared with single graphene, and the enhancement factor decreases with the decrease of quantum dot size. The nonlinear response with the quantum size of Ag2SeQDs and GAS materials were theoretically analyzed by using the double band approximate model and charge transfer mechanism, respectively. This study lays a foundation for further regulating the optical nonlinearity of Ag2SeQDs and GAS as well as their applications in photonic devices.

关 键 词：量子点 硒化银 石墨烯 非线性光学性质 Z-扫描 

分 类 号：O437[机械工程—光学工程]