| 不同核心尺寸及壳层厚度CdTe/CdS量子点非线性光学及超快动力学特性 |
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| 作者姓名： | Chang Qing Tan Hengyu Meng Tianming |
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| 作者单位： | 1.浙江传媒学院 媒体工程学院，浙江 杭州 310018 |
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| 摘 要： | CdTe核壳结构半导体量子点具有特殊的非线性光学和超快动力学特性，使其在太阳能电池、光电子器件、生物标记和光纤传感领域有着广泛的应用前景。主要研究了6种不同核心尺寸、不同壳层厚度CdTe/CdS核壳结构半导体量子点的非线性光学和超快动力学特性。在波长400 nm、脉冲宽度130 fs激光脉冲作用下采用Z-Scan技术测量了样品的非线性吸收和非线性折射系数。实验结果表明，CdTe/CdS核壳结构量子点的壳层厚度影响非线性吸收和非线性折射特性，非线性吸收和非线性折射系数均随壳层厚度增加而增大。核心尺寸主要影响非线性吸收特性，非线性吸收系数随核心尺寸的增大而减小。在波长400 nm、脉冲宽度130 fs、频率1 kHz、单脉冲能量400 nJ条件下采用飞秒时间分辨瞬态吸收光谱技术测量了样品的超快动力学特性，得到了瞬态吸收光谱和超快动力学曲线。结果表明漂白信号上升过程时间随壳层厚度的增加而变大。快过程衰减时间随着壳层厚度的增加而变大，同时随着核心尺寸增加而增长；慢过程衰减时间随着壳层厚度的增加而变大。研究揭示了CdTe核壳结构量子点的核心尺寸、壳层厚度对非线性光学和超快动力学的影响规律，为核壳结构量子点的制备和光物理特性研究提供了理论基础。
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| 关 键 词： | CdTe/CdS量子点 非线性吸收 非线性折射 超快动力学 激子寿命 |
| 收稿时间： | 2020-10-06 |
Nonlinear optics and ultrafast dynamics characteristics of CdTe/CdS quantum dots with different core sizes and shell thickness |
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| Chang Qing,Tan Hengyu,Meng Tianming.Nonlinear optics and ultrafast dynamics characteristics of CdTe/CdS quantum dots with different core sizes and shell thickness[J].Infrared and Laser Engineering,2021,50(2):20200342-1-20200342-10. |
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| Affiliation: | 1.College of Media Engineering, Communication University of Zhejiang, Hangzhou 310018, China2.Beijing Institute of Metrology, Beijing 100029, China3.College of Electronic Engineering, Heilongjiang University, Harbin 150080, China |
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| Abstract: | CdTe core-shell semiconductor quantum dots are being widely explored due to their special nonlinear optics and ultrafast dynamics characteristics that include solar cells, optoelectronic devices, biological labeling, and optics fiber sensing fields. In this work, the six kinds of CdTe/CdS core-shell quantum dots were researched in the different core sizes and shell thicknesses for the nonlinear optics and ultrafast dynamics characteristics. The nonlinear absorption and refraction coefficients of the samples were measured by using Z-scan technology under the action of 400 nm wavelength and 130 fs laser pulse width. The experimental results show that the shell thickness of CdTe/CdS core-shell quantum dots affects the nonlinear absorption and refraction characteristics, in which the nonlinear absorption and refraction coefficients increase with the shell thickness. And the core size mainly affects the nonlinear absorption characteristics, while the nonlinear absorption coefficient decreases with the increase of the core size. At the same time, femtosecond time-resolved transient absorption spectroscopy technology was used to measure the ultrafast dynamics characteristics of the samples under the conditions of 400 nm wavelength, 130 fs pulse width, 1 kHz frequency, and 400 nJ single-pulse energy. The transient absorption spectra and ultrafast dynamics curves were obtained. The results suggest that the rising time of bleaching signal increases with the shell thickness. The decay time of the fast process increases with the shell thickness and core size. The decay time of the slow process increases with the shell thickness. The research reveals the influence of the core size and shell thickness of CdTe core-shell quantum dots on the nonlinear optics and ultrafast dynamics, providing a theoretical basis for the preparation of core-shell quantum dots and the research of the photophysical properties. |
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