CdSe量子点的线性和非线性光学特性

主要从实验和理论两个方面，探讨了强受限尺寸区域内不同尺寸对CdSe量子点线性和非线性光学性质的影响.用吸收光谱研究了量子点尺寸与吸收峰之间的关系，用皮秒Z扫描技术研究了共振和非共振情况下(激发光波长分别为532和1064nm)，尺寸与三阶非线性极化率之间的关系.基于电子能量状态理论和局域场增强理论对量子点进行分析，得到了CdSe不同尺寸的三阶非线性效应，研究了尺寸对量子点非线性光学性质的影响.结果表明，由激发态粒子数布局改变和纳米颗粒增大引起的非线性共振增强效应相当，二者共同作用使得三阶极化率增强20倍左右，且用532nm的共振频率激发4.3nm CdSe量子点时，χ⁽³⁾具有最大值2.0×10^-11esu.关键词：CdSe量子点三阶非线性Z扫描')" href="#">Z扫描量子限域效应

Linear and nonlinear optical properties of CdSe quantumn dots

On the basis of measurement and theoretical analysis, the linear and nonlinear optical properties of the CdSe quantumn dots with different nanoparticle sizes were investigated. The relation between the nanoparticle size and the absorption peak of CdSe quantumn dots was characterized by UV-VIS-NIR spectroscopy, and the dependence of third-order nonlinear susceptibility of quantumn dots on nanoparticle size was investigated by picosecond Z-scan technique with different excitation wavelengths (532nm and 1064nm,resp.). The analysis of optical properties of the films was carried out using the theory of localized field enhancement. The experimental and theoretical results showed the dependence of third-order nonlinear susceptibilities χ⁽³⁾ on the CdSe nanoparticle size. With CdSe nanoparticle size around 4.3nm and the excitation wavelength of 532nm, which was close to the resonance, the third-order nonlinear susceptibility χ⁽³⁾ showed a maximum value of 2.0×10^-11 esu.