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以Nd:YAG锁模激光器二倍频532nm的激光作激发光,利用Z-扫描技术研究了CdSeS量子点的光学非线性特性。实验结果表明,CdSeS量子点在532nm光激发下具有很大的非线性吸收效应,吸收光谱和荧光光谱表明,CdSeS量子点的非线性吸收效应来自于双光子吸收。与已经有报道的量子点相比较发现CdSeS量子点产生双光子吸收效应的阈值为1.36GW/cm2,非线性折射率达10-8esu量级,平均双光子吸收截面为25960GM。CdSeS量子点的这些优异光学非线性特性可使其广泛地应用在生物成像、荧光标记、全光光开关及光限幅等方面。
The optical nonlinearity of CdSeS QDs was investigated by using Z-scan technique with a Nd: YAG mode-locked laser with double frequency of 532nm as excitation light. The experimental results show that the CdSeS quantum dots have a large nonlinear absorption effect under 532 nm excitation. The absorption and fluorescence spectra of CdSeS quantum dots show that the nonlinear absorption of CdSeS QDs comes from two-photon absorption. Compared with the reported quantum dots, the threshold of the two-photon absorption effect of CdSeS quantum dots is found to be 1.36GW / cm2, the nonlinear refractive index is on the order of 10-8esu, and the average two-photon absorption cross-section is 25960GM. These excellent optical nonlinearities of CdSeS quantum dots make them widely used in biological imaging, fluorescent labeling, all-optical switch and optical limiting.