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使用10 ns脉冲调QNd∶YAG激光器Z-scan技术测量了化学合成的无掺杂硫化锌量子点(QDs)以及掺Mn2+硫化锌量子点(QDs)的非线性光学特性,并使用透射电镜技术(TEM)以及X射线衍射法(XRD)表征合成材料的纳米结构。在室温下,分别利用UV-VIS分光光度计和分光荧光计测量了人工合成QDs胶体溶液的线性光学吸收特性以及光致发光的发射特性。样品的吸收特性表明,由于量子限制效应的影响,样品的截止吸收低于硫化锌的截止吸收。样品的光致发光特性显示,掺Mn2+的硫化锌样品显示出明显的光致发光现象,发射峰大约在580 nm;而无掺杂的硫化锌样品在紫外区辐射,发射峰大约在365 nm。对样品的UV-VIS吸收特性分析和TEMXRD分析表明,硫化锌样品的平均粒度(半径)大约为1.2 nm。分析开放光圈(OA)Z-scan技术得到的实验数据,发现在1 064 nm处两种试验样品都会发生四光子吸收(FPA)现象。拟合实验数据得到了两种试验样品的FPA系数以及FPA横截面,结果表明,ZnS QD的FPA横截面的计算值是4.9×10-106cm8.s3.photon-3,比硫化锌的FPA横截面大了5个数量级,而且人工合成的ZnS QD也有光学限制的性质。掺Mn2+离子的样品具有大的FPA横截面和在可见光区有高的发光效率这两个特点,使得该材料适合用于多光子荧光成像。
The nonlinear optical characteristics of chemically synthesized undoped ZnS quantum dots (QDs) and Mn2 + doped ZnS quantum dots (QDs) were measured using a 10 ns pulsed QNd: YAG laser Z-scan technique. Transmission electron microscopy TEM) and X-ray diffraction (XRD) to characterize the nanostructures of synthetic materials. The linear optical absorption properties and photoluminescence emission properties of the synthesized QDs colloidal solution were measured by UV-VIS spectrophotometer and spectrofluorimeter respectively at room temperature. The absorption characteristics of the sample show that the cut-off absorption of the sample is lower than the cut-off absorption of zinc sulfide due to the effect of the quantum confinement effect. The photoluminescence characteristics of the samples show that Zn2 + -doped ZnS samples show obvious photoluminescence with an emission peak at about 580 nm, while undoped ZnS samples emit in the UV region with an emission peak at about 365 nm. Analysis of the UV-VIS absorption characteristics and TEMXRD analysis of the sample showed that the average particle size (radius) of the zinc sulfide sample was about 1.2 nm. Analysis of open aperture (OA) Z-scan technology experimental data obtained at 1064 nm in both test samples will occur four-photon absorption (FPA) phenomenon. Fitting the experimental data obtained the FPA coefficient and the FPA cross section of the two test samples. The results show that the FPA cross section of the ZnS QD is 4.9 × 10 -106 cm 8.s3.photon-3, which is larger than the FPA cross section of the zinc sulfide Large by 5 orders of magnitude, and synthetic ZnS QDs also have optical limiting properties. The Mn2 + ion-doped sample has both large FPA cross section and high luminous efficiency in the visible region, making the material suitable for multi-photon fluorescence imaging.