Core/shell Colloidal Quantum Dots (CQDs) are of interest for nonlinear photonic applications due to their unique properties. In this work, firstly CdTe/CdSe Quasi Type-II Colloidal Quantum Dots with an average core size of 3.54 nm and four different shell thicknesses (1.8 nm, 2.7 nm, 3.2 nm and 3.8 nm) were synthesized and characterized using UV–Vis spectroscopy and Transmission electron microscopy (TEM). Secondly nonlinear optical properties of these structures were determined using Femtosecond Z-scan method at the wavelength of 800 nm. Measured values for two photons absorption coefficients (β) and nonlinear refractive indices (n₂) were found to be on the orders of 10⁻¹¹ cm/W and 10⁻¹⁶ cm²/W, respectively. In addition, the third order nonlinear optical susceptibility values for these structures were calculated to be on the order of 10⁻¹⁰ esu. Quantum dots with thicker shells exhibited faintly higher nonlinear absorption coefficient and slightly lower third order nonlinear optical susceptibility values compared with that of thinner shells. Furthermore, pump power dependant nonlinear optical properties of core/shell nano-structures were investigated and it is observed that two photons absorption coefficient and the third order nonlinear optical susceptibility are pump dependant, while nonlinear refractive indices does not respond to the pump power.

核/壳胶体量子点（CQD）由于其独特的性能而对于非线性光子应用很感兴趣。在这项工作中，首先合成了CdTe / CdSe准II型胶体量子点，其平均核尺寸为3.54 nm，并具有四种不同的壳厚度（1.8 nm，2.7 nm，3.2 nm和3.8 nm），并使用紫外可见光谱进行了表征和透射电子显微镜（TEM）。其次，使用飞秒Z扫描法在800 nm波长下确定这些结构的非线性光学性质。发现两个光子吸收系数（β）和非线性折射率（n ₂）的测量值分别为10 ^-11  cm / W和10 ^-16  cm ^2量级。/ W。另外，这些结构的三阶非线性光学敏感性值经计算为10 ^-10  esu量级。与较薄的壳体相比，具有较厚壳体的量子点显示出稍高的非线性吸收系数，并且具有较低的三阶非线性光学磁化率值。此外，研究了核/壳纳米结构的依赖于泵浦功率的非线性光学性质，并且观察到两个光子吸收系数和三阶非线性光学磁化率与泵浦有关，而非线性折射率不响应泵浦功率。