Zhu Baohua, Wang Fangfang, Liao Chen, Zhang Huichao, Zhang Jiayu, Cui Yiping, Ye Yonghong, Gu Yuzong
Opt Express. 2019 Feb 4;27(3):1777-1785. doi: 10.1364/OE.27.001777.
Tuning a semiconductor nanomaterial with large two-photon absorption cross section in the near-infrared wavelength and investigating the correlation and origins between its size and third-order nonlinear optical properties are very important in possible applications. In this work, CdSe quantum dots (QDs) with various sizes were successfully prepared, and their size-confined third-order nonlinear optical properties were investigated by Z-scan technique with 100 fs laser pulses at 800 nm wavelength. Both the two-photon absorption and nonlinear refraction were enhanced about 8.1 times with size decrease and then weakened to 2 times with further size decrease. QDs with the diameter of 4.9 nm had the largest nonlinear optical susceptibility of 7.8 × 10 esu. The effects of photoinduced dipole moment and local electric field were proposed to explain this trend. And the intrinsic dipole moment and defects in CdSe QDs also had an effect on this nonlinear process.
在近红外波长下调整具有大二阶非线性吸收截面的半导体纳米材料，并研究其尺寸与三阶非线性光学性质之间的相关性及起源，在可能的应用中非常重要。在这项工作中，成功制备了各种尺寸的CdSe量子点（QDs），并通过Z扫描技术，在800 nm波长的100 fs激光脉冲下研究了其尺寸受限的三阶非线性光学性质。随着尺寸减小，双光子吸收和非线性折射均增强约8.1倍，然后随着尺寸进一步减小减弱至2倍。直径为4.9 nm的量子点具有最大的非线性光学极化率，为7.8×10 esu。提出了光致偶极矩和局部电场的影响来解释这一趋势。并且CdSe量子点中的固有偶极矩和缺陷也对这一非线性过程有影响。
