Chiang Wei-Yi, Okuhata Tomoki, Usman Anwar, Tamai Naoto, Masuhara Hiroshi
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University , 1001 Ta Hsueh Rd., Hsinchu 30010, Taiwan.
J Phys Chem B. 2014 Dec 11;118(49):14010-6. doi: 10.1021/jp502524f. Epub 2014 Jun 24.
The development in optical trapping and manipulation has been showing rapid progress, most of it is in the small particle sizes in nanometer scales, substituting the conventional continuous-wave lasers with high-repetition-rate ultrashort laser pulse train and nonlinear optical effects. Here, we evaluate two-photon absorption in optical trapping of 2.7 nm-sized CdTe quantum dots (QDs) with high-repetition-rate femtosecond pulse train by probing laser intensity dependence of both Rayleigh scattering image and the two-photon-induced luminescence spectrum of the optically trapped QDs. The Rayleigh scattering imaging indicates that the two-photon absorption (TPA) process enhances trapping ability of the QDs. Similarly, a nonlinear increase of the two-photon-induced luminescence with the incident laser intensity fairly indicates the existence of the TPA process.
光镊与操控技术的发展一直进展迅速，其中大部分进展集中在纳米尺度的小颗粒上，用高重复率超短激光脉冲序列和非线性光学效应取代了传统的连续波激光器。在此，我们通过探测光镊中2.7纳米大小的碲化镉量子点（QDs）的瑞利散射图像和双光子诱导发光光谱的激光强度依赖性，评估了高重复率飞秒脉冲序列对其进行光镊操作时的双光子吸收情况。瑞利散射成像表明双光子吸收（TPA）过程增强了量子点的捕获能力。同样，双光子诱导发光随入射激光强度的非线性增加也充分表明了TPA过程的存在。
