Efficient optical trapping of CdTe quantum dots by femtosecond laser pulses
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AbstractThe 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.
SponsorsThis work was supported the Ministry of Education of Taiwan (MOE-ATU Project; National Chiao Tung University) and the National Science Council of Taiwan (Grant NSC 100-2113-M-009-001). H.M. also thanks the Foundation of the Advancement for Outstanding Scholarship of Taiwan. The reviewers are also acknowledged for their valuable comments and advice.
PublisherAmerican Chemical Society (ACS)