Efficient Optical Trapping of CdTe Quantum Dots by Femtosecond Laser Pulses

Abstract

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.

All-dielectric nanotweezers for trapping and observation of a single quantum dot

“…This is extremely small, indicating insignificant modification to optical forces via the optical Kerr effect [42]. We note however that it has been reported that, in conventional optical tweezers with illumination from a femtosecond laser, the TPA process can enhance the trapping of QDs [30]. The use of femtosecond laser pulses with all-dielectric nanoantenna tweezers for the trapping of QDs and other nanomaterials might be an interesting topic for the future study.…”

“…At present, there has been much interest in using optical tweezers to trap nanomaterials in solution for a variety of reasons, including to localize these materials to facilitate their characterization via spectroscopy [12,13]. It has been demonstrated that conventional single light-based optical tweezers can be utilized to trap individual QDs and aggregates of QDs [27][28][29][30][31][32][33]. This prompts the question of whether QDs can be trapped using nanotweezers supported by surface plasmons and other methods, due to the potential advantages that include tighter spatial confinement, lower optical power requirements and integration with sensing.…”

In situ reflection imaging and microspectroscopic study on three-dimensional crystal growth of L-phenylalanine under laser trapping

“…This assembly formation was demonstrated for plasmonic nanoparticles [6][7][8] , polymeric nanospheres 9) , semiconductor quantum dots 10,11) , polymers [12][13][14] , proteins [15][16][17] , and amino acids 18) .…”

Optical forces of focused femtosecond laser pulses on nonlinear optical Rayleigh particles

“…It should be noted that the optical force originating from the nonlinear polarization becomes significant and cannot be neglected if the trapped particles exhibit nonlinear optical effects. Moreover, the experimental observations have revealed that the nonlinear optical effects could enhance the optical force [8,16] or modify the optical trapping potential [13].To quantitatively appraise the trapping ability, the optical force exerted on a spherical nanoparticle arising from the linear polarization has been calculated using various approaches, such as Rayleigh scattering formulae [1], Maxwell's stress tensor [17], and discrete dipole approximation [18]. For a nonlinear optical Rayleigh particle, however, the optical force unambiguously originates from the contribution of both the linear and nonlinear induced polarizations.…”

“…It should be noted that the optical force originating from the nonlinear polarization becomes significant and cannot be neglected if the trapped particles exhibit nonlinear optical effects. Moreover, the experimental observations have revealed that the nonlinear optical effects could enhance the optical force [8,16] or modify the optical trapping potential [13].…”