Authors: Zaoshan Huang Qiaofeng Dai Sheng Lan Shaolong Tie
Publish Date: 2014/08/19
Volume: 9, Issue: 6, Pages: 1491-1500
Abstract
We investigate numerically the modification of the nonlinear optical properties of a nanoantenna in the trapping of nanoparticles NPs by using both the discrete dipole approximation method and the finitedifference timedomain technique The nanoantenna which is formed by two gold nanorods GNRs aligned end to end and separated by a small gap can emit strong twophotoninduced luminescence TPL under the excitation of a femtosecond laser light which is resonant with its longitudinal surface plasmon resonance In addition the excited antenna can stably trap small NPs which in turn induce modifications in the emitted TPL These two features make it a promising candidate for building highly sensitive detectors for NPs of different materials and sizes It is demonstrated that sensors built with antennas possess higher sensitivities than those built with single GNRs and nanorodbased antennas are more sensitive than nanoprismbased antennas In addition it is found that the trapping probability for a second NP is significantly reduced for the antenna with a trapped NP implying that trapping of NPs may occur sequentially A relationship between the TPL of the system antenna + NP and the optical potential energy of the NP is established enabling the extraction of the information on the optical potential energy and optical force by recording the TPL of the system It is shown that the sequential trapping and releasing of NPs flowing in a microfluid channel can be realized by designing two different antennas arranged closelyThe authors acknowledge the financial support from the National Natural Science Foundation of China Grant Nos 51171066 and 11374109 the Ministry of Education of China Grant No 20114407110002 and the project for highlevel professionals in the universities of Guangdong province China QF Dai would like to thank the Guangzhou science and technology project Grant No 2011J2200080
Keywords: