Optical Tweezers based on Nano-focusing of Coupled Surface Plasmons in two Gold Strips

Document Type : Original Article

Authors

1 Faculty of Electrical and Computer Engineering, Hakim Sabzevari University, P.O. Box 397, Sabzevar 9617976487,Iran.

2 Faculty of Electrical and Computer Engineering, Hakim Sabzevari University, P. O. Box 397, Sabzevar 9617976487, Iran

Abstract

In this paper an optical tweezer with the ability to manipulate and sense nanoparticles using the coupling of surface plasmons of two gold strips and its nano-focusing is proposed. To investigate the performance of the proposed structure, at first the plasmonic modes have been calculated by the finite difference Eigen-mode method and then using the finite-difference time-domain method and calculating Maxwell stress tensor the optical forces have been obtained. The simulation results show that the proposed structure has the ability to trap and manipulate nanoparticles. Due to the dependency of the trapping sites on the incident light frequency, the proposed structure, in addition to the ability to move nanoparticles by mechanical movement of the optical tweezer, can also move nanoparticles by tuning the frequency. Also, the simulation results show that due to the dependency of the reflected power on the refractive index of the trapped nanoparticle, the trapped nanoparticle can be sensed by analysing the reflected power. We believe this structure can be used in various fields, especially in biological sciences, to study and move nanoparticles.

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