Efficient Plasmonic 2D Arrangement and Manipulation System, Suitable for Controlling Particle–Particle Interactions

Investigating interactions between biological or artificial micro and nanoparticles (NPs) are vital for understanding processes such as intercellular communications, and quantum and optical effects in an array of NPs. In this line of research, methods to precisely trap and manipulate NPs are essential to investigate such inter-particle interactions. Exciting higher order counter-propagating leaky surface plasmon modes (LSPMs) of a thin gold stripe, we present a simple and efficient method to arrange NPs into a two-dimensional (2D) periodic pattern, allowing precise control over inter-particle interactions. We demonstrate that the 2D lattice of traps is generated by interference of totally reflected surface plasmons from the gold stripe edges and also interference of two counter-propagating LSPMs. Analytical calculations and numerical simulations are in good agreement with the observed modal behavior of LSPMs. Due to the modal dependency of LSPMs on the incident wavelength, we show that in this system different inter-particle distance with nanometer resolution can be achieved by adjusting the wavelength of the incident laser beams. Moreover, we show that the trapped NP array shows waveguiding behavior, enhances the mode intensities and the resulted potential wells consequently. We expect that this self-induced enhancement of trapping efficiency is beneficial for the periodic arrangement of NPs and array formation. The proposed approach implemented in a simple plasmonic optophoresis system, opens the possibility to develop integrated optical manipulation chips, which allows simple and low-cost approach for controlling and studying the inter-particle interactions. Furthermore, the proposed approach is also promising for controllable assembling of NPs without the need for complicated and time consuming nano-lithography techniques.