An Optically Controlled Microscale Elevator Using Plasmonic Janus Particles

作者:Nedev Spas; Carretero Palacios Sol; Kuehler Paul; Lohmueller Theobald; Urban Alexander S*; Anderson Lindsey J E; Feldmann Jochen
来源:ACS Photonics, 2015, 2(4): 491-496.
DOI:10.1021/ph500371z

摘要

In this article, we report how Janus particles, composed of a silica sphere with a gold half-shell, can be not only stably trapped by optical tweezers but also displaced controllably along the axis of the laser beam through a complex interplay between optical and thermal forces. Scattering forces orient the asymmetric particle, while strong absorption on the metal side induces a thermal gradient, resulting in particle motion. An increase in the laser power leads to an upward motion of the particle, while a decrease leads to a downward motion. We study this reversible axial displacement, including a hysteretic jump in the particle position that is a result of the complex pattern of a tightly focused laser beam structure above the focal plane. As a first application we simultaneously trap a spherical gold nanoparticle and show that we can control the distance between the two particles inside the trap. This photonic micron-scale "elevator" is a promising tool for thermal force studies, remote sensing, and optical and thermal micromanipulation experiments.

  • 出版日期2015-4