Graphene-based plasmonic force switch

Abstract

We take advantage of a Kretschmann configuration to design a plasmonic force switch. It consists of a prism/Au/SiO2 stack topped by a gated graphene sheet, as an electrically active optofluidic particle sorting system. We show that using a small gate voltage, one can switch the plasmon-wave induced force on a target particle, and hence its velocity. Simulations show that by electrical tuning of the graphene electrochemical potential in a narrow range of ∼65 meV—i.e., equivalent to an applied gate voltage of ∼4.3 V—the graphene surface plasmons can absorb the Au surface plasmons, switching off the plasmonic force exerted on the target particle with an ON/OFF ratio of more than 20. Numerical results also show that the maximum sensitivity of the particle's velocity to the graphene electrochemical potential is ∼1136 μm/eV-s. The proposed electrically active plasmonic force switch offers opportunities in developing tunable on-chip optical micromanipulations with multiple parallel functionalities and low power consumption.