Surface plasmon polariton assisted optical pulling force

TL;DR

This paper demonstrates the existence of optical pulling forces near plasmonic interfaces, caused by interference effects and surface plasmon polariton excitation, supported by analytical and numerical analysis.

Contribution

It provides analytical expressions for optical pulling forces on dipolar particles near plasmonic surfaces and extends analysis to larger particles beyond the dipole approximation.

Findings

Optical pulling forces can be achieved near plasmonic interfaces.

Analytical formulas match numerical simulations for dipolar particles.

Surface plasmon polariton excitation enhances the pulling force.

Abstract

We demonstrate both analytically and numerically the existence of optical pulling forces acting on particles located near plasmonic interfaces. Two main factors contribute to the appearance of this negative reaction force. The interference between the incident and reflected waves induces a rotating dipole with an asymmetric scattering pattern while the directional excitation of surface plasmon polaritons (SPP) enhances the linear momentum of scattered light. The strongly asymmetric SPP excitation is determined by spin-orbit coupling of the rotating dipole and surface plasmon polariton. As a result of the total momentum conservation, the force acting on the particle points in a direction opposite to the incident wave propagation. We derive analytical expressions for the force acting on a dipolar particles placed in the proximity of plasmonic surfaces. Analytical expressions for this pulling force are derived within the dipole approximation and are in excellent agreement with results of electromagnetic numerical calculations. The forces acting on larger particles are analyzed numerically, beyond the dipole approximation.