Lateral Optical Forces on Linearly-Polarized Emitters near a Reciprocal Substrate

TL;DR

This paper theoretically explores lateral optical forces on dipole emitters near reciprocal substrates, revealing conditions under which such forces vanish or appear, especially highlighting a novel recoil force for combined electric and magnetic dipoles near tilted uniaxial dielectrics.

Contribution

It demonstrates that linearly polarized electric dipoles experience no lateral force near reciprocal substrates, but a superposition of electric and magnetic dipoles can induce a recoil force in specific anisotropic conditions.

Findings

Lateral forces vanish for linearly polarized electric dipoles near reciprocal substrates.

A recoil force can occur for combined electric and magnetic dipoles near tilted uniaxial dielectrics.

Recoil force is oriented perpendicular to the interface normal and substrate optical axis.

Abstract

We theoretically investigate the emergence of lateral (recoil) forces acting on generic dipole-type emitters in the vicinity of a reciprocal translation-invariant substrate. Surprisingly, we find that for linearly-polarized electric dipoles the lateral force invariably vanishes, independent of the anisotropy (e.g., tilted optical axes) or chirality of the substrate. We identify a novel opportunity to have a recoil force relying on a superposition of two linearly-polarized and collinear electric and magnetic dipoles. Counterintuitively, it is shown that when such an emitter stands above a uniaxial dielectric half-space with tilted optical axes it may experience a recoil force oriented along the direction perpendicular to the plane defined by the interface normal and the substrate optical axis.