Slow-light enhanced optical forces between longitudinally shifted photonic-crystal nanowire waveguides

TL;DR

This paper demonstrates that introducing a longitudinal shift in photonic-crystal nanowire waveguides allows for tunable optical forces, including switching from repulsive to attractive forces and enabling longitudinal forces through symmetry breaking.

Contribution

It introduces a method to control optical forces in photonic-crystal waveguides via longitudinal shifting, revealing new force behaviors near the photonic band-edge.

Findings

Transverse force can be tuned from repulsive to attractive.

Symmetry breaking enables longitudinal forces.

Force suppression occurs at specific shift values.

Abstract

We reveal that slow-light enhanced optical forces between side-coupled photonic-crystal nanowire waveguides can be flexibly controlled by introducing a relative longitudinal shift. We predict that close to the photonic band-edge, where the group velocity is reduced, the transverse force can be tuned from repulse to attractive, and the force is suppressed for a particular shift value. Additionally the shift leads to symmetry breaking that can facilitate longitudinal forces acting on the waveguides, in contrast to unshifted structures where such forces vanish.