Bloch oscillations in arrays of helical waveguides

TL;DR

This paper investigates how the geometry of helical waveguides influences optical Bloch oscillations, revealing that waveguide rotation can control oscillation amplitude, direction, and stability, with potential applications in photonic devices.

Contribution

It introduces the effect of helical waveguide geometry on Bloch oscillations, showing how helix radius can manipulate oscillation behavior and stability.

Findings

Helical waveguide rotation affects the band of quasi-energies.

Oscillations can be arrested or reversed by adjusting helix radius.

Near-surface oscillations depend on helix radius in truncated arrays.

Abstract

We study optical Bloch oscillations in the one- and two-dimensional arrays of helical waveguides with transverse refractive index gradient. Longitudinal rotation of waveguides may lead to notable variations of the width of the band of quasi-energies and even its complete collapse for certain radii of the helix. This drastically affects the amplitude and direction of Bloch oscillations. Thus, they can be completely arrested for certain helix radii or their direction can be reversed. If the array of helical waveguides is truncated and near-surface waveguide is excited, helix radius determines whether periodic Bloch oscillations persist or replaced by the irregular near-surface oscillations.