Landau-Zener Tunnelling in Waveguide Arrays

TL;DR

This paper explores Landau-Zener tunnelling in optical waveguide arrays, demonstrating how light can transfer between spectral bands through a step in refractive index, with potential applications in light filtering.

Contribution

It analytically describes the conditions for Landau-Zener tunnelling in waveguide arrays with a refractive index step and proposes a realistic experimental setup.

Findings

Analytical determination of parameter regions for tunnelling

Proposal of a practical experimental configuration

Potential application in optical light filters

Abstract

Landau-Zener tunnelling is discussed in connection with optical waveguide arrays. Light injected in a specific band of the Bloch spectrum in the propagation constant can be transmitted to another band, changing its physical properties. This is achieved using two waveguide arrays with different refractive indices, which amounts to consider a Schr\"odinger equation in a periodic potential with a step. The step causes wave "acceleration" and thus induces Landau-Zener tunnelling. The region of physical parameters where this phenomenon can occur is analytically determined and a realistic experimental setup is suggested. Its application could allow the realization of light filters.