Complete achromatic optical switching between two waveguides with a sign flip of the phase mismatch

TL;DR

This paper introduces a robust, achromatic optical switching method between two waveguides using a hyperbolic-secant coupling profile and a phase mismatch sign flip, with potential extension to three-waveguide arrays.

Contribution

It provides an analytic solution for achromatic all-optical switching with a novel phase mismatch sign flip technique, enhancing robustness against parameter variations.

Findings

Achromatic switching is achieved with high robustness.

Analytic solution for electric field propagation is derived.

Extension to three-waveguide arrays enables achromatic beam splitting.

Abstract

We present a two-waveguide coupler which, realizes complete achromatic all-optical switching. The coupling of the waveguides has a hyperbolic-secant shape while the phase mismatch has a sign flip at the maximum of the coupling. We derive an analytic solution for the electric field propagation using coupled mode theory and show that the light switching is robust again small-to-moderate variations in the coupling and phase mismatch. Thus, we realize an achromatic light switching between the two waveguides. We further consider the extended case of three coupled waveguides in an array and pay special attention to the case of equal achromatic light beam splitting.