Utilizing multimode interference effects in integrated graded-index optical waveguides for efficient power splitting

Abstract

Purpose

For the realization of optical waveguide components, needed for photonic integrated circuits, multimode-interference based (MMI-based) devices are an excellent component class for the realization of low loss optical splitters. A promising approach to the manufacturing of these components is their embedding in thin glass sheets by ion-exchange diffusion processes, which has not yet been extensively studied. This study aims to significantly enhance the modeling of the diffusion process to support manufacturing of graded-index, MMI-based optical splitters.

Design/methodology/approach

The methods of design and analysis of MMI-based components are based on a step-index refractive index profile. In this work, fundamental correlations between the properties of the manufacturing ion-exchange process and the characteristics of the graded-index, MMI-based components are established. The refractive index profile is calculated with a proprietary solver based on the finite element method. Any further investigation with respect to parameter influence is based on the beam propagation method, specifically a finite difference based, semi-vectorial, wide-angle beam propagation algorithm. The influence of the parameters of the self-imaging effect is investigated. On this basis, different approaches for efficient power splitting with graded-index, MMI-based waveguide components are evaluated.

Findings

Easy approximations – mostly linear – can be found to model the dependencies of the investigated parameters. The resulting graded-index splitters are characterized by their low excess and insertion loss.

Originality/value

These findings are the first step in the direction of the semi-analytical modeling of the respective waveguide components to reduce the numerical effort.

Citation

Roth, J.-P., Kühler, T. and Griese, E. (2018), "Utilizing multimode interference effects in integrated graded-index optical waveguides for efficient power splitting", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 37 No. 4, pp. 1556-1563. https://doi.org/10.1108/COMPEL-09-2017-0374