Design of compact mode splitters using identical coupled waveguides with slots

S L Hada,B M A Rahman

doi:10.1364/osac.2.000848

Abstract

In the past, multimode transmission through fibers has not been considered a preferred means of signal propagation due to the intermodal dispersion, which limits the data rate. However, recently, there has been an interest in using different modes as individual channels to increase the overall data rate. However, the challenging task in implementing such a system is that each individual mode has to be excited separately without mixing, and these should remain separated even at the bents and splices, and finally, they need to be collected separately. In this paper, design and optimization of a compact optical mode splitter by introducing a small slot in a silicon nanowire waveguide is demonstrated by employing a full-vectorial finite element method. The authors report here that by creating a slot within a waveguide, the desired coupling length ratio of 1:2 between the fundamental and the second modes can be obtained. The waveguide junctions have also been analyzed by using a rigorous least squares boundary residual method to study power transfer efficiency and effect of fabrication tolerances.

Highlights

The rapidly increasing demand for Internet bandwidth created a challenge to the network provider to cater for such bandwidth requirement and satisfy the transmission capacity by using single mode optical fiber
An alternative approach could be the adaptation of multiple-input multiple-output signal processing over multimode fibers (MMFs) [4]
First, we focused on the effect of mesh variation as the Finite Element Method (FEM) solution accuracy can critically depend on this parameter

Summary

Introduction

The rapidly increasing demand for Internet bandwidth created a challenge to the network provider to cater for such bandwidth requirement and satisfy the transmission capacity by using single mode optical fiber. An alternative approach could be the adaptation of multiple-input multiple-output signal processing over multimode fibers (MMFs) [4]. In this case, mode selective couplers [5] or filters [6] can be used to excite different signal channels as different modes of a MMF and form independent data channels in a MMF [7]. In order to circumvent this problem, there is a requirement to excite the modes individually and to design components such as a mode splitter, which can separate different modes and so can treat them as independent transmission channels

Theoretical background

Results: directional coupler as a mode splitter

Power transfer calculation

Results: power transfer

Findings

Conclusion