Design of compact mode splitters using identical coupled waveguides with slots

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.

Inverse design of highly efficient and broadband mode splitter on SOI platform

“…In Ref. [14], a dual-mode mode splitter was designed by introducing small slots in the silicon waveguide to form a symmetric directional coupler (DC), achieving CT of < − 15 dB and low IL of <0.1 dB for the entire C-band. Furthermore, a dual-mode splitter for separating TM 0 and TM 1 modes was developed using a bridged subwavelength grating-assisted (BSWG) DC and a mode filter, with CT of < − 15 dB and IL of <1.8 dB for a bandwidth of 84 nm [15] .…”