Mode conversion enhancement between silicon micro-slab and plasmonic nano-gap waveguides

TL;DR

This paper demonstrates a novel short, partially-corrugated tapered waveguide design that significantly improves mode coupling efficiency between silicon micro-slab and plasmonic nano-gap waveguides at optical communication frequencies.

Contribution

It introduces a new waveguide structure that enhances mode conversion efficiency, achieving over 80% transmission, and differs from traditional surface plasmon polariton excitation methods.

Findings

Over 80% transmission efficiency achieved numerically.

The corrugated waveguide structure aids on-chip silicon plasmonic device integration.

The coupling mechanism differs from surface plasmon polariton excitation methods.

Abstract

We investigate a short (~1.5{\mu}m) partially-corrugated tapered waveguide structure for mode coupling from a silicon micro-slab to a plasmonic nano-gap waveguide at the optical communication frequency. More than 80% transmission efficiency is reported numerically for the first time. The result indicates that the corrugated waveguide structure should not only be helpful for realizing full on-chip silicon plasmonic devices but also a good choice for mode coupling enhancement from dielectric waveguides to plasmonic waveguides. Meanwhile, we point out that the coupling mechanism reported here is different from that achieved by exciting surface plasmon polaritions (SPPs) at metal surfaces reported in [17] and [18].