The Effect of Metal Thickness on Si Wire to Plasmonic Slot Waveguide Mode Conversion

TL;DR

This paper explores how metal thickness affects mode conversion efficiency between silicon wire and plasmonic slot waveguides at 1550 nm, providing optimal design parameters for high power transmission.

Contribution

It introduces a taper-based mode converter design optimized for various metal thicknesses, achieving over 90% power transmission, and details mode differentiation methods.

Findings

Over 90% power transmission with optimal dimensions

Effective differentiation between total and main mode power

Design guidelines for reducing insertion loss

Abstract

We investigate mode converters for Si wire to plasmonic slot waveguides at 1550 nm telecom wavelength. The structures are based on a taper geometry. We provide optimal dimensions with more than 90% power transmission for a range of metal (Au) thicknesses between 30-250 nm. We provide details on how to differentiate between the total power and the power in the main mode of the plasmonic slot waveguide. Our analysis is based on the orthogonality of modes of the slot waveguide subject to a suitable inner product definition. Our results are relevant for lowering the insertion loss and the bit error rate of plasmonic modulators.