Numerical Analysis of Laterally and Vertically Coupled Hybrid Plasmonic Modes in Silicon Tip

Abstract

Hybrid plasmonic waveguides have emerged as one of the most emerging tools for long-range subwavelength optical guidance. We propose the coupling of a hybrid plasmonic (HP) mode into a silicon tip. The HP mode is made to confine in the silicon tip through lateral as well as a vertical coupling, which provides moderately good field enhancement with long-range propagation. The lateral coupling exhibits a field enhancement of more than 200 in a silicon tip with a propagation length of 110 μm. Field enhancement in the vertically coupled case is 25 with a propagation length of 1.1 mm. In both cases, mode area remains around 50–60 nm2. In addition, both structures show broadband propagation of HP modes where propagation length remains long over a broad range wavelength. The proposed waveguide structures can be useful in realizing nanophotonic devices for broad range of applications including spectroscopy, optical fiber communication and bio-chemical sensing. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.