Ultra‐compact and ultra‐broadband hybrid plasmonic‐photonic vertical coupler with high coupling efficiency, directivity, and polarisation extinction ratio

Hamed Pezeshki,Eric C Larkins,Amanda J Wright

doi:10.1049/ote2.12063

Hamed Pezeshki, Eric C Larkins + Show 1 more

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https://doi.org/10.1049/ote2.12063

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Abstract

An ultra-compact, ultra-broadband vertical coupler for dense photonic integrated circuits is reported with a 1.07 × 0.62 μm2 wavelength-scale footprint. This hybrid plasmonic-photonic coupler uses a unique two-plane plasmonic nanoantenna array on a silicon-on-insulator waveguide. The in- and out-of-plane interference of the multipole moments and dual-feed nanoantennas results in efficient, unidirectional coupling. Finite-element simulations show that, for a 0.8 μm diameter Gaussian beam, the maximum coupling efficiency (CE) is −3.4 dB across the telecommunication C-, L- and U-bands with a 3-dB bandwidth of 230 nm. The CE is > 9 dB higher than recently reported ultra-compact plasmonic couplers. The maximum directivity and polarisation extinction ratio across the C- to U-bands are 9.2 and 24.1 dB, respectively. Finally, as an out-coupler, it has a vertical directivity of >8.5 dB, enabling its use for vertical optical interconnects between two vertically separated circuits.

Highlights

Optical couplers are used extensively for telecommunication applications as a component to couple light into photonic integrated circuits (PICs)
This work reports on the design of a hybrid plasmonic‐photonic vertical coupler (HVC) with an ultra‐compact footprint and one‐step dielectric waveguide coupling
This paper presents a new class of HVC, that is, 2P‐numerical aperture (NA) HVC, comprised of a 2P‐NA coupled directly to a SOI waveguide

Summary

Introduction

Optical couplers are used extensively for telecommunication applications as a component to couple light into photonic integrated circuits (PICs). This work reports on the design of a hybrid plasmonic‐photonic vertical coupler (HVC) with an ultra‐compact footprint and one‐step dielectric waveguide coupling This VC is based on a unique two‐plane plasmonic nanoantenna (PNA) array (2P‐NA) with a wavelength‐scale footprint. The key innovations of our device compared to conventional Yagi‐Uda antennas [5,6,7,8,9,10,11] are the use of dual‐feed elements and in‐ and out‐of‐plane constructive interference of the electric dipole, electric quadrupole, and magnetic dipole moments of the 2P‐NAs elements These innovations provide strong CE, high directivity (D), large polarisation extinction ratio (PER) and ultra‐broadband operation—making our device attractive for both telecommunications and other integrated ultra‐broadband applications (e.g. Raman spectroscopy)

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