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Highly efficient dual‑level grating couplers for silicon nitride photonics

Highly efficient dual‑level grating couplers for silicon nitride photonics
Highly efficient dual‑level grating couplers for silicon nitride photonics
We propose and numerically demonstrate a versatile strategy that allows designing highly efficient dual-level grating couplers in different silicon nitride-based photonic platforms. The proposed technique, which can generally be applied to an arbitrary silicon nitride film thickness, is based on the simultaneous optimization of two grating coupler levels to obtain high directionality and grating-fibre mode matching at the same time. This is achieved thanks to the use of two different linear apodizations, with opposite signs, applied to the two grating levels, whose design parameters are determined by using a particle swarm optimization method. Numerical simulations were carried out considering different silicon nitride platforms with 150, 300, 400 and 500 nm thicknesses and initially employing silicon as the material for the top level grating coupler. The use of Si-rich silicon nitride with a refractive index in the range 2.7–3.3 for the top layer material enabled to obtain similar performance (coupling efficiency exceeding − 0.45 dB for the 400 nm thick silicon nitride platform) with relaxed fabrication tolerances. To the best of our knowledge, these numerical results represent the best performance ever reported in the literature for silicon nitride grating couplers without the use of any back-reflector.
2045-2322
Vitali, Valerio
4a0d9710-5d64-4703-9554-86d71c4cb0f5
Lacava, Cosimo
d5c4ba41-4f75-4060-afd7-2ab2f51aa35f
Domínguez Bucio, Thalía
83b57799-c566-473c-9b53-92e9c50b4287
Gardes, Frederic
7a49fc6d-dade-4099-b016-c60737cb5bb2
Petropoulos, Periklis
522b02cc-9f3f-468e-bca5-e9f58cc9cad7
Vitali, Valerio
4a0d9710-5d64-4703-9554-86d71c4cb0f5
Lacava, Cosimo
d5c4ba41-4f75-4060-afd7-2ab2f51aa35f
Domínguez Bucio, Thalía
83b57799-c566-473c-9b53-92e9c50b4287
Gardes, Frederic
7a49fc6d-dade-4099-b016-c60737cb5bb2
Petropoulos, Periklis
522b02cc-9f3f-468e-bca5-e9f58cc9cad7

Vitali, Valerio, Lacava, Cosimo, Domínguez Bucio, Thalía, Gardes, Frederic and Petropoulos, Periklis (2022) Highly efficient dual‑level grating couplers for silicon nitride photonics. Scientific Reports, 12 (1), [15436]. (doi:10.1038/s41598-022-19352-9).

Record type: Article

Abstract

We propose and numerically demonstrate a versatile strategy that allows designing highly efficient dual-level grating couplers in different silicon nitride-based photonic platforms. The proposed technique, which can generally be applied to an arbitrary silicon nitride film thickness, is based on the simultaneous optimization of two grating coupler levels to obtain high directionality and grating-fibre mode matching at the same time. This is achieved thanks to the use of two different linear apodizations, with opposite signs, applied to the two grating levels, whose design parameters are determined by using a particle swarm optimization method. Numerical simulations were carried out considering different silicon nitride platforms with 150, 300, 400 and 500 nm thicknesses and initially employing silicon as the material for the top level grating coupler. The use of Si-rich silicon nitride with a refractive index in the range 2.7–3.3 for the top layer material enabled to obtain similar performance (coupling efficiency exceeding − 0.45 dB for the 400 nm thick silicon nitride platform) with relaxed fabrication tolerances. To the best of our knowledge, these numerical results represent the best performance ever reported in the literature for silicon nitride grating couplers without the use of any back-reflector.

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Accepted/In Press date: 29 August 2022
Published date: 14 September 2022
Additional Information: Funding Information: This research was funded by the UK’s EPSRC through Grant EP/T007303/1 “Silicon-rich silicon nitride Nonlinear Integrated Photonic ciRcuits & Systems (juNIPeRS)”. The use of the IRIDIS High Performance Computing Facility at the University of Southampton is acknowledged. The data for this work is accessible through the University of Southampton Institutional Research Repository https://doi.org/10.5258/SOTON/D2229. Funding Information: This research was funded by the UK’s EPSRC through Grant EP/T007303/1 “Silicon-rich silicon nitride Nonlinear Integrated Photonic ciRcuits & Systems (juNIPeRS)”. The use of the IRIDIS High Performance Computing Facility at the University of Southampton is acknowledged. The data for this work is accessible through the University of Southampton Institutional Research Repository https://doi.org/10.5258/SOTON/D2229 . Publisher Copyright: © 2022, The Author(s).

Identifiers

Local EPrints ID: 470559
URI: http://eprints.soton.ac.uk/id/eprint/470559
ISSN: 2045-2322
PURE UUID: b78e6f19-421c-439d-8614-18b3b0718d90
ORCID for Thalía Domínguez Bucio: ORCID iD orcid.org/0000-0002-3664-1403
ORCID for Frederic Gardes: ORCID iD orcid.org/0000-0003-1400-3272
ORCID for Periklis Petropoulos: ORCID iD orcid.org/0000-0002-1576-8034

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Date deposited: 13 Oct 2022 16:30
Last modified: 20 Feb 2024 03:04

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Contributors

Author: Valerio Vitali
Author: Cosimo Lacava
Author: Frederic Gardes ORCID iD

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