Low-loss, compact, spot-size-converter based vertical couplers for photonic integrated circuits

Authors

Praveen K.J. Singaravelu, Centre for Advanced Photonics & Process Analysis, Cork Institute of Technology, Cork, Ireland; Tyndall National Institute, Cork, IrelandFollow
G.C.R. Devarapu, Centre for Advanced Photonics & Process Analysis, Cork Institute of Technology, Cork, Ireland,Tyndall National Institute, Cork, Ireland; Scottish Universities Physics Alliance, School of Physics & Astronomy, St Andrews, UKFollow
Sebastian A. Schulz, Centre for Advanced Photonics & Process Analysis, Cork Institute of Technology, Cork, Ireland; Scottish Universities Physics Alliance, School of Physics & Astronomy, St Andrews, UK
Quentin Wilmart, University Grenoble Alpes, CEA, LETI, MINATEC Campus, CEA-Grenoble, Grenoble, F38054, France
Stéphane Malhouitre, University Grenoble Alpes, CEA, LETI, MINATEC Campus, CEA-Grenoble, Grenoble, F38054, France.
Ségolène Olivier, University Grenoble Alpes, CEA, LETI, MINATEC Campus, CEA-Grenoble, Grenoble, F38054, France
Liam O’Faolain, CAPPA Centre for Advanced Photonics & Process Analysis, Cork Institute of Technology, Cork, Ireland; Tyndall National Institute, Cork, Ireland; Scottish Universities Physics Alliance, School of Physics & Astronomy, St Andrews, UK

ORCID

https://orcid.org/0000-0001-7572-6090

Document Type

Article

Disciplines

Electrical and Computer Engineering | Electromagnetics and Photonics | Engineering

Publication Details

Journal of Physics D: Applied Physics, Volume 52, Number 21

Abstract

In recent years, the monolithic integration of new materials such as SiN, Ge and LiNbO3 on silicon (Si) has become important to the Si photonics community due to the possibility of combining the advantages of both material systems. However, efficient coupling between the two different layers is challenging. In this work, we present a spot size converter based on a two-tier taper structure to couple the optical mode adiabatically between Si and SiN. The fabricated devices show a coupling loss as low as 0.058 dB  ±  0.01 dB per transition at 1525 nm. The low coupling loss between the Si to SiN, and vice versa, reveals that this interlayer transition occurs adiabatically for short taper lengths (<200 µm). The high refractive index contrast between the Si and SiN is overcome by matching the optical impedance. The proposed two-tier taper structure provides a new platform for optoelectronic integration and a route towards 3D photonic integrated circuits.

Recommended Citation

Singaravelu, P.K.J., Devarapu, G.C.R., Schulz, S.A., Wilmart, Q., Malhouitre, S., Olivier, S. and O‘Faolain, L. (2019). Low-loss, compact, spot-size-converter based vertical couplers for photonic integrated circuits. Journal of Physics D: Applied Physics, 52(21), p.214001. ‌