L-shaped grating couplers engineered with subwavelength metamaterial for sub-decibel coupling loss

D. Benedikovic (1) , C. Alonso-Ramos (1) , S. Guerber (2) , V Vakarin , G. Marcaud (1) , X. Le Roux (1) , P Cheben , E. Cassan (3) , D. Marris-Morini (3) , F. Boeuf (4) , C Baudot , L. Vivien (3)

1 C2N (UMR_9001) - Centre de Nanosciences et Nanotechnologies
2 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
3 IEF - Institut d'électronique fondamentale
4 ST-CROLLES - STMicroelectronics [Crolles]

Practically attractive nanophotonic technologies, mostly realized on mature silicon-on-insulator (SOI) substrates, call upon availability of efficient input/output grating-coupled optical interfaces. In this work, we demonstrate, both theoretically and experimentally, ultra-directional L-shaped grating couplers for low-loss light coupling between standard optical fibres and SOI chips. Experimentally, we show grating couplers without and with subwavelength (SWG) transition, seamlessly fabricated with a 193-nm deep-ultraviolet lithography. Coupling loss of-2.7 dB is measured with a low return loss as low as-20 dB. In addition, we propose an apodized L-shaped grating coupler layouts with coupling loss below 1 dB. Apodized fiber-chip grating couplers are designed with a sub-decibel coupling performance, together with substantially relaxed requirements in terms of minimum feature dimensions.

Mots clés: fibre-chip grating couplers; deep-ultraviolet technology; subwavelength gratings; metamaterials; silicon-on-insulator platform; silicon photonics

Domaines: Optique / photonique; Micro et nanotechnologies/Microélectronique

D. Benedikovic, C. Alonso-Ramos, S. Guerber, V Vakarin, G. Marcaud, et al.. L-shaped grating couplers engineered with subwavelength metamaterial for sub-decibel coupling loss. 2019 European Conference on Integrated Optics, Apr 2019, Ghent, Belgium. ⟨hal-02539548⟩