Efficient single-etch surface grating couplers in silicon nitride platforms for telecom and datacom wavebands

¹ Dept. Multimedia and Information-Communication Technologies, University of Žilina, 01026 Žilina, Slovakia
² Dept. Electronics, Carleton University, ON K1S 5B6 Ottawa, Canada
³ Centre de Nanosciences et de Nanotechnologies, CNRS, Universite Paris-Saclay, 91120 Palaiseau, France
⁴ National Research Council Canada, ON K1A 0R6 Ottawa, Canada
⁵ University Science Park, University of Žilina, 01026 Žilina, Slovakia

^* Corresponding author: daniel.benedikovic@uniza.sk

Published online: 18 October 2023

Abstract

We present designs and experiments of single-etched amorphous silicon (α-Si) surface grating couplers on a silicon nitride (SiN) waveguide, operating at the telecom (C-band) and datacom (O-band) wavebands. SiN-only grating couplers demonstrate experimental coupling loss of -3.9 dB at 1.55 μm wavelength with a 1-dB bandwidth of 37 nm. Utilizing the hybrid α-Si/SiN platform with subwavelength grating structure, we obtain improved coupling performances, with the optimized fiber-chip coupling loss of -2.0 dB and a 1-dB spectral bandwidth of 42 nm centered at 1.31 μm.