Monolithic integration of laser onto multilayer silicon nitride photonic integrated circuits with high efficiency at telecom wavelength

We propose a multilayer silicon nitride (SiN) -on-silicon photonic integrated circuit (PIC) platform with a monolithic laser at the C-band. A tapered edge coupler and a meta-structure-based interlayer directional coupler in the platform were designed to realize low-loss broadband laser-to-chip 3D coupling with small footprint. The coupling length of the interlayer directional coupler and the gap between different SiN layers were optimized as 12.7 mu m and 1.4 mu m. We measured the 1-dB-drop optical operation bandwidth of greater than 76 nm and the coupling loss of 6.1 +/- 0.1 dB at 1550 nm for the interlayer directional coupler. The hybrid integration was demonstrated as a proof of concept for monolithic integration of light sources. The butt-coupling loss of 3.7 +/- 0.1 dB between an on-chip DFB laser and a SiN edge coupler at 1549.48 nm was achieved. This approach opens the possibility of employing monolithic laser in the silicon photonics platform. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

The study introduces a multilayer silicon nitride-on-silicon photonic integrated circuit platform with a monolithic laser at the C-band. The platform features a tapered edge coupler and a meta-structure-based interlayer directional coupler for low-loss broadband laser-to-chip 3D coupling. Optimization of the coupling length and gap between different SiN layers resulted in a large optical operation bandwidth and low coupling loss.