Chip-Scale Comb Lasers for Co-Packaged Optics

The exponential growth of artificial intelligence and machine learning workloads is putting unprecedented demand on datacentre interconnects. Co-packaged optics (CPO) and optical I/O (OIO) are emerging as solutions to overcome the bandwidth, power, and faceplate density limits of pluggable transceivers. However, current implementations rely on laser arrays that face scaling challenges in wavelength count, stability, accuracy. This paper introduces a chip-scale frequency comb approach to external laser sources (ELS), being developed within the European Innovation Council (EIC) COCOPOP project. Based on silicon nitride (SiN) microresonator combs and injection-locked demultiplexing using laser arrays, the technology overcomes the primary challenge with optical combs, namely the low power per wavelength. These advances provide a path toward comb-based datacentre interconnects, which can enable continued scaling of bandwidth and capacity while also reducing the laser power dissipation through the use of coherent detection.