Monolithic integration of quantum dot lasers and amplifiers in silicon photonic circuits with high coupling efficiency

Silicon photonics constitutes the cornerstone technology of on-chip optical interconnects. However, silicon cannot generate or amplify light, and the seamless integration of gain elements with passive waveguides on silicon substrates remains a critical challenge. In this work, we propose a strategy to effectively address the waveguide coupling bottleneck between III/V gain regions and silicon photonic circuits to establish a scalable, monolithic, and CMOS-compatible linked platform. Our approach exploits silicon nitride waveguides deposited at low temperature and coupled through anti-reflective layers to epitaxially grown InAs/GaAs quantum dot gain regions on a silicon wafer. The fabricated junctions exhibited coupling losses below 1.5 dB and back-reflections close to −15dB for a normal interface. Continuous-wave lasers with distributed Bragg reflectors were experimentally demonstrated with threshold currents below 215 mA at room temperature and a maximum single-port output power exceeding 2 mW. To the best of our knowledge, the first waveguide-coupled monolithically integrated electrically pumped optical amplifiers on silicon substrate are also demonstrated, with net gains greater than 5 dB and a 3 dB optical bandwidth of 46 nm. This advance enables the cost-effective co-integration of positive net gain amplifiers and broadband passive components on silicon, paving the way for next-generation data center interconnects.