High Performance Monolithic Integration of Light Amplifiers in Silicon Photonic Circuits

Abstract Silicon photonics constitutes the cornerstone technology of on-chip optical interconnects. However, the seamless integration of gain elements with passive waveguides on silicon substrates remains a critical challenge. In this work, we demonstrate monolithically integrated III/V gain regions on a silicon wafer interfaced with silicon nitride waveguides exhibiting coupling losses below 1.5 dB and back-reflections close to -13 dB 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 fibre coupled power exceeding 2 mW. The first 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. The proposed strategy effectively addresses the waveguide coupling bottleneck between III/V gain regions and silicon photonic circuits, establishing a scalable, monolithic and CMOS-compatible linked platform. 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 centre interconnects.