Ultra-compact InGaAs/GaAs nano-ridge laser monolithically grown on 300 mm silicon substrate.

Compact and low-threshold III-V semiconductor lasers are considered to be promising light sources for the silicon photonics platform, as they could offer a small footprint and low energy consumption. However, the significant lattice mismatch between III-V materials and silicon poses a fundamental challenge for the monolithic integration of such lasers on a silicon substrate. Using aspect ratio trapping and nano-ridge engineering, it has been shown this challenge can be overcome. However, thus far, only devices with cavity lengths of several hundred micrometers have shown a laser operation. Here, we show what we believe to be a novel approach whereby an amorphous silicon grating is deposited on the sidewalls of the nano-ridge, allowing for much stronger feedback and much shorter cavity lengths. Based on this approach, we achieved lasing with a threshold density of 9.9 kW/cm² under pulsed optical pumping, for a device with a cavity length as small as ∼16 µm. The side-mode suppression ratio and linewidth of the laser reach 24 dB and 1.25 nm under 25 kW/cm². This laser not only demonstrates the high quality of the epitaxial material but also establishes a novel route to realize an ultra-compact electrically driven light source for future high-density and massively scalable silicon photonic integrated circuits.