Ultra-high on-chip optical gain fabricated with atomic-layer deposition technology

Efficient and reliable on-chip optical amplifiers and light sources can enable versatile integration of various active functionalities on the silicon platform. Here, we discuss our recent results of ultra-high on-chip optical gain in erbium-based hybrid waveguides with a monolithic, CMOS-compatible and scalable atomic-layer deposition process. The unique layer-by-layer nature of atomic-layer deposition enables atomic scale engineering of the gain layer properties and straightforward integration with silicon integrated waveguides. We have demonstrated up to >20 dB/cm net modal gain per unit length, the highest performance achieved from erbium-based planar waveguides integrated on silicon. Our results show significant advances towards efficient on-chip amplification, opening a route to large-scale integration of various active functionalities on silicon.