Monolithic Integration of InAs Quantum Dot Lasers with Waveguide Photodetector on CMOS-Compatible (001) Silicon

Silicon photonics requires CMOS-compatible, on-chip, efficient laser diodes (LDs) and low-noise photodetectors (PDs). Here, we demonstrate the monolithic integration of InAs QD LDs and waveguide PDs (WPDs) on CMOS-compatible (001) silicon by employing an identical epitaxial structure. The device exhibits bias-selective operation with both components isolated by XeF₂-assisted focused ion beam trenching, a strategy ideal for LDs and PDs that require precise positioning yet occupy a minimal package footprint. The LD exhibits a low threshold current density of 170 A/cm² and a single-facet continuous-wave output power of 48 mW, while the WPD shows a low dark current density of 4.9 × 10^-5 A/cm² at -1 V and a broad O-band spectral response. The integrated LD-WPD system shows a clear correlation between LD output power and WPD photocurrent with an estimated responsivity of 0.118 A/W. Our results demonstrate the feasibility of on-chip power monitoring, paving the way for compact, reliable, and high-density photonic integration.