Ambient-Stable NIR Nanolasing: Monolithic Integration of PbS CQDs on a Silicon Photonic Platform

Nanolasers based on colloidal quantum dots (CQDs), while transformative in the visible spectrum, face critical roadblocks in the near-infrared (NIR) regime due to material instability under ambient conditions and ultrafast Auger recombination in large NIR CQDs. Here, these limitations are addressed through zinc-doped PbS CQDs that suppress nonradiative decay, integrated with compact high-Q silicon nanobeam cavities to leverage the Purcell effect for efficiently guiding spontaneous emission into laser modes, thereby significantly reducing the threshold power. This work demonstrates a monolithic CQD-integrated silicon photonic platform that achieves NIR lasing under pulsed optical pumping, featuring a record narrow linewidth of 0.29 nm (0.15 meV) at 1579.20 nm and an ultralow threshold of 127 µJ cm^-2. Notably, under continuous-wave (CW) pumping, the device exhibits cavity-filtered spontaneous emission with a sub-nanometer linewidth across the 1350-1600 nm spectrum. This emission showcases <6% peak power decay over 15 h at 300 K, robust performance up to 360 K, and negligible degradation after 250 days of ambient storage. By monolithically integrating solution-processed CQDs with CMOS-compatible silicon photonics, this platform establishes a reliable, scalable, and low-cost route toward multiwavelength on-chip nanolaser arrays in the NIR regime, unlocking transformative potential for compact photonic technologies in imaging, sensing, and communications.