On-Chip Single-Mode Distributed Feedback Colloidal Quantum Dot Laser under Nanosecond Pumping

We report on a hybrid integrated distributed feedback (DFB) laser fabricated using the colloidal quantum dots (QDs)/silicon nitride (SiN) integration platform. The DFB laser is fabricated with a CMOS-compatible process and consists of a waveguide stack in which a QD layer is embedded between two SiN layers to enhance the coupling of the QD to the optical waveguide mode. Following characterization of the intrinsic properties of the CdSe/CdS core/shell QDs using transient absorption spectroscopy, we demonstrate single-mode lasing upon nanosecond optical pumping. With a 7 ns pump pulse, the lasing threshold is 270 μJ/cm². This result attests to the potential of colloidal QDs as an enabling gain material for integrated SiN photonics, and it showcases the design versatility of hybrid integrated photonics platforms based on colloidal QDs.