Hybrid Si/III-V quantum cascade lasers integrated on a phase-matched mid-infrared silicon photonic platform.

The increasing demand for mid-infrared (MIR) photonic integrated devices in spectroscopic applications has driven the development of essential building blocks for chemical sensing, including quantum cascade lasers (QCLs), MIR silicon photonic platforms and integrated detectors. A fully integrated MIR silicon photonic chip would enable cost-effective mass production using CMOS-compatible fabrication, paving the way for consumer-grade MIR devices and large-scale onsite sensing applications. However, the integration of QCLs with MIR silicon platforms remains a major challenge due to inefficient optical coupling between the III-V active region and silicon waveguides, leading to high insertion losses and reduced device performance. In this work, we demonstrate the heterogeneous integration of a QCL onto a believed to be novel high-index-contrast, phase-matched silicon on nitride on insulator (SONOI) photonic platform using molecular bonding. By leveraging a phase-matching condition, we implement an adiabatic coupling scheme that ensures efficient optical power transfer from the III-V active region to the silicon waveguides, overcoming a key limitation of previous approaches. The resulting hybrid distributed-feedback (DFB) QCL exhibits single-mode emission at 4.315 µm and operates in pulsed mode up to 72 °C. This advancement opens new possibilities for fully integrated MIR photonic circuits, with potential applications in environmental monitoring, biomedical diagnostics, and industrial sensing.