Mid-infrared dual-comb QCLs integrated with beam combiner based on Ge-on-Si platform

Mid-infrared dual-comb spectroscopy, a powerful fast and broadband technique involves two combs that are mixed by free-space beam combining and generating beat signal. Here, we demonstrate for the first time on-chip QCLs integrated with combiners by leveraging Ge-on-Si platform and 3D self-alignment flip-chip assembly.