Silicon-chip-based mid-infrared dual-comb spectroscopy.

The development of a spectroscopy device on a chip that could realize real-time fingerprinting with label-free and high-throughput detection of trace molecules represents one of the big challenges in sensing. Dual-comb spectroscopy (DCS) in the mid-infrared is a powerful technique offering high acquisition rates and signal-to-noise ratios through use of only a single detector with no moving parts. Here, we present a nanophotonic silicon-oninsulator platform designed for mid-infrared (mid-IR) DCS. A single continuous-wave lowpower pump source generates two mutually coherent mode-locked frequency combs spanning from 2.6 to 4.1 μm in two silicon microresonators. A proof-of-principle experiment of vibrational absorption DCS in the liquid phase is achieved acquiring spectra of acetone spanning from 2900 to 3100 nm at 127-GHz (4.2-cm^-1) resolution. These results represent a significant step towards a broadband, mid-IR spectroscopy instrument on a chip for liquid/ condensed matter phase studies. [ABSTRACT FROM AUTHOR]