Optical frequency combs (OFC) are light sources characterized by a spectrum comprising millions of laser lines, evenly distributed in frequency. This uniform frequency spacing establishes a crucial connection between the radiofrequency (RF) and optical frequency bands within the electromagnetic spectrum. This characteristic has profoundly transformed the fields of frequency metrology and precision laser spectroscopy. Recently, their application scope has expanded to encompass numerous new applications. Among these, their distinctive features have been harnessed in precision distance measurement experiments, as well as demonstrations of optical waveform and microwave synthesis.
Moreover, experiments in "dual-comb spectroscopy" have showcased broadband Fourier Transform Infrared (FTIR) spectroscopy with unprecedented resolution, sensitivity, and acquisition speeds. However, many of these demonstrations have relied on bulky experimental setups, hindering widespread deployment.
Our aim is to develop frequency combs on optical chips that can be mass-produced using CMOS technology. Unlike current chip-scale Kerr comb-based solutions, they do not require powerful continuous-wave laser optical pumping and can feature narrower comb spacing. In our project, conducted in collaboration with numerous partners, we have shown the feasibility of this approach. Specifically, we have demonstrated the ability to conduct dual-comb measurements of gases. This indicates low losses with sufficient resolution to resolve gas absorption lines.
