Abstract

The midinfrared spectral region provides direct access to molecular vibrational transitions. The stronger coupling in the midinfrared creates possibilities for sensitive molecular detection [1] and control. As technology advances, midinfrared laser sources are becoming more practical, particularly as femtosecond fiber lasers can now drive nonlinear conversion with small and robust systems [2]. Shorter wavelength midinfrared sources around 3-5 µm wavelength are becoming accessible with efficient nonlinear crystals such as periodically-poled lithium niobate easily available. Sources at longer wavelengths are less common, and at fairly low power, given the poor quantum efficiency of going to such long wavelengths. We have previously shown a laser system with a good balance of output power to system size, a femtosecond midinfrared frequency comb with up to 69 mW of power with broad bandwidths and tunable from 6-11 µm [2]. We have built two of these systems, and combined them to create a unique high-powered, midinfrared dual comb spectroscopy system that will open possibilities for measurements including lossy techniques such as multipass, or over long distances with significant scattering and absorption.

© 2019 IEEE