2017/04/30 by Clemens Herkommer, Adrien Billat, Hairun Guo +7 · 328 citations
Engineering · Physics and Astronomy · #Advanced Fiber Laser Technologies #Femtosecond #Frequency comb #Infrared #Laser #Laser-Matter Interactions and Applications #Materials science #Nanophotonics #Optics #Optoelectronics #Photonic Crystal and Fiber Optics #Photonic-crystal fiber #Photonics #Physics #Silicon #Silicon nitride #Silicon photonics #Supercontinuum #Ultrashort pulse #Waveguide #Wavelength #physics.optics
paper · pdf · doi:10.1038/s41566-018-0144-1
published in Nature Photonics 12(6), 330-335 (Nature Portfolio)
arxiv created 2017/06/18 · openalex publication_date 2018/04/13 · arxiv updated 2018/05/10 · openalex created_date 2018/06/13 · openalex updated_date 2026/08/05
Mid-infrared optical frequency combs are of significant interest for molecular spectroscopy due to the large absorption of molecular vibrational modes on one hand, and the ability to implement superior comb-based spectroscopic modalities with increased speed, sensitivity and precision on the other hand. Substantial advances in mid-infrared frequency comb generation have been made in recent years based on nonlinear frequency conversion, microresonator Kerr frequency combs, quantum cascade lasers and mode locking regimes. Here we demonstrate a simple, yet effective method for the direct generation of mid-infrared optical frequency combs in the region from 2.5-4~μ\rm m, i.e. 2500-4000~\rm cm-1 covering a large fraction of the functional group region, directly from a conventional and compact erbium-fiber-based femtosecond laser in the telecommunication band (i.e. 1.55~μ\rm m). The wavelength conversion is based on dispersive wave generation within the supercontinuum process in large-cross-section and dispersion-engineered silicon nitride (\rm Si3N4) waveguides. The long-wavelength dispersive wave, with its position lithographically determined, performs as a mid-infrared frequency comb, whose coherence is demonstrated via optical heterodyne measurements. Such a simple and versatile approach to mid-infrared frequency comb generation is suitable for spectroscopic applications in the first mid-infrared atmospheric window. Moreover, the compactness and simplicity of the approach have the potential to realize compact dual-comb spectrometers. The generated combs have a fine teeth-spacing, making them also suitable for gas phase analysis.