Mid-infrared supercontinuum (SC) sources in the 2 to 20 µm molecular fingerprint region are in high demand for a wide range of applications including optical coherence tomography, remote sensing, molecular spectroscopy, and hyperspectral imaging. In this work, we investigate mid-IR SC generation in a cascaded silica-ZBLAN-chalcogenide fiber system directly pumped with a commercially available 460-ps pulsed fiber laser operating in the telecommunications window at 1.55 µm. This all-fiber system is shown to generate a flat broadband mid-IR SC covering the entire range from 2 to 10 µm with severaltens of mWof output power. This technique paves the way for cheaper, practical, and robust broadband SC sources in the mid-IR without the requirement of mid-infrared pump sources or Thulium-dopedfiber amplifiers. We also describe a fully realistic numerical model used to simulate the nonlinear pulse propagation through the cascaded fiber system and we use our numerical results to discuss the physical processes underlying the spectral broadening in the cascaded system. We conclude with recommendations to optimize the current cascaded systems based on our simulation results.
Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm−1
