Abstract
In this paper, 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 fiber-based system is shown
to generate a flat broadband mid-IR SC covering the entire range from 2
to 10 µm with tens of mW of output power. This technique paves the way
for low cost, practical, and robust broadband SC sources in the mid-IR
without the requirement of mid-infrared pump sources or Thulium-doped
fiber amplifiers. We also describe a fully realistic numerical model
used to simulate the nonlinear pulse propagation through the cascaded
fiber system and 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 the simulation results.