Cascaded Fiber-based Mid-Infrared Supercontinuum Source

Abstract

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 fiber-based system is shown to generate a flat broadband mid-IR SC covering the entire range from 2 to 10 µm with several 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.

All-fiber 2–6 μm coherent supercontinuum source based on chalcogenide fibers pumped by an amplified mid-IR soliton laser

“…During the last decade, cascaded fiber systems have emerged as attractive and promising solutions for practical, table-top, and robust mid-infrared (mid-IR) supercontinuum (SC) sources with high spectral power density [1]. Most advanced and recently developed all-fiber-based mid-IR SC sources are based on the cascade of silica and soft-glass fibers (usually few-meter long segments), enabling a stepwise extension toward the mid-IR starting from an initial near-IR long-pulse laser [2][3][4]. This implies an optimization procedure for the Raman-induced self-frequency shift of soliton pulses (formed after the initial breakup of the pump pulse) by selecting suitable dispersion-tailored highly nonlinear fiber segments to push forward the SC generation far in the mid-IR.…”